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Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1
- Conference date: 22-23 Mar 2016
- Location: Qatar National Convention Center (QNCC), Doha, Qatar
- Volume number: 2016
- Published: 21 March 2016
101 - 200 of 656 results
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Machine Learning-Based Building Energy Consumption Prediction
Authors: Nora El-Gohary and Kadir AmasyaliEnergy is the lifeblood of modern societies. In the past decades, the world's energy consumption and associated CO2 emissions have increased rapidly due to the increases in population and comfort demand of people. In this decade, the increase in energy consumption and associated CO2 emissions are expected to continue due to the demand coming from developing countries such as China, India, and some Middle East countries. Negative environmental impacts, such as air pollution and global warming, are being triggered by the generation and use of non-renewable energy, including oil and natural gas. Buildings are a significant source of the world's energy consumption. The building sector is responsible for 39% and 40% of the energy consumption and 38% and 36% of the CO2 emissions in the U.S. (Becerik-Gerber et al. 2014) and Europe (Ahmad et al. 2014), respectively. Buildings, therefore, offer a great potential for reducing the world's energy consumption and limiting the negative impacts caused by the use of non-renewable sources. Improving building energy efficiency is one of the best strategies for reducing the energy consumption of buildings, while maintaining the comfort and well-being of the building occupants. Building occupants care about their comfort and well-being, as well as about the energy cost and the environment. A recent study showed that thermal comfort, visual comfort, indoor air quality, health, personal productivity, energy cost saving, and environmental protection are moderately important or higher to residential and office building occupants (Amasyali and El-Gohary 2016).
In this regard, building energy efficiency drew a lot of research attention; a relatively large number of research studies have been undertaken in the field of building energy efficiency. These efforts can be classified into five categories: (1) efforts to improve the efficiency of building appliances and materials; (2) efforts toward increasing the use of renewable energy sources; (3) new policies, incentives, and regulations to reduce energy consumption; (4) efforts toward improving occupant behavior, and (5) efforts to automate building control. Studies in all these categories require accurate building energy consumption prediction for improved energy decision making. Building energy software tools (physical models), such as EnergyPlus and eQuest, are being widely used for energy consumption prediction. These tools are, however, very elaborate and therefore requires a significant number of input parameters that are not always available to users. In order to predict energy consumption of buildings without many input parameters, data-driven models were developed. Data-driven approaches utilize historical input data (e.g., outdoor weather conditions, electricity consumption) for developing a prediction model. In any data-driven approach, developing a model consists of four steps: data collection, data preprocessing, model training, and model testing. In the area of building energy consumption prediction, the types of data collected could be data from sensors that are utilized in empirical building energy studies, data generated by a building energy simulation software, or data from publicly available generic datasets (e.g., datasets provided for energy consumption prediction competitions). Data preprocessing includes data cleaning, data transformation, data normalization, and data interpolation. Model training is the training of the prediction model using the historical data. Support Vector Machine (SVM), Artificial Neural Networks (ANN), decision tree, and statistical techniques are the most commonly used training algorithms and techniques. Model testing is the evaluation of the prediction model using some standard evaluation measures.
This paper presents a data-driven building energy consumption model. The authors used publicly available generic data and sensor data: the ASHRAE's Great Building Energy Predictor Shootout dataset (ASHRAE dataset) and a dataset gathered from an office building in Philadelphia, PA which was instrumented and monitored for this study (PA dataset). The lengths of the ASHRAE and PA datasets are six and two months, respectively. These datasets were cleaned, transformed to the format required by the learning algorithm, and normalized. SVM was used as the training algorithm. SVM is a kernel-based machine learning (ML) algorithm that can be used for both regression and classification (Wu et al. 2008). The goal of this algorithm is to find a function f(x) that has at most epsilon (ε) deviation from the actually obtained target yi for all the training data and at the same time is as flat as possible (Vapnik, 1995). The algorithm can solve non-linear problems even with a small amount of training data (Zhao and Magoules 2012). SVM is one of the most robust and accurate algorithms and has been listed in the top ten most influential data mining algorithms in the research community by the IEEE International Conference on Data Mining (Wu et al. 2008). It was found to outperform other ML algorithms in numerous applications. For model testing, the coefficient of variation (CV) and the mean bias error (MBE) were used to evaluate the performance of the models in predicting energy consumption. CV and MBE are performance criteria, provided by ASHRAE, for evaluating energy consumption level prediction algorithms. CV determines how much the overall prediction error varies with respect to the target's mean and MBE determines how likely a particular model is to over-estimate or under-estimate the actual data (Edwards et al. 2012).
The LIBSVM software package was used to implement the SVM algorithm. Eight input parameters were used for the prediction model: outdoor dry-bulb temperature of the current hour, outdoor dry bulb temperature of the previous hour, solar radiation intensity of the current hour, solar radiation intensity of the previous hour, wind speed of the current hour, relative humidity of current hour, energy consumption of the previous hour, and energy consumption of the two hours ago. The following model parameters were used: nu-SVR (type of SVM), radial basis function (kernel type), and 1500000 (cost). As shown in Fig. 1, the predicted results of the model on the ASHRAE dataset, showed a good fitness with the actual energy consumption. In the end, the models showed that it has many promising features that could make it more reliable for effective energy decision making. The model achieved 3.71% CV and 0.30% MBE.
The authors are currently working on improving the accuracy of the model based on the ASHRAE dataset, as well as extending the model to an occupant-behavior-sensitive energy consumption prediction model based on the PA dataset. The model will be able to predict overall building energy consumption on a daily, hourly, and sub-hourly basis. It will predict energy consumption based on (1) indoor environmental condition data (e.g., indoor temperature and relative humidity), (2) occupant energy use behavior data (e.g., thermostat setpoints), and (3) outdoor weather condition data (e.g., ambient temperature and ambient relative humidity). The authors will also focus on: (1) assessing the effectiveness of utilizing indoor environmental condition data and occupant energy use behavior data for energy consumption prediction, using sensitivity analysis that are going to be conducted individually for the daily, hourly, and sub-hourly prediction models, and
(2) comparing the performances of the daily, hourly and sub-hourly prediction models. References: Ahmad, A. S., Hassan, M. Y., Abdullah, M. P., Rahman, H. A., Hussin, F., Abdullah, H., & Saidur, R. (2014). A review on applications of ANN and SVM for building electrical energy consumption forecasting. Renewable and Sustainable Energy Reviews, 33, 102–109.
Amasyali, K., & El-Gohary, N. M. (2016). Energy-related values and satisfaction levels of residential and office building occupants. Building and Environment, 95, 251–263.
Becerik-Gerber, B., Siddiqui, M. K., Brilakis, I., El-Anwar, O., El-Gohary, N., Mahfouz, T., … & Kandil, A. A. (2013). Civil engineering grand challenges: Opportunities for data sensing, information analysis, and knowledge discovery. Journal of Computing in Civil Engineering, 28(4), 04014013.
Edwards, R. E., New, J., & Parker, L. E. (2012). Predicting future hourly residential electrical consumption: A machine learning case study. Energy and Buildings, 49, 591–603.
Vapnik, V (1995). The Nature of Statistical Learning Theory. Springer-Verlag New York, Inc., New York, NY, USA.
Wu, X., Kumar, V., Quinlan, J. R., Ghosh, J., Yang, Q., Motoda, H., … & Steinberg, D. (2008). Top 10 algorithms in data mining. Knowledge and Information Systems, 14(1), 1–37.
Zhao, H. X., & Magoulès, F. (2012). A review on the prediction of building energy consumption. Renewable and Sustainable Energy Reviews, 16(6), 3586–3592.
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Effect of Surface Oxidation on Performance of Ti3C2Tx/MO Composite as Anode Materials for Lithium Ion Batteries
By Adnan AliRecently, a new group of 2D material showed a great promise in supercapacitors and batteries application due to their good conductivity as well as hydrophilic nature [1]. It has general formula Mn+1Xn, where n = 1, 2 or 3, M is an early transitional metal and X is C and/or N [2]. According to X-ray photoelectron spectroscopy (XPS) and energy dispersive x-ray spectrometry (EDS) studies, MXenes can be terminated with a mixture of O, OH, and/or F groups depending on the chemical etching method and post-treatment. The as-synthesized MXenes are electronically conducting and hydrophilic, which is a unique combination. Ultrasonication can be used to delaminate the 2D layers and produce single-layer and few-layered flake [3].
As MXenes are hydrophilic, once delaminated, they form stable, surfactant-free colloidal solutions in water. The possibility of intercalating MXenes with various organic molecules plays a critical role for utilizing MXene in a range of applications, from polymer reinforcements to energy storage systems. The MXenes’ 2D morphology, together with to their good electronic conductivities, render them strong candidates for many applications that range from sensors and electronic device materials to catalysts in the chemical industry, conductive reinforcement additives to polymers, and electrochemical energy storage materials, among many others [4].
We have used hydrothermal route to synthesize nanocomposite material i.e. Ti3C2Tx/MO (MO = Fe2O3, Co3O4). After hydrothermal treatment, nanocomposite was calcinated at 400°C for 4 hours to get rid of entrapped moisture. Nano-composite was characterized using scanning electron microscopy, transmission electron microscopy and X-ray diffraction. After synthesis, nanocomposite was applied as anode in lithium ion battery. Anode was fabricated as thin film using doctor blade on copper foil.
Ti3C2Tx/Fe2O3 composite as anode material exhibited discharge and charge capacities of 190 and 120 mAh/g, respectively. Characterization shows that the MO nanoparticles are not uniformly distributed and also X-ray diffraction analysis has confirmed that Ti3C2Tx has oxidized during hydrothermal treatment. Due to oxidation, the surface of Ti3C2Tx was decomposed to TiO2 and leaving carbon sheets behind which played a big role in decreasing conductivity of the anode. In turn, it has greatly affected its performance as anode material in the lithium ion batteries. To enhance its performance as anode material in Lithium ion batteries, it is extremely important to protect it from oxidizing. For this purpose, it should be exfoliated in a medium other than water. Besides this, metal oxide should be uniformly distributed.
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Qatar: A Valuable Resource for Autochthonous Microalgae with High Potential for Biofuel Production and Food Security
Authors: Imen Saadaoui, Touria Bounnit, Ghamza Al Ghazal and Hareb Al JabriAlgae-derived products, in particular biodiesel, have received increased interest over recent years due to their advantages over fossil fuel derived products. The ability of algae to grow in different qualities of water, with high areal biomass productivities, and photoautotrophic capacity using sunlight and CO2 as a source of energy, are just of few of their advantages. Due to the high biodiversity of microalgae and cyanobacteria, the selection of a suitable strain is paramount for successful development and commercial application of microalgae, be it for biodiesel production or, other applications such as products for the nutritional, pharmaceutical and chemical industries. This encouraged the scientific community to establish supporting culture collections of marine and fresh water microalgae and cyanobacteria from a range of diverse environments.
The isolation of autochthonous microalgae, with high lipid-contents and biomass productivities is a crucial aspect of the development of commercial production of microalgae-based biodiesel as well as food security in land-locked locales. This is especially important for deployments in climates such as are found in Qatar, a peninsula in the west Arabian Gulf, which is characterized by an extreme desert climate.
The present research work describes the establishment of the Qatar University Culture Collection of Cyanobacteria and Microalgae (QUCCCM). Indeed, different strains of cyanobacteria and microalgae were isolated from various local environments, ranging from freshwater bodies to marine environments, as well as from soil, sabkha and rocks. Strains were subjected to intensive purification and subculturing, and characterized at the morphological and molecular levels. Selected strains were characterized for growth rate, and secondary metabolite production in order to identify important strains with high potential for large-scale outdoor culture, specifically for biofuel production.
53 autochthonous strains of microalgae were isolated from various freshwater, marine and terrestrial environments in Qatar that led to the establishment of the Qatar University Culture Collection of Cyanobacteria and Microalgae (QUCCCM). Strains were identified via ribotyping and characterized in terms of growth rate and lipid production. 13 different known genera were identified, with the distribution analysis showing Chlorella as the most abundant fresh-water known genus (22.64%), followed by Chlorocystis (13.21%). Several microalgae strains belonging to the same classification showed significant genotypic diversity. Furthermore, several novel strains were identified (20.75%). Furthermore, several novel strains were identified. Growth rate analysis evidenced a thermo and halotolerant Nannochloris isolate QUCCCM31 able to tolerate 45°C and wide salinity range 35–100 ppt. Determination of lipid content and lipid profiling indicated the presence of promising strains for biodiesel production such as Nannochloris sp. (strain QUCCCM31) with a promising FAME profile for biodiesel production. This strain also produced nervonic acid, a C24:1 straight chain fatty acid of high pharmaceutical potential.
Our results show heterogeneity in the Qatar Culture Collection and highlight the presence of Nannochloris sp., strain QUCCCM31, very promising for biodiesel production. The presence of the nervonic acid in the FAME profile increase amply the importance of this strain and enlarge its application for pharmaceutical purposes.
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New Fault-Tolerant Control Approach for a Reconfigurable Grid-Connected PV System
Authors: Mohamed Trabelsi and Haitham Abu-RubBackground & Objectives: Power converters have become over the last decades an enabling technology for PV applications. As demonstrated by scientific literature on the subject, current research efforts are directed toward the use of intermediate solutions between fully centralized and totally distributed (one inverter for each panel or strings of panels) PV grid connection architectures, for cost, reliability and maintenance concerns. Within this trend, topologies of utility scale PV inverters are moving towards Multi-Level Inverters (MLI), which provide better power quality, lighter passive filtering components, and potential to eliminate bulky line frequency transformers. However, in high performance grid-connected PV systems, the failure of the power electronics converters has very serious consequences on the overall system operation. In view of an optimal utilization of the generated electrical power and as per the general fault-tolerance requirements, deploying a power electronics converter capable of continuing to operate effectively in the presence of any single point failure is essential for such as systems. A large-scale solar plant needs to tolerate short-term malfunctions while maintaining the inverter connected to the grid and eventually provide grid support.
One of the main advantages of Cascaded H-Bridge (CHB) MLI is the modularity. A CHB inverter employs many partially separate power modules (cells). If these cells equipped with a bypass switching device (external switch), then if one of the power modules fails it can be bypassed and operation can continue at reduced capacity. This even allows the faulty cell to be replaced by a new one without turning off the system. However, bypassing a module reduces the voltage and power available from the inverter. Then, the problem becomes how to obtain the highest power level with the remaining operative cells.
Moreover, the association of a quasi Z-Source (qZS) network with a CHB MLI was deeply investigated in the last decade for grid-tied PV systems. This single-stage mix-topology is characterized by high-quality staircase output voltage with lower harmonic distortions, independent DC-link voltage compensation with the special voltage step-up/down function in a single-stage power conversion, and independent control of the power delivery with high reliability.
By taking advantage of the high CHB inverter's modularity and flexibility of the qZS network in controlling the DC-link voltage, this research work proposes a new fault-tolerant control strategy for a reconfigurable grid-connected PV system. Methods: The system under study consists of a three-phase sixteen-cell CHB inverter where each module is fed by a qZS network (Fig. 1). The proposed combined controller achieves grid-tie current injection, DC-link voltage balance for all qZS-CHB inverter modules, anti-islanding protection, and fault-tolerant operation. The fault-tolerance feature is explored and discussed for two modulation techniques, which are the Level-Shifted Pulse Width Modulation (LSPWM) and Pulse Width Amplitude Modulation (PWAM). The proposed strategy can be easily implemented without extra hardware requirements. It takes into account key crucial factors for high-efficiency and reliability grid-connected PV systems such as; cost reduction (selection of high efficient and high performing qZS-CHB MLI topology), high power quality (grid current injection with unity power factor and low harmonics distortion), active anti-islanding protection (according to grid codes), and fault-tolerance (continuous operation during malfunction of some system components, which leads to the system reconfiguration). The fault-tolerant design is taking advantage of the large number of redundant switching states for the same output voltage level, which characterizes the selected cascaded topology. However, one can note that this redundancy is effective only for the intermediate levels output voltages, while the extreme levels (highest and lowest levels) are achieved by only one switching state. Accordingly, the proposed approach offers circuit reconfiguration (based on a measurement based fault detection strategy) and voltage stress adjustment to achieve a balanced line-to-line voltage when a fault occurs.
Moreover, Battery Energy Storage Sources (BESS) are used as additional source of energy to support the grid at fault times. At normal operating conditions, the BESS are used to store the excess power available from the PV to avoid the over voltage state. At fault conditions, the BESS could be used to provide the amount of power lost because of the failure of one or more of the inverter modules.
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Removal of Lead Ions from Aqueous Solutions Using Polyaniline Polystyrene Nanocomposites
Authors: Jolly Bhadra, Noora Jabor Al-Thani and Abdullah Alashraf Abul BakerBackground and objectives
Water pollution is an issue of grave importance worldwide, especially in countries that boast of a large number of industries. High concentration of heavy metal ions such as lead, nickel, etc are often found in industrial waste water and can have adverse affects on human health. Over the years a variety of methods, both physical and chemical ones, are reported to have been used for removal of heavy metal ions from water such as filtration and advanced oxidation [1, 2], etc. Adsorption is among the most widely used techniques due to its simplicity, reasonable operational conditions and cost-effective nature. The primary physical property of any absorbent is its surface area and structure. PANI is used due to the presence of primary and secondary amines functional groups which absorb heavy metals. However, due to poor solubility of PANI in common solvents it is made into composite with polystyrene which has strong mechanical properties. In this study a PS/PANI nanocomposite was prepared using the casting method; the composite was then investigated for its heavy metal ion absorption potential.
Methodology
PANI is obtained using dispersion polymerization by the usual technique defined in the literature [14, 15]. In order to prepare PANI/PS a mixture of toluene and sulfuric acid is used to get the composite. 0.05 g polystyrene, 0.95 g PANI mixed in 13:13 ml sulfuric acid and toluene solution and stirred at room temperature for 4 hours. The composite is kept on petri disc overnight and dried samples were heated at 50°C for 3 hours. Sulfuric acid was removed by washing the precipitate with distilled water and then dried again at 50°C for 3 hours to obtain the desired composite.
Results and discussions
SEM & FTIR
The morphology and structure of the obtained nanocomposite was studied by Scanning electron microscopy (SEM), and the functional groups were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The SEM images of pure PANI and PANI/PS composite are shown in Fig. 1 (a–b). The SEM image of pure PANI doped with HCl shows a predominantly fibrous morphology with fibers of uniform diameter of 93 nm. However, PANI/PS composites show very different morphologies. PANI/PS images show some nanoscale structures where PS are coated on the surface of PANI nanofibril structure. From the SEM images, it is clear that PANI/PS composite shows presence of a large surface area required for adsorption.
Figure 2 shows the FTIR spectra of pure PANI, pure PS and PANI/PS composite. FTIR spectroscopy is a powerful tool for analyzing the molecular structure and the chemical interactions of the constituent polymers. The appearance of new peaks in the composite FTIR spectra along with changes in existing peaks directly indicates the chemical interaction between polymers. The obtained values are in good agreement with theoretical prediction.
Adsorption Tests
Table 1 tabulates the adsorption results of pure PANI and PANI/PS composites. From the results, it is clear that PANI/PS composites show the best removal efficiency because of the presence of high surface area due to its fiber morphology. Therefore, the remaining adsorption studies are done only on PANI/PS composites. The following sections describe the effect of contact time, pH, metal loading and composite dosages of the PANI composites on the removal efficiency of Pb from aqueous solution.
Effect of contact time
The effect of time on the adsorption process of PANI nanocomposite was obtained by plotting the removal efficiency of Pb against time (Fig. 3). For the solution containing 50 ppm of Pb the maximum adsorption was reached in a short period of time and the composite adsorbed approximately 90% of the metal ion. The kinetics of the uptake of metal ion is related to the explicitness of the interaction between the metal ion and the polymer composite matrix.
Effect of pH
The pH of the solutions showed significant effect on the adsorption process. The effect of pH on the adsorption process of nanocomposite is represented in Fig. 4, where the adsorption coefficient was determined over the pH range 2–9, using 0.2 g PANI nanocomposite and 50 ppm Pb solution. It is clear that the maximum adsorption of metal ion took place for the solution with pH 2–6, and decreased at higher pH values. In our study, the pH of the prepared Pb solutions were adjusted to pH 5.
Effect of metal loading
The study of initial metal ion concentration on the sorption characteristics of the polymer nanocomposite is analyzed in the concentration range 30–100 ppm of the metal ion. The adsorption, as it can be seen in Fig. 5, is increasing rapidly with the increase in the initial concentration of Pb until 70 ppm. Beyond this concentration, the rate of increase in the adsorption is slow most probably because the adsorption sites are already saturated.
Effect of composite dosage
Figure 6 illustrates the effect of PANI composites weight on the adsorption of metal ions. Varying amounts (0.1–0.5 g) of sorbent are added in 100 mL 50 ppm Pb solution under optimized conditions. From the graph, it is obvious that as the adsorbent concentration increases the removal efficiency of Pb in PANI/PS composite also increases. This is because the increase in adsorbent concentration provides greater surface area for adsorption and as a result it can hold more metal particles.
Conclusion
This work illustrates the preparation and adsorption property of pure PANI and PANI/PS composites. The synthesis of PANI nanocomposite has been successfully performed by in situ polymerization method and the incorporation of the PANI in PS was confirmed by FTIR. The SEM images of PANI and its composites confirmed the nanometer size range of PANI fibers. Adsorption performance of PANI and its nanocomposites has been studied for the removal of Pb from aqueous solution. Among the two adsorbents, PANI/PS shows 95% removal efficiency. The adsorption capacity of PANI/PS for Pb increases with initial metal concentration and composite dosages. Maximum adsorption was observed for pH 5, hence all the measurements are done at that pH. In conclusion, PANI/PS nanocomposite could be a good candidate for efficient Pb-removal from wastewater and for the deep-purification of pollutant water.
References
[1] S. S Madaeni, Y. Mansourpanah, Filtration & Separation, 40(6) (2003). 41–46.
[2] T. Kurbus, Y. M. Slokar, A. M. Le Marechal, D.B. Voncina, Dyes and Pigments, 58(2), (2003) 171–178.
[3] J. Stejskal, R. G. Gilbert, Polyaniline. Preparation of a conducting polymer, Pure Appl. Chem., 74 (2002) 857–867.
[4] N. Gospodinova, L. Terlemezyan, Conducting polymers prepared by oxidative polymerization: polyaniline, Progress in Polymer Science, 23 (1998) 1443–1484.
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Utilization of Two Microalgae Species, Synechococcus sp. and Cheatoceros sp., for Aquatic Toxicity Assessments in the Qatari Marine Environment
Microalgal bioassays are currently used worldwide to help assess the impacts of contaminants on aquatic ecosystems. Algae are particularly important to such assessments because they represent the basic trophic level of the aquatic food web and contribute to ecosystem biodiversity. Toxicological impacts to these species may have follow-on effects (e.g., depletion of food source) on higher trophic levels and subsequent biodiversity consequences. ExxonMobil Research Qatar in collaboration with Qatar University Environmental Sciences Center and the Ministry of Environment are currently conducting researchto understand the impact of several water borne contaminantsto species of microalgae found in the Qatari marine environment.
The two algal species used in this study included Synechococcus sp. which is a unicellular cyanobacterium that is very widespread in the marine environment and are preferentially found in the upper well–lit surface waters. The other species, Chaetoceros sp. is a centric diatom and is abundantly found in Qatari seawaters. Chaetoceros is a highly diverse diatom genus and has been described as the most dominant phytoplankton group in the ocean, in general. They play an important role in various marine ecosystem as a preferred food source for zooplankton and invertebrate larvae.
Two microalgal species were isolated from the Qatari coastal watersand cultured in the laboratory. The cultures were maintained at 22 ± 1.0°C, under a 14 h:10 h/light:dark cycle provided by cool white fluorescence light (7000 ± 10% lux), in nutrient-enriched synthetic seawater (F/2 medium) at pH 8.0 ± 0.5 and salinity 40 g/L. The effect of abiotic factors such as salinity and temperature on the growth of both species was also investigated during culture development. Salinity effects were studied in therange of 25 to 45%. The results show that both species are euryhaline - that is, able to grow at all tested salinities – with best growth achieved at 30 and 40%. Both species were subsequently tested for tolerance to temperature ranging between 16 to 38°C,at both 30 and 40% salinities. These temperature experiments show that the highest growth rate was observed in cultures at 30°C and salinity 30%. Similar results were obtained at 30°C and salinity 40%. The lowest growth rates were observed at the lowest temperatures, while a decreased rate was also observed at the highest temperature.
Acute (24 hr) and chronic (72 hr) toxicity tests were carried out on both microalgae species, with copper chloride which is widely used as a reference toxicant. Tests were performed using copper chloride at concentrations ranging between 0.05 and 0.75 mg/l. The test endpoints included: cell division rate inhibition, light-scattering properties of algal species, chlorophyll a fluorescence and esterase activity. Results for Synechococcus sp. and Cheatoceros sp. show a dose-dependent response to contaminant exposure. Consequently, it is apparent that both species may be considered as model test species for use in toxicity assessment and serve as akey component in a battery of toxicity tests with other native Qatari marine organisms. In particular, the toleranceof these microalgae species to fluctuations in salinity and temperature make them an ideal species to further explore the impact of potential effects of toxicants in Qatari waters.
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Development of Green Inhibitors to Prevent Hydrates Formation, Protect Environment and Reduce Energy Cost in Oil and Gas Industry
Authors: Mert Atilhan, Fahed Aziz Qureshi, Tausif Altamash, Muhammad Tariq and Majeda KhraishehGas hydrates are identified as ice-liked solid, crystalline compounds having polyhedral water cavities, where gas molecules get trapped during operation under high pressure and low temperature condition. These hydrates have a tendency to completely block the pipelines and can cause major operations shutdown, leading to large economic losses and causing high safety risk in transmission pipelines. Thus, annually the oil and gas sector spends over 100 million US $ on purchase of chemical inhibitors that can help to prevent hydrates formation in subsea lines.
These inhibitors are classified into two separate categories, the thermodynamic and kinetic inhibitors. The thermodynamic inhibitors act by shifting the hydrates formation temperature and the kinetic inhibitors act by shifting the hydrates formation time. Currently, the thermodynamic inhibitors like Methanol and Methylene ethylene glycol (MEG) are mainly used in industry. These inhibitors are highly flammable and cannot be disposed of easily into the environment. They are required in bulk quantities (>30 wt%) and separate facility is needed for their storage and treatment process. This increases the overall energy cost and leads to major environmental disposal issue. Therefore, there is a high demand for inhibitors that are environmentally friendly and cost effective in oil and gas sector.
Ionic liquids (ILs) are salt like compounds that have received attention due to their environmentally friendly, recyclable and non-flammable nature. These ILs have potential to prevent hydrate formation and they can act as both thermodynamic and kinetic inhibitors simultaneously. In this work, the Pyrrolidinium based ILs have been tested as gas hydrate inhibitors and synergistic compounds (Syn) are added with these ILs to improve their overall effectiveness. For the first time, the thermodynamic and kinetic study on ILs has been conducted using high dosage mixture of ILs + Syn on methane rich gas mixture to check their effectiveness in preventing gas hydrates formation.
All the experiments are performed using a high pressure rocking cell assembly supplied by PSL Systemtechnik GmBH, at different pressures ranging from (40 to 120) bars. According to the tests results, we have evaluated that the mixtures were able to prevent hydrates formation by providing a temperature shift of up to 2.2°C at low pressures and by delaying hydrates formation time by (6 to 14) hours.
These results confirm the dual inhibition behaviour of these mixtures, as they were able to shift hydrates formation temperature and delay hydrates formation time simultaneously. The results were also compared with widely known industrial inhibitor methanol and only a difference of 0.5°C was observed. Thus, this research provides an innovative approach towards development of environmentally friendly inhibitors and to reduce energy cost in the oil and gas industry.
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Buildings Construction and Maintenance Role in Urban Pest Management
More LessThe major threats to community health were recognized as coming from poor housing, poor management of sewage and drainage, foul air in industrialized towns, unsafe drinking water, and inadequate control of pests.
Increasing pest infestation in urban areas is now a reality. The reliance on the use of chemical pesticides leads to negative results. Use of clean ecological methods must be the strategy of the future. Pests are attracted to our buildings to satisfy their needs which include food water and shelter. The development of building designs (green buildings), offers intriguing opportunities for use in future urban pest control by preventing pests from invading our buildings and enjoy the available food and shelter.
A survey was conducted including 150 houses in Rayyan municipality with the aim to investigate the buildings defects which play a role in pest infestation. The results revealed that more than 50% of the buildings inspected are having defects which attract urban pests to the buildings. These defects include the presence of unsealed electrical and water pipes entry points to the buildings, sewage water manhole defects, cracks and crevices, gaps between floor tiles, doors and windows gaps. More than 60% of the buildings have defects in sewage water manholes include broken covers, manholes not built according to the standard specifications. More than 90% of the manholes are not equipped with valves. The results also indicated buildings with defects are more likely infested with pests like cockroach and ants. House owners questioner, revealed that, 73% of them believe that chemical control is the best method of control and they don't think that sanitation and maintenance will reduce pests population.
It is clear from the results that construction and maintenance can be used as an important tool in urban pests management by preventing pests entry and survival inside our buildings.
The survey results showed that effective pest management depends on more than just a skillful pest control operator because the conditions that allow the pests to have access to the buildings and satisfy their needs and requirements are under the control of other individuals for examples building designers, electrician, plumbers. Buildings managers, owners residence are also involved in the pests management program because sanitation is a major factor in the pest prevention program.
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Qatar Culture Collection of Microalgae: A Sustainable Source for Biodiesel Production and Omega Fatty Acid Compounds
Authors: Touria Bounnit, Gomza Al Ghazal, Mariam Al Mureikhi, Imen Saadaoui and Hareb Al JabriMicroalgae are photosynthetic microorganisms that can grow in different environments (sea water, fresh water, waste water soil, rocks…) and under various conditions (Light, pH, temperature, salinity…). During their phases of growth, they produce a variety of metabolites such as lipids, proteins and carbohydrates in large amounts over a short period of time. These metabolites can be processed into both biofuels and other useful bioproducts. Microalgal lipids can be converted to biodiesel via process called transesterification. The use of biodiesel will decrease the emission of harmful gases, which can help in reducing the greenhouse effects and global warming. It is nontoxic, biodegradable and has the potential to replace the conventional diesel fuel. The microalgal lipids extract can also constitute a natural source of active compounds offering a variety of nutraceutical and pharmaceutical applications.
In the Algae Technologies Program at Qatar University, a Culture Collection of Cyanobacteria and Microalgae (QUCCCM) has been built and maintained in the liquid nitrogen. This culture collection contains more than 200 strains isolated during different periods of the year and from various places in Qatar. In this work we present the results of 8 marine green algae belonging to 3 different microalgal major groups: Chlorocystis sp., Nannochloris sp and Tetraselmis sp.
The strains collected from different Qatar coastal places were screened for their growth rate, amount of total lipids as well as their Fatty Acid Methyl Ester (FAMEs) profiling. Culture was done in liquid F/2 medium at 300 C for a period of 15 days, after which algae were harvested for the determination of total lipids. A one step transesterification process was used to derivitize the intrinsic lipid into fatty acid methyl esters and the individual components were identified against known standards. The fatty acid profiling was obtained using a GC-FID.
The comparative analysis of the QUCCCM isolates growth rate showed that Nannochloris sp. is the fastest growing isolate with a maximum value of 1.013 day-1. In terms of lipid contents, the results indicate a variety of the amounts. Nannochloris sp. showed the highest amount of total lipid (28.5%) followed by Chlorocystis sp. isolates with a total lipid amount of (19.5–21.5%) and later comes the Tetraselmis sp. strains with a total lipid content of (17.8–20.3%). The GC analysis showed a diverse range of FAMEs produced. All the strains screened contains the important FAMEs suitable for biodiesel production (C14, C16 and C18). The good growth rate of these strains along with their lipid content and profile make them competitive for a viable algal biofuel technology comparing to the terrestrial oil crops which need longer time to grow and present lower amount of lipids (Weyer et al., 2010). In addition, we observed the presence of the omega-3 and 9 long-chain polyunsaturated fatty acids (LC-PUFAs), such as eicosapentaenoic (EPA, 20:5 n-3), docosahexaenoic (DHA, 22:6 n-3) and Nervonic Acid (C24:1 n-9) acids, which have a high commercial value and are known for their beneficial effects on human health.
Microalgae, Lipid, Fatty Acid Methyl Ester, Biodiesel, LC-PUFAs.
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Metagenomic Approach to Explore Microbial Communities in the Rhizosphere of Date Palm
Authors: Ali El Kharbotly, Noha El Badawy, Maria Torres, Imene Mattat, Ameena Al-Malki and Mohammed HassaneinMicrobial communities in the date palm rhizoshere can play a vital role in the development of the palm and its health. Using the metagenomic as a tool can help in exploring these microbial communities in searching for microorganisms with potential for agricultural practices.
Samples (roots and soil) were collected for metagenomic analysis from 12 date palms (khalas cv) growing at Roudat Alfars Research Farm of the Ministry of Environment. Sampling were done for the second time three month after fertilization of the palms. DNA was extracted and PCR were carried out for the variable regoins v1-v3 of the 16S rRNA gene. The amplified fragment were sequences using Next-Generation Sequencing (NGS) in two directing. Assembly of the reads and analysis were done Using mothur software Version 1.36.1.
Results showed the presence of 13 bacterial phyla. Fertilizer has positive effect on increasing the presence of most of these phyla. A strong presence of cyanobacteria were observed followed by Proteobacteria then Actinobacteria in most samples. Cyanobacteria showed dramatic increased (in some samples more than 60 %) after fertilization. Cyanobacteria is known of their potential for atmospheric nitrogen fixation to ammonia (NH3), nitrite (NO2) or nitrates (NO3). Such process can act as an additional source of nitrogen for date palms.
Also the analysis reviles the presence of Arthrobacter which is one of the main components of the soil microbes. It has the potential to reduce hexavalent chromium level in contaminated soil as well as degrades the 4-chlrophenol. Further investigation is needed to assess their potential as biodegradation agent.
The following step is to isolate and characterize these bacteria as well repeating the metagenomics analysis after one year to determine the persistence of these microbial communities in the date palm orchard.
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Modeling Risks of Urban Heat Island (UHIs) and Microclimate Change in Doha City Using Geoinformatics
Authors: Mooza Saqr Almohannad and Yasir Elginaid MohieldeenThe economic boom that has taken place in Qatar in the last few decades has resulted in rapid population growth, urban expansion and change in life-style. Qatar Gross Domestic Product (GDP) has increased from 5.05 billion USD in 1986 to 211.8 billion USD in 2014. At the same time population has increased from 0.4 million in 1986 to 2.17 million in 2014. Urban expansion was and the accompanied modern urban life-style was necessary to accommodate this rapid population increase. Doha City has had the biggest share of urban expansion in the country.
Recently, Doha faced a huge urban development and urban expansion in a short period of time. The modern urban designs in the city and the material used in the construction have changed the land surface albedo and the Land Surface Temperature (LST) in city. With this urban expansion, the Urban Heat Island phenomenon has become more noticeable between the urban center and the suburbs. Changing of landscape in the city due to the construction of roads and buildings has increased the surface temperature, as paving and building material replaces the Earth's natural surface causing surface compactness. Surfaces that were once pervious moist have become impermeable and dry. Open land and vegetation are replaced by buildings, roads, and other infrastructures and surfaces with high heat capacity, which impacted and created microclimates. This impact is due to the fact that many surfaces and asphalt absorb heat during the day and releases it during the night.
Anthropogenic heat is one of the main causes of UHI in cities. The main sources of this heat include cooling and heating buildings, industrial processes, and transportation (highways, airports,..etc). Other causes of UHI are: air pollution; surface waterproofing; thermal properties of fabrics; and surface geometry.
Urban heat island and temperature increase have a negative impact on the environment and on human health. Increased temperature also increases energy demand, air pollution and water shortages.
This study uses remotely sensed data (high resolution satellite images) to highlight the urban expansion in Doha and the expansion of the UHI phenomenon as the city expands. Multi-date images from Enhanced Thematic Mapper (ETM) sensor on board Landsat Satellite were classified using supervised and un-supervised classification techniques to accurately identify and map the urban expansion in Doha. The classification results were verified and tested. Support Vector Machine supervised classification provided the most accurate classification of urban areas.
In addition to the classification of the images, Thermal Bands of the same Landsat ETM images were modeled to calculate LST images for Qatar using Planck's function:
T = K_2/In([K1*ϵ]/[CV]_R1+1)
Where: T is degrees Kelvin
K1 & K2 are satellite sensor constants obtained from the image metadata
CVR1 is cell value as radiance
ϵ_is emissivity (typically 0.95)
The LST images show higher LST in the urban areas than in the desert suburbs by considerable margins especially in compacted areas, such as asphaltic roads and airports.
This study also looked at the changes of urban fabrics over time and their land surface temperature Varian's in Doha. These variations in LST within the city and between the city and the desert suburbs create microclimates. These LST images could be used for the identification of different micro-climates within Doha. This micro-climates identification is very important to town planners, The results could also be used for air quality, solar energy and land-use planning studies.
This study made some recommendations on how to reduce the UHI and increase in temperature phenomena by introducing Green Building technologies and green positive road network, and the interlocution of more green spaces in the cities.
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Enhancing the Remediation Capacity of Mercury Ions from Fluorescent Lamp Using Roasted Date Pits and Its Modified Forms
One of the most toxic heavy metals in the environment is mercury (Hg). However, it still has major uses in various industrial and agricultural applications; leading to localized mercury pollution. There has been an increase in the number of used fluorescent lamps compared to incandescent bulbs. Mercury is being used in fluorescent lamps in the elemental form where it can be vaporized under high pressure. The elemental form of mercury is also lipid soluble and can pass through both brain barrier and the placenta which can cause neurological disorder. Due to its harmful effect, the spent fluorescent lamps (SFLs) are being classified as hazardous wastes where mercury may leach and contaminate soil and groundwater. For these reasons the fluorescent lamps should be treated to reduce potential Hg toxicity or to use other components after recycling; e.g. glass and aluminum cap.
Various extraction methods are available in the literature. However, in this project, two methods of extracting mercury from SFL were performed to assess their efficiency: acid extraction and microwave digestion. It was shown that the acid extraction only, using different acids ratios, were not able to remove all mercury from phosphor powder. However, the combination of acid extraction with a microwave digestion enhanced the efficiency of mercury extraction by more than 90%.
Physicochemical treatment such as adsorption is also viewed as one of the easiest, safest, adaptable, and cost-effective physical chemical treatment methodologies in remediating toxic metals from aqueous medium. Though, the growing costs and environmental concerns linked with the commercial adsorbents has steered a new research orientation, which intended at developing low cost adsorbents that are produced from waste materials which are natural and renewable resources. Date pits as agricultural waste materials have been effectively employed as an adsorbent for remediating various heavy metals from aqueous media and normally with the benefits of being low cost, naturally available, and environmentally friendly. Chemical modifications processes were also be employed to improve their remediation capacity and selectivity.
The current study, therefore, investigated the effect of different modification treatments on the roasted date pits (RODPs) surface chemistry and therefore; enhancing the mercury remediation capacity. The RODPs was grafted with organosilane to remediate Hg2? from the extracted fluorescent lamp solution. The remediation of Hg2? from the extracted fluorescent lamp solution was investigated in a batch isotherm remediation system pertaining to pH, concentration, particle sizes, and contact time.
The SFLs of different brands were collected from throughout Qatar. Two main types of SFLs were collected and tested; the T8 and T12. The SFL were scratched and the powder inside was carefully collected by brushing the inside of the lamps (approximately 100 g have been collected). Various reagents and materials were used for the mercury extraction experiments such as HCl, HNO3, and H2O2. The instruments and methods mainly adapted in these experiments were Cold Vapor Atomic Absorption Spectrophotometer (CVAAS) for the mercury analysis, incubator shaker to maintain constant shaking with temperature, microwave for the extraction enhancement, and oven. In the experiments, the ratios of HCl, HNO3, and H2O2 as extracting agents were carefully chosen to achieve the maximum exactable mercury.
The collected date pits were roasted at 150°C for 5 h and the sulfur-modified roasted date pits was carried out to investigate the adsorption enhancement after modification. In order to study the impacts of different pH values on the adsorption, the FTIR spectra of the RODP and RODP at different pH values were recorded. The FTIR measurements were performed over 4000-400/cm. Scanning electron microscope (SEM) was also used to evaluate the surface morphology of the adsorbents using the JEOL model JSM-6390LV.
After determining Hg2+ concentration in the extracted SFL solutions, various initial Hg2? concentrations were prepared. The residual Hg2+ in solution was analyzed after adsorption onto RODP. Different key parameters will also be performed such as the effect of pH, mass, and the solution temperature.
From the initial results, we can conclude that the highest Hg adsorption occurred at pH 6 with almost 80% adsorption value. Moreover, at pH 8 and pH 10, the adsorption decreased with an average Hg concentration of 3.5 and 8.01 ppm, respectively. This decreasing in the adsorption capacity is due to the formation of mercury (II) hydroxide Hg(OH2) which forms a precipitation; resulting in decreasing the adsorption. However, pH 2 and pH 4, have average concentration of mercury equal to 18.8 and 18.3 ppm, respectively, which is very high concentration and it is over range.
From the FTIR results we can determine the functional groups of the RODP which can determine the reactivity of the RODP towards mercury. According to the results obtained from CVAAS that pH 6 is the best pH for the adsorption process, functional groups found in the RODP having pH 6 are mainly hydroxyl and carboxyl acid which means that these functional groups have the highest ability to adsorb mercury more than other groups. Acknowledgement: This paper was made possible by UREP grant # (UREP17-066-1-004) from the Qatar national research fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the author(s).
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A Novel Forward Osmosis Desalination Process for Irrigation and Industrial Purposes
Authors: Adel Obaid Sharif and Maryam M. AryafarThe availability of clean water for agriculture has become a growing concern because of the increasing global water scarcity. Agriculture sector already accounts for around 70% of the total water withdrawals in the world whereas domestic and industrial water use is about 10% and 21% respectively. Desalinated water has high quality and irrigating with desalinated water would result in 24% increase in the crop yield and assist a 45% reduction in the current water irrigation volume simultaneously. However desalination is an energy intensive process and an expensive option. The current membrane and thermal desalination systems have many limitations, including high energy consumption and capital cost, especially for thermal methods, coupled with negative environmental impacts due to the discharge of brines and chemicals. Forward Osmosis (FO) promises to overcome most of the practical difficulties in conventional RO desalination process such as fouling, scaling, chemical treatment and high power consumption. In addition, FO process gives higher throughput with minimal environmental impact including minimal chemical additives and rejection of waste stream. Forward Osmosis (FO) process has the potential to increase the availability of freshwater both in coastal areas with limited resources and in areas where seawater, salinized groundwater and municipal wastewater are available. The novelty of FO process lies in using natural osmosis as a driving force for water to move across a semi-pearmeable membrane from a solution of low osmotic pressure (seawater) to a solution of high osmotic pressure (DS). The choice of draw solution (DS) has a large impact on the performance and viability of the FO process. The draw solutes should be able to generate high osmotic pressures and be completely regenerated using simple and energy efficient techniques.
This study presents a novel FO process for producing irrigation water using thermolytic draw solution. The main energy intensive stage in FO process is the separation of draw solute from the freshwater. In this research, the concept of employing liquefied gas compounds as a draw agent has been investigated among 137 gaseous compounds by determining their high solubility in water. In this process a liquefied gas as DS with high solubility in water resulting high osmotic pressure has been used. The DS could be separated from water by changing the operating temperature and or pressure allowing for an efficient and complete removal of the DS. The modified FO process operates at low hydraulic pressure
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The Indigenous Qatari Marine Copepod, Euterpina Acutifrons: A Promising Marine Invertebrate Model Organism for Aquatic Eco-Toxicological Studies
Authors: Nandita Deb, Suhur Saeed, Sarah Bacha, Christopher Warren and Jennifer DupontAn important objective of aquatic toxicological assessments is to evaluate the effects of water-borne toxic compounds on organisms which play a crucial role in aquatic communities. In marine ecosystems, copepods have a major impact on essential ecological processes: they exert grazing pressure on phytoplankton, and are a significant food source for several fish and macro crustaceans. Euterpina acutifrons, a harpacticoid copepod, is an abundant species in the Arabian Gulf, including the coast of Qatari peninsula. Its high content of poly unsaturated fatty acids make it a nutritionally superior live feed for larval fish in aquaculture, an industry developing fast in Qatar. With its ubiquitous distribution worldwide, inter-and intra-sexual dimorphism, well-defined life cycle, short generation time, and anamorphic developmental stages, this species meets many of the criteria to become a suitable model for toxicity studies. The present study defines protocols for establishing a successful laboratory culture of Euterpina acutifrons and for its acute toxicity testing with four toxicants. This study will add to the refinement of a suite of bioassay techniques being developed at ExxonMobil Research Qatar using a gamut of vertebrate and invertebrate indigenous marine species.
A sustainable culture of Euterpina acutifrons was established by rearing ovigerous individuals of this native species isolated from local waters. A few gravid individuals were used to include the natural genetic variability in the population. Through a series of planned trials, a simple protocol was established for culturing and maintaining the species in the laboratory. A temperature of 22 ± 2°C, photoperiod of 12 h light: 12 h darkness, salinity at 40 ± 2 ppt, and a 3:1 microalgal mixture of Chaetoceros sp. (diatom) and Synechococcus sp. (blue-green algae) as food, fed twice every week, was found to give an optimum survival and fecundity in the laboratory.
In order to investigate the efficacy of this species as a ecotoxicity test organism, a series of static, acute 24 h and 48 h toxicity tests were performed using three widely used reference toxicants, sodium dodecyl sulfate (SDS, an anionic surfactant used widely in cleaning and hygiene products), 3, 4-dichloroaniline (DCA, a metabolite of several herbicides), and Zinc (heavy metal) at 22 ± 2°C. Impact of chlorine, an anti-biofouling agent used in industrial cooling waters globally, was tested in a semi-static set up, where chlorine dose was renewed at regular intervals. Similar-sized copepodite stages used for these tests were procured through laboratory culture synchronization. The 24 h/48 h LC50 values were calculated based on the end point of the tests, which was mortality or total cessation of mobility. The copepod showed dose-dependent responses and different sensitivity towards the four toxicants; toxicity ranking increasing from DCA, SDS, Zinc to Chlorine. The differences in toxicities can be attributed to different mechanisms of action of the four compounds. The sensitivity of this species compared favorably with other established marine invertebrate models for ecotoxicity testing. Given, the feasibility of culturing, continuous egg production throughout the year, and high reproducibility of the toxicity responses in this study, it is advocated to further explore the use of Euterpina acutifrons as a model organism to assess long- and short-term effects of potential water-borne contaminants in the Arabian Gulf.
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Environmental Factors Affecting the Growth and Enzymatic Activity of Ceratocystis Radicicolathe Causal Agent of Black Scorch Disease on Date Palm
Authors: Fatima Al-Naemi, Talaat Ahmed, Osman Radwan and Sara Al-HadidiBackground: Ceratocystis radicicola is a soil-borne pathogen (Wingfield et al, 1993) causing sudden death of date palm (Phoenix dactylifera) in USA and South Africa (Bliss, 1941; Lind & Smit, 1999). It also has been reported to be associated with date palm in Qatar causing black scorch disease (Al-Naemi et al., 2014). Environmental factors such as poor hygienic conditions, stressed palms or senescent tree parts contribute to increase the incidence of black scorch in date palm (Laville, 1966).
Plant pathogens including fungi produce variety of enzymes that degrade plant cell wall. Fungi also secrete several molecular forms of hydrolases that attack the same substrate although they are different in isoelectric point and molecular weight. Extracellular enzymes secreted by fungi are able to macerate tissues and degrade cell wall components. Consequently, they must contain all enzymes related to the types of glycosidic linkages that are present in cell wall polysaccharides. The level of these enzyme activities correlates with the development of disease symptoms (Riou C et al., 1991). Objectives: This study aimed to: (i) examine the influence of salinity and drought stresses on the growth of C. radicicola in vitro; (ii) study the enzymatic activities of xylanase, cellulase and pectinase in C. radicicola, (iii) examine the effect of various Carbon sources (sucrose, xylan, carboxymethyl cellulose and pectin) on C. radicicola enzyme activities; and (iv) investigate the effect of pH media on the fungal growth. Methods: For salt stress, 4 mm disc of C. radicicola was cultured in PDA or PDB media with different concentrations of NaCl (0, 0.26, 0.43, 0.60, 0.86, 1.03, 1.20 and 1.37 M). The culture was incubated at 25°C for 7–21 days under dark conditions. Rate of relative fungal growth on PDA was recorded and given the following scales (–: No growth, 1+ very minimal growth, 2+: minimal growth, 3+: moderate growth, 4+: heavy growth and 5+: very heavy growth). The mate of fungal growth on PDB was harvested every weak and fresh and dry weight obtained. Hemocytometer was used for spore counting and the number of spores is divided by 5 and multiple to 104 to obtain the total number of spores/ml.
For drought stress, 4 mm disc of C. radicicola was cultured in PDA and PDB media with different percentages (0, 2, 4, 6, 8, 10, 20, 40 and 60%) of Poly Ethylene Glycol (PEG4400). The culture was incubated at 25°C for 8–10 days under dark conditions. The diameter of fungal growth on PDA was measured. The mate of fungal growth on PDB was harvested. Spores were counted by using hemocytometer.
In case of enzyme activity assay, Czapek media was prepared where the carbon source was substituted with 1% of the following: carboxymethyl cellulose (CMC), sucrose, pectin or xylan. To optimize the fungus growth, pH media was adjusted at different levels (5.5, 6, 6.5, 7, 7.5 and 8). In addition, standard Czapek broth media was used as a control. Four mm discs of C. radicicola were inoculated in czapek media and incubated at 25°C for 8–10 day. Cultures were centrifuged at 5000 rpm for 20 min. and supernatants were used to examine xylanase, cellulase and pectinase DNS – enzymatic activities. The enzymatic activity was calculated using the following equation; Enzyme activity = (standard factor × absorbance)/time of incubation (min); whereas standard factor = (concentration (m mol/ml) of standard/absorbance at 540) × dilution factor. Spectrophotometer was used to measure the enzyme activity based on reduced sugar in the media. Results: Results from salinity stress in vitro showed a clear growth of C. radicicola in PDB media with NaCl concentrations of 0.26, 0.43, 0.6, 0.86, 1.03 and 1.2 M during the first three weeks while no growth was occurred in PDB with 1.37 M. Radial growth of C. radicicola did not show any changes on PDA with 0.26, 0.43 and 0.6 M while fungal growth diameter decreased significantly under 0.86, 1.03 and 1.2 M concentrations to reach 4.9, 2.3 and 1.4 cm, respectively (Fig. 1). Number of spores was decreased by increasing NaCl concentrations from 1.4 × 104 in control treatments to reach zero in 1.2 M.
Growth of C. radicicola was tested under physiological drought stress using different concentrations of PEG4400 (0, 2, 4, 6, 8, 10, 20, 40 and 60%). C. radicicola was able to survive under drought stress regimes up to 40% in the first seven days while it failed to grow at 60% of PEG4400.
Results of enzymatic activity assays showed that C. radicicola grow very well in czapek media supplemented with 1% both xylan and pectin as carbon sources while it showed weak growth in czapek media supplemented with 1% of CMC. On the other hand, C. radicicola did not grow in czapek media supplemented with 1% sucrose. Results also showed that both Xylanase and carboxymethyl cellulase had the highest enzymatic activities with 109 and 6.8 IU/ml, respectively when pectin was used as a carbon source at pH 8. Moreover, high pectinase activity was recorded (61 IU/ml) when pectin was used in the growth media at pH 7.5. When xylan was used as source of carbon, Xylanase showed high activity at pH 5. In standard czapek broth media, activities of xylanase and carboxymethyl cellulase enzymes increased by increasing pH while pectinase activity decreased. Conclusions: To study the effects of salinity and drought stresses on the growth of C. radicicola in vitro, the fungus was exposed to different salt and drought stress conditions. Our results revealed that C. radicicola was able to survive and grow up to 1.2 M NaCl during the first three weeks, while it could not grow at 1.37 M. Fungal growth diameter and number of spores were decreased by increasing NaCl concentration. Growth of C. radicicola was affected severly under physiological drought stress where it was not able to survive at 60% of PEG4400. Enzymatic activity assays showed that C. radicicola grow very well in czapek media supplemented with 1% both xylan and pectin as carbon sources while it showed weak growth in czapek media supplemented with 1% of CMC. On the other hand, C.radicicola did not grow in czapek media supplemented with 1% sucrose. Xylanase and carboxymethyl cellulase had the highest enzymatic activities when pectin was used as a carbon source at pH 8.
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Vibration wave characteristics in Conventional and Periodic Drill string models
Authors: Fesmi Abdul Majeed and Sadok SassiDrill string models are of two major types- Conventional and Periodic. Conventional drill string models are widely used due to their simplicity in manufacturing and dynamics analysis. Drill strings are affected mainly by torsional, lateral and axial vibrations. The dispersive or propagative nature of these vibrations can only be analyzed by using periodic drill string models. Drill pipe makes up the majority of the drill string. In reality, at each end of the drill pipe, tubular, larger-diameter portions called the tool joints are located. Since the dimensions of the tool joint are negligible when compared to the drill pipe, conventional drill string models assume drill strings to be uniform structures. The tool joints in drill strings introduce a geometrical periodicity in the structure.
A periodic structural component is comprised of a repeating array of cells, which are themselves an assembly of elements. The elements may have differing material properties as well as geometric variations. The periodic structures act as mechanical filters for the wave propagation. A material or geometrical change in the structure causes a disruption to the continuous propagation of vibration waves.
There are three types of waves propagating in rotating structures: torsional, flexural (bending) and longitudinal. Of these waves, torsional and longitudinal waves are dispersive while flexural waves are non- dispersive. The proportions of the waves which are dispersed vary according to the Wavenumber. The wavenumber is a property of the wave and depends on the structural, material and geometrical properties of the wave guide. Waveguide is the medium through which a wave travels. The wave number, and hence the dispersion and propagation characteristics of waves can be tuned by varying the material and geometrical periodicity in the drill strings.
This paper presents the vibration propagation and attenuation characteristics in conventional and periodic drill string models. The periodic drill string model is developed such that it can be easily scaled to a real drilling rig model. The research also features a laboratory setting which comprises a mini drilling rig and actual drilling samples. These features ensure robustness of the dynamics analyzed for the periodic drill string model.
The research findings are analyzed under zero and non- zero borehole drill string interactions. Vibration information is collected from upper and lower parts of the drill string models to compare the propagation and attenuation characteristics. Proximity sensors are used for the data acquisition which is then analyzed using frequency and power spectrum graphs. The time and frequency domain vibration propagation characteristics are investigated for both the conventional and periodic drill string models. Laboratory testing analyzes (1) introduction of stop and pass band regions in frequency spectra by periodic drill string models, and (2) vibration attenuation in torsional and lateral vibration modes. The tests confirm the introduction of stop bands in frequency spectra for the periodic drill strings, while they were absent and had an all pass-band for conventional drill string models.
The research opens up a new method of passive control of drilling vibrations- by introducing tool joint designs which could be tuned to efficiently dampen out the harmful vibrations affecting the drilling rigs.
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Experiences and First Results from the EC Product Environmental Footprint (PEF) Pilot on Hot and Cold Water Supply Piping Systems in the Building
Authors: Carolin Spirinckx, Karolien Peeters and Mihaela ThuringBackground: The European Commission's Single Market for Green Products initiative proposes a set of actions to overcome the problems companies and consumers face with the diverse amount of environmental information and methods available on the market. Amongst the proposed actions are the establishment of a Product Environmental Footprint (PEF) methodology and a three year Pilot phase to develop product specific rules through a multi-stakeholder process. The aim of proposing the EU-wide PEF methodology is to measure the environmental performance of products and to encourage Member States and the private sector to take them up. VITO is involved in three building related pilots: hot and cold water supply piping systems in buildings, insulation materials used in buildings and metal sheets applied in buildings. In 2017 the Commission will make an in-depth evaluation of the results of this three-year testing period and the results of additional actions related to communication and recommendations. Based on this evaluation, the Commission will decide on further policy applications of the PEF methodology.
PEF pilot on hot and cold water supply piping systems in the building
The Pilot on hot and cold water supply piping systems, submitted by The European Plastic Pipes and Fittings Association (TEPPFA), the European Copper Institute (ECI), the Flemish Institute for Technological Research (VITO), the European Association of Plastics Manufacturers (PlasticsEurope) and the Plastics Recyclers Europe (PRE) is one of the Pilots accepted by the Commission for the three-years testing PEF Pilot phase. During the Pilot phase Product Environmental Footprint Category Rules (PEFCR) for hot and cold water supply piping systems need to be developed. The PEFCR helps directing the focus of future PEF studies on hot and cold water supply piping systems to the most important parameters, thus also reducing time, efforts and costs. To foster the development of a PEFCR, PEF screening studies have been carried out. The representative product used in these screening studies is a virtual product based on the market shares of PEX (cross-linked polyethylene), Multilayer (Polymer/Aluminium/Polymer) and Copper hot and cold water supply piping systems. The weighted PEF environmental profile shows that the most relevant life cycle stages, having a contribution of >10%, are the acquisition and pre-processing of the raw materials for pipes, fittings and other components, manufacturing of pipes together with the ‘end-of-life treatment’. Based on expert knowledge it has been decided to consider as important also the life cycle stages related to the manufacturing of the fittings.
The PEF screening studies looked at 15 different life cycle impact categories. After normalisation of the results, the categories resource depletion (mineral, fossil), resource depletion water and human toxicity cancer effects are found to be the most important impact categories for the hot and cold water supply systems. Besides the above conclusions, the screening studies revealed that publicly available datasets for many processes and materials are missing. Moreover, the available data are often of poor quality which influences the outcome of the study. Also taking into account or not level III toxicity substances influences the outcome of the screening studies.
Currently PEF supporting studies are performed together with specific producers of PEX, Multilayer and Copper piping systems for hot and cold water supply in the buildings. The PEF supporting studies needs to be compliant with any specific requirement included in the draft PEFCR that has been developed, comprising all environmental impact categories and having a full coverage in terms of life cycle stages and processes. The PEF supporting studies are based on existing products as currently sold in the European market. The goal of the PEF supporting studies is to support evidence to the PEFCR development and the intended audience. The studies will be carried out under the assumption that the result will be used to contribute to the development of a PEFCR that could support comparisons or comparative assertions intended to be disclosed to the public. The results of these studies will be used to test the pertinence and implementability of the draft PEFCR including, but not limited to, the identified most relevant environmental impacts, issues related to data collection and quality, verification requirements. Moreover, the uncertainty analysis carried out on the results of the the PEF supporting studies may contribute to the identification of appropriate performance classes (where relevant and appropriate).
Presentation at the ARC conference 2016
The presentation at the ARC 2016 conference will focus on the results of testing the PEF methodology as published by the EC in 2013, step by step. In addition the presentation will illustrate the application of the methodology and illustrate the assessment results of the screening studies. By March 2016 when the ARC 2016 conference will take place, it is expected that the first results of the supporting studies will be ready, so that we can also present first results on the outcome of these studies.
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Preliminary investigations into the reproductive biology, in vitro fertilization and laboratory culturing of the Qatari Pearl Oyster (Pinctada radiata)
By Suhur SaeedThe marine species Pinctada radiata is the most abundant pearl oyster found in Qatari waters; however, little is known about its reproductive biology, ecological importance and life cycle. This species has been harvested for many centuries primarily for natural pearls but also for edible flesh and lustrous shell. Wild stocks of P. radiata are now significantly threatened in the Arabian Gulf region as a result of both natural (e.g. extreme salinity, high temperatures, high evaporation rates and low flushing rates) and anthropogenic factors (e.g. rapid development of coastline areas, overfishing and heavy exploitation). Nonetheless, pearl oysters are a dominant component of the benthic community of the Qatari Coastal waters and are important ecologically as suspension feeders, as food and habitat for other animals, and as structural components of the substratum. Oysters filter prodigious volumes of water, capturing particles down to 5 microns in size and ingesting algae, zooplankton, bacteria and detritus. They are therefore exposed to both dissolved and suspended contaminants. Consequently, they are likely to be excellent indicators of potential contaminants in the Arabian Gulf and can be used for risk assessment and monitoring as part of an effective environmental management program.
Prior to using the pearl oysters in toxicity testing, we investigated the reproductive biology of P. radiata and its in vitro fertilization. The oysters were collected from intertidal habitat at the Qatari coast and cultured in flow-through systems at a density of 2-3 oysters/L. They were divided into three equal groups and were placed every day into a feeding tank for 2 hours. One group was fed with a combination of two microalgae species and rice powder, the second group was fed the microalgae alone and the third group was fed rice alone. After 30 days, 3 oysters were taken from each group to check if maturation was achieved. Eggs from mature individuals were kept in different concentrations of ammonia solution for up to 2 hours to prime them for fertilization. Next, matured eggs and sperms were mixed at different ratios. The fertilized embryos were kept at 27°C and salinity of 40 PSU. Embryo development was followed under a light microscope.
Successful fertilization was achieved with gametes obtained from oysters fed with mixtures of algae and rice (80%), rice alone (60%) and microalgae alone (20%). Fertilization occurred in treatments with 2% ammonia solution and a ratio of 8000:2000 sperm: egg. All stages of larval development were identified (in time) and noted for protocol development. Early development followed the typical marine bivalve pattern of trochophore, D-stage veliger, umbo stage, eye-spot stage, pediveliger, metamorphosis and newly settled spat. This took 3–4 weeks in total, depending on culture condition and food types. The successful in vitro culture and fertilization can provide both embryos and adults which can be used as indicator species to carry out toxicity studies. Future work will focus on examining the sensitivity of the P. radiata to contaminants of concern in the Arabian Gulf region. These efforts are important for assessing environmental risk in the Arabian Gulf and providing science-based tools for making management decisions.
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Will Reverse Osmosis Replace Thermal Desalination in GCC Region
More LessDesalination is probably the only means for fresh water supply to countries in decertified climate. The majority of GCC counties rely on desalinated water for fresh water supply to major cities. Over 70% of the desalinated water in the GCC comes from thermal desalination plants including Multi Stage Flash (MSF) and Multi Effect Distillation (MED). The new trend in the desalination plant in the GCC is 30% Reverse Osmosis (RO) and 70% thermal. However, these percentages vary from one to another country depending on feed water quality and expertise. For example, Oman Sea has lower salinity than the Gulf water and hence Oman uses more RO for desalination than MED and MSF. This decision is also driven by economy as RO process less energy intensive and hence the produced water is less expensive as compared to thermal plants. On the contrary, Qatar and Kuwait use more MSF followed by MED due to the high salinity and low quality feed water. This is also because trials of RO in both Qatar and Kuwait were not successful because of the problems of membrane fouling and restrict pre-treatment requirements due to the quality of the water intake.
The advantages of RO over thermal technologies are well known in terms of lower energy consumption and the cost of produced water; but are not yet taken advantage of in the GCC zone. One of the reasons is blamed on high feed water salinity and bad water quality; other reasons such as lack of experience, red tides and reliability are contributed to the dominance of thermal plants. However, field experience showed that good pretreatment and optimized RO design may overcome the problems of high feed salinity and bad water quality. Several RO plants, such as Fujairah in UAE, are good examples of a working RO technology in the harsh water environment. Good RO design includes design and optimization of both pretreatment and post-treatment. Field experience showed that most of RO plants failure was due to inefficient pretreatment which resulted in providing low quality water to the RO membrane that caused fouling. Fouling, including biological and scaling, can be handled once an efficient pretreatment process is available. Recent advances in pre-treatment techniques include the combination of Forward Osmosis (FO) with RO among other methods. Recent studies by the authors including commercial implantations have shown that the combination of FO with RO addresses the most technical challenge of RO process and that is fouling, which results in lower energy consumption and less chemical additives. Experience showed fouling in FO process in reversible, i.e. can be removed by backlashing while fouling in conventional RO process is irreversible.
In this study, the feasibility of integrating FO with RO process for the desalting of the Gulf water in Qatar is presented. The results are expressed in terms of specific energy consumption, process recovery, produced water quality, chemical additives and overall process cost.
The implementation of RO for desalination is not only reducing the cost of desalination but also the environmental impact. More R&D should be done to provide useful data about RO application and suitability for the Gulf water. The R&D should be focused on laboratory to market development of RO technology using rigorous lab scale and pilot plant testing program.
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A New Class of Electrocatalyst Materials for Direct Methanol Fuel Cell Applications
Authors: Syed M. Javaid Zaidi, Amir Al-Ahmed and Mukhtar BelloDirect methanol fuel cell (DMFC) has been attracting lots of attention as a power source for transportation, stationary and portable electronic devices due to the high energy density of methanol and ease of handling compared to gaseous fuels such as hydrogen and natural gas. However, the commercialization of DMFC is still limited due to some technical challenges such as methanol crossover and low methanol electro-oxidation kinetics. In order for fuel cells to be a feasible and viable option amongst clean energy technologies, innovations in the materials developments are required for efficient operation of fuel cells. Many efforts have been made in various research laboratories to develop high-performance catalysts that will enhance the methanol electro-oxidation. Compared to any single-metal catalyst, Pt has shown the highest activity for the electro-oxidation of methanol in an acid environment. However, Pt is expensive and during the methanol electro-oxidation reaction, COads and other organic intermediates such as formaldehyde, formic acid and methyl formate are formed on the Pt surface, which results in poisoning of the Pt catalyst.
Many binary and ternary catalysts for methanol electro-oxidation have been investigated and reported in the literature, most of them based on modification of Pt with some other metal(s). The aim is to accelerate the oxidation of the intermediates and decrease their accumulation so as to improve the catalyst performance. Among the various catalyst formulations, PtRu alloy has shown the best results for the methanol electro-oxidation. Diverse methods have been used to prepare the PtRu-based catalysts for methanol electro-oxidation. Catalyst composition and method of preparation are known to immensely affect the physical property es and electrochemical performance of a catalyst. Thus, there is the need to use a carefully selected approach in order to prepare a catalyst with the highest attainable performance. Incorporation of transition metals into the PtRu catalysts to form ternary catalysts in order to improve the performance of the PtRu catalysts is one of the techniques attracting a lot of interest. In this work, a novel approach have been used for synthesizing a new class of electrocatalyst nanomaterials for electro-oxidation of methanol by incorporation nano-oxides of transition metals. The prepared nanomaterial catalysts were characterized using FESEM, BET surface area, EDX, FT-IR and XRD. The catalysts performance was studied using cyclic voltammetry and compared with the commercial Pt-Ru/C.
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First Impact Assessment of Genotoxic Components in the Qatari Marine Environment
The Arabian Gulf is a semi-enclosed sea with very high evaporation and low discharge rates resulting in extreme saline and thermal conditions. Additionally the system is characterized by a weak hydrodynamic flushing resulting in pollutant build-up over time. As a result, compared to open marine systems, added stress imposed by pollutants is likely to have severe consequences.
Qatar has witnessed a rapid expansion in coastal development, linked to its industrial and population growth in recent decades. While economically and socially valuable, the growth comes with an associated environmental cost and Qatar's marine environment now faces many pressures including eutrophication, inputs of domestic sewage, discharge of industrial waste and the resuspension of sediment due to coastal construction. Although the threats pose to biota inhabiting Qatar's marine environment are evident, their extent has yet to be fully assessed.
A large percentage of contaminants in the aquatic environment consist of potentially (directly or indirectly) genotoxic, carcinogenic and mutagenic substances. A genotoxin can modify the genetic material at non lethal and non cytotoxic concentrations and has often belated effects which are significantly important at the population and community levels. Genotoxins have particularly high ecotoxicological relevance in situations of chronic exposure to low doses and to multiple contaminants (e.g. in case of PAHs rich tarballs arriving in the shorelines), raising he need to establish genotoxicological profiles of the ecosystems.
Indeed several regulatory developments such as: EU – Marine Strategy Framework Directive, the or US – Environmental Protection Agency – Integrated Risk Information System have stressed explicitly on the need of the detection and assessment of potential carcinogenic and mutagenic toxicants using genotoxicity endpoints.
The analysis of cytogenetic endpoints in organisms exposed to contaminants in their natural environment contributes significantly to the early detection of genotoxic damage. The relevance of cytogenetic parameters and atypical cytogenetic features, such as numerical chromosomal abnormalities, i.e. aneuploidy, have largely proven their relevance as alerting indicators of poor environmental health and relevant biomarkers for the early detection of environmental stressors.
The use of marine invertebrates for in situ environmental assessment is a widely accepted method for identifying risks to the ecosystems. Moreover, at the DNA and chromosome levels they express qualitatively similar types of induced damage to that found in higher organism (e.g. numerical and structural chromosomal aberrations).
In this study, we aimed to take a step towards Qatar's marine sustainability by assessing the health status of the marine environment, and providing early alerting symptoms of degradation, by having as specific objectives: i) to measure the levels, in abiotic (water, sediments) and a marine invertebrate model species, of various anthropogenic contaminants (metals, polycyclic aromatic hydrocarbons, (PAHs) and Total polyaromatic hydrocarbons (TPH) at 3 selected sites around the Qatari coast, ii) measure the biological response at the chromosome level, and iii) determine the main drivers of genotoxicity through a multivariate analysis in order to establish a first partial genotoxicological profile of the Qatar Marine Zone.
The 3 selected sampling sites, with expected different levels and sources of pollution were: South of Al Khor, Al Wakra harbor and South of Doha harbor. Two sampling campaigns were performed, one in summer and one in winter, to evaluate the role of the abiotic parameters, among others, on the bioavailability of the studied contaminants.
The native pearl oyster Pinctada radiata was selected as model and surrogate species due to, its wide distribution along the Qatari coast, filter feeder and sessile mode of life and to its ability as a bivalve to bioaccumulate pollutants. Chemical analyses of the main trace metals and hydrocarbons were performed in water, sediment and P. radiata samples.
The evaluation of the aneuploidy levels in P. radiata was estimated in 25–30 animals from each sampling site and season, by counting the total number of aneuploid metaphases over 30 metaphases counted per individual.
The evaluation of the aneuploidy level on Pinctada radiata from the three sampling sites revealed an occurrence of significantly higher levels in Al-Wakra harbor (17% in summer and 20% in winter) and South of Doha harbor (19% in summer and 17% in winter), when compared to Al Khor (5% in summer cand 7% in winter). No statistically significant differences were observed between seasons in each location.
In order to investigate the discrepancy between sampling sites and seasons with respect to all estimated descriptors and to evaluate the relationship between all the studied parameters, a principal component analysis (PCA) was performed. Aneuploidy levels were highly correlated to mercury and PAHs levels in the bivalve tissue. Moreover, the higher aneuploidy levels registered at Al Wakra harbor (both seasons) and Doha harbor (summer) showed a high correlation with the contaminants levels in P. radiata tissues. South of Al Khor (in both sampling seasons) was highly positively correlated with Cadmium (Cd), although this contamination was not responsible for a significant increase of the aneuploidy levels.
The studied genotoxic contaminants were found to be highly variable among considered locations and between sampling seasons. Indeed, the 6 observations (contaminants levels among three sampling sites at two sampling seasons) differ substantially, no site or sampling season grouping being observed, which suggests an important spatial and temporal variability of the bioaccumulation of pollutants into P. radiata tissues.
The aneuploidy levels, however, were consistently different among sampled locations, but did not differ between the two sampling seasons, suggesting that aneuploidy is the consequence of a local chronic contamination, and not a direct response to the temporal variability of the contaminants in P. radiata tissues.
The results of this study confirm the suitability of the cytogenetic endpoints to discriminate, categorize the studied sites as regards to their level of contamination, underlining the added value of the detection of the genotoxicity levels in the marine environment to environmental health assessment and mitigation research programs. Further studies should be developed, under the specific hydrological and toxicological conditions of the Qatar Marine Zone (QMZ), to better explain the underlining mechanisms of such genotoxicity in the local filter feeders.
The establishment of a Genotoxicological profile of the QMZ would be a valuable contribution to a wider approach on environmental diagnosis or prognosis, contributing to the protection and sustainability of the QMZ natural habitats and resources.
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Why is it Important to Model the Performance and Reliability of Photovoltaics Under Qatar's Climate?
Authors: Nicolas Barth, Ahmed Ennaoui and Saïd AhziPhotovoltaics (PVs) are the solar harvesting devices currently envisioned to anchor the will of increasing Renewable Energy in Qatar. These devices are planned to be deployed within the next few years to achieve the GW scale. Less oil and gas dependence is important on the very long timescale, as per the perspective of the energy security grand challenge of the state of Qatar. Within Qatar Environment and Energy Research Institute (QEERI), HBKU, Qatar Foundation, we are developing modeling and numerical simulation tools that aim at predicting the behavior and performance of photovoltaic panels. Based on scientific grounds, this work also aims to show how such a predictive tool is important for the energy transition of Qatar.
Manufactured PV panels are opto-electronic devices having as a core the solar cells, sandwiched within electrical collectors, generally connected together in modules that are finally encapsulated and mounted as the panel. For silicon-based solar cells, the mainstream technologies feature different laminated materials such as a front glass layer, encapsulating polymers and a metal-based back-sheet. Our initial modeling and related results are based on a two-dimensional design of the PV panel, with interest in the through-thickness physical state inside the panel.
Our current modeling is developed following a multi-physics approach capable of simulating the performance as function of the thermal behavior under any atmospheric conditions – and for any mounting conditions. We particularly consider the harsh conditions of Qatar's hot and humid desert climate. The modeling scheme of this initial work is illustrated in the support Figure that should be attached to this abstract. The computational code consists in three sub-models for this initial multi-physics modeling:
(1) the solar irradiance modeling which places the PV panel under mounting conditions within an environment having direct Sun light, diffuse light irradiance from the sky, and ground-reflected irradiance (albedo);
(2) the thermal modeling, allowing to compute the through-thickness temperature of the PV panel;
and (3) the electrical modeling, assuming a perfect yield of the current–potential “I–V” curves of the PV device (which is to say that the PV module is assumed stationary on the grid at its maximum power point, whatever the irradiance and temperature conditions).
The through-thickness temperature is then obtained within the PV device throughout the undertaken computational experiments. This temperature field is resulting from heat dissipation effects at the boundaries of the PV panel due to convection and radiation in the thermal environment, where ambient temperature and wind speed of the air may vary. Moreover, the solar irradiance data from Qatar is also used as input for the PV device at the front interface of the solar cell in the PV panel. Following this input from the solar radiation, and at any simulated time, the electrical yield of the PV device is also taken into account in the thermal balance. This can be done since the solar radiation not converted into electrical energy should end up as a thermal energy source (the device is not in open-circuit conditions).
Following this approach, we established numerical methods with application to long-term service (>1 year) conditions simulations, relevant to the Gulf region of silicon-based PV modules. Thermal variations are obtained due to the alternation between daylight and nights in Qatar, as well as seasons.
It can be noted that the PV performance simulations are used as first approximations to estimate long-term performances of the PV devices in Qatar. Later, in future works, the models will be coupled to the reliability and failure mechanisms relevant to the warranty period and consensus lifespans of the PV technologies. In future works, it is also relevant to account for soiling effects due to dust in Qatar, and estimate the nominal performance of PV panels/arrays/plants with mitigation solutions (cleaning etc.).
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Modeling and Mapping the Optimum Sites for PV Solar Energy Farms in Qatar Using Geographic Information System (GIS)
Authors: Yasir Elginaid Mohieldeen, Hissa H. Al-Hajri and Diego MartinezThe State of Qatar wants to generate 20% of its electricity requirement from solar power by 2020. This policy aims to meet the increasing electricity demand induced by increasing population and the associated urbanization with its energy-hungry life-style while adopting at the same time environmental-friendly renewable energy. Qatar's population has increased almost five times from 0.37 million to 1.74 million between 1986 and 2010, and six times between 1986 and 2014.
The electricity and water company in Qatar KAHRAMAA has reported an increase in the maximum network load from 941 MW in 1988 to 3,990 MW in 2008 and reached 6255 MW in 2012. The number of customers increased from 132,429 in 1998 to 293,604 in 2013.
This increase in demand is triggered also by changes in life-style, indicated by electricity per capita consumption figures. The per capita consumption grew from 12.963 KW to 17.774 KW in 2007.
To meet this increasing demand for electricity, and as a dry country with no hydro-power resources, Qatar has increased the number of gas-generated electricity plants in the 2000s from 3 to 8 plants. Gas energy is used to generate electricity in these plants.
Qatar is ranked as having the second-highest per capita ecological footprint among 150 countries, down from being the highest in 2012, according to the WWF's Living Planet Report. This report is published every two years. With these environmental concerns and the unstable oil prices in mind Qatar has decided to introduce clean renewable energy to produce electricity as opposed to non-renewable environmentally un-friendly natural gas.
Solar energy is arguably the most effective way to meet the increasing energy demand of Qatar and the region, for the following reasons: firstly, solar energy is renewable as opposed to the non-renewable gas and oil which are finite resources. Secondly, solar energy is clean and limits the emissions of Greenhouse Gases. Thirdly, using solar energy lengthens the life of oil and natural gas resources, and reserves them for future generations.
A preliminary analysis of solar energy potentials carried out by QF-QEERI using historical data collected by Qatar Meteorological Department (QMD), reveals that there is a high potential of solar energy in Qatar. The ground-measured yearly average Global Horizontal Irradiation (GHI) for Qatar is 2113 kWh/m2/year. GHI is suitable for the Photovoltaic (PV) method of converting solar energy into direct current electricity.
The selection of optimum sites for Photovoltaic (PV) solar energy production facilities has been one of the single most sought after objectives by solar scientists, and decision makers, as it can determine the success or the failure of solar projects with big budgets.
In the State of Qatar one of the main issues that faces large scale implementation of solar Photovoltaic (PV) energy production is the availability of land. With an area of 11,500 km2, including growing urban centers, agricultural farms, industrial cities, and with most of the desert areas are environmentally protected land, or used as utility corridors such as oil and gas pipes, or reserved for future plans, finding large tracks of land for solar farms is not an easy task/exercise.
Multi-criteria analysis is carried out in this study using ESRI ArcGis to identify the optimum sites for solar energy farms in the country. Criteria for land suitability for solar farms has been identified and used in the GIS analysis and model building, these are: land slope, aspects, proximity to coast-line, proximity to roads (i.e. accessibility), proximity to electric grid, restricted areas, urban areas, environmentally protected areas, and water ponds. These criteria are then used as a base for assigning suitable weights in the model building in MODEL BUILDER of ArcGis software. Different geospatial analysis techniques were included in the model such as, buffering, surface analysis and weighed overlaying of datasets.
The main result obtained in this study is the model itself, as it can be run with different sets of scenarios according to the requirements of the scientists and decision makers. The model produces maps showing the optimum sites for PV solar energy production in Qatar.
GIS is proved to be very efficient (time and cost effective) tool in finding solutions to such cumbersome problem, where many factors need to be taken into account. The project demonstrates a real application of GIS where it is used as a decision making tool at a national level projects.
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Developing Targets for Power Generation from Multiple Hot Streams
Authors: Omar Al-Ani and Patrick LinkeEnergy efficiency is growing in importance as governments move to decrease their dependence on fossil based fuels. There are many industries with waste heat streams that need to be cooled down to lower temperatures. The excess heat from these hot streams can be used for generating power using a thermodynamic cycle (such as an Organic Rankine Cycle). A natural first step for assessing such power generation options would to determine the thermodynamic limits that exist for maximum power generation from the single or multiple hot streams. Similar to energy targets from the well-established Pinch Analysis techniques, such power generation targets could inform decision making on pursuing power generation options for the how streams. To date, little work has been done on determining a target efficiency for power generation from multiple waste heat streams. This work is the first to propose two rigorous targeting approaches.
The first approach is based on Carnot efficiencies. As the Carnot cycle is the most efficient power generation cycle, the approach will yield a benchmark in terms of the maximum power that can be generated from the waste heat streams under ideal conditions. The targeting approach will be derived and explained for the general case of multiple hot streams. It will be presented for two common cases of information on multiple hot streams, i.e. the availability of individual hot stream data and the availability of aggregate hot stream data in the form of a composite curve. The Carnot power generation targets cannot be exceeded by real power generation cycles and present the thermodynamic limits for the system. The Carnot targets can be developed very quickly using the proposed approach to inform decisions. The Carnot targets inform the design engineer of power generation potential so that further study can be decided upon (or not) swiftly.
The second targeting approach takes into account the characteristics of real power generation cycles in the form of steam or organic Rankine cycles. The Rankine cycle is chosen in this work as it is the most common thermodynamic cycle employed in for power generation from low grade heat. The proposed approach takes into account the properties of working fluids and a minimum temperature difference between power cycle and the multiple available hot streams. Because of considering the real fluids and driving forces in heat transfer, the targets from the second approach are lower than the Carnot targets from the first approach, but are approachable with real power generation cycles. The real system targets inform the design engineer of power generation potential with Rankine cycles so that further study can be decided upon.
We will focus our presentation on communicating each targeting approach as an easy to use, step by step procedure. Both targeting approaches presented in this work will be illustrated using examples involving power generation from multiple hot streams. We will specifically emphasize the importance of taking a systems view across multiple hot streams when developing power generation systems against multiple hot streams. We will conclude with an outlook on Rankine systems design against multiple hot streams to develop concrete cycle configurations with increased complexity towards the real systems targets.
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Mapping and Sequencing of Sex Determination Genes in Phoenix Dactylifera
Date palm (Phoenix dactylifera) is one of the most important crops in many arid land cultures. The date fruits are rich in essential nutrients, minerals, vitamins and fiber, making them a critical food source linked to the history of the Arab world. The most frequent method of propagation is by offshoots, which guarantees that the characteristics and quality of the fruit are maintained; however, it significantly reduces the genetic variability of the date palm plantations, making them extremely vulnerable to pests and diseases. During the past few years, advances on date palm research have provided some information about the molecular markers associated with different desirable agronomical traits, including gender and fruit color.
We recently showed that P. dactylifera employs and XY sex-chromosome system, and generated a genetic map that localized this gender determination locus to the lower arm of linkage group 12. Based on this initial information, we designed markers to screen a Bacterial Artificial Chromosome (BAC) library of a male P. dactylifera to sequence the X and Y alleles in date palm. A combination of approaches that include next-generation (Illumina) and Single Molecule, Real-Time (SMRT) Sequencing (PacBio) of more than one hundred BAC clones, have allowed us to map eighty markers to eleven larger DNA contigs, containing the corresponding female and male specific regions, spanning approximately 4Mb. However, multiple sequence gaps still exist within and between the sequenced region, and further analysis have indicated that the borders of most assembled contigs correspond to repetitive elements, which likely constitute a big portion of the unassembled DNA sequences. Non-recombining regions of sex chromosomes, particularly the Y chromosome, are highly repetitive due to degeneration, making it more challenging to design markers and extend the assembled sequences by chromosome walking.
These observations, led us to propose a parallel approach to complement and advance on the initial sequencing strategy. Date palm, and all other thirteen members of the genus Phoenix, are dioecious, with roughly half of the individuals planted from seed expected to be fruit-bearing female trees. The conservation of dioecy in this entire clade in the Palm family (Arecaceae) suggests that in the genus Phoenix, dioecy evolved before speciation. Therefore, we recently started using comparative genomics to analyze male and female individuals from the remaining thirteen Phoenix species, which has allowed us to narrow down the Y-specific region to a very small portion of the genome, containing only a few genes. Our latest findings are providing a new insight into the evolution of plant sex chromosomes and sex determination in date palm. Standardization and validation of new methodologies that allow for large-scale sequencing and analysis of polymorphisms in date palm, will provide valuable tools for the development of marker-assisted selection programs, for the improvement of date palm production. This will allow Qatar to diversify the varieties of dates it grows, and in the near future will allow us to test for the most desirable agricultural traits, which will significantly improve the quality of the fruit, making Qatar a more competitive date producer in the region.
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New Approach in Adsorption Reactor Design for Refrigeration and Heat Pumps Applications
More LessMost adsorbents used in reactors of adsorption refrigeration and heat pump systems are often initially manufactured for different applications namely drinking water treatment, waste water treatment, gas storage, gas and liquid filtration or separation in industrial processes, dehumidification process. Furthermore there will be a requirement of mapping of refrigerant specific uptake against operating conditions mainly temperatures and pressure: this will require to a large number of experimental data for the pair studied (adsorbent-refrigerant) characterisation. Therefore, the adsorbents found in the market will not necessary offer optimum performance for adsorption refrigeration and heat pumps applications. In order to address this issue and in the prospect of manufacturing specific activated carbon adsorbent, a research work is carried out at Warwick University with the objective of screening a large number adsorbent models (more than 60,000) and identifying suitable ones with optimum characteristics for three applications: Ice marking (TC = 35oC, TE = -5oC), Air conditioning (TC = 35oC, TE = 15oC) and Heat pump (TC = 40oC, TE = 5oC). For each application, the driving temperature will range from 90oC to 250oC. The method consists of using Dubinin-Astakhov modified equation [1] and establishing the maximum refrigerant uptake variation for each application. For this purpose the three key parameters of adsorbent-refrigerant will be varied: xo (maximum uptake of refrigerant by the adsorbent in kg refrigerant per kg of adsorbent) from 0 to 1; K (energetic affinity characteristic of adsorbent-refrigerant pair) from 1 to 50 and n (characteristic of adsorbent micro-pores size distributions) varies from 0 to 6. Overall, the preliminary simulation results show that for each adsorbent model with each application, the refrigerant uptake variation has an optimum (Fig. 1). Furthermore and as expected at high temperature, those optima values are tailed off by the maximum uptake of refrigerant xo (Fig. 2): it is therefore appropriate and practical to consider 90% to 95% of the value for n and K selection. Figure 3 is an illustration of specific cooling capacity for Air conditioning application. Future simulation work will also include evaluation of both heat desorption and heat of adsorption therefore the coefficient of performance (COP). Before any attempting of manufacturing any sample of a given model of activated carbon, further additional work will include simulation performance of a full model of adsorption refrigeration and heat pump systems already available [2, 3].
References
[1] Z. Tamainot-Telto, S.J. Metcalf, R.E. Critoph, Y. Zhong, R.N. Thorpe, “Carbon-Ammonia pairs for adsorption refrigeration applications: ice making, air conditioning and heat pumping”, International Journal of Refrigeration, 32 (6), pp. 1212-1229, ISSN 0140-7007 (2009)
[2] Z. Tamainot-Telto, S.J. Metcalf, R.E. Critoph, Novel compact sorption generators car air conditioning, International Journal of Refrigeration, 32 (4), pp. 727-733, ISSN 0140-7007 (2009)
[3] S.J. Metcalf, R.E. Critoph, Z. Tamainot-Telto - Optimal cycle selection in carbon-ammonia adsorption cycles – International Journal of Refrigeration, 35 (3), pp. 571-580, ISSN: 0140-7007 (2012).
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Multiscale Modelling of Carburization of Steel Through Fe-110 Surface and Role of Vacancy Defects
Carburization of metal is a catalytic reaction that occurs on metal surfaces exposed to hydrocarbon atmosphere at high temperatures. This reaction is a form of the well-known Fischer-Tropsch synthesis and is immensely important to various industrial aspects, most notably metal dusting corrosion (MDC) [1] and catalytic conversions [2]. On Fe surfaces, carburization occurs at high temperature, initiated by adsorption of gaseous hydrocarbons and is responsible for triggering both MDC, a catastrophic failure of the structural integrity of metals and alloys and a severe threat to the petrochemical industries, and a central reaction in catalytic converters, that are purposefully designed to produce a high yield of carburization to reduce the emission of toxic gasses. One of the most abundant and widely-studied carburizing gas is carbon monoxide (CO) that has been observed to react with Fe surface and dissociate at temperatures 600–900 K. In a hydrocarbon environment, the reaction is given by,
CO+H_(2) ( → ⊥ 800K)[C^* + H]_2|O
Where C* is adsorbed on the Fe surface. The reaction is sustainable without the presence of hydrogen [3]. Gaseous hydrogen reacts with O atoms deposited on the surface from the dissociation of CO and removes the O atoms as steam [4].
From atomic to continuum scale, the reaction characteristics have been studied widely using computer simulations of various approaches and have produced reliable results and predictions in agreement with relevant experiment results [5–9].
From an atomistic modelling perspective, the reaction between CO and Fe surface can be broken into two consecutive processes, adsorption and dissociation. Adsorption describes the process of a CO molecule getting attached to the Fe surface. During dissociation, this molecule decomposes into C and O adatoms directly at the surface, with the two atoms moving into their most stable adatom site. Adsorption of CO is a barrier-less exothermic process. Dissociation, on the other hand, is an endothermic process that requires breaking a C-O triple bond, displaying an 11.2 eV/molecule average dissociation energy in vacuum [10]. The catalytic effect of the metal surface plays therefore a crucial role for breaking this bond at a much lower energy [4]. Earlier density functional studies show that on Fe-110 surface, the CO dissociation barrier is close to 1.5 eV [8]. However, this energy is still high in order to achieve from thermal activation only. A number of experiments suggest that the temperature threshold for CO dissociation can be as low as 380 K [11]. Therefore, it can be assumed that in practice, the reaction pathway is more complex than it has been modelled in previous works [7, 8] and one has to take into account that the metal surface contains impurities and defects that could assist the dissociation process [12]. Furthermore, the interactions originating from the periodic boundary condition of the simulations must be evaluated and dealt with accordingly. Commonly, an unwanted interaction from periodic boundary condition can be minimized by choosing a large simulation box. However, large simulations are computationally expensive and therefore an efficient method should be developed that can describe the CO-Fe surface reaction accurately yet is sustainable regarding computational resources.
In this work, these challenges are addressed with a systematic study of the adsorption and dissociation of CO molecule on Fe surface, following further diffusion of C atom to subsurface and bulk using a multiscale technique combining atomistic density functional theory and empirical potential (EP) method. For atomistic scale study, we used density functional theory (DFT) with PBE-GGA pseudopotential technique implemented on the VASP code. Preliminary investigations on different low-index Fe surfaces confirm that the 110 surface is the most densely-packed surface and has the minimum structural reconstruction and minimum surface energy and is chosen as standard for our work. Hence we successfully reproduced CO adsorption energies, energy profiles for dissociation and subsurface diffusion of the C, in good agreement with results computed in earlier works [7, 8, 13, 14]. However, we have noticed that the periodic boundary condition applied to these simulation, which is also used to control the concentration of CO on the surface (coverage), has a significant effect on the energetics of these processes. The CO molecule has a strong dipole moment and it leads to van der Waals interaction between the molecules [15] adsorbed on the surface. Taking van der Waals interaction into consideration, adsorption energy studies on surfaces with CO fractional coverages of 0.25 and 0.0625 monolayers (ML) reveal that adsorption CO on 110 surface is energetically more favourable at dilute coverages. Most importantly we demonstrate here that the dissociation of CO also is energetically favourable in dilute surface as the energy barrier is reduced to half when the CO-coverage is reduced from 0.25 to 0.0625 ML [16].
Since one expects surface defects to be present on Fe surfaces and to act as corrosion initiator, here we show computationally using accurate electronic structure calculations that the single vacancy defects on the surface are energetically inexpensive and therefore prone to be naturally abundant. In fact, we find that vacancy defects lower the adsorption energy for CO molecules adsorbed next to a vacancy and allows the C atoms to diffuse to the subsurface layers through the cavity. As a result, the reaction path becomes more complex and in order to examine the role of defect in the carburization process, one must compare the pathway with the combined pathway of dissociation of CO on clean surface, and subsequent surface to subsurface diffusion of C. It is worth noting that in the previously published works on surface to subsurface diffusion of C, the O adatom, as a by-product of the dissociation reaction, is ignored and its effects not taken into account. We take the O adatom adsorbed on the surface into consideration in this work and we carried out electronic structure and charge density analysis. It is demonstrated here that the influence of the O adatom is quite significant: 1. The O atom does not directly bond with the Fe surface but due to its high electron affinity, electronic charge is transferred from the surface to the O atom via the Fe-C bond in order to facilitate the breaking of C-O bond. 2. A surface vacancy defect creates an electron deficit that restricts the C atom from forming strong covalent bonds with Fe atoms. Interestingly, even after the C-O bond is completely dissociated, the O atom influences the surface-to-subsurface diffusion of C. Calculation of surface-to subsurface diffusion paths with and without O adatom on the surface shows that in presence of O, the diffusion barrier is higher and the C penetration depth into Fe is lowered.
The dissociation and diffusion pathways discussed above were estimated using the nudged elastic band (NEB) method [18]. In order to find a transition state, the end-point (initial and final) configurations for the reaction are first fully relaxed with high precision. NEB uses an interpolated chain of intermediate configurations between the two end point configurations, connected by springs. The whole chain is then relaxed simultaneously with a fixed spring constant until the total average force minimizes under the tolerance limit of 0.01eV/Å. In this work, 8–16 intermediate configurations or images are considered, depending on the length of the path. It is evident that these calculations with DFT are extremely demanding regarding computational resource and therefore we need to anticipate the best possible dissociation/diffusion path with to minimize computation time. This issue is addressed by employing a combined empirical potentials (EP) – DFT technique where we employ the LAMMPS code, to pre-estimate possible minimum energy paths for dissociation and diffusion using NEB and from empirical Molecular dynamics simulations that are able to easily treat thousands of atoms thus increasing the length scales.
Starting with the converged set of configurations from this pre-estimated transition pathways using EP, DFT is used to obtain more precise results. With the use of a potential that has been extensively tested to yield results in agreement with DFT [17], the pre-estimate shortens the computational time significantly. For the calculation of the surface-to-subsurface diffusion path of C, this process has reduced the computation real-time from 33792 to 18464 CPU-hours, which is a 45% drop, still producing identical results within the tolerance of 0.01 eV. However, in order to predict a reliable pre-estimate the potential needs to be tested with DFT. The embedded atom method (EAM) potential used in this work by Becquart et al [18] is rigorously calibrated with several DFT-estimated parameters. Unfortunately, this potential represents only Fe-C systems and for surface calculation with CO, we must consider a potential representing a Fe-C-O system. For this purpose, we have also been characterizing a reactive force-field potential designed by van Duin et al [19], specifically for catalytic reaction on Fe. This potential is anticipated to be used in near future to provide a complete atomistic description of this reaction mechanism. Which efficient multiscale technique are you referring to?
In summary, the computational understanding gained in this study on the role of vacancy defects on dissociation of CO molecule, followed by subsurface diffusion of C, is beneficial for predicting the nature of the CO-Fe reaction for a practical scenario such as presence of larger vacancy defects on the surface and whether they act as dusting corrosion initiators. Simulation at different length and time scale are underway towards modelling physical and chemical phenomena governing the carburization of steel. Acknowledgement: The advanced computing facility of Texas A&M University at Qatar is used for all calculations. This work is supported by the Qatar National Research Fund (QNRF) through the National Priorities Research Program (NPRP 6-863-2-355).
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Electronic and Transport Properties of Transition Metal Dichalcogenidies in the Framework of the Complex Band Structure Analysis
Authors: Dominik Szczesniak, Ahmed Ennaoui and Said AhziIn recent years, novel two-dimensional (2D) materials have attracted much attention due to their unique properties and numerous possible applications [1]. In particular, one of the key domains that can be addressed with the 2D materials refers to the energy conversion and storage [2]. In this context, the novel monolayer group-VI B transition metal dichalcogenides (MX2, where M = Mo, W and X = S, Se, Te) are of special interest. Specifically, the MX2 monolayers are characterized by the high charge mobility [3] and direct electronic band gaps in the visible spectrum range [4], which allows their use in the low-dimensional tunneling transistors [3], [5], photodetectors [6], [7], or solar cells [8], [9].
In such electronic and optoelectronic applications, the electronic transport processes play a pivotal role. In particular, the functionality and efficiency of the low-dimensional systems are highly influenced by the quantum effects that forbid their investigation within the classical regime [10], [11]. From the theoretical point of view, the quantum transport phenomenon is usually described in the framework of the Landauer-Büttiker theory [12], [13], which relates the scattering theory to the quantum electronic conductance. In what follows, the central role in Landauer-Büttiker formalism is played by the transmission probabilities, familiar in the scattering theory, which can be expressed in the terms of the bulk solutions of the Schrodinger equation.
These bulk solutions of the Schrodinger equation incorporate both the propagating and evanescent electronic states that compose the so-called complex band structures (CBSs) of the solids. However, the importance of the CBSs is not only restricted to the quantum transport simulations, where they are used as a complete basis set of the electronic states for calculations. Notably, CBSs allow for capturing the properties of solids that are beyond the typical electronic band structure analysis, e.g. the surface states [14], [15], the localized edge states [16], [17] or decay characteristics of localized states [18], [19].
In the present communication we report the recent calculations of the CBSs of monolayer MX2 materials (where M = Mo, W and X = S, Se, Te) [20]. Herein, the basic electronic properties of MX2 systems are described by using the tight-binding (TB) model [21] which permits the spin-orbit coupling (SOC) effects. The adopted TB model allows describing the most important features of the MX2 systems, presenting at the same time predictive capabilities of more advanced theories. Next, the CBSs of MX2 materials are calculated from the developed nonlinear generalized eigenvalue problem (NGEP) method. The electronic states obtained from the NGEP method are characterized and classified due to their functional behavior in the momentum space. It is shown that the calculated CBSs strongly depend on the SOC interaction and present the band spin splitting of the electronic branches. Moreover, the complex loops, which describe the tunneling currents at the direct band gaps, are observed. Their characterization is given regarding the decay behavior of the corresponding evanescent states that create the complex loops. The discussion is supplemented by the analysis of the importance of CBSs in quantum transport calculations for MX2 monolayers, and by the perspectives for further research in this domain.
References
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Photodegradation of Organic Pollutants Using an Efficient Molybdate Intercalated Mg 2+ /Fe 3+ Layered Double Hydroxide (LDH)
Authors: Syed Javaid Zaidi and Lagnamayee MohapatraOrganic pollutants dyes are the highly toxic major waste products causing severe harmful environmental pollution. From the viewpoint of environmental issues, the removal of harmful organic dye compounds is of great interest and importance1. Traditionally physical and biological methods are generally used to decompose many organic pollutants. However, these methods suffers from certain disadvantages and are time-consuming process. 2,3 Visible-light photocatalysis has been renewable “green” technologies which can harvest solar energy in the environmental remediation capable of removing harmful heavy organic contaminations4. This presentation is focused on the design of a novel kind of photocatalyst that cover entire solar spectrum i.e. from ultraviolet to infrared (IR) regions to decolorize and degrade the organic dye such as rhodamine 6G in an effective way.
Now a days, the use of layered double hydroxides (LDHs) as active photo-catalysts has been receiving considerable attention over the layered metal oxides. A number of photocatalysts have been reported for the photocatalytic degradation of organic pollutants. Among the new generation photocatalyst, LDH was very much promising material for pollutant degradation5. However, designing novel visible light active LDH catalysts to meet present technical requirements is a great challenge. Intercalation of different polyoxometalic anionic species into inorganic layered materials like layered double hydroxide (LDH) offers a technique in which altering the properties of the two components are combined into a single modified material. By intercalating different anions, the characteristics of the layered double hydroxide (LDH) can be improved. Layered double hydroxide basically called Hydrotalcite consist of a cationic brucite like sheets with anionic moieties in the interlayer through electrostatic interaction. The unique structure, surface hydroxyl groups, interlayer spaces with intercalated anions, swelling properties, oxo-bridged linkage and high chemical stability are some of the added advantages of this group of materials. To harvest solar energy efficiently a series of Mg/Fe Layered double hydroxide materials has been synthesized by hydrothermal method and modified by intercalating molybdate anion by ion exchange. These materials have been characterized by various techniques and tested for their photocatalytic activity for the pollutant removal.
The broad absorption band in case of Mg/Fe LDH was found due to the metal ligand charge transfer band of O2p →Fe3+ and the metal-metal-charge-transfer spectra of Mg2+-O-Fe3+. The metal to metal charge transfer (MMCT) for an oxo-bridged bimetallic system with different oxidation states was defined to be an excitation transition of an electron from one metal to the other, which is known to absorb visible light and even near-IR light. 6,7 In the case of Mg/Fe/Mo LDH, the absorption edge shifted towards near IR is due to the HOMO-LUMO OMCT of Interlayer Molybdate where the HOMO is mainly derived from the O 2p orbitals and the LUMO is from the Mo 4d orbitals. These materials show enhanced photoactivity for the degradation of organic dyes such as rhodamine 6G. The enhanced photoactivity is due to edge shared metal oxygen octahedron of (MO6) of brucite sheet, visible light absorbing species, low recombination of charge carriers’, metal-metal charge transfer spectra (MMCT) of the oxo-bridged bimetallic Mg2+-O-Fe3+ system, long life time of photogenerated charge carriers and HOMO–LUMO oxygen metal charge transfer spectra of intercalated Molybdate anions. These modified photo catalysts can be reused easily with several times without substantial loss of catalytic activity, which is green alternative material for practical applications for degradation of organic dyes like rhodamine 6G.
References
1. Yanlan Liu, Kelong Ai, and Lehui Lu, Chem. Rev., 2014, 114, 5057–5115.
2. Ana Ballesteros-Gómez, Soledad Rubio, Anal. Chem., 2011, 83, 4579–4613.
3. Ian L. Gunsolus and Christy L. Haynes, DOI: 10.1021/acs.analchem.5b04221.
4. Y. Takahashi, S. Kubuki, and T. Nishida, Green Catalysts for Energy Transformation and Emission Control, Chapter 4, 2014, 71–84.
5. K. J. Klabunde, Nanoscale Materials in Chemistry: Environmental Applications, Chapter 10, 2010, 179–189.
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Ionic Liquids as Multi-purpose Inhibitors to avoid Natural Gas Hydrates during Gas Processing
Authors: Mohammad Tariq, Majeda Khraisheh and Mert AtilhanThe issue of hydrate formation during gas processing is a challenging problem for the oil and gas industries. Billions of dollars spent annually to get rid of the blockage of pipelines due to hydrate clogging by applying various methodologies [1]. Among them injecting chemical inhibitors is the most widely accepted solution; however, choosing a chemical is a difficult task which depends a lot on the gravity of the situation. Generally methanol, glycols and salts also know as thermodynamic inhibitors (THIs) are used which needs to be added in large quantities (50 wt% or above) making them expensive and non-environmental friendly. Also, because methanol is flammable there is always risk and cost associated to its storage. Currently, a new class of inhibitors (generally polymers and surfactants) known as low dosage hydrate inhibitors (LDHIs) are getting much attention which can be used in much less amount (1–3 wt% or less) making them economically and environmentally feasible [2]. Industries are always looking for chemicals which are economic, environmental friendly and have peculiar set of properties. Currently, ionic liquids (ILs) have attracted the attention due to their potential for fulfilling the industrial demands [3]. In this work, we have shown that how a slight variation in the structure of ammonium ILs result in peculiar behavior towards methane gas hydrates.
Five ionic liquids (ILs) belonging to the same ammonium family but structurally and functionally different were tested for their hydrate inhibition ability using a meso-scale rocking-rig apparatus. The first IL studied was tetra-methylammonium acetate (TMAA) which is very similar to a tetra-alkylammonium salt; well known hydrate inhibitors/promoters. The other four ILs belong to choline, also known as, substituted alkyl-ammonium family where one of the alkyl substitutions of TMA is replaced by hydroxy-ethyl functionality. The four choline ILs were attached to anions which are different in nature viz., butyrate and iso-butyrate are isomeric counterparts; whereas hexanoate and octanoate has a difference in the chain length. It has been shown in this work that any slight structural variation in the compound used for hydrate inhibition resulted in a unique behavior. The working concentration and pressure range are also some important factors. It has been shown that at 1 wt% and at higher pressures the Ch-Oct, Ch-But and TMAA act as hydrate promoters. Whereas, at 5 wt% in the whole experimental pressure range (40–120 bar) all the studied ILs act similarly as hydrate inhibitors with TMAA showing the best performance almost comparable to methanol at high pressure. Hydrate suppression temperatures were determined and the performance of individual IL has been discussed quantitatively. Molar hydrate dissociation enthalpies were calculated and their values were interpreted in the light of the thermodynamic inhibition results which indicate that the ILs do not participate in the hydrate cages. Induction time analysis shows that Ch-Oct due to its micelles forming ability acts as a strong kinetic inhibitor which delays the hydrate formation time by more than an hour. Thus, it must be emphasized that a slight structural variations in the structure of ILs reveals their doubly dual nature for methane hydrates system viz., thermodynamic inhibition, hydrate promoter, kinetic inhibition and surfactant character. Since, the used ILs are also biocompatible, non-toxic and biodegradable it make them an excellent alternative class of inhibitors compared to their conventional counterparts.
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The Effect of the Novel FeNiCoAlTa Shape Memory Alloy Treatments on its Corrosion Behavior When Used as a Pipe Coupler
Authors: Hanan Farhat, Ike Oguocha, Richard Evitts and Richard GriffinPipelines are used to transport natural gas and oil. The common way to join the pipes together is welding. Welded areas and heat affected zones have proven to be the weakest part of the pipeline, these areas are often exposed to the environment and as a consequence exhibit more cracks and failures than the rest of the pipe. Such failures lead to leaks of gases, oil, and process fluids that are harmful to the environment. In addition, leaks cause a production loss which is very costly. In the past decades, there have been various leaks that lead to fatalities and that resulted in major environmental impacts.
Shape memory alloys (SMAs), also known as smart alloys, are engineering materials that gained their name due to their unique capability of remembering the shape they had before deformation and returning to it. They undergo reversible solid-to-solid phase transformation (martensitic transformation) when a load, temperature or magnetic field is applied to them, and can recover their original shape if the external stimulus is removed. The most commercially available SMAs are nickel–titanium (Ni-Ti or Nitinol) alloys, which are used mostly in orthodontic and medical applications. These alloys are expensive, have limited temperature range of application, and are difficult to process for large scale applications. Due to these limitations, the current research interest has shifted towards developing new SMAs that are cheaper, exhibit a similar shape memory effect, and that are corrosion resistance.
Among the new SMAs competing with Ni-Ti smart alloys are iron-based SMAs (Fe-based SMAs). Since the discovery of the shape memory effect in Fe-30Mn-1Si in early 1980s, the Fe-based SMAs alloys have attracted the researcher's attention due to their low cost, good mechanical properties, high temperature range of application, workability and weldability. However, they exhibited relatively poor shape recovery which made it necessary to treat them using cycles of thermomechanical treatment known as ‘training’ to enhance their shape memory effect.
The Fe-based SMAs have shown a promising potential to be used as pipe couplers in oil and gas applications. Pipe couplers made from SMAs can be installed easily, and can be a good replacement for welding in pipes. Welding involves heat that affects the structure of the piping metal and the resulted heat affected zone usually possess a favorable location for failure and cracking. This has made Fe- based SMAs pipe couplers a better option due to their low cost and long-term reliability. The use of these alloys to join pipes is aimed to replace the welding process. The SMAs pipe couplers use the shape memory effect to apply a contact pressure onto the surface of the pipes to be coupled. Compared to currently available couplers that work by brazing, smart alloy couplers are easier to install, require lower installation temperatures, and have similar coupling capabilities. The seal is more temperature resistant than that provided by brazed couplers.
In this research, the corrosion resistance of the Novel FeNiCoAlTa (Fe-28%Ni-17%Co-11.5%Al-2.5%Ta) SMA that was developed by the National Aeronautics and Space Administration (NASA) was investigated for using as a pipe coupler. The effect of two different cycles of treatment on the alloy was investigated. In addition, the alloy's corrosion resistance was compared to the resistance of the most common SMA (Ni-Ti or Nitinol). The corrosion potential, polarization resistance and potentiodynamic polarization of the alloys were compared at different temperatures and different PHs. Moreover, the corrosion resistance of the alloy was compared to the resistance of different carbon steel, and stainless steels that are commonly used in oil and gas applications, when electrochemically tested in 3% NaCL solution. The research also investigated the galvanic corrosion of FeNiCoAlTa SMA when coupled to carbon steel and different types of stainless steels. It was found that even though increasing the treatment cycles improved the shape memory effect of the alloy, it reduced its corrosion resistance. One has to decide on whither to enhance the shape memory effect of a pipe coupler or to improve its corrosion resistance. Nevertheless, the alloy exhibited good corrosion resistance, even after increasing the cycles of the treatment showing that it could be a potential replacement to pipe welding.
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Machine Learning Techniques for Defect Depth Estimation in Oil and Gas Pipelines
Authors: Abduljalil Mohamed, Mohamed Salah Hamdi, Sofiene Tahar and Osman HasanCrude oil and natural gas are usually transmitted in metallic pipelines. These pipelines, in some cases extending for hundreds of kilometers, are inevitably exposed to harsh environment such as extreme temperature, internal pressure, corrosive chemicals, etc. Thus, at some point in their lifetime, metallic pipelines are highly expected to develop serious metal-loss defects such as corrosions, which, if left undetected and improperly managed, can cause catastrophic consequences in terms of both damaging the environment and loss of human life, not to mention millions of dollars as maintenance cost to be paid by the owning companies. To avoid such undesirable impacts, the oil and gas industry has recommended that pipeline monitoring and maintenance systems follow a standard safety procedure. The industry standard identifies three types of metal-loss defects, namely sever, moderate, and superficial, based on estimated dimensions of the defect. According to the standard procedure, a defect's depth plays a major role in determining its severity level.
To detect a metal-loss defect and estimate its depth, autonomous devices, equipped with strong magnets and arrays of magnetic sensors, are used on a regular and constant basis to scan the walls of the targeted pipelines, utilizing a well-established technology known as magnetic flux leakage (MFL). The principal concept behind the MFL technology is that when magnetized with two magnets of opposite polarities, a pipeline wall constitutes a magnetic field, in which lines of magnetic force flow through the wall (from the south pole to the north pole). In the presence of a defect, such as a crack, two new poles appear at the edges of the crack. The air gap between the new edges causes the magnetic lines of force to bulge out. The defect depths can be accurately estimated from the amplitudes of the observed MFL signals. However, due to the huge amount of obtained MFL data, manual and visual inspection of such data has proven to be time-consuming, tedious, inefficient, and error prone. Moreover, the cause-and-effect relationship between pipe defects and the shapes of MFL signals is not well-understood, meaning that traditional mathematical models are not available. Therefore, machine learning techniques seem very suitable for managing big data for ill-posed problems such as pipeline defects. Machine learning is a generic term for the “artificial” creation of knowledge from experience. An artificial system learns from examples and is able, after completion of the learning phase, to generalize, i.e., the system does not just memorize the examples, but it “detects” regularities in the learning data. In this, way the system can also evaluate unknown data. Machine learning techniques are applied in a wide range of fields such as automated diagnostic methods, detection of credit card fraud, stock market analysis, classification of nucleotide sequences, voice and text recognition, autonomous systems, etc.
In this work, we propose a machine learning-based approach for defect depth estimation in oil and gas pipelines. To reduce data dimensionality, representative and discriminant features were first extracted from the MFL signals; this in turn, resulted in speeding up the learning process and increasing the new approach performance in terms of estimation accuracy. Statistical methods, as well as polynomial series, were used to extract such meaningful features from 1353 data samples, and in total, 33 features were obtained. The data were organized as follows: 70% for training, 15% for testing, and 15% for validation. The features were fed into a Generalized Regression Neural Network (GRNN), a Radial Basis Neural Network (RBNN), and a decision tree. With the exception of the decision tree technique, both neural network-based techniques achieved a superior performance in terms of defect depth estimation accuracy compared to those obtained by service providers such as GE and ROSEN. For the GRNN, the estimation accuracies obtained are 87%, 81%, and 83% for the training, testing, and validation data, respectively (see Fig. 1 (a)). For the RBNN, the estimation accuracies obtained are 89%, 84%, and 85% for the training, testing, and validation data, respectively (see Fig. 1 (b)). The estimation accuracy obtained by GE is 80% within ± 10 of error-tolerance, and the estimation accuracy obtained by ROSEN is 80% within ± 15 of error-tolerance. The decision tree yielded the worst performance with estimation accuracy at 75% within ± 10 of error-tolerance.
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Determining the Threshold Temperature for Chloride Stress Corrosion Cracking Using a Laboratory Simulation of Field Conditions in Qatar
Authors: Hanan Farhat, John Agcaoili, Jim Fox and Daniel MercierVery few oil & gas installation locations around the world experience sustained high humidity and high temperature for long periods of the year as what is experienced in Qatar. For example, the humidity in Qatar readily reaches 90% and the summer temperature, measured on metal surfaces, can reach 80 °C. The severe temperature fluctuations causes seawater to evaporate, then condense, and then dry on hot metal surfaces, thereby enhancing local build-up of aggressive species such as chloride on the metal surfaces. In some situations, this is complicated by sand storms which leave contaminating sand particles on exposed surfaces in this environment.
Qatar has many oil and gas (upstream), petrochemical and chemical plants (downstream) in both offshore and onshore marine locations. For chloride stress corrosion cracking to take place, three important ingredients have to exist: (i) a critical environment, (ii) a susceptible material and (iii) tensile stress. All these three ingredients exist in Qatar onshore and offshore sites. The presence of residual tensile stresses due to welding or other forming process or fit up stresses from assembly increases the susceptibility of the component to CSCC. Chloride stress corrosion cracking can occur fast when evaporation exists even at room temperature. A number of catastrophic CSCC failures of stainless steels roof construction in swimming pool environments has resulted in human causalities over the past decades. Due to the nature of the local environment and the abundance of stainless steel used in Qatari installations the investigation of chloride stress corrosion cracking (CSCC) of stainless steel alloys is very much warranted.
The critical temperature for application of protective coating to prevent CSCC is still to be identified with any certainty. According to NORSOK standard M-001 recommendations, the maximum operating temperature for 316 stainless steel is 60 °C, and for duplex stainless steels is 100 °C, above which, protective coating has to be applied to prevent CSCC. These temperature limits are being questioned and there are concerns being raised about their accuracy when field evidence shows that cracking is occurring at temperatures below these limits. CSCC can lead to oil and gas leaks that have a major impact on the environment and on public safety as well as production loss.
In this research, a modified ISO drop evaporation test was developed to identify the threshold temperature for cracking for three different austenitic stainless steels, mainly 316, 304 and 904L stainless steels. The samples are prone to load and heat, while Qatar specific seawater is dripped on them, the samples are heated using electrical resistant heating. The test is conducted at four different temperatures (room temperature, 40 °C, 50 °C and 60 °C) and under three different loads (70% σ = < /AσΣETHιγηλιγητ>0.2, 80% σ = < /AσΣETHιγηλιγητ>0.2 and 90% σ = < /AσΣETHιγηλιγητ>0.2). The temperature and load are continuously monitored and adjusted when deviated. The lab-built test setup enabled the testing of sixteen parallel fixtures concurrently. The threshold temperature for cracking for the tested material was recorded at each applied load. Severe pitting was observed underneath the salt layer, and was dependent on the applied load. A new threshold temperature for cracking was recorded and a recommendation to the local industry to revise the threshold temperature for chloride stress corrosion cracking is to be issued.
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Recycling Roads by Rejuvenating Oxidized Asphalt Binder for Sustainable Transport Infrastructures
Authors: Filippo Giustozzi and Maurizio CrispinoThe use of Reclaimed Asphalt Pavement (RAP) material is widespread although the overall amount in the mix and the plant technology vary for each country. Reusing RAP allows for potential benefits due to less material consumption and possible energy savings although the benefit greatly varies depending upon the technology adopted for recycling (hot, warm, or cold asphalt recycled mixes) and material performance during the service life. Performance of recycled asphalt, among several other factors, is strongly related to the binder characteristics which presents himself in a oxidized state due to weathering effects (UV radiation, humidity) and load-related distresses accumulated over the service life.
The present research investigates the use of bio-rejuvenators to recover 100% cold RAP mix and evaluates its possible recycle as a construction material for new transport infrastructures. In particular, the rejuvenated asphalt binder was analyzed through several laboratory experimentations including: standard physical tests, rheology tests in the in-service temperature domain, fatigue resistance, and rutting potential as well as chemical characterization through infrared spectroscopy (FTIR). A multi-approach assessment was indeed found to be essential to comprehensively evaluate the “new” performance of the recycled binder. The Pressure Aging Vessel (PAV) was also adopted to simulate the in-service aging of the rejuvenated binder according to the standards and the multi-approach testing was again adopted to analyze the properties of rejuvenated binder after aging. This allowed characterizing the potential and durability of the “second-life” asphalt.
Asphalt binder was extracted from RAP material following the standard centrifuge extraction and solvent recovery procedure. Preliminary analyses were conducted on the extracted oxidized binder (control binder) and the following was shown, as expected: very low penetration (5.4 dmm); very high softening point (72 °C) and dynamic viscosity; great stiffness and low phase angle value at high temperature (Dynamic Shear Rheometer - DSR analysis); brittle behavior at low temperature (Bending Beam Rheometer – BBR analysis); poor fatigue resistance (linear amplitude DSR test) regardless of the testing temperature but good resistance to rutting (multiple stress creep recovery DSR test) at high and very high temperatures; solid gel structure (microscope imaging analysis) and consequently reduced maltene phase (FTIR analysis).
Several quantities of rejuvenator were cold added to 100% RAP mix and the same binder extraction process was performed. Besides the common quantity of rejuvenator-final performance approach, the rejuvenated binder was also evaluated by taking into account the contact time, which represented the time since the rejuvenator was applied to the oxidized binder, and the relative humidity of the RAP before mixing. It was found indeed that rejuvenators commonly have a differential effect depending on the “curing” time, therefore changing the physical, rheological and chemical properties of rejuvenated binder over time. Relative humidity of RAP material, essential on a plant scale where RAP is commonly open-air stored, was proved to affect with lower magnitude the properties of rejuvenated binder.
The amount of rejuvenator greatly affected the final binder performance; in particular, a greater content helps in improving physical and rheological characteristics in the low-temperature domain. Fatigue damage of the binder was increased (compared to oxidized RAP binder without rejuvenator) regardless of the rejuvenator content but resistance to rutting was reduced. However, the correct proportion of rejuvenator amount depending on RAP humidity and contact time allowed for an acceptable balance of performance in the overall temperature domain. Infrared spectroscopy analysis showed the evolution of carbonyl, sulfoxide and other bands in the rejuvenated asphalt binder.
The adoption of rejuvenators can be considered as an optimal way to improve the recycling of RAP and therefore increasing the amount of recycled material to be included into asphalt mixes without lowering performance and durability; this will allow for substantial environmental savings leading the way towards sustainable transport infrastructures. However, rejuvenators should be always carefully calibrated depending upon the in-service climate conditions of the recycled pavement as well as the initial RAP condition to provide the maximum benefit.
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LLDPE/Graphene Nano-composites: Synthesis and Characterization
The development of nano-composite materials is making a significant impact on modern technology due to their wide range of applications and their superior properties1. Several methods have been proposed and developed to prepare polymer nano-composites. Graphene nano-composites, in particular, have attracted the interest of researchers because of their excellent properties, such as high electrical conductivity, high thermal stability and excellent mechanical strength 2–3. Graphene, a two-dimensional carbon atoms structure, exhibits exceptional properties4–5. Incorporating these nano-fillers with high performance polymers results in a unique combinations of properties.
This paper reports on the synthesis and characterization of graphene and LLDPE (Linear Low Density Polyethylene)/graphene nano-composites with different weight ratios of graphene. Graphene was synthesized from graphene oxide, which was prepared by using modified hammers method. The obtained few layers of graphene were confirmed by different characterization methods such as FTIR, XRD, Raman spectroscopy and SEM. LLDPE/Graphene composites at different weight ratios of graphene, i.e. 1, 4, and 8 wt% were compounded in twin screw extruder. Extruded granules of LLDPE/Graphene materials were used in the preparation of nano-composites by compression molding. In this research, we used the LLDPE as the polymer matrix, because PE (polyethylene) is one of the most common plastic resins in the world and it is produced on a large scale in the State of Qatar by Qatar Petrochemical Company (QAPCO). LLDPE has grown most rapidly within the PE family due to its good balance of mechanical properties and process-ability compared to other types of PE. The effect of graphene ratio on the mechanical, thermal and electrical properties were investigated. LLDPE/Graphene composites with 4% graphene showed higher tensile strength and tensile modulus than the other graphene loading composites. Agglomeration was a problem in the composites with high wt% of the graphene which caused the reduction in tensile properties. Graphene marginally increased the melting temperature of the nano-composites whereas crystallization temperature, thermal stability and electrical conductivity were increased with increase of graphene loading. The results obtained showed that the graphene can increase the thermal stability of the polymer mixture. Increment of thermal stability is due to the high thermal stability of the graphene and the formation of phonon and charge carrier networks in the matrix. The electrical conductivity of LLDPE is 4.28 × 10− 11 and for nano composites is 9.2 × 10− 05. The high electrical conductivity of the graphene converts the LLDPE polymer insulator to an electrical conductor. Electrically conductive PE based composite materials can be used as electron magnetic-reflective materials, as well as in high voltage cables. The enhancement in mechanical, thermal and electrical properties of LLDPE/Graphene nano-composites achieved by melt mixing of graphene into the polymer can enable mass production of new and low cost novel materials with superior tensile strength, thermal stability and electrical conductivity.
References
1. Gossard Didier, Karkri Mustapha, Mariam A. AlMaadeed, Igor Krupa A new experimental device and inverse method to characterize thermal properties of composite phase change materials. Compos. Struct. 2015,133(1), 1149–1159.
2. X. Huang, Z. Yin, S. Wu, X. Qi, Q. He, Q. Zhang, Q. Yan, F. Boey, H. Zhang. Graphene based materials: synthesis, characterization, properties and application. Smal. 2011, 18, 1876–1902.
3. J.R. Potts, D.R. Dreyer, C.W. Bielawski, R.S. Ruoff. Graphene based polymer nanocomposites. Polymer 2011, 52, 5–25.
4. T. Kulia, S. Bhadra, D. Yao, N.H. Kim, S. Bose, J.H. Lee. Recent advances in graphene based polymer composites. Prog. Polym. Sci. 2010, 35, 1350–1375.
5. Du J, Cheng HM. The Fabrication, Properties and Uses of Graphene/Polymer Composites. Macromolecular Chemistry and Physics 2012;213:1060–1077.
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Effect of High Resolution Winds on Wind-Wave Simulations in Arabian Gulf
Authors: Sashikant Nayak, B.S Sandeepan and Vijay PanchangReliable knowledge of wave climate in a large water body such as in the Arabian Gulf for navigation, recreational, maintenance and installation of offshore-infrastructure (e.g. oil platforms) etc. is an important pre-requisite.
Predicting waves in a region like Arabian Gulf, which is approximately 1000 km in length (north to south) and 550 km in width and shallower (average water depth is ∼35 m) requires a well-developed wave model that can account for the shallow water wave mechanisms like their generation, propagation and dissipation. Wave models like SWAN (Simulating WAves Nearshore), WAM (WAve Model) and WAVEWATCH are now routinely run in several parts of the world for predicting and forecasting the ocean waves. Among these, SWAN wave model has been found to be a better model for the shallower and coastal environments.
The quality of wave hind-casts/forecasts made, largely depends on the quality of wind fields (speed and direction) that are feed into these models. For hind-cast, these wind fields can be obtained from observational measurements or reanalysis data from centers such as ECMWF (European Center for Medium Range Weather Forecast), NCEP (National Center for Environmental Prediction). For forecast, the wind fields are obtained from global weather forecast models that are routinely run in centers like ECMWF, NCEP or running weather forecasting models such as WRF (Weather Research Forecasting models) regionally. Further the resolution of wind fields both temporally and spatially affects the quality of wave prediction. For Arabian Gulf, the spatial and temporal resolution of wind fields requires finer resolution than the available reanalysis/forecasts data from NCEP (∼0.5°) or ECMWF ERA-interim (∼ 0.72°).
This study reports on the setting up of SWAN wave model and the improvement in wave modeling by using two sources of surface winds viz. from ECMWF ERA-Interim daily and from a meso-scale high resolution atmospheric model, WRF. Two types of bathymetry are also taken into consideration for running the SWAN wave model. One using a regular bathymetry grid (∼1’, ETOPO1 from NGDC) and the other one using an unstructured mesh bathymetry (for the same ETOPO 1). The advantage of unstructured grid over the regular grid is that it accounts much better for the complex coastal boundaries and islands in the region of interest. Initially, the simulation is carried out for the month of October, 2015. The presence of mesoscale locally convective phenomena's such as land-sea breeze are dominant in a water body like Arabian Gulf. Era Interim reanalysis datasets considered to be the best available wind sources misses these features (because of low resolution) and in turn when used as forcing to the wave models, may result in predicting less accurate wave fields, mostly the directions which in turn effect the non-linear interaction of waves and distribution of energy. The high resolution, mesoscale atmospheric model WRF modeled winds clearly reflects these mesoscale phenomena's and upon forcing to wave model reflects a more accurate wave fields. It is also found that the waves coming from Arabian Sea doesn't impact much in the evolution of waves in Arabian Gulf. The reason may be, their dissipation of energy traveling through the narrowness of Strait of Hormuz. The results are compared with the available buoy data from Qatar Meteorological Department (web portal). Simulated significant wave height (SWH) are also compared with the Satellite SWH's for the same period.
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A Numerical Weather Forecasting System for Qatar
Authors: BS Sandeepan, Sashikant Nayak and Vijay PanchangUnderstanding the features of weather system around and over the Arabian Gulf is a prerequisite for setting up of a numerical weather forecasting system. The reanalysis, ERA-Interim data with a spatial resolution of ∼80 km has been utilized for analyzing the wind climatology for a period of 35 year. It is found that in the Arabian Gulf, throughout the year, the predominant wind is from north-west and the average wind speed is high in the summer between June and August. The high wind speed systems in summer are known as summer Shamals and have a typical duration of one week. Often, the high speed and long duration of the Summer Shamals makes it a good carrier of sand/dust. The winter season is dominated by south-east passage of frontal systems. The presence of land-sea contrast can cause mesoscale wind systems such as land-sea breeze. Qatar being a narrow peninsular region with width less than 100 km, the setting up of these land-sea breeze systems can be from either of the sides. This can lead to the interaction of two sea breezes from opposite sides, which may lead to the development of a convergence zone. This complex systems can affect the local weather and air-quality of coastal areas. These mesoscale phenomena and complexities are not well represented through a global model. Though the low resolution (80 km) data (ERA-interim) shows the presence of Shamal winds, the data misses the detail structure and their spatial variability. This necessitates for setting up of a high resolution mesoscale simulation approach.
A non-hydrostatic mesoscale model, Weather Research and Forecast (WRF) developed by NCAR (Skamarok et al 2008) is used here for simulating and forecasting the wind systems associated with the Arabian Gulf. The model is run on an operational basis to forecast the wind fields, for a 48 hr. The modeling suite consists of a preprocessor, WPS, the model, WRF and a post processor, ARWpsot. The total suite has been compiled and installed successfully using FORTRAN and C compilers. A two way nested WRF domains with a grid size ratio of 1:3 is configured. The resolutions for the outer domain and inner domain are set to 9 km, and 3 km respectively. Various physical parametrization schemes are available within WRF modelling system. The physical parameterization schemes used in the current configuration includes MYJ boundary layer parametrization, Janjic Eta Monin–Obukhov surface layer scheme, Dudhia shortwave radiation, Rapid Radiative Transfer Model (RRTM) long wave radiation, WRF Single-Moment 6-Class (WSM6) microphysics, and the NOAH land surface scheme. Cumulus scheme, Grell is used only for the outer domain. Both of the model domains have a total of 39 vertical levels, with the topmost level at 50 hPa and lowermost level at approximately 30 m above the ground level. The initial and boundary conditions are obtained from the National Centers for Environmental Prediction's (NCEP) Global forecast System (GFS) available at resolution 0.50 (∼50 km), and the boundary conditions are updated at 6 hr interval. The entire process is automatized and run on RAAD Linux HPC cluster computing system.
A two day simulation of WRF is analyzed and the sea breeze system of Qatar peninsula is examined and compared with the automatic weather station (AWS) data of Qatar Meteorological Department. The time of onset and duration of sea breeze are identified. The simulation of WRF clearly shows the development of a thermal internal boundary layer over the coastal city Doha. The existence of a convergence zone with high vertical updraft was also found. This may be due to the interaction of sea breezes coming from opposite sides of Qatar peninsula. Understanding the system of sea breeze would benefit the overall understanding pollutant transport and the dispersion mechanisms.
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Flexible Integration of EVs and PVs into the Electricity Grid
Authors: Mladen Kezunovic and Haitham Abu-RubWith the unexpectedly fluctuating price of oil and the increasing threat of global climate change, Electric Vehicles (EVs) and renewable energy, particularly photovoltaic (PV) generation are becoming a viable option since they are not directly affected by the unstable oil price and yet are environmentally friendly.
The PV generation has attracted attention in the “Solar Belt” countries, especially in Qatar where annual mean of global solar radiation (around 2000 kWh/m2/year) is large. The ample roof space on large residential and commercial buildings in Qatar and ability of the PV panel covers to protect vehicles from the exposure to sunshine makes the use of PV generation a natural choice.
When connected to the grid, EV battery can behave as mobile energy storage making EV capable of either charging via grid-to-vehicle (G2V) as a “load” or discharging via vehicle-to-grid (V2G) or vehicle-to-building (V2B) as a “generator” or a dispatchable “back-up storage”. This bi-directional power flow feature provides flexibility needed to match variability of the renewable sources. The integration of electric vehicles and PV generation achieves two goals: a) it displaces the urban tailpipe pollution to the location where the power plants are, which typically in rural areas, and b) it allows energy storage when solar generation is active, which is mostly during the day, and discharging during the night, which allows better control of the generation variability.
The objective of this paper is to discuss the methodology and technology needed to coordinate EVs' charging and PV-based generation in order to improve the performance of electric grid and at the same time reduce the environmental pollution. The paper focuses on three issues: a) integration of photovoltaic (PV) generation and EV charging stations through DC or AC bus, b) interfacing the DC or AC bus to the power system using advanced power electronics, and c) analysis of the impacts of the PVs and EVs on the power grid operation. The integration and interfacing will be optimized to support several utility applications: demand side management, outage management and asset management.
The different modes of interfacing and integrating EVs and PVs into the grid are defined under different scenarios. As an example, the demand side management analysis scenarios under different power grid conditions are shown in Figs. 1 and 2. When power grid demand is low, and the valley filling is needed, EVs can be put into charging via G2V mode and combined with PV generation to keep the power balance between supply and demand, as shown in Fig. 1. When power grid suffers from the peak load and load shaving is needed, EVs can be turned to V2G mode, and combined with PV generation can be utilized to help relieve the demand burden, as shown in Fig. 2. A local battery storage may be used to store the extra power generated from PV or abundant energy from the EV battery to act as the grid interface. The potential impact of EV charging/discharging on the power grid demand profile is simulated. How the grid performance will be improved when PV generation is taken into consideration is investigated. With the interfacing of EV energy storage and PV generation, more energy will be available for flexible control to help grid flatten the demand curve and reduce the peak load. Based on the comparison and analysis, the integration and interfacing of EVs and PVs are coordinated to support the demand side management application.
Proper power electronic solutions allowing bidirectional power flow with fast charging/discharging is also presented. The approach is toward finding optimal solutions in terms of decreasing the time of charging/discharging and adhering to the international standards related to grid side power quality issues. Many high-frequency AC link inverters have been proposed to realize such interface system in the past. One topology is considered promising. It has a bi-directional power flow feature. The inverter operates by first charging the link from the input and then discharging the stored energy to the output. The link inductor (L) stores the energy and the small capacitor (C) placed in parallel with (L) provides the soft switching. Between each power transfer mode there is a resonant mode at which the link inductor and capacitor resonate and no power is transferred. Despite its merits of having a small inductance size, and flexible multiport feature, this converter has two main drawbacks: a) High filtering needs especially at the input terminals, and b) Poor voltage boosting capabilities. These drawbacks are overcome in our proposed novel configuration shown in Fig. 3. Quasi-Z-Source Inverters (qZSIs) have many attractive advantages that are suitable for applying in PV systems and batteries. The use of qZSIs for this configuration has the following good features:
- Higher boosting capabilities.
- Lower harmonic content in input current.
- No filtering requirements at the input terminals.
- Features lower component (capacitor) rating.
On the other hand, a one more power switch (S0) is added to allow bidirectional flow-in case of battery discharging.
According to the battery state of charge, the PV available output power, and the grid availability, the following power flow schemes are possible:
I. When PV is online:
- 1. From PV to Grid, while Battery is offline.
- 2. From PV to (Grid + Battery).
- 3. From (PV + Grid) to Battery.
- 4. From (PV + Battery) to Grid.
II. When PV is offline:
- 5. From Grid to Battery.
- 6. From Battery to Grid.
In case of outage of the power grid, the schemes will be directed to be as follows:
I. When PV is online:
- 7. From PV to local loads, while Battery is offline.
- 8. From PV to (local loads+ Battery).
- 9. From (PV + Battery) to local loads.
II. When PV is offline:
- 10. From Battery to local loads.
The analysis of the impact of EVs and PVs on outage management includes establishing the simulation model of the typical outage condition profile, simulating the performance of PV generation to cover the interrupted load and establishing coordination methodology to make the best use of the energy from PVs and EVs. The analysis of the impact on asset management includes establishing the simulation model of the typical asset management process for existing utility assets, simulating the impact of bidirectional flow due to PV generation, and mitigation of negative asset effects such as overloading due to EV charging and establishing coordination algorithm for minimizing the overall impact of the integration of PV and EV. Evaluation of how transformer maintenance can be optimized under the new operating modes will be discussed.
The results of the study will not only benefit the placement planning for EV charging stations and roof top PV installations to better utilize the electric grid resources, but will also benefit the power grid operation especially the distribution system creating positive environmental impacts paving the road for future large-scale integration of the smart grid flexible load technology in Qatar.
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Microbial Mats from the Khor Al-Adaid Sabkha, Qatar: Morphotypes and Association with Authigenic Minerals
The sabkhas (i.e., salt flats) of Qatar are among the rare places on Earth where carbonate and sulfate minerals similar to those constituting economically important hydrocarbon reservoirs are still forming today, under the arid conditions that characterize the coastline of the country. Since the 1960’s, the sabkhas of Qatar have been studied with great interest as a modern analogue for ancient sedimentary sequences (e.g., Wells, 1962; Illing & Taylor, 1995; Alsharhan & Kendall, 2003). The results of these studies provided important insights for formulating stratigraphic models of subsurface hydrocarbon reservoirs. Notable examples of gas and oil reservoirs that formed in arid, evaporitic environments include the Permo-Triassic Khuff (which is estimated to contain about 15–20% of the world's gas reserves and is of fundamental importance for the economy of Qatar), the Jurassic Arab formations, and the Triassic Kurra Chine, all of the Middle East, and the Permian Zechstein of Northern Europe. Although extremely valuable, most of these early studies were based on purely physical and chemical approaches, which may have not fully captured the complexity of the mineralization processes occurring in the sabkha environment. Indeed, research conducted in more recent years has shown that microorganisms play an important and, as yet, poorly understood role for the mineralization processes occurring in these evaporitic environments (Bontognali et al., 2010; Bontognali et al., 2012; Bontognali et al., 2014; Brauchli et al., 2015; Paulo & Dittrich, 2013; Strohmenger et al., 2011).
Here we present the results of a field campaign conducted in the Khor Al-Adaid sabkha, which is located in the southeast of Qatar, in a large tidal embayment composed of two shallow inland lagoons. The main goal of the field campaign was to identify regions of the intertidal zone that are particularly rich in microbial mats, and that represent ideal sites at which to study microbe-mineral interactions. Three sites of interest have been defined.
Site 1 is characterized by the presence of microbial mats that develop in a restricted pond where abundant precipitation of gypsum takes place. This site is an ideal place to look for geochemical or mineralogical signatures of microbes in the gypsum crystals. This, in turn, may allow for the definition of new proxies for identification of microbially-mediated gypsum in ancient sedimentary sequences. Because gypsum and anhydrite are common seals of hydrocarbon reservoirs, a broad understanding of the mechanism of their formation is of unquestioned interest in the field of hydrocarbon exploration.
Site 2 is characterized by the presence of thick (more than 5 cm) microbial mats. Spherical authigenic carbonate minerals are visibly forming in association with the extracellular polymeric substances constituting these mats. X-ray diffraction analyses revealed that dolomite is among the carbonate minerals forming at this site. Thus, the mats will be studied with the goal of providing new insights helpful in solving the long-standing enigma surrounding the origin of sedimentary dolomite. Dolomite is a common mineral in ancient sedimentary sequences (including many hydrocarbon reservoirs) but historically it has been very difficult to form in laboratory experiments that simulate Earth's surface conditions. For this reason, the mechanism of its formation remains highly debated. It has been proposed that microorganisms play a key role for overcoming the kinetic barriers that prevent dolomite formation at low temperature (Vasconcelos et al., 1995). Because this “microbial hypothesis” is not unanimously accepted, the mats present at site 2 represent an ideal material to study for better understanding and further demonstration of the existence of this biomineralization process.
Site 3 is characterized by the presence of well-layered, domical microbial mats. Gas is produced in abundance within the mats, which likely influences pore-water chemistry and might, in turn, influence the rate and the type of mineral precipitation.
Work is currently in progress to characterize the microbial diversity of the three sites through “next generation sequencing” methods, as well as characterization of the mineralogy and the isotopic composition of the carbonate and gypsum forming within the microbial mats. The ultimate goal is the better understanding of what role microbes play in the formation of ancient evaporitic sequences.
References
Alsharhan, A. S., and Kendall, C. G. S. C., 2003, Holocene coastal carbonates and evaporites of the southern Arabian Gulf and their ancient analogues: Earth-Science Reviews, v. 61, no. 3–4, p. 191–243.
Brauchli, M., McKenzie, J.A., Strohmenger, C.J., Sadooni, F., Vasconcelos, C., Bontognali, T.R.R., 2015. The importance of microbial mats for dolomite formation in the Dohat Faishakh sabkha, Qatar. Carbonates and Evaporates, p. 1–7.
Bontognali, T. R. R., Vasconcelos, C., Warthmann, R. J., Bernasconi, S. M., Dupraz, C., Strohmenger, C. J., and McKenzie, J. A., 2010, Dolomite formation within microbial mats in the coastal sabkha of Abu Dhabi (United Arab Emirates): Sedimentology, v. 57, no. 3, p. 824–844.
Bontognali, T. R. R., Vasconcelos, C., Warthmann, R.J., Lundberg, R., McKenzie, J.A., 2012. Dolomite-mediating bacterium isolated from the sabkha of Abu Dhabi (UAE). Terra Nova 24, 248–254.
Bontognali, T. R. R., McKenzie, J. A., Warthmann, R. J., and Vasconcelos, C., 2013, Microbially influenced formation of Mg-calcite and Ca-dolomite in the presence of exopolymeric substances produced by sulfate-reducing bacteria: Terra Nova, p. 1–6.
Illing, L. V., and Taylor, J. C. M., 1993, Penecontemporaneous dolomitization in Sabkha Faishakh, Qatar; evidence from changes in the chemistry of the interstitial brines: Journal of Sedimentray Research, v. 63, no. 6, p. 1042–1048.
Paulo, C., and Dittrich, M., 2013, 2D Raman spectroscopy study of dolomite and cyanobacterial extracellular polymeric substances from Khor Al-Adaid sabkha (Qatar): Journal of Raman Spectroscopy, v. 44, no. 11, p. 1563–1569.
Strohmenger, C. J., Shebl, H., Al-Mansoori, A., Al-Mehsin, K., Al-Jeelani, O., Al-Hoseni, I., Al-Shamry, A., and Al-Baker, S., 2011, Facies stacking patterns in a modern arid environment: a casa study of the Abu Dhabi sabkha in the vicinity of Al-Qanatir Island, United Arab Emirates, in Kendall, C. G. S. C., and Alsharhan, A. S., eds., Quaternary carbonate and evaporite sedimentary facies and their ancient analogues: A Tribute to Douglas James Shearman, Volume 43: Chichester, West Sussex, UK, Wiley-Blackwell, p. 149–182.
Vasconcelos, C., McKenzie, J. A., Bernasconi, S., Grujic, D., and Tiens, A. J., 1995, Microbial mediation as a possible mechanism for natural dolomite formation at low temperatures: Nature, v. 377, no. 6546, p. 220–222.
Wells, A. J., 1962, Recent Dolomite in the Persian Gulf: Nature, v. 194, no. 4825, p. 274–275.
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Novel Nanoparticle Doped Nanofiltration (NF) Polymeric Membranes for Ions and Heavy Metal Removal for Drinking Water and Water Desalination
Authors: Inshad Yousef Jum'H and Ahmad TelfahAvailability of clean water is one of the most urgent challenges for our societies. Practically, all water sources around the world are polluted to some degree due to a heavy influx of industrial effluents and domestic and agricultural wastes discharged into water sources.
Membrane technology has gained significant attention in the water treatment, because of its advantages such as cost effective, no phase change, easy fabrication and high removal efficiency. One of the most important environmental issues today is water contamination with heavy metals, due to their strong toxicity even at low concentrations. Heavy metals exist in water in colloidal, particulate and dissolved phases, and their occurrence in water is either of natural origin (e.g. eroded minerals within sediments and leaching of ore deposits) or of human origin.
Polymeric membrane filtration such as Nanofiltration are commonly used membrane process in heavy metals removal and multivalent and monovalent ions.
Hence, we have developing a low cost and high efficiency polymeric NF membrane. The commercial/conventional NF polymeric membrane development is moving in the direction of improving the cross-linking chemical bonds, optimizing the effective porosity, and searching for better polymer groups.
Most NF membranes are charged, and hence, they have a higher rejection to multivalent ions (heavy metals) than to monovalent ions; therefore, selective partition of ions is possible through electrostatic interaction. However, for heavy metal removal to lower ppm values, the surface charge of the desired polymeric membrane has to be enhanced. Our new innovative idea is to increase the surface charge of the NF polymeric membrane; with this improvement we add a new dimension of enhancement to the NF polymers. We have doped NF polymeric membranes with selectively metallic nanoparticles, which will be actively driven and oriented with respect to the surface vector of the membrane and its pores and then therefore the surface charge of the membrane will be significantly enhanced, the effective surface area and the pores sizes will be increased due to hydrophopic interactions between the coated magnetic nanoparticles and the heavy metal ions removal through adsorption in addition to the traditional steric effect and Donnan exclusion. As a consequence consequently the overall process of heavy metal removal will be significantly improved in every direction, which will directly affect the filtration quality, efficiency and the cost.
We have prepared the NF polymer chemically, the doping process with the selective metallic nanoparticles performed with the help of a selective electromagnetic pulse sequence. Characterisation with dedicated analytics based on analytical tools such as X-ray photo-emission spectroscopy (XPS), scanning electron microscopy (SEM), attenuated total reflection infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM) showed an evidence of noticeable increase in surface charge, surface roughness and density of porosity. XPS measurements revealed that nanoparticles are bonded to the polymer strand forming vibrating polymeric nano-chains. As a sequence, the obtained NF polymeric membrane is a novel material with enhanced intrinsic properties for monovalent, multivalent ions and heavy metal removal, which is expected to have significant influence in developing filtration and treatment membrane for drinking and ultra-grade water as well as for water desalination.
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Effects of Environmental Factors on Dust Particle Adhesion on Glass Substrates
Authors: Bing Guo, Eugene Chen and Hong LiangQatar is a dessert country full of solar resource to be further exploited. Despite the fact that Qatar has abundant petroleum resources, the first major solar power plant is expected to operate by 2016. Several projects related to solar power plants are also ongoing as well, which indicates that electricity generated by solar power will become more important and gradually have higher percentage among total electricity production. However, one of the major issues of PV power system is the dust soiling on photovoltaics (PV) panels due to the dusty weather conditions in Qatar. The dust soiling on PV panels has been confirmed to cause a significant performance loss due to the dust deposited on the surface of PV panels resulting in blocking the transmission of light. The performance loss can be from 5% up to 35%. Maintaining the surface with minimum dust soiling will be crucial to keep PV panels performing at higher efficiency.
This research aims to investigate the effects of environmental factors on dust particle adhesion of common materials used at Doha as glass windows and solar panels, among others. The main scientific question is to how the dust particles are attached to the surfaces of different morphology. From Rumpf and Rabinovich theory, the surface roughness of substrate has a significant impact on adhesion force of particles on surface. Other theories such as Johnson-Kendall-Roberts (JKR) and Derjaguin-Muller-Toporov (DMT) theories all assume that surface of particle and substrate are atomically smooth, which does not take surface roughness into consideration. However, there are surface roughness in nanoscale existed on both surfaces of particles and substrates. The surface asperity is assumed to be hemisphere on the substrate for model development. When particles are attached to substrate, the contact area actually reduces due to the existence of surface asperity of substrate and roughness of dust particles. Since the contact area is reduced, the adhesion force of particles reduces.
This research is to investigate the effects of environmental factors on adhesion of dust particles on glass substrates. The factors include Doha's climate such as temperature, humidity, wind gust, and among others that may contribute to the change in surface morphology of glass substrate. Surface roughness and morphology of glass substrates is evaluated by atomic force microscope. Morphological evaluation of dust particles is carried out using microscopic techniques such as optical microscope, scanning electron microscope. The particle analysis of optical images is conducted by using image-processing software ImageJ, which can provide the detailed information of shape, diameter, and size distribution of dust particles. The comparative study of adhesion of particles in terms of particle area density is conducted. The purpose of the study is to evaluate the soiling tendency or dust adhesion of glass substrates with various surface conditions. The result of dust adhesion of glass substrate is shown in terms of particle area density. The Results indicate that optimization of surface roughness could lead to better control of dust adhesion. The research is expected to give more fundamental study on dust to mitigate the dust soiling on PV panels.
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2015, A Year of Climate and Air Quality Anomalies
Authors: Mohammed Ayoub, Luis Ackermann, Adam Skillern and Jennifer StricklandWe report on a number of climate and air quality anomalies during 2015 and their potential impacts on human health, solar power generation and water security in Qatar and the wider region. The anomalies include a strong cut-off low pressure system and accompanying sand-storm in early April, elevated Sea Surface Temperatures (SST) from early summer through October in the Arabian Gulf, substantially higher year-on-year particulate matter concentrations (PM10 and PM2.5) in Qatar, and the development of two late season record strength cyclones in the Arabian Sea.
The impacts of climate change and air quality on sustainable development and human health are important considerations for all countries. The manifestations of climate change may differ from region to region, but the effects of a warming anomaly in the world's oceans, known as El Niño, has global reach. We present an analysis of surface observations, upper air and satellite data over Qatar and the GCC that relate the occurrence of these anomalies to the development of El Niño within the context of a changing climate.
The summer of 2015 saw increased ambient temperatures, dew point temperatures (a measure of relative humidity) and SST, compared to climatological averages, throughout much of the region. The July heat wave [Schär, 2015] resulted in temperatures in excess of 45C and SST exceeding 34C on July 31st. We report a substantial increase in particulate matter concentrations in the Doha urban area, as high as 20%-50% higher than the same period in 2014, during the summer months and into late October and early November. The higher concentrations of particulates are linked to increased evaporation and flux of sea salt particles during the warmer summer and their growth by interaction with emissions from the urban environment.
Tropical cyclones Chapala and Megh, developed one week apart in late October and early November, and were unprecedented in the historical record. Tropical cyclone Chapala developed over the warmest ever-recorded sea surface temperatures in the Arabian Sea and intensified to a Category 4 storm, causing severe damage.
The Southwest Monsoon keeps tropical cyclones from forming in the Arabian Sea for much of the year, allowing only a short season from May to early June before the monsoon arrives, and another short season in late October through November after the monsoon has departed. Arabian Sea tropical cyclones during the pre-monsoon period in May and June have become stronger over the past thirty years owing to a reduction in vertical wind shear brought about by dimming of sunlight from air pollution particles primarily emitted in India [Evan et al., 2011].
[Evan et al., 2011] also speculated that continued growth in air pollution emissions might also reduce wind shear in the post-monsoon October-November period, thus increasing the likelihood of development of intense tropical cyclones during that time. This is corroborated by evidence of the substantially higher year-on-year particulate matter concentrations in Doha presented earlier and the development of the two tropical cyclones in October and November.
Finally, we correlate the observed anomalies with projected climate trends to predict the contributions from climate change and air quality to human health impacts as well as those related to solar power generation and water security in Qatar and the region.
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Tropospheric Thermodynamic Behavior Over Qatar
Authors: Luis Ackermann, Mohammed Ali Ayoub, Adam Skillern, Dunia Bachour and Daniel Perez-AstudilloUnderstanding the mechanisms driving the development of the Planetary Boundary Layer (PBL) and the Subtropical Subsidence Inversion (SSI) over Qatar is essential for accurate prediction of surface meteorology and air quality. Using the vertical backscatter profile of the atmosphere from a ceilometer located at Qatar Foundation, coupled with a novel Layer Identification Algorithm (LIA) developed by scientists at QEERI, a continuous time series of the PBL and SSI has been constructed. LIA was developed in response to limitations in the original software from the ceilometer, that was only able to analyze data up to 4 km altitude, but radiosonde observations indicated the existence of the SSI at higher altitudes (between 4.5 and 8 km above sea level). LIA has been validated against in-situ measurements through spatial and temporal coincident radiosonde launches by QEERI (more than two years of weekly measurements). The LIA algorithm uses image recognition methods to identify boundary layers not only by their vertical characteristics; but also by their temporal and spatial signatures. The algorithm was written in Python and is designed to process the ceilometer's output data in real time or as a post-processing step. A short conceptual description of the algorithm's structure will be included in the methodology.
During the winter months the mean PBL depth in Doha was found to be higher compared to the summer months; in addition, the diurnal amplitude was higher during winter. Apart from seasonal variations in the PBL depth behavior, short term ?uctuations in the daily signature of the PBL structure were observed; with some days exhibiting a well-developed PBL followed by a day with no significant PBL variation. This behavior of the summer PBL (lower daily mean depth and lower diurnal amplitude relative to winter) is explained by two factors. An increase in the intensity of the sea breeze circulation; coupled with intense temperatures and humidity, the latter increases the energy ?ux towards latent heat. As a consequence, the development of the PBL is diminished during the summer. On the other hand, It was observed that the SSI is strongest during the summer months. The strength was established quantitatively via temperature inversion from the weekly radiosondes and qualitatively by continuity via LIA output. In addition to seasonal variations, the SSI exhibits short term fluctuations; in some occasions with height variations on the order of 2 km in three days. The details of the mechanism driving the SSI behavior are been studied using global circulation meteorological models.
The behavior of the PBL can exacerbate poor air quality events. This can be even worse in the case of Qatar; since during the months of higher photochemical activity (because of increased surface insolation, temperature and humidity) the PBL depth tends to be lower, therefore increasing the concentration of emitted pollutants (either anthropogenic or biogenic). Therefore, understanding the PBL and SSI seasonal and diurnal behavior is critical for predicting surface atmospheric conditions, as well as occurrences of poor air quality. This knowledge will help define possible mitigation strategies and inform urban planning and sustainable development.
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Road Accidents and Fatalities in Qatar: Is it the Environmental Factors to Blame?
By Wafaa SalehThis paper is aiming at raising awareness, informing decision makers and informing the transportation community of the implications of road accidents and high accident rates and severities in Qatar and similar Gulf countries. The paper is also recommending to adopt an integrated approach with a set of measures and actions to policy makers in Doha, including environmental measures which can aim at improving pedestrian safety and reducing accidents while walking or crossing the roads in urban areas in Doha. The recommendations will be applicable for implementation in other similar cities in the region.
The statistics of those killed as a result of road traffic accident is very alarming and comparable to those caused by communicable diseases as shown in Table 1.1. Although road traffic accidents affect all age groups, but its fatality rate is conspicuously highest among young people. In fact, it is consistently one of the top three causes of death for people between the ages of 5 and 44 years (WHO, 2009). These unprecedented fatality rates has prompted the World health Organization (WHO) to call for urgent action to be taken to curb this menace or else the fatalities could rise to become the fifth leading cause of death by 2030 (WHO, 2009). Table 1.1: Leading causes of death, 2004 and 2030 compared
(Source: Peden et al., 2004)
These safety concerns are worldwide; the UK Department for Transport reports that in 2011, the fatality rate for pedestrians has increased by 12% compared to 2010. In the United States, statistics show that there are 5,000 killed and 64,000 injured pedestrians in vehicle accidents annually. Other western and Eastern countries also face similar problems and concern about pedestrian traffic accidents. In order to manage and improve pedestrian accidents, it is important to have a good understanding of pedestrian movements while walking and crossing the roads.
The fatality rate of road traffic accidents vary geographically depending on several factors which may include: the population of the place (i.e. level of crowdedness); environmental factors (e.g. its quality of road networks, design of the roads); economy of the region (e.g. income of the people); government policies of implementing road safety regulations etc. For instance, road traffic accidents have claimed more lives in North America than any other geographic region. Pedestrian accidents are of major concern in Qatar as well as in other Gulf countries that could discourage individuals to walk. Statistics show that the large majority of pedestrian deaths occur in urban areas. It has been claimed that pedestrians are involved in more than 25% of total deaths in these accidents. Pedestrian accidents in urban areas occur largely on the main roads where pedestrian traffic is more frequent and the vehicle traffic is heavier or faster; all of which make crossing action more difficult. Infrastructure, road design as well as other environmental factors all contribute to the volume of pedestrian, as well as other types’ of accidents.
Despite effort by the Gulf governments to improve road safety regulations, road traffic accidents are becoming increasingly prevalent in in these states, thereby, constituting a serious public health problem (Barrimah et al., 2012; Ansari et al., 2000; Bener & Jadaan, 1992; Ofosu et al., 1988). In fact, researches have shown that road traffic accidents are the major cause of morbidity and mortality at a rate that is comparable to heart diseases and cancer (WHO, 2009; Al Ghamdi, 2002 & 2003). In Saudi Arabia, road traffic accidents have been found to be second major health problem, after infectious diseases (Mufti, 1983). Since the oil boom in 1973, the Gulf states have experienced rapid expansion of their economy and urban development of most of its cities (Ofosu et al., 1988). Again, there has been rapid population growth triggered by its economic prosperity causing an influx of foreign workers (Ansari et al., 2000; Ofosu et al., 1988). The Gulf states are also attractive destinations to a large number of employees because of the high salaries and free income taxes in these states. Moreover, there have been an increased motorization of the highways and rapid expansion of road networks in all Gulf states (see for example Ansari et al., 2000; Ofosu et al., 1988). This is because motor vehicles are the principal means of transportation in these countries due to the convenience and speed they offer in facilitating the movement of people and goods to their various destinations (Ansari et al., 2000). Road transportation also has positive impacts on both the nations and individuals by enabling increased access to economic activities, job opportunities, education, recreation and health care service.
In Doha, as in other Gulf cities the mixed population composition and backgrounds and different walking and crossing behaviour add to the complexity of understanding pedestrian behaviour. Land use characteristics in these countries also have to be considered as a major contributor to accidents in these countries. Therefore, pedestrian flows have to be managed in a more efficient way in order to consistently cut the number of fatalities.
To address the above, the paper is designed to investigate the main factors that influence pedestrian behaviour at congested locations in urban areas in Doha and the appropriate way forward to influence this bahaviour. The paper presents an in-depth investigation and characterisation of pedestrian interaction with motorised traffic. The way forward to overcome some of the discussed factors will also be proposed.
References:
Al-Ghamdi, A. S. (2002) ‘Pedestrian–vehicle crashes and analytical techniques for stratified contingency tables’, Accident Analysis and Prevention, 34(2): 205–214.
Al-Ghamdi, A. S. (2003) ‘Analysis of traffic accidents at urban intersections in Riyadh’, Accident Analysis and Prevention, 35(5): 717–724.
Ansari, S., Akhdar, F., Mandoorah, M. and Moutaery, K. (2000) ‘Causes and effects of road traffic accidents in Saudi Arabia’, Public Health, 114(1): 37–39.
Barrimah, I., Midhet, F. and Sharaf, F. (2012) ‘Epidemiology of Road Traffic Injuries in Qassim Region, Saudi Arabia: Consistency of Police and Health Data’, International Journal of Health Sciences, Qassim University, 6(1): 31–41.
Bener, A. and Jadaan, K. S. (1992) ‘A perspective on road fatalities in Jeddah, Saudi Arabia’, Accident Analysis & Prevention, 24(2): 143–148.
CNN World Report (2008) http://money.cnn.com/2008/03/05/news/economy/AAA_study/ (Accessed on 21st June 2012).
International Road Federation (2008) World Road Statistics 2008, Data 2001 to 2006. http://www.irfnet.org/files-upload/stats/2008/WRS2008_Publication.pdf (Accessed on 21st July 2012).
Mufti M. H. (1983) ‘Road traffic accidents as a public health problem in Riyadh, Saudi Arabia’, Int. Assoc. for Accident and Traffic Medicine, 11: 65–69.
National Statistical Office (2011) Central Department of Statistics, Ministry of Economy and Planning, Published by the Saudi Arabia Monetary Agency. http://www.indexmundi.com/saudi_arabia/population.html (Accessed on 24th July 2012).
Ofosu, J. B., Abouammoh, A. M. and Bener, A. (1988) ‘A study of road traffic accidents in Saudi Arabia’, Accident Analysis & Prevention, 20(2): 95–101.
Peden, M., Scurfield, R., Sleet, D., Mohan, D., Hyder, A., Jarawan, E. and Mathers, C. (Eds.) (2004) ‘World Report on Road Traffic Injury and Prevention’, World Health Organization, Geneva.
World Health Organization (2009) ‘Global Status Report on Road Safety: Time for Action’.
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Methanotrophically Mediated Bioaggregation to Control Sand Dust in Qatar
More LessSandstorms are commonplace in many parts of the world including Qatar, these storms have significant negative impacts on the economy, environment, infrastructure, and public health. Traditional prevention techniques use chemical stabilizers and cementing agents; however, their application is not only expensive, but may also have negative impacts on the environment and public health. Recently steep regulations on chemical grouts from Japan and the United States has caused many countries to follow suit and propose bans. In turn organic polymers and microbial biogrout have been proposed. However, organic polymers still have significant negative impacts on the environment; while biogrout has proven effective, it has not been tested for surface stabilization and releases harmful ammonia as a byproduct. Our research team has proposed using native extracellular polysaccharide (EPS) producing bacteria, specifically methanotrophic bacteria, for bioaggregation. EPS, sugars formed by the cell and then released outside the cell wall, make up much of the adhesive characteristics of biofilm and have been known to naturally form microbial crusts in Chinese desert sand. EPS is composed of a wide variety of sugars, not all of which are useful for stability, hence multiple species and their EPS must be tested. The proposed technique would involve application of an EPS producing methanotrophic bacterial culture to the sand's surface, or, application of the liquid culture followed by application of purified EPS. Methanotrophic bacteria are capable of using Methane as a carbon source and can produce large amounts of EPS and have been widely studied. The preference is for native methanotrophic bacteria to be used, to prevent introduction of non-native species or genes, and to minimize the disruption to the native ecosystem. We have collected native methanotrophic bacteria from Qatar sand. Samples of sand were incubated in Nitrate Mineral Salt (NMS) media under a 1:1 headspace ratio of air to Methane, and then streaked onto agar plates of the same media. The plates showed growth and EPS production. Since the media contains no carbon source the only accessible carbon source is the methane in the headspace so the bacteria can be assumed to be Methanotrophic. This will be confirmed along with determining species identifications through 16S rRNA Gene Amplicon Sanger Sequencing of the isolates; however, at the time of submission for this abstract sequencing and interpretation of the data are still underway. Until native methanotrophic bacteria can be identified and researched, two well studied strains of Methanotrophs – Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b – are being used for preliminary EPS testing. Application of purified EPS, extracted with an Ethanol precipitation extraction method, to sand has shown signs of significant aggregation, along with increases in shear strength. Once a strain of bacteria is chosen by the research team, and the EPS production optimized, a lab scale bioreactor will be built to produce large amounts of EPS for lab scale sand stabilization studies. Lab scale studies will monitor time dependent changes in shear strength during application, microbial community changes, and ability to withstand critical threshold wind velocities. Future plans include field scale studies and the construction of a fluidized bed bioreactor for production of the liquid medium and EPS. Methanotrophic bacteria are easily adapted to large bioreactors and in situ applications. Bioaggregation with EPS producing bacteria would potentially provide an environmental friendly application for the prevention of sandstorms, utilizing methane – an indigenous resource to Qatar – for cost saving benefits.
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Necessity of the Adaptive Comfort Standard for the Middle East in the Times of Rising Energy Use
Authors: Madhavi Indraganti, Djamel Boussaa and Somayeh AsadiMiddle East (ME) supplies more than 47% oil exported in the world (IEA 2013) and has highest energy self-sufficiency in the world. It includes 12 countries and has a population of 205 million in 2010, which increased by about 61.4% from 1990 (IEA 2010). Its energy demand has increased astronomically at the rate of 7% per year, since 1971–2013, faster than in any other region in the world. Buildings majorly contribute to this. Building energy (residential, commercial and public use buildings) use in the ME has increased by about 46% in the period 2003–13 (IEA 2010).
Ironically ME houses only about 3% of the world's population, but it contributes to 13% of global CO2 emissions. Understandable, its per capita CO2 emission is one of the highest in the world at 7.53 tons of CO2/capita, 68% higher than the world average. Therefore improving the energy efficiency remains a key challenge for the region. International Energy Agency (IEA) identifies the development and enforcement of building energy codes coupled with energy consumption data generation as the top energy efficiency policy recommendations for this region (IEA 2014).
Qatar's per capita energy consumption is one of the highest, consuming 30.184 TWh as of 2012 (IEA 2012) Buildings contribute majorly (80%) to this, with air-conditioning taking a lion's share. With the absence of custom-made energy/thermal comfort standards, the buildings tend to follow western standards meant for colder climates verbatim. Cheap energy availability and tariffs exacerbate this practice (Fattouha and El-Katiri 2013). Often times, energy analysis and conservation come as postmortem ideas than at the design stage. And the energy subsidies often prove to be unrealistic and unsustainable in the long run.
Qatar has little research on occupant thermal comfort and preferences in buildings. Energy efficient building design necessitates this. As part of large energy conservation web tool design for Qatar, we conduct year long occupant surveys in office buildings to understand the nature of the building stock and occupant thermal comfort and preferences along side their thermal adaptations.
Saudi Arabia stands sixth in world's oil consumption and already uses a quarter of its own production. Building energy consumption in Saudi Arabia went up astronomically by 60.8% in five years from 2007 to 2012. Energy analysts argue that Saudi Arabia could turn into a net oil importer by 2030 if current demand, growth patterns continue. Air conditioning majorly contributes to this. Recent research posits that the building envelope codes have a limited role to play in reducing energy consumption (Radhi 2009).
Saudi building code specifies two design temperatures of 20 °C and 25.5 °C for winter and summer, for all climate and building types, much similar to the building codes of other countries like UAE (SBCNC 2007). Relying on Fanger's heat balance model (Fanger 1972), the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard -55 (1992) formed the basis for this. This Standard is long since superseded (ASHRAE 1992).
Environments designed based on this model produce thermal monotony (uniform indoor temperatures yearlong), with the indoor environments delinked from the outdoors. It ignores the local climate, clothing, culture or comfort practices of Saudis. Researchers all across the globe criticized such rigid and unsustainable indoor temperatures.
The Adaptive model of Thermal Comfort on the other hand hinges on the field studies in real life buildings. People in their everyday environments are studied in order to develop the temperature standards that truly represent local climate, people, their comfort practices and adaptation mechanisms. Saudi Arabia is yet to develop its Adaptive Thermal Comfort Standards (ACS) (Nicol and Humphreys 2009) (CIBSE, (The Chartered Institution of Building Services Engineers) 2006, Indraganti, et al. 2014) (ASHRAE 2010) (ASHRAE 2010).
The potential of occupant's adaptation and the ACS is in producing sustainable indoor environments is long since been recognized. Therefore, this presentation highlights the necessity of the Adaptive Comfort Standards for the ME in the context of its growing energy concerns. It relies on the results of the first field studies we have conducted in Japan and India, KSA and Qatar and also draws heavily from the current research around the world.
References
ASHRAE. ANSI/ASHRAE Standard 55–1992, Thermal environmental conditions for human occupancy. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., 1992.
ASHRAE. “ANSI/ASHRAE Standard 55–2010, Thermal environmental conditions for human occupancy”. Standard, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc, Atlanta, 2010.
CIBSE, (The Chartered Institution of Building Services Engineers). “Environmental Design Guide, Vol. A”. London, 2006.
Fanger, P. O. Thermal Comfort, Analysis und Applications in Environmental Engineering. New York: McGraw-Hill, 1972.
Fattouha, Bassam, and Laura El-Katiri. “Energy subsidies in the Middle East and North Africa”. Energy Strategy Reviews 2, no. 1 (2013): 108–115.
IEA. “Regional Energy Efficiency Policy Recommendations, Regional Energy Efficiency Policy Recommendations Arab-Southern and Eastern Mediterranean (SEMED) Region”. 2014.
IEA. “Energy balances of non-OECD countries”. International Energy Agency, 2010.
IEA. “Energy balances of non-OECD countries”. International Energy Agency, 2012.
Indraganti, Madhavi, Ryozo Ooka, Hom B Rijal, and Gail S Brager. “Adaptive model of thermal comfort for offices in hot and humid climates of India”. Building and Environment 74, no. 4 (April 2014): 39–53.
Nicol, Fergus, and Michael A Humphreys. “New standards for comfort and energy use in buildings”. Building Research & Information 37, no. 1 (2009): 68–73.
Radhi, H. “Can envelope codes reduce electricity and CO2 emissions in different types of buildings in the hot climate of Bahrain?”. Energy, 2009: 34(2009)205–215.
SBCNC. Saudi Building Code Energy Conservation Requirements: 601. 601, Saudi Building Code National Committee, Riyadh: Government of Saudi Arabia, 2007, 198.
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Identifying Current BIM Practices in Qatar and Proposing a Framework for Whole Life Cycle BIM Processes
Authors: Mian Atif Hafeez, Vladimir Vukovic, Racha Chahrour, Mohamad Kassem and Nashwan DawoodThe research is part of a wider project aimed to develop a whole lifecycle information flow approach enabled by BIM protocols and technologies for Qatari construction industry. We consider the lifecycle information flow as enabler of a consistent and continuous use of building information from design, through construction, to the facility management stage. Building Information Modeling (BIM) is increasingly used by the Architecture, Engineering, Construction and Operation (AECO) professionals around the world. BIM has proven and potential benefits to facilitate Whole Life Cycle (WLC) information flow described above. It is generally accepted fact that AECO industry is fragmented in nature. Using BIM for WLC information flow is seen as one of the potential solutions to contribute towards a more cohesive AECO industry.
Within the global construction sector, Qatar's construction market is one of the fastest growing in the world throughout the next decade in alignment with the Qatar National Vision 2030. Currently ongoing and planned construction projects exceed US$220 billion (Kilani, 2014), e.g. Lusail City projects, new Doha Port, new Hamad International Airport, Qatar Rail project, Qatar National Museum project as well as construction of stadiums and related infrastructure projects ahead of the Qatar 2022 FIFA World Cup.
This paper aims to identify current BIM related practices, existing procedures, technology and standards being used in Qatar using qualitative data collection and analysis technique and then proposes a framework for BIM processes across whole life cycle of the project to facilitate whole life cycle information flow. 28 semi-structured interviews were conducted with different stakeholders (clients, contractors, consultants) involved mainly in design and construction project lifecycle stages in Qatar. Results of the conducted interview analyses are presented in relation to policy, people, process and technology (3P + T) pillars that have been proposed for use in Qatar.
The following key findings were reported by majority of the interviewees (values in brackets indicate the agreement percentage): (Vukovic, Hafeez, Chahrour, Kassem, & Dawood, 2015)
- Usage of FIDIC contract template (67%) and BS 1192:2007 BIM standards (60%) is prevalent on projects in Qatar. However, specific BIM information/standards should be developed at a government level for the Qatari construction industry (86%), including standard project stages with clear process maps (82%). Also in comparison to the situation in other countries, based on the examined literature, Qatari government should do more to drive the construction industry transformation by undertaking BIM related initiatives.
- BIM competency is usually a criteria for prequalification and selection during the procurement process (71%).
- Organizations in Qatar mostly use in-house BIM trained staff (75%).
- BIM roles are specifically defined in the contract (86%), BIM standards are required by contracts (68%), and should be enforced by contracts (75%).
- There is no need to create more BIM specific roles/positions (64%), but there is a need to upgrade the skills of people on BIM specific positions (89%). There is also a need to educate other project participants how to collaborate using BIM (96%). Such identified needs are similar to the situation in other countries covered by the literature review.
- LOD 300 is mostly required in design/construction stages of ongoing projects in Qatar (64%), which is the owners' responsibility (71%). The owner usually also initiates design changes (68%).
In alignment with the above findings this paper proposes a framework (Fig. 1) consisting of ‘Project DNA’, BIM Processes and Whole Life Cycle of the projects and their inter relationship. Future work will elaborate on the BIM processes and protocols and validate the proposed framework using case studies.
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Long Term Energy System Planning: to a 100% Renewable Energy System by 2050
Authors: Pieter Lodewijks and Jan DuerinckIntroduction: To date, a variety of studies have been published on the topic of long term energy system transition. Most studies on future energy systems, however, have a shorter time frame or adopt a supranational focus (e.g. the Energy Roadmap, 2011 or the World Energy Outlook, 2015). It then constitutes a sincere challenge to perform a national energy system transition study with as time horizon 2050 and covering a far-reaching transformation of the energy system.
VITO, together with the FPB (Federal Planning Bureau) and ICEDD, performed a study to scrutinise the transition of the Belgian national energy system towards a future mix entirely based on renewable energy sources. The focus on renewable energy sources and on building a national energy system completely running on renewable energy can be traced back to three main concerns:
- – Climate change: Renewable energy sources (RES) are a major instrument in the fight against climate change as RES do not release (net) greenhouse gas emissions.
- – Security of supply: Most renewable energy sources make use of technologies that ultimately derive energy from natural phenomena like wind, wave, tidal, sun, water, etc. Renewable electricity can be generated from wind power, wave, solar photovoltaics (PV), hydro, geothermal and biomass. Since most RES are then cultivated or naturally available within a nation's territory, RES can help to reduce Belgium's (and Europe's) growing dependence on imported fossil fuels. As a 100% RES based system is independent of imported fossil fuels, it goes without saying that security of energy supply should benefit from a transition to a 100% RES based system.
- – Economy/competitiveness: creating or expanding a renewable market with a considerable number of direct and indirect jobs can seem appealing. Moreover, an energy system entirely based on renewable energy presupposes considerable efforts in the field of energy savings to drastically diminish the amount of energy needed, which in its turn instigates the activity of a.o. the building sector (through e.g. Insulation, heat pumps, airco systems, etc.). Not only job creation can prompt economic growth, also cost cutting does. As to costs, (most) RES, once in operation, have no fuel costs and less maintenance is needed to keep them functioning (IEA, 2005). However, it is also worth noting that most RES today need subsidies to compete with other technologies. These subsidies should nonetheless decrease steadily over time because of the “learning by doing” process and economies of scale so as to reach a level playing field with the “old” fossil fuels whose prices, due to scarcity issues, will likely not stop increasing in the coming decades if no global action is taken.
The Integrated MARKAL-EFOM System) is an economic model generator for energy systems, which provides a technology-rich basis for estimating energy dynamics over a long-term, multi-period time horizon. Reference case estimates of end-use energy service demands (e.g. car travel; residential lighting and heating/cooling; steam heat requirements in industrial sectors; etc.) are provided by the user. In addition, the user provides estimates of the existing stock of energy related equipment in all sectors and the characteristics of available future technologies, as well as present and future sources of primary energy supply and their potentials.
Using these as inputs, the TIMES model aims at supplying energy services at minimum global cost (at minimum loss of surplus) by simultaneously making equipment investment and operating decisions. For example, an increased demand for electrical appliances in the residential sector due to population growth leads to a number of reactions.
First, it involves a choice of appliances as the market provides different types corresponding to different energy efficiency levels (energy labelling) at different costs. Second, the increased demand for electricity has to be met and either existing generation equipment is used more intensively or new – possibly more efficient – equipment must be installed. The choice of the model of the generation equipment (type and fuel) is based on the analysis of the characteristics of alternative generation technologies, on the economics of the energy supply, and on environmental criteria.
The cost minimisation approach covers the full time horizon, which involves comparing different costs at different points in time. For this purpose all costs are discounted to the base year, using a uniform (social) discount rate.
The TIMES model is less suited as a projection tool. The main purpose of TIMES is the analysis of alternative scenarios, i.e. the impacts of measures are evaluated by comparing two scenarios which have been constructed in a transparent and consistent manner. The approach is more normative from the point of view of the public authorities (prescribing what optimally should happen). Transparency is guaranteed by the explicitness.
Challenges of intermittent energy
When dealing with high penetrations of intermittent renewable energy sources like wind and solar, fluctuations in supply occur and prevail over demand fluctuations. In the case of solar energy, the decomposition of the yearly production profile comprises 3 components: first, day/night fluctuations, second, a long wave starting at close to zero levels in January, peaking in the summer months and ending at similar close to zero levels by the end of the year, and third, a pattern that looks purely random. For wind we observe many cycles, defining periods with low availability extending from a couple of days to a couple of weeks. Dealing in a correct way with the intermittent nature of wind and solar energy is a major challenge for developing renewable energy scenarios and the high share of renewable energies required several model improvements for which we defined specific model adjustments that are also applicable for TIMES models for other countries. Different approaches for dealing with intermittent energy can be thought of: a better integration of the Belgian network in a European network, installing back-up installations, implementing smart grids, using storage technologies, adapting demand to supply.
Storage options are included in order to represent different alternatives in dealing with the volatility of energy supply. So far, the only mass storage available in Belgium is the pumped water storage facility in Coo, representing a capacity of 5 GWh, allowing producing electricity at a power rate of 1.2 GW. Additional storage facilities are included in the model: day/night and seasonal storage options for electricity, electricity to hydrogen and hydrogen to electricity options (electrolysis and fuel cells) and hydrogen storage options.
Standard TIMES models consider 12 sub-periods in one year, representing 4 seasons and 3 daily levels: night, day and peak. Usually this distribution in twelve time slices is chosen to represent the variability in demand and one peak demand slice simulates a peak close to historical levels. Empirically it has been found that this level of detail is sufficient for dealing with fluctuations in demand when supply is steerable. However, when dealing with high penetrations of intermittent renewable energy sources like wind and solar, fluctuations in supply occur and prevail over demand fluctuations. In order to represent this in the model the number of time periods within one year has been extended to 78 periods, equivalent to 26 two-week periods and 3 daily levels. Results: The main goal of this study is to examine the feasibility and the impact of a 100% renewable energy target on the future Belgian energy system 63. Although the realisation of such a transformation within a 40-year perspective may at first seem highly ambitious in a nation rather poorly endowed with natural resources and possessing both a highly energy-intensive industry and an energy-greedy residential sector, it appears to be technically feasible.
1. Extensive electrification and almost 100% renewable electricity by 2030
Moving to a 100% renewable energy system implies a radical transformation of nearly all sectors of the economy. The model shows that the strongest growth of renewable technologies is concentrated in the period 2030–2050. Nevertheless, some sectors experience thorough impacts earlier on through high growth rates of renewable energy technologies. This is particularly the case in the electricity production sector, which has to be transformed almost completely into a renewable based sector by 2030, since investments in the power generation sector appear to be the least expensive. Furthermore, the results of the model indicate that a 100% renewable energy system needs extensive electrification, causing a doubling or even tripling of the current electricity production by 2050.
2. Energy imports strongly diminish, but remain important
Transforming the energy system into a 100% renewable system will require considerable investments in demand-side management technologies, storage capacities and energy production installations. On the other hand, a higher share of renewable energy or lower energy consumption implies less fossil fuel purchases, which may reduce the national external fuel bill. Indeed, it is evident that solar, wind, hydroelectric or geothermal energy production installations do not need fuel input to produce useful energy for final consumers. The only exceptions to this rule are biomass and electricity imports which will tilt the balance of payments. Even so, the share of total imported energy tumbles from 83% in the reference scenario to a range between 15% and 42% in the renewable scenarios.
3. Additional energy system costs are rather stable over the different scenarios
The energy system cost is the sum of all energy expenses in an energy system. It consists of variable, fixed and investment costs. We calculated that the increase of the energy system cost amounts to approximately 20% in 2050, or 2% of Belgian GDP in 2050 (GDP2050). The necessary power sector investments vary between 1.0% (scenario focusing on demand decrease) and 1.7% (PV and WIND) of GDP2050. In conclusion, we can say that from today up to 2050, 300 to 400 billion € of investments are needed to transform our current energy system into a 100% renewable energy system.
4. Creation of additional employment
Although total system costs may appear considerable, one has to bear in mind that orienting our energy future towards renewable energy sources also entails benefits. One of those positive effects is further analyzed in the course of this study: the creation of additional employment through the renewable value chains. It was estimated that, by the end of 2030, this effect would create 20 000 to 60 000 additional full-time equivalent jobs compared to the reference scenario. At any point in time, the renewable scenarios create more full-time equivalent jobs than the reference scenario. The high end of the interval is taken in by the PV scenario, given that it necessitates many discrete panel installations combined with a large installation component in PV employment.
5. A new paradigm on energy perception
A new paradigm is arising in the way we think about energy. In a world without excess overcapacity of intermittent renewable energy sources and only limited access to biomass and geothermal energy, long-term (seasonal) storage is becoming extremely expensive. This leads us to believe that, in a cost-optimal modelling approach, a transformation of the energy system towards abandoning strict equilibria and replacing it by installing overcapacity in intermittent renewable energy sources is to be preferred. In other words, it may be more cost-efficient for the Belgian society to adapt in a certain way to the variability of the solar energy flow instead of trying to store enough energy in order to keep our current socio-economic paradigm unchanged. This in turn can impact the current industrial organisation towards more seasonal production oriented sectors, using necessary energy commodities such as electricity only during the cheapest periods of the year when e.g. sunlight is abundantly available and closing down during the darker winter months. This flexibility within the industry can then be perceived as having the same effect as a giant battery in which electricity can be stored in the aggregation state of e.g. steel.
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Petroleum Geochemistry Serving Oil Fields Production
Authors: Frank Haeseler, Fatima Mahdaoui and Ahmad AldahikIn the oil industry when commingled wells are producing from different reservoirs (different geological layers) or even when production wells are connected to a common flowline, it is often necessary to quantify the fluid origin. This is a way to obtain material balance and to allocate the oil production. Production allocation is particularly important for a better reservoir management (history matching with the reservoir models). Several methods can be used aiming to determine the fluid flow like the Production Logging Test (PLT) or geochemical tools. The geochemical techniques (e.g. molecular fingerprinting of oil) are based on specificities of the oil composition and represent a profitable alternative method (less risk, no well intervention, no production losses, cost savings and higher frequencies) to PLT. The geochemical differences affecting oil composition can be attributed to many reasons: different source rocks, process of migration and filling histories, reservoir communication leading to oil mixture, and several in-reservoir alteration processes. Therefore, chemical differences between the oils are always existing can be used to determine and quantify the contribution of each fluid source.
Molecular fingerprinting using high resolution gas chromatography is a reference technique widely used for geochemical production allocation. This conventional type of techniques allows discriminating very similar fluids even so similar fluids as condensates (Sabatier et al., 2015). Nevertheless alternative techniques should be explored.
In the present work we investigated the possibility to discriminate oils form the same fields according to possible differences in composition of aromatic compounds. Specific geochemical analyses where performed in Doha in a joint Qatar Petroleum – Total project. The analytical approach used was Gas Chromatography coupled with Mass Spectrometry and a typical chromatograph is shown in figure 1.
Figure 1: gas chromatogram of the aromatic fraction of a petroleum sample (m/z 128: Naphtalene, m/z 142: methyl-naphtalenes, m/z 156: dimethyl-naphtalenes, m/z 170: trimethyl-naphtalenes, m/z 184: tetramethyl-naphtalenes, m/z 198: pentamethyl-naphtalenes).
As shown in an example presented in figure 2, the reservoirs from the studied fields coming from all around the world could be discriminated considering the composition in diaromatic hydrocarbons. This discrimination is possible considering both the height of the peaks or their surface.
Figure 2: comparison of the proportion of diaromatic hydrocarbon in the oils from different reservoirs of the same field.
The present study concerns the ability to discriminate oils according dicyclic aromatic hydrocarbons, but the same conclusions applies to tri, tetra and penta aromatic compounds (results not shown).
The results shown in the present study clearly allow envisaging fast analysis techniques based on aromatic hydrocarbons detection. This opens the way for future work focusing on quantifying such kind of compounds (involving quick separation techniques and smart detection methods). Literature reference: Sabatier L., Haidar F., Mahdaoui F., Dessort D., and Philippe Julien, 2015, Gas Reservoir Management: How to improve Gas Production Allocation per Reservoir in commingled Wells using Geochemistry Technology?, Proceedings of the International Petroleum Technology Conference, December 6th to 9th, Doha, Qatar.
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Metasurfaces for Far-Field Wireless Power Transfer and Energy Harvesting
By Omar RamahiThe concept of electromagnetic energy harvesting and wireless power transfer had been proposed more than half a century ago. In all published works related to electromagnetic energy collection, classical antennas have been used while the focus shifted to the rectification circuitry. Recent works showed that the weakest link in the traditional energy harvesting chain is the antenna itself. Here, we show that metasurfaces provide a viable alternative to classical antennas yielding efficiencies approaching unity. This presentation will be confined to the microwaves frequency regime.
Far-field wireless power transfer (WPT) is a relatively old concept where antennas are used to transfer power between two distant points. WPT perhaps dates back to Tesla but it was Brown in the 1950s that demonstrated its viability [1]. In recent years, WPT has been reconsidered as practical means to transfer power from outer space where satellites collect solar power with high efficiency using photovoltaic technology and then convert the power to microwaves for beaming to antenna farms at specific locations on earth. This would facilitate availability of plenty of power everyday throughout the year.
Conventional antennas have been the traditional microwaves transducers used for WPT applications. Conventional antenna types include log-periodic, patch, dipole or any of the varieties of antennas that were conceived in the past 100 years. Almost all antennas that were considered for WPT applications were designed in the first place for communication applications where traditional parameters such as gain, directivity and efficiency were considered the most critical. For WPT applications, at the transmission stage, the gain, directivity and efficiency play an important role in the design. At the receiving stage, however, the primary concern is to collect as much power as possible per footprint and based on specific polarization and incident angle. In applications of classical communication antennas, the real estate or footprint of the antenna has partial relevance. For instance, a patch printed antenna occupies some space on copper but its antenna parameters assume the antenna is present in a larger empty sphere. In other words, its functional space extends beyond its size.
Metamaterials are made of a three-dimensional ensemble of electrically-small resonators. Metasurfaces are considered as a two-dimensional version of metamaterials. The interesting and desired properties of metamaterials or metasurfaces are achieved when all elements of the ensemble operate at their resonance frequency (for simplicity, we assume all elements are identical). The resonance of each particle of a metamaterial or metasurface is fundamentally indicative of its ability to store energy. Metamaterials, therefore, can be effective energy collectors. This does not come as a surprise since metamaterials have been shown to be highly effective absorbers. However, in the case of absorption, the absorbed energy is mostly dissipated in the dielectric host. For the effective use of metamaterial as energy harvesters or collectors, not only the energy absorption is of high importance but also channeling the absorbed energy into energy collection channels is critical.
In this paper we demonstrate that metasurfaces can indeed be effective electromagnetic energy harvesters and can provide energy harvesting efficiency appreciably higher than what classical antennas can achieve. The effectiveness of the metasurface for energy harvesting arises from the close proximity between the electrically-small resonators that constitute the metasurface. While the spacing between electrically-small resonators is critical to achieve homogenization for classical metamaterial applications, in energy harvesting as the case in our work, the spacing between elements allow for careful input impedance tuning of all elements, thus enabling highly efficient energy transduction [2].
In this talk, we present metasurfaces composed of different types of resonators including split-ring resonators, electric-inductive-capacitive resonators, complementary split-ring resonators and dielectric resonators. We show that it is possible to achieve energy absorption with approximately 100% efficiency. In fact, using the concept of stacking of metasurfaces (which does not necessarily lead to metamaterials), it is possible to achieve efficiencies significantly higher than 100% as based on the efficiency definition provided in [3–4]. Simulation and experimental results will be provided to fully validate the feasibility and practicality of electromagnetic energy harvesting using metasurfaces.
References:
[1] Brown, W. C., “The History of Power Transmission by Radio Waves,” IEEE Transactions on Microwave Theory and Techniques, Vol. 32, No. 9, pp. 1230–1242, 1984.
[2] Almoneef, T. and O. M. Ramahi, “Split-Ring Resonator Arrays for Electromagnetic Energy Harvesting,” Progress in Electromagnetic Research B, in press.
[3] Ramahi, O.M., T. Almoneef and M. AlShareef, “Metamaterial Particles for Electromagnetic Energy Harvesting,” Applied Physics Letters, Vol. 101, No. 17, pp. 173903–173908, 2012.
[4] Almoneef, T and O. M. Ramahi, “A 3-Dimensional Stacked Metamaterial Array for Electromagnetic Energy Harvesting,” Progress in Electromagnetic Research B, Vol. 146, pp. 109–115, 2014.
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Usefulness of In-Situ Synchrotron Study on Scale Formation during CO 2 Corrosion of Mild Steel: A Review
More LessDespite the availability of the detailed knowledge about the chemical, electrochemical and transport processes associated with the formation of ferrous carbonate during CO2- corrosion of mild steel, information available about the mechanism of early nucleation stages of FeCO3 (siderite) film formation was only speculative. In depth knowledge related to the early stage nucleation of siderite scale and its subsequent development and gradual growth were revealed only recently by judicious exploration of in-situ synchrotron based experimentation. Moreover, application of in-situ synchrotron x-ray diffraction technique rendered ability to monitor the gradual real time growth of FeCO3 scale with the efficacy of simultaneous controllability of the corrosion conditions electrochemically. This work shades light on how in-situ synchrotron study revealed apparent mysteries related to formation & growth of siderite scale during CO2- corrosion of mild steel. Keywords: In-situ synchrotron, CO2-Corrosion of mild steel, Nucleation mechanism during CO2- corrosion.
Figure 1 (a) and (b) illustrate the photograph and schematic of experimental set up for in-situ synchrotron X-ray diffraction experiments using the powder diffraction Australian beam line.
Figure 2 shows the anodic current as a function of time in a potentiostatic test in the NaCl solution at pH 6.3 (pCO2 = 1bar) and an applied potential of − 500 mV (vs SCE), together with the intensities of the Fe and FeCO3 signals from the in-situ synchrotron XRD [1]. There is a clear peak in the current transient, with the XRD results showing FeCO3 formation during the increasing portion of this transient and then a rapidly decreasing rate of FeCO3 formation as the anodic current decreases towards the end of the test, indicating the growth of a protective surface scale. In these studies, it is shown that siderite only forms once the critical super-saturation is exceeded within a defined boundary layer and that the steel microstructure has critical role in developing a surface texture within which the critical super-saturation could develop. This idea of siderite nucleation in solution with a critically saturated boundary layer close to the metal surface is unlike the heterogeneous nucleation and growth phenomenon which occurs directly on the surface via solid state formation [1]. Establishment of this ideology was able to resolve the apparent thermodynamic anomaly observed in practice.
One of the apparent thermodynamic anomalies in CO2- H2S mixed system is couched on the fact that in spite of the higher (∼3 time) aqueous solubility of H2S compared to CO2 under similar temperature and pressure conditions, the formation of iron sulfide has been observed to be faster and predominant over iron carbonate under most parametric conditions even at a trace level of H2S concentration in CO2-H2S system. This fact indicates the formation of iron sulfide and iron carbonate films to be regulated by different mechanisms. In-situ synchrotron study revealed the early stage nucleation of iron carbonate (siderite) film and indicated that to be a gradual process giving rise to the formation of crystalline siderite phase only after the critical supersaturation stage is reached. Given that, there is significant time lag between the start of supersaturation and critical supersaturation limit, there is a possibility for iron sulfide formation during that time lag, as it forms by solid state formation mechanism which is a faster process. It is the in-situ synchrotron study which made it possible to illustrate the appreciable time lag between the start of supersaturation and critical supersaturation limit.
Ingham et al. [2] used in-situ synchrotron small- and wide-angle X-ray scattering (SAXS and WAXS) to demonstrate that the formation of crystalline siderite (FeCO3) during the corrosion of steel in CO2-saturated brine is actually preceded by the formation of a colloidal precipitate and an amorphous surface layer, both assumed to be amorphous ferrous carbonate. Grazing incidence SAXS showed that upon the application of an anodic potential, film forms instantaneously and then a separate population of particles develops in the later stage followed by the formation of the ultimate crystalline FeCO3, observed by WAXS. Ingham et al. [2] interpreted these observations in terms of crystal nucleation within the amorphous surface layer. This observation was speculated to bear a significant consequence on the morphology of the corrosion scale and hence its protectiveness. However, it would be important to understand the effects of local pH change as well as variation in temperature in this gradual formation and development of siderite scale and then to find out a quantitative correlation of this process with the mentioned parameters.
The fact of stable, adherent and protective siderite film formation in presence of trace amount Cr3+ was known [3, 4]. However the associated mechanism was not clearly understood until in-situ synchrotron x-ray diffraction study revealed a clearer picture of the mechanistic aspect of the expedited siderite film formation in presence of traces of Cr3+[2, 5]. This recently done in-situ synchrotron study made it clear that traces of Cr3+ in the solution significantly expedites the precipitation rate of the colloidal precursor and thus accelerate the appearance of the crystalline scale through its catalyzing influence on the nucleation process by modulating the local pH level at the steel surface and thus reducing of the critical supersaturation for precipitation.
Another interesting and critical factor in developing surface texture within which the critical supersaturation can be developed is steel microstructure. Consequently, steel microstructure must have intimate relationship with the corrosion process and morphology of the scale as microstructure can change the diffusion conditions at the steel surface affecting the local supersaturation of siderite. However, in-depth mechanistic information related microstructural effect on adherent and protective scale formation was hardly available in the literature. It is recommended to perform in-situ synchrotron X-ray diffraction experiment in order to make a detailed investigation of such a phenomena. Ko et al [6] recently conducted such a study in order to investigate the effect of microstructure and boundary layer conditions on CO2 corrosion of low alloy steels. This recent investigation clearly demonstrated that the nucleation of crystalline scales onto the surface of steels under CO2 corrosion at elevated temperature is critically dependent on the initial surface roughness, microstructure-related surface roughness developed during corrosion. This study also indicated the interdependence between microstructure and chromium-enhanced siderite nucleation. However, finding out the quantitative effects of surface roughness on the initial nucleation process (rate) of the scale as well as the stability of the scale would be a good addition to this study.
References:
[1] B. Ingham, M. Ko, G. Kear, P. Kappen, N. Laycock, J. A. Kimpton and D. E. Williams, “In-situ synchrotron X-ray diffraction study of surface scale formation during CO2 corrosion of carbon steel at temperatures up to 90°C”, Corrosion Science, 52 (2010), 3052–3061.
[2] Bridget Ingham, Monika Ko, Nick Laycock, Nigel M. Kirby, David E. Williams, “First stages of siderite crystallisation during CO2 corrosion of steel evaluated using in-situ synchrotron small- and wide- angle X-ray Scattering”, Faraday Discussion, 2015.
[3] M B Kermani, J C Gonzales, G L Turconi, D Emonds, G. Dicken, L Scoppio, “Development of Superior Corrodion Resistance 3% Steels for Downhole Applications”, NACE Annual Conference & Exposition, paper 3116, 2003.
[4] R M Garrels, C L Christ, “Solution, minerals, and equilibria”: San Francisco, California, Freeman, Cooper & Company, 1965, p 450.
[5] M Ko, B Ingham, N Laycock, D E Williams, “In-situ synchrotron X-ray diffraction study on the effect of chromium additions to the steel and solution on CO2 corrosion of pipeline steels”, Corrosion Science, Vol 80, 2014, pp 237–246.
[6] M. Ko, B. Ingham, N. Laycock, D.E. Williams, “In situ synchrotron X-ray diffraction study of the effect of microstructure and boundary layer conditions on CO2 corrosion of pipeline steels”, Corrosion Science, Vol 90, 2015, pp 192–201.
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Resource Allocation Under Footprint Constraints in Industrial Parks
Authors: Dhabia M Al-Mohannadi, Kholoud Abdulaziz, Sabla Y. Alnouri and Patrick LinkeWith growing climate change concerns, depleting natural resources and decrease in oil and gas prices, it is more vital than ever to efficiently manage natural resource allocation. Methane, the key component in natural gas and a raw material for numerous chemicals, is Qatar's more abundant resource. Natural gas can be monetized through many alternative paths. It can be sold as natural gas, either through pipelines or in liquefied form, or converted into diverse sets of fuels and materials using many alternative processing technologies. In the meantime, concerns of the effects of increased carbon dioxide concentration in the atmosphere, majority of which are emitted from large industrial stationary sources and fuel consumption, have caused the global society to seek ambitious emission reduction targets.
While on the one hand natural gas provides a clean fuel associated and enables carbon dioxide emissions through fuel switching globally, its local processing is associated with significant footprints. In the case of Qatar and its small population, this has resulted in very high per capita emissions. Most of the emissions are stationary and spatially concentrated in industrial clusters, where they originate mainly from natural gas processing, hydrocarbon processing, petrochemicals and metals production, and power and water generation.
The industrial sector is challenged to balance profit making activities from natural gas monetization with increasing pressures to reduce overall carbon dioxide emissions. Conventional design of industrial parks centering on natural gas are carried out in an ad-hoc process that depends on the expertise of designers, available capital, market demand and regulations. Reduction methods in the past have been limited in technology, energy integration or geographical proximity to apply carbon capture and sequestration (CCS).
Recently, carbon integration (Al-Mohannadi and Linke, 2015a,b) has been introduced as a systematic approach to determine the most efficient carbon dioxide reduction options in industrial parks by considering multiple carbon dioxide sources, potential carbon sinks, the layout of the city and the associated costs of transmission and conditioning. Carbon integration looks into the various conversion routes that take carbon dioxide into value added products, which can be converted chemically, biologically or through geographical utilization such as Enhanced Oil Recovery (EOR) applications. This creates incentives to reduce carbon emissions, to create synergies between firms and to produce additional products in the cluster, while adhering to required emission reduction targets.
Beyond focusing on low cost carbon dioxide emissions reduction, the broader design challenge for a natural gas monetizing industrial cluster is to identify the most promising configurations from the vast number of alternatives that exist from the possible combinations of many alternative natural gas monetization processes, and the many alternative carbon management options that could be applied, whilst exploiting synergies between natural gas conversion and carbon management. Most previous works have focused on different aspects of the overall problem: optimizing gas conversion processes, and managing carbon dioxide emissions reductions. Very few works have considered monetization in industrial clusters, and there is no published work on how to systemically make gas monetization decisions under carbon dioxide emissions constraints.
This work introduces the first systematic approach to allocate natural resource under carbon dioxide footprint constraints. The approach yields integrated natural gas and carbon dioxide management schemes that yield the maximum profit for the given gas monetization and carbon dioxide management options and constraints that exist in the industrial cluster. The work explores different carbon dioxide emission reduction scenarios; expansion plans and determines most profitable product mix from an industrial cluster. By taking into consideration the tradeoff between environmental performance and potential profitability of natural resource allocation, it provides valuable information to decision makers from an optimization based tool. Policy makers and regulators can use the tool for developing strategies and for planning of more sustainable industrial clusters, parks or cities.
The work is illustrated using a case study to demonstrate the application of the method on industrial cluster resembling a configuration of gas monetization options often observed in oil and gas centered economies.
Keywords
Resource Allocation, Climate Change, Carbon Dioxide emissions, Carbon Integration, Natural Gas Allocation, Gas Monetization, Carbon Reduction, Process Integration, Industrial Parks, Planning, Modeling, Optimization.
References
Al-Mohannadi, D.M., P. Linke (2015). On the Systematic Carbon Integration of Industrial Parks for Climate Footprint Reduction. Journal of Cleaner Production, DOI: 10.1016/j.jclepro.2015.05.094.
Al-Mohannadi, D.M., S.K. Bishnu, P. Linke, S.Y. Alnouri (2015b). Systematic Multi-Period Carbon Integration in an Industrial City. Chemical Engineering Transactions 45, 1219–1224.
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Improved Gas and Water Pollution Sensors Based on AlGaN/GaN HEMTs for Air and Water Treatment Systems
At the present time, serious threats are being posed to the environment due to pollutants in both the air (e.g. automotive exhaust emissions) and water (e.g. phosphates, nitrates, heavy metals). In an effort to improve these environmental hazards, automotive emissions standards and regulations on water pollutants are becoming more and more strict each year. One of the major limitations in meeting these regulations is the ability to quickly and accurately detect low concentrations of the target molecules.
We report the fabrication and experimental testing of a new generation of microsensor technology that can detect a wide range of gases in the air as well as pollutants in a liquid environment. These sensors are based on AlGaN/GaN high electron mobility transistors (HEMT) with functionalized gate contacts acting as the sensing layer. The use of high bandgap, group-III nitride semiconductor materials gives the sensors a high thermal and chemical stability, making them suitable for high temperature applications (above 600°C) and in harsh chemical conditions. Depending on the type and structure of functional layer, the adsorption of the target molecules leads to change the surface depletion layer which has a direct affect on the sensitivity and the selectivity of the device. Extensive modeling and design of the AlGaN/GaN HEMTs has been performed to optimize the devices for detection of exhaust gases and water pollutants. This includes the design of each of the material parameters (e.g. AlGaN thickness, Al incorporation) and the functionalized contacts (e.g. material, dimensions, morphology).
Experimental results using a Pt sensing layer show detection of 10–1000 ppm NO and NO2 gas with changes in current of 0.8 and 2.8 mA, respectively. Detection of NH3 gas in a range of 150 ppb–15 ppm was also demonstrated, and can be compared to detection limits of only 35 ppm for similar devices. This is the first time that detection of NO has been demonstrated using a HEMT sensor, and the first time selective detection of NO, NO2, and NH3 has been demonstrated using a single transistor device. Furthermore, the sensitivity to NO2 and NH3 were significantly higher in our optimized device compared to other HEMT sensors. Dynamic response times were shown to be between 1–3 seconds for each gas, showing that these sensors can perform in real-time applications.
In addition to exhaust gas detection, an open-gate HEMT sensor was designed and fabricated as a water pollution sensor and showed detection of both phosphates and nitrates in water. This is the first time that phosphates have been detected using a HEMT sensor, and shows that HEMT sensors can be useful in the prevention of eutrophication of fresh water bodies. We are currently exploring HEMT sensor designs for the detection other water pollutants such as heavy metals, inorganic and organic molecules that damage or contaminate water supplies.
The experimental results presented in this abstract demonstrate that the functionalized AlGaN/GaN HEMT sensors we have developed are promising for real-time air and water treatment applications due to their low detection limits, high sensitivities, fast response times, and selectivity by functionalizing the sensing layer for specific target molecules. Therefore, this technology has the potential to drastically improve the reduction of pollution in the air caused by automotive exhaust and other gases, as well as pollution in lakes and other viable sources of water.
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Facile Synthesized Mo 2 C Electrocatalyst Supported on Mesoporous Carbon for Hydrogen Generations
More LessThe surge in the field of renewable energy aiming to develop clean energy technology is continuing to rise. Quest for a H2-based economy derived from non-fossil resources remains at the forefront of future fuels. During the past few decades there has been intense research on the utilization of electrical energy to produce H2 in an energy efficient and environmentally benign way. Electrocatalytic hydrogen generation via water electrolysis provides an important alternative to that extracted from hydrocarbon resources. One of the most crucial components which could revolutionize H2 production is that the design and development of a novel electrocatalyst that can efficiently split water to generate H2. Currently, platinum (Pt) is known as the state-of-the art electrocatalyst for hydrogen evolution reaction (HER). However, due to cost and scarcity of Pt, research focus shifted to precious-metal-free based materials for efficient HER reaction. As results, a wide variety of transition-metal-based electrocatalysts have been developed and investigated. To this end and due to unique d-band electronic structure, Mo-based electrocatalyst such as, Mo2C and MoS2 has been the subject of intense investigation for HER reaction. Yet, functional and robust catalysts operating with reasonable current densities (J) at low overpotential in brine water are still scarce.
Herein, we demonstrate a facile synthesis of β-Mo2C embedded on mesoporous carbon support; Metal Organic Framework (MIL 53(Al)) was utilized as a novel source for mesoporous carbon support. Microscopic studies revealed the formation of monodisperse Mo2C with
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Microbial Desalination Cell: An Integrated Approach for Wastewater Treatment and Desalination Systems for Sustainable Water Desalination and Wastewater Treatment
Authors: Suraj Sevda, Ibrahim M Abu Reesh and Zhen HeThe availability of drinking water from the current available sources is decreasing due to the high demand and population increase. Seawater is a potential source for drinking water but the current desalination technology is energy intensive, therefore energy efficient desalination technology is desired. In the past decade microbial fuel cells (MFC) were emerged for simultaneous wastewater treatment and bioelectricity generation, in the anodic chamber of MFCs, microbes work as a biocatalyst to generate electrons from the oxidation of the organic compounds (wastewater) and transfer them to the anode electrode. These electrons flow through an external circuit to the cathode electrode where they used to reduce terminal electron acceptors (e.g., oxygen). Microbial desalination cells (MDC) are new potential technique for seawater desalination, in this device energy from wastewater is extracted by using microbes and without any external energy source, water desalination is driven. To convert an MFC to an MDC, a middle chamber is inserted in between the anodic and cathodic chambers of MFC using a pair of anion and cation exchange membranes. This middle chamber works as a desalination chamber in the MDC (Fig. 1). The cations and anions from the desalination chamber moved to the anodic and the cathodic chambers, respectively, due to the cell potential difference between the anode electrode and the cathode electrode; as a result, salts are removed from the saltwater.
The first MDC study was reported in 2009 and since then there have been nearly 74 papers published about various aspects of MDC design and development, indicating a strong interest and rapid development of this technology. During this short period of time, various MDC designs were developed for salt removal and wastewater treatment. The desalination chamber volumes were increased from 3 ml to 105 liters and further progress is going on for salt removal and at the same time wastewater treatment. The performance of MDC was investigated using various concentrations of saline water in desalination chamber using industrial or synthetic wastewater in the anodic chamber. Different MDC designs were reviewed here. These developed new MDC designs named as air cathode MDC, stacked MDC (SMDC), up flow MDC (UMDC), recirculated MDC (RMDC), microbial electrodialysis cell (MEDC), submerged microbial desalination- denitrification cell (SMDDC), microbial capacitive desalination cell (MCDC) and osmotic microbial desalination cell (OsMDC). Different anion and cation exchange membranes were compared for power generation and desalination efficiency. This paper also reviews different substrates that have been used in MDCs so far. The MDCs provide an energy self-sustainable system in that water desalination and wastewater treatment conducted by using microbes as catalyst in the anodic chamber. Still the available MDCs were very small in volume that can't meet today's water desalination needs. In the long term operation of MDC, the membrane fouling and electrode stability are still two major problems limiting the development of MDCs. The possibility of scale-up, possible future potentials for synchrony of the MDCs with current desalination techniques were also discussed. Case study with real wastewater in the anodic chamber and real seawater in the desalination chamber were also discussed.
Acknowledgements
This work was made possible by NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.
Reference
Sevda, S., Yuan, H., He, Z., Abu-Reesh, I.M., 2015. Microbial desalination cells as a versatile technology: Functions, optimization and prospective. Desalination 371, 9–17. doi:10.1016/j.desal.2015.05.021
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Toxicity of Chlorine to Five Marine Species from Various Trophic Levels of Qatari Waters
Authors: Suhur Saeed, Nandita Deb, Sarah Bacha and Christopher WarrenBackground
Chlorine is extensively used as a powerful oxidizing agent in the countries surrounding the Arabian Gulf for water treatments and biofouling control. The usage has been increasing significantly as demand for water grows considerably both in industry and domestic use. This is due to the fact that it is a well-tested technology, has had a history of long-term worldwide industrial use and is of acceptable cost. Sodium hypochlorite (NaOCl, commonly termed chlorine) is a common form of chlorine that is used and in all cases it is produced on site by means of an electro-chlorination plant (ECP). In seawater, chlorine produces a mixture of hypochlorous acid (HOCl) and hypochlorite ion (OCl − ). These rapidly react with the bromide ion to form a mixture of hypobromous acid (HOBr) and hypobromite ion (OBr − ). The acute oxidants formed by chlorination are therefore short lived and are not persistent in seawater, but can be quite toxic. Further complicating the environmental concern of chlorination is the production of numerous, and more persistent, compounds formed by complex reactions between chlorine/bromine and the organic constituents of seawater, collectively described as chlorination by-products (CBPs). Many CBPs are persistent and may be toxic to marine organisms subjected to long-term exposures. The Gulf waters support a range of coastal and marine habitats including mangrove swamps, seagrass beds and coral reefs. However, marine organisms in the Arabian Gulf are living close to their tolerance limits due to the extreme environmental stressors of temperature and salinity. Anthropogenic stressors such as chlorine may further exacerbate these natural stressors.
Objectives
In order to evaluate the risks of chlorine exposure to Arabian Gulf marine organisms, the aims of this study were to 1) develop protocols for acute and chronic toxicity tests involving native species at different trophic levels, 2) correlate sensitivity to other marine organisms used as indicator species in risk assessments, 3) draw conclusion from the results and explore ways that this could be used for informing environmental management activities.
Methodology
Materials and methods
Stock solution of calcium hypochlorite was prepared in filtered artificial seawater (0.45 μm filter paper) daily in dark bottles. Concentration of chlorine in the experimental chambers were verified daily by the N,N-diethyl-p-phenlenediamine (DPD) colorimetric method. Different concentrations of chlorine were either administered as a continuous flow through or via daily renewal.
Exposure to test species
Species were collected from different location around the coastal areas of Qatar. They were then cultured in the laboratory using conditions of the Arabian Gulf. Species used in the tests include phytoplankton (Synechococcus sp.), zooplankton (Uterpina acutifrons), pearl oysters (Pinctada radiata), sea urchins (Diadema setosum) and killifish embryos (Aphanius dispar).
Results
Sensitivity varied across the trophic levels for each species and was found to be in line with other test organisms that are used in established toxicity procedures. All five species used were found to be useful for certain types of toxicity testing. For example, Pinctada radiata and Diadema setosum were excellent in testing for successful fertilization and early development stages, while local Aphanius dispar embryos were useful for following sub-lethal effects such as malformation and hatchability. Embryos of oysters and urchins were found to be the most sensitive to chlorine (Fig. 1.). Effect of chlorine was only observed near or after hatching has occurred. Continuous exposure showed more effective than the semi-renewal method.
Discussion and conclusion
While chlorine continues to be used heavily globally, available toxicology data are either very limited or out dated especially those based on the Arabian Gulf. The purpose of this study was to increase the knowledge of chlorine chemistry and toxicity especially the sensitivity towards the Arabian Gulf species. Results obtained reveal that the sensitivities of all five species used in this study are in line with species used internationally in similar tests. LC50s were determined for all species and are currently being used in modelling tools to determine the fate and environmental risks of chlorine. Chlorine being a powerful oxidizing agent asserted its effect immediately after contact. It loses its potency within the first hour in seawater and this may contribute to the low effect shown in this study compared those in fresh water. Given the short-lived nature of chlorine as an oxidant in seawater, our attention has also been focused on the sub-lethal effects that may be attributed from the by-products. Work is ongoing in this area. Expanding tests with species used in this study to evaluate their sensitivity towards chlorine by-products will further increase our understanding of their chemistry and environmental risk in the Arabian Gulf and will provide a science-based tools for making management decisions.
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Lubrication in Desert Environments: Oil-Soluble Organo-Silver Molecules Designed for In-Situ Deposition of Metallic Silver at High Temperatures
The quest for improved engine performance and reduced emissions drives the design of increasingly sophisticated lubrication technologies. Lubricating oils and greases are engineered to function over a broad range of temperatures and loading conditions. Modern engines operate at higher temperatures, speeds and pressures than previous engines, and therefore require lubricants capable of handling harsher conditions. Reliable performance in extreme conditions is also necessary in emergency and combat situations. Thus, a major challenge for next-generation lubrication technology is to improve performance at extreme temperatures exceeding the thermal degradation limits of conventional engine oils.
In automotive engines, the surface temperature of critical tribological components can easily reach 200°C, while asperity contacts can generate ‘flash temperatures’ up to 1000°C. These extreme pressures and temperatures in the contact zones can lead to plastic deformation, wear away mating surfaces, and catalyze chemical reactions which damage the surfaces and lubricant. Tests carried out on PAO4 and 15W40 motor oils show that they decompose at 275°C, irreversibly losing viscosity and generating oil-insoluble acids and salts that corrode surfaces and form sludges.
Surface coatings, such as diamond-like carbon, and texturing can be used to reduce friction at temperatures which lead to motor oil thermal degradation. However, such treatments are costly for large components, and these coatings cannot be replenished without dismantling the treated machinery. Soft metal ductility can also be utilized in lubrication. The low shear-strengths of metallic films can form smooth “glaze layers” on tribosurfaces which lubricate sliding contact. Noble metals have oxidative stability, enabling lubricious performance at extreme temperatures. Silver-coated contact surfaces exhibit reduced friction and wear from 25–750°C. However, a method is required to dissolve metallic silver precursors in base oil for deposition at high temperatures.
Silver nanoparticles are known to increase surface fatigue life, decrease friction, and wear, and work synergistically with other lubricant additives. However, silver nanoparticles are expensive, difficult to suspend in nonpolar media, and typically require a surfactant to prevent agglomeration. An alternative, described here, is to use a silver-containing molecular precursor. Organic ligands impart solubility to silver atoms and control the organosilver complex decomposition temperature to deposit silver only when and where it is needed. Controlled silver deposition is arguably more economical than full protective coatings. Also, a lubricant additive can be replenished during oil changes to provide more lubricious silver to high asperity engine contact regions. We report here the synthesis, characterization, and tribological implementation of a silver-pyrazole complex, silver 3,5-dimethyl-4-n-hexyl-pyrazolate (HPzAg)3. This complex is oil-soluble and undergoes clean thermolysis at ∼310°C to deposit lubricious, protective metallic silver on mechanical surfaces. Temperature controlled tribometer tests show that an optimized 2.5 wt% (HPzAg)3 loading reduces wear by 60% in PAO4 (poly-α-olefin lubricant) and 70% in a commercial fully-formulated motor oil (military grade 15W40). This organosilver complex also imparts sufficient friction reduction that the tribological transition from oil as the primary lubricant through its thermal degradation, to (HPzAg)3 as the primary lubricant, is experimentally undetectable.
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Research in Irrigation Canal Lining: An Experience from Sudan
Authors: Tarig El Gamri Ibrahim and Amir Bakheit SaeedThe amount of water below 1000 m3 per capita per annum is considered as the water poverty zone. With business as usual scenario it is estimated that by the year 2025 half the world's people will live in countries with high water stress. Based on Global averages irrigation water demands accounts for about 70% of all water uses. Meanwhile water use efficiencies of irrigated projects are generally very low particularly those under traditional surface methods. On the other hand conveyance losses vary within a range of 25–50% of the total diversion. Generally canal lining can save about 75% of the conveyance losses. However, high quality linings were found to practically eliminate such losses. The paper reviews the benefits of canal lining, which include hydraulic, economic and environmental benefits. Since seepage from irrigation canals is the most important factor in lining considerations the paper presents some review on the phenomenon. Canal lining is usually classified into four main types: hard surface linings, membrane linings, earth linings and soil sealants. The paper critically discusses the different types and highlights the criteria for selecting the appropriate lining technique. The paper also reviews the recent technical developments and research at the global level in this field; these include the development of new materials and techniques. Finally the paper presents a review of the canal lining related research executed by the National Centre for Research, Sudan during the last 20 years. These include development of low cost lining (building) materials using locally available aggregates (sand and gravel), lining irrigation canals on expansive soils and development of low cost concrete pipes and production of precast canal-lets. Canal lining was found conserve irrigation water, reduce fuel consumption, reduce irrigation time and reduce labour requirements. Development of Low Cost Building Materials for Canal Lining:: Four low cost building materials have been studied, these are namely khafgi, ferrocement, kenaf sheets and concrete made of small-sized gravel available near RDRC. Kenaf sheets were rejected because of the low durability expected. The other three materials were found to be feasible based on strength, permeability and durability. Water transported sand near RRS was found to be suitable for building works including lining whereas wind transported sand can hardly be recommended for such works.
Hand placement cast in-situ was adopted using the semicircular configuration, as besides improving structural integrity of the canal, it is the most hydraulically efficient section particularly for small canals. A semi circular cast-in situ form was made to construct channel sections that accommodate maximum discharges at RDRC. The work is done in alternate sections and the lap-joint technique was used. Pipe Casting:: It have been noticed that some desert farms the canalization system is liable to be buried by wind-blown sand. To avoid this problem the system should adopt pipes instead of open channels; however, traditional farmers cannot afford to cover such expenses since such pipes are relatively expensive in the local market. To overcome such problems the study was extended to develop intermediate technologies for pipe casting. A form was designed and constructed in a local workshop. The form is made of PVC pipe equipped with a handle as an internal unit the external unit is made of sheet metal also a wooden base is used. The external unit is composed of two semi-cylinders; a steel channel is welded to each end of each semi-cylinder to facilitate fastening meanwhile a rubber strip used to prevent water leakage. Again locally available aggregates were used. Laboratory tests (Impact Value and Crushing Value) showed that locally available gravel is suitable for pipe casting. The internal unit of the form is removed about an hour after the end of the casting process and the external one after a day. The pipes were then cured for 7 days. Compressive Strength and permeability tests proved that the produced pipes comply with the Known International Standards. Additionally the pipes were tested in the field by passing a tractor, which represent the maximum expected load in such farms without being damaged. Lining Irrigation Canals on Expansive Soils:: Um Jawaseer Desert Farm Project, which is located in Wadi El Magadam, the Northern State was established in the year 1989 for the settlement of the nomads of El Hawaweer Tribe. The project harnesses water from an aquifer of about 40 m below ground surface for irrigation and other purposes. Evaluation studies showed that the project is successful in creating better livelihood for the people of the area.
Huge water losses were encountered in the first two phases. In the third phase the project adopted stone lining, which is estimated to conserve about 1/3 of the irrigation water. However, stone lining is known to be one of the least effective lining techniques. Identification tests were carried out in accordance with the British Standards and showed that Um Jawaseer soil possesses swelling properties.
To reduce (mitigate) the expansive potential of Um Jawaseer soil some additives (cement, lime, bituminous emulsion and refuse oil) were tested, these additives were added to the soil at a rate of 6% by weight as recommended by some authors.
To avoid damage the linings a combination of soil treatment and construction technique was used for the lining of Um Jawaseer irrigation system. The soil was first excavated to a depth of 60 cm and mixed with the additive (cement). Water is added to the soil/ cement mixture till the optimum moisture content (plastic limit) was reached. Finally the mixture was compacted into two layers (30 cm each). As for the construction technique the semi-circular channel cross section was used since it produces integrity in structure and the channels so constructed can resist external forces. This combination gave very encouraging results since it is found to mitigate upheaval damage and produce strong and efficient conduits. Precast concrete canal-lets:: The merits of precasting are attributed to the high quality control coupled with the technique. Precasting was advised by some authors for mass production of tertiary canals. The J- Section was selected for ease of casting the form is made of metal sheets.
The form was filled of concrete, while being compacted with steel rod, left for an hour to allow for setting of concrete and then released. The finished section is allowed to dry for 24 hours and then cured for 7 days by wetted kenaf sacks. Keyword: Seepage, Irrigation, Canal lining, Pre-casting, efficiency
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Solar Thermochemical CO 2 Utilization via Ceria Based Redox Cycle
According to the recent studies, it is expected that the global energy requirement will increase from 14 TW to 30 TW by the year 2050. Currently, fossil fuels are the major energy source utilized for the fulfillment of the energy requirement. Due to the excessive utilization of fossil fuels, the concentration of greenhouse gases in the atmosphere is increasing day by day and hence there is a pressing need to develop technologies to produce carbon free renewable fuels. The liberated CO2 can be re-energized into CO via ferrite based thermochemical looping process using concentrated solar energy. The CO produced via solar thermochemical CO2-splitting can be combined with H2 derived from ferrite based solar thermochemical water-splitting process to produce solar syngas which can be further processed to liquid fuels such as Methanol, Diesel, and Kerosene via the Fischer-Tropsch process. The current research trends in solar thermochemical community are focused towards high and constant levels of solar fuel production in multiple cycles and it is believed that non-volatile mixed metal oxides such as undoped and doped ceria will significantly improve the production of solar fuels. Ceria based redox cycle comprises of two steps. First step belongs to solar endothermic reduction of ceria at higher temperatures releasing O2. The second step corresponds to the non-solar exothermic re-oxidation of the reduced ceria at lower temperatures by H2O, CO2, or a mixture of the two producing H2, CO or syngas.
In this investigation, Zr and Hf doped ceria based redox nanoparticles (various doping combinations) were synthesized using a co-precipitation method. The respective metal precursors were dissolved in water. Upon complete dissolution, excess ammonium hydroxide (NH4OH) was added drop-wise to the mixture under vigorous stirring to precipitate the mixed-metal hydroxides (final pH = ∼9). The obtained precipitates were filtered, washed with water until free from anion impurities and oven dried at 100 °C for 8–10 h. Subsequently calcination was performed at different temperatures in air. The calcined powders were characterized by powder X-ray diffraction, BET surface area analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The compositional purity of the derived Zr/Hf doped ceria was identified using powder XRD and the obtained results indicate phase pure composition of the derived materials (based on the stoichiometry selected during synthesis). The derived Zr/Hf doped ceria also possess high specific surface area (SSA) and porosity which is confirmed by BET analysis. The SEM and TEM analysis indicate formation of Zr/Hf doped ceria nanoparticles in the range of 10 to 50 nm. Synthesized Zr/Hf doped ceria nanoparticles were further tested for thermochemical CO2-splitting by using a high-temperature thermogravimetric analyzer (TGA). Multiple thermal reduction and oxidation (by CO2) cycles were performed at various operating conditions by using TGA while the O2 and CO was quantified by gas chromatography. Results obtained indicate that the derived Zr/Hf doped ceria is capable of producing higher amounts of solar CO as compared to previously investigated undoped and doped ceria materials. Also, the Zr/Hf doped ceria was examined in 20 thermochemical cycles towards successive thermal reduction and CO2 splitting reactions and the obtained findings indicate stable redox reactivity and thermal stability.
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Reactive Absorption of CO 2 Using Ethylaminoethanol Promoted Aqueous Potassium Carbonate Solvent
Atmospheric concentration of CO2, which is considered as one of the major greenhouse gases (GHGs), has increased up to 398 ppmv as of 2015. CO2 concentration in atmosphere was 280 ppmv in pre-industrial era, and due to the continuous discharge, it is expected to increase up to 550 ppmv by 2050. Many of the major industrial sources of CO2 emissions are natural gas fired power plants, synthesis gas used in integrated gasification combined cycle (IGCC) and power generation, gas streams produced after combustion of fossil fuels or other carbonaceous materials, and oxyfuels. Reactive absorption of CO2 from the industrial off gases by using chemical solvents is considered as one of the most common, efficient, and cost effective technologies utilized by the industry for CO2 capture. The captured CO2 can be stored by using the geological or oceanic sequestration approaches. As an alternative to geological or oceanic sequestration, the captured CO2 can be re-energized into CO by using solar energy and combined with H2, which can be generated from different methods, to produce syngas. The syngas produced can be further processed to liquid fuels such as methanol, gasoline, jet fuel, etc. via the catalytic Fischer-Tropsch process.
In past, a variety of chemical solvents (mostly aqueous amines and there derivatives) have been used for CO2 capture from different gaseous streams via reactive absorption. Though the amines are attractive for the CO2 capture application, there are several disadvantages such as very strong corrosion to equipment and piping, high energy requirement during the stripping of CO2 and they are prone to oxidative and thermal degradation. Recently, use of aqueous potassium carbonate (K2CO3) as a solvent for the absorption of CO2 has gained widespread attention. The usage of K2CO3 has been employed in a number on industries for the removal of CO2 and H2S. Due to its high chemical solubility of CO2, low toxicity and solvent loss, no thermal and oxidative degradation, low heat of absorption, and absence of formation of heat stable salts, K2CO3 seems to be more attractive compared to the conventional amines towards CO2 capture. However, K2CO3 solvent shows slow rate of reaction with CO2 and, consequently, low mass transfer in the liquid phase as compared to the amine solvents. Hence, several investigators are focused towards improving the rate of reaction of CO2 in K2CO3 solvent with the help of different types of promoters.
In this paper, the kinetics of absorption of CO2 into an aqueous K2CO3 (20 wt %) promoted by ethylaminoethanol (EAE) solution (hereafter termed as APCE solvent) was studied in a glass stirred cell reactor using a fall in pressure method. Reactive absorption of CO2 in EAE promoted aqueous K2CO3 solution (APCE solvent) was studied at different initial EAE concentrations (0.6 to 2 kmol/m3) and reaction temperatures (303 to 318 K). The reaction between the CO2 and APCE solvent was very well represented by the zwitterion mechanism. The N2O analogy was employed for the determination of H_(CO2) in the APCE solvent. The H_(CO2) was observed to be decreased by 5 and 31% due to the increase in the EAE concentration from 0.6 to 2 kmol/m3 and reaction temperature from 303 to 318 K, respectively. The D_(CO2) in the APCE solvent was also decreased by 21% due to the similar increase in the initial EAE concentration. In contrast, the D_(CO2) increased with the rise in the reaction temperature from 303 to 318 K by a factor of 1.678. The rate of absorption of CO2 in the APCE solvent was observed to increase by 35.10% and 47.59% due to the increase in EAE concentration (0.6 to 2 kmol/m3) and reaction temperature (303 to 318 K). The absorption kinetics was observed to be of overall second order i.e. first order with respect to both CO2 and EAE concentrations, respectively. The rate constant (k_2) for the absorption of CO2 in the APCE solvent was observed to be equal to 45540 m3/kmol√s at 318 K. The temperature dependency of k_2 for the CO2 – APCE solvent system was experimentally determined as: k_2 = (1.214 × [10]^18)√exp(( − 9822.7)/T). Findings of this study indicate EAE as a promising promoter for the aqueous K2CO3 solution.
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Mid-Infrared Dual Frequency Comb Spectroscopy for Time-Resolved Methane Detection
We performed dual frequency comb spectroscopy for time-resolved methane detection in real time, which is of demanding interest for the natural gas industry, environmental science, atmospheric monitoring and geoscience research. Broadband MIR frequency combs provide high brightness and frequency precision for many spectroscopic applications. To increase the detection sensitivity, a multipass cell or a high finesse cavity with mid-infrared frequency comb produced by difference frequency generation is used. This setup increases also the interaction length between the detection target molecules and the MIR frequency combs. Both frequency comb sources are based on femtosecond Er-doped fiber laser oscillators with stabilized repetition rates at ∼250 MHz, which is stabilized and locked to sophisticated frequency references or GPS system in order to achieve comb-teeth resolved spectral measurements. We implemented the mid-infrared dual frequency comb spectroscopy in the spectral range between 2900 cm− 1 and 3150 cm− 1 with 0.07 cm− 1 resolution with a novel multipass cell of ∼580 m interaction length to detect the trace amount of methane in ambient air. We determined the methane concentration in the ambient air of the laboratory to be ∼ (1.5 ± 0.1) ppmv. The minimum detection limit for the current setup is ∼60 ppbv with an 80 ms data acquisition time.
We note that most of current existing frequency comb technologies have relatively narrow bandwidth and microwatt power levels limited by the applications for sensitive and real time multi-target gas detection. Another approach based on OPO (optical parametric oscillator) sources provided hundred milliwatt power and broad spectra, but the repetition rates or the carrier-envelope offset frequencies were not fully controlled, which led to distorted spectral measurements. We resolved this problem by applying dual frequency comb lasers DFCS to use the later as Vernier scale for correcting the distortion of the first laser comb system. A simplified diagram of the experimental setup is presented in Fig.1.
In Fig. 1, the experimental setup includes two MIR comb sources, mirrors and lenses allowing to couple the MIR comb2 into the multipass cell, one 50:50 beam splitter (BS) to obtain the reference and signal pulses, one 92:8 beam splitter to combine pulses from two comb sources, and an MCT photodetector with electronics for data acquisition. The spectra measured with a scanning monochromator are shown in inset (a) for MIR comb1 (cyan) and MIR comb2 (red). Interferometric autocorrelation traces are shown in inset (b) for MIR comb1 (cyan) and (c) for MIR comb 2 (red). The absorption features in the spectra are due to water vapor in the laboratory environment. Spot patterns on the mirrors of the multipass cell with the visible red laser are shown in inset (d) and are produced when the alignment red laser is introduced with the flip mirror off. The entrance/exit hole of 5 mm diameter can be seen in the top left part of the right side mirror.
Our system is referenced to a Rb frequency standard (Stanford Research, PSR10). One advantage of these DFG sources is the passive carrier-envelope offset (CEO) frequency stabilization. Since the pump and signal fields originate from the same source, the generated idler field is carrier-envelope phase slip free. The MIR comb1 has ∼120 mW output power, covering a spectral range from 2.8 to 3.6 μm (2700 cm− 1 to 3600 cm− 1). The pulse duration is ∼80 fs. The MIR comb2, employing a higher power Ytterbium doped fiber amplifier, generates an MIR comb of ∼300 mW with a similar spectrum and pulse duration.
We lock two femtosecond DFG MIR combs with slightly different repetition rates at fr1 = 249,998,633 Hz and fr2 = 250,000,122 Hz, thus the difference is δfr = 1489 Hz. In the time domain, when a pulse pair from two sources overlaps in time, the center burst of an interferogram is formed. Subsequent pulse pairs impinge on the detector with linearly increasing time delay. As a result, the detector records an interferogram formed by many pulse pairs of various delays. Because pulse pairs repeatedly move through each other, a new interferogram starts to form as soon as the previous is completed in 1/δfr∼0.672 ms. We record the interferogram train with an oscilloscope (Tektronix, MDO4104B-3) at a sampling rate of 250 MSPS with ∼10 bit resolution. The maximum record length is 20 Mega points, corresponding to 80 ms, or ∼118 complete interferograms. We first block the reference pulses, and record only signal interferogram train; which can be fast Fourier transformed to comb-teeth resolved spectrum with a simple software phase correction. The magnitude and phase radio frequency (RF) spectra are presented in Fig. 2.
In figure2, fourier transformed magnitude (black) and phase (green) RF spectra from an 80 ms signal interferogram train with a software phase correction: (a) broad range from 18 to 63 MHz, (b) zoomed-in narrow range from 40.25 MHz to 40.45 MHz. The phase is only perceptible and plotted at comb teeth positions since the RF signals between comb teeth are simply noise and therefore have a random phase between − π < /AσΣETHιγηλιγητ> to π. Because of the broad absorption features, the absorption dips can be observed in (a). The discrete comb lines with a spacing of δfr = 1489 Hz can be observed in (b).
Because of the passive CEO frequency stabilization, the DFG MIR frequency combs have a simple form of vm = mfr, where v is the optical frequency in MIR, m is an integer, and fr is the source repetition rate. For the measurements in the frequency domain, the individual comb lines from two sources beat between (N+2)fr1 and Nfr2, where N is an integer between ∼347,600 and ∼377,600, and down convert the optical frequency information at about 87∼95 THz to RF at about 18∼63 MHz with a simple formula Nfr2 − (N+2)fr1 = fRF. Thus, the optical up conversion follows fRFfr2/δfr+2fr1fr2/δfr. The measured complex spectrum of the signal is S(ν) = S0(v)exp[ − α(v)L/2 − iφ(v)], where S0(v) is the complex spectrum of the reference, α(v) is the molecular absorption coefficient, L is the path length of the multipass cell, φ(v) is the phase shift. We evaluate the DFCS quality factor, which is the product of the SNR and the number of resolved spectral elements normalized by the square root of the total acquisition time. With a SNR ∼100, in 80 ms acquisition time, we obtain the number of resolved spectral elements as 250 cm− 1/0.07 cm− 1 ∼ < /AσΣETHιγηλιγητ>3600, and the experimental quality factor is ∼1.3 × 106 Hz1/2.
This work was funded by the Robert A. Welch Foundation, Grant No. A1546 and the Qatar Foundation under Grant No. NPRP 6-465-1-091.
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Electrochemical Analyses of Sodium based Mixed Pyrophosphate Cathodes for Rechargeable Sodium Ion Batteries
Authors: Arsalan Ahmad Raja, Rana Abdul Shakoor and Ramazan KahramanLithium ion batteries (LIB) are widely applied to energy storage systems, like electric vehicles, ships. While limited reserves of lithium and cost of lithium enforced to explore new materials. Hence, Low cost and abundance of sodium has made Sodium ion batteries (SIBs) an attractive alternative for energy storage. Li ion replacement with Na ion will not require change of design in present LIBs, except change of cathode material (based on Na) and respective electrolyte. But the challenge exists to develop sodium cathode with good electrochemical performance and excellent thermal stability. Therefore, various crystal structure for sodium cathode material were explored to meet these challenges. Among cathode materials, pyrophosphate family represented high theoretical capacity due to existence of two sodium ions in a repeating unit. In this report we synthesized mixed pyrophosphate cathode, Na2Fe1/2Mn1/2P2O7, via simple solid state process. The precursors, Na2CO3 (Aldrich), (NH4)2HPO4 (Aldrich), FeC2O4.2H2O (Aldrich) and MnC2O4.2H2O (Aldrich), were mixed in stoichiometric ratio and extensively grinded in mortar and pestle. The fine powder was subjected to heat treatment under inert atmosphere at 350 °C, cooled, grinded and then annealed in inert atmosphere at 600 °C for 6 hours. The compositional and structural analyses confirmed the formation of a crystalline pure phase. The optimization of operation temperature, time and atmosphere (inert); and the formation of mixed component systems (i.e., incorporation of more than one transition metal) not only lead to single phase mode but also tune the voltage potential for high energy density. The X-ray diffraction (XRD) data of as-synthesized Na2Fe1/2Mn1/2P2O7 was indexed to a triclinic structure. This triclinic structure has open framework which facilitated diffusion of Na-ions during charging and discharging. Thermogravimetric Analysis (TGA) showed negligible weight loss (∼5%) when heated to 550 °C, indicating decent thermal stability of the material and differential thermal Analyses (DTA) hardly observed any endothermic or exothermic peak. Carbon coating of Na2Fe1/2Mn1/2P2O7 was proceeded to impregnate electrical conductance in the material. SEM images showed the difference between pristine Na2Fe1/2Mn1/2P2O7 and carbon coated Na2Fe1/2Mn1/2P2O7. The carbon coated Na2Fe1/2Mn1/2P2O7 was, then, casted on aluminum to prepare cathode. The casted material (cathode) was dried at 70 °C under vacuum for two hours. The materials was then assembled into coin cell as a cathode in the glove box. The electrochemical measurements confirmed that Na2Fe1/2Mn1/2P2O7 is electrochemically active at room temperature. It showed a single-phase reaction during cycling. This single phase reaction is changed by the Na environment through a change in Na/Vacancy ordering. The Na2Fe0.5Mn0.5P2O7 cathode represented discharge capacity of 80 mAh/g at C/20 in the voltage range of 2.0 to 4.5 V. The average redox potential was observed to be approximately 3.2 V (vs. Na/Na+). The capacity retention of Na2Fe0.5Mn0.5P2O7 is 84% over 90 cycles. Between first charge capacity and second charge capacity, Na2Fe0.5Mn0.5P2O7 cathode showed a difference of 5mAh/g only. This employs that sodium based mixed iron-manganese pyrophosphate (Na2Fe0.5Mn0.5P2O7) cathode has increased occupancy. The rate capability of Na2Fe0.5Mn0.5P2O7 shows 70% retention from 0.05 C to 0.5 C. Synthesis of Na2Fe1/2Mn1/2P2O7 in nanometric size may result in further improvement in its electrochemical performance.
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An Investigation into Hydrophobic Membrane Fouling in Desalination Using Membrane Distillation Technology
More LessDemand for freshwater supplies is continuously increasing globally to the extent where some parts of the world became highly water stressed. In particular, the Arabian Gulf states rely heavily on seawater desalination for their freshwater supply which is met using commercial seawater desalination technologies like thermal and reverse osmosis (RO) desalination processes. However, these technologies require considerable power input and actually do have a negative impact on the environment in terms of carbon footprint.
An alternative technology to the conventional desalination processes with potentially lower environmental impacts is the Membrane Distillation (MD) process. Membrane Distillation is a thermally-driven process that utilizes a hydrophobic micro-porous membrane and can utilize low grade heat and solar energy. The driving force of the process is the vapor pressure difference between the sides of the membrane that is induced by the temperature difference between the feed and distillate. However, one of the challenges facing the deployment of MD in large commercial scale desalination of seawater is membrane fouling.
The objective of this study is to investigate and compare the fouling characteristics of three different commercial membranes (PP membrane of 0.22 μm, PP membrane of 0.45 μm, and PTFE membrane of 0.22 μm) using two feed solutions (seawater from the Arabian Gulf and synthetic 100,000 ppm NaCl solution) using a bench-scale direct contact membrane distillation (DCMD) flat sheet module at hot water inlet temperature of 75 °C, cold water inlet temperature of 20 °C, and hot and cold water flow rate of 1.5 L/min. The study was performed by evaluating the distillate flux performance of the various membranes, measuring their contact angle before and after fouling, testing the quality of the distillate produced and examining the salt rejection, and interpreting membrane surface analysis using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) in order to study the morphology and the composition of the fouling layer.
Initially, the average flux obtained was 50.5 L/m2h, 50.3 L/m2h, and 38.3 L/m2h for PP membrane of 0.22 μm, PP membrane of 0.45 μm, and PTFE membrane of 0.22 μm, respectively. Therefore, PP membrane generated a higher flux than PTFE membrane. In terms of membrane pore size, the results showed that a larger pore size membrane is more prone to fouling and flux decay. In terms of membrane material, PP membrane showed a more rapid flux decline than PTFE membrane. Moreover, the percentage of drop in the average flux was more than 60%, 97%, and 94% for PP membrane of 0.22 μm, PP membrane of 0.45 μm, and PTFE membrane of 0.22 μm, respectively, after almost 19 h, 30 h, and 25 h of operation, respectively.
In terms of feed solution, a lower flux was obtained with the higher salinity feed, the 100,000 ppm NaCl solution. However, the difference was not very large, indicating that initially salinity does not have a great impact on the distillate flux.
The results also showed that fouling/scaling causes the quality of the distillates to deteriorate and that membrane wetting has occurred. A salt rejection of more than 99.9% was achieved initially; however, with continuous operation, a salt rejection as low as 83.5% and 69.9% was achieved when the seawater and the 100,000 ppm NaCl solution were used, respectively. PP membrane of 0.22 μm gave a better salt rejection followed by PTFE membrane of the same size then by PP membrane of 0.45 μm.
The contact angle of a clean PP membrane of 0.22 μm, PP membrane of 0.45 μm, and PTFE membrane of 0.22 μm, was found to be 134.8°, 133.2°, and 136.7°, respectively. However, after fouling, the contact angle dropped to 40.5°, 36.1°, and 13.8° for PP membrane of 0.22 μm, PP membrane of 0.45 μm, and PTFE membrane of 0.22 μm, respectively, indicating significant loss of hydrophobicity.
SEM-EDS analysis showed that the salt layer formed on the membranes was not uniform and that the major foulants were CaCO3 and CaSO4. In addition, membrane pore blocking by salts and a cake layer formation (which was a result of the elevated feed temperature that resulted in the formation of temperature polarization) were observed.
The results of the study show that fouling needs to be more investigated in MD process to be practically implemented and considered as competitive to the conventional desalination technologies. An optimum temperature and flow rate should be explored; however, the results of the study urge the need for developing new membranes and improved membrane modules and MD configurations as well as finding optimum procedures for membrane cleaning.
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Theoretical and Experimental Investigations on Passive Thermal Management of Solar Photovoltaic Systems using PCM-Metallic Cellular Absorbers
Authors: Abdelhakim Mohamed Hassabou, Torsten Klemm, Amir Abdallah and Olaf AndersenEnvironmental conditions such as irradiance, temperature, humidity and dust accumulation have impact on PV performance and reliability. In this paper, we will focus on the effect of temperature and how to mitigate this effect by using passive cooling approach.
Qatar is rich with solar irradiance favored for photovoltaic; however, the high temperature (a module temperature of 50°C was measured during summer months) has a negative impact on the power output of a PV module. Operation of solar PV systems under extremely high temperatures and high humidity in hot climates represents one of the major challenges to guarantee higher system's reliability. Therefore, thermal management in hot climates is crucial for reliable application of PV systems, as it has a potential to increase the efficiency and life expectancy and to stabilize the output power characteristics.
Apart from that, dust accumulation on PV module is known to be also as one of the challenges that affect the PV power output. Due to the difference in ambient temperature between day and night, water condensation on PV modules was observed. Dust accumulated on a PV module together with water condensation may cause a thick layer of mud that is difficult to be removed. In this paper, we will show that, condensation of water on the cell surface during night can be prevented by maintaining the temperature of solar PV panels above the dew point during night.
Application of Phase Change Materials (PCM) for passive or combined active-passive cooling systems offers various options for adequate thermal management solutions. The present research focuses on utilization of PCM for passive thermal management of solar systems. Passive cooling can be realized by integration of PCM layers with the back side of PV panels. Passive cooling use the high temperature differences between day and night in arid desert regions, due to sky radiation in the night. The high thermal capacity of PCM accumulates coolness during night to keep the PV cells at a moderate temperature during the day. This also can help maintaining the PV panel temperature well above the dew point to prevent condensation during day and night, thereby avoiding mud formation on the panel surface. In some instances, active cooling may still be needed during peak solar radiation hours around noon time in summer, however integration of PCM can also reduce significantly the pumping power required to circulate the cooling medium as well as the external thermal/cool storage size and cost.
Although PCM provides high energy storage density and nearly isothermal behavior around the phase change temperature, they suffer from low thermal conductivity, which limits the power density during charging and discharging. The low thermal conductivity of a PCM can be increased by combining them with highly conductive heat transfer structures. One advanced option is the application of cellular materials like metal fibers, which allow a significant enhancement of the PCM absorber thermal conductivity by more than 100 times. Hence it is proposed to hybridize PCM with cellular metallic matrices to enhance the thermal conductivity and provide a practical solution for easy encapsulation and integration with the PV panels.
The main focus of this study is therefore to explore the effect of utilization of PCM based cooling elements incorporating cellular metallic heat conducting structures on the thermal behavior of solar PV panels.
Preliminary laboratory experimental investigations have been carried out to characterize the thermal resistances between the PV panel and the PCM matrix absorber using different coupling mechanisms attached to the backside of PV panels. The coupling mechanisms include mechanical clamping, adhesive bonding, and double side thin and thick adhesive tapes. Based on the measured data, design recommendations for the desired performance will be discussed. The outcomes of the laboratory experimental investigations provide important input parameters that are needed in numerical analysis and design optimization of such systems under weather conditions in Qatar and elsewhere.
Beside the laboratory experimental work, theoretical analysis to optimize the properties of the PCM matrix absorber for application of solar PV systems in Qatar has been carried out. The simulation model has been developed using homogenization based on volume averaging techniques and interpenetration continua approach. Due to complexity of the underlying transport phenomena, solution of highly nonlinear coupled system of equations with moving boundaries is required as a function of space and time. Hence, numerical modeling and optimization of large scale PCM storage is both challenging and computationally expensive. However, in engineering systems microscopic details are neither easy to be captured nor needed, instead, the macroscopic aspects are much more interesting. Therefore, dealing with a large-scale PCM storage, a fundamental question arises as how to bridge the computational scale and reduce the problem to a simple one. A simplified modeling approach and numerical procedures shall be proposed to determine the macroscopic transport and time history of the PCM temperature field in a PCM thermal storage. The model is fairly general to be applied as a design and optimization tool for thermal energy storage and thermal management systems. Preliminary results of the numerical simulation shall be presented and discussed.
Due to similarity of climatic conditions in the GCC, the solution can be easily adapted to suit other countries in the Gulf. The fibrous porous structure can be manufactured using wastes of metals processing such as in manufacturing aluminum profiles. PCM candidates with low temperature and desired thermo-physical properties, such as paraffin waxes, are abundantly available with reasonable cost. Further cost reductions for manufacturing of PCM matrix absorbers can be achieved by integration with the PV support structure. This an important part of the ongoing research in collaboration with local industry partners in Qatar in order to produce these systems locally on a commercial scale effectively with lower costs. Preliminary analysis shows that the passive thermal management can increase both instantaneous conversion efficiency by 3–5%, while it can considerably increase the life span of PV modules and reduces maintenance and cleaning costs. These factors hold a great promise for supporting the economic viability of passive thermal management using PCM matrix absorbers. However, detailed technoeconomic analysis will be elaborated within the framework of this project and will be published later.
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Calibration & Temperature Controlled Setup for Air Quality Sensors
Authors: Ali Ijaz, Mohieddine Amor Benammar, Farid Touati and Abdullah KadriIndoor air pollution is a major issue affecting public health. Due to hot climate, humidity and lack of natural green spaces, life is mostly confined indoors in many countries of the MENA region. Vulnerable population, including young children and senior citizens who spend most of their time indoors, are at risk because of the effects of indoor air quality (IAQ) on their health. An indoor air quality monitoring system is a need of the hour to detect and improve Indoor Air Quality (IAQ). The monitoring systems presently available are bulky, expensive and need periodic calibration to maintain high degree of accuracy. Frequent recalibration of a number of densely deployed individual sensors in the network is a time-consuming and laborious task therefore self-calibration is indispensable. Gas sensors, even if factory-calibrated, tend to drift with time/usage. Therefore these should be regularly calibrated under controlled environments. Calibration may be carried out using test gas mixtures with known composition. Pre-mixed gas cylinders with known composition may be used for the purpose; however this solution is not flexible as the number of calibration points and testing conditions (e.g. effect of temperature and humidity on CO2 sensor) are limited. In the current project, a computer-controlled test and calibration test bed system is being designed and assembled along with temperature controller.
Calibration set-up would help in self calibration of the air quality sensors. Calibration curves obtained from proposed calibration test bed are updated automatically and fed into the sensor node through wireless communication without going in the field or replacing the sensor. A computer-controlled test and calibration test bed system is designed and assembled containing the sensor(s) under test and in which gas composition; temperature can be precisely and dynamically controlled. ATMEGA328 micro controller is used to receive the temperature set point from the computer running the test rig.
Gas composition, temperature and humidity can be precisely and dynamically controlled in our designed test chamber containing the sensor(s) under test. Given the number of air pollutants that may be present in the atmosphere, up to 6 different gases can be mixed to calibrate the sensor nodes and investigate the issue of cross-sensitivity.
Array of 6 gas cylinders, and a gas blending system that has been designed provides continuous variation of mixture composition and temperature. Gas blending is performed using mass-flow controllers, which control a number of different gas streams, including that of an inert gas or pure air. The composition of the test gas mixture resulting from blending is controlled by varying the flow of individual gas components through the mass-flow controllers. The test chamber is fitted with heating elements and temperature sensors to control the gas mixture temperature.
The gas composition is controlled by adjusting the flow of gases in each mass flow meter; the set points for these are controlled by a computer running under MATLAB/LABVIEW environment. Each gas line is equipped with the necessary safety valves (shut down valve and one way valve). Additionally, each line has a pressure gauge to monitor the inlet gas pressure.
The temperature controller was based on an Arduino Uno microcontroller, tow (2) driver modules that incorporate a H bridge (mosfet), four (4) heaters (each 100 W/24 V), an LM35 temperature sensor, and two (2) fans to ensure uniform temperature inside the test chamber.
The micro controller (ATMEGA328) receives the temperature set point from the computer running the test rig; then on/off control with hysteresis is used to control temperature from room temperature to 65 °C with a precision better than 1 °C; Hence temperature is precisely and dynamically controlled so that the sensors be tested under different temperatures.
Stainless steel tubes have been used for connecting the various parts. The sealed sensor test chamber included a door that incorporated a rubber seal; all connections to the chamber included rubber seal to ensure that the inner gas composition is controlled only by the mass flow controllers.
The inner walls of the chamber are covered with heat insulation material to minimize heat transfer from the chamber and thus minimize heating power requirements. The size of the chamber was selected to allow testing of a complete wireless sensor node that includes all air quality sensors.
Sensor measurement readings are compared with a professional air quality measurement analyser named “Gray wolf IAQ Monitor” (Acquired from USA) to verify the effectiveness of the proposed system.
In future, humidification of the gas mixture will be considered using different methods, including the saturation method based on water bubble technique. The system will have a fume hood (available in our labs) for safe extraction of gases out of the calibration lab. The test bed will allow:
Calibration of procured sensors and sensor nodes.
Checking sensors cross-sensitivity and effects of environmental conditions.
Training of ANN used with the array of sensors in each node to minimize cross-sensitivity.
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Novel Graphene-Zinc Iron Oxide Composite to Enhance Ultrafiltration Membrane Performance for Water Treatment and Desalination
The main target of membrane technologies such as the Ultrafiltration (UF), Nanofiltration (NF) and Reverse osmosis (RO) is to produce better filtration and separation of organic and inorganic substance from water as well as for longer life of the membrane. The phase inversion method is a well-known method to fabricate UF, NF and RO membranes for different application. The UF membrane is widely used in separation of macromolecules from solution as pretreatment stage with higher efficiency in hybrid process. The UF membrane made by pure polymer showed low flux, which affect on process performance of separation. The Polysulphone (PSF) is the most common polymer used in UF membrane which a hydrophobic material is making its surface prone to fouling due to adsorptive mechanism. This limitation of UF membranes have been solved by blended with nanoparticles incorporated membranes which showed significant enhancement on permeability, surface hydrophilicity, mechanical properties and other properties such as the selectivity. The main objective of this study to modify of UF membrane by blended with new composite nano-material for higher rejection of salt and organic substances. The graphene-zinc iron oxide composite as new nano-material was synthesized by sol gel method at low temperature of preparation. The composite was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) to show the structure, morphology and particle size of nanoparticles. Thermal decomposition was determined using thermogravimetric–differential scanning calorimetry (TGDSC). The results showed that cubic system of zinc iron oxide nanoparticles with 8 nm of crystal size was obtained using XRD. The morphology using TEM showed zinc iron oxide composite graphene as layer of nanoparticles with size lower than 10 nm which confirmed the XRD results. The novel synthesized of zinc iron oxide nanoparticles embedded in graphene incorporated into polysulfone (PSF) with 0.5 wt. % loading which significant impact on the UF membrane properties was investigated. The effect of composite additive on membrane properties was investigated in terms of permeability, hydrophilicity (contact angle), zeta potential, porosity and pore size. However, the membrane cross section, surface, EDX and mapping were also analyzed using FESEM include EDX analyzer. This composite incorporated PSF showed significant improvement in terms of surface hydrophilicity with reduction of about 25% (reduce contact angle from 82 to 62°). This improvement confirms by increasing the zeta potential values and surface negatively charge of blended PSF with composite compared to pure PSF membrane. The permeability results showed that significant increased more than two times compared to pure PSF membrane. The phenomenon of permeability increasing was attributed to increase of porosity of blended membrane which becomes lower resistance of water permeation. Generally, the rate of pore production has been reported directly affected by rate of solvent and non-solvent exchange in phase inversion process. However, higher rejections of organic substances such as the dyes and humic acid as well as the salt such as Sodium sulfate (Na2SO4) were maintained using UF at low pressure. This enhancement affects on time and load of process especially when hybrid with Nanofiltration (NF) which can increase of membrane life and reduce of overall process cost. The results of this study will have bigger impact in the future for different application including for water treatment and desalination.
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Determining the Outdoor Air Ventilation with Carbon Dioxide (CO2) as a Tracer Gas
Authors: Ali Ijaz, Mohieddine Amor Benammar, Farid Touati and Abdullah KadriInsufficient ventilation can lead to occupant complaints of discomfort and reduced productivity as human and building generated pollutants build up. Some combinations of these elevated pollutants may have short or long-term detrimental health effects.
Carbon Dioxide (CO2) is very rarely a pollutant of direct health concern itself. Rather a tracer gas, because building occupants exhale CO2 and is used as a tracer gas that is an excellent indicator of adequate (or inadequate) ventilation.
Keeping in view this fact we measured CO2 as a marker, or tracer gas, to determine the outdoor air ventilation (dilution air) rate in an occupied space.
Low CO2 concentration, when measured during periods of average and higher occupancy, implies that human generated pollutants are being properly diluted. And in the absence of a specific pollutant source, it is a rough estimator that the thousands of potential building generated pollutants are being dispersed. This makes it a key indoor air quality indicator.
US Occupational Safety and Health Administration (OSHA)
OSHA states that 1,000 ppm CO2 should be used as an upper limit for indoor levels, as a guideline for occupant comfort. >1000 ppm indicates inadequate ventilation; complaints such as headaches, fatigue, and eye and throat irritation will be more widespread.
American Society of Testing and Materials (ASTM International)
Studies have concluded that about 7.5 L/s of outdoor air ventilation per person will control human body odour such that roughly 80% of visitors will find the odour at an acceptable level. These studies also showed that the same level of body odour acceptability was found to occur at a CO2 concentration that is about 650 ppm (v) above the outdoor concentration.
Us Environmental Protection Agency (Usepa)
EPA Testing for Indoor Air Quality, Baseline IAQ, and Materials, 2009 states that “Acceptance of respective portions of buildings by the Owner is subject to compliance within specified limits of IAQ contaminant.
Levels and CO2 not to exceed 800 ppm”
Observations/Readings
Reading start time: 20-Oct-15 11:31:23 AM
Reading End Time: 03-Nov-15 08:13:43 AM
Average: 547
A study was carried out with IAQ Meter acquired from USA (GrayWolf IAQ Meter) that has capability to measure CO2 along with other pollutants in air. In this paper we would focus only on CO2 values as a tracer gas.
Data comprises more or less for 11 days. Out of these days comparisons are made for Carbon dioxide at a particular time and date with respect to the occupancy of the space (lab).
The max/min of the CO2 concentration is summarised as follow:
Carbon Dioxide ppm:
Min = 373 at 02-Nov-15 05:43:43 AM
Max = 1489 at 20-Oct-15 05:31:23 PM
Average = 546.6
The highest value of 1489 was attained on 20 Oct 2015 Tuesday. If we analyze the lab time table we notice in that time the lab was occupied by students which lead to the highest level of carbon dioxide as it's exhaled by humans.
Rise in carbon dioxide value is evident with the number of occupants in the lab. Carbon dioxide value increases with increasing number of people inside the lab. It starts to rise by 3.30 PM (Lab started) and reaches maximum value of 1489 ppm by 5.31 PM.
It gradually decreases as occupants leave by the end of the lab time.
Average = 546.6 is still within American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) guidelines i.e. 700 ppm
ASHRAE Standard 62.1-2013 suggests maintaining a steady-state CO2 concentration in a space no greater than about 700 ppm above outdoor air levels will result in a substantial majority of visitors being satisfied in respect to human bio effluents (body odor).
Carbon Dioxide (21st Oct Wednesday to 28th Oct Wednesday)
Same lab was occupied on Wednesday 21 October 2015 and 28th October 2015.
If we analyse the trends for CO2 for 21st Oct and 28th Oct (Wednesday) we found that it's quite similar. This is obvious. As per lab time table lab starts by 2.00 PM and ends by 4.45 PM.
We can clearly see the values on the graph for CO2 a start increasing once it's occupied by the students at 2.30 PM and continue to rise until it reaches 900 ppm. The values gradually decrease by 4.45 PM indicating that students started vacating the lab at its end time.
The typical CO2 concentration indoors will increase above outdoor levels depending on the balance between occupancy (as occupants are all exhaling CO2), and the natural and forced ventilation. While levels of 600 ppm to 1000 ppm are typical in office buildings, many factors may result in higher levels (e.g. inadequate ventilation, elevated outdoor levels), or in lower values (e.g. low occupancy at the time of measurement, over-ventilation).
CO2 proved to be a tracer gas as its concentration was affected by number of occupants. This gives a clear picture for the ventilation. If the CO2 concentration increases this means ventilation isn't adequate and if its below the documented value i.e 700 ppm that means the space is well ventilated.
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Enhancing Energy and Water Use Efficiency in District Cooling Plants, An Innovative Approach for Sustainability in Hot Arid Regions
More LessWith around 60–80% of electricity used for air conditioning, and around 99% of potable water production being supplied by desalination plants, sustaining life in Qatar, as well as GCC and hot arid countries around the world, is uniquely energy intensive.
As District Cooling Plants (DCPs) have a potential to reduce energy consumption and CO2 emissions, Qatar and GCC are continuously shifting paradigm towards adoption of DC plants to satisfy the rapidly growing demand in all sectors. However, DC plants usually rely on wet cooling towers for disposing the excess heat to the ambient. Thus the heat disposal is accompanied by considerable loss of fresh water, a common problem in hot arid countries with highest demand for air cooling and also relies on costly and energy intensive desalination processes for securing fresh water supply. In addition to this, evaporative cooling devices and wet cooling towers can spread humidifier fever, a serious health risk with similar symptoms as mild influenza, and Legionella, which can be deadly. Hence huge evaporation loss in densely populated urban centers in Qatar and GCC is an imperative environmental issue which necessitates effective and practical solutions.
This study presents an invention, which involves an innovative process called the “SELF-SUSTAINABLE DISTRICT COOLING AND DESALINATION (SSDD)”. The patented solution is directed to construct a totally new concept for maximization of water and energy use efficiency in district cooling plants in hot arid countries while preserving the environment. The system couples district cooling plants with polishing of treated sewage effluents (TSE) using hybrid reverse osmosis and thermal desalination technologies with the district cooling plant. The desalination process is equipped with a zero liquid discharge (ZLD) system to achieve full recovery of the TSE resource and eliminate the common environmental problem related to brine disposal. The invention closes the water and energy circuits in DC plants, which considerably enhances the overall water and energy efficiencies.
The techno-economic analysis of the SSDD technology has revealed a breakthrough in the technology in terms of reducing energy consumption by 20–30% and water consumption by more than 50%. Considering, for instance, a planned capacity of 1.6 million refrigeration ton DCPs to be added in Qatar by 2022, the SSDD can save up to 200,000 m3/day evaporation losses and 650 MW of electrical power together with elimination of water distribution power needed for pumping potable water from desalination plants to the DCPs. The total energy saving corresponds with 3.5 Million ton reduction of CO2 emissions and more than 1.5 Billion QAR/year excluding the environmental benefits. Considering the ambitious development plans of other GCC states, the SSDD technology may play a significant role in achieving sustainable development goals not only in the region but also worldwide. Thus it holds a great promise for energy and water securities as well as combating global climate change.
The new RO/ZLD concept can be used for applications other than DC, e.g. waste water treatment and reuse, aquifer recharge, football stadia, irrigation for the Qatar National Food Security Program (QNFSP). Moreover, this process can be applied around GCC, Middle East and North Africa (MENA) as well as other hot parts of the world.
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Engineering of High Performance Solar Cells for Harsh Desert Environment Applications
Two major environmental factors affect drastically the performance of photovoltaic (PV) panels in the Gulf region, namely the dust accumulation (soiling) and the temperature-induced voltage decrease leading to a power loss. During the last years, intensive R&D activity has been conducted both by the industry and academia to address these major issues. However, recent results obtained in laboratory show that the power loss induced by an increase of the temperature of the panel from 200C to 750C can be reduced by 250% in the case of heterojunction silicon cells as compared to conventional homojunction silicon technology. Consequently, the temperature coefficient of the conversion efficiency represents an important figure of merit for the energy yield of a given photovoltaic technology, especially if planned to operate in Gulf region.
In this contribution, we will focus on reviewing current strategies addressing temperature effects on PV panels performance. More specifically, we analyze the dependence of the key characteristics of the solar cells with respect to the temperature and minority carrier injection level, and how various layers making the structure of the device can be engineered in order to maximize the resistance of the cell to temperature degradation.
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The Impacts of Anthropogenic and Climate Change Forcings on Water Resources Demands and Availability in Jordan in the Near Future
More LessAbstract
The present paper evaluates the composite risk of anthropogenic and climate change on the future water status in Jordan during the period 2030–2050. The projected water status in the country is evaluated based on the more likely population growth and climate change scenarios. The most likely figure for the population of Jordan, excluding refugees from neighboring countries, in 2040 would be ∼15 million people. Given this likely projection, though conservative, annual water needs for the domestic sector alone are expected to be between 700 and 800 million m3, with the current level of water consumption. A rise in near surface air temperature by 2 °C and a drop in total precipitation by 15%, as projected by most Global Circulation Models, would diminish renewable water resources in the mountainous region by ∼ < /AσΣETHιγηλιγητ>25–40%, being more severe as aridity increases.
1. Introduction
There is almost a consensus among earth scientists that the buildup of greenhouse gases in the atmosphere is leading to a global warming. Documented evidence suggests that global temperature observed over continental and marine regions has been rising for the past several decades (IPCC, 2007). The increased air temperature will intensify the hydrological cycle due to increased water vapor release into the atmosphere. Recent unprecedented severe meteorological events such as large scale torrential rains in many parts of the world and the recurrent tropical cyclones invading the southern parts of the Arabian Sea could be cited as a strong evidence of a global climate change. A climate change towards warmer conditions is expected to increase precipitation over the Arabian Peninsula due to the northward extension of the Monsoon Trough which will enhance the Red Sea Trough during the transitional periods, Fall and Spring.
There is almost a consensus among most GCM that a global warming will be most severe in the eastern Mediterranean, with a significant drop in precipitation and a large temperature rise (Zhang et al., 2005; IPCC, 2007; Kelley et al., 2012). Model results suggest that near surface air temperature will increase by 2–3.5 °C following an equivalent doubling of Carbon Dioxide in the atmosphere (Kelley et al., 2012). The projections for precipitation amount, its temporal distribution and variability are not as certain. Due to the northward retreat of the polar front during the winter months, however, the eastern Mediterranean is expected to experience less cyclogenic activities, and as such less winter storms, leading to a precipitation decline (Schulz et al., 2008). It is also projected that the timing and frequency of precipitation in this region will be more erratic, less frequent but more intense. Statistical evidence show a strong reduction in the number of rainy days with precipitation in excess of one mm day-1.
Population growth adds another negative dimension to the water crisis. This includes more water demands for the domestic, agricultural, tourism, and industrial sectors. Additionally, increased population causes severe deterioration to surface and underground water quality through large scale land use changes, release of large volumes of waste, gaseous and liquid effluents and solid waste disposal. It is clear that anthropogenic and natural forcings work hand in hand to adversely impact Jordan's limited water resources. As such, two operational questions need to be answered:
1- What is the near future water needs in the country?,
2- What is the water availability for the near future following a climate change?
Answering these two questions adequately is essential for a better assessment of the relative impacts of climate change and population growth on water availability, demands, and stress during the near future. This projection can be used to minimize the potential risks of the projected climate change and population growth.
2. Current water availability in jordan
Around 70% of precipitation in Jordan falls in the winter months, December through February, due mainly to cyclogenic activities; the other 30% fall in the transitional periods. Average annual precipitation in the country ranges from a ∼600 mm in a small enclave in northwestern Jordan to less than 5 mm near the Saudi borders (Fig. 1). Additionally, this area receives large quantities of solar radiation year around due to persistently clear skies triggered by large scale subsidence. The combination of scanty precipitation along with a large global radiation enhances direct evaporation and substantially limits blue water availability. The average annual renewable water resources in Jordan are estimated at about 800–850 million cubic meters (M m3) (Ministry of Water and Irrigation, Jordan, 2015).
There is observational evidence that precipitation in the country is declining; Fig. 2 shows a time series of precipitation in two stations, one in northern Jordan during the period, 1945 through 2005, and the other one in central Jordan, Rabbah in the Karak Plateau. Both linear regression and Mann-Kendall non-parametric tests reveal that annual precipitation in all stations in the country is declining.
3. Future population
The population of Jordan experienced a large growth during the past 60 years due to natural growth and as a result of political conflicts. The population of the country, however, swelled by about 20 times during the past 60 years. The invasion of Iraq caused a mass movement of Iraqis towards Jordan. The current civil war in Syria paints another unpleasant, in fact very gloomy, portrait of the population dynamics in Jordan, with current population close to 11 million people.
The population growth was paralleled by a similar increase in irrigated agriculture. The area of irrigated lands in the Jordan Valley increased from ∼15 thousand hectares in the early 1960's to ∼38 thousand hectares in 2011. Likewise, irrigated agriculture in the desert region increased from virtually nil in the early 1970's to ∼17 thousand hectares in 2008 (Ministry of Water and Irrigation, 2012). The substantial increase in the irrigated agricultural land caused further demands on freshwater. The availability of irrigation water will shrink in the near future, however, because of growing demands on this resource from other sectors, mainly the domestic sector. The future water status in the country would indeed look quite bleak should population growth continues unabated and a climate change towards warmer and/or drier conditions prevail in the near future.
4. Future Water Needs
Official figures provided by the Ministry of Water and Irrigation, Jordan (2015) indicated that current domestic freshwater supply is ∼150 liters per person/day, which gives a total annual freshwater need of 370 M m3. Nowadays, with only 7.5 million inhabitants (excluding fresh refugees), most households in Jordan receive a specified amount of water during the summer months, and domestic water is supplied once (few hours) per week. Renewable water resources in the country were not enough to meet the water demands, and as such non-renewable fossil freshwater resources have been intensively exploited during the past several decades. These measures have caused steady drop in the level of underground aquifers and resulted in poor water quality. The Dissi Project, conveying fossil water is expected to provide freshwater for several decades before it dries up completely.
Projections based on future population growth scenarios indicate that annual domestic water needs alone will range from a minimum of 550 M m3 to a value close to 1100 M m3 by 2050. A more likely figure would probably be between 700–800 M m3. Thus, renewable freshwater resources of the entire country will barely meet domestic water needs even without a climate change.
Currently, the agricultural sector accounts for about 65% of total freshwater consumed in Jordan (MWI, 2015). Paradoxically, the amount of water allocated for irrigation must drop in the near future because of demands by relatively more needy sectors, the domestic one in
particular. Based on population growth alone, it is obvious that the future water status in the country looks quite bleak even without a climate change. Should the climate of the eastern Mediterranean become warmer and/or drier or both, the country will face a serious, probably tragic, freshwater dilemma in the very near future which will ultimately lead to economic, social and political unrest. The anticipated climate change will seriously influence the future water crisis in Jordan.
5. Projected climate change impact
A climate change in the eastern Mediterranean will impact water resources in at least three ways: 1) reduces blue water availability due to increase direct evaporation from soils, 2) intensifies irrigation water demands, and 3) increases evaporation losses from dams and open water canals. The impact of climate change on the available water resources in Jordan is investigated using a water balance model with a temporal resolution of one day. The model is run over the mountainous areas of Jordan where around 65% to 70% of blue water is generated (Oroud, 2015). A detailed description of the model is presented elsewhere (Oroud, 2008; 2011). Figure 4 shows the linkage between annual blue water availability and annual precipitation as calculated by the daily model. Conservative calculations show that a 2 °C temperature increase along with a 15% reduction in precipitation decreases water availability, on average, by ∼ 25%–40% depending on the level of aridity, being more sever as in more arid regions. This means that renewable water resources in the country following a warmer, drier climate will probably be between 500–650 M m3 by 2050. This conclusion is commensurate with those presented by other investigators (e.g., IPCCk 2007; Margane et al. 2008; Suppan et al. 2008; Giorgi and Lionello, 2008; Kelley et al., 2012).
Irrigation water needs under current climate conditions and following a climate change were simulated for the Jordan Valley using a spatially distributed daily model. Following a climate change, the irrigation water needs will increase by around 15%. This is equivalent to 40 to 50 M m3 of extra irrigation water needed to maintain the irrigation water demands in the Jordan Valley at the current land use regime.
References
Giorgi, F., Lionello, 2008, Climate change projections for the Mediterranean region, Global and Planetary Change, 63, 90–104.
Inter Governmental Panel on Climate Change (IPCC), 2007, The physical science basis, Geneva.
Margane A., et al., 2008, Water resources protection efforts in Jordan and their contribution to a sustainable water resources management. In F. Zereini and H. Hotzl (eds) Climatic Changes and Water Resources in the Middle East and North Africa, Springer, pp. 325–345.
Kelley, C., et al., 2012, Mediterranean precipitation climatology, seasonal cycle and trend as simulated by CMIP5, Geophysical Research Letters, 39, DOI: 10.1029/2012GL053416
Oroud, I. M., 2008. The impact of climate change on water resources in Jordan. In: F. Zereini and H. Hotzl (eds) Climatic Changes and Water Resources in the Middle East and North Africa, Springer, pp 109–123.
Oroud, I. M., 2012a, The relative impacts of climate change on water resources in Jordan, in: National Security and Human Health Implications of Climate Change (H. Fernando et al., eds.), DOI 10.1007/978-94-007-2430-3-31, Springer Science.
Oroud, I. M., 2012b, Climate change impact on green water fluxes in the eastern Mediterranean.: pp 3–15. In: Leal Filho, W. (ed) “Climate Change and the Sustainable Management of Water Resources.
Oroud, I. M. and Alrousan, N., 2004, Urban encroachment on agricultural lands in Jordan during the second half of the twentieth Century, The Arab World Geographer, 7, 165–180.
Oroud, I. M., 2015, Water budget assessment within a typical semiarid watershed in the Eastern Mediterranean, Environmental Process 06/2015; 3(2):1–15. DOI: 10.1007/s40710-015-0072-8
Suppan, P. et al. 2008, Impact of climate change on water availability in the Near East. In F. Zereini and H. Hotzl (eds) Climatic Changes and Water Resources in the Middle East and North Africa.
6- Schulz, O., Busche, H., Benbouziane, A. (2008) Decadal precipitation variances and reservoir inflow in the semi-arid upper Draa basin. In: F. Zereini and H. Hotzl (eds) Climatic Changes and Water Resources in the Middle East and North Africa, Springer, pp. 165–178.
Zhang, X., et al., 2005, Trends in Middle East climate extremes indices from 1950 to 2003. J. Geophys. Res. 110.
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Bio-Facades; An Innovative Design Solution Towards Sustainable Architecture in Hot Arid Zones
Authors: Fodil Fadli, Payam Bahrami, Irina Susorova, Meysam Tabibzadeh, Sara Zaina and El-Shaimaa El-EkhteyarThe United Nations forecasts that 70% of the World's projected population of nine billion people will be urbanized by the year 2050, a 51% increase from seven billion people urbanized as of 2010. The enormity of this total figure of 2.8 billion people moving into cities over the next 40 years is can be more clearly appreciated when converted into an annual rate of 70 million people per year, or a daily rate of nearly 200,000 people. This means that the human race needs to build a new city of more than one million people every week for the next 40 years to cope with this urban growth (UN, 2011).
Creating comfortable urban and building environments is challenging in hot climate conditions of many countries of the MENA (Middle East and North Africa) and Gulf region, such as Qatar. Hot ambient air temperature and a high level of solar radiation lead to large heat gains through building envelopes. In addition, heat gained by building surfaces is emitted back into the atmosphere which leads to the increase in ambient air temperature in urban environments. This phenomenon is often called the urban heat island (UHI) effect. As a result, buildings constantly have to rely on mechanical cooling systems in order to achieve comfortable indoor conditions. To balance the weather conditions of hot climates, buildings generally require a large amount of energy for cooling consumption.
Buildings located in hot and arid desert environment of the MENA and Gulf region traditionally relied on different passive measures and devices for cooling and ventilation. These passive measures based on natural phenomena included natural cooling and ventilation by wind, evaporative cooling from water, and shading from the sun. Typically, buildings combine a few passive cooling techniques that give a distinctive look to MENA region architecture in its multiple variations from North Africa to the Middle East, and from the Gulf to Levant countries. For example, buildings often include one or two wind towers that capture strong wind high above the roof and redirect it down into the building core for cooling and air circulation (Oliver, 1998).
The link between humans and nature becomes important as more than 50% of the World's population lives in cities. In the last 20 years as part of the environmental sustainability movement, there was a new interest in incorporating plants into building construction, including buildings with green roofs and green walls. The significant positive effects of vegetation and landscape elements on building thermal and energy performance and the urban heat island effect are well known. Many countries located in hot climates had the tradition to grow vines along building perimeters and above atria to provide shade from excessive sun exposure and to cool the air. The recent sustainability movement has renewed the interest in integrating plants into various architectural features, such as building roofs, facades, or atria. While green roofs covered with layers of vegetation have long been prominent features of buildings in many cities, green walls integrating plants into buildings’ vertical elements are still a relatively new architectural concept (Dunnett & Kingsbury, 2010). We can learn valuable lessons by adopting design concepts from indigenous buildings and architecture (Fadli & Sibley, 2009).
The purpose of this paper is to discuss the bio-facade concept and its benefits as an environmental solution for creating a sustainable architecture and urbanism in hot climate areas such as MENA region. Bio-facades can be considered to new or existing building construction of commercial, residential, and public buildings with great imagination by using such architectural features as green walls, hanging gardens, green roofs, or pergolas. In addition to their striking visual effect, vertical vegetation increases building energy efficiency, creates a positive effect on the psychological and physiological health of individuals, helps mitigate the urban heat island effect, reduces greenhouse gases, improves air quality by acting as a bio-filter, protects wall construction materials from ultraviolet radiation, reduces noise pollution, and creates natural habitat areas in cities. These benefits create a path towards making cities more environmentally sustainable. Bio-facades can be incorporated either into the traditional courtyard architecture or contemporary buildings to create a better microclimate, to provide shade, and to reduce energy consumption, enhancing the energy performance of building envelopes, the buildings themselves, and their surrounding environment.
The current study led by the authors, indicated that bio-facades can be used as an environmental sustainable solution for energy efficient building in different climates. This paper will answer the questions: “How does bio-facades may create sustainable architecture and urbanism in the hot and dry climate and what are their benefits?”, “how does bio-facades affect thermal and energy performance of buildings in the hot and dry climate?” Acknowledgements: “This research/publication was made possible by a National Priority Research Program NPRP award [NPRP-07-1406-2-507] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author(s).”
Note: This QNRF-NPRP funded project number 7-1406-2-507, titled “The design, development and use of innovative bio-green facades: towards improved urban microclimates and enhanced building thermal performance in Qatar” is a joint collaboration between Qatar University (QU), Optim Design Inc, Cyclone Energy Group, and Mingo Design LLC (USA).
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Life Cycle Assessment of Tall Buildings in Qatar, A focus on Construction Materials Use and Techniques
Authors: Fodil Fadli, Tommy Dacanay, Cristopher Moen, James Guest and Payam BahramiBuildings represent one of the most significant sources of negative impacts to the natural ecosystems on which Qatar's inhabitants health and environmental quality depend. The market has identified Qatar as one of the busiest construction areas in the world (Ibrahim 2011), While rapid economic development, population growth, and construction boom are positive indicators of growth, they may also present issues related to the negative impact on the socio-environmental components of cities. Such is the case of the Gulf Cooperation Council (GCC) countries where increasing economic prosperity has led to a surge in tall building construction and a sense of competition to erect the tallest skyscrapers in the world (Mahgoub and Abarra 2012).
While tall buildings are a source of national pride and cultural identity enabled by economic prosperity, they pose several challenges to integrate with the urban fabric of the city while also having a tremendous environmental impact. Tall buildings are especially massive consumers of energy (Ali and Armstrong 2008). They are the dominant elements in urban architecture due to their scale and purpose, and should be the focus of sustainable design. With large number of towers constructed and to be constructed in Al Dafna and West Bay areas of Doha, these buildings affect different aspects of the built and urban environment, i.e., city image, traffic, urban spaces and physical conform. Therefore, more architectural design strategies have to be planned well ahead in order to tackle the issues of sustainability and adaptability to climate change and to foster sustainable built environment in the state of Qatar.
With Qatar slated to host a ‘zero carbon’ World Cup in 2022, Qatar Green Building Council (QGBC) has set up a group to foster green infrastructure as a national resource. Qatar is utilizing Leadership in Energy and Environmental Design (LEED) and the Global/Qatar Sustainability Assessment System (GSAS/QSAS) to this end. Furthermore, shortages in raw materials between 2013 and 2017 are expected to challenge the construction sector, as the period is expected to be the peak for the sector. Therefore, the sector will have to bridge the gap during this period by mutual agreements with the companies in Saudi Arabia and the UAE (QCB 2012).
The objectives of this paper are as follows: 1- to Identify sustainability metrics for tall buildings with focus on construction materials and methods used in Qatar; 2- Explore existing literature and identify analogies in optimization consistent with design variables; 3- to examine sustainability of construction materials used in Qatar by utilizing software which is based on currently available databases to perform life cycle assessment.
To meet the objectivess described above, the currently available software platforms to perform life cycle analysis of building materials were explored. A commercial software, SimaPro, which utilizes the environmental impact database Ecoinvent, was chosen for its flexibility in defining custom mix designs for concrete, as well as database information on steel and many other building materials. With SimaPro, a sustainability model for concrete and steel was developed which reflects the environmental implications of manufacture of materials in Qatar as appropriate. Quantitative results from the model for the sustainability of constituents of building materials were extracted, to form the basis of sustainability metrics in the forthcoming tall building topology optimization protocol.
Furthermore, Blanco-Carrasco et al (2010) outline reduced use of Portland cement, increased use of alternate cementitious materials, and reduced water use to improve the sustainability of the concrete industry in Qatar. Using structural models and the SimaPro model, ultra-high performance concrete was explored as a potential solution for all these problems, to be applied in the gravity/lateral structural components of Qatar tall buildings. In addition to identifying a novel material which fits well with the current tall building designs of the region, the process of examining the structural and environmental improvements from using ultra-high performance concrete has resulted in the formation of a procedure to compare multiple materials used in Qatar.
This paper is a result of a funded research project by QNRF, entitled “Multi–Objective Tall Building Topologies – Optimizing for Structural Performance, Economy, and Sustainability” and a jointly collaboration between researchers from Qatar University, Virginia Tech, Johns Hopkins University, Optim Design Inc, and MZ & Partners.
“This research/publication was made possible by a National Priority Research Program NPRP award [NPRP- 7 - 1518 - 2 – 549] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author(s).”
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Development of a Life Cycle Assessment Tool for the Analysis of Food Production Systems within the Energy, Water and Food Nexus
Authors: Tareq Al-Ansari and Anna KorreAs the demand for services and products continues to increase in light of rapid population growth, it is vital to ensure the sustainability of the natural resources. Critical to this growth is the question of energy, water and food security. The systems representing these three resources are intrinsically interdependent where impact on any one of them will have a simultaneous impact in the remaining two. As such, there is a need to develop assessment tools that consider the interdependencies of energy, water and food (EWF) systems in order to ensure that system dynamics are understood and disturbances are avoided where possible. For instance, when evaluating the environmental performance of a food production system, aggregating the system in terms of its agriculture, water and energy components is critical to develop a lifecycle blueprint of the system. The EWF Nexus tool has been used to describe food security in Qatar from a local environment perspective. The tool is a culmination of well-established theories related to system design and analysis such as Industrial Ecology and LCA with emphasis on EWF inter-linkages. The modularity of the nexus model enables the integration of a variety of different technologies which promote the de-materialization of the system and the subsequent evaluation of different configurations. The basis of which is to identify and achieve maximum emission reduction. This paper reports recent work expanding the LCA modelling tool of the EWF Nexus developed by the authors (Al Ansari et al, 2015). Through the integration of greenhouse gas control technologies, sub-system analsysis and scenario development, the objective is to enhance the environmental performance of Qatar's food production system. Using de-materilization and waste minimisaiton strategies promoted by Industrial Ecology, the objective of EWF Nexus tool is to reduce environmental degradation in business as usual scenarios. This includes the integration of waste management strategies and technologies to reduce the overall life cycle environmental impact of the Qatar Food system. Waste management strategies and greenhouse gas control technologies are represented by additional sub-systems which convert waste material to energy and capture of CO2 from power generation. As part of the LCA, sub-system LCI models representing the EWF systems have been developed. The food portion of the nexus is represented by the production of fertilizers and agricultural activities such as the application of fertilizers and the raising of livestock. The livestock under management include broilers, dairy, beef, sheep and camels. The water portion of the nexus includes Multi-Stage Flash (MSF) and Reverse Osmosis (RO) for the production of water. Finally, the energy sub-system considers power generation from a combined cycle gas turbine plant (CCGT) and renewable energy from solar Photovoltaics (PV). Furthermore, a biomass integrated gasification combined cycle (BIGCC) is integrated to recycle solid waste into useful forms of energy to be re-used within the nexus. Finally, carbon capture (CC) technology is integrated to capture and recycle CO2 from both the CCGT and the BIGCC. The integration of CC with the BIGCC transforms the carbon neutral BIGCC process to a negative GHG emission technology with carbon capture and storage (BECCS). For the different scenarios and subsystem configurations considered, the global warming potential can be theoretically balanced (i.e. eliminated) through the integration of PV's, BIGCC and CC technology. The peak GWP, i.e. a fully fossil fuel dependent system, is recorded at 1.73 × 107 kg CO2 eq./year whilst the lowest achievable GWP is 2.18 × 107 when utilising a combination of PV, CC integrated with CCGT in addition to BECCS technology. The natural gas consumption to − 7.8 × 107 kg/year in the best case configuration achieving a credit. In the same scenario, the PV land footprint required is calculated to a maximum of 660 ha. The maximum theoretical achievable negative emission is 1.09 × 109 kg CO2/year.
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Carbon Dioxide Enhanced Oil Recovery and Storage: Experimental Investigation to Maximize Energy Resources while Reducing Carbon Footprint in Qatar
Authors: Ali Al-Menhali and Samuel KrevorQatar is the biggest exporter of liquefied natural gas, LNG, in the world and is a main oil-producing member of The Organization of Petroleum Exporting Countries, OPEC. A fossil fuel-based industry emerged around the ports of Ras Laffan and Mesaieed, Qatar's industrial cities, perusing industrial diversity and maximising the huge fossil fuel reserves that serve as the primary feedstock for the industrial sector. LNG, crude oil, and petroleum products has given Qatar a per capita GDP that ranks among the highest in the world with the lowest unemployment. This also has given Qatar a per capita CO2 emissions among the highest in the world. A recent report from The World Health Organisation, stated that the capital of Qatar, Doha, is one of the world's most polluted cities and its air ranked the 12th highest average levels of small and fine particles which are particularly dangerous to health [1]. The people and wise leadership of Qatar recognizes the significance of the problem and made environmental development one of the four pillars of Qatar National Vision 2030. The vision places environmental preservation for Qatar's future generations at the forefront. Qatar Carbonates and Carbon Storage Research Centre is an example demonstrating Qatar's commitment to preserve the envioronment by investigating and implementing key technologies such as carbon capture and storage (CCS) to address the next step in climate change. CCS in deep saline aquifers is an important process for CO2 reduction on industrial scales. The aim of CCS is to safely sequester CO2 generated from stationary sources, such as power-plants, into aquifers and depleted oil reservoirs. It is considered a valuable option to reduce greenhouse gases and has been proposed as a practical technology to tackle climate change [2–4]. The importance of CCS as a key option to mitigate CO2 emissions and combat climate change has been highlighted also in a report by the International Energy Agency (IEA) and suggests that CCS could contribute to a 17% reduction in global CO2 emissions by 2035 [5]. Previously, carbon dioxide injection into the subsurface has mainly been used for enhanced oil recovery (EOR) purposes. That gave rise to Carbon capture, utilization and storage (CCUS) processes in mature oil reservoirs where CO2 is first used to enhance oil recovery and then ultimately stored in the reservoir. The incremental hydrocarbon recoveries associated with CCUS make it more attractive to implement compared to CCS. It have significant energy, economic and environmental benefits and is considered an important component in achieving the widespread commercial deployment of CCS technology. Residual trapping of CO2 through capillary forces within the pore space of the reservoir is one of the most significant mechanisms for storage security and is also a factor determining the ultimate extent of CO2 migration within the reservoir. Observations and modelling have shown how capillary, or residual, trapping leads to the immobilisation of CO2 in saline aquifer reservoirs, limiting the extent of plume migration, enhancing the security and capacity of CO2 storage [6,7]. In contrast, carbonate hydrocarbon reservoirs are characterised by a mixed-wet state in which the capillary trapping of nonpolar fluids have been observed to be significantly reduced relative to trapping in rocks typical of saline aquifers unaltered by the presence of hydrocarbons [8,9]. There are, however, no observations characterising the extent of capillary trapping that will take place with CO2 in mixed-wet carbonate rocks, the same rock type found in Qatar's subsurface geological formations and many other giant oil reservoirs in the Middle East that hold most of the oil in the world [10, 11]. Experimental tests of CO2 and brine in carbonate rocks at reservoir conditions are very challenging due to the complex and reactive nature of carbonates when dealing with corrosive fluids pair of CO2 and brine. In this study, we compare residual trapping efficiency in water-wet and mixed-wet carbonates systems on the same rock sample before and after wettability alteration by aging with oil mixture of Arabian medium crude oil. The experimental work was conducted using a state of the art multi-scale imaging laboratory (core and pore scale) developed at Imperial College London designed to characterise reactive transport and multiphase flow, with and without chemical reaction for CO2-brine systems in both sandstone and carbonate rocks at reservoir conditions [12]. The flow loop included stir reactor to equilibrate rock with fluids, high precision pumps, temperature control, the ability to recirculate fluids for weeks at a time and an x-ray CT scanner and micro x-ray scanner for in situ saturation monitoring. The wetted parts of the flow-loop are made of anti-corrosive material that can handle co-circulation of CO2 and brine at reservoir conditions with the ability to preserve the rock sample from reacting to carbonic acid. We report the initial-residual CO2 saturation curve and the resulting parameterisation of hysteresis models for both water-wet and mixed-wet systems. A novel core-flooding approach was used, making use of the capillary end effect to create a large range in initial CO2 saturation in a single core-flood. Upon subsequent flooding with CO2-equilibriated brine, the observation of residual saturation corresponded to the wide range of initial saturations before flooding resulting in a rapid construction of the initial residual curve. Observations were made on a single Estaillades limestone core sample. It was made first on its original water-wet state, then were measured again after altering the wetting properties to a mixed-wet system. In particular, CO2 trapping was characterized before and after wetting alteration so that the impact of the wetting state of the rock is observed directly on both core and pore scales. A carefully designed wettability alteration programme was designed in this study to replicate a mixed-wet carbonate system similar to those found in Qatari oil reservoirs. At the pore level, oil can precipitate asphaltene and other heavy components after long exposure with the rock changing the wetting state of the surface to oil-wet. A mixture of the evacuated crude oil with an organic precipitant, n-heptane, was used to deposit a stable oil-wet film. The precipitant substituted some of the evaporated and oxidised light hydrocarbon originally existed in the crude and deposited asphaltene to generate a stable strongly oil-wet film layer. Filtration experiments were carried out to sensibly precipitate enough asphaltene for a stable and strong oil-wet film without over precipitating and causing fine migration that can damage the core sample. The weight fraction of asphaltene precipitated with different fractions of crude-precipitant mixtures were measured. The diluent consisted of toluene as the solvent and heptane as the precipitant. 40 ml of the diluent was thoroughly mixed with 1 ml of Arabian Medium crude oil at 11 different precipitant/solvent volume ratios ranging from 0–100% at 10% increments and then left in the dark for 48 hours to allow the system to come to equilibrium. The mass of precipitated asphaltenes was measured in each mixture by vacuum filtration using a 0.45 micron polytetrafluoroethylene hydrophobic filter paper (Millipore) and evaporation of any remaining liquid oil from the filter paper. No asphaltene was precipitated at low precipitant volume fraction and only above the onset of precipitation, a linear relationship was seen between the wt% precipitated asphaltenes and the volume % of the precipitant in the mixture. The onset for asphaltene precipitation for an oil mixture of Arabian Medium crude oil and heptane alone without solvent was calculated at the onset using the volume fractions of the components with the mixing rule. The sample's wettability was altered to a mixed-wet using the appropriate oil mixture as measured using the filtration test and the oil was then removed from the sample by CO2 enhanced oil recovery injected above the minimum miscibility pressure. This allowed for producing unique dataset and a great complement to the more theoretical analysis. That is if we make a surface oil-wet (to water), how does it behave in the presence of a gas. Here we show that residual CO2 trapping in mixed-wet carbonate rocks characteristic of hydrocarbon reservoirs is significantly less than trapping in water-wet systems characteristic of saline aquifers. We found that in the native water-wet state of the carbonate sample, the extent of trapping of CO2 and N2 were indistinguishable, consistent with past studies of trapping and multiphase flow properties in water-wet sandstones [13, 14]. After alteration of the wetting state of the same rock sample with oil, the residual trapping of N2 was reduced compared to the amount in the pre-altered rock. Surprisingly, the trapping of CO2 was reduced even further. The unique results were complemented with pore scale observations to investigate the balance of interfacial tensions and contact angles in three-phase flow. Our results show that one of the key processes for maximising CO2 storage capacity and security is significantly weakened in hydrocarbon reservoirs relative to saline aquifers. We anticipate this work to highlight a key issue for the early deployment of carbon storage – that those sites which are economically most appealing as initial project opportunities are the very locations in which the contribution of capillary trapping to storage security will be minimised. This should serve as a starting point for modelling studies to incorporate the reduced impact of capillary trapping on CO2 injection projects using hydrocarbon reservoirs.
References
World Health Organization. “Ambient (outdoor) air pollution in cities database 2014.” (2014).
Bernstein, L., P. Bosch, O. Canziani, Z. Chen, R. Christ, O. Davidson, W. Hare “IPCC, 2007: Climate Change 2007: Synthesis Report. Contribution of Working Groups I.” II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change, Geneva. http://www.ipcc.ch/ipccreports/ar4-syr.htm (2007).
Orr, F. “Storage of Carbon Dioxide in Geologic Formations.” Journal of Petroleum Technology 56, no. 9 (2004): 90–97.
Bachu, S., W. Gunter, and E. Perkins. “Aquifer Disposal of CO2: Hydrodynamic and Mineral Trapping.” Energy Conversion and Management 35, no. 4 (1994): 269–79.
IEA, WEO. “IEA World Energy Outlook 2012.” International Energy Agency, Paris France (2012).
IPCC, 2005. IPCC Special Report on Carbon Dioxide Capture and Storage, Prepared by Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom/New York, NY, USA.
Krevor, S., Blunt, M., Benson, S., Pentland, C., Reynolds, C., Al-Menhali, A., Niu, B., 2015. “Capillary trapping for geologic carbon dioxide storage -From pore scale physics to field scale implications”. International Journal of Greenhouse Gas Control, Volume 40, Pages 221–237, ISSN 1750–5836, http://dx.doi.org/10.1016/j.ijggc.2015.04.006.
Chillenger, V. and Yen, F. 1983. “Some Notes on Wettability and Relative Permeability of Carbonate Rocks”. II. Energy and Sources 7 (1):67–75.
Salathiel, A. 1973. “Oil recovery by surface film drainage in mixed-wettability rocks”. Journal of Petroleum Technology 25.10: 1–216.
Roehl, P., and Choquette, W., 1985, “Carbonate petroleum reservoirs”. Springer Science & Business Media.
Akbar, M., Vissapragada, B., Alghamdi, A., et al. 2000. “A Snapshot of Carbonate Reservoir Evaluation”. Oilfield Review 12 (4):20–21.
Al-Menhali, A., C. Reynolds, P. Lai, B. Niu, N. Nicholls, J. Crawshaw, and S. Krevor. “Advanced Reservoir Characterization for CO2 Storage.” International Petroleum Technology Conference, (2014).
Niu, B., Al-Menhali, A., and Krevor, S. (2015), “The impact of reservoir conditions on the residual trapping of carbon dioxide in Berea sandstone”, Water Resour. Res., 51, doi:10.1002/2014WR016441.
Al-Menhali, A., B. Niu, and S.Krevor (2015), “Capillarity and wetting of carbon dioxide and brine during drainage in Berea sandstone at reservoir conditions”, Water Resour. Res., 51, doi:10.1002/2015WR016947.
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Dynamic Tariff Development for Effective Demand Side Management (DSM) in the Presence of Increased Penetration of Photovoltaics (PV)
I. Introduction
The trend towards high penetration of renewable energy sources (RES) in the energy mix and particularly grid-connected photovoltaic (PV) systems in the low voltage (LV) network, offers the benefits of green decentralized generation, at the cost of the development of energy management tools to alleviate potential problems. More specifically, the fact that for most consumption profiles the PV energy production does not coincide with the electricity demand, forces the grid to act as a sink and a source thus requiring re-adaptation of the grid operation [1]. To this extent, an advanced demand side management (DSM) scheme can be introduced to mitigate RES operational issues and contribute to managing effectively congestion problems. In this work, a price-based DSM tool has been developed in order to arrive at an effective Time of Use (ToU) tariff with improved DSM results. In this scope, smart meters (SMs) have been deployed at three hundred households with grid-connected PV systems installed at their rooftops, in order to acquire consumption and production profile details of typical Cypriot prosumers. The selected pilot sites that already have a 3 kWp grid-connected PV system, have been offered a ToU tariff allowing rates and charges to vary based on the time and date of consumption, i.e. day or night and seasonality. This aims to examine how financial implications can alter the energy behavior of prosumers [2]. In addition, the prosumers are divided into three groups each receiving a distinct method of monitoring their energy habits: one group will have In-House Displays (IHDs), the other will have access through a web application, and the third will receive information about their energy habits through the traditional bi-monthly mail bill. This will facilitate an in-depth examination of the prosumers’ response based on the information sent to them [2].
II. Background
Theory Price-based DSM programs offer an alternative to the traditional flat tariffs and comprise of Critical Peak Pricing (CPP), Real-Time Pricing (RTP) and Time-of-Use (ToU) tariffs [3], [4]. Amongst the different schemes, ToU tariffs are commonly preferred because the price of energy consumption is fixed for different periods of the day in contrast to other price-based DSM programs where the price fluctuates following the real time cost of electricity [3], [4]. The development of an efficient DSM system offers the advantage of generating cost reductions for grid utilities and the increase of operational efficiency. However, in order to achieve a balanced DSM scheme, the existing flat tariffs need to be transformed to ToU tariffs providing the necessary monetary incentives for domestic consumers to flatten their load profile. Even though, ToU tariff schemes offer the advantage of price certainty, the effectiveness of such tariff schemes must be verified prior to implementation because of the risk of a new peak appearing through load shifts at cheaper price periods, posing negative effects on the optimal operation of the system [5]–[8].
III. Prosumer Features
In support of this work, three hundred prosumers in Cyprus have been selected through the implementation of the SmartPV project (http://www.smartpvproject.eu/), in order to acquire real-time information of the consumption and production profiles and to identify the potential problems and limitations of the existing energy policy. All participating prosumers are geographically spread in Cyprus, in order to cover different socio-geographical conditions and thus targets a variety of consumers. In addition, prosumers with higher total yearly electricity consumption (in kWh) compared to the typical energy production from a 3 kWp grid-connected PV system were selected.
IV. Methodology
The development of a dynamic ToU tariff tool to enable price-based DSM relies strongly on the analysis of the basic input parameters such as electricity demand and PV electricity production profiles. Consumption and production data acquired from the three hundred prosumers was used to optimize the dynamic ToU tariff algorithm for the case of Cyprus. It has to be pointed out that this is a benchmark tool which can be used by any other country. The first step in the development of the algorithm was to identify the maxima and minima power consumption periods of the provided average domestic consumption profiles, an approach already implemented and verified [9]. The load duration curve of the provided average domestic consumption profile in Cyprus for each season was analyzed in order to identify possible inflection points. The different inflection points of the curve represent the various load segments which were used in order to obtain the probability density function (PDF) (at a 95% confidence interval) [1]. The PDF of each segment represented the ToU block period. The dynamic tariff tool developed from the above statistical analysis is capable of deriving the ToU blocks with a mean absolute percentage error (MAPE) and root mean square error (RMSE) between the ToU block periods and the load profile of 8.65% and 19.95%, respectively [1]. In order to further improve the initial algorithm, a function based model was developed. Optimization methods were used in combination with the statistical results [1]. In this approach the statistical output ToU block periods are used as the initial condition of the optimization procedure using the Matlab Optimization ToolboxTM. The ToU blocks are directly compared with the load profile rather than extracting the ToU blocks from the load duration curve. The objective function of the optimization procedure minimizes the RMSE as described by (1): where is the derived ToU block period, is the load profile and is the total sampling interval. Based on this equation, is the variable to be optimized and changes according to the desired levels. To achieve this, the developed optimization tool uses a hybrid optimization function such as simulated annealing [10] and pattern search [11]. In summary, two different methods were used to derive the final ToU block periods: a) combining statistical analysis using the load duration profile and b) optimization methods applied to the load profile.
V. Results
A. Dynamic ToU Tariff tool A software application tool was developed in order to assist users to visualize the impact on their electricity bill from the different ToU blocks. The derived ToU blocks for the winter period were compared using two different approaches (figure 1). The MAPE and RMSE between the load curve and the ToU blocks were improved by utilizing the optimization tool reducing them by 2.43% and 7.63%, respectively when compared to the statistical approach. Furthermore, the optimization approach clearly demonstrated that the peak consumption period is charged with the higher tariff, while the lowest tariff occurs during the valley period. Through this approach another period is clearly identified representing the transitional period: from the minima to the maxima and vice-versa. These time periods are important as they can be used by prosumers to cover their needs that can be shifted from the peak periods but cannot wait until the off-peak period (e.g. cooking, devices without smart control etc). B. Acquired data from three hundred prosumers Data-sets collected during the summer period from the three hundred prosumers equipped with Smart Meters (SMs), before the application of ToU tariffs, were analysed in order to evaluate the self-consumption index. Figure 2 presents the consumption and PV production profiles from the pilot sites. The evaluation of the self-consumption energy was calculated using the equations below [12] and the results are presented in Table I. The average self-consumption energy for the participating prosumers during the summer months is calculated to be 738.87 kWh hence, 53.52% of the energy produced is directly consumed on site while the remaining energy is exported to the grid. Comparing this with the typical prosumer of Cyprus, the self-consumption rate is more than 10% higher. This is mainly due to the fact that the SmartPV sample has on average a higher load demand when compared to the typical prosumer.
VI. Conclusions
In this work, the application of DSM schemes aiming at raising the awareness of the consumers, coupled with financial incentives has been demonstrated through dataset collection from 300 prosumers. In this domain, a new tool for evaluating the dynamic ToU tariffs has been developed based on two different methods, in order to promote effective price-based DSM practices in the electricity network of Cyprus. This is based on statistical analysis of the provided average consumption profiles and optimization procedures, aiming to derive the most appropriate ToU tariffs. The statistical method showed a MAPE and RMSE of 8.22% and 19.95%, respectively, by comparing the resulted ToU blocks to the load profile. On the other hand, the optimization method resulted in a MAPE and RMSE of 6.22% and 12.32% respectively, proving its effectiveness and improved accuracy. In addition, energy data-sets have been collected from participating prosumers before the implementation of the ToU tariff and comparisons between measured data and a typical prosumer was made. The results indicated an average self-consumption index with the existing net metering scheme for the summer months of about 53%.
Acknowledgment
The project is co-financed by the program LIFE (LIFE+ Environment Policy and Governance) of the European Union under the grant agreement number LIFE 12/ENV/CY/000276.
References
[1] N. Philippou, M. Hadjipanayi, G. Makrides, V. Efthymiou, and G. E. Georghiou, “Effective dynamic tariffs for price-based Demand Side Management with grid-connected PV systems,” in PowerTech, 2015 IEEE Eindhoven, 2015, p. 5.
[2] B. Davito, H. Tai, and R. Uhlaner, “The smart grid and the promise of demand-side management,” 2010.
[3] M. H. Albadi and E. F. El-Saadany, “A summary of demand response in electricity markets,” Electr. Power Syst. Res., vol. 78, no. 11, pp. 1989–1996, Nov. 2008.
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[5] S. Gottwalt, W. Ketter, C. Block, J. Collins, and C. Weinhardt, “Demand side management—A simulation of household behavior under variable prices,” Energy Policy, vol. 39, no. 12, pp. 8163–8174, Dec. 2011.
[6] J. Torriti, “Price-based demand side management: Assessing the impacts of time-of-use tariffs on residential electricity demand and peak shifting in Northern Italy,” Energy, vol. 44, no. 1, pp. 576–583, Aug. 2012.
[7] J. Thumim, “Investigating the potential impacts of Time of Use (TOU) tariffs on domestic electricity customers Report to Ofgem,” 2014.
[8] C. M. Flath, “An optimization approach for the design of time-of-use rates,” in IECON - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013, pp. 4727–4732.
[9] Q. Hui-ting and L. Yi-jie, “Research of Peak and Valley Period Partition Approach on Statistics,” in 4th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies (DRPT), 2011, pp. 1774–1779.
[10] L. Ingber, “Adaptive simulated annealing (ASA): Lessons learned,” Invit. Pap. to a Spec. issue Polish J. Control Cybern. “Simulated Annealing Appl. to Comb. Optim., 1995.
[11] T. G. Kolda, R. M. Lewis, and V. Torczon, “A generating set direct search augmented Lagrangian algorithm for optimization with a combination of general and linear constraints,” 2006.
[12] O. Schaefer, S. Willborn, S. Goeke, J. A. Toledo, V. Cassagne, and A. Roesch, “Self Consumption of PV Electricity,” EPIA, 2013.
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Investigation Into the Effects of Non-Linear Loading of Domestic Power Network on Home Appliances
Authors: Ajad Hossain, Jassim Zaman, Mahmood Saeed, Atif Iqbal and Syed RahmanNon-Linear loads such as Compact Fluorescent lamps (CFLs), Light Emitting diodes (LEDs),Solid state voltage regulators, and variable speed electric drives are increasingly being added tothe domestic, residential and industrial power network. These light sources and other house-hold appliances using power electronic converters are termed as non-linear loads and they introduce distortion in the power network by generating harmonics in the current, leading to poor power quality [1 − 4]. Power quality issues are now becoming a major concern because of several reasons: a) Increasing dependence on electrical supply and even small disruption or interruption are not bearable because it can halt the modern lifestyle, b) new modern electrical equipment are highly sensitive to the power quality and c) the power electronic components such as variable speed drives and switched mode power supplies poses new disturbance challenges to the electrical supply network [5 − 7]. Power quality standards such as IEEE 519 is proposed to: a)assure that the electric supply company should deliver clean electric power to the consumers, b) assure that the electric supply company can protect electrical equipment from excessive voltage stress, overheating and loss of operational life of equipment. The IEEE 591 standard is in place that puts a limit on the allowed harmonic distortion of 3% on individual harmonic components and 5% on total harmonic distortion (THD). This standard is of utmost importance on the present day situation due to increasing non-linear loading. Although the distortion limits are not applied to specific equipment, however, with a high penetration of non-linear loads, it is likely that some harmonic suppression may be necessary [8 − 12]. The power quality problem is a distortion in the voltage waveform of the power source which is deviation from sine wave. Another power quality problem is a change in the amplitude from an established reference level. Other disturbance can be caused by harmonics in the current. With increasing the number of harmonics generating devices in a power system network, the problem of their impact on the performance of system components like induction motors needs is becoming a serious problem that need further consideration. It is well known that approximately 60–70% of loads in all over the world are motor loads. Most of the motors used in the world are three-phase induction motors. However, single-phase induction motors are major load in a domestic or residential setup. The modern day home uses large number of house hold appliances that uses different kind of single-phase motors as given in Table 1. A power network is shown for a domestic house in Fig. 1. Mix of loads are connected across the line. The effects of increasing non-linear loads in residential setting can be significant especially on single-phase motors connected to the same line. This paper investigate the effect of increasing distortion in the supplied voltage on the performance of single-phase induction motor behavior. Firstly the effect of increasing distortion in the applied voltage waveform on stator current is investigated. It is found that increasing a small %age of 3rd harmonic in the applied stator voltage significantly increases the 3rd harmonic component in the stator current. When voltage is pure sine wave, the current contains 1.7% 3rd harmonic. When the stator voltage is injected with 2.5% of 3rd harmonic the resulting current contain 11% 3rd harmonic. Hence it is concluded that current harmonic content is strongly dependent on the harmonic content in the stator voltage waveform. A Matlab/Simulink model is developed with single-phase capacitor start machine. The procedure adopted is as follows:
• Pure sine wave is applied to a capacitor start single-phase induction motor.
• Distorted supply is produced from inverter using appropriate PWM scheme and supplied to a capacitor start single-phase induction motor Non-linear loads such as CFLs and LEDs are emulated using thyristor based converter.
The thyristors are switched at different firing angle in order to vary the harmonic content in the supply voltage. The behavior of single-phase induction motor under distorted voltage conditionis recorded. The setup shown in Fig. 2 is consist of a single phase capacitor start induction motor supplied with PWM Converter. The motor is rated for 110V rms, 1500 rpm and 0.5 HP. The reference of the converter is generated by adding 3rd and 5th harmonic component to the fundamental component. The loads are switched in this order: Fig. 2. Single-phase induction machine (capacitor start) setup. a) At t = 0, the controlled rectifier with thyristor switching at 30° is turned on. This rectifier will always be on. The current drawn from the supply is analyzed for harmonic components. Each harmonic component contribution becomes input for reference generation for PWM Inverter. b) At t = 2 Sec, the controlled rectifier with thyristor switching at 60° is turned on. Now we have two controlled rectifier connected to the same ac supply. The resultant current is analyzed for harmonic component contribution. c) At t = 4 Sec, the controlled rectifier with thyristor switching at 90° is turned on. d) At t = 6 Sec, the controlled rectifier with thyristor switching at 120° is turned on. Efficiency estimation, a) The output of the system is calculated by multiplying load torque with the motor speed (in rad/sec). b) The input of the system is calculated by extracting P, Q, S from the bridge output voltage and current drawn by the motor from the block as shown below in Fig. 3. Efficiency computation of a single-phase capacitor start machine. c) Fundamental frequency, 3rd harmonic and 5th harmonic power is estimated by using the above block. The resultant power is calculated as: d) With the resultant absolute power drawn from the system, efficiency is calculated as: The simulation results are presented in Fig. 4–6. Ripple is seen in the current, torque and speed when voltage is distorted. The FFT of stator current (main winding) is shown in Fig. 7. Strong 3rd harmonic current is seen and also 5th harmonics.Sinusoidal Supply: Fig. 4. Single-phase IM behavior when pure sine wave is applied. Supply from a single-phase Inverter with Fundamental frequency (50 Hz) only: Fig. 5. Single-phase IM behavior when supplied from a DC/AC inverter. Supply from a single-phase Inverter with Fundamental, third and fifth harmonic: Fig. 6. Single-phase IM behavior when supplied from a DC/AC inverter with distorted waveform Fig. 7. Harmonic spectrum of stator current under distorted voltage source. Different powers are measured and shown in Fig. 8 for pure sine-wave supply and distorted voltage supply to a single-phase capacitor start induction machine. It is observed that the requirement of active, reactive and apparent power increases and efficiency decreases with the increase in the voltage distortion.
Acknowledgment
This publication was made possible by UREP grant # [17-061-2-017] from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.
References
[1] B.K. Bose, “Global Energy Scenario and Impact of Power Electronics in 21st Century”, IEEE Trans. On Ind. Elect. Vol. 60, Issue. 7, pp. 2638–2651, 2013.
[2] J. Mc Calley, V. Krishnan, K. Gkritza, R. Brown, D. Mejia-Giraldo, “Planning for the Long Haul: Investment Strategies for National Energy and Transportation Infrastructures”, IEEE Power and Energy Magazine, Vol. 11, Issue 5, pp. 24–35, 2013.
[3] M.K. Richard, P.K. Sen, “Compact Fluorescent Lamps and Their Effect on PowerQuality and Application Guidelines”, IEEE Industry Applications Society Annual Meeting (IAS), pp. 1–7, 2010.
[4] C. Keyer, R. Timens, F. Buesink, F. Leferink, “DC pollution of AC mains due tomodern compact fluorescent light lamps and LED lamps”, Int. Symposium on Electromagnetic Compatibility (EMC EUROPE), pp. 632–636, 2013.
[5] A.M. Eltamaly, “Power quality considerations of heavy loads of CFL on distribution system” IEEE Int. Symposium on Industrial Electronics (ISIE), pp. 1632–1638, 2011.
[6] Kesharvani, S.K.; Singh, A.; Badoni, M., “Conductance based fryze algorithm for improving power quality for non-linear loads,” in Signal Propagation and Computer Technology (ICSPCT), 2014 International Conference on, vol., no., pp. 703–708, 12–13 July 2014.
[7] Pattnaik, M.; Kastha, D., “Power quality improvement in a speed sensorless stand-alone DFIG feeding general unbalanced non-linear loads,” in Renewable Power Generation Conference (RPG 2014), 3rd, vol., no., pp.1–6, 24–25 Sept. 2014.
[8] Sharma, R.; Singh, A.; Jha, A.N., “Performance evaluation of tuned PI controller for power quality enhancement for linear and non linear loads,” in Recent Advances and Innovations in Engineering (ICRAIE), 2014, vol., no., pp. 1–6, 9–11 May 2014.
[9] Singh, A.; Baredar, P., “Power quality analysis of shunt active power filter based on renewable energy source,” in Advances in Engineering and Technology Research (ICAETR), 2014 International Conference on, vol., no., pp. 1–5, 1–2 Aug. 2014.
[10] Priyadharshini, K.M.; Srinivasan, S.; Srinivasan, C., “Power quality disturbance detection and islanding in micro grid connected distributed generation,” in Computational Intelligence and Computing Research (ICCIC), 2014 IEEE International Conference on, vol., no., pp. 1–6, 18–20 Dec. 2014.
[11] Arya, A.K.; Manocha, A.K.; Arya, J.S.; Kumar, M., “Compensation scheme for power quality improvement in present power system,” in Engineering and Computational Sciences (RAECS), 2014 Recent Advances in, vol., no., pp. 1–6, 6–8 March 2014.
[12] Ejlali, A.; Arab Khaburi, D., “Power quality improvement using non linear-load compensation capability of variable speed DFIG based on DPC-SVM method,” in Power Electronics, Drive Systems and Technologies Conference (PEDSTC), 2014 5th, vol., no., pp. 280–284, 5– Feb. 2014.
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Investigating the Effect of High Pressures and Temperatures on Corrosion Inhibition for Water-Based Muds
Authors: Abdul Salam M. Abd, Abdulrahman Al-Hardan, Alireza Roustazadeh and Mahmood AmaniCorrosion is defined as gradual degradation of metal caused by a chemical or electrochemical reaction with its environment. In oil and gas sector, components can corrode at any stage in the life of a field starting from drilling through to abandonment. Recent estimations showed that corrosion costs the oil industry in US yearly around $170 billion. In general, 50% of the operating expenditures in the drilling sector worldwide are for taming corrosion in drill pipe and down-hole equipment. On the other hand, “a corrosion inhibitor is a substance when added in a small concentration to an environment reduces the corrosion rate of a metal exposed to that environment. Inhibitors often play an important role in the oil extraction and processing industries where they have always been considered to be the first line of defense against corrosion” (SLB Glossary). Since corrosion process in mostly due to chemical reaction on the surface of the metal under HPHT condition, water-based mud properties used are hence greatly affected. Mitigating corrosion is a very serious challenge for oil and gas industry as it can't be totally eliminated. Because it is almost impossible to prevent corrosion, it is becoming more apparent that controlling the corrosion rate may be the most economical solution. Thus, the first step to tackle this problem is by determining the cause of the corrosion itself. This is vital as it helps understand the mechanism and the process behind corrosion to suggest more practical and helpful solutions. The corrosion has to have 4 main elements to happen: anode, cathode, electrolyte (Fluid) and external connection. In case any of these elements is absent, corrosion will not take place. In our research, Water based mud is the electrolyte of interest. In general, water helps in speeding the corrosion of metal where the steel itself serves as the external connection. The rate of corrosion depends purely on the grade of the metal and the generated potential due the dry cell effect. Oxygen (O2) which plays an important role in corrosion is only present at the drilling stage and not in the producing formations. Water and Carbon dioxide (CO2) injected at recovery operation can cause severe corrosion of completion string. Also, the presence of hydrogen sulfide (H2S) gases at HPHT has a major role in the dynamics of corrosion. Thus, finding the effect of those elements (O2, CO2 and H2S) in the corrosion process is the main focus of our research. First, the most common element that interfere in the corrosion process is the dissolved oxygen. The reaction of the iron to the oxygen contained in water will form iron rust. The equation below shows the reaction governing the process: 2 Fe+++ ½ O2 + H2O = 2 Fe++++ 2 OH− . The formed rust is called ferric hydroxide which is characterized as insoluble. While drilling, we will have infinite oxygen as it is an open system operation, thus the corrosion will not cease. The corrosion rate is usually higher when the concentration of oxygen is low thus leading to rust that is impermeable to O2 diffusion compared to that at high O2 concentrations. Second, the presence of dissolved CO2 in water causes the steel to corrode where the rate of corrosion depends mainly on the quantity of CO2 and O2 present as well as temperature and composition of the material. This reaction is weaker than that induced by the presence of O2 for equal quantities. In CO2 based corrosion, carbon dioxide reacts with water to form bicarbonate. The following equation governs the reaction: 2CO2 + 2H2O + 2e- = 2HCO-3 + H2. This equation indicates that the CO2, upon dissolving in water, acts like an acid. Thus, if we have dissolved CO2 and O2 combined in water, stronger corrosion rates will be observed. Third, dissolved H2S can be corrosive if dampness is present. The fact that H2S is highly soluble in water creates a weak dibasic acid, which causes the degradation of iron because of the presence of oxygen. The reaction will be as follows: H2S + ½ O2 = H2O + S. The rate of corrosion is controlled by the concentration of the dissolved gas. If the dissolved H2S is present in low quantities the corrosion will be severe. However, if the concentration of the dissolved H2S is very, it might have reverse effect where it will act to inhibit the corrosion reaction. When both CO2 and H2S are present, while having direct contact with O2, there will sever localized corrosion damage causing the material to crack and fail (Bonis 2014) To go further with the influence of external factors on corrosion rate, we should consider the temperature of the medium. We should not only consider the fact that the reaction rate will increase simultaneously with temperature, but we should account for solubility and viscosity. The solubility of gases in water will decrease with temperature increase as well as the viscosity. However, this is scenario is not true in all cases. For example, when dissolved oxygen is present, the corrosion rate will increase with temperature till a critical point then it will start decreasing with oxygen solubility. If the system is open, the oxygen will escape. Otherwise, the oxygen will be trapped causing the rate of corrosion to increase at high temperatures. Nowadays, the urge to drill deeper to recover larger amounts of hydrocarbons exposes the drillers to High pressure/High Temperature (HPHT) zones. Wells with temperatures greater than 300F and pressures of 1000 psig are classified as HPHT wells. (Bronlee 2005). Moreover, using water based muds (WBM's) will increase the likelihood of a severe corrosion to happen under HPHT conditions. This research is vital to the oil industry as it discusses a problem that has been ongoing for a long time. Corrosion is causing the oil companies a tremendous economic loss. In some cases, and in order to continue the drilling process, the tubing should be changed completely. There have been a lot of experiments on how to mitigate corrosion; however the success rates are still low. Corrosion cannot be inhibited completely; however the aim is to control it. Adding special additives to the drilling fluid or coating the tube with certain chemical are some ways to stop corrosion. The aim of this research is to subject various metal samples of different grades to stress and strain similar to those caused by severe HPHT condition downhole, and compare the results of two main categories: treated samples and untreated samples. The metals are expected to handle more stress when treatment is applied, proving the efficiency of the corrosion inhibitors compare to untreated samples. The challenge is to be able to manufacture an inhibitive chemical that can provide long term resistance as well as durable adherence on the steel. In the laboratory, a drilling water based fluid was prepared using mainly Drill water, Barite and Bentonite. Other additives such as NaCl, Flowzan, Soda Ash and Fine CaCO3 were used as well. Also, different corroding solutions with varying composition were prepared and stored in plastic vessels. The vessels were divided mainly into categories of mediums based on temperate: ambient and HPHT. The samples were prepared specific for each medium. 15 corrosion rings were cut into 4 pieces in Texas A&M University – Qatar machine shop. The initial weight of each sample was measured using a high accuracy electronic balance. The purpose of the Initial weights is to determine the loss after all exposure and treatment operation. This will also help us understand how the condition of each set-up affects the corrosion rate. One sample (1/4 of a corrosion ring) was immersed in each of the two mediums. The variation between the different samples was mainly the size of the corrosion ring, the type of inhibitor used and its concentration. Each sample of mud will contain each size of corrosion ring to determine corrosion accumulation and inhibition based on the size and type of corrosion ring. After approximately 100 hours of exposure, all corrosion rings will undergo the same procedures of inspection for the evaluation of the results. The weight of each sample was recorded before being immersed in the corrosion mediums and after their removal and cleaning From the weight data collected, the corrosion rates was estimated. The initial results showed that when only water based mud is presented without any type of inhibition, the corrosion rate is severe in HPHT medium (4.1 lbs/ft2-year) compared to ambient temperature conditions (2.2 lbs/ft2-year). Moreover, the corrosion rate is less whenever we have a thicker pipe. When adding inhibitor Concor 404 to our media, we see that the corrosion rate diminishes significantly at HPHT for the all corrosion ring sizes compared to base fluid media. On the other hand, using another inhibitor OS1-L will mitigate the corrosion effect in HPHT temperatures to around 1.3 lbs/ft2-year for corrosion ring of size 5.5”. This value is almost triple the rate that we got when using Concor 404. Hence, we deduce that Concor 404 is more effective than OS1-L while using water based mud. In the last batch of samples, Concor 404 and OS1-L were applied together to compare there raltive effect to each other. The inhibition effectiveness was still high under HPHT (around 1.1 lbs/ft2-year) but less than Concor 404 alone and more than OS1-L. It can be deduced that the presence of OS1-L is inhibiting the Concor 404 to perform in full capacity thus lowering the mitigation effectiveness. In general, all three inhibitors with their different combinations work efficiently in mitigating the corrosion. The final decision on whether to choose this inhibitor or the other should be merely based on a thorough economical analysis that includes your needs and takes into consideration your requirements.
Acknowledgement
“This report was made possible by a UREP award [UREP 17 – 133 – 2 - 034] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author.”
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Experimental Investigation of Permeability and Fluid Loss Properties of Water Based Mud Under High Pressure-High Temperature Conditions
Authors: Ahmad Amra, Mahmood Amani, Rommel Yrac, Dawod Hjeij, Ahmed Abdelrauf and Jana MahfouzDrilling in deeper formations and in high pressure and high temperature (HPHT) environments is a new frontier for the oil industry. Fifty years ago, no one would have imagined drilling in more than 10,000 feet of water depth like we do today. However, more issues need to be researched, tested, and studied in order to maintain a good drilling efficiency as deeper depths are drilled. One of these issues is the great effect that drilling at HPHT conditions has on the behavior of drilling fluids. The goal of this research was to study fluid loss properties of water based mud and its effect on permeability under HPHT dynamic conditions utilizing advanced laboratory equipment that allows for wide ranges of pressure and temperature. Filtration tests were performed at both ambient and HPHT conditions. After several laboratory evaluations of fluid loss additives available in the market, Polysal HT was found to be the most effective in reducing the fluid loss of the water based mud for both static and dynamic tests at HPHT conditions. It is economically designed to be saturated in salt and other brine system. An additive that encapsulates particles with protective polymer coating as colloid. Drilling fluid stabilizer especially in drilling hydratable shale and a remarkable effectiveness in wide range make up water (high saline and high hardness). The fluid loss behavior of the mud and the characteristics of the filter cake produce dare the basic factors that need to be considered when determining mud treatment. A detailed workflow of experiments using equipment from OFITE HPHT Fluid Apparatus with differential pressure of 500 psi under 230 °F with 2.5” filter paper (30 minutes) as well as OFITE Permeable Plugging Tester with 1,200 psi differential pressure @ 230 °F using a ceramic disc were conducted. Also tests were conducted using the Low Temperature- Low Pressure API Filter Press at 100 psi @77 °F with 3.5” filter paper for the purpose of comparison. Drilling fluid behavior should be studied and researched in order to get better drilling efficiency and less fluid losses. This topic has been for years the subject of research and many laboratory studies. Most of these studies focused on the methods and parameters involved in the study of drilling fluid characteristics. Mud can act unexpectedly under HPHT conditions and testing its properties at these conditions produces results that differ from those obtained from testing under static conditions. Drilling fluids' interaction with the spacer fluid is also critical. Krueger found out that the API filter loss tests (standard and high pressure) shouldn't be considered accurate when testing for the losses in mud that has viscosity reducers under dynamic conditions. He also studied the quantities of dynamic fluid loss in water based muds when adding substances to the drilling fluid such as CMC, starch, polyacrylate, and viscosity reducers. He found that–in dynamic system-starch and viscosity reducers were the most useful additives. However, when using API fluid test, the results deduced that CMC, starch and polyacrylate were the most beneficial additives. So he deduced that industry was paying so much on the API filter loss test (standard or at high temperature high pressure) expecting it to be accurate, instead of focusing on the dynamic filtration tests (at HPHT) whose results were more accurate since their conditions were very similar to the reservoir conditions. This is an experimental study of the impact of having HPHT reservoirs on the drilling fluids loss. Three different cases will be studied at different conditions. An API Filtration and fluid loss equipment will be used in order to test the mud capacity to withhold its filtrates under the HTHP as well as from static to dynamic condition. Experiment #1 consist of low pressure, low temperature conditions. The second one is at HTHP using static model. Finally, the last experiment will also be at HTHP conditions but using a dynamic model. Fluid loss models (beyond the conventional such as viscosity, gel strength, yield point and so forth) will then be compiled. The Polysal HT, a modified starch that serve as the fluid loss control additive along with Bentonite and Polypac UL will generally do the job. Roodhart stated that the commonly used 30 minutes API filtration test was inadequate especially in dynamic conditions. Also, he concluded that the range for fluid data testing (1,000 psi [7-MPa] differential) was lacking and deficient. Shadravan and Amani investigated the HPHT challenges in drilling and completions. Lee et al. researched the rheological properties of an extreme HPHT drilling fluids. Amani et al. compared the rheological properties of oil based and water based drilling fluids under HPHT conditions. Shadravan et al. looked at the possibility of fluid loss in underbalanced situations. Bland et al. mentioned that there were many parameters that need to be taken into consideration while designing and monitoring drilling fluids for HPHT conditions. These parameters included pressure and temperature effects on hydraulic calculations (while drilling under HPHT conditions at large depths, mud is subjected to high pressures and temperatures for long period of time) and PVT behavior of the base fluid (where the usual conditions considered by industry in fluid PVT measurements ranged from 15 psi per 750 °F to 20,000 psi/350 °F, but this range was exceeded while drilling under HPHT conditions). In addition, drilling efficiency was affected greatly by HPHT conditions where the use of additives like barite to increase the mud weight for such conditions caused lower drilling efficiency where the percentage of dispersed solids increased. This has many disadvantages (like decreasing hydraulic and cutting efficiency) during drilling high compressive formations under HPHT conditions. Elkatatny and Nasr-El-Din studied the formation of filter cake under static and dynamic conditions. They deduced that the same filtrate quantity was formed during dynamic and static conditions. However, dynamic conditions' spurt volume exceeded that under static conditions and when the filtration process reached an end, the part of the filtrate near to the drilling fluid had zero porosity and permeability. Further results by the CT scan proved that ceramic disk properties (like permeability and porosity) varied significantly during filtration and this should be taken into account during filter cake calculation. Properties of water based drilling fluids under HPHT dynamic testing conditions that can be measured include spurt loss, quality of plugging, total fluid loss, and cake formation thickness. Crespo et al. looked at some fluid loss related problems such as formation fracture, lost circulation, and well-control problems as a result of surge and swab pressures for yield-power-law drilling fluids. As the results show, permeability is proportional to the flow rate per unit cross sectional area. This can be translated into pore throats in subsurface rock. Therefore, the greater the pore size through which the fluid is going to flow at a constant flow rate, the higher the capacity of the fluid to flow and therefore its permeability. It can be deduced that as the concentration of the Polysal HT increased, less and less filtrate was lost into the formations. Same results were obtained from the low temperature low pressure API test where smaller filtrate volume was obtained as the concentration of the used Polysal HT increased. Thus, water based mud under HTHP conditions undergoes many changes in its main parameters like spurt loss, fluid loss, and filter cake thickness. Fluid loss control additives are therefore required in order to handle these changes and maintain the required properties of the used drilling fluid where Polysal HT was the required additive in this case. Dynamic as well as static API filtration tests should be performed before choosing the best additive. Numerous trials has been set up to test the fluid loss effectivity of the mud used in drilling but a very limited resources targeted the HTHP course due to its collaborative safety and productivity concerns, they call it “Drilling in the Dark” (a time to time check of properties).
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Investigating Recycling Practices in Qatar's Hotel Industry – A Study Focusing on Food Waste Measurement and Reduction
More LessThe year of 2015 is set to be a milestone for sustainability as governments are increasingly called upon to adopt the UN Post-2015 Development Agenda. Tourism has the potential to contribute directly and indirectly to the Sustainable Development Goals. Particularly, Tourism is seen to be able to play a key role in adopting and implementing sustainable use and management of natural resources, through environment-friendly practices and solutions. Hotels and Food and Beverage business (F&B) are one of the most important components of the tourism sector. Large number of visitors and guests visit hotels and F&B businesses, and waste is automatically generated. Qatar's tourism sector is amongst the fastest growing globally, and the number of tourists that Qatar aims to attract by the year 2030 is projected to reach seven million. The growth in the sector equally means a similar (and natural) increase in the waste generated. Handling solid waste has remained one of the main problems that directly affect the environment. Mismanagement of waste endangers the health of populations especially ones residing near landfills. The problem this research identified was the lack of data and information much needed for policy recommendation addressing recycling of different materials including Food Waste in the hotel industry in Qatar. This study was primarily set up to achieve two folded goal. First, it aims at exploring the current practices within the Hotel Industry in Qatar regarding recycling of waste materials including food. Second, it examines the effect of awareness on Food Waste reduction. To achieve these goals, first, a survey questionnaire was designed to gather the information from a number of 111 hotels (including designated hotel-apartments). Second, an experiment was designed to measure the effect of awareness-cards on Food Waste reduction through comparing the findings from the control and the experiment groups. The survey was conducted during the months of June, July and August, 2015, while the Food Waste experiment took place during the month of Ramadan, 2015. Some of the findings related the two research objectives are presented in the following graphs:
The Graph above clearly indicates the average amount of food-waste (FW) generated per guest per day throughout the experiment period of 20 days. The first day of the experiment for the Control Group, i.e. without awareness cards, the average amount of food waste started at 0.6 Kgs per person (i.e. guest), but reduced through the experiment period. For the experiment group when awareness cards were provided on tables the food waste remained very consistent at around 0.2 Kgs per guest. The overall results showed overwhelmingly that awareness, once generated has an immediate, clear and positive influence on customer behaviour, and in this case reduced the average food waste. The experiment measured total food-waste during the 20 days within this restaurant at 1,335 Kgs. Several important points constituted the conclusion and recommendations drawn from the results and analysis of both efforts. The summary highlights the vital importance and need for investments across all aspects of material recycling, which should be encouraged at a government level, and extended to SMEs, to develop local businesses within the recycling sector in Qatar. More efficiency is also required between F&B organisers and charities, and great incentives should be put in place for those participating in recycling efforts, and conversely penalties should be implemented for those organisations not actively pursuing “reduction” strategies to waste. Food cost reduction, without impact on food quality or perceived value, could be conservatively reduced by about 50% through spreading awareness of the impacts of Food Waste on the environment.
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Influence of Sinusoidal Drive Speed Modulation on Rotor with Continuous Stator Contact
Authors: Abdullah Alzibdeh, Mohamed Y. Al-Qaradawi and Balakumar BalachandranTorsional vibrations experienced by drill strings can be detrimental to drilling operations. With a goal of understanding torsional vibrations experienced by drill strings and determining means to attenuate undesired vibrations, the authors have studied the effect of adding a sinusoidal modulation to a constant rotation speed of a drill string. A combination of modeling, analysis, and experiments is used to explore the influence of this rotation input modulation on the system response. The drill string is modeled as a modified Jeffcott rotor, which is described by a system with three degrees of freedom. Considering the case of forward whirling of a rotor in continuous contact with a stator, the equations of motion are reduced to a single degree-of-freedom nonlinear oscillator describing the torsional motions. In order to understand the fast time scale and slow time scale components of the motion, the method of direct partitions of motions is used to determine an approximate response to the nonlinear oscillator. The obtained results of the analysis illustrate that with the sinusoidal modulation of the rotor drive speed, the equivalent torsion stiffness can be enhanced and the character of the friction force at the contact can be made smooth. The analyses helps bring forth the stabilizing influence of the added sinusoidal input to the rotor drive speed. Over the considered parameter ranges, the numerical results obtained with the full three degree-of-freedom model and the reduced single degree-of-freedom model are found to be in agreement with each other. Furthermore, the results from these models are found to compare well with those obtained by using the method of direct partition of motions. Experiments with a laboratory scale drill-string arrangement are to be carried out to validate the analytical and numerical findings and further explore the effectiveness of the drive speed modulation on the rotor dynamics.
Introduction
Slender rotating structures are used in many engineering applications. Drill strings are long rotating slender structures, which are used in drilling operations. A schematic of a rotary drill rig is shown in Fig. 1 (e.g., Liao, Balachandran, Karkoub, and Abdel-Magid, 2011). Drill strings experience different types of vibrations (axial, torsional, and lateral vibrations) that may lead to detrimental failures of a drilling system. Drill-string vibrations have attracted the attention of many researchers, and many models have been developed to understand them. Since drill strings have a large length-to-diameter ratio, typically, the first torsional natural frequency and first lateral natural frequency are close to each other. This frequency proximity and the nature of the system allows for coupling and energy transfer between the associated vibration modes. Here, as a step towards developing further understanding, a drill string is modeled as an extended planar Jeffcott rotor with gravity acting normal to the rotor. Due to the planar motions, no gyroscopic effects are considered. The extended model, which was earlier considered in the work of Vlajic, Liu, Karki, and Balachandran (2014), is shown in Fig. 2. The model is described with three degrees of freedom (DOF), namely, x and y to account for lateral motions, and theta to account for torsional motion. A large number of research efforts have focused on controlling drill-string vibrations by using different feedback control algorithms, which need measurements along the drill string. In this work, the authors propose a different control approach to mitigate whirling motions during continuous rotor-stator contact. This can be compared to a situation of a drill string being in continuous contact with the borehole. The approach is open loop in implementation and this approach is based on adding a high frequency input to the drive speed of the drill string. Given the open-loop nature, the method does not depend on any measurements along the drill string or rotary table, which could be attractive for a practical stand point. Although the current focus is on motions of a rotor with continuous stator contact, it is planned to study stick-slip and non-contact cases in the future.
System Modeling, Studies, and Results
As previously mentioned, the drill string is modelled as a Jeffcott rotor with three DOF. Proceeding along the lines of the group's prior work (Vlajic, Liu, Karki, and Balachandran, 2014), after some approximations for the continuous rotor-stator contact case, the 3 DOF system is reduced to a single second-order nonlinear differential equation governing the torsional motion. In Fig. 3, for a representative case with a constant drive speed, the torsional state histories obtained for the full model and the reduced model are plotted. It is noted that the final state of the motion is captured quite well. To further analyze the response during forward whirling, the reduced-order model was nondimensionalized and an approximate solution was obtained by using the method of direct partitions. This method allows one to separate slow scale motions from fast scale motions. As discussed, in the group's prior work, this method can be useful to examine whirling motions. The results obtained by directly integrating the full model as well as the reduced-order model have been compared with that obtained by using the method of direct partitions of motions. It is seen that the perturbation analyses is able to provide an approximate solution that compares well with the numerical results obtained through direct integrations. Next, this analysis is used to examine the influence of the addition of secondary frequency component. It is seen that the addition of the secondary frequency, a high-frequency one, helps smooth out the friction coefficient variation with respect to the relative speed at contact. This is found to have a beneficial effect on the motion and helps suppress large-amplitude torsional motions. Stability analysis was also conducted to examine this effect.
Concluding Remarks
A study has been conducted to examine the influence of sinusoidal modulation of rotor drive speed in a system, wherein the rotor experiences continuous stator contact. A single degree of-freedom reduced model is developed to study the torsion response and it is found that the addition of a high frequency input can be beneficial in attenuating rotor motions. This is believed to be useful for developing open-loop control schemes for attenuating forward whirling motions of drill strings. Results obtained from a lab scale experimental arrangement will be used to examine the effect of this drive speed modulation further and they will be reported in the conference presentation. Future studies could build on the current effort to examine cases of backward whirling. Acknowledgment: The authors would like to gratefully acknowledge the support received from the Qatar National Research Fund for NPRP Project 7-083-2-041, to pursue this collaborative work between the University of Maryland, College Park, MD, USA and Qatar University, Doha, Qatar.
References
1. Liao, C.-M., Balachandran, B., Karkoub, M., and Abdel-Magid, Y., Drill-String Dynamics: Reduced-Order Models and Experimental Studies, ASME Journal of Vibration and Acoustics, Vol. 133, 2011, pp. 041008-1-041008-8.
2. Vlajic, N., Liu, X., Karki, H., and Balachandran, B., Torsion Oscillations of a Rotor with Continuous Stator Contact, International Journal of Mechanical Sciences, Vol. 83, pp. 65 − 75, 2014.
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Azolla as a Feedstock for Bio-Refinery: Cultivation, Conversion and Application
Azolla is one of the world's fastest growing aquatic macrophytes, with a doubling time of only 2-5 days (Taghi-Ganji et al., 2005). It can be found on the surface of wetlands, ditches, ponds and rivers, native to the tropics, subtropics, and warm temperate regions of Africa, Asia, and the Americas (Costa et al., 2009) (Figure. 1). It has been intensively studied during the last few years for its potential uses as a green manure in rice fields, as a feed supplement for aquatic and terrestrial animals, as a human food, as medicine, as water purifier, as a biofertilizer, control of weeds and mosquitoes, to eradicate different metals, or to remove nitrogenous compounds from the water and the reduction of ammonia volatilization which accompanies the application of chemical nitrogen fertilizer. (Gregory, et al., 1997; Lumpkin, et al., 1980; Sadeghi, et al., 2013). Several other studies have also verified Azolla's potential as a biogas and hydrogen fuel source (Peters, 1976; Newton 1976, Van Hove, 1989).
These beneficial uses urged researchers to call it “green gold mine”. Seven extant Azolla species (A. filiculoides, A. caroliniana, A. mexicana, A. pinnata, A. nilotica, A. microphylla, A. rubra) are reported) Armstrong, 1998). Among the Azolla species, A. filiculoides is the only fern which is found in Anzali wetland, northern Iran (Sadeghi et al., 2012a, b; Sadeghi et al., 2013). A. Filiculoides also grows in southern South America, and western North America to Alaska. Also, it is on the US noxious weed list. Azolla has already covered about 50 percent of the 20,000 hectare Anzali wetlands. The overgrowth of Azolla is now considered as a serious issue in this unique ecosystem. Now, this useful plant is a harmful weed in water because it forms dense surface mats, interfering with boating, fishing, blocking irrigation channels and waterways and recreational activities as well as degrading water quality by reducing oxygen levels. It has been an increasing effort to maximize the beneficial properties and find new applications for that. So, Thermochemical conversion was applied on this biomass. Thermochemical processes depend on the relationship between heat and chemical action as a means of extracting and creating products and energy. Pyrolysis, gasification, and liquefaction which is conducted at a temperature of several hundred degrees Celsius are categorized in thermochemical processes. Currently, there are two principal processes for bio-oil production from biomass: pyrolysis and hydrothermal liquefaction (HTL). Besides biocrude oil as a liquid fuel, a special type of biochar which can be considered as an attractive byproduct was produced in HTL process. This carbonaceous material, which has received less attention can be potentially used for the removal of heavy metals contamination from wastewater (Liua, et al., 2009). The Cu at higher concentrations is a potentially toxic metal in the environment, mainly as the soluble form Cu2+. Obtained biochar from HTL of Azolla was used for Cu removal. The major concern in (HTL) is the high temperature and consequently high pressure of the process which results in high capital cost of equipment. So the process pressure and temperature should be reduced, but at a lower temperature, bio-oil yield is not high enough to make HTL economical for sustainable fuel production. For this purpose, ethanol was used as a solvent instead of water. Also, lipid extraction from Azolla was studied with Soxhlet extraction; because of its simplicity in operation, potential for scale up and safety. As our knowledge, to date, no study has reported an evaluation of the Azolla bio-refinery and also thermochemical conversion of Azolla for producing advanced fuel. This research was conducted in two parts: 1) cultivation and 2) conversion. The purpose of cultivation was to find the optimum requirements to reach the highest growth rate of Azolla under laboratory conditions. The results will help us to manage growing of this aquatic fern and also conserve wetland. This study showed, Humidity and pH are the most significant variables for achieving maximum Azolla growth rate. In conversion part; an all-out attempt was made to maximize the beneficial properties of the Azolla-Anabaena association and to find its new applications. After cultivation and harvesting of Azolla, this biomass was investigated as a feedstock for thermochemical conversion process. Lipid extraction, hydrothermal treatment, hydrothermal liquefaction and pyrolysis process were scrutinized aimed at utilizing Azolla as a biodiesel, liquid fertilizer, biocrude oil, biochar. Also, after these processes, liquid and solid residual were separated and analyzed for future utilization as liquid fertilizer and absorbent for heavy metal removal, respectively. This harmful weed with its fast growth rate and high potential products can be quite useful plant and can be fed into biorefinaries so that its removal will also conserve wetland. An all-out attempt has been made to maximize the beneficial properties of Azolla and find new applications for it. Reaching the highest growth rate under laboratory conditions will be conducive for managing this fast growing fern. Humidity and pH are the most significant variables for achieving a maximum Azolla growth rate. The dry mass growth rate of Azolla was. The maximum growing rate was achieved at; temperature: 22 °C, light = 20 Lux, humidity: 75% and pH = 6.4 with 2.1 days considered as doubling time. Lipid extraction, hydrothermal treatment, hydrothermal liquefaction and pyrolysis process were exerted upon Azolla for producing biodiesel, liquid fertilizer, biocrude oil, and biochar. Hydrous harvested Azolla converted to bio-crude oil at hydrothermal condition and Heat value increased from − 0.86 to 31.0 MJ/kg (yield = 39%). Bio-crude oil derived from pyrolysis had yields 29% with HHV = 33.2 MJ/kg. Pre-treatment at 180 °C before hydrothermal liquefaction at 300 °C was produced highest bio oil quality. Lipid content in Azolla was about 11.7%, which includes 38.07%, 39.49% and 19.81% saturated, monounsaturated and polyunsaturated fatty acids, respectively. The nitrogen rich liquid was produced at hydrothermal treatment. This harmful weed of overgrowth rate can be fed into biorefinaries so that its removal will also conserve wetlands.
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Advanced Multiphase CFD Modelling to Understand Impact of Undersea Oil Spill
Authors: Krishnaswamy Nandakumar, Abhijit Rao and Kalliat T. ValsarajThe growing energy demand across the globe has resulted in an increase in the deep water oil exploration activities which in turn has increased the risk of occurrence of associated accidental oil releases. Oil and Gas offshore businesses are important to Qatar's economy. Further, the country is heavily dependent on its marine water resources for fulfilling its potable water needs through the desalination process. So, it is imperative to safeguard the marine environment during an unfavorable accidental oil release, which essentially would put entire ecosystem into peril. Development of reliable models can assist in predicting the extent of damage caused to the environment and can further help in deciding the mitigating strategies during such events. The current research focusses on exploring the of capabilities of Multiphase Computational Fluid Dynamics (CFD) models in simulating various transport processes associated with deep water oil spills. The accidental release of oil in deep oceans results in formation of the plume. The interaction of inertial oil mass with surrounding water results in the formation of droplets which rises in the water column due to buoyancy. Dispersant addition is one of the preferred methods of oil spill remediation which causes the lowering of interfacial tension at the oil/water interface and under the action of local turbulence, it enhances the droplet disintegration process. In deep spill scenarios, droplets spend large amounts of time in the water column, hence, the dissolution process of soluble hydrocarbons which otherwise is detrimental to aquatic life, becomes important. The objective of this work is to develop integrated numerical models which can effectively guide us in predicting the fate of oil mass in such scenarios and help us is estimating the overall impact of such accidents on the environment. Before taking a leap into full scale modelling, it is imperative to grasp a good understanding of above mentioned transport processes at a more fundamental scale. Hence, in the first phase of this project, single droplet dynamics in quiescent systems were studied. We primarily investigated the effect of surfactant (the chief component of a dispersant), on the dynamics of a crude oil droplet rising in a stagnant column. Laboratory scale experiments were performed and a multiphase CFD model based on Volume of fluid method was developed to capture the shape dynamics of the droplet rising in a surfactant laden environment. To capture the subsurface dissolution of hydrocarbons from oil droplet, a unique experiment was devised wherein a binary organic mixture, representing a pseudo oil droplet comprising of volatile and non-volatile hydrocarbons, was employed to study the effect of unsteady mass transport on the overall dynamics of the droplet. Based on the experimental observations, correlations were proposed to estimate the mass transfer rate at various stages of droplet motion. A CFD model capable of evaluating concentration fields of the transported species in both dispersed as well as continuous phases, was developed by coupling VOF approach with species transport model. The above models were also employed to study the jet breakup dynamics in the laminar regime. The next challenge was to extend the applicability of developed models to large scale scenarios. Turbulence is inherent to oceanic environment and hence incorporating it into existing models becomes important. In a real deep spill scenario, a swarm of bubbles and droplets often interact with each other in a turbulent environment and this leads to occurrence of a sequence of coalescence and disintegration processes. The information on size of droplets serves as an important parameter for the evaluation of approximate rise velocities and overall mass transfer rates in the system. Thus, a model capable of predicting droplet size distribution can be employed for determining the fate of droplets in the event of accidental subsea releases. In current work, this objective was achieved by integrating traditional multiphase CFD models and turbulence models, with a population balance (PB) approach. The developed model was validated against the experimental observations reported in Johansen et al (Marine Pollution Bulletin. 2013;73(1), 327–335). Through this work, we were able to demonstrate the capability of an integrated CFD+PB model in analyzing the effect of dispersed (oil) phase flow rates, the presence of dispersants and the presence of air (introduced along with the dispersed phase) on the overall size distribution of oil droplets.
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Tremendous Change in Economy of Qatar Through Economics‘s Tools
More LessAs about Qatar well known country among Gulf countries, depends on a single commodity of resources or we can say rentire state which is totally depends on natural resources as petrochemicals and gas. In the classical views of economics always use the diminishing law of return in production, which shows if production factor one or two are used in production, this will increase production but in decreasing rate. Which means if factors of production are not using equally, this problem may come in production of anything but other things should same as technology etc but somewhere its work still in life. Qatar has an unemployment problem in youth, which could be solved through Government interference in the policies for example: Qatar and other Gulf States are suffering from lack of economic growth of the country. But to solve these problems, the Government sets up a central planning authority which has been called by several names, such as the planning commission, planning ministry or planning board. What goods should be produces, how should they be produces, how should they be distributed among the population and how much should be invested to bring about economic growth are all decided but the central planning authority. This method of solving central problems through the use of economic planning has been adopted in socialist countries. In such economic system, the capital and property are collectively owned by society and work of production is organized by the government. In this system, private entrepreneurs have no right to undertake the work of production and consumers lose their freedom to choose and consume the goods of their choice. Government plays an active role in the solution of the various central problems, regarding production, distribution and investment. Regarding Qatar, this policy works in international market as consumers of Gas is in world–wide. So the government of Qatar control its Gas production as not demand for and supply of Gas but the price will determine its production (as international market will give the price of Gas) Government of Qatar and of Corse other GCC countries could control its economy through the interference of the Government of the country. As the adaptation of proper monetary policy (in which the policies regarding the supply of money, bank credit and the rate of interest are included), fiscal policy (which is concerned with the government expenditure and taxation policies) and direct controls such as industrial licensing policies, control on price, import and exports. The other economic tool could be used in production of a single commodity as LNG in Qatar. Production possibility Curve in economics explains how much production of gas should be optimum level of production. One of the major issues before the oil-rich Gulf States (Qatar) in recent decades has been the diversification of their economies from the oil to non-oil sectors. Their heavy dependence (from 70 to 90%) on the oil revenues has prompted these countries to formulate the policies so that other sources of income from the non-oil sector can be enhanced. But the question is how in these Gulf States have been successful in implementing these policies? Moreover, what are the major drawbacks in the diversification their economies in the present time? In this paper, an attempt has been made to understand the rationale behind the diversification of Arab Gulf economies dominated any single rent revenues. This has been discussed in the framework of their overall macro-economic development, taking into consideration the various factors of productions, so that a desired balanced growth can be maintained. The main focus of the paper is on the current initiatives taken these States towards the building of a non-oil economy. While highlighting the Arab Gulf State's economic diversification drive, the paper, particularly point out the varying degrees of seriousness and success because as this paper concludes, this economic diversification project cannot be conceived without taking into account the impact of fluctuation in oil prices in the global market as well as on the overall economic and political stability in the region.
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Enhanced Energy Extraction from a Solar Panel
Authors: Shahbaz Tabish, Atif Iqbal, Imtiaz Ashraf and Khaliqur RahmanDue the movement of the sun throughout the day, the insolation level incident on the fixed panel surface varies largely. The maximum level of insolation occurs only around noon. This leads to the panel to be under-utilised. To maximise the utilisation of the panel during the day, mechanical solar tracking is used. This method not only increases the utilisation of the, but increases the power being extracted from the panel. Solar tracking using one axis tracking increases the energy yield from the solar panel by 40 percent.
Extended Abstract
During the span of a day the sun's movement has been shown in figure 1. As the day passes by, the level of incident solar radiation (insolation) changes. This change takes place due to position of the sun. The angle at which the sun's rays fall on the photovoltaic panel affects the insolation level available for the panel to convert into electrical energy. For the fixed panel, the sun's rays are not normal to plane of the panel most of the time. This causes the panel to be under-utilised. To extract more energy from the same panel, solar tracking is required. This follows the sun's movement thereby increasing the insolation level throughout the day. This increase in the insolation level is due to the fact that the angle between the normal to the solar panel and incident light is to be kept minimum.
Figure 1: Sun's movement throughout the day
The principle of a single axis solar tracking has been shown in figure 2. The solar tracking can be accomplished by four methods: active tracking, passive tracking, chronological tracking and manual tracking [1]. Active trackers measure the light intensity from the sun using light sensors which give signal to the controller and driving mechanism. Passive trackers commonly make use of a low boiling point compressed gas. This gas is filled in two canisters each placed in east and west directions. The heating of the fluids cause the panel to tilt over to the side with more sunshine. These will have viscous dampers to prevent excessive motion in response to wind gusts [2]. A chronological tracker uses a rotation mechanism to counteract the effect of Earth's rotation. A simple rotation mechanism, turning at a constant speed of one revolution per day or 15 degrees per hour, is adequate for many purposes, such as keeping a photovoltaic panel pointing within a few degrees of the Sun. This can easily be achieved by the use of a stepper motor control.
Figure 2: Principle of single axis solar tracking
The data for the insolation level and temperature for the whole year have been obtained from the NASA website for Aligarh and Doha [3]. The simulations have been run assuming that there is no condition of partial shading. For the purpose of simulation of energy output during the day, five solar panels of 250 Wp were taken in parallel to give a total of 1.25 kWp of power under STC. The energy outputs for the months throughout the year were obtained for two conditions: first for the fixed panel condition, and second for the panel with continuous one-axis solar tracking. The results have been compared and shown for Aligarh and Doha in Figs. 3 and 4 respectively. In Fig. 5, the percentage increase in the energy output for each month has been shown for both the cities.
Figure 3: Daily energy yield from a 1.25 kWp solar array on a monthly basis in Aligarh
Figure 4: Daily energy yield from a 1.25 kWp solar array on a monthly basis in Doha
Figure 5: Increase in daily energy yield on a monthly basis
References
[1] B H Khan ‘Non-Conventional Energy Resources’ Tata McGraw Hill, 2009.
[2] Kamala J. and Alex J., 2014, ‘Solar Tracking for Maximum and Economic Energy Harvesting’, Int. J. of Engg. and Tech, Vol. 5(6), pp 5030–5037.
[3] NASA Surface meteorology and Solar Energy website: https://eosweb.larc.nasa.gov
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Isolation and Identification of Potentially Pathogenic Vibrio Species from Qatari Coastal Seawaters
The genus Vibrio accounts for a major group of marine and estuarine bacteria capable of causing diseases in various aquatic organisms including fishes, corals, shellfish's and shrimps. Infections with these organisms have profound environmental and economic consequences. In the present study, 52 isolates of Vibrio species were isolated from the water samples collected from 14 sites surrounding Qatar during the winter season. Using 16S rRNA gene sequence analysis and MALDI-TOF MS we identified 13 different luminous and non-luminous Vibrio species. V. alginolyticus (50%) was the predominant species followed by V. harveyi (11%), V. owensii (7%), V. nigripulchritudo (6%), V. rotiferianus (6%), V. mediterranei (6%), V. hepatarius (2%), V. shilonii (2%), V. maritimus (2%), V. coralliilyticus (2%), V. tubiashii (2%), V. parahaemolyticus (2%), and V. proteolyticus (2%). We were able to identify all (100%) isolates using 16S rRNA, (>94 percentage similarity) as compared to MALDI TOF-MS which could correctly identify only 60% isolates. Majority (70%) of the potentially pathogenic Vibrio's isolates of Vibrio's were recovered from the fishing ports of Qatar namely Al-Khor and Al-Wakra. The isolation of various pathogenic species of Vibrio's from the Qatari marine environment indicates the potential sanitary risk and stresses the need for further studies to prevent infections.
Acknowledgments:
This research was supported by the research grant (Grant NPRP 6-647-1-127) from the Qatar National Research Fund (a member of Qatar Foundation) to R. Fotedar (Ministry of Environment, Qatar), Thorsten Stoeck (L, Germany), Teun Boekhout (CBS- KNAW, The Netherlands) and Jack Fell (RSMAS,USA).
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Performance Analysis of Multiphase High Power Open End Drives Fed from Dual Matrix Converter
Authors: Khaliqur Rahman, Atif Iqbal, Nasir Al-Emadi and Rashid Al-AmmariIn this paper an open ended seven phase stator winding drive is considered for analysis that is to be fed from matrix converter controlled by space vector pulse width modulation scheme. Open-end winding variable speed drives with dual matrix converter supply have been extensively investigated for various applications in the past, based on a three-phase machine configuration. This topology is relatively simple for practical realization. It offers a higher number of switching states without the need for capacitor voltage balancing algorithms, when compared to the equivalent standard multi-level converter in single sided supply mode. This paper considers a seven-phase open-end winding topology. A relatively simple SVM algorithm, based on already developed seven-phase two level drive SVM method, is used for operation of both converters. The proposed modulation technique is straight forward to implement and is capable of generating pure sinusoidal output voltages, without any low-order harmonic components. The method offers superior harmonic performance when compared to seven-phase topology in single-sided supply mode. The developed scheme is verified by simulation, using a seven phase induction machine operated under V/f control. The proposed drive topology find application in high power ac drives such as in oil & gas industries, electric/hybrid electric vehicles, ship propulsion, traction etc. The simulation results support the proposed idea.
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Modeling Development of a Combined Methane Fixed Bed Reactor Reformer
The growing concern of many countries globally about the greenhouse gas emissions have emphasized interest towards dry reforming of methane (DRM). For an oil and gas based economy such as the state of Qatar, CO2 emission is a big challenge, as it has rendered Qatar as the highest CO2 emitting country per capita in the world. The potential of DRM process for integration in the existing infrastructure of Qatar is a key aspect of this research as a part of exceptional proposal granted to Dr. Nimir Elbashir by QNRF aimed at CO2 fixation. DRM is a heterogeneous chemical reaction in which the two greenhouse gases; CH4 and CO2 are converted to synthesis gas. Synthesis gas or ‘syngas’ is a precursor to a large variety of value added chemicals including hydrocarbons via Fischer-Tropsch Synthesis (FTS). In addition to CO2, steam can also be used to reform methane into syngas in a process known as steam reforming of methane (SRM). Steam Reforming of Methane (SRM) ΔH298 = 206 kJ/mol (1) Dry Reforming of Methane (DRM) ΔH298 = 247 kJ/mol (2) In addition to these two processes, there is also an exothermic reforming process, known as the partial oxidation of methane (POX), where methane is combusted to yield syngas. DRM process is beset by numerous major process limitations including its high endothermicity, high rate of catalyst deactivation (due to carbon formation) and low-quality syngas yield ratio (H2:CO⇐1:1). These challenges have posed severe obstruction towards widespread commercialization of this technique. A synergistic amalgamation of the reforming of methane as DRM+SRM, DRM+POX and DRM+SRM+POX have been recommended in the literature as a way to tackle the intrinsic limitations of the DRM process. In the current work, such combinations of methane reforming processes have been simulated thermodynamically using direct Gibbs free energy (GFE) minimization method. Energy valuations of various case scenarios have been carried out under varying operating conditions (temperature, presssure and feed mole ratios) assuming both ideal gas conditions and non ideal regimes using cubic equations of state (Peng Robinson (PR), Redlich Kwong (RK) and Soave Redlich Kwong). The main objective of the thermodynamics aspect of this study is to find optimized condition of reduced energy requirement and reduced carbon deposition while maintaining considerable CO2 fixation in a combined reforming process. In order to completely understand the system, a one-dimensional pseudo-homogeneous fixed bed reactor model which incorporates all the transport limitations (heat, mass and momentum) for combined SRM/DRM processes is developed. Reaction kinetics utilizing Langmuir-Hinshelwood Hougen-Watson (LHHW) type rate expressions published in the literature for SRM and DRM under analogous operating conditions have been used in the reactor bed model. These model results will be further validated against the experimental data published in literature. The kinetic conversion profiles are then compared with the thermodynamic results to systematically determine the regimes of kinetic deviation (from equilibrium) for the combined SRM/DRM system. This approach of carrying out both thermodynamic and reaction engineering analysis is advantageous in understanding the reforming process in a broader view and will also help in setting base for experimental investigations. These modeling results will be used as pre-experimental initial findings for the NPRP exceptional project aimed towards development of highly effective and coke resistant catalysts.
References
Pakhare, D. and J. Spivey, A review of dry (CO2) reforming of methane over noble metal catalysts. Chemical Society Reviews, 2014. 43(22): p. 7813-7837.
Song, C., Tri-reforming: a new process for reducing CO2 emissions. Chemical Innovation, 2001. 31: p. 21-26.
Jiang H, Li H, Zhang Y., Tri-reforming of methane to syngas over Ni/Al2O3—thermal distribution in the catalyst bed. Journal of Fuel Chemistry and Technology 2007. 35: p. 72-78.
Noureldin, M.M.B., N.O. Elbashir, and M.M. El-Halwagi, Optimization and Selection of Reforming Approaches for Syngas Generation from Natural/Shale Gas. Industrial & Engineering Chemistry Research, 2014. 53(5): p. 1841-1855.
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Analysis of Sand Bacteriophages Genome in Qatar
Authors: Umm-Kulthum Ismail Umlai, Annette Shoba Vincent and Valentin IlyinAbstract Objective: In this era of increasing antibiotic resistance (WHO)[1], we are running out of time as common bacterial infections are progressively rejecting drugs that would be standard for treatment. It is due to these reasons that research regarding bacteriophages, viruses that infect bacteria has seen a sudden revival. The Science Education Alliance- Phage Hunters Advancing Genomics and Evolutionary Science (SEA-PHAGES) headed by Dr. Graham Hatful from the Howard Hughes Medical Institute (HHMI)[2], University of Pittsburgh and Carnegie Mellon University has begun a nationwide initiative to discover, categorize and study the billions of bacteriophages that surround us. This initiative aims to create a thorough database containing genomic data for as many bacteriophages as possible. The study of these viruses is virtually new, and thus requires a significant effort; there is a novel, virtually untapped resource of genes and proteins that could greatly benefit our understanding of genomes and be used as treatments to bacterial infections that are resistant to antibiotics. Studying the bacteriophages is of great importance. The same protocols and procedures from the SEA-PHAGES program were applied to search for bacteriophages in Qatar within the sand and soil at Carnegie Mellon University Qatar. This is the first research of its kind to be carried out in Qatar and possibly at the Gulf region. Bacteriophages, which infect Arthrobacter.sp, were discovered in the sand from Al-Rayyan, Doha Qatar (Diversity of Bacteriophages in the ecology of Qatar). Following this, the viral plaques obtained were purified, isolated using a QIAamp MinElute Virus Kit[3] (Qiagen) and finally sequenced using Next Generation sequencing methods at Weil Cornell Medical University Qatar. Method: The sequenced DNA of phages were assembled using a Short Oligonucleotide Analysis Package- Denovo (SOAP-Denovo) software package. A program called Velvet has been also used in conjunction to ensure the best results were obtained using the optimal k-mer, providing the longest contig length. The longest length obtained was a contig of 12,380 at a k-mer of 59, along with a large number of smaller contigs. The largest 201 contigs have been annotated; gene nucleotide and protein sequences were collected, using the gene prediction software, GeneMarkS available online. Each of the genes from the contigs were then searched against the entire non redundant protein (NR) database of available annotated genes at the National Centre for Biotechnology Information (NCBI's) online database using Basic Local Alignment Search Tool (BLAST-p). They were also searched against non-submitted phage genomes collected at SEA-PHAGES. That result in about 558 annotated genes/proteins. All the proteins are being studied to understand better what the bacteriophage genome comprises of and how the proteins allow them to survive and infect bacteria in the sand collected from Al Rayyan in Doha. Results: So far three different bacteriophage contigs were found from the sequenced DNA, containing a total of 14 genes, most of which are derived from the Enterobacteriophage T7 cluster. However the individual genes displayed some variation from the original genes due to the small rate of mutations that naturally occurs with bacteriophages during replication. In addition to this, variations could be due to natural exchange of genetic information between viruses to form mosaic genomes. Thus each bacteriophage is unique due to this variation and each has proteins that can perform a slightly different function. One such gene was found had a 99% identity with Gene 3.5 from the Enterobacteriophage T7 family (phages that can infect Escherichia coli (E.coli) bacteria, which are commonly responsible for foodborne illnesses). This particular gene was searched against the PDB (protein database) from the same NCBI BLAST tool, to search for mutations. The query returned results of 100% identity with a (Chain L) T7 RNA Polymerase complexed with T7 lysozyme (interplay between an RNA polymerase and lysozyme). One particular bacteriophage contains a gene originating from a bacteriophage of the Yersinia species (phiA1122). This gene codes for a head-to-tail joining protein, which is a major component of a phage. This bacteriophage principally infects and neutralizes, Yersinia pestis, which is the causative agent of the Bubonic plague in humans[4] (Garcio.E). This particular gene must have been transferred during naturally occurring gene exchange between bacteriophages that infect the same organism simultaneously (Fleischmann, W) [5]. Discussion: The findings strongly suggest that Gene 3.5 has a function in breaking down the bacterial cell wall during infection. A further search on the Research Collaboratory for Structural Bioinformatics (RSCB) PDB was carried out to find a structural view of the protein. Upon studying the protein, it was found that the fragment containing the mutation is not seen in the crystal structure, which means it is a flexible loop. If this section of the protein moves in the crystal structure then it most probably moves in nature as well. This strongly suggests that the flexible mutated loop on the protein surface could affect of protein-protein interaction; and may result in slight changes in the mechanism (or temperature) by which the phage ligates or transfers genetic information from one phage to another. Future work: Future work aims to further study the Qatari bacteriophage genes and their proteins, their mutations and functions. Characterizing the remainder of the bacteriophage will allow us to better understand and annotate its genome. The relevance of these phages in a practical application could be in medical, industrial or agricultural uses. It could possibly have a role in treating E.coli infections or to prevent the contamination of such bacteria in the food industry. Further research could be done to sample more sand from various parts of Qatar (and various depths within the sand) to search for more bacteriophages. It is very likely that there are bacteriophages that could have more significant applications present within the sand. The same procedures could be followed to determine the functions and the nature of these phage genes.
References
[1] World Health Organization. 2015. Antimicrobial Resistance. Available at: http://www.who.int/mediacentre/factsheets/fs194/en/. Accessed on 13 November 2015.
[2] Howard Hughes Medical Institute. Science Education Alliance. Available at: http://www.hhmi.org/programs/science-education-alliance. Accessed on 13 November 2015.
[3] Qiagen.com. 2015. QIAamp MinElute Virus Kit. Available at: https://www.qiagen.com/us/shop/sample-technologies/combined-sample-technologies/preparation/qiaamp-minelute-virus-spin-kit/. Accessed on 13 November 2015.
[4] Garcio.E. 2003. The Genome Sequence of Yersinia pestis Bacteriophage φA1122 Reveals an Intimate History with the Coliphage T3 and T7 Genomes. Journal of Bacteriology. [Online]. Available at: http://jb.asm.org/content/185/17/5248.full. Accessed on 13 November 2015.
[5] Fleischmann. W.R. 1996. Chapter 43: Viral Genetics. Medical Microbiology 4th edition. Available at: http://www.ncbi.nlm.nih.gov/books/NBK8439/. Accessed on 13 November 2015.
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Chemical Characterization and Source Identification of Beached Oil from Two Areas Along the North-Western Coast of Qatar
Authors: Nasser Alkaabi, Mohammad Alghouti, Nabil Zouari, Theis Solling, Steffen Bach and Jan H. ChristensenOver the years there have been several reports of oil spills affecting particularly the northern coast of Qatar. In most cases, the source of oil spills is not identified. The spilled oils are very resistant to degradation and can affect the coastal ecosystem over many years. Even today, after 24 years, some of the oil that was spilled during the 1991 Gulf War can be found in sand, close to the Al Zubahra UNESCO site.
The Maersk Oil Research and Technology Center in Doha (MO-RTC) has established the Oil Fingerprint project in collaboration with the University of Qatar and the University of Copenhagen. One of the objectives of the collaboration is to identify the potential source and origin of oil spills based on their chemical composition.
A total of 38 samples were collected. During the sampling campaign it was discovered that the coast was contaminated with highly weathered oil that could originate from the Gulf War era but also with more fresh oil that most likely originates from recent oil spills in the Arabian Gulf. We therefore collected polluted soil samples and contaminated sediments from two main areas along the beach in North-western Qatar. The samples were analysed using gas chromatography – mass spectrometry in selected ion monitoring mode (GC-MS/SIM) and the oil composition was characterized. The likely source of the beached oil was identified by a comparison of diagnostic source ratios by comparing petroleum hydrocarbon fingerprints of steranes and hopanes of the spills against an oil database. The initial chemical fingerprinting based on selected ion chromatograms (SICs) of steranes (m/z 217) and hopanes (m/z 191), were remarkable similar as were the C29-/C30-Hopane ratios between sampling sites. However, a more detailed pixel-based analysis showed significant differences between samples.
The process also included an assessment of the physical and biological weathering effects on the oil spills. Petroleum biomarker patterns (steranes and hopanes) are identical for all 14 samples included in this pilot study. The only differences observed were in the relative concentration of LMW and HMW steranes. This could be due to real source oil differences, however, the general weathering patterns indicate that these differences are more likely due to extensive weathering of especially two samples (9-02, 3-02) but also 8-01 and 10-01 shows severe weathering effects. Analysis of alkyl-PAHs provided an overall evaporative weathering degree for the samples. Distinct differences in the isomer patterns were observed for 3- to 4-ring alkyl-PAHs and this cannot be immediately explained as biodegradation. The largest fraction of the samples seems to originate from the same source but other sources are clearly present. A more detailed analysis with normalization to Euclidean norms within six selected SICs revealed more source specific information. In conclusion, the results indicate at least 2-3 different sources on the basis of differences in PAH isomer patterns. This was confirmed by visual inspection of SICs of C1-C3 alkyl-substituted phenanthrene, dibenzothophene, chrysene and pyrene isomers. Apart from the finding that the spills originate from several sources, the evaporation profiles indicated that not all of the spills are crude oils but that some are also heavy fuels. This suggests ongoing bunker flush off the coast of Qatar.
These findings are of importance in further bioremediation processes in which, different approaches should be investigated to achieve high efficiency strategies if removal of oil pollutants from AlZubaraa area.
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Remarkable Thermal Stability of Nano-Crystalline Al-Mg-Li Alloys through the Addition of 1%Sr
Authors: Sara Iyad Ahmad and Khaled YoussefNanocrystalline metals -with grain sizes less than 100 nm- have proven to attain exceptional mechanical properties such as strengths that exceed those of coarse-grained and alloyed metals with grain size greater than 1 μm. As a result, such materials are to be acknowledged as the new class of high-performance engineering materials and to be implemented in various structural applications. The main reason behind the ultrahigh strength of this class of materials is mainly grain refinement, as in this mechanism, reducing grain size means introducing more grain boundaries. Grain boundaries act as barriers to the intra-grain dislocation motion, which is the main cause for the ductility of materials. Hence in its absence, the material is said to be strong and hard to deform. However, the strength associated with the new reduced grain size is associated with a penalty that leads to microstructural instabilities. This is because the atoms that lie in the grain boundary region are not as ordered and stabile as inside the grains. Hence those atoms are occupying unfavorable interfacial positions energetic wise, which means that they have high energy. As a result of the high volume fraction of grain boundaries, the system tends to pursue stabilization by seeking a configuration that shall allow for the lowest energy possible. The atomic system tends to eliminate the root of the problem which is the large number of grain boundaries and solve the problem by grain growth. Thus the removal of grain boundaries becomes the driving force to decreasing the system's energy. Hence an obstacle is yet to be overcome in order for those materials to be fully utilized to the maximum, as those nano-materials are prone to grain growth at lower temperatures than their conventional counterparts, which limits their service temperatures and expected lifetime. Grain growth can be slowed or even eliminated either thermodynamically, for example by adding solute atoms that segregate to the high energy sites in the grain boundaries, occupying it and lowering the free energy of the grain boundaries, or kinetically by the presence of second phase particles which results in grain boundary pinning, reducing the mobility of the grain boundaries and hence grain growth. This research aimed to studying the effect of adding 1% strontium (Sr) on stabilizing the grain boundaries of an aluminum-based alloy (Al-Mg-Li) which has a very low density yet a specific strength higher than that of steel. In order to achieve the goals of this research, a comparison must be made between the two samples of Al-5Mg-4Li and Al-5Mg-4Li-1Sr. Samples were prepared in a SPEX 8000 shaker mill and annealed at various temperatures up to 600 °C. To study the effect of Sr under various thermal conditions, both the as milled and annealed samples were analyzed using various experimental characterization methods such as X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) to perform a structural analysis and calculate the grain size of each sample. Using the Williamson-Hall model to calculate the average grain size for both samples based on the obtained XRD patterns, the results showed that for the as milled samples of Al-5Mg-4Li and Al-5Mg-4Li-1Sr, the average grain size was calculated to be 36.59 nm and 25.86 nm, respectively. The previous results were further proven when the TEM average grain size calculations gave similar results of 33 nm and 21 nm for the as-milled Al-5Mg-4Li and Al-5Mg-4Li-1Sr samples respectively. The thermal stability of the samples was proven when the grain size was measured after annealing at different temperatures for both Al-5Mg-4Li and Al-5Mg-4Li-1Sr samples. The average grain size was measured for Al-5Mg-4Li (annealed at 400 °C) and Al-5Mg-4Li-1Sr (annealed at 600 °C) to be 172.05 nm and 38.90 nm respectively. This shows that even at a higher temperature, the grain size for the sample that has Sr is much smaller and is still the nano-range. To verify the previous results of thermal stability, Vickers-hardness was measured for each sample after annealing as the mechanical properties of the thermally stabilized sample is expected to exceed those of the conventional sized sample. The plot of hardness variation of the nanocrystalline samples as a function of annealing temperatures showed that at room temperature, the hardness values for Al-5Mg-4Li and Al-5Mg-4Li-1Sr samples were 2.85 GPa and 3.24 GPa, respectively. With increasing annealing temperature, the hardness of Al-5Mg-4Li decreases gradually and reaches a low value of 0.8 GPa after annealing at 600 °C. In contrast, Al-5Mg-4Li-1Sr showed excellent thermal stabilization with increasing annealing temperature. Increasing the annealing temperature to 600 °C decreased the hardness value to 2.73 GPa. This hardness value is almost as high as the hardness of the as milled Al-5Mg-4Li (2.85 GPa) at room temperature. Since the XRD patterns did not show any traces of second phase particles, we suggest that the stabilization of the grain size and hence other mechanical properties such as hardness at high temperatures can be attributed to solute drag or the thermodynamic mechanism. Grain Growth does not only limit the nano-crystalline materials service temperatures, but also its unique technological applications as a consequence. Hence we anticipate that the results of this research will have implications in the development of thermally stabilized ultra-tough nanostructured materials for technological applications.
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Diatoms & Dinoflagellates Associated with Seagrasses, Algae and Mangrove
Authors: Mohanad Mushtaha, Yousef Ashraf Nasr and Abdullrahman Al-MuftahMarine environments sustain a variety of living organisms starting from microorganisms up to large macro-organisms. This support comes with the diversity of marine habitats that are created naturally to provide certain conditions for each single organism. However, Mangrove areas are one of many important places that are considered to be highly productive and could be suitable for planktonic life. Mangroves can be defined as salt tolerant plants that grow on the coasts and in shallow water. There are many types of plankton such as Diatoms & Dinoflagellate (Phytoplankton) that may be found in Mangrove areas (N. M. Nour El-Din & J. A. Al-Khayat, 2005). The presence of Diatoms & Dinoflagellate could be related to the occurrence of floating detritus in which Diatoms & Dinoflagellate can be found in association with them (Faust, M., & Gulledge, R. 1995). Moreover, Planktons can also be found attached to the seagrasses and Algae along the shallow shorelines. The presence of such planktonic type is affected by temperature and salinity so; such floating environments will be used to examine this effectiveness at shallow mangrove areas and along the coast area. Mangroves, Algae and seagrasses are found sometimes suspended in the water column and they start to move up and down due to the generation of Oxygen bubbles. (Faust, M. & Gulledge, R. 1995). Because of that, we will collect them only at the daytime. Thus, we will look at the species composition and how they will be affected by the variation of temperature and light in different seasons (summer (2015), spring and fall) and identifying any invasive species. Samples will be collected from three coastlines around Qatar (Al-Thakiera, Fwiret and Al-Wakra) and will be observed using light and electron microscope. The importance of this study is to show and identify benthic diatoms and dinoflagellates species and to have data about the harmful types because they affect fish stocks and water quality, in order to avoid having these two main problems on Qatari waters.
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Synthesis and Properties of Nanocrystalline BiTe-Base Thermoelectric Materials for Energy Applications
More LessThermoelectric (TE) is the science associated with converting the thermal energy into electricity based on the Seebeck effect. The attractive features of thermoelectric devices are their long life, low maintenance, highly reliable and they do not produce emissions harmful to the environment. Thermoelectric generators are used to provide electrical power in medical, military, and space applications where their desirable properties outweigh their relatively high cost and low operating efficiency. However, the widespread use of thermoelectric components is presently limited by the low figure-of-merit of presently known materials. Bismuth telluride Bi2Te3 (which has a peak ZT value of 1.1) is currently regarded as the state-of-the art TE material with high efficiency and is therefore attractive for energy harvesting processes. The objective of the work is to demonstrate a new route to the realization of highly efficient bulk Bi2Te3 structures at the nanoscale. Nanostructures provide a chance to disconnect the linkage between thermal and electrical transport by introducing some new scattering mechanisms. This will help in increasing figure of merit and then the efficiency. We present in this work novel versions of both p-type and n-type Bi2Te3 alloy materials with significantly enhanced figures of merit (ZT) between 25 °C and 125 °C.
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Improving Water and Nutrient Use Efficiency for Crop Production in Dry Lands via Soil Amendments and Remote Sensing Techniques
More LessThe soils of the Arabian Peninsula in general and GCC countries in specific are dominantly sandy (low nutrient and water holding capacity, high infiltration rate). These soils need high inputs for crop production. To be cost-effective in agriculture production these soils need careful consideration to enhance water and nutrient use efficiency and increase crop production. A number of organic and inorganic amendments have been used by various researchers in this regards. However, little has been done in this respect on UAE soils, and hence forms the focus of this study. The study aims to achieve this through soil improvement using soil amendments and assessing the efficiency through remote sensing techniques.
The green house and field trials were conducted simultaneously (January 2015) on Okra (Abelmoschus esculentus) at ICBA station using sandy soil which is dominant in the UAE and the GCC countries. Five inorganic amendments (Zeoplant, Zeoplant pellet, Meliorit, AustaHort and Palagonite) and one organic (locally produced compost) were used at different rates (0, 1.5, 3 and 4.5 kg/m2). Fresh water is used to offset the irrigation requirement of Okra equivalent to 100% and 75% ETc. The treatments were triplicated in a randomized complete block design.
Agronomic parameters (Germination, growth, flowering and fruiting) were recorded. Spectral signatures were collected in the range of 400 to 1100 nm using a hand held spectroradiometer with standardized viewing and radiation conditions for all treatments. Each parcel was monitored spectrally from the stage of being a bare parcel to the stage of 50% covered by vegetation.
Okra fruit is collected on a weekly basis and weight recorded. The SPAD meter is used in the field and greenhouse for the measurement of chlorophyll content during the growth stages.
The organic and inorganic amendments in general improved the water use efficiency as well as enhanced the biomass production to a significant extent compared to the treatment where amendments were not used. At 75% ETc the performance of amended soils was comparable to 100% ETc and fruit biomass production was similar. The use of the soil amendments can save up to 25% of the irrigation water in sandy soils.
These are preliminary results from sandy soil representing the main soil type in UAE. These amendments may behave differently in other types of soils hence further test are being started in Arabian Gulf University to test the same amendments on Bahraini soil.
Keywords
Water scarcity, Crop production, Sandy soils, Water and Nutrient Use Efficiency, Monitoring efficiency, UAE
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Textile-Reinforced Mortar (TRM) System as a Strengthening Technique on Reinforced Concrete Beams
Authors: Muhammad Shekaib Afzal, Usama Ebead and Kshitij ShresthaThere is considerable investment in construction industry in Qatar for civil infrastructures and taking into account the severe environmental conditions, they would entail for proper maintenance, repair and strengthening for safe, continuous, uninterrupted, and efficient functionality. Reinforced concrete (RC) structural members, which constitute majority of construction works in Qatar, can be easily deteriorated by the deleterious effect of seawater exposure in the form of humidity or direct splashing for sea-level and offshore structures. Such deterioration can also be due to the exposure to extreme high temperatures, severe humidity and high chloride. All such environmental effect can significantly reduce the life-span of RC structures by up to 10-15 years.
The cost of rehabilitation and strengthening is usually estimated in millions of dollars. Traditional methods of strengthening corrosion-damaged structures involve the replacement of the corroded bars and the substitution of deteriorated concrete layers with new concrete. Our study proposes an “optimum strengthening technique” for RC structures to mitigate the prevailing conditions of Qatar. This relatively new technique utilizes “textile-reinforced mortar (TRM)” to strengthen concrete beams. TRM systems consist of one or more layers of textiles made of carbon, glass, or Polyparaphenylene benzobisoxazole (PBO) grids that are sandwiched between layers of associated cementitious mortars. The cement-based mortar used in TRM acts as a barrier against chloride ions penetration thus protecting the main reinforcing bars from corrosion attack. Textiles' lightweight, high tensile strength, corrosion resistance, and ease of application make the strengthening system appealing. The potential of TRM for the repair and strengthening of concrete structures is not just the result of its physio-mechanical performance but also the ease and simplicity of installation that does not require any sophisticated equipment or retraining of the construction work. In addition, the compatibility between the mortar used and the concrete substrate is inherited since both materials have the cement as a common “base”. TRM systems, with their innovative features, ensure the endurance of the rehabilitation process and consequently the sustainability of the strengthened structure.
Recently in the last few years, several research works in the USA and Europe in the field of TRM strengthening technique have been reported for masonry and concrete structural members. Majority of these works is limited to single type of textile (either carbon, PBO or glass) and on limited types of reinforcement levels. The work presented here compares two different types of TRM systems in the same domain, performed on three different levels of reinforcement ratios representing flexural deficient, lightly reinforced and typical under-reinforced beams.
Experimental works were done to state the efficiency and effectiveness of textile reinforced mortar (TRM) in increasing the ductility and the flexural capacity of reinforced concrete (RC) beams. The aim of the experimental work was to investigate the parameters that contribute to the increase in the load carrying capacity of beams strengthened with TRM system. Eighteen medium-scale rectangular RC beam specimens, 2500 mm long, 150 mm wide and 260 mm deep, were prepared at three different reinforcement ratios of “ “ρ” _“s” ^“1” “ = 0.5%;” o “ρ” _“s” ^“2” “ = 0.72%;” f: “ρ” _“s” ^“1” “ = 0.5%; “ “ρ” _“s” ^“2” “ = 0.72%; “ “ρ” _“s” ^“3” “ = 1.27%.” The strengthened beams utilized two TRM types namely carbon and Polyparaphenylene benzobisoxazole (PBO) TRM systems respectively. The RC beam specimens were tested in flexure under four point loading until failure with a clear span of 2.2 m. The strengthening technique was applied to the soffit of the beam (flat type) altering the number of layers of textile. Three beams (of three different reinforcement ratios) without TRM strengthening were used as control specimens. Nine beams were externally reinforced by one (“ρ” _“T-c” ^“1” “ = 0.014%”), two (“ρ” _“T-c” ^“2” “ = 0.028%”) and three (“ρ” _“T-c” ^“3” “ = 0.041%”) layers of carbon TRM system. Six beams were strengthened with one (“ρ” _“T-PBO” ^“1” “ = 0.009%”) and two (“ρ” _“T-PBO” ^“2” “ = 0.018%”) layers of PBO TRM system.
From Based on the experimental observations, a reasonable gain in flexural strength and energy absorption was achieved for both the TRM systems. An increase of the initial stiffness was achieved for strengthened specimens; however, an apparent decrease in the overall ductility was observed with TRM strengthening. Results showed that the flexural capacity of strengthened beams increased to an average of 38% for carbon TRM system and an average of 26.7% for PBO TRM system over that of their control (un-strengthened) specimens. The highest increase in the load carrying capacity was 77.51% for a specimen having with the main reinforcement ratio of D12 (“ρ” _“s” ^“2” “ = 0.72%)” and was strengthened with carbon TRM system using three layers of carbon textile.
Ductility index (ΔI) and energy absorption (Ψ) values were also calculated in order to know the behavior of ductility and flexural capacity in each of the beam specimen. The term ductility index (ΔI) is defined as the ratio between the deflection at the ultimate load and that at yield load, representing its ability to stretch/deform under sustained load before fracture. During experimentation, it was observed that the average values of ductility indices of using carbon as strengthening material were 1.1 × , 1.2 × and 0.5 × for “ρ” _“s” ^“1” “ = 0.5%,” “ρ” _“s” ^“2” “ = 0.72% and “ “ρ” _“s” ^“3” “ = 1.27%” beam specimens respectively to that of their control specimen. Similarly the average values of ductility indices of using PBO as strengthening material were 2.42 × , 0.75 × and 0.56 × for “ρ” _“s” ^“1” “ = 0.5%,” “ρ” _“s” ^“2” “ = 0.72% and “ “ρ” _“s” ^“3” “ = 1.27%” specimens respectively to that of the control specimen. Also the term energy absorption (Ψ) is defined as the area under the load- deflection curve up to the ultimate load, representing the amount of energy absorbed by the specimen before complete failure. The average values of energy absorption for using carbon as strengthening material were 1.8 × , 1.2 × and 1.6 × for “ρ” _“s” ^“1” “ = 0.5%,” “ρ” _“s” ^“2” “ = 0.72% and “ “ρ” _“s” ^“3” “ = 1.27%” beam specimens respectively to that of the control specimen. Similarly the average values of energy absorption for using PBO as strengthening material were 2.0 × , 1.0 × and 1.5 × for “ρ” _“s” ^“1” “ = 0.5%,” “ρ” _“s” ^“2” “ = 0.72% and” “ρ” _“s” ^“3” “ = 1.27%” specimens respectively to that of the control specimen.
Therefore, both the adopted TRM systems performed exceptionally well within the scope of the work, with carbon TRM system showing a relatively higher increase in the capacity of strengthened specimens and PBO TRM systems exhibiting relatively more ductile failure with higher bond strength between the TRM surface and concrete substrate. Moreover, crack patterns for the strengthened beam showed effective distribution of cracks/damage over the length of beam as compared to severe and concentrated damage in the associated control un-strengthened beams. Further, during the experimentation, it was seen that the technique of applying the TRM system also considers the contractor's ease where the construction workers (although not very skilled) can easily implement the technique after being given simple demonstrations.
The study puts forth proper procedures and standards to the construction industry on the rehabilitation and strengthening of the existing concrete structures using innovative TRM strengthening technique. Successful implementation of the project will result in “state-of-the-art recommendations for design and construction specifications”, which will place Qatar and research at Qatar University in a leadership position not only limited to the Gulf region. Furthermore, this can potentially act as an “important initiation for the development of new industrial opportunities” in the country.
Keywords
Reinforced concrete beams, textile reinforced mortar, flexural strengthening, ductility index, energy absorption.
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The Effect of Chilled Water Supply Temperature on the Energy Efficiency of the Chiller System
Authors: Abdulwahab Alyousef and Abdulwahab BukshaishaA steady-state model for a centralized cooling system is developed and utilized to evaluate its energy efficiency. The numerical model resolves the energy equations for a cooling tower and a centralized water-cooled chiller simultaneously. It requires inputs that are readily available. The user-inputs are the ambient conditions, the cooling tower air flow rate, the condenser water flow rate, the evaporator water flow rate, the superheat and sub-cooling associated with the refrigeration cycle, and the full load design conditions. The model utilizes an empirical relationship for the compressor power as a function of load and temperature, and gives the user an option to select between a constant speed chiller and a variable speed chiller. The outputs include the chiller coefficient of performance, compressor input power and compressor isentropic efficiency. This talk will discuss the results of the assessment conducted of the effect of chilled water supply temperature on the performance and energy efficiency of the chiller system. The findings and recommendations on how to optimize chiller systems for best energy performance will also be presented.
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Comparative Analysis of Antifungal Activity of Total Phenolics from Different Date Palm Cultivars Against Five Phyto Pathogenic Fungi
Authors: Resna Nishad and Talaat AhmedIntroduction: Pathogen attacks impose natural selection on plants to evolve complex arrays of defensive strategies. Among the diverse defensive mechanisms evolved by plants to withstand pathogen attack, the ability to synthesize an arsenal of low-molecular weight volatile and non-volatile chemicals including phenolics helps them to prepare a robust defense response against pathogen entry. Systemic induction and accumulation of low molecular weight phenolics is observed in response to various diseases and thus are studied as markers for resistance to pathogens. Phenolics that exhibit anti-oxidant activity exert their inhibitory effects on pathogen colonization via protein precipitation and iron depletion.
Phytochemical analysis have been proved that date palm is rich source of phenol. Very little information is available on the inherent Date palm phenolic content that has been involved as resistance factors. All the studies are focused on phenolic content from date palm fruit and its property. Here we focusing on comparative analysis of phenolics from different cultivars leaf and how it affect the different pathogenic fungi. Material and Methods: We conducted a genome mining analysis of date palm whole genome available in the NCBI site, to detect the presents of enzyme involved in the secondary metabolite pathway. Analyzed the presents of receptor protein specific for the recognition of fungal pathogen.
Five date palm pathogens were isolated from the diseased date palm and surrounding soil from the date palm field located in northern region of Qatar. Leaf, shoot and root samples collected from the diseased date palm and rhizosphere soil collected from near the diseased date palm. Samples were stored at 40?C in aseptic condition until further use. Sterilized plant samples were plated in the potato dextrose agar (PDA) for the fungal isolation and the soil were plated on molten agar for fungal isolation. The plates were incubated at 250?C until single colony appeared. The isolated fungi were examined under microscope. Based on the microscopic and physical characteristics fungi were identified.
The pathogenicity were determined with detached leaf inoculation analysis and in vivo pathogenicity analysis with three date palm cultivar varieties. Detached leaf inoculation analysis performed in laboratory condition and the in vivo pathogenicity conducted in green house with controlled growth condition. The date palm varieties used in this current study are Khalas, Khneezi and Barhi. All the four pathogens, Fusarium solani, Fusarium oxysporum, Rhizectonia solani Fusarium sp and Ceratocystis radicicola were used for pathogenicity analysis.
Total phenolic were extracted from three date palm culvars through water extraction procedure. Extraction performed with different temperature range. Comparative analysis of antifungal property of total phenolics from different date palm cultivars such as Khalas, Khneezi and Barhi was carried out after optimizing extraction temperature. Antifungal activity is determined with disc diffusion analysis. 100 μl of extract impregnated filter disc (10 mm in diameter) placed on the PDA plate followed by fungal disc placed on the disc. Plates were incubated at 250?C and the fungal growth monitored. Experiment repeated in triplicate along with control. Results and conclusion: The genome mining analysis of date palm result revealed 45 enzyme sequences from shikimate pathway, which is a support for the active synthesis of phenolic content in date palm. Plant phenolics synthesize via shikimate-phenylpropanoid-flavonoid pathways and include phenolic acids, flavanoids, tannins and less common stilbenes and lignins. Presents of chitin elicitor receptor kinase in date palm indicate the phytopathogenic fungal detection ability of date palm.
From the isolated fungi, the date palm pathogenic fungi were screened and subcultured. Five pathogenic fungi were isolated, Fusarium solani, Fusarium oxysporum, Rhizectonia solani, Fusarium sp and Ceratocystis radicicola. Pathogenicity of all the five isolated fungi were confirmed by analyzing necrosis caused on the date palm leaf (Fig. 1). The frequency of necrotic lesion and disease susceptibility found more in Khneezi than Khalas and Barhi.
Water extraction procedure conducted at 400?C for 24 hrs were accepted as standardized phenolic extract for antifungal activity. Growths of the fungi were measured after 3 day and 5 days of incubation to determine the antifungal activity of phenolic extract (table 1). Phenolic extract from the Khalas showed more antagonistic activity against Rhizectonia solani whereas phenolic extract from Barhi showed more inhibitory activity against Fusarium solani, Fusarium oxysporum and Ceratocystis radicicola. In all the experiment Khneezi showed week inhibitory activity this supports our previous susceptibility study (not published) in that Khneezi showed more susceptible to C.radicicola. This result is an evident for the disease resistant activity of date palm phenolics.
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Sampling of Qatari Sand Microbes: Serious about B.cereus
Authors: Umm-Kulthum Umlai, Annette Shoba Vincent and Vincent IlyinObjective: A shortage of studies regarding the ecology of Qatar led to the sampling sand to determine the composition of microbes within the sand (below a certain size). This sampling began with a sand sample obtained from Al Rayyan, Doha Qatar. The sample was purified, and sequenced after isolating the DNA. A comprehensive analysis of the local Qatar sand sample shows a range of various microbes (which are smaller than 0.2 micrometer), which exist in the sand. Among these organisms was Bacillus cereus a bacterium from the Bacillus family that is most commonly responsible for mild food poisoning. The genes are being studied further to understand better what the sand microbial composition is like. Furthermore, it will help us better understand the genomes of these microbes and possibly how the proteins allow them to survive within the sand. Method: After obtaining the sequenced DNA, a Short Oligonucleotide Analysis Package- Denovo (SOAP-Denovo) system that helps assemble the genetic information into short reads called contigs was used. In addition to this, another program called Velvet was also used in conjunction to ensure the best results were obtained using the optimal k-mer, providing the longest contig length. The longest length obtained was a contig of 12,380 at a k-mer of 59. Subsequently, the results of the assembly program were assembled into nucleotide and protein sequences using the gene prediction software, GeneMarkS available online. Each of the genes from the contigs were then searched against the National Centre for Biotechnology Information (NCBI's) online database using Basic Local Alignment Search Tool (BLASTp) which utilizes certain algorithms to compare the protein input sequences in FASTA format to the entire non redundant protein database of available sequenced genes. This tool provided us with a possible list of the gene's (percentage) identity, along with the maximum and total scores, the query cover (percentage of sequence that matches that available for a particular organism's gene) and the E-value (the smaller the value the less the probability of the similarity occurring due to random chance) in order to assess the probability that the results are accurate. All this data was collected are currently being analyzed further. Results: It was found that the microbe majorly contributing to presence in the sand was Bacillus thuringensis with 50%, closely followed by Bacillus cereus with 40%, 5% Methylobacterium, 3% Enterobacteriophages, 2% other forms of Bacillus species and finally some traces of Streptococcus pneumonia as well as some other organisms. Bacillus thuringiensis or Bt is a common biological pesticide used in agriculture and is safe for human consumption; this bacterium is a common soil dwelling organism. Bacillus cereus on the other hand is less safe for human consumption as it produces harmful toxins that cause mild food poisoning and it is similarly a soil-dwelling microbe. Methylobacterium, are bacteria that are usually found in soil and are the natural flora found on the ground. Enterobacteriophages are bacteriophages that commonly infect E.coli. And finally Streptococcus pneumoniae are pathogenic bacteria that exist in the body but are the main causative agents of pneumonia in humans when they exceed a certain threshold or if the immune system is vulnerable. Discussion: The results showed that the microbes did not share 100% identity with their respective matches. There is a high chance that the small percentage differences (which ranged from 1-6%) could be due to mutations that enable the microbes to adapt to their environment's temperature. For example, some of the B.cereus genes that have undergone mutation are those that code for polysaccharide synthase (94% identity), histidinol dehydrogenase (99%), a capsular polysaccharide biosynthesis protein (99%), or a sodium/hydrogen exchanger (also 99%). Future work: In order to verify the presence of the organism in the sand, there will need to be more samples, and a repeat of the experiments. With repeated experiments, the organisms will not be filtered; the threshold for the size of microbes will be increased, allowing for a greater view of the composition of the sand samples in Qatar. This will allow us to gain a better picture of microbial life in the ecology of Qatar; especially in terms of the presence of pathogenic microbes.
The sand samples will be cultured and grown on blood agar plates and the microbes would be identified through morphological characteristics. A repeat of the DNA isolation and sequencing will be carried out to confirm the presence of the microbes such as B.cereus. Furthermore, PCR tests will have to be conducted using universal primers for 16sRNA of certain bacteria as a control, to check against the DNA extracted from the sand sample during the initial round of DNA sequencing. If any of the genes are the same as the B.cereus from the first time, it would be confirming its presence in the sand.
It would be possible also to design primers specific for B. cereus in order to develop a convenient method of testing for such organisms. This could be extremely useful for test in food since food poisoning is commonly caused by these easily detectable and curable microbe infections. This could help reduce the level of food poisoning in the country, which is quite a common occurrence in Qatar.
In future studies, more samples could be taken from various parts in Qatar, as well as at a range of different depths within the sand, to further increase our knowledge of the types of microbes present in the ecology.
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Experimental Investigation on Gasoline and Diesel Fuels Surrogates Designed Via Computation and Property Integration Methods
Authors: Nimir Elbashir, Saad Intikhab, Sawitree Kalakul, Hanif Ahmed Choudhury and Rafiqul GaniAutomotive researchers attempts to simulate combustion of fuels in order to improve engine performance.[1] Conventional fuels are difficult to represent in these simulations due to their complex composition. Surrogates that meet American Society of Testing and Materials (ASTM) standards are a good alternative to conventional fuels. This study aims at design and analyzing surrogate mixtures for both gasoline and diesel. Surrogates were designed through a computer aided model developed at the Technical University of Denmark.[2] The model architecture has four structures viz., (i) problem definition (ii) property model identification (iii) mixture blend design and (iv) model-based verification.
Surrogate diesel, comprised of five paraffinic compounds viz., n-dodecane, n-tetradecane, tetralin, cyclo-octaneand iso-cetane in different volumetric ratios. Surrogate gasoline comprised of six different chemicals viz. n-butane, n-heptane, iso-octane, 1-pentene, methyl cyclopentane and toluene in different volumetric ratios. Target physical properties of these fuel surrogates were measured using advanced analytical equipment and experimental techniques developed at Texas A&M University at Qatar.[3] Diesel surrogate was tested for the target properties employed in the model viz. density, viscosity, heat content, flash point, vapor pressure, pour point, cloud point and distillation curve. Butane present in the gasoline surrogate hampers handling and testing since it is extremely critical to prepare a homogeneous blend that comprises of both liquids and a permanent gas. Also, the conventional sampling technique was found to be ineffective to prevent loss of permanent gas in the surrogate. Therefore, a novel sampling methodology and advanced blending technique was developed to minimize loss of butane and volatile components such as 1-pentene. Detailed Hydrocarbon Analysis (DHA) for gasoline surrogate was carried out by Gas Chromatography (GC) according to ASTM D6730 to verify the efficacy of blending technique as well as sampling method. The composition analysis through DHA confirmed that the blending and sampling methodology was accurate with maximum relative standard deviation of approx. 5.82%. Subsequently gasoline surrogate was tested for density, viscosity, vapor pressure, heat content, distillation curve and compositional attributes.
The surrogate mixtures prepared in this study complied well with their respective ASTM standards for the properties measured. The work would further be continued to investigate the engine performance and emission characteristics for diesel surrogate. Engine performance will be evaluated in terms of Power/Torque and Theoretical Brake Specific Fuel Consumption (BSFC). Emissions of Carbon Monoxide (CO), Hydrocarbon (HC) and Nitrogen Oxides (NOx) will be determined. Results of this study provide a basis to further improving the computer aided models used to design the surrogates and for design of future generations of efficient fuels of different composition obtained from both conventional sources (petroleum) and non-conventional sources (e.g. from natural gas via gas-to-liquid (GTL), coal via coal-to-liquid (CTL) or biofuels). Also, the outcome of this study will be used to optimizing the design of fuel blends obtained from the aforementioned sources.
References
[1] Pitz, W. J., & Mueller, C. J. (2011). Recent progress in the development of diesel surrogate fuels. Progress in Energy and Combustion Science, 37(3), 330–350.
[2] Yunus, N. A., Gernaey, K. V., Woodley, J. M., & Gani, R. (2014). A systematic methodology for design of tailor-made blended products. Computer and Chemical Engineering, 66, 201–213.
[3] Elmalik, E.E., Raza, B., Warrag, S., Ramadhan, H., Alborzi, E., Elbashir, N.O. (2014). Role of Hydrocarbon Building Blocks on Gas-to-Liquid Derived Synthetic Jet Fuel Characteristics. Industrial & Engineering Chemistry Research, 53, 1856–1865.
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Study and Comparison of PFC Rectifiers: Quasi Z Source, Traditional Flyback
Authors: Sinan Asaad Sabeeh and Fahad AlhuwaishelThis study focuses on comparing the Traditional Flyback PFC (F-PFC), and the Quasi Z-Source PFC (QZS PFC) on range of (36–720W) and input Voltage of (130, 200, 230V) with an output Vdc of 36 Volts while operating in Continuous Conduction Mode. The study has confirmed that F-QZS PFC has better THD%, P.F, and lower output current and voltage ripple relative with the output power. In addition, the stress on each main element has been explored and it was confirmed that the F-QZS has robust measured voltage and current across the elements due to the effect of crossed capacitance topology in the F-QZS while the F-PFC suffers from high spikes. Finally, a very precise closed loop duty ratio control was developed to optimize the performance of the F-QZS PFC.
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Growth of Hybrid Perovskites (HP) Light Harvesting Layer and TiO 2 Electron Transport Material for Solar Cells Application
Hybrid Perovskites (HP) recently emerged as alternative light harvesting layer to fabricate high efficiency thin film solar cells. The perovskite based solar cells took advantage of the experience gained in the field of the dye sensitizes solar cells and the extremely thin absorber (ETA) solar cells. It is worth mentioning that the structure of the perovskite solar cell is very similar to a dye sensitized solar cell and ETA solar cell. These cells are composed of the transparent conducting layer (TCO), the electron transport material (ETM) the absorber, the hole transport material, and the back contact. Our work focuses on the deposition and characterization of two components of the perovskite based solar cell. These components are the ETM which is titanium dioxide layer (TiO2) in this case and the absorber material which is the perovskite layer. Dip coating technique was used to grow compact and pinhole free TiO2 films from a solution of Titanium alkoxide diluted in isopropanol. The dip coating technique is particularly attractive for thin film solar cell application due to its simplicity, low cost, and good quality of films. For a compact film, dipping was restricted to two dips and four dips. The films were structurally and morphologically characterized by X-ray diffraction and scanning electron microscope (SEM). XRD analysis showed the deposited TiO2 films have anatase structure. SEM results showed a full coverage of the films with less pinholes. The two step sequential physical vapour deposition was performed to grow HP thin films using thermal evaporation technique. Thin films of HP were deposited using thermal evaporator under high vacuum from two sources namely lead iodide and methylamine iodide. Firstly, Lead iodide was deposited which acts as a template for the crystallization of perovskite layers. Then methylamine iodide was deposited for the desired film. X-ray diffraction of the as deposited film showed the presence of mixed phases of lead iodide and perovskites. This indicates at room temperature methylamine iodide diffused deep enough in the lead iodide film to form the perovskite structure. Films were then annealed at 110 °C for 1 hour in nitrogen atmosphere for better crystallinity which is proven by the sharper and high pick intensities. Also, varying the ratio of both organic and inorganic sources did not influence the presence of lead iodide phases as confirmed by XRD. Further optimization are in progress to form single perovskite phase formation.
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