Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1
- تاريخ المؤتمر: 22-23 Mar 2016
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2016
- المنشور: ٢١ مارس ٢٠١٦
101 - 150 of 656 نتائج
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Machine Learning-Based Building Energy Consumption Prediction
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: Hassan Ali FarragThe 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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)
المؤلفون: 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
المؤلفون: Adel Obaid SharifDesalination 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
المؤلفون: 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?
المؤلفون: 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)
المؤلفون: 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
المؤلفون: 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
المؤلفون: Maria Fernanda Torres, Lisa S. Mathew, Candice Purchase, Yasmin A. Mohamoud and Joel A. MalekDate 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
المؤلفون: Zacharie Tamainot-TeltoMost 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
المؤلفون: 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)
المؤلفون: 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.
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7. L. Mohapatra, K. M. Parida, Phys. Chem. Chem. Phys., 2014, 16, 16985–16996.
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Ionic Liquids as Multi-purpose Inhibitors to avoid Natural Gas Hydrates during Gas Processing
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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?
المؤلفون: 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
المؤلفون: Ann-Marie Grace HarikSandstorms 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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
المؤلفون: 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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