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Qatar Foundation Annual Research Conference Proceedings Volume 2018 Issue 1
- Conference date: 19-20 Mar 2018
- Location: Qatar National Convention Center (QNCC), Doha, Qatar
- Volume number: 2018
- Published: 12 March 2018
1 - 100 of 142 results
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Novel low band gap polymers based on pyrrolo[32d:45d’]bisthiazole PBTz and thienylenevinylene TV For Organic Electronic Applications
Authors: Dhananjaya Patra, Hassan S Bazzi, Lei Fang and Mohammed Al-HashimiNovel low band gap polymers based on pyrrolo[3,2-d:4,5-d′]bisthiazole (PBTz) and thienylenevinylene (TV) For Organic Electronic Applications Dhananjaya Patra?,1 Hassan S. Bazzi,1 Lei Fang¬2 and Mohammed Al-Hashimi1 1Department of Chemistry, Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar 2Department of Chemistry and Department of Materials Science and Engineering, Texas A&M University, College Station, TX. Corresponding author: [email protected] π-Conjugated organic polymers have been intensively studied over the past two decades due to their potential applications in areas such as organic light-emitting diodes (OLEDs),1 organic thin-film transistors (OTFTs), organic photovoltaics (OPV), and organic laser devices. In addition, they possess excellent properties that enable them to be solution processed offering a path-way for fabrication on large-area printable and cost-effective flexible electronic devices. Several donor-acceptor (D-A) conjugated polymers and small molecules are reported recently with photovoltaic performance over 12%.2-4 Recently significant development has been made in the design and synthesis of high performance polymers with mobilities now easily surpassing μ > 1 cm2 V-1 s-1.5 Among the various conjugated electron-donating building blocks, thienylenevinylene (TV) unit has attracted much interest owing to its coplanarity and extended π-conjugation which are induced by the presence of a vinylene spacer between the two thiophene units. As a result this enhanced interchain interaction the polymers exhibit a higher hole mobility and reduced energy band gaps.4 Recently, the incorporation of vinylene unit into several electron-rich (i.e., donor) and electron deficient (i.e., acceptor) units has been widely studied, especially, targeting at the device application for n-channel and ambipolar OTFTs with promising device performance. Among these units are diketopyrrolopyrrole (DPP), benzoselenadiazole (BSe), phthalimide (PhI), naphthalenediimide (NDI), benzothiadiazole (BT), dithienothiophene (DTT), thienopyrroledione (TPD), and isoindigo (iI) as depicted in Figure 1. For instance, Yoo et al. reported the synthesis of various polymers based on DPP and (E)-2-(2-(thiophen-2-yl)-vinyl)thiophene units by altering the number of thiophene in the repeat unit to induce strong π–π stacking and favorable molecular conformation. By replacing the thiophene unit with the selenophene vinylene selenophene Kang et al. reported an enhanced mobility. Several DPP and TV based polymers reported by Oh and Kim et al. via various side-chain engineering on the DDP units, obtained remarkable mobilities from 8.74 to 17.8 cm2 V − 1 s − 1.5 Reichmanis and co-workers also reported the synthesis of a series of BT oligothiophene and oligo-TV donor-acceptor (D − A) copolymers exhibiting mobilities of up to 0.75 cm2 V − 1 s − 1. Kim and co-workers reported the synthesis and characterization of highly soluble poly(thienylenevinylene) exhibiting carrier mobility of 1 cm2 V − 1 s − 1.6 Al-Hashimi, Heeney and co-workers systematically investigated the role of modifying the heteroatom, by synthesizing a series of vinylene copolymers containing 3-dodecylthiophene, selenophene and tellurophene.7,8 Figure 1. Structures of thiophene (Th), thiazole (Tz) diketopyrrolopyrrole (DPP), benzoselenadiazole (BSe), phthalimide (PhI), naphthalenediimide (NDI), benzothiadiazole (BT), dithienothiophene (DTT), thienopyrroledione (TPD), and isoindigo (iI). Another particularly promising class of building block for the development of high performing polymeric semiconductors for OTFTs is the electron-deficient pyrrolo[3,2-d:4,5-d′]bisthiazole (PBTz)-based heterocycle. In comparison to dithienothiophene (Figure 1), PBTz-unit is a weak acceptor having an electronegative nitrogen atom, which lowers the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies. Therefore, it is expected that the large polarity of the thiazole ring can enhance the intermolecular interaction. In addition, the bridging nitrogen (N) of PBTz offers the opportunity to include an additional solubilizing sidechain, which is not present in the analogous DTT. This potentially offer improved solubility and processability of the polymers. Nonetheless, to the best of our knowledge, there is no single report on the synthesis, polymer characterization, and charge carrier transport properties employing the fused PBTz containing TV units. In this work, we report the synthesis and characterization of a series of four PBTz-TV-based copolymers P1-P4 (Scheme 2) with various alkyl side chains for OTFT applications. Particularly, we have selected a dodecyl alkyl side chain on the thienylenevinylene unit, three branched alkyl side chains such as 2-octyldodecyl (OD), 9-heptadecyl (HD) and 2-ethylhexyl (EH), and a long straight n-hexadecyl (HD) chain on the nitrogen of the pyrrolobisthiazole unit, thus, for improving polymer solubility and effectively to promote π − π interchain interactions. The electrochemical redox properties and related electronic structures (HOMO/LUMO energy levels) were systematically investigated by cyclic voltammetry (CV). In addition, the microstructure and morphology of the polymer thin films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). Finally, the PBTZ-copolymers show band gaps in the range of 1.40 − 1.46 eV and mobilities in the range of 0.002-0.062 cm2 V − 1 s − 1 in bottom-gate/top-contact OTFTs.9 References. 1. Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R. N.; Mackay, K.; Friend, R. H.; Burn, P. L.; Holmes, A. B. Nature, 1990, 347, 539. 2. Sekitani, T.; Zschieschang, U.; Klauk, H.; Someya, T. Nat. Mater.,2010, 9, 1015.3. Zhao, W.; Li, S.; Yao, H.; Zhang, S.; Zhang, Y.; Yang, B.; Hou, J. J. Am. Chem. Soc., 2017, 139, 7148. 4. Li, N.; Baran, D.; Forberich, K.; Machui, F.; Ameri, T.; Turbiez, M.; Carrasco-O., M.; Drees, M.; Facchetti, A.; Krebse, F.C.; Brabec, C. J. Energy Environ. Sci., 2013, 6, 3407. 5. Kim, J.; Lim, B.; Baeg, K. J.; Noh, Y. Y.; Khim, D.; Jeong, H. G.; Yun, J. M.; Kim, D. Y. Chem. Mater.,2011, 23, 4663. 6. Fu, B. Y.; Baltazar, J.; Hu, Z. K.; Chien, A. T.; Kumar, S.; Henderson, C. L.; Collard, D. M.; Reichmanis, E. Chem. Mater.,2012, 24, 4123 7.Al-Hashimi, M.; Han, Y.; Smith, J.; Bazzi, H. S.; Alqaradawi, S. Y. A.; Watkins, S. E.; Anthopoulos, T. D.; Heeney, M. Chem. Sci.,2016, 7, 1093. 8. Al-Hashimi, M.; Baklar, M. A.; Colleaux, F.; Watkins, S. E.; Anthopoulos, T. D.; Stingelin, N.; Heeney, M. Macromolecules, 2011, 44, 5194. 9. Patra, D.; Lee, J.; Lee, J.; Sredojevic, D. N.; White, A.J.P.; Bazzi, H. S.; Brothers, E. N.; Heeney, M.; Fang, L.; Yoon. M.-H.; Al-Hashimi, M. J. Mater. Chem. C., 2017, 5, 2247.
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Concentrated photovoltaic system with a phase change material: A system to harness solar energy more efficiently as compared to a conventional photovoltaic system for Qatar climatic conditions
Authors: Jawad Sarwar, Ahmed E Abbas and Konstantinos E KakosimosConcentrated photovoltaics (CPV) is advantageous as compared to a conventional non-concentrated photovoltaic (PV) system due to its ability to increase PV cell efficiency and replacing expensive PV material with an abundant and inexpensive reflective or refractive concentrator material. In this work, an overall solar to electrical and thermal conversion efficiencies between a concentrated photovoltaic system thermally regulated by a phase change material (CPVPCM) and a PV system is compared for Qatar climatic conditions. The electrical and thermal behavior of both, CPVPCM and PV, systems are simulated using an already developed and validated coupled electrical-thermal and optical model. A crystalline silicon PV cell is selected which has an electrical conversion efficiency of 14% and temperature dependent maximum power loss coefficient of -0.45% K-1 at standard test conditions. The width of the PV cell is 0.015 m for the CPVPCM system while a 6” × 6” PV cell is considered for the conventional PV system. The same footprint of 1 m2 is selected as a physical equivalency criterion for both systems to compare their electrical and thermal output. Therefore, 36 PV cells, connected in series, represents footprint of 1 m2 for conventional PV system while the length and configuration of the PV cell for a CPVPCM system depend on the concentration ratio and type of concentrator to achieve equal footprint of 1 m2. The CPVPCM system uses a parabolic trough concentrator to focus sunlight onto a PV cell. The concentration ratios of 10 × , 15 × and 20 × are considered in this work, which results in lengths of 5.34 m, 3.56 m and 2.67 m to achieve 1 m2 footprint. An increase in incident irradiance density due to concentration instantaneously generates more power from a PV cell in any CPV system. However, it also increases the PV cell temperature and reduces power output because of the temperature dependent negative power coefficient of PV cells. The electrical power output loss due to temperature diminishes the gain in the electrical output due to the concentration of the irradiance. Furthermore, the elevated PV temperature also results in associated degradation mechanisms such as thermal aging, delamination, and mechanical damages. Therefore, cooling of a PV cell in a CPV system is essential to prevent the net power loss and gain the advantages of increased incident irradiance density. Four different commercially available solid-liquid phase change materials (PCM) are investigated for passive cooling of the CPVPCM system. The PCMs absorb and store excess heat during solid to liquid phase change and thereby, regulate the temperature of the PV cell. The heat storage by PCMs also leads to a potential utilization of thermal energy trapped within the PCM. The selection of a PCM depends on its several thermophysical properties such as melting temperature, latent heat of fusion, density, congruency, and stability. In this work, the selected PCMs are Lauric acid, RT42, S-series salt, and ClimSelTM C48 which are reported to have congruency and cyclic thermal stability as per manufacturers' data sheet. The PCMs have melting temperatures ranging from 41 oC to 54 oC and latent heat of fusion in the range of 178 kJkg-1 – 220 kJkg-1. The PCMs are encapsulated inside an aluminum container behind the PV cell. The aluminum container is made of 3 mm thick aluminum sheet having outer dimensions of 0.105 m × 0.042 m and inner dimensions, to contain PCM, of 0.099 m × 0.036 m. The lengths of the aluminum container are 2.67 m, 3.56 m and 5.34 m for concentration ratio of 20 × , 15 × and 10 × respectively. Two consecutive days of each month of a year are selected to simulate the optical, thermal and electrical behavior of both systems. The direct beam irradiance is obtained using the clear sky Bird's model while weather conditions such as ambient temperature and wind conditions are obtained from experimentally measured data from Qatar meteorological department. Since single axis tracking is a pre-requisite for parabolic trough concentrator; therefore, single axis tracking for PV system is considered as well to achieve equivalency regarding input conditions as well. The temperatures of the PV cells, IV curves to calculate maximum power point, the instantaneous power produced over a day using maximum power point tracking, total power produced over a day, and thermal energy storage in the PCMs are predicted by performing simulations of the electrical, thermal and optical behavior of both systems. It is found that the salt performs better than all other selected PCMs due to its high-energy storage density. The electrical output of the CPVPCM for concentration ratio of 10 × and 15 × is greater than the PV system and comparable at a concentration ratio of 20 × . However, the CPVPCM also store thermal energy, therefore, achieves higher overall solar to the electrical and thermal conversion efficiency as compared to the conventional PV system. Further studies are required, using experimentally measured irradiances instead of using a clear sky model, to investigate and compare the overall conversion efficiencies of the CPVPCM and conventional PV systems.
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Longterm Seasonal Variability of Photovoltaic Surface Soiling and Subsequent Power Loss in Doha Qatar
Authors: Wasim Javed, Bing Guo, Benjamin Figgis and Yiming WubulikasimuDust accumulation or soiling on solar panels' and collectors' surfaces has become a well-known problem, which severely reduces the performance of solar energy conversion systems. The soiling of the solar surfaces is a complex phenomenon influenced by various site-specific environmental and weather factors, and therefore should demonstrate seasonal and weather-dependent trends. Such information of natural PV soiling would be useful not only for modeling the economic impact of surface soiling but also for properly scheduling of cleaning, which is of interest to project developers and operators. The purpose of the study is to investigate the long-term seasonal patterns of airborne dust accumulation on PV modules and soiling-induced PV performance degradation in the desert environment of Qatar. PV performance, ambient dust concentration and meteorological data were collected over the study period of 2014-2017. Results revealed that PV performance due to soiling in terms of daily change in the cleanness index (ΔCI) varied with season, which was attributed to substantial variations in environmental conditions (i.e., rainfall, wind speed, humidity, temperature, airborne dust concentration). Averaged over the four years, the daily ΔCI was − 0.43 ± 1.0% per day for modules cleaned every sixth month, and − 0.46 ± 1.05% per day for modules cleaned every second month or about 14% per month. The annual pattern shows significant seasonal variation of daily ΔCI and cumulative CI during the study period. Daily ΔCI was found to be the most severe during November ( − 0.75%) and least during June ( − 0.19%). The months correspond to the rainy season (i.e., February to April) have moderate values of ΔCI ( − 0.34%). It was observed that average daily ΔCI by month was decreased with increasing PM10 concentration and humidity and increased with that of temperature and wind speed. The intense dust storm and rainy events taking place on specific days of the month are predominantly responsible for the large month-to-month variations of PV soiling. A yearly soiling trend was also determined that could help to reduce uncertainty in energy yield prediction. Monthly dust deposition on PV modules was also determined gravimetrically, which also showed month-to-month variation following the same trend of monthly PV performance loss. In addition to the environmental factors affecting dust accumulation on PV modules, particle size distribution and chemical properties of the monthly-collected dust were investigated and compared as well.
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Slurry Electrode Properties of Carbon Nanotubes and Graphene for Flow Cell Energy Storage Applications
By Ahmed SodiqRedox Flow Batteries (RFBs), among other options, is uniquely suited for large-scale Electrical Energy Storage (EES) due to many advantages over the conventional sealed batteries (e.g., lead-acid and Li-ion batteries). Owing to its design flexibility, flow batteries can meet a wide range of commercial-scale EES applications with varying power-to-energy ratios. In addition, flow batteries have excellent energy efficiency and competitive life-cycle cost and are considered to be inherently safer compared to conventional sealed batteries. Despite its attractiveness and demonstrated performances, flow battery technology still suffers from high system capital cost (which limits its potential deployment into grid storage applications) and low energy density of the reactant fluids (which leads to large footprint and makes it impractical for EES applications with confined spaces). These challenges can be addressed if higher energy density and cheaper battery materials are developed. An attractive approach has been recently proposed, where the active materials are mixed with carbon to create a flowable electrode (otherwise known as slurry electrode). This system helps to operate flow battery with increased concentration of redox species and as a result the energy density is significantly improved.Slurry electrode (shown in Fig. 1) has been defined as “a suspension of particles with large double-layer capacity, such as activated carbon, in an electrolyte solution” [1]. These particles transfer charge from an electrochemical cell to an external reactor, where a substance is oxidized or reduced, and are recharged in the cell [1]. Unlike conventional RFB system, the semi-solid technique uses fluid electrodes that are electronically conductive [2]. Slurry electrodes are characteristically dynamic, particles continuously move and continuously make and break contact with one another. Percolation theory defines a critical loading, fc, above which there are enough particles in the slurry that, at any point in time, a constant network of particles is formed that spans the distance from one boundary to another [3]. It is due to these networks of percolated particles that slurries (with sudden increase in conductivity and viscosity at percolation) are able to conduct electrons out into the electrode and away from the current collector to utilize the high surface area of the particles for electrochemical processes [4, 5]. Other advantages of slurries involve their ability to have high surface areas, simple assembly and ease of maintenance through filtering (for example the carbon materials can be recycled without necessarily opening up the cell). The performance of slurry-electrode-based flow batteries highly depends on the features of the interaction between the particles and current collectors. Parameters such as storage duration or maximum power can be tuned by adjusting the properties of the slurry, being extremely important are the ionic and electrical conductivities of the slurries. Figure 1 In this presentation, the performance of slurry electrodes, based on carbon and redox systems (Vanadium/CNTs and Vanadium/Graphene), focusing in particular on electrochemical performance, conductivity, corrosion, and cell performance will be presented. We achieved high electrochemical activities in the case of Vanadium/CNTs as compared with Vanadium/Graphene as shown in Fig. 2. According to the structural features of the CNTs; the oxygen functional groups improve the hydrophilicity of the electrode. The O = C-OH groups on the CNTs probably behave as active sites, and facilitate the reactions of VO2+/VO2+ redox couple. Figure 2 References [1] B. Kastening, et al., «Design of a slurry electrode reactor system,» Journal of applied electrochemistry, vol. 27, pp. 147-152, 1997. [2] Z. Li, et al., «Aqueous semi-solid flow cell: demonstration and analysis,» Physical Chemistry Chemical Physics, vol. 15, pp. 15833-15839, 2013. [3] L. Gao, et al., «Effective thermal and electrical conductivity of carbon nanotube composites,» Chemical Physics Letters, vol. 434, pp. 297-300, 2007. [4] T. J. Petek, et al., «Characterizing Slurry Electrodes Using Electrochemical Impedance Spectroscopy,» Journal of The Electrochemical Society, vol. 163, pp. A5001-A5009, 2016. [5] H. Parant, et al., «Flowing suspensions of carbon black with high electronic conductivity for flow applications: Comparison between carbons black and exhibition of specific aggregation of carbon particles,» Carbon, vol. 119, pp. 10-20, 2017/08/01/ 2017. [6] H. Yoon, et al., «Pseudocapacitive slurry electrodes using redox-active quinone for high-performance flow capacitors: an atomic-level understanding of pore texture and capacitance enhancement,» Journal of Materials Chemistry A, vol. 3, pp. 23323-23332, 2015.
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Biomass distribution and soil characteristics along the distance from the coast in a natural mangrove forest in Qatar
Authors: Yowhan Son, Hanna Chang, Seung Hyun Han, Jusub Kim and Juha AlataloMangrove is a woody plant which grows in intertidal zones. Mangrove forests are mainly distributed in subtropical and tropical regions, and are valuable for ecosystems and for society. Even in dry regions such as Qatar, mangrove forests provide ecosystem services despite their small area and low productivity compared with tropical mangroves. Carbon sequestration by mangroves is one of the main ecosystem services mitigating climate change, as mangrove forests are carbon-rich ecosystems. In mangrove forests, there is a natural gradient in soil environments between land and sea. Soil salinity and water availability are the major factors influencing mangrove productivity. The objectives of this study were (1) to investigate the change in biomass of Avicennia marina, the only mangrove species in Qatar, along the distance from coast and the relationship between biomass and soil characteristics, and (2) to estimate carbon storage of biomass in a natural mangrove forest in Qatar. Three plots were established in a natural mangrove forest of A. marina in Al-Thakira, Qatar (25°42»15.9»N 51°32»18.4»E), at a distance of 0 m (D0), 50 m (D50), and 100 m (D100) from the coast. Plot size was 2 × 2 m2, 3 × 3 m2 and 4 × 4 m2 at D0, D50, and D100, respectively. Plant abundance was determined by counting the number of individual seedlings ( ≤ 1.3 m high) and trees (>1.3 m high) per plot. Diameter at breast height (DBH) was measured on trees in each plot, and above-ground biomass (AGB) and below-ground biomass (BGB) of trees were estimated using allometric equations for A. marina. Carbon storage in biomass was calculated by carbon fraction of 45.1%. Soil samples at 0-10 cm depth were collected at three random points per plot. Soil samples were air-dried and sieved through a 2 mm mesh screen, and then pH, salinity, water content and nitrogen (N) concentration of each soil sample were measured. Differences in biomass of trees, pH, salinity, water content and N concentration of soil at each distance were analyzed using t-test (SAS 9.4 software). Seedling abundance (no. m-2) was 2.4 ± 0.1 at D0, 7.9 ± 0.8 at D50, and 1.9 ± 0.2 at D100, while tree abundance was 0.9 ± 0.1 at D50 and 1.2 ± 0.1 at D100. There were no trees at D0, so comparisons with this site were excluded. AGB was significantly higher at D100 (41.4 ± 1.9 Mg ha-1) than at D50 (7.3 ± 0.9 Mg ha-1). BGB was higher at D100 (44.9 ± 0.6 Mg ha-1) than at D50 (19.4 ± 2.3 Mg ha-1), but there was no significant difference between two distances. Salinity, water content, and N concentration of soil were 125.1%, 196.3%, and 114.5% higher, respectively, at D100 than at D50 (all differences were significant). Soil pH was significantly 3.1% lower at D100 than at D50. It was reported that growth and biomass of mangroves increased slightly and then decreased continuously along the salinity gradient. However, salinity at the study site was low compared with that in other mangrove forests and might be within the range that biomass increases with salinity. A. marina required a large amount of water and nutrients in high salinity condition (Naidoo, 2009). High water content and N concentration of soil at D100 could meet the requirement for water and nutrient in high salinity condition, and thereby result in the biomass increment. In this study, carbon storage (Mg C ha-1) was 7.3 ± 1.1 for AGB, 9.7 ± 1.1 for BGB, and 18.1 ± 2.4 for total biomass of A. marina. These values are lower than those reported for A. marina in temperate regions (AGB: 57.7 Mg C ha-1, BGB 69.8 Mg C ha-1), subtropical regions (AGB: 49.6-73.1 Mg ha-1, BGB: 49.2-56.8 Mg ha-1), and even dry regions (20.7-66.6 Mg C ha-1). To conclude, biomass of A. marina increased as the distance from the coast and was affected along the gradient of soil characteristics. A better understanding of mangrove biomass distribution between land and sea will contribute to estimate biomass and carbon storage in intertidal zones. * This study was supported by Korea Ministry of Environment (2014001810002).
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Geographical distribution of air pollution in Doha Qatar
Authors: Mariem Safi and Elnaiem Ali ElobaidUrban air pollution is an inevitable consequence of the urbanization representing a growing concern to scientists, policymakers and an increasing fraction of the population. Air pollution is an acute problem especially in the developing countries, where the growing population, developing industry and improving life standards are generating environmental challenges. The State of Qatar has witnessed unprecedented rapid economic growth, and fast development and urbanization during the last few decades, accompanied as usual, by heavy construction and mega scale projects, resulted in adverse environmental effects. Air pollution represent one of these major effects and challenges. Direct exposure to volatile organic compounds VOCs implies public health concern. Even low concentrations of VOCs have been associated with damage to the central nervous system (CNS). The CNS is the primary target organ for toluene toxicity in both humans and animals for acute (short-term) and chronic (long-term) exposures (HMDB, 2014). Benzene is a known human carcinogen and is linked to an increased risk of developing lymphatic and hematopoietic cancers, acute myelogenous leukemia, as well as chronic lymphocytic leukemia (EPA, 2004). Information regarding ambient VOCs exposure is limited in Qatar and in the whole Gulf region in terms of values and types of compounds; however, it can be expected that the concentration values are elevated as they are regarding the other combustion related components such as CO, NOX, SO2 and black carbon (Qatar Environment Statistics Annual Report, 2014). The ozone concentration is also often exceeding the limit value due to the intensive photochemical processes induced by the strong sun radiation and the presence of ozone precursors. The main sources of the critical VOC pollutants in the atmosphere- Benzene, Toluene, Ethylbenzene, and Xylenes- referred to as BTEX, are the motor vehicle exhausts, emissions from the use of solvents, and emissions from the chemical and petroleum industries. This study was an attempt to assess and evaluate the impact of traffic and nearby industry on the air quality of Doha by studying the most important combustion related volatile organic compounds such as BTEX, and atmospheric trace gases (NO, NO2, O3 and NH3). The research aims have been accomplished by conducting two sampling campaigns across the area of Greater Doha with 14 different locations at the main access roads and remote areas during two weeks sample collection period; from February 29, 2016 to March 15, 2016; and from March 16, 2016 to March 31 2016, to quantify the ambient air levels of these pollutants. Passive absorption (diffusion) tubes were used in this campaign because of their mobility, applicability and affordability for outdoor air sampling, as they are easy to handle and require cheap and user-friendly equipment (Buczynska, 2009). Concentrations from most components indicated hot spots roads at the south more than the north of Doha in which BTEX ranged from 7.68-40.5 μg/m3, NO from 7.97-170.4 μg/m3, NO2 from 41.5-105.5 μg/m3 and NH3 was ranged from 8.87-30.4 μg/m3. On the other hand, ground level ozone (O3) depleted at the air pollution hotspots showing higher concentrations at the northern part of the city with a range from 12.1-70.9 μg/m3. Among the samples, the maximum NO2 level was lower than Qatari environmental executive law of 150 μg/m3 on average period of 24-hours. Also, the maximum benzene concentration was 3.15 μg/m3 less than the standard of 5 μg/m3 established by European Community (EC). Visualization of the results has been performed using demonstration hotspot multilayers maps, overlaid in Google-Earth, showing the geographical distribution of the concentration of each individual component. The anticipated continuation of this research will be accomplished by increasing the sampling points and conductive more extensive survey in order to get more representative data with higher spatial resolution. The resulted air quality maps will be essential tools in the hands of policy and decision makers, as a contribution to the current efforts to improve air quality in urban areas. The authors would like to thank Qatar National Research Fund (QNRF) for funding and supporting this project under the National Priorities Research Program (NPRP) award number NPRP 8-202-3-043. Refreneces: Buczynska, A. J. (2009). Atmospheric BTEX-concentrations in an area with intensive street traffic. Atmospheric Environment, 311–318. Committee on Tropospheric Ozone, N. R. (1991). Rethinking the Ozone Problem in Urban and Regional Air Pollution. Washington, D.C.: NATIONAL ACADEMY PRESS. EPA. (2004). EPA Air Toxics. Retrieved from https://www.epa.gov/sites/production/files/2016-09/documents/toluene.pdf HMDB. (2014). Human Metabolome Database. Retrieved from http://www.hmdb.ca/metabolites/HMDB0001505
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Travel Time Estimation using Multivariate Regression Model
Authors: Khaliqur Rahman, Shoaib Mallick and Muhammad AsifAs it is known from the current research and studies that travel time of vehicles is the most reliable parameters to measure the cost of a link. Cost modeling of routes has many useful applications in dynamic route selection strategies e.g. route selection for emergency vehicles. Travel time of an individual vehicle passing a road segment is a function of many parameters which includes of road geometry, traffic flow characteristics, driver»s behaviors and region-specific rules and regulations, length of the segment, number of lanes, lane width, traffic flow, traffic volume and density, average speed of vehicles, vehicles composition and the ratio of turn movements on ramps. Moreover, the average travel time of vehicles on freeways is also dependent on some parameters that vary from country to country e.g. traffic regulations, driving rules, driver»s behavior and the construction of roads. Current mathematical models and simulation software»s lack the implementation of all these parameters and hence the results of these models are mostly different from the actual. The calibration of simulation software is always required to reduce this difference. The estimation of travel time using some numerical computation or simulation software»s is not reliable. This paper describes the modeling of travel time as a cost/metric of segments on a freeway. In it, regression models are used to evaluation the travel time for a throughway segment using traffic statistics acquired from field surveys. The validity of the models is explained with their statistical significance. Regression models are equally beneficial for any region if the data sets are quite large and enough parameters are included in the model. In regression analysis, the relationships among different variables are estimated. In it, different modeling techniques are used to find the relationship between dependent and independent variables. More precisely, the analysis helps to realize how the dependent variable changes with the variation of any of the independent variables keeping other variables fixed. In this work, statistical techniques i.e. regression modeling and analysis of variance (ANOVA) has been used to evaluate the impact of each independent variable (parameters) on the travel time. Finally, a multivariate regression model is used to approximate the time of travel. The estimated time is related to the actual travel time from the real field data and the model fitness is evaluated. Our dataset constitutes of four independent parameters and one dependent parameters. Independent variable (Inputs): 1 Length of the segment 2 No of lanes in the segment 3 Flow of traffic on the segment 4 Average Speed of vehicles on the segment Dependent variable (Response) 1 Travel Time Regression analysis has been used as a statistical technique to find the response variable (travel time). In this paper it is proposed to find the travel time for a particular connection using regression models applied to actual traffic data sets collected from field surveys. Real traffic data for several segments from different freeways has acquired and analyzed them using regression models. The probable travel time was compared with actual travel time for each segment of the highway and it was found that the estimation using regression models reveals the significant level of accuracy. R-Studio is being used in the statistical analysis of the data. We computed the regression equation for the estimation of travel time for all the given four parameters (distance, lanes, flow, speed) using coefficients, β0, β1, β2, β3 and β4. Figure1 shows the actual travel time of the vehicle and the estimated travel time which is obtained by the regression analysis.
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Indoor and Outdoor Air Pollution in Doha – cases of schools and residences
More LessThe World Health Organization (WHO) attributes air pollution to 1 in 8 deaths worldwide, where exposure to indoor air pollutants is a significant contributor to incidences of heart disease, respiratory problems, and cancer (WHO, 2014). Since people spend the major part of the day indoors - especially in Qatar -, indoor air quality (IAQ) is a significant factor affecting their overall pollutant exposure via the respiratory-inhalation pathway. IAQ is mainly determined by the geographical location of a building, its proximity to outdoor pollutant sources such as industry, construction activities, traffic or natural pollutant sources (e.g. desert sand particulates), as well as the building characteristics itself (building envelope, air tightness, ventilation/air conditioning system). Indoor sources like decoration and furniture, as well as indoor activities like cleaning and cooking also affect IAQ. Recently, the WHO ranked Qatar second position worldwide of countries with the highest ambient PM2.5 exposure (WHO, 2014). The issue can therefore be regarded as of great significance to public health for the citizens of Qatar, and therefore warrants scientific study and potential mitigation of excessive PM2.5 exposure. In particular, the young citizens of Qatar are especially susceptible to the impacts of PM2.5 inhalation due to their early stage of physiological development. A building can function as a protective shelter for poor outdoor air quality, but without a dedicated IAQ enhancement strategy, buildings may not automatically lead to a reduced indoor exposure to air pollutants, including PM2.5, as well as other potentially harmful pollutants including: oxides of nitrogen and sulphur (NO2, SO2); ozone (O3), natural radiation (radon, Rn); microorganisms (bacteria and fungal spores); a range of volatile organic compounds, and hydrocarbons. This study aimed to characterise IAQ of Qatar's indoor environments, with a particular focus on schools and residences with consideration of outdoor air quality (OAQ) conditions. Simultaneous IAQ/OAQ measurements have been conducted using established reference methods and sampling techniques specifically developed for IAQ studies. PM10, PM2.5 and ultrafine particle concentrations, aerosol size distribution and particle elemental composition have been measured. Volatile organic compounds, aldehydes, NO2, SO2 and O3 were monitored. CO2, temperature and relative humidity were also monitored, and the air exchange rate between indoor and outdoor environments has been assessed. Semi-volatile organic compounds, such as polycyclic aromatic hydrocarbons, phthalates and flame retardants have been quantified in order to identify specific sources of contamination as derived from combustion and/or building material emission sources. Three school classrooms and associated school-pupil homes were selected for conducting IAQ assessments in order to determine pupil exposure levels to air pollutants over a 24-hour period. Volunteers were equipped with personal exposure monitors for determining their location and activity-dependent air pollutant exposure levels. The first measurement campaign of the research project was conducted in May, 2017. Three classrooms were monitored and five residences, as well as the outdoor location in the school's garden. The results indicate that the indoor concentrations of VOCs, aldehydes and PAHs exceeded the outdoor levels, and that pollutants concentration in residences were consistently higher than in the school classrooms. In terms of particulate matter (PM2.5) the opposite trend was observed. The indoor PM2.5 levels were far lower than the reference outdoor concentration. Regarding the comparison of school class rooms and homes, the same trend as in the case of VOCs was observed. Namely, the PM2.5 levels in homes were consistently higher than in the school classrooms. Overall, the results show that indoor environments represent a protective shelter against the outdoor particulate air pollution ion Qatar. The indoor air quality is determined mainly by pollution sources indoors – particularly in residences due to the presence of more intensive and versatile emission sources – including furniture, decorations, use of air refreshers; as well as activity generated emissions by the inhabitants like cooking, cleaning, or smoking. The second measurement campaign will be conducted in December 2017, when new data will be collected under different seasonal conditions i.e. mild temperatures, where buildings typically have more ventilation with the outdoor environment, and where higher ingress of outdoor air pollution may be expected. The authors would like to thank Qatar National Research Fund (QNRF) for funding and supporting this project under the National Priorities Research Program (NPRP) award number NPRP 8-202-3-043.
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Simulation and Optimization of an LNG Plant Cold Section
Authors: Mary Anna Katebah, Mohamed Mamoon Hussein and Easa Ismail AlmuslehSimulation and Optimization of an LNG Plant Cold Section Mary Anna Katebah, Mohamed Mamoon Hussein, Easa I. Almusleh* Chemical engineering department, Qatar University Global energy demands are expected to rise by almost 30% in the next 20 years, with fossil fuels being the primary energy sources. The combustion of fossil fuels yields significant amounts of greenhouse gas emissions, predominantly CO2. Compared to its alternatives (coal and crude oil), natural gas is preferred primarily due to its cleaner burning. The most profitable method of transporting natural gas from the source of production is as liquefied natural gas (LNG). However, LNG plants are associated with relatively large energy demands (mainly compression power) that are costly and result in significant levels of CO2 emissions. Qatar is the largest LNG supplier world-wide, and the plans of increasing production place utmost importance on enhancing the efficiency of LNG plants. With current production of almost 78 million tons per annual (MTA), significant benefits, such as improved economics and lower CO2 emissions, can be achieved even with small efficiency improvements. It is also noteworthy that, for a given power consumption, higher efficiencies can potentially result in more production volumes. Therefore, optimization of LNG processes would assist the country in achieving the aspirations of the Qatar National Vision 2030 by sustaining both economic prosperity and the environment for future generations. Within the LNG chain, more than 75% of the CO2 emissions emanate in the processing plant, where nearly 80% of those emissions are sourced in the cold section of the plant which comprises of the natural gas liquids (NGL) recovery system, the liquefaction process, and the helium extraction and nitrogen removal units. Various natural gas liquefaction cycles exist that employ either pure refrigerant in cascade cycles, multi-pressure cycles, or mixed refrigerant cycles. Among all the available cycles, the propane pre-cooled mixed refrigerant (C3MR) system is the leading one in the LNG industry. Therefore, this research focuses on decreasing the energy consumption of C3MR and NGL recovery system with helium extraction (producing approximately 60 mol% crude helium) and nitrogen rejection units. Initially, a base-case model was developed for the cold section using Aspen PlusTM, a steady-state process simulation and optimization software. A degree of freedom analysis was carried out on the model to identify the operating variables available for optimization. This step also serves to identify the operational and design constraints. Next, a sensitivity analysis was conducted on the variables to construct the operating windows one may operate in and get reduced energy consumption. Parameters that were studied include: scrub column reflux and pressure, mixed refrigerant (MR) composition, propane evaporating pressures, LNG temperature (leaving the main heat exchanger), and helium extraction and nitrogen removal temperature and pressure values. Finally, sequential quadratic programming (SQP) optimization technique was employed to find optimal values for the operating variables that will result in global minimum energy consumption. In addition to this rigorous optimization approach, we have developed an effective shortcut method that can be used for optimization with minimum effort. The method was evaluated and found to be suitable for LNG and other cooling applications. Additionally, an exergy analysis was conducted before and after optimization to quantify the reduction in lost work for main process equipment as a result of the optimization. After investigating optimization options with minimal implementation costs, retrofitting options will be studied to further enhance the process. Simulation of the cold section was conducted for the production of almost 3.65 MTA of LNG. Sweet, dehydrated natural gas at 21°C and 66 bar was pre-cooled by the propane cycle to around − 27 °C before entering a scrub column (i.e. distillation column) that separated the natural gas from the NGL's. Almost 12 thousand barrel/day of NGLs were produced and sent to a fractionation unit to separate ethane, propane and butane. Heavy hydrocarbons, primarily condensate (C5+) leaving the fractionation unit, can be either sold or sent to a close by refinery for further processing. The separated natural gas stream was further cooled and liquefied in the main cryogenic heat exchanger (MCHE) to temperatures near − 140°C. The cooling in the MCHE was supplied by the mixed refrigerant, which was pre-cooled by the propane cycle. LNG then entered the helium extraction (producing almost 60 mol% crude helium) and nitrogen removal units to obtain desired LNG specifications. Final LNG product comprised of 0.7 mol% nitrogen, 90.7 mol% methane, 5.6 mol% ethane, 2 mol% propane, 0.92 mol% butanes, at a temperature and gross heating value (GHV) of approximately − 161°C and 11.5 respectively. Simulation results showed that for the production of 3.6 MTA LNG, the cold section would require a total of around 131 MW of compression power. Main sensitivity analysis results showed that the mixed refrigerant composition was a key parameter in the cycle's performance. Other primary parameters affecting the energy consumption include the propane cycle's evaporation pressures and flowrates. Using the short cut method, optimization revealed that optimized MR composition resulted in almost 10% MR compression power and 6% plant operating cost savings, whereas new intermediate propane evaporation pressures, identified using detailed simulation, and flowrates decreased the propane compression power and operating costs by around 3.6%, and 2%, respectively. *Corresponding author. +974 44034148 E-mail address: E-mail: [email protected] (E. Al-musleh).
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Screening of Fresh water and Sea water Microalgae strains from Qatar for feed supplement production
The worldwide continuous increasing of population provokes an increasing awareness about the food security. Qatar is one of the first countries establishing a Food Security Strategy Program to satisfy the demand of food and feed. Microalgae is considered as one of the most promising solution based on its ability to produce the essential elements needed for food and feed such as lipids, carbohydrates, proteins... In Qatar University, a diverse collection of Microalgae and Cyanobacteria strains isolated from different environments was established (QUCCCM). Microalgae, These photosynthetic microorganisms are capable of converting solar energy into useful compounds. Microalgae accumulate several kinds of metabolites such as proteins (6-52%), lipids (7-23%), carbohydrates (5-23%). In addition, microalgae produce have the ability to produce high-value metabolites. The aim of our work was to screen the QUCCCM and identify potential strains with high nutritional value for use as feed for poultry and livestock. In this study, Microalgal isolates belonging to 12 different species were investigated for their eligibility to be used as a feed. All strains were cultivated over a period of 10 to15 days depending on species. Optical Density and Dry weights were recorded every three days to follow the algal Growth. The results showed the presence of three categories of isolates (fast, medium and slow growing). Among them, the species Chlamydomonas sp. presented the highest growth rate (μ) with 0.89day − 1 ± 0.27 and a doubling time of 1.28/ day. Based on this result, the fast-growing strains were subjected to metabolite investigations in terms of lipids, proteins, carbohydrates, amino acids and Fatty acids to select the ideal strain(s) presenting high growth rate along with metabolites valuable for algae-based feed supplement. The highest protein and Lipid content was observed in the case of a freshwater strain belonging to the Mychonastes sp.with ∼ 50% w/w and 40.7% ± 0.015 respectively. Carbohydrates were seen highest in Chlorococcum sp.with a value of 30% ± 0.009%. Considering the marine strains, the isolates had a similar range of protein, Lipids and Carbohydrates content of (22%-34%), (32%-39%) and (8%-20%) respectively. Based on this study, one marine strain (Pichochloris sp.) having 33% ± 0.021 content of protein and 32.7% ± 0.036 as lipid, and one freshwater (Mychonastes sp.) holding the highest amount of metabolites were selected for deeply investigations in terms of FAME and Amino acid profiling which are crucial parameters that determine the feed quality. The results showed the presence of different essential Amino acids in the total protein fraction. Fatty acid profiling comprised saturated and unsaturated fats for all strains; most of them being rich with C18:0; C16:0 and C16:3. For the selected strains, the metabolite content during the growth period was followed by sampling every 3 days in order to identify the stage having high productivity and rich metabolite content. The analysis of the isolates showed an increase in the production of each metabolite during the growth, wherein lipids and protein amounts are relatively high while carbohydrates were comparatively low. These two selected strains will be improved in terms of lipid and protein production using media and salinity stress in order to enhance the production of essential nutrients such as omegas, amino acids and used for animal bioassay. In Conclusion, this study showed the existence of a diverse and rich collection of valuable strains with important metabolites that can support the country's food security program, by providing microalgae to supplement animal feed. Additionally, the potential candidates can be used for commercial applications.
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Levels of Airborne Bacteria in a School Classroom Environment in Doha Qatar
More LessAirborne bacteria represent a potential risk to human health upon inhalation in both outdoor and indoor environments. Outdoors, bacteria may be derived from a variety of sources including soils, vegetation and animals, whilst indoors sources include both healthy and infected individuals, as well as pets, furnishings and food sources. The aim of this study was to investigate the quantity and size distribution of airborne bacteria inside a school classroom, as well as the outdoor environment, in Doha, Qatar. Air samples were collected from the indoor classroom and outdoor environment at the German International School in the south of Doha, Qatar during two separate sampling periods in 2017 i.e. summer time (15 June) and autumn time (17 October). An Anderson Six-Stage Impactor was used to collect airborne bacteria. The impactor aerodynamically sizes collected microbes in an airstream over six stages (i.e. 7 < ; 7.0 to 4.7; 4.7 to 3.3; 3.3 to 2.1; 2.1 to 1.1; and 1.1 to 0.65 μm diameter, respectively). Bacteria in each size stage are collected on nutrient agar (NA) plates in the impactor. Air samples were collected in triplicate both indoors and outdoors prior to commencement of class at 6:30 AM, and immediately after end of classes at 2:30 PM. Each sample was collected over a 5 minutes period at an airflow rate of 28.3 liters of air/minute i.e. total 141.5 liters of air collected per sample. After sampling, NA plates were then incubated for 24 hours at 37°C. After incubation the number of colony forming units (CFU) of bacteria on the NA plates were counted, and the average of triplicate samples for the morning and afternoon samples were calculated as the mean number of airborne bacteria per cubic meter of air (CFU/m3). The prevalence and concentration of bacteria varied both spatially (indoors versus outdoors), and temporally (morning versus afternoon). In both sample periods i.e. 15 June 2017 and 17 October 2017, the levels of airborne bacteria in classroom air were lowest in the morning i.e. before class (a maximum 204 CFU/m3 in June, and a maximum 35 CFU/m3 in October) than in the afternoon after class (a maximum 348 CFU/m3 in June, and a maximum 543 CFU/m3 in October). As the classroom was continuously occupied between the morning and afternoon, then human influence is the most likely factor affecting prevailing CFU levels. Other factors likely affecting CFU levels may include: airflow dynamics and exchange between the indoor and outdoor environment; the influence of the classroom air-conditioning and ventilation system (positive or negative) and; the presence of non-human bacterial sources in the classroom (food debris, carpeting, soft furnishings etc.). Outdoor air samples showed the opposite profile to the classroom, where morning samples had higher numbers of airborne bacteria in the morning (a maximum 640 CFU/m3 in June, and a maximum 111 CFU/m3 in October) compared to the afternoon samples (a maximum 299 CFU/m3 in June, and a maximum 82 CFU/m3 in October). This contrast supports the indication that airborne bacteria in the classroom are derived from internal sources rather than as a result of infiltration of bacteria from outside. The most prevalent size range of airborne bacteria present in the classroom were in the 1.1- 3.3 μm diameter range for both sample periods (June and October). Such bacteria are typically associated with aerial emission from individuals via coughing, sneezing, and exhalation, and typically represent the greatest potential pathogenic risk in terms of re-inhalation and penetration into the respiratory-lung system. Qatar does not currently have occupational health guidelines for airborne bacteria, but guidelines are available for other countries where similar work has been conducted by the project LPI, Professor Obbard – notably in Singapore. Here, the recommended guideline level for total airborne microbes in indoor air is 500 CFU/m3 for both airborne bacteria and fungal spores. The measurement of 543 CFU/m3 measured for bacteria alone in classroom air in Doha (October 2017), suggests that classroom air quality can exceed such health guidelines for both students and teachers - particularly as the most prevalent size range of the airborne bacteria are in the size range for penetration into the respiratory-lung system. The results of the study show that levels of airborne bacteria in classrooms in Doha become elevated over the course of the teaching day – most likely due to the presence of teachers and students that serve as natural reservoirs of bacteria (both non-pathogenic and pathogenic). Inadequate ventilation of the classroom and/or the air conditioning serving as a source of bacteria could also be a contributor to elevated levels of airborne bacteria in the school classroom. It is also clear that the size distribution of the airborne bacteria is predominated by bacteria in the smaller size ranges that have the greatest potential to penetrate the respiratory-lung system. In the event that airborne pathogenic bacteria are present (perhaps from aerolized from an infected person via coughing, sneezing) then this represents an increased infection risk. The study is on-going, and will investigate methods to reduce levels of airborne bacteria in the classroom via improved ventilation, air-exchange and/or filtration.
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Characterization of Commercial Reverse Osmosis and Nanofiltration Membranes for Membrane Fouling
Membrane Filtration technique is being accepted worldwide as an environment friendly and energy efficient technique in Desalination Industry as compared to Thermal Desalination techniques. However, the performance of membranes which include permeate flux and rejection is affected by the membrane fouling. The properties of membrane and surface features such as porous structure, hydrophilicity/hydrophobicity charge, polymer characteristics, surface roughness determine the fouling potential of the membrane. The hydrophilic and smooth membrane surface is usually considered desirable in tackling membrane fouling issues. Therefore, many studies have focused on to enhance surface characteristics of membranes by surface coating with polymers and nanomaterials. Since, membrane coating is not done during fabrication of the most commercially available membranes, therefore, it is also important to determine the surface features of the commercially available membranes to investigate their membrane fouling potential. Thus, the objectives of this study were (1) to perform membrane surface characterization of commercial Reverse Osmosis (RO) and Nanofiltration (NF) membranes using techniques such as SEM, AFM, FTIR and XPS; (2) to measure hydrophilicity/hydrophobicity of commercial RO and NF membranes through water contact angle measurement using sessile drop method and (3) to measure the flux and percentage rejection of NF and RO membranes using Dead end filtration technique. Here, the characterization of membrane surface in terms of surface roughness, using SEM and AFM, showed that the commercial RO membrane had more ridge and valley structures and higher average surface roughness i.e. 71.24 nm as compared to NF membranes (6.63 nm). In addition, water contact angle measurements showed that the NF membrane was more hydrophilic as compared to RO membrane. The average contact angle found for RO membrane was 59.94°. On the other hand, it was observed that NF membrane is extremely hydrophilic in nature. Due to which, contact angle value was not obtained for most of the runs. The droplet could diffuse in less than 5 seconds. In addition, the dead-end filtration experiments showed that the RO membrane had much lower flux as compared to NF membrane. This can be associated with the pore structure of these membranes. Since, the NF membrane has porous structure, in oppose to RO membrane, the flux of the NF membrane is usually higher than the RO membranes. As the membrane surface roughness and hydrophobicity makes it more susceptible to the fouling leading to reduction in membrane flux and performance, it can be concluded from this study that there is a need for surface coating of RO membrane with suitable nanomaterials such as graphene oxide to improve its hydrophilicity and surface smoothness. This will eventually make the membrane more resistant to membrane fouling and will establish the use of membrane filtration technique in desalination industry in Qatar in the future. Microorganisms have been isolated from Gulf sea water, identified and differentiated and are being used to study the biofouling of RO and NF membranes, that would be coated to limit the fouling problems. Acknowledgement: This research was made possible by NPRP grant # [9-318-1-064] from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the author[s].
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Reconstruction of Ribosomal RNA Genes from Metagenomic Data obtained from oilgas pipelines in Qatar
More LessQatar's economic emergence is influenced in great part by its gas reservoirs. Hence, gas processing is considered as one of the major steps to aid Qatar in its transition towards a more diversified, prospered and innovative economy. However, there is a need for research to assess the quality of water in the cooling system used in the manufacture of petroleum products. Thus, assessing water quality can help complement the technologies used for gas processing and address the challenges facing gas industries. One of these problems is pipeline anaerobic iron corrosion induced by the activity of environmental microorganism. Such microbially influenced corrosion (MIC) has various technical and economic implications that have major effects on gas and oil processing. It has been suggested that the presence of sulfur-reducing bacteria (SRB) in the cooling water in oil and gas pipeline is considered as the main culprit of such corrosions due to the pipeline anoxic conditions. Thus, examining water security, which is the aversion of water-related risks, in oil and gas industry is needed. Such risks may include disrupted operations and economic losses. Thus, there is a need to improve water use efficiency in the oil industry to improve oil and gas production and the process of shipping it to different destinations. Hence, our research aims to obtain water samples from different points of the oil-gas pipelines in Qatar and carry out microbial classification. More specifically, the aim of our research is to obtain reverse transcription polymerase chain reaction (RT-PCR) sequenced DNA data using the Ion Torrent method and analyze them. First, multiple samples containing various bacterial species were obtained from different points of the oil-gas pipelines in Qatar. Then RT-PCR was carried out on these samples using specific primers that can hybridize to the conserved regions of the 16S ribosomal RNA region. The PCR amplicons were then sequenced using the Ion Torrent device. The next step is to reconstruct the 16S ribosomal RNA (rRNA) region using the computational genomics tool, SPAdes, and aim for a good coverage and a good alignment score. SPAdes is a genomic assembler that uses iterative mapping of short reads and blast them against reference sequences to reconstruct 16S rRNA genes. The reconstructed regions would be from different bacterial species and each bacteria would have its own hypervariable region that serves as a fingerprint. Hence, the reconstructed 16S ribosomal RNA (rRNA) sequences are considered reliable markers for the taxonomic classification and phylogenetic analysis of bacteria. Eventually, the data is classified and filtered using Ribosomal Database Project (RDP) classifier 2.3, which is then followed by manual extraction, categorization and evaluation. RDP is a naive Bayesian classifier that can rapidly classify bacterial 16S rRNA sequences into the new higher-order taxonomy proposed in Bergey's Taxonomic Outline of the Prokaryotes. This online classifier provides taxonomic assignments from domain to genus.Our results show that the water samples contain high percentage of the sulfur-reducing bacteria (SRB) when compared to the percentage of other microbes in the water samples. This emphasizes on the necessity to improve water security of the oil-gas cooling system by reducing the percentage of such bacteria. Hence, one of the potential future direction of this project is to identify bacteriophages that have the ability to eliminate the sulfur reducing bacteria from the cooling water system and thus reduce the chances of water contamination.
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Qatari Oil Revenue and Economic development
More LessQatar focused on economic development since independence in 1971. The government has over the time established many developments oriented institutions and authorities, including the Supreme Planning Council, General Secretariat for Development Planning and Ministry of Development Planning and Statistics. Since the launch of QNV 2030 in 2008 with its four pillars (human development, social development, economic development and environmental development), this vision aimed to change the face of life in Qatar. Qatar is upgrading its speculation and development systems with indications of recuperation in worldwide markets in 2017. New patterns keep on emerging crosswise over esteem chain influencing supply, request and speculation situations in the nation. Both conventional players and new participants are reevaluating their arranged undertakings with updated estimates. As Qatar and worldwide markets move towards rebalancing, this article gives definite bits of knowledge into basic short and long haul factors set to shape the eventual fate of Qatar oil and gas markets. This work as a necessary manual for organizations wanting to extend and put resources into Qatar oil and gas advertises in close to medium term future. Openings and difficulties of growing new undertakings, evolving supply-request situations, development in developing markets, approach bolsters, new supplies and request sections, venture benchmarking are talked about in the exploration. For Qatar, gas costs are considerably more imperative than oil costs in light of the fact that the estimation of gas sends out surpass that of oil trades. The estimation of LNG sends out surpassed the estimation of all other hydrocarbon items in 2015, speaking to roughly 46% of aggregate ware trades. Around a fourth of Qatar»s fares of LNG is sold at spot conveyance costs, and the rest is sold as per contracts identified with oil costs (with a deferral of a half year). Concerning the dissemination of LNG sends out, in 2015, 66% were sent out to Asia, where higher costs win. Global LNG costs dropped amid the most recent a half year because of creation surplus in the area. Qatar has kept up its creation limit since 2011, however new fares from Australia and the Assembled States have started to develop. Since the vast majority of Australia»s fares goes to Asia and as Japan resumes operation of certain atomic plants, costs in Japan saw the best decay however are as yet the most noteworthy in the locale. Unrefined petroleum costs incorporating traditions charges in Japan diminished by 40.1% between November 1, 2015 and May 1, 2016. Costs related to the American Henry Center just diminished by 8.5% in a similar period. For the most part, in the US, where most gas is sold at spot costs, bring down costs win, while Japan has the most astounding costs since gas is sold by method for long haul fates related to rough costs including custom expenses. Given the abundance in delivery limit and the expected wealth in LNG supplies, Qatar is creating and restoring its showcasing strategy with a specific end goal to ensure it offers in the market, particularly supporting long haul supply assentions for LNG trades. Because of the lower allure of LNG costs and its foreseen opulence, the World Monetary Standpoint report issued by the IMF in April, 2016, tempered its desires at gaseous petrol normal costs in 2016 (the weighted normal cost in the Japanese, American and European markets), by 10.8% against a similar report»s estimate in October 2015. It is additionally conjectured value steadiness on an extensive scale in 2017 and 2018. Economy in Qatar is relied upon to stay versatile in 2017, regardless of a frustrating Gross domestic product development of 2.7% in the primary quarter (QoQ), after a 4.1% development in the last quarter of 2016. Swelling should level off in 2017. Be that as it may, costs are diminishing for lodging, amusement and eateries, which could cultivate utilization. In any case, the presentation of a uniform 5% VAT rate over all GCC nations, endorsed on May, third 2017, is relied upon to build costs subsequent to being actualized in 2018. The oil and gas segments, experiencing the fall in vitality costs, were working in the red in 2016, however they should help bolster development in 2017 with the begin of creation at the Barzan office (increment fluid gas generation by 21%). The non-oil and gas parts were dynamic in 2016, and they will keep on being, driven by development (+11.7% QoQ in the main quarter of 2017) and the administrations divisions. Development segment stays one of the main recipients of the Qatari government»s speculation arrangement for the FIFA World Container 2022. In spite of the fact that a ban has been forced on new undertakings, officially planned speculations are significant and assessed at what might as well be called nearly USD 180 billion. The administrations area (money related administrations, property and broadcast communications) should see solid development in 2017. Qatar is right now experiencing gigantic change under the rubric of the 2030 National Vision, which intends to build up a propelled, learning based, and enhanced economy, no longer dependent on the hydrocarbon area. The administration is intensely associated with Qatar»s economy, in spite of the fact that it firmly energizes private interest in numerous areas. Interests in different parts including medicinal services, instruction, tourism and money related administrations, among others,. The principle monetary boosts in Qatar are oil, gas, and related enterprises, specifically the advancement of the North Field, the biggest non-related gaseous petrol field on the planet. Qatar»s condensed flammable gas (LNG) industry has pulled in several billions of dollars in remote speculation and made Qatar the world»s biggest exporter of LNG are relied upon to offer more prominent open doors for outside venture. Qatar»s LNG conveyance cost is about $5.20/mBtu, which is near the Russian pipeline gas breakeven cost, yet $2 to $3 underneath full-cycle cost for US LNG at the present Henry Center point costs of about $3/mBtu. This implies at current costs, US LNG makers could take care of their peripheral expenses yet not long haul breakeven costs. «With its great reputation of LNG venture execution and the co-creation of condensate and LPG from the North Field, Qatar is the most minimal cost LNG maker on the planet. As of now, the seven parts concentrating on those are anticipated to have a general positive effect on the social and financial way of life in Qatar. These areas are horticulture, training, medicinal services, mechanical improvement, domesticated animals, fishery, and tourism.
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Comprehensive Assessment of Resin Systems as a Combined Solution for Well Integrity Challenge and Unwanted Fluid Shutoff in Carbonate Reservoirs
More LessThe petroleum industry usually uses class G cement when it comes to cementing jobs. However, that was the only option before, and because of that many issues came with it. Indeed, in the Middle Eastern region as well as the rest of the world, wellbore integrity is always a reason for concern. If wellbore integrity is not guaranteed, then production or drilling operations would be done under very unsafer circumstances. In order to fix certain leaks or cracks found in the well, resin cement can be used in order to prevent any interaction between the wellbore fluids and the formation fluids. Because of its elasticity and high compressive strenght resistance, the resin will fill in the fracture or space perfectly and seal it off thus preventing any future issues. An example of that would be when they used resin cement in the Utica shale formations where annular pressure buildup was faced due to a fracture found in the casing. The pressure buildup disappeared completely after they had applied resin cement into the fracture. It was also used to solve a combo problem when the operator was producing from Polish shale. Indeed, the problem was that they wanted to fracture the formation in order to improve productivity, however by fracking the formation, they would also damage the well and put the well into danger. In order to preserve wellbore integrity, the parts in the well were repaired by injecting resin cement in areas where the casing wasn>t well cemented. The operator company was the able to frac the formation with no wellbore integrity. Similarly, resin cement can also be used to abandon a well. Indeed, in order to perform a good abandonment, one major aspect that is focused on is that not pressure is bled off from the well. However, when gas is present, it sometimes keeps leaking despite the cement there. Which is where resin cement comes in hand. Because of its unique properties, the resin cement will be able to seal off the well completely with no issues due to its elasticity and how it sets. Other than resin cement being great to use as a seal, it also has a very high compressive and tensile strength compared to normal class G cement.We had to run several different tests to look at the different aspects it withheld. Thus, the resin was put through (transit time testing, temperature, compressive strength, acoustic impedance, and finally a crush test). To undergo all these tests there was a process that had to be followed so that all of our results were under API standard and were obtained in a safe manner.This research is aimed at seiing how resin cement as well as the mix of resin with class G cement can improve well integrity as well as combined solution for unwanted fluid shut-off in the Middle Eastern region, i.e. for carbonates reservoir and under typical reservoir temperatures and pressures found in this region. Through these results, we will be able to assess the application that can be used for any remedial jobs no matter what the issue and how great of a seal it can be. All of this will be seen through its enhanced properties.
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Novel Control Algorithm for control of qZSI as Front – End Converter during nonsunlight hours
Authors: Rahman Syed, Meraj Mohammad, Iqbal Atif and Haitham Abu-RubDegrading effect of energy generation from fossil fuel are extensively discussed and debated leading to paradigm shift to renewable energy generation. Energy generation from PV panels is the best alternative for state of Qatar which gets abundant sunlight throughout the year. Development of energy generation from PV panels helps in achieving the notion of “Energy Security”. Energy security refers to availability of reliable, cheap and quality power for consumption from customer point of view. Development in power electronics helps in achieving this idea by developing and operating converters circuits with good efficiency, efficacy, reliable, robust and free from maintenance. Encouraging the nurture and development of local energy suppliers will help in minimizing the cost of installation and maintenance. Including these economic constraints in the design of converters has become a crucial factor in developing industry oriented products through academic research. Suitability of several power converters for synchronizing the power generated from PV panels to utility grid. Recently developed Impedance source based converters are highly suitable for synchronizing the power generated from renewable energy to the utility grid. They eliminate the need for extra dc-dc converter by boosting the input voltage supplied from PV panels. Impedance source based converters are categorized as: Z Source Inverter and quasi Z Source Inverter (qZSI). qZSI is preferred due to its higher performance and continuous input current. Several methods are discussed in the literature to achieve boosting of input voltage. Inverter control requires modification in conventional Sine-Triangle compared based PWM. Operation of qZSI at different MPPT algorithms is also discussed. Cascaded qZSI operation to achieve higher power rating are also discussed. Implementation of advanced control techniques such as Model predictive control is also presented. Energy efficient qZSI achieved through different methods are also discussed. This paper presents novel control algorithm for control of qZSI as Front-End Converter (FEC) during non-sunshine hours. During sunshine hours, qZSI is controlled to inject active and reactive power into the grid. In absence of sunlight, qZSI can be operated as FEC to control reactive power management with the utility grid. To validate the proposed control algorithm, simulation results are presented for grid-connected qZSI powered from solar panel as shown in Fig. 1. Simulation results are formulated into following three sections: (a) Control of qZSI for active and reactive power management, (b) Transient response for qZSI to FEC transition and (c) Control of FEC for reactive power management.Control Algorithm: Control algorithm must satisfy the following requirements: a) When controlled as qZSI, i) Boosting of input voltage must be controlled to achieve the desired output rms voltage ii) Current injected into the grid can be at any power factor – unity, lagging or leading. b) Smooth transition from qZSI to FEC. c) When operated as FEC, i) DC Bus Voltage must be maintained constant and ii) Controlled reactive power management must be achieved. Proposed control algorithm is as shown in Fig. 2. It consists of two types of control blocks. Control blocks which are specific to a type of control algorithm and other which are common for both. Converter reference voltage generation and conventional Sine – Triangle comparison is common to control algorithms of both the inverters. For control of the inverter as qZSI, condition of Vin>Vth must be satisfied which means voltage generated from PV panels is sufficient for grid synchronization. During this mode, S1 and S3 are closed and S2 is opened. qZSI control consists of grid current control and dc bus voltage (Vdc) control. Active and reactive power demand is converted to current proportional and passed through PI controller to generate the converter voltage reference. DC Bus voltage controller gives the shoot-through duty cycle (D). Based on the value of D, shoot-through pulses are ORed with conventional pulses generated by sine-triangle comparison. When Vin>Vth is not satisfied, then the position of relays is changed. S1 and S3 are opened and S2 is closed. Due to this, the solar panel is disconnected from the inverter. The dc bus formed due to series connection of C1 and C2 must be controlled from the grid voltage. The dedicated control block shown in Fig. 2 for FEC generates the active current reference and add it up with required reactive current reference to give the grid current reference. This is passed through PI Controller to give the converter voltage reference. Conventional Sine-triangle comparison is performed to generate switching pulses.SIMULATION RESULTS To verify the control algorithm, the simulation results are shown in Fig. 3. Up to t = 2 sec, the inverter is operated as qZSI injecting controlled active power into the grid. At t = 2 sec, the relays are operated disconnecting the solar panel at the input and now inverter is controlled as FEC. Due to this, the dc bus voltage shoots up which is controlled with the control algorithm. To maintain the dc bus voltage, active current is drawn from the grid. Active current drawn is negligible compared to reactive power managed with the utility grid. Figure 3(a) shows the response of dc bus tracking during the operation. In qZSI mode, active power injection is controlled as shown in Fig. 3(b) and Fig. 3(c). When the inverter is controlled as FEC, reactive power absorbed and supplied are shown in Fig. 3(d) and Fig. 3(e) respectively.
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Energy Metabolism Analysis in Qatar From Socioeconomic Dimensions
Authors: Sami G. Al-GHamdi and Abdulrahman AL-TamimiDue to rapid urban development and increasing population, urban areas are facing more challenges in the area of sustainable development. In order to make sure that these cities are moving toward sustainable development, it is very important to highlight the human activities as significant elements in terms of energy metabolism. This paper employed the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) approach to analyze the energy metabolic pattern of Qatar from ecological, social, and economic dimensions. MuSIASEM has been introduced for the first time late 90’s, and it is trying to answer the questions of how and why humans use resources? how this use depends on and affects the stability of the ecosystems embedding the society? Therefore, this study aimed to track and record level of energy sustainability in Qatar, describe and analyze the energy and GDP flow in Qatar using MuSIASEM. Energy consumption per capita in Qatar reached 17,418 kg of oil equivalent in 2014, while the rate in US is 6793 kg of oil equivalent. That makes Qatar one of the biggest energy consumer around the world, and that's has negative impacts on our society e.g., CO2 emissions per Capita in Qatar reached 37.78 metric tons in 2013. A case study of Qatar was considered instead of the capital and largest city (Doha) because all the urban areas and human activities in Qatar are connected with Doha, especially with the small area of Qatar 11,627 km2. Thus, Qatar is the suitable study's area compared with the mega cities around the world. In addition, all the previous studies which used MuSIASEM as methodology focused on countries which import energy, but Qatar exports and produces energy, and that makes the study unique and valuable. The study investigated historical pattern changes of human activities in Qatar with focusing on working hours in line with Gross Domestic Product, then evaluated the possible results, so that the detailed metabolic patterns can be identified and appropriate development policies can be prepared to help decision makers with the implementation of Qatar Vision 2030 which consider sustainable development as fundamental pillar. The results investigated the correlation and interactions between Gross Domestic Product, added value, human activities, energy consumption, energy intensity, exosmotic energy metabolism, and future economic transition in Qatar. To make the results systematic and organized, it have been subdivided hierarchy into three levels: Level n studied The whole society of Qatar, Level n-1 studied both of consumptive sector (hose hold) and productive sector (work sector), Level n-2 focused on the subdivisions of work sectors and house hold typologies. Speaking of data resources, the economic and social data of study have been provided by Ministry of Statistics and Development Planning, While the electrical data has been provided by Qatar General Electricity and Water Corporation (KAHRAMA). World Bank, and International Energy Agency (IEA) provided all the date related to energy consumption. Other data like human time, energy intensity, and exosmotic metabolic rate have been calculated through some equations which will be explained in the study.
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Detailed exergy analysis of full scale LNG plant
Authors: Essa Al-Musleh, Mohamed Hussein, Mary Katebah and Zineb BouabidiSustainability is one of the major challenges faced by the industrial sector as it is driven by both environmental and economic factors. Energy demands are increasing and, to date, most of the supply is generated via fossil-fuel combustion, such as coal, gas or oil. However, these processes release greenhouse gases, mainly CO2, that contribute to global warming and other environmental issues. Of the three fossil fuels, for a given amount of energy released, natural gas produces the least amount of CO2, making it the most vital energy source. The most practical way of transporting this natural gas over long distances is via liquefaction. However liquefied natural gas (LNG) plants consume substantial amounts of energy; thus, releasing significant amount of CO2. Therefore, enhancing the efficiencies of LNG plants is essential especially for large producer such as Qatar. As of today, Qatar is the largest producer of LNG in the world, with a capacity of near 78 Million tons per annual (MTA). Since the LNG industry in Qatar is a major contributor to the country's economy and development, there is a continuous need to improve and optimize existing LNG systems to extract more value out of them. Optimization of such complex system is; however, not a straight forward technique requiring different expertise ranging from engineering/process oriented insights to mathematical and thermodynamics techniques. Thus, it is deemed essential to identify plant sections that must be given priorities for optimization. This requires quantifying losses and efficiencies and one of the effective tools is exergy analysis. Identifying the areas of exergy losses within LNG plants emphasizes the areas where optimization is necessary. This project aims to foster the transition to cleaner LNG plants that operate more efficiently, in terms of energy consumption, towards an active contribution to the protection of the environment. The primary focus of the study is to identify exergy losses across a baseload LNG plant producing more than 3 MTA of LNG. In this research, a rigorous and detailed exergy analysis was performed on an entire actual LNG process that was simulated using ProMax® and Aspen Plus® simulation software. In order to carry out the thermodynamic analysis, exergy loss across each component of the entire plant was determined. Exergy analysis was not limited to process units, as it was extended to quantify exergy loss across the utility section. Results revealed that the main contributors to the exergy loss are the utility section, accounting for 49% of the total exergy loss. Within the LNG process, significant amounts of losses were found to occur in the liquefaction, sweetening and sulfur recovery units; corresponding for 37%, 30% and 21% of the total exergy loss, respectively. Components responsible for the highest exergy consumption were also highlighted, with the main consumers being the compressors and their drivers, stream generators, LNG flashing and storage, columns (absorbers, distillations) and heat exchangers. The contribution to the total exergy loss provided some insight on locations where improvements are needed to translate into more environmental and energy benefits. For example, most of the losses within the liquefaction section was attributed to compressors and the drivers responsible for the generation of the required shaft work; almost 19 MW exergy loss in the gas turbine corresponds to 1 MW exergy loss in the associated compressor. Thus, significant energy savings can be achieved via minimizing the compression energy. *Corresponding author. +974 44034148 Eamil address: [email protected] (E. Al-musleh) References [1] «2016 World LNG Report - International Gas Union,» Chevron, USA2016, Available: www.igu.org/download/file/fid/2123.
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Designing piezoelectric nanogenerator from PVDFHFP nanocomposite fibers containing cellulose nanocrystals and Fedoped ZnO
More LessSelf-powering devices harvest energy from the environment and perform based on a maintenance free approach. These materials are of utmost significance as they solve the problems associated with the energy crisis and management, to greater extends. Advances in material science and the design of various polymer nanocomposites developed many self-powering devices that are flexible, sensitive, less power consuming and of low cost. The semi-crystalline polymer, poly vinylidene fluoride (PVDF) and its co-polymers are notable for mechanical energy harvesting because of the typical crystalline phases in their structure. Various nanoparticles are added to such polymers to enhance their dielectric and piezoelectric properties as well. Since the alignment of crystalline phases improve the energy harvesting properties, techniques such as electrical poling are practiced to enhance their applicability. Among various alignment procedures, electrospinning stands as unique since the high voltage applied to the polymer solution generates nanofiber scaffolds in perfect alignments. The present work aims to develop electrospun composite fibers in nano-dimensions for designing self-powering nanogenerators. The co-polymer of PVDF, polyvinylidene fluoride hexa fluoropropylene (PVDF-HFP) was used as the base polymer and the iron-doped zinc oxide (Fe-ZnO) and cellulose nanocrystals (CNC) as the filler reinforcements. Fe-ZnO nanostructures were obtained by hydrothermal synthesis method from the ZnO precursor, while the CNC were synthesized following the acid hydrolysis of cellulose microfibers. The optimized concentration of 20 wt.% was used for obtaining the electrospun fibers of neat PVDF-HFP and various concentrations of nanoparticles were mixed with this base solution. Simple solvent mixing was employed using the acetone/DMF solvent mixture to prepare the composite solutions prior to electrospinning. The electrospinning conditions were also optimized by varying the applied voltage, tip to collector distance and speed of the rotating collector. Nice fibers were obtained at a voltage of 12-13 eV and rotating collector speed of 200 rpm. Composites of CNC with PVDF-HFP, Fe-ZnO with PVDF-HFP and the hybrid material of CNC/Fe-ZnO with PVDF-HFP were prepared and properties were investigated. All the fibers were tested for the morphology, structural, thermal and dielectric properties. The mechanical energy harvesting was performed using an assembled set up containing a frequency generator, shaker and data acquisition system. At 2 wt. % of the nanofillers, the PVDF-HFP/CNC generated about 2 V, the PVDF-HFP/Fe-ZnO generated about 4 V and the hybrid nanocomposite containing both nanoparticles generated about 6 V. The filler synergy plays a major role in regulating the material properties and here the combined effect of the piezoelectric performance of the cellulose nanocrystals and the modified ZnO nanoparticles enhanced the mechanical energy harvesting capability of the final nanocomposite. A nanogenerator is designed based on the developed polymer nanocomposite fibers and the piezoelectric performance on various conditions of stretching, pressing and twisting were also investigated. In all the cases the hybrid composite showed notable performance substantiating its application in designing self-powered nanogenerators. The dielectric properties of the hybrid material showed many fold increase in its dielectric constant, making it useful in electrical energy storage. In short, the designed device by electrospinning technique is highly useful in adding to the energy management and is environmentally safe and of good efficiency.
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Low cost anode electrocatalyst for Direct Methanol Fuel Cell applications
Authors: Syed Javaid Zaidi, Sajeda Adnan Mutlaq Alsaydeh and Ammar Bin YousafDirect methanol fuel cell has attracted worldwide attention as a promising alternative clean energy source due to growing environmental problems. A number of scientific groups are working to develop the fuel cells and make it a viable clean energy option. For fuel cells to be a feasible and economic viable innovation in the materials development, such as new electrocatalyst and polymer electrolyte membranes are required. Significant advancements in materials developments are required for fuel cells to be feasible for a wide range of portable, automotive and stationary applications. For DMFC, there are some challenges that need to be addressed before this technology become competitive, for example- slow kinetics of methanol oxidation, high methanol permeation resulting drop in fuel cell performance and the high cost of the catalyst. In the present work we focus on the electrocatalyst materials development for methanol electro-oxidation on the anode surface of DMFC. Platinum (Pt) and/or copper (Cu) based multi composition low cost electro-catalyst have been synthesized and characterized by impregnating onto the carbon nano-tubes (CNT) composites. These nanocomposite electrocatalyst materials have been characterized for their morphology by scanning electron microscopy (SEM), structure by X-Ray Diffraction (XRD), element mapping and other chemical and thermal properties by Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray Photoelectron Spectroscopy (XPS). The results of the characterization confirmed successful formation of the desired electrocatalyst material. The electrochemical activity of these electro-catalysts for methanol electro-oxidation have been studied by cyclic voltametry (CV) and chronoamperometery (CA) at various concentrations of methanol and current density. The characterization and electrochemical activity tests showed good performance for the electro-oxidation of methanol for DMFCs. The present study opened up new avenues for developing lower cost Pt-based catalysts with better performance. These nanomaterials have potential to be used as electrocatalyst for DMFC applications. Keywords: Electrocatalyst, nanocomposite;direct methanol fuel cells, electro-oxidation. Acknowledgements: This publication was supported by Qatar university Internal Grant No. QUUG-CAM-15\16-2. The findings achieved herein are solely the responsibility of the author[s].
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Sliding Mode Controlled drives for wide speed operation of Threephase Induction Motor
Authors: Fatima Ajaz and Rahman SyedInduction motor is widely used due to advantages in terms of performance, size, maintenance and efficiency compared to dc motor. Induction motor is either Scalar Controlled or Vector Controlled. Magnitude of voltage and frequency is controlled in scalar control and drive has better performance under steady state. The coupling effect of flux and torque makes the drive sluggish. In vector control of induction motor drive, the flux and torque producing currents are independent of each other, making the transient response of the system better. Direct and indirect vector control is classified depending upon how the magnitude and position of the flux vector are determined. The specifications or parameters of the induction motor have least effect on the performance of the induction motor drive. This is because the measured or estimated flux is processed in the feedback loop for speed control operation of the drive. However, use of flux sensor within the machine which makes the drive uneconomical. In indirect vector control, rotor position signals are used for instantaneous rotor flux magnitude and position estimation. Motor parameters, used for estimation of flux vector vary with frequency, magnetic saturation and temperature. Vector Control is achieved using any of the rotating flux vectors in the induction motor. The vector control must have independent control of flux and torque, rotor flux orientation provides the independent control or natural decoupling. This decoupling leads to improved stability and enhanced dynamic response. Sensitivity is the problem associated with terminal quantities based flux observers. Research has been carried out to overcome the aforementioned problems by implementing accurate estimation of rotor flux. The selection criterion for the control principle depends upon the cost, accuracy, reliability and stability requirements. The uncertainties in the system parameters give way to a more robust and dynamic controller. The sliding mode control is one of the popular control techniques used to handle the uncertain system parameters, model uncertainties and external load variations which exist in induction motor drives. The induction motors used in traction require low speeds only during starting and low speed operations. The power output of the motor can be maximized by limiting the current drawn by the motor to rated value and lowering the reference voltage. The sliding mode control offers a robust tracking of a given speed demand when subjected to disturbances from both input and output side. This gives better performance compared to other techniques. Control Algorithm: Sliding Mode Controlled three-phase induction motor is shown in Fig. 1. It consists of three-phase rectifier converting the ac grid voltage into dc voltage which forms dc bus for PWM Inverter. Sliding mode algorithm is used for controlling the inverter which powers the three-phase induction motor.The aim of the control algorithm is to control the inverter voltage so that the induction motor tracks the desired speed. Two-line voltages and phase currents are sensed into the controller. These line quantities are converted to α-β components by the conventional 3-phase to 2-phase transformation. Synchronous speed is determined using frequency estimator and then estimated mechanical speed is compared with speed reference to give speed error. This error forms the input for the Sliding Mode control. In addition to this, torque current reference and actual torque current component are compared to give the voltage reference Vds. The voltages are converted to Va, Vb and Vc using the reverse transformation. By conventional Sine-triangle comparison, switching pulses are generated. SIMULATION RESULTS: Motor response with Indirect Field Oriented Control is as shown in Fig. 2. It can be observed that the motor accelerates at the starting with maximum torque. As the motor reaches the desired speed, the generated torque becomes minimum. At t = 0.5 sec, load torque is applied on the motor resulting in the transient shown.Fig. 2 - Electromagnetic torque and Speed of the three phase induction motor with IFOC algorithm. For the same transient conditions, motor is controlled using Sliding Mode control algorithm. The results are shwon in Fig. 3. The motor torque and speed response shows lower ripple which which validates the robustness of the algorithm.Fig. 3 - Electromagnetic torque and speed of the three phase induction motor with Sliding Mode Control.
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Rheological studies of a water based drilling mud suspended with carbon nano particles
Authors: Anoop Kanjirakat, Reza Sadr, Rommel Yarc and Mahmood AmaniThe constant increase in energy demand necessitates exploration of new oil fields at challenging reservoir environments. A proper selection of the drilling fluid, or a drilling mud, is crucial in minimizing the cost and time required for the drilling process. The circulating drilling fluid aids in cooling, lubricating the drilling bit and in removing the rock cuttings from the drilling well. Water-based muds are widely used as a drilling fluid in oil and gas industry while exploring the hydrocarbon. During deep-sea drilling activities at extreme depths, high-temperature and high-pressure (HTHP) conditions are encountered. These results in overheating of drilling equipment and malfunction due to lost circulation posing a severe limitation to the drilling fluid used. Several studies have been conducted to enhance the rheological and thermal properties of water-based drilling muds. Owing to the enhanced thermo-physical properties and stable nature, suspensions of nanoparticles have been suggested to be used along with drilling fluids for such conditions. Colloidal suspensions containing nano-sized particles (1-100nm) in a basefluid are generally termed nanofluids. Rheological characteristics of various nanofluids prepared from different types of nanoparticles have been thoroughly studied in the past. However, the effect of nanoparticles on drilling fluids at high temperature and pressure conditions are not investigated in detail. In the present work, the rheological study of nanomud suspensions prepared by adding multi-walled carbon nanotubes (MWCNT) into the drilling fluid is conducted. A Nanofluid suspension based on CNT is deemed advantageous due to its high thermal conductivity, and efficient mechanical properties. High-pressure and high-temperature rheology of a nanomud suspension is reported here. The CNT-drilling mud nanofluids (nanomuds) are prepared using a top-down approach. Initially, the water-based drilling mud (base fluid/basemud) is prepared. The Water Based Mud (WBM) used in this study contain Bentonite (1%) and Barite (7%) which makes up the total percentage of solids by volume of the whole mud with a 12.5 ppg (pounds per gallon) as the final weight. The Bentonite was initially mixed with the water and seated for approximately 16 hours of hydration to form Prehydrated Bentonite or PHB. A high-pressure high-temperature (HPHT) viscometer (Chandler Viscometer 7600) is used for the rheological analysis. The viscometer is designed for rheological studies of drilling fluids while subjected to varying drilling well conditions in accordance with ISO 10414-1, 10414-2 and API 13 recommended practices. As the variation of the pressure and temperature would influence the measured viscosity values of the suspension, two independent experimental schedules are performed. Automated measurements are recorded once the pressure and temperature values of the sample have reached the set values. Viscosity values are measured at a maximum pressure of 170 MPa with temperatures ranging from ambient to 180°C. The effect of MWCNT nanoparticle concentration and variation in shear rate are also investigated. A shear thinning non-Newtonian behavior is observed for the basemud and the nanomud samples at all pressures and temperatures. The basemud showed an increase in viscosity with an increase in pressure. However, with MWCNT particle addition, this trend is observed to have reversed.
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A New Converter Topology to Increase Energy Harvesting of Large Scale PV Power Plants
Authors: Sinan A Sabeeh Al-Obaidi and Dr. Prasad EnjetiA new voltage and current balancing topology is introduced to enable a better energy yield from central inverters for large-scale solar power plants. The proposed balancing topology is characterized by its fractional power rating, high efficiency, scalability and low cost. The approach uniquely locates the maximum power point (MPP) for the system using a new developed algorithm such that it will increase the overall system efficiency. The proposed approach would be using a two staged differential power converter where the PV voltage and current are measured during each period of operation and the power converter will keep adjusting itself to maintain operation at the maximum power point. The two stages differential power converter is not a substitute for the central inverter; a central inverter would still be required to achieve maximum power point by matching the maximum available current and voltage seen by the inverter. The proposed two stages differential power converter is a new concept which addresses various needs of the present and future power generation units in the grid. The main advantages for the multistage differential power converter are: 1- The MPP is efficiently distributed on system level and each stage will match both voltage and current to reduce circulating power and maximize harvested power. 2- The controls are less complex than other existing solutions. 3- Less number of blocks, passive components, and switches used to run the new system for full integration with the grid. 4- Commercially practical solution since it requires simple control techniques and optimizes overall system efficiency. The first stage of the power differential converter is called the power sharing converter (PSC), and the second stage is voltage balancing converter (VBC). The PSC is a half H-Bridge circuit that has two PV groups are connected to it as an input to the converter; the PSC will adjust the total current between the two PV groups such that the current difference will be created between them equal to the maximum current available by one group subtracted from the other PV group by using passive element such as inductor between the two groups. VBC is also in the form of half H-bridges connected in parallel. Therefore, it would see all the available voltages by the connected strings such that each of the VBC would balance the voltages between the different strings. The voltage balancing is done by adjusting the switching duty ratio of the half H-Bridge switches. The proposed design gave an extra degree of freedom in creating better power matching conditions within each PV group as well as on the system level. The modeling equations for the proposed system was derived and proved the robustness of the proposed system. The simulation results showed the effectiveness of the proposed circuitry along with the newly proposed MPPT design, and it showed the system energy harvesting efficiency was 98% in comparison to the traditional method with 63% efficiency designed for a PV power plant with capacity of 160 KW. The circuit would be implemented in hardware design using Gallium Nitride (GaN) switches with switching frequency of 100 KHz which can endure high voltage rating and moderate current levels.
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Modeling Residential Adoption of Solar Energy in the Arabian Gulf Region
Authors: Antonio Sanfilippo, Nassma Mohandes and Marwa Al FakhriModeling the diffusion of residential solar photovoltaic (PV) systems in their social, political and economic context is crucial to help policymakers assess which policies may best support adoption. Current models of renewable energy adoption [1, 2, 3, 4] assume regulatory and incentive frameworks that do not apply to Gulf Cooperation Council (GCC) states, where energy tariffs are strongly subsidized, tax credits are not viable due to the lack of personal income tax, and support for distributed generation through grid access policies such as the Feed-in Tariff and Net Metering is not available. The goal of this study is to address this gap by analyzing the impact of home ownership, the falling cost of PV, the reduction of electricity subsidies, the introduction of a carbon tax, and the diffusion of innovation on the residential adoption of solar PV technologies in Qatar. Our objective is to develop a social simulation platform that helps policymakers and other stakeholders assess the optimal regulatory framework to promote the adoption of building-integrated PV systems in Qatar and other countries which share a similar geographical, political, economic and social context. We present an agent-based model for residential adoption of solar photovoltaic (PV) systems in the state of Qatar as a case study for the Arabian Gulf Region. Agents in the model are defined as households. Each household corresponds to a dwelling in the Al Rayyan municipality of Qatar that is either owned (by citizens) or rented (by expatriates). The objective of the model is to evaluate PV adoption in terms of these two household cohorts under diverse regulatory and incentive scenarios. In the present state of affairs, only Qatari citizens can own property in Al Rayyan and Qatari households are exempt from electricity charges. Therefore, home owners are Qataris who have free electricity, while renters tend to be expatriates who pay for electricity. The more competitive the cost of electricity from residential PV systems is as compared to the electricity tariff, the more likely are household agents to adopt solar PV. Several factors can contribute to make the cost of electricity from residential PV more competitive, including: the falling cost of PV due to increasing technology maturity the reduction of subsidies for electricity and the gas used for electricity production the introduction of a carbon tax the extension of the electricity tariff to Qatari households the neighborhood effect, which implements peer effects on the diffusion of PV innovation as a percent discount on residential PV cost. We compute solar PV adoption as resource limited exponential growth. Households adopt solar PV with a probability established by the logistic function in (1), where L is a scaling constant, e is the natural logarithm, x is the cost of electricity from residential PV systems and k is a parameter which determines the slope of the adoption curve. We set L = 1 to normalize the output of the logistic function as a probability. For the k parameter, we select a value (k = 0.59) that in the null-hypothesis scenario yields a PV market share that is equivalent to the innovator cohort of adopters in Rogers' adoption/innovation curve (2.5%) [5]. According to Rogers, “innovators are active information seekers about new ideas”, who are close to the scientific community and other innovators, have financial liquidity, and are willing to take high risks to pursue their vision. The rationale for restricting adopters to innovators in the null hypothesis scenario is that only eco-warriors with financial means and high technology awareness would adopt in the absence of incentives, with high PV costs.(1) f (x) = L / 1 + e^(-k*x) At each simulation tick, each household agent that has not adopted yet, is presented with the opportunity of doing so. Adoption is determined randomly according to the output of the logistic function in (2): a random probability p is generated, and if the probability of adoption as calculated by (1) is greater or equal to p, adoption occurs. We analyze three alternative simulation scenarios: Scenario 1 – Business as usual: no measures are introduced to incentivize PV, the neighborhood effect is active, and the price of PV falls due to increasing technology maturity Scenario 2 – 40% of gas and electricity subsidies are curtailed, the neighborhood effect is active, a carbon tax of $8/tCO2e is introduced, the price of PV falls due to increasing technology maturity, and citizens continue to have free electricity Scenario 3 – same as scenario 2, with the variant that citizens to pay for electricity. As baseline, we establish a null hypothesis scenario, which is the same as scenario 1, except that the price of PV does not fall due to increasing technology maturity. Details of the simulation results are provided in the attached file to this submission. Our study suggests that Qatar's residential PV adoption is strongly promoted by the falling cost of PV and can be further facilitated through the reduction of electricity subsidies and the extension of the electricity tariff to Qatari households, which are currently exempt. The introduction of a carbon tax can also play a role in accelerating residential PV adoption, if above $8 per metric ton of carbon dioxide equivalent. The ensuing PV adoption rates would help facilitate the national targets of 2% electricity production from solar energy by 2020 and 20% by 2030.
References
[1] Zhao, J., E. Mazhari, N. Celik, Y.-J. Son. “Hybrid agent-based simulation for policy evaluation of solar power generation systems”. Simulation Modeling Practice and Theory 19, (2011): 2189‒2205.
[2] Paidipati, J., L. Frantzis, H. Sawyer, A. Kurrasch. “Rooftop photovoltaics market penetration scenarios”. Navigant Consulting, Inc., for NREL: February, (2008).
[3] Drury, E., P. Denholm, R. Margolis. “Modeling the US rooftop photo- voltaics market”. In National Solar Conference 2010, 17‒22 May 2010, Phoenix, USA, (2010).
[4] Graziano, M. and K. Gillingham. “Spatial patterns of solar photovoltaic system adoption: the influence of neighbors and the built environment”. Journal of Economic Geography 15, (2015): 815‒839.
[5] Rogers, E. M. Diffusion of innovations. New York, Free Press of Glencoe, RS(N), (2010).
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Protecting environment and assuring efficient energy transfer using ionic liquids
Authors: M Fahed Aziz Qureshi, Tausif Altamash and Majeda KhraishehGas hydrates are ice-like crystalline compounds that are formed when small gas molecules get trapped within the water molecules under high pressure and low-temperature conditions in oil and gas transmission lines. The formation of these hydrates is a major threat to oil and gas industry as they have a tendency to agglomerate and completely block the oil and gas transmission lines, which may lead to an explosion or cause unwanted operations shut down. Therefore, annually industry spends around 1 billion US dollars on hydrate prevention procedures which includes extensive use of chemical inhibitors. These chemical inhibitors are generally classified as thermodynamic hydrate inhibitors (THI) and kinetic hydrate inhibitors (KHI). The thermodynamic hydrate inhibitors function by shifting hydrate dissociation temperature to lower values and kinetic hydrate inhibitors function by delaying the hydrate formation time. The commercial THI like Methanol and Mono-ethylene glycol (MEG) perform well, but these inhibitors are required in large quantities (> 30 wt%) and cannot be easily disposed of into the environment. Therefore, there is a strong industrial need to design inhibitors that are environmentally friendly and are required in low dosage. Ionic liquids (ILs) well known as ionic fluids are a type of organic salts that have low melting points and tendency to stay in a liquid form at low or ambient temperature. Ionic liquids are extensively being used in different chemical processes due to their negligible vapor pressure and low viscosity. Recently, ionic liquid has been recognized as the dual functional inhibitors as they have the tendency to perform as kinetic hydrate inhibitor and thermodynamic hydrate inhibitor simultaneously. In this experimental-based work, the thermodynamic inhibition (TI) and kinetic inhibition (KI) effect of ionic liquids (ILs) 1-Methyl-1-Propyl-pyrrolidinium Chloride [PM-Py][Cl] and 1-Methyl-1-Propyl-pyrrolidinium Triflate [PM-Py][Triflate] have been investigated on a methane-rich gas mixture at different concentrations (1–5 wt%) and pressure ranges (40–120 bars). The effect of the addition of synergists with ionic liquids has been also studied and the experimental results have been compared with the commercial thermodynamic inhibitor methanol and literature data. All the experimental work has been conducted using PSL system tecknik rocking cell assembly (RC-5). The ionic liquid [PMPy][Cl] was found to be more effective than the IL [PMPy][Triflate].These experimental results, clearly show that the selected ionic liquids have a tendency to act as thermodynamic and kinetic inhibitors both simultaneously. In order to improve the kinetic inhibition effectiveness of the ionic liquids, the synergist polyethylene oxide (PEO) was added in equal ratio with the ionic liquids [PMPy][Triflate] and [PMPy][Cl]. The addition of PEO helped to enhance the kinetic inhibition effectiveness of these inhibitors significantly and delayed the hydrate induction time by 6 to 14 hours at the pressure range of 40–120 bars. A delay of 6 to 14 hours in hydrate induction time is highly beneficial for process operators as it allows them to take necessary action to avoid process disruptions as a result of hydrate formation. Acknowledgement This work was made possible by NPRP grant # 6-330-2-140 and GSRA # 2-1-0603-14012 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.
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Conjugated polymer's side chains postprocessing for improved molecular packing and mobility of organic thinfilm transistors OTFTs
More LessSoluble conjugated polymers have nowadays attracted broad academic and industrial spotlight as innovative materials of easy tuneable optical and electronic properties.1 These properties translate into various optoelectronic applications such as organic solar cells, light-emitting diodes (LEDs), and thin film transistors. The pivotal parameters that define characteristics of conjugated polymer based devices are of chemical (structure, solubility, mass) and mechanical (macroscopic) nature.2 Although the physical properties CPs is determined by designed chemical structure, critical alterations result from variations of the nanostructure of the polymer in its solid state.3 Therefore the complete optoelectronic potential of CP based device can be fully assessed only with the optimal conjugated chains alignment. We envisioned thermal and UV induced post processing of conjugated polymers predesigned to dramatically change their properties in given conditions by removal of nonconductive side chains and reducing interlayer distance.
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Estimation of Groundwater Recharge in Arid Regions Using GIS: A Case Study from Qatar
Authors: Husam Baalousha, Nicolas Barth, Fanilo Ramasomanana and Said AhziAquifers are important sources of water in arid areas, where no surface water exist. Estimation of groundwater recharge from rainfall is a big challenge for hydrogeologists, due to the high uncertainty involved. It is even harder to estimate recharge in arid areas, due to high variability of meteorological parameters in space and time. Unlike recharge in humid and sub-humid areas, recharge in arid areas occurs indirectly after rainfall-runoff accumulates in low lands such as land depressions and recharges the aquifer. A new method for recharge estimation in arid areas has proposed in this study based on soil-water budget model and utilizing geoprocessing tools in GIS. The method uses Digital Elevation Model (DEM), land-cover and rainfall distribution to estimate runoff accumulation in depressions. The soil-water budget model is then applied to estimate the groundwater recharge in areas of runoff accumulation. The geoprocessing tools in GIS such as flow direction and flow accumulation in Spatial Analyst were utilised. The application of the proposed methodology in GIS makes it easy to cover the entire area of study, and to run maps algebra. The method was applied to the entire area of Qatar. The proposed methodology was applied on Qatar as a case study. The spatial resolution of raster maps was 350 by 350 m and the temporal resolution is one day. Data requirements for this study include daily records of rainfall, Digital Elevation Model (DEM) for topography, soil-moisture holding capacity, land-use map and potential evapotranspiration. Recharge is calculated for each cell and summed to provide the total amount. The proposed methodology was applied on the entire country of Qatar using the hydrological year 2013-2014 and daily time steps. This year was selected because enough daily rainfall data was available for this period, with a good coverage of the entire country. Results obtained in this study for the hydrological year 2013/2014 show the total groundwater recharge is approximately 14 million m3, and concentrated more in the northern part of Qatar. The method can be applied on any arid region.
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Vertical zonation and functional diversity of fish assemblages revealed by ROV videos at oil platforms in The Gulf
About one third of the oil and gas extracted worldwide comes from offshore sources. There is currently thousands of large-scale oil and gas platforms spread across the seas and coastal oceans, from the North Sea to the seas of South Asia. Although their primary purpose is not related to enrichment of biodiversity, gas and oil platforms can act as large and complex artificial marine habitats for a wide range of marine organisms, including sessile invertebrates and fishes. These structures have shown to enhance ecosystem function, especially secondary fish production, relative to adjacent natural reefs, besides being among the most productive marine fish habitats globally. Indeed oil platforms constitute important fish aggregating devices, especially in areas subjected to a range of environmental perturbations. Hard substratum availability combined with exclusion zones around these structures allows for the development of diverse fish assemblages. We carried out the first assessment of vertical distribution, diel migration, taxonomic and functional diversity of fishes at offshore platforms in the Arabian Gulf. Video footages were recorded at the Al Shaheen Oil Field, between 2007 and 2014 using a Remotely Operated Vehicle (ROV). Indeed diving and snorkeling are strictly forbidden in the exclusion zone around offshore platforms, precluding conventional monitoring techniques such as underwater visual census, collection of sessile organisms, etc. Routine inspection and maintenance surveys, however, are conducted to monitor the state of underwater structures using ROVs. A total of 4,510 video files, containing 120 hours of underwater video recordings, were provided by Maersk Oil Qatar A/S. These videos were recorded over six years (2007, 2009, 2010, 2011, 2012 and 2014), during day and night, at the 9 platform locations (A-I) within the Al Shaheen Oil Field using a ROV of the model SAAB Seaeye Surveyor Plus 229. To assess the local fish community, a total of 242 videos amounting to twenty-one hours of observation were selected randomly, however, if no fish appear in a selected video a new video was randomly selected from the list. This work represents the first assessment of reef fish communities inhabiting oil and gas platforms in the Arabian Gulf. A total of 12,822 fish, belonging to 83 taxonomic groups were recorded around the platforms. Among them, two species are first recorded for Qatari waters: Cyclichthys orbicularis and Lutjanus indicus. In addition two chondrichthyes, one endangered (Stegostoma fasciatum) and a vulnerable species (Taeniurops meyeni), were also observed across the platforms. Several trends were found in the vertical distribution of the fish community, most species were observed between 20 and 50 m depth and higher fish abundance recorded in the upper layers, down to 40 m depth and decreasing with depth. Vertical variation, however, in fish diversity was generally not accompanied by differences in vertical movements. The vertical variation, however, in fish diversity was not accompanied by differences in vertical movements of the fish. These results suggest that the vertical zonation pattern does not change, or only changes slightly, on a daily basis. The mean centers of mass of the most abundant fish species did not overlap, likely due to potential competition or niche differences. The dominant trophic groups were carnivores and invertivores, being well represented at each depth range (each spanning 10 m) from surface to seabed. Diel vertical movement was observed only for Acanthopagrus bifasciatus, which was concentrated at shallow depths during the daytime but migrated to deeper layers at night. The functional indices showed no significant differences between water depths or diel cycles (day / night). Besides the temperature variation, the reduced light penetration due to platform structures makes difficult the algal growth necessary for browsing herbivorous fish. Thereby, the effect of sunlight penetration may be reflected in the vertical distribution of herbivorous fish, which are rare in deeper layers. Planktivores are densely grouped within and just below the thermocline, which is located around 18 m during summertime. The study demonstrates that oil platforms represent a hotspot of fish diversity and interesting sites for studying fish communities, abundance and behaviour.
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Adaptive model of thermal comfort for office buildings in GCC
Authors: Roberto Indraganti and Djamel BoussaaThe Gulf Cooperation Council (GCC) nations top the world in CO2 emissions/ capita. However, plummeting oil prices and increasing energy demands necessitate rethinking on thermal comfort delivery. This region has warm desert climate throughout. In GCC states, the adaptive comfort standard or the precursor field studies to develop one are non-existent. We carried out thermal comfort field studies in Qatar for thirteen months. In ten typical air-conditioned office buildings, 1175 voluntary subjects completed 3742 questionnaires, while their thermal environments were simultaneously measured. This paper proposes the adaptive model of thermal comfort for GCC. Adopting variable indoor comfort standards that track the outdoor conditions may be effectual in meeting the sustainability goals of the GCC and Qatar Vision 2030.
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Designing Photo Absorbing Materials by Cation Substitutions for Photovoltaics
More LessDesigning Photo Absorbing Materials by Cation Substitutions for Photovoltaics Merid Legesse1, Heesoo Park1, Fedwa El Mellouhi1, Sergey N Rashkeev1, Sabre Kais1, 2, 3, Fahhad H Alharbi1, 3 1Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Doha, Qatar. 2Department of Chemistry and Physics, Purdue University, West Lafayette, Indiana 46323, USA. 3College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar. Email: [email protected]. Recently, significant research efforts have focused on some emerging solar cell technologies such as dye-sensitized solar cells, perovskite photovoltaics, etc. However, these technologies face many challenges. In this talk, we will present a new family of light absorbing materials so-called pyroxene silicates. These materials are abundantly present in the earth crust however, bandgaps of naturally formed pyroxene silicates such as NaAlSi2O6 are quite high (∼5 eV). Therefore, it is important to find a way to reduce bandgaps below 3 eV to make them usable for optoelectronic applications [1, 2, 3]. Using first-principles calculations we investigated the possibility of band structure engineering of pyroxene silicates with chemical formula A+1B+3Si2O6 by proper cation substitution (A+ = Na, NH4+, PH4+, SH3+, CH3NH3+, CH3PH3+, CH3SH2+ and B3+ = Al3+ Ga3+, In3+, Tl3+). We found that appropriate substitutions of both A+ and B3+ cations can reduce the bandgaps of these materials to as low as 1.31 eV. In this talk, we will also discuss in details how the bandgap in this class of materials is affected and thermodynamic stabilities. We would like to thank Qatar National Research Foundation (QNRF) for the support (Grant No. NPRP 7-317-1-055. References (1) A.A.B. Baloch, S.P. Aly, M.I. Hossain, F. El-Mellouhi, N. Tabet, and F.H. Alharbi, Sci. Rep. 7, 11984 (2017). (2) F. El Mellouhi, A. Akande, C. Motta, S.N. Rashkeev, G. Berdiyorov, M.E.A. Madjet, A. Marzouk, E.T. Bentria, S. Sanvito, S. Kais, and F.H. Alharbi, ChemSusChem 10 1931 (2017). (3) F.H. Alharbi, S.N. Rashkeev, F. El-Mellouhi, H. P. Lüthi, N. Tabet, S. Kais, npj Comput. Mater 1, 15003 (2015).
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Core Scale Analysis on Asphaltene Flocculation Inhibition and Deposits Removal by Ultrasonication
More LessAsphaltene buildup in the near wellbore region is an increasingly problematic phenomenon, especially in mature fields. Research on ultrasonic treatment to address this issue has increased in recent years, with a field trial on mature fields exhibiting favorable characteristics. Investigation of petrophysical characteristics, precipitation of asphaltenes in rock samples, employment of ultrasonication to remove/inhibit deposits, investigation of optimum sonication time, and the resultant increase of permeability to brine and crude oil are discussed and illustrated. Prevention and or removal of asphaltene deposits inside the wellbore as well as the nearby wellbore region can significantly improve in the recovery of the petroleum reservoirs.
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An Investigation of the Factors Affecting Barite Sagging Related to Drilling Fluid Properties
More LessDrilling phase is one of the most important parts of developing a field. The durability of the well and its performance is greatly related to the quality of the drilling. A good drilling will also have an effect on how fast the project can start make profits as the drilling phase become shorter and more efficient. There are number of different factors that can hinder the quality of the drilling job and in some cases stop it or damage the wellbore and cause catastrophic disasters. Barite sagging is a one of the main causes of damage in the wellbore during the drilling stage. Any drilling job needs a drilling fluid that can provide the engineers with: enough hydrostatic pressure to prevent the well from collapsing in, removing the drilling cuts to the surface, cools down and lubricates the drill bit during the drilling job, suspend the drilling cuts within itself during the drilling and when drilling is stopped,seal the permeable zones in the wellbore to prevent lost circulation, control the corrosion caused by corrosive gasses such as H2S, provide hydraulic energy to the bit to fasten and improve the drilling and finally help the engineer to the cementing and completion after the drilling was done. Barite Sag is a common phenomenon that occurs while drilling for oil and gas. Barite, BaSO4 is a weighing agent used to increase the density of drilling fluids to a desired level. It has a high density of 4.2 g/cm3. The problem that occurs in this phenomenon is that as the mud is circulated through the borehole, the barite that was dissolved in the mud starts separating from the liquid phase and settles down. This separation of barite from the aqueous phase creates an undesired density gradient and causes a lot of further problems. Barite sag can occur in both conventional and deviated wells. In vertical wells, higher density drilling fluids or barite-rich phase settles on the bottom of the well bore while the lower density fluid form layers on the upper part of the column. This usually occurs during static conditions i.e. when drilling is stopped or very low shear rate (rpm). Additionally, a very low shear-rate viscosity can also result in barite sag. However, deviated wells are more susceptible to barite sag as in deviated wells, gravity induces an additional settling effect which results in sediment beds of barite at the bottom of the borehole. In deviated wells, Boycott effect is the reason for barite sagging. In an inclined tubing, the vertical distance of the settling particles is greatly reduced as compared to that in vertical columns. Hence the process of sedimentation is accelerated. Barite sagging can cause some serious problems during drilling operations. These problems are: loss of mud circulation, well bore instability, and uneven mechanical friction which can cause pipes and tools to get stuck downhole. Barite sagging, if not controlled properly, can lead to a complete shutdown and well abandonment. Hence, this study is being conducted to look in detail at the various chemical and physical factors, that affect barite sag, so that more viable and optimal solutions can be derived to control the extent of barite sag. Barite sagging is just a general term used to describe the phenomenon of which the weighting material detaches itself from its own liquid phase and slowly settles down the wellbore. But many more specific examples of barite sagging have been looked into and researched to further expand our understanding of this phenomenon. From dynamic to static sagging, in wells that are vertical, horizontal or deviated, all of these scenarios have been heavily examined and studied. The extent of the research that has been done in regards to barite sagging is surely well deserved as barite sagging can cause major problems while drilling in the field such as loss circulation, sudden changes of density in the drilling fluid which could further escalate into a blowout. Problems with cementation, well control issues and stuck pipe, all have been encountered mainly due to barite sagging. The research papers available look into a wide range of aspects related to barite sagging, but I will mainly look at the research conducted that studies adding different substances into the drilling fluids and comparing the effects that the new substances can cause to the sagging affect. Another major topic that I will try to cover is the different methods that have been used through the years to measure barite sagging in the laboratory environments.
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A Pilot Study on Evaluating the Microbial Quality of Produce Sold at the Wholesale Produce Market in Doha Qatar
Authors: Israa El-Nemr, Mohanad Mushtaha and Ipek GoktepeEnvironmental and sanitary conditions play a major role on the quality of fresh produce. The Wholesale Produce Market (WPM) in Doha is an open-air market located in close proximity to the livestock market and slaughterhouse. Currently, there is no data available on establishing the link between the microbial quality of produce sold at this market and environmental factors affecting the quality of produce. Therefore, this pilot study was carried out to evaluate the effect of environmental conditions (e.g.; seasonal temperature, humidity, hygiene conditions of the market) on the microbial quality of produce sold at the WPM. Triplicate samples of different produce samples (e.g.; tomato, lettuce, parsley, cucumber, and green onion) were collected monthly starting from July 2016 to June 2017. Selective media were used to determine the target microorganisms (e.g.; total aerobic bacteria-PCA, total E.coli - MCA, total Listeria – LSA, total coliform - EMB, total Staphylococcus - BPA, total Salmonella - XLT4, and total fungal growth – PDA). The colonies identified as presumptive target organisms were isolated and identified using molecular techniques. The results indicated that produce samples (especially parsley, green onion, and lettuce) tested in this study were highly contaminated with various microorganisms based on the PCA, MCA, and EMB counts. The microbial analysis of produce samples revealed that the most dominant strains in summer months (47°C daytime and 25°C nighttime) were Bacillus, Enterococcus, and Klebsiella. While, Pseudomonas and Enterobacter were the most abundant species during the winter months (24°C daytime, 12°C nighttime). In addition, Penicillium, Aspergillus, and Fusarium were the most commonly isolated fungal species during the months of November-January. It is clear that environmental conditions, such as temperature and humidity are the major factors affecting the growth of different microorganisms in fresh produce. Although no pathogenic target bacteria were detected in the produce samples at WPM, the relatively high PCA and EMB counts demonstrate the need to improve the sanitary conditions at this major produce market in Qatar.
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Photodriven Molecular Systems for CO2 Reduction
More LessAlessandro Sinopoli, a Michael Wasielewski, b Muhammad Sohail. a aQatar Environment & Energy Research Institute, Hamad Bin Khalifa University, PO Box 5825, Doha, Qatar; bDepartment of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA. The use of fossil fuels, especially natural gas, which has a lower carbon burden than oil or coal, will continue to dominate the energy market for the next several decades. In order to mitigate the large amounts of CO2 released into the atmosphere, it is essential to have clean ways of converting the CO2 back into a high energy density liquid fuel. Benchmark catalysts for CO2 reduction typically employ second and third row transition metals like palladium, iridium, and rhenium. The rarity, cost, and environmental ramifications of mining large quantities of such precious metals deter scaling up the usage of such catalysts. Developing a CO2 catalytic system that uses earth abundant first row transition metals like manganese, will push the field away from rare earth metal catalysts. While still an emerging field, transition metal-based catalysts can be successfully integrated in electrochemical and photoelectrochemical devices for CO2 reduction. Inside this class of compounds, developing manganese-based systems remains an extremely promising strategy for the advent of low cost but at the same time efficient molecular systems for CO2 reduction. We will therefore investigate Mn(bpy)(CO)3Br and its related derivatives that have recently been shown to efficiently reduce CO2 to CO. More importantly, none of these Mn-bipyridine complexes have yet been integrated with a covalent photo-driven source of electrons and this will be the main synthetic and experimental challenge within this project. Aromatic organic anions (radical anions or closed shell dianions) are reactive species involved in various chemical transformations. The photochemistry and photophysics of these species have been the subject of extensive study since they have been implicated in many photo-induced electron transfer processes, and are suggested to be powerful reducing agents. Such properties were substantiated by the observation of rapid electron ejection to give solvated electrons, electron-cation pairs, or reduced electron acceptors upon photolysis of aromatic anions (e.g. sodium pyrenide or biphenylide). We envision that the high reducing power (up to − 3 V vs. SCE) of excited monoanions or dianions of aromatic diimides can be exploited for CO2 reduction catalysis. In particular, the anions of PDI perylene-3,4:9,10-bis(dicarboximide) and its homolog naphthalene-1,8:4,5-bis(dicarboximide) (NDI) will be used as the primary photosensitizers in this study. These planar, chemically robust, redox-active compounds are widely used as industrial pigments, supramolecular building blocks, photooxidants, and n-type semiconducting materials. In the effort of integrating NDI and PDI units in the design and development of manganese based photocatalysts, experiments will be carried out in two stages. In the first stage, we will synthesise photosensitizer systems designed specifically to act as catalysts, so that their structures and properties can be determined. Figure 1. Examples of Mn-based catalysts designed for this project. The structures depicted in Figure 1 are examples of PDI and NDI photosensitizer systems designed for this project. For example, in the molecule on the left (Figure 1), two easily reducible PDI molecules are covalently attached to the bpy ligand. One-electron reduction of PDI will produce the stable PDI-• radical anion. The structure of the designed manganese complexes, the dynamics of CO2 binding, and subsequent protonation of the bound Mn carboxylate will be studied using femtosecond transient absorption spectroscopies with both UV-Vis and mid-IR probing as well as and femtosecond stimulated Raman spectroscopy (FSRS). The second stage of the experiments will study the laser-generated Mn(0)(bpy)-1(CO)3-based catalyst followed by CO2 binding and protonation. For this we will perform steady-state photolysis experiments on the systems in DMF with varying amounts of HBF4 and CO2 up to the limit of a saturated solution of CO2 in DMF at 25 °C and 1 atm, which is about 0.14 M. These studies will look for products generated following one-electron reduction of the Mn catalysts. We will quantitate the yield of CO produced by the overall photoreaction using a 16-sample parallel system in which the samples are illuminated using filtered LEDs and a parallel, continuous gas sampling system connected to a gas chromatograph. The system will be calibrated with appropriate standard gas mixtures, and a full range of conditions and appropriate control experiments will be performed by varying the concentrations of catalyst, CO2, HBF4, and sodium ascorbate in the solution. Solar energy, an abundant resource in Qatar, can drive CO2 reduction to produce both liquid solar fuels and potentially high value chemicals. In this regard, our study will represent the birth of a new generation of efficient photocatalytic systems for CO2 reduction by coupling robust light harvesting molecules with earth abundant transition metals like manganese.
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Corrosion behavior of high strength low alloy HSLA steel in 35 wt% NaCl solution containing diethylenetriamine DETA as corrosion inhibitor
High strength low alloy (HSLA) steels demonstrate improved mechanical and anticorrosion properties when compared to plain carbon steels. HSLA steels have succeeded to find their major applications in industries such as defense (gun barrel, turret), food, component manufacturing, wind tunnels, power generation, and water jet cutting, etc. There are significant economic benefits to develop novel materials to mitigate the harmful effects of corrosion. At the same time, the corrosion challenges have also been addressed using various kinds of inhibitors. The corrosion inhibitors are commonly added to the corrosive medium in order to reduce their aggressive attack on the materials to improve their inhibition performance. The smart corrosion protection leads to secure our natural resources, time, efforts, energy and will also ensure a safe operation. The aim of this research work is to study the corrosion behavior of high strength low alloy steel (APIX120) in 3.5 wt.% NaCl solution containing different concentrations of diethylenetriamine (DETA). The electrochemical behavior of HSLA steel was investigated at room temperature using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss techniques. In addition, the adsorption isotherm, activation energy and other thermodynamic parameters were calculated from the electrochemical results. The corrosion products formed on the surface of the steel were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, surface topography and surface roughness of un-corroded and rusted samples were studied by atomic force microscopy (AFM) to elucidate the effect of the aggressive media on the corrosion performance of HSLA steel. Our study discloses that the inhibition efficiency of HSLA steel increases with increasing concentration of DETA in 3.5% NaCl solution.
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Highly ordered mesoporous silica and halloysite nanotubes loaded with diethylenetriamine DETA for smart anti corrosion coatings
Authors: Abdul Shakoor, Fareeha Ubaid, Khurram Shahzad, Ramazan Kahraman, Fatima Montemor and Umair ManzoorThe development of nanoscience and technology has devoted significant attention to conducting studies on hollow particles. Among the available materials, mesoporous silica nanoparticles have recently gained attention as potential nanocontainers due to their high stability, large surface area, controllable pore diameter and easy surface functionalization as they can store and release organic or inorganic molecules of different sizes and functionalities. The aim of this work is to study the use of mesoporous silica as a potential reservoir for corrosion inhibitor for active corrosion protection of carbon steel and using epoxy encapsulated halloysite nanotubes for the self healing process of the epoxy based coatings. The synthesized mesoporous silica particles were characterized by using XRD, FTIR and SEM. Mesoporous silica particles loaded with diethylenetriamine (DETA) were embedded into the epoxy polymer along with the halloysite nanotubes (HNTs) encapsulated with epoxy monomer and amine immobilized in mesoporous silica with a weight ratio of 5 wt% of mesoporous silica. Kinetics of release of corrosion inhibitor was evaluated by electrochemical impedance (EIS) measurements in 3.5 wt% NaCl solution. The EIS analysis confirms that the release of inhibitor during the corrosion process has significantly improved the anticorrosion properties when compared to the epoxy coated sample without any corrosion inhibitor. The self healing phenomenon in the scratched epoxy coated sample was monitored by SEM during different time intervals. The SEM results showed that that the epoxy pre-polymer was slowly released into the crack.Upon release, the epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch over the sample surface. This study suggests that these novel coatings may have some potential applications in the oil and gas industry.
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Utilization of Iron Magnetic Nanoparticles for the extraction of oil from aqueous environments
Authors: Saly Matta, Manyam Praveen Kumar, Neil Adia, Sherzod Madrahimov and David BergbreiterThe goal of this research work is to help and to contribute toward the minimization and the control of manmade water pollution on land and in marine environment. Since oil spill is a major environmental polluter and causes server damage to natural habitats, the oil separation from aqueous phase using polyolefin-bound magnetic nanoparticles with superhydrophobic or water repellent properties has become a promising area of research that is worth exploring. Perfectly designed, functionalized polyisobutylene (PIB) bound iron magnetic nanoparticle could be utilized for facile separation of complex pollutants (crude oil), diesel, gasoline and organic solvents (petroleum ether, benzene, chloroform) from aqueous polluted environment conditions. 80–90% of recovery of pollutants by external magnetic field was easily reached and resuse of polyisobutylene-catechol bound to magnetic nanoparticle was investigated in detail. Polyisobutylene-catechol grafting on iron magnetic nanoparticle obtained 42–52%. Stability of the terminally functionalized polyisobutylene-catechol bound to iron oxide was confirmed by UV-Visible spectroscopy studies. Moreover, these experiments suggest that this work might provide promising candidate for environmental remediation including oil spill. This research work is an eco-friendly process and high oil absorption materials and can have wide applications in heterogenous and homogenous catalysis.
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Thermal Hysteresis of Palladium encaged inside Mesoporous Silica catalyst for Low Temperature CO oxidation
More LessThermal Hysteresis of Palladium encaged inside Mesoporous Silica catalyst for Low Temperature CO oxidation Rola Al Soubaihi 1,2, Joydeep Dutta2 Liberal Arts and Science Program, Virginia Commonwealth University-Qatar, Doha, Qatar Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden Carbon Monoxide (CO) is colorless, odorless gas produced from incomplete combustion of carbon fuel under conditions with a limited supply of oxygen. Catalytic oxidation is one of the effective methods of removing CO and convert it to CO2. [1] Catalyzed CO oxidation reaction finds applications in many fields such as environmental protection, air purification for buildings or cars, orbiting, closed-cycle CO2 lasers, gas masks for mining applications, CO detectors[2-3]. Depending on their size, shape, and preparation conditions, Nanocatalysts can exhibit unique properties (electrical, optical, magnetic, and catalytic) which are different from their bulk material properties [4-6]. The surface of nanomaterials contains large number of high energy defects such as surface and edge atoms that can provide active sites for catalyzing surface reactions by lowering the activation energy [7-8]. Supported Palladium catalysts are known for their high activity, recyclability, and their cheap cost when compared to platinum catalysts. Support plays a crucial role in the synthesis of such catalysts. In this regard support can reduce the amounts of the metal and ensure a good dispersion, and increase their thermal stability. Mesoporous materials with large internal surface areas (>1000 m2/g) and narrow pore size distributions can be an ideal support for Palladium based catalysts [9-10]. Silica are well known for structural and thermal properties and allow anchoring of catalytically palladium active species onto their surfaces. Silica can provide enormous beneficial features to enhance the catalytic activity such as high surface area, high porous, high thermal insulation, and local heating and heat retention [11-13]. Here, we report for the first time exceptional catalytic CO oxidation on Pd supported on mesoporous SiO2 with good stability and recycling behavior under heating and cooling conditions with wide CO Thermal hysteresis (close to 200 °C). We attribute our results to the phase transformation of Palladium to palladium oxide intermediate at different temperatures during the heating and cooling cycles and the structure and the local environment of the palladium since Pd clusters are small and highly dispersed on the silica surfaces and encaged inside the pores. References [1] S. Biswas, K. Mullick, S. Y. Chen, A. Gudz, D. M. Carr, C. Mendoza, et al., «Facile access to versatile functional groups from alcohol by single multifunctional reusable catalyst,» Applied Catalysis B-Environmental, vol. 203, pp. 607–614, Apr 2017. [2] X. Zhang, Zhenping Qu, Xinyong Li, Meng Wen, Xie Quan, Ding Ma, and Jingjing Wu., «Studies of silver species for low-temperature CO oxidation on Ag/SiO 2 catalysts.,» Separation and Purification Technology, vol. 3, pp. 395–400., 2010. [3] P. A. Wright, Srinivasan Natarajan, John M. Thomas, and Pratibha L. Gai-Boyes, «Mixed-metal amorphous and spinel phase oxidation catalysts: characterization by x-ray diffraction, x-ray absorption, electron microscopy, and catalytic studies of systems containing copper, cobalt, and manganese,» Chemistry of materials vol. 5 pp. 1053–1065., 1992. [4] A. Cubo, J. Iglesias, G. Morales, J. A. Melero, J. Moreno, and R. Sanchez-Vazquez, «Dehydration of sorbitol to isosorbide in melted phase with propyl-sulfonic functionalized SBA-15: Influence of catalyst hydrophobization,» Applied Catalysis a-General, vol. 531, pp. 151–160, Feb 2017. [5] W. Fang, Y. C. Deng, L. Tang, G. M. Zeng, Y. Y. Zhou, X. Xie, et al., «Synthesis of Pd/Au bimetallic nanoparticle-loaded ultrathin graphitic carbon nitride nanosheets for highly efficient catalytic reduction of p-nitrophenol,» Journal of Colloid and Interface Science, vol. 490, pp. 834–843, Mar 2017. [6] M. V. D. Fernandes and L. R. D. da Silva, «Structural analysis of mesoporous vermiculite modified with lanthanum,» Materials Letters, vol. 189, pp. 225–228, Feb 2017. [7] A. K. Herrmann, P. Formanek, L. Borchardt, M. Klose, L. Giebeler, J. Eckert, et al., «Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles,» Chemistry of Materials, vol. 26, pp. 1074–1083, Jan 2014. [8] R. Muller, S. H. Zhang, B. Neumann, M. Baumer, and S. Vasenkov, «Study of Carbon Dioxide Transport in a Samaria Aerogel Catalyst by High Field Diffusion NMR,» Chemie Ingenieur Technik, vol. 85, pp. 1749–1754, Nov 2013. [9] Al-Oweini, S. Aghyarian, and H. El-Rassy, «Immobilized polyoxometalates onto mesoporous organically-modified silica aerogels as selective heterogeneous catalysts of anthracene oxidation,» Journal of Sol-Gel Science and Technology, vol. 61, pp. 541–550, Mar 2012. [10] B. N. Bhadra, P. W. Seo, J. W. Jun, J. H. Jeong, T. W. Kim, C. U. Kim, et al., «Syntheses of SSZ-39 and mordenite zeolites with N,N-dialkyl-2,6-dimethyl-piperidinium hydroxide/iodides: Phase-selective syntheses with anions,» Microporous and Mesoporous Materials, vol. 235, pp. 135–142, Nov 2016. [11] S. Dilger, C. Hintze, M. Krumm, C. Lizandara-Pueyo, S. Deeb, S. Proch, et al., «Gas phase synthesis of titania with aerogel character and its application as a support in oxidation catalysis,» Journal of Materials Chemistry, vol. 20, pp. 10032–10040, 2010. [12] A. K. Herrmann, P. Formanek, L. Borchardt, M. Klose, L. Giebeler, J. Eckert, et al., «Multimetallic Aerogels by Template-Free Self-Assembly of Au, Ag, Pt, and Pd Nanoparticles,» Chemistry of Materials, vol. 26, pp. 1074–1083, Jan 2014. [13] R. Muller, S. H. Zhang, B. Neumann, M. Baumer, and S. Vasenkov, «Study of Carbon Dioxide Transport in a Samaria Aerogel Catalyst by High Field Diffusion NMR,» Chemie Ingenieur Technik, vol. 85, pp. 1749–1754, Nov 2013.
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Detection and Characterization of Karst Structures Based on Spectral Attributes of Seismic Data
Authors: Roland Gritto, Ali Elobaid Elnaiem, Valeri Korneev, Fathelrahman Mohamed and Fadhil SadooniA major hazard in Qatar is the presence of karst, which is ubiquitous throughout the country including depressions, sinkholes, and caves. Causes for the development of karst include faulting and fracturing where fluids find pathways through limestone and dissolve the host rock to form caverns. Of particular concern are the collapse of such caverns in rapidly growing metropolitan areas that expand in heretofore unexplored regions. Because Qatar has seen a recent boom in construction, including the planning and development of complete new metropolitan sub-sections, the development areas need to be investigated for the presence of karst to determine their suitability for the planned project. In this paper, we present the results of a study to demonstrate the use of seismic spectral analysis techniques to detect the presence of a karst analog in form of a vertical water-collection shaft located on the campus of Qatar University, Doha, Qatar. We also present the results of this technique to characterize the overburden over a sinkhole in the Al Duhail Area of Doha, Qatar. Seismic waves are well suited for karst detection and characterization. Voids represent high-contrast seismic objects that exhibit strong responses due to incident seismic waves. However, the complex geometry of karst, including shape and size, makes their imaging nontrivial. In our current paper we build upon previous results (Gritto et al, 2014, Gritto et al. 2016) and employ spectral techniques to demonstrate the detection and characterization of a vertical water collection shaft analyzing the spectral information of ambient seismic noise recordings that have been scattered by the object. The results indicate that ambient noise recordings may generate data with sufficient signal-to-noise ratio to successfully detect and locate subsurface voids. Being able to use ambient noise recordings would eliminate the need to employ active seismic sources that are time consuming and more expensive to operate. In the case of a vertical water-collection shaft on the campus of Qatar University, we deployed a 24 m long geophone line with 48 10 Hz three-components geophones and passively recoded ambient seismic noise data. The geophone line ran across the lid of the water-collated shaft and extended to both sides. Spectral analysis of the ambient noise data revealed an increase in low frequencies directly above the vertical shaft. The low frequencies are attributed to resonance waves that propagate circumferentially in the concrete walls of the vertical shaft. The observation of increased low-frequency energy was accompanied by a simultaneous decrease in high frequencies clearly demarking the location of the shaft. In contrast to the increase in amplitude of the low frequency resonance waves, the high frequencies of ambient noise were attenuated by the presence of the shaft. The clear demarcation of the increase and decrease in amplitudes of recorded waves by the geophones located above the shaft allows to pinpoint its location. In the second part of our paper, we analyze scattered seismic waves to characterize the overburden of a sinkhole. During this experiment at the sinkhole in the Al Duhail Area of Doha an active seismic survey was conducted. Using the same approach described above, spectral analysis of active source seismic data revealed the extent of the sinkhole, while analytical modeling of the recorded data reveals the thickness of the overburden.
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A survey on selfreported handling practices and food safety knowledge of workers at the major produce market in Qatar
Authors: Israa El-Nemr, Mohanad Mushtaha, Hammad Asim and Ipek GoktepeFood handling practices (FHP) is one of the most important stage where microbes can be introduced into produce through the infected food handlers or by cross-contamination. The fresh produce market in Doha, Qatar is the major market from which most of the food businesses, restaurants, super markets, and consumers obtain their fresh produce. Produce is handled by workers with no or minimum knowledge on safe produce handling practices. This study was carried out to assess the food safety knowledge and self-reported handling practices applied by produce handlers working at this major produce market in Qatar. About 120 produce handlers were surveyed using a systematic questionnaire (No. QU-IRB 509-E/15) to determine their food safety knowledge and attitudes during handling of fresh produce in January 2016. In addition, hand-swab samples and work uniform photos were collected. A standard microbial count were applied on the collected swabs to determine the hands' hygiene levels of the workers. The identification of microorganisms isolated from their hand swabs was carried out using MALDI-TOFF. The survey results revealed that the hygiene practices and food safety knowledge among produce handlers working at this produce market are insufficient. It was determined that none of the handlers received any food safety training on safe produce handling practices before joining the work at the market. Most of the workers' age was below 50 yrs (82.5%), about 37% of them was between 31 and 40 years old. Regarding educational level; 57.5% of them had middle school degree or below. More than 60 % of them claimed to wash their hands 4–5 times per duty time. The microbial hand-swabbing analyses demonstrated the presence of Enterococcus faecium, Klebsiella pneumoniae, Staphylococcus spp., and Bacillus circulans. Overall, these results are significant because they highlight the need to promote additional efforts that might assist in developing necessary intervention strategies to improve the conditions at this major market and prevent future foodborne illness outbreaks linked to produce sold in Qatar.
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The Influences of Produced Water Irrigation on Soil microbial succession and Turfgrass Grass Establishment in Qatar
The Influences of Produced Water Irrigation on Soil microbial succession and Turfgrass Grass Establishment in Qatar Sameera S. Shaikh, Mohammed H. Abu-Dieyeh*, Fatima A. Al Naemi, Talaat Ahmed, and Mohammad A. Alghouti Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University. *Corresponding author: [email protected] Abstract: Water scarcity around the world has necessitated the use of alternative water resources such as wastewaters, for irrigation purposes. Landscaped areas and turf grass systems provide varied environmental benefits including phytoremediation, erosion control and mitigation of heat island effects. They also provide safe, shady and cool places for athletic activities, exercise, and provide area for outdoor gatherings. Use of wastewater for turfgrasses has been conceptualized in the last decades and applied in various parts of the world. In this study, we attempted to use produced water (PW) to irrigate two turfgrass species, Cynodon dactylon and Paspalum sp., which are grown in local parks, green spaces and roadsides in Doha, Qatar. Effect of PW irrigation on established grasses, microbial succession, heavy metal accumulation and germination tests for weeds and turf grass seeds were investigated in greenhouse and field experiments. The two species of grass tested - C. dactylon and Paspalum sp. depicted different tolerance capacities towards PW. C. dactylon showed lower tolerance while Paspalum sp. depicted better tolerance capacity towards PW. C. dactylon grown from seeds under greenhouse conditions were not able to tolerate more than 30% concentration of PW. In comparison to tap water irrigated turfgrass, Paspalum sp. was found to accumulate higher concentrations of V and Pb in shoots and Cr, Ni and As in roots. For soil microbial succession studies, results from greenhouse experiment, using Cynodon dactylon turfgrass and after 14-weeks of produced water irrigation regimes, showed a significant reduction in bacterial colony forming units (CFU) at all produced water treatments compared with tap water irrigation. However, a significant increase through time in CFU occurred in all treatments. It was observed that PW irrigation caused changes in fungal species present in PW irrigated soil. The study of fungal succession in soil showed presence of certain species in 10%PW–30%PW treated soil that were absent in soil treated with tap water. Based on germination tests it was recommended that irrigation with PW be performed after turf grass establishment. Studies on weed germination suggested that PW could discourage growth of weeds - Amaranthus viridis and Launaea mucronata while promote growth of Chloris virgata. Based on the study conducted, it is suggested that PW could be used as alternative water resource to grow some species, but only after further research is conducted on the long term to assess any environmental toxicity.
Acknowledgement: This research was made possible by TOTAL, Qatar grant. The statements made herein are solely the responsibility of the authors.
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Study of polyaniline-silver nanocomposite as humidity sensor
By Jolly BhadraStudy of polyaniline-silver nanocomposite as humidity sensor J. Bhadra, A. Popelka, N. J. Al-Thani, A. Abdulkareem Center for Advanced Materials, Qatar University, Qatar Abstract In this piece of work focus on fabrication of resistive type humidity sensor using polyaniline-silver nanocomposite (PPVA-Ag). Four different nanocomposites using four concentrations of silver (0.5,1.0, 1.5 and 2.0 M) and polyaniline (PANI) dispersed in polyvinyl alcohol matrix (PVA). PANI, and PVA concentrations are kept constant. Thin PPVA-Ag film on interdigited gold electrode fingers gives excellent sensitivity towards humidity at room temperature. 1. Introduction Since last few decades the information of nanoscience and nanotechnology has been explored extensively to obtain functionalized nanomaterials. One such category of nanomaterial is the polymer- metal nanocomposite, with enhanced mechanical, elastic, optical, electrical and dielectric properties [1]. Polymer nanocomposites are materials with nanosized one dimensional inorganic filler particles (around 10–100 ˚A), dispersed in an organic polymer matrix. An important parameter which has significant importance in many industries such as food, agricultural, clinical equipment and electronics is humidity, it is considered to be one of the most frequently measured physical parameters [2-3]. With the advancement in moisture sensitive technologies, research to achieve high efficient, low cost, reliable and miniature size of material sensitive to humidity change has gained acceleration. As among metal nanoparticles, Ag has high electrical and thermal conductivities, so the composite of Ag dispersed in PANI-PVA matrix gives rise to a functional materials, with improved antimicrobial activity and sensitivity towards humidity. This paper we focus on surface analysis of the thin film obtained using scanning electron microscopy and study on the humidity sensitivity. 2. Methods 2.1 Synthesis of Ag nanoparticles Four different concentrations of silver nitrate (AgNO3) is dispersed in aqueous PVA solution under constant stirring and heating at 60°C followed by photo reduction using UV-lamp having wavelength 390 nm for 24 hours. After exposing the above solutions with UV light for 24 hours, finally, yellowish-red colloid of Ag nanoparticles with average diameters of ∼30 nm and ∼70 nm uniformly dispersed in PVA are obtained. 2.2. Synthesis of PANI-Ag nanocomposite and pure PANI: The PANI-Ag nanocomposite blend is synthesized by in-situ chemical polymerization (Figure-1) of aniline monomer in the colloid solution obtained from section 2.1. During this process, aniline-DBSA is added to the Ag-PVA colloidal solution, followed by addition of the aqueous APS solution dropwise. The resulting blend mixture is left to react for 24 h under constant stirring at 5–10 °C. The colloidal solution obtained are used to prepare thin film on glass slide and interdigitated gold electrode washed with DI water and acetone and dried. Keeping the other concentrations and methods constant four different PPVA-Ag nanocomposites are prepared with 0.5, 1.0,1.5 and 2.0 M of AgNO3.
Figure 1: Steps followed to prepare PANI-Ag nanocomposites 2.3. Study of Effect of humidity on the PPVA-Ag nanocomposites A homemade setup is used to study of effect of humidity on the PPVA-Ag nanocomposites coated on the interdigited gold electrode fingers using dropcast method. The humidity chamber consists of transparent polymer with three holes for nitrogen gas inlet, humidity inlet and electrical wires for conductivity measurement. The schematic diagram of the setup is shown in the Figure 2. Humidity meter and the polymer coated electrodes are placed inside the chamber. The control of humidity inside the chamber has been done using humidifier and N2 gas during the experiment. And keithley sourcemeter 2400 has been used to measure the resistivity.
Figure 2: Schematic diagram of humidity measurement setup 3.1 Scanning Electron Microscopy studies The results of surface morphology analysis using SEM are shown in Figure 3. From the images it is seen that Ag nanoparticles are well dispersed in PANI-PVA matrix. Such results are observed because chemical method of preparation has been adopted. With the increase of Ag concentration there are not much changes in the particle size, however the degree of agglomeration increase, that causes the increase in surface roughness.
Figure 3: SEM images of (a) PPVA-Ag-0.5, (b) PPVA-Ag-1.0, (c) PPVA-Ag-1.5 and (d) PPVA-Ag-2.0. 3.2 Effect of Humidity We have used all the four types of composites for this measurement. For this measure at first the humidity chamber is blown with N2 gas for few minutes to reduce the humidity to RH 20 % at room temperature. Once the reading in the humidity meter is stable, resistance of the thin film has been measured. Each time for resistance measurement voltage reading for 10 mA current has been repeated for 10 times with time sweep of 500 ms. In order to reduce the error we repeated the whole measurement for 15 times at each RH measured, shown in Figure 4 for PPVA-Ag 1.0M sample. During the experimental process each step is maintained at constant parameters till the electrical signals reading reached a steady value. All the four plots describing resistance change as a function of humidity for each composite measured has been shown in inset of Figure 4. It is has been observed that, there is not much difference between the resistance curves as a function humidity for all the four composites. As the humidity increases water vapour contributes to the reducing the conductivity in two ways, firstly water molecules donate electrons to the valence band of PANI molecules, therefore decreasing the number of holes and increasing the bandgap and secondly as PVA is hydrophilic, so it absorbs water molecules and get expanded, this leads to increase the interparticular distances between the conducting fillers of the composites, and reducing the conductivity. Because of these two reasons higher the RH level lower the electrical conductivity.
Figure 4: The effect of Relative humidity on the resistance of PPVA-Ag-1.0M, Inset The effect of Relative humidity on the resistance of four PPVA-Ag samples.4. Reference: [1] M. Joulazadeh, A. H. Navarchian, Advances in Polymer Technology, 33, 2014, 21461. [2] A. T. Ramaprasad, V. Rao, Sens. Actuat. B, 148, 2010, 117–125. [3] J. Wang, X. Wang, X. Wang, Sens. Actuat. B, 108, 2005, 445–449
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Environmental Evaluation Risk Assessment and Management options of Abu Nakhla Treated Sewage Effluent TSE Unlined Pond Doha Qatar
The rapid economic and population growth of Qatar during the last few decades led to generation of substantial volume of municipal treated sewage effluent (TSE). Most of this water was disposed into Abu Nakhla depression at the outskirt of Doha city since 1985. Abu Nakhla depression is situated at the south-west of Doha. The mixture of these effluents with surface and ground waters during rainy seasons created a conspicuous water body of around 2 by 3 km. For many years, this pond was the source of many adverse environmental effects such as bad odor, vermin and elevated groundwater levels in the neighboring residential areas. The claims that some of the disposed water was untreated aggravated the situation and the local community considered the pond as impure body of water. A multiproxy study was carried out during 2014 and 2015, including remote sensing, geological, geophysical (resistivity-tomography) and geotechnical investigation of the pond origin and evolution. Hydrogeological and hydrochemical analyses of water samples collected from 24 observation wells drilled around the pond. These studies revealed that, the upper part of the subsurface geology of the pond site is composed of Tertiary carbonate rocks of the Simsima/Umm Bab member and Midra shale member of the Dammam Formation, which is underlain by the Rus Formation, both of Eocene age. In Qatar, the Simsima/Umm Bab member represents the shallow groundwater aquifer, while the Rus is the upper principal aquifer. The upper part of the Simsima/Umm Bab member is characterized by the presence weathered weak zones, cracks and fissures, which enable infiltration of the pond water to recharge the aquifers. The pond has a rich and diverse population birds, fish and frogs, hosting about 260 bird species, such as 150+ Greater Flamingo (Phoenicopterus roseus). It also hosts about 10% of the total plants species in Qatar, such as: Phragmites australis, Typha dominguensis. Water analyses have shown that, the water in the pond was of good quality, in terms of physiochemistry and biological and microbial contaminants. This is due to Qatar's use of advanced wastewater treatment technologies, with ultrafiltration and ultraviolet (UV). Heavy metals concentration in the water of the pond, was very low. Analyses conducted in May 2014 indicate that most of the heavy metals levels were below the international FAO limits for irrigation water (FAO,1985), such as: Ni concentration was 2.4 mgL-1, FAO limit is 200 mgL-1. As concentration was 1.0 mgL-1, FAO limit is 100 mgL-1. Pb concentration was 0.8 mgL-1, FAO limit is 5000 mgL-1. Cd concentration was 0.0 mgL-1, FAO limit is 10 mgL-1. The results of our 3D groundwater numerical modelling, indicated the loses of about 5% of the pond water per day, due to high infiltration and evaporation rate. This causes the rising of water table in the neighboring areas. The pond represents a breeding ground for mosquitos. The presence of snails may also act as incubators for some parasites. Management options of the pond site, have been recommended. These include, changing the area into natural reserve, artificial oasis, and can serve as a meteorological station.
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Cost of energy inefficiency in Qatar
By Athar KamalEnergy policy and security of a country heavily depends on its resources, geography, demographics and economic structure. While most active strategies include the discovery, extraction and utilization (through new infrastructure) of energy resources, a more subtle approach to reduce energy demand and increase energy security is to use the resources more efficiently and conserve them to increase the life span in which they can be used. This understated approach is the implementation of energy efficiency policy. Energy efficiency taken holistically includes the improvements in technology as well as changes in human behavior to do a task with less amount of energy. While different studies have shown the impact of efficiency policies and programs on individual economic sectors (i.e. industrial, commercial, residential, agriculture and transport), a complete overview of the impact of efficiency on economy has received little attention. This approach overlooks the interdependence of each economic sector and their influence on each other. Similarly, the rebound effect, a consequence and a major element of efficiency is avoided in these studies as well. Rebound effect is the increase in energy consumption because of lower prices of energy commodities due to increase in efficiency. The rebound effect not only has a direct impact on the individual sector, like driving more miles because of a more efficient vehicle, it has also indirect consequences, such as going to a vacation because of the money being saved through efficiency. Thus, the study of efficiency, its dynamic influence and calculating a realistic magnitude are required to ideally approach the costs and benefits of implementing an efficiency program or policy. This research looks into the economy wide impacts of energy efficiency and the dynamic interaction and impacts of each sector on the other. First, a hierarchal list of variables, which influence the energy supply and demand of any economy, is created. Second, a list of indicators which measure the health of an economy is formed. Using data for the top 10, oil and gas producing countries (these countries give a good mix of economies which heavily rely on oil and gas rents such as Qatar, UAE, Saudi Arabia as well as economies, which produce some of the highest energy resources, while relying very little on its influence on their economies, such as US, Norway), the magnitude and impact of each variable to the economy is calculated. These variables are then used to create a system dynamics model which includes the production, conversion and transportation of energy from different sources to consumption in different sectors. Estimated energy efficiency measures and impacts are then incorporated into the systems model to see the effect of efficiency as well as the rebound effect on the economy. A major goal of this study is to find the future impacts of energy efficiency policies and the consequences of these policies, if they are not implemented because of financial constraints or present gains (such as more revenues from greater resource production). The cost benefits as well as the effective implementation of efficiency measures are calculated and compared using the economic indicators obtained in the second step. Finally, these indicators can be used to determine as to why some countries are more efficient with their energy resources as compared to others.
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Plasmonically Enhanced Schottky Solar Cell
Authors: MOHAMED Farhat, Sabre Kais and Fahhad AlharbiPlasmonics is an emerging broad area of research, which studies the exceptional optical properties of metallic 2D and 3D nano-structures, i.e. confinement of electromagnetic waves (surface plasmon polaritons) [1]. During the past years, there has been a huge interest in employing plasmonic structures for sunlight harvesting [2], i.e. for example in thermal photovoltaics, thin-film solar cells, or solar thermoelectrics, etc. All these applications exploit the exceptional capabilities of plasmonic structures to concentrate electromagnetic energy and generate “hot” electrons. In this proposal [3], we aim to use plasmonic light confinement to build Schottky solar cells. The photovoltaic effect in these cells is induced by the metal (insulator) semiconductor interface (see figure below). And the presence of the plasmonic metal will increase the generated current in the active silicon layer and thus increase the overall efficiency of the cell.We wish to stress here that previous works using the plasmonic effect in solar cells, considered mainly the p-n junction [4], except the one using graphene with another semiconductor but not considering plasmonic effects [5]. In addition, we should mention, that the mechanism of the cell proposed here is intrinsically different from hot-electrons based plasmonic solar cells [6]. The novelty of this work is to use metallic strips for two functions simultaneously, i.e. as contact for electrons and as junction (Schottky barrier between metal and semiconductor). This permits a good efficiency with very simple structure (no need for having expensive semiconductor nor both doping, i.e. p and n for Silicon).We will discuss limitations and potentials of this kind of solar cells, in particular ease of fabrication.
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Enhancing District Cooling Plants Efficiency in Qatar Using Desiccant Air Dehumidification
More LessEnergy consumption for air conditioning purposes accounts for 60-80% of electricity used in Qatar. As District Cooling Plants (DCPs) has a potential to reduce energy consumption and CO2 emissions, Qatar and GCC are continuously shifting paradigm towards adoption of DC plants to satisfy the rapidly growing demand in all sectors. However, DC plants usually rely on wet cooling towers for disposing the excess heat to the ambient. Hence the efficiency of DCPs is significantly influenced by the cooling tower effectiveness in heat disposal, which is dominated by latent heat or evaporation of water in a counter atmospheric current air stream. Operation district cooling plants (DCPs) under extremely high humidity in summer represents one of the major thermodynamic limitations in terms of maintain the outlet water temperature of cooling towers (i.e. chiller's condenser cooling water) as low as possible to guarantee higher efficiency of DCPs. The cooling tower efficiency degrades considerably at higher relative humidity of air, which approaches saturation limits in summer, where the cooling demand is high. The ambient wet-bulb (WB) temperature is a limiting factor for the capacity of cooling towers (CT), which determines the inlet cooling water temperature to the chiller's condenser (outlet water temperature from the CT). Due to prevailing weather conditions in Qatar and GCC, this temperature is designed based on 31 °C WB temperature in summer, which result in a 34 °C inlet condenser cooling water temperature. This represents a thermodynamic limitation to reduce the energy consumption of chillers, which lies under the focus of this study. Desiccant cooling is an environmentally attractive alternative to conventional mechanical air-conditioning, especially for air dehumidification purposes. It does not require ozone depleting refrigerants and it can be run off low temperature solar heat or waste heat. The electrical coefficient of performance of desiccant cooling can be above 20, making it over 6 times more efficient than conventional air cooled vapor compression system. This project seeks to develop new processes to reduce air humidity and WB temperature by around 6 °C prior to entering the CT to break the above mentioned thermodynamic limitation. Air dehumidification takes place using liquid to air membrane (3-fluid LAMEEs) for further dehumidification of air. A hybrid solar PV-Thermal system is used for regeneration of both desiccant systems. Lumped and numerical analysis has been conducted using COMSOL Multiphysics software to predict the outlet air temperature and humidity for 3-fluid LAMEEs when used for air cooling and dehumidifying. Results of the numerical and lumped analysis showed that the 3-fluid LAMEE alone can effectively decrease the humidity content of ambient air by up to 40%, while the outlet air temperature can be reduced by 6 °C. Accordingly, the inlet cooling water temperature to the chiller's condenser (outlet water temperature from the CT) can be reduced to 27-28 C, which provides a potential saving of around 25% in energy consumption of the Chiller in district cooling plants.
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Passive Thermal Management of Photovoltaic Modules in Qatar by Utilizing PCMMatrix Absorbers
More LessPerformance and reliability is essential factor for deploying the solar Photovoltaic (PV) technology in desert environment due to the high ambient temperature and high humidity. During daytime, the PV conversion efficiency decreases considerably due to high temperature and weak natural cooling effects on PV modules. During night, sky radiation cooling promotes atmospheric water vapor condensation on PV modules surface, where dust accumulates and consequently, leading to cementation of dust that necessitates manual or mechanical cleaning in absence of rainfall. Therefore, thermal management in hot climates is crucial for reliable application of PV systems to prevent the efficiency drop due to high temperature rise during day time and to keep the module temperature above the dew point during night time to avoid mud formation on PV modules surface. Thermal management of PV modules in hot climates can be achieved by either active or passive cooling. Active cooling includes air-cooling, through natural or forced air flow, and water cooling. In hot summer, air-cooling would be less effective as the ambient temperature reaches up to 50°C, hence water cooling or passive thermal management of PV cells become a necessity. The present research focuses on utilization of Phase Change Materials (PCM) for passive thermal management of solar PV systems. The main focus is to explore the effect of utilization of PCM-based cooling elements on the thermal behavior of solar PV modules. By attaching PCM-Absorbers to the back side of PV modules, the modules temperature can be regulated by the virtue of PCM to extract and accumulate heat at high density, as PCM have a high specific heat density capacity due to latent heat of fusion during melting and solidification. Moreover, the PCM absorber can help reducing atmospheric water vapor condensation during night on the surface of PV module by releasing the absorbed thermal energy during the daytime to keep the PV module on a temperature above the dew point. Some of the important advantages of the proposed solution include, simplicity, no moving parts such as coolant circulation pumps or air blowers are needed, low tech and can be manufactured locally from aluminum waste and oil waste, zero self-energy consumption, involves no hazards such as chemical toxicity, flammability or explosivity, and has a longer life time than the life span of top quality PV modules available in the international market. The PV module and PCM material have been modelled using Finite Element method in COMSOL Multiphysics software. A macro scale transient model has been developed to capture the underlying physics related to energy and heat transfer balances. The setup contains six main sections; transparent top glass cover, PV cells, aluminum back sheet, heat conduction film, PCM matrix absorber and aluminum heat fins. The effect of PCM thickness, i.e. heat storage capacity, PCM melting temperature, fiber porosity and thermal conductivity of matrix absorber with/without heat fins has been extensively studied. The numerical simulation results showed that there are optimum thermos-physical properties for PCM Absorbers for cooling of PV modules under Qatar weather conditions. It has been concluded that the ideal PCM-Absorber should have a melting temperatures of 53–54 °C, 30 mm PCM thickness, and 85 % fiber porosity of metallic aluminum fiber structure and with aluminum heat fins. With the optimum design of PCM-Absorber, the PV module's peak temperature can be reduced by 16 °C during daytime and at night it can be maintained at 3-5 °C higher than conventional modules, which reduces water vapor condensation tendency. Furthermore, depending on the temperature coefficient of a PV module, the power production can be increased by up to 6–8% for mono and poly crystalline cells respectively, and up to 5% for thin film technology. The module's instantaneous efficiency can be increased by 1–2%. In addition, study of the effect of passive thermal management on PV modules lifetime is ongoing and preliminary results revealed that a significant increase in lifetime would be expected. A techno-economic analysis for commercial scale application of the proposed thermal management solution has also revealed promising results, especially under local manufacturing in Qatar utilizing oil waste, which makes it economically viable.
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Passive House Design Alternatives for Labor Camps in Modern AgroIndustrial Communities in Qatar
More LessThe consumption of electricity in residential buildings exceeds 20% in Qatar and can go up to 50% in other hot countries like Kuwait. The air-conditioning systems in hot countries like Qatar consumes around 60–80% of the total energy demand in buildings. This triggers researchers and industry experts in the built environment to explore new avenues towards reducing the cooling load on a building and study influential factors to enhance energy efficiency in buildings in such extreme climatic conditions. The carbon foot print of buildings can be reduced by reducing the cooling load through passive building design, using high efficiency equipment and incorporating renewable energy technologies such as solar systems, air source heat pumps, wind generators and ground source heat pumps are few to name that are widely used among many other available renewable technologies. The focus of this research work is on the Passivehouse building design incorporating solar hybrid Photovoltaic Thermal collectors (PV/T) as a source of renewable electricity and solar hot water for domestic use. Two different designs of a residential building for Modern Agro-Industrial Communities in Qatar were considered i.e. Pyramidal Shaped Building and Square Shaped Building. 3D energy models were created for both type of buildings using the IES software (Integrated Environmental Solutions) in virtual environment and thermal analysis was carried out. For the same building type, orientation and structure, two different criteria were applied to the model i.e. Passivehouse design vs. Conventional design. Pyramid shaped buildings are more stable but tend to cost more to construct when compared to traditional buildings. The sloping external walls tend to gain more solar energy and daylight through windows installed on the external walls. This provides an opportunity for solar panels installation on the external walls. The solar gain through external windows can be reduced to a minimum by effective solar shading and the daylight harvesting system can further reduce the artificial lighting gain inside the building. The results show that the passive house design of a building can save more than 70% of the cooling plant load, the as installed plant size and associated infrastructure. This will also considerably reduce the annual operational and maintenance cost of the building with just an extra 15% in construction cost. The cost analysis of passive house in comparison with a conventional house was carried out by QGBC (Qatar Green Building Council). In a nutshell this research work demonstrates how buildings' cooling load and carbon foot print can be reduced by effective solar shading, lower infiltration rates (air tight building design), highly insulated building fabric, natural ventilation, daylight harvesting system (that can help reduce artificial lighting gain inside the building) and heat recovery system.
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Compartmentalization and production allocation study of a carbonate field using molecular fingerprinting
Authors: Frank Haeseler, Damien Couteyen-Carpaye and Fatima MahdaouiIn multi layered reservoirs the fluid composition may differ from one layer to another. The knowledge of the lateral and vertical fluid heterogeneities may help to better understand the fluid distribution in the field and consequently contribute to enlighten production. Several mechanisms can affect the fluid composition, like origin, maturity, alteration or physical conditions. The objective of this study is to present a methodology aiming at characterizing and quantifying the compositional differences between fluids from different layers in an oil reservoir. It allows mapping the vertical and lateral heterogeneities in fluid composition. In order to measure the hydrocarbon composition, samples are analyzed by HRGC (High Resolution Gas Chromatography). In a first step this method aims at finding the peak ratios discriminating the oils from different reservoirs. Data are processed for peak recognition and statistical comparison is performed to compare samples. This statistical interpretation allows identifying similarities and differences between chromatograms e.g. oils. The results allowed identification of two end members. All the other samples of the field could be described as a mixture of these two fluids. Different cross-sections have been analyzed aiming at better understanding the field by linking geochemical data with geological features. By coupling the result with geological (lithology, cross-sections, logs…) and reservoir data (porosity, permeability, saturation…), different explanations could be proposed: Possibility of having different end members originating from a same fluid.Water washing as a possible process affecting fluids from different layers in similar and continuous way.“Structural heights” susceptible to reduce the water washing effect for some wells.The dip of the layers might increase water washing effect on fluids. This study showed the possibility to allocate the production in a carbonate field and allowed a better understanding of the fluids distribution. The molecular fingerprinting made it possible to understand the origin of fluids in comingled wells and particularly to identify the most producing part of the well in horizontal drains.
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Application of Value Engineering approach for Improving the Quality and Productivity of Ready Mixed Concrete Used in Construction and Hydraulic Projects
More LessThe paper studies the effectiveness of applying value engineering to concrete mixtures. It was conducted in the State of Qatar on a number of strategic construction projects for the 2022 World Cup projects, in order to generally improve the quality and productivity of ready-mixed concrete used in construction and hydraulic projects. The application of value engineering to such concrete mixtures resulted in the following: Improving the quality of concrete mixtures and increasing the durability of buildings; Optimizing the use of resources, and enhancing sustainability; Reducing the use of cement, thus reducing CO2 emissions which ensure the protection of environment and public health; And Increasing the market share and competitiveness of concrete producers The research shows that applying of value engineering to concrete is an effective way to save around 5% of the total costs of concrete mixtures and, in turn, reducing the costs of construction projects.
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Heterojunction Solar Cells Exceeding 20% Efficiency Using Gettered Monolike Silicon Wafers
Silicon heterojunction (SHJ) solar modules are an attractive and suitable option for application in high temperature environment such as in the state of Qatar. This is mainly related to their high open-circuit voltage (Voc) [1], which is essential for achieving better performance at high temperatures. High efficiency SHJ solar cells are usually made from high-quality n-type monocrystalline silicon wafers, which increases the cost of the device. If lower-cost materials such as high performance multicrystalline and mono-like silicon wafers could be used, significant reduction in the cost of PV electricity can be achieved. In this work, electrical properties of industrial-scale n-type and p-type mono-like silicon wafers have been investigated for use in high efficiency SHJ solar cells. The wafer's electrical resistivity were measured by four-point probe as 1–3 Ω-cm for n-type and ∼1 Ω-cm for p-type wafers. Since minority carrier lifetimes in as-grown (un-gettered) cast silicon, including mono-like silicon is usually low (i.e. inadequate for application in high efficiency solar cells), phosphorus diffusion gettering in a POCl3 furnace and/or bulk passivation by SiNx:H were used for enhancement of electrical properties. SHJ solar cells were then fabricated using the gettered wafers and as-grown sister wafers to assess the effectiveness of the gettering treatments. Figure 1. Injection dependent minority carrier lifetime for as-grown wafers and for gettered sister-wafers, after passivation with i/n and i/p amorphous silicon layers Figures. 1 shows minority carrier lifetimes measured by Quasi Stead-State Photoconductivity (QSSPC), on wafers as-grown, gettered and gettered with SiNx:H bulk passivation. As-grown lifetimes are low, being < 170 μs for p-type wafers and < 370 μs for n-type wafers, at 1 × 1015 cm-3 injection level. After passivation, significant improvement (up to 520 μs for p-type and 1900 μs for n-type) was achieved at 1 × 1015 cm-3 injection level. Despite the significant enhancement in overall lifetime, lifetimes at low-injection level is still limited, particularly for the p-type silicon. Nevertheless, very high carrier lifetime (up to 2400 μs) was recorded at 1 × 1015 cm-3 injection level (Figure 1(a)), and a SHJ cell with VOC of 720 mV and a photo-conversion efficiency of 20.3 % were successfully achieved, by gettering and bulk passivation. In conclusion, we demonstrated that electrical properties of industrial-scale mono-like silicon wafers can be efficiently optimized by gettering and bulk passivation treatments for application in high efficiency solar cells. A silicon heterojunction solar cell with efficiency exceeding 20% was produced. References [1] S. De Wolf, A. Descoeudres, Z. C. Holman, and C. Ballif, «High-efficiency silicon heterojunction solar cells: A review,» Green, vol. 2, pp. 7–24, 2012.
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A Noval Self Healing Control System for Next Generation Electric Grid with Big Data Platform
Authors: Shady Khalil, Mostafa Shahin, amira Mohamed and Haitham Abu-RubNowadays, many electrical utilities are moving towards self-healing distribution grid. This is realized by adding to distribution system various sensors, intelligent electronic devices (IEDs), phasor measurement units (PMU), sequence of event recorders (SERs), reclosers, detectors, measurement units, automated controllers, and other automation equipment. Those elements provide a continuous stream of data to support grid performance and improve its reliability. Huge amount of data obtained from different smart grid sources satisfy all the Big Data (BD) characteristics. The success of future electric grid depends mainly on the effective utilization of the huge amount of the data flow. This mass of information is essential to make next generation electric grid more efficient, reliable, secure, independent, and supportive during normal conditions and contingencies. The self-healing grid requires a robust real-time computation system that monitors, processes, provides predictive analytics, performs data mining and statistics, and makes faster decisions of the diverse and complex data collected within the traditional and nextgeneration electric grid. This helps to detect, locate, and isolate various faults, reconfigure and reroute power of the distribution network to minimize service disruptions and outages.Implementation of self-healing control system is associated with big data utilization which is a persisting challenge. Computational complexity challenges is associated with processing huge amounts of data during operation of the electric power system. Therefore, this paper presents acomprehensive studies of the impact of implementing a smart real-time dynamic self-healing control strategy using BD process platform with deep learning technique on the distribution system for current grid and future smart grid. The deep learning technique is a subfield of machine learning. The deep learning is shown to be highly efficient solution for the analysis of massive amounts of data which is performed by discovering and utilizing available regularities in the inputs to help self-healing control system to network reconfiguration, and coordination of various distributed energy resourcesin the smart grid. The deep learning system complexity does notdepend on the number of grid buses, this is because the power flow solving time is approximately linear with respect to the number of system buses. However, the complexity of the system depends on the number of the system inputs. The Long Short Term Memory (LSTM) recurrent neural network will be used in modeling sequential data such as time series data. Such network has the ability to learn contextual information over the history of the input sequence. The BD analyticswill be used as a key to deal with the uncertainties and different sizes of structured and unstructured data. The advanced analytics techniques such as predictive analytics, in addition to data mining, statistics, and faster decisions making will be utilized for data coming from sensors within the traditional and next-generation electric grid. The studies performed are based on real-time monitoring and control of the network topology and operating conditions taking into account different power sources and hybrid renewable energy sources which usually have different characteristics on the electric power grid. Finally, the real-time implementations of the proposed system will achieve dynamic resources optimization, network reconfiguration, and optimum operation of power grid using LSTM with big data platform.
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Synthesis and Properties of Novel NiBAlN Nanocomposite Coatings
Degradation of materails due to corrosion has now emerged as an international challenge which is compelling the community to trace out some smart solutions on priority basis. Corrosion mitigation is not only important as it results in wastage of our natural resources, time, money and efforts, but more importantly its inadequate handling may lead to the safety threats. Some, such sad incidents have been reported in the past. That is why many countries of the world are paying special attention to address this challenge by investing a lot of money. Although, we can notice corrosion everywhere around us, however, mining, mineral processing, oil & gas and many other processing industries are facing severe corrosion challenges. In many applications, it is only the surface of the material that is directly exposed to the corrosive medium, hence modifying the surface properties may lead to control the corrosion phenomenon. Towards this goal, the development of various types of nanocomposite coatings has proven to be a an economic and viable option. The present research work addresses the synthesis and characterization of novel Ni-B-AlN nanocomposite coatings. The Ni-B and Ni-B-AlN nanocomposite coatings were electrodeposited on the mild substrate. A comparison of structural, surface, mechanical and electrochemical properties are presented to elucidate the beneficial role of the incorporation of AlN nanoparticles into the Ni-B matrix. We have noticed that the addition of AlN nanoparticles to Ni-B matrix has a remarkable effect on its properties. Ni-B-AlN nanocomposite coatings demonstrate superior structural, mechanical and anticorrosion properties when compared to Ni-B coatings which make them attractive for many industrial applications.
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GridConnected CapacitorTapped MultiModule Voltage Source Converter
Authors: Ahmed Abbas Elserougi, Shehab Ahmed and Ahmed MassoudIn this work, a new dc-ac converter is proposed for grid integration purposes, namely, capacitor-tapped multi-module dc-ac voltage source converter. The main advantages of the proposed converter when compared with the conventional dc-ac modular multilevel converter (assuming the same voltage rating of semiconductor devices) are: (i) employment of a lower number of semiconductor devices, but with a higher current rating hence it provides operation with a lower number of gate driver circuits, and (ii) employment of a lower number of dc capacitors which reduces the number of measured variables, which affects positively the cost and reduces the computational burden of the employed controller.
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Solar Thermal System for Heating and Cooling Requirements of Commercial Building in Doha: A Case Study
Authors: shoukat alim Khan, Majid Aziz and Muammer KocThe demand for cooling in Gulf region is the direct effect of its high atmospheric temperature. Around 60% of the electricity demand in GCC is for cooling purpose. The main source of cooling and air-conditioning in these countries are conventional electric compression cycle, which leads to the increase in the GHG emission, directly in the form of leaked gases from these systems and indirectly in the form of fossil fuel used for the production of the used electricity for these systems. Solar energy in general and solar thermal energy specifically can be a promising and sustainable solution to the cooling and air-conditioning requirement for the buildings in Qatar and GCC. Absorption cooling and air-conditioning is a mature and promising technology with respect to its efficiency and results on the industrial scale. However, the use of technology with solar thermal energy is new in the market. In this paper, the feasibility analysis of solar thermal technology has been done for the cooling, heating and hot water requirement of a commercial building in Doha, Qatar. Heating and hot water requirement for winter and cooling requirement for summer season were calculated and used as a load. Solar thermal collectors (STC) were used as the main source of thermal energy collection form sunlight. Along with STC, thermally driven adsorption chiller was designed to fulfill the cooling requirement in the summer season. The design and selection of the different components and parameters such as Solar thermal collector area, storage tank size, adsorption chiller etc. have been done in detail. The result, obtained for building's energy demand and its supply from the designed solar thermal system, gives a clear sign for the successful implementation of this technology.
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Counting the Carbon: Assessing Qatar's Carbon Dioxide Emissions
Authors: Mona Al-Asmakh and Nadya Al-AwainatiClimate change is the most pressing global environmental issue today, with a potentially devastating impact on human development. According to the Intergovernmental Panel on Climate Change (IPCC) reports, Qatar is ranked as the highest CO2 per capita emitter globally. Qatar is contributing to the reductions of anthropogenic carbon dioxide (CO2) by supplying the world with Liquid Natural Gas (LNG), yet Qatar is being negatively imaged as highest CO2 per capita emitter. The reading of the highest CO2per capita has affected Qatar's ability to attract green investments and to improve the country's attraction in the tourism market. Qatar's position as the leader CO2 per capita has made it unattractive for investors both internally and externally because of the perception that the investment would not be ‘green’. The per capita emissions are a result of two main factors: the total absolute emissions and the total population. Two major and significant factors, consumption and population, should be taken into consideration when discussing the total absolute emissions for Qatar: The assumption for this equation is that the population uses all the produced energy, which is the denominator. This assumption is a disadvantage to Qatar due both to its low population and the fact that it is an energy producer. CO2emission would be much lower for Qatar if a consumption-based accounting system was used for the calculation of the per capita value. The use of emissions accounting measure is of vital importance to individual countries. There are two feasible carbon emissions accounting units: production-based accounting and consumption-based accounting systems. Production-based accounting is linked to economic system boundaries (greenhouse gas emissions from resident institutional units, analogous to gross domestic product). It involves measuring the emissions occurring within a country's boarder and does not take into account production chains extended across boundaries. An illustration of a production-based system examines the emissions generated from fuel purchases and allocates them the country producing the fuel, not the country consuming the fuel (OECD, 2016). While the Consumption based accounting system is related to how much this country emit for its domestic uses. Data are more difficult to obtain for the consumption-based approach because the computations are more complicated to compile as it relies on input-output tables, which includes all steps in production from raw material extraction through the final assembly and ultimately the final sale of the product (General Secretariat for Development Planning, 2009).The controversy comes in determining responsibility: is it the player initiating the polluting process (consumer) or the player producing the pollution (producer)? Consumption-based measures are preferred by developing countries while production-based measures are preferred by developed countries. Qatar is unfairly portrayed as the highest carbon dioxide emitter in the world in terms of per capita measures. Qatar's carbon footprint takes into account Qatar's energy production rather than the country's domestic consumption. The main argument of the paper is to discuss Qatar's CO2 emissions per capita compared to other reporting measures, and to examine the difference between using a consumption based CO2 emissions accounting system versus a production-based one for Qatar. The paper discusses the complications of using a production-based accounting versus a consumption-based accounting system for Qatar carbon dioxide emissions calculations. The research applies both of Quantitative and Qualitative Analysis. The Quantitative analysis is related to roughly re-estimate Qatar's CO2 Per Capita emissions figure based on Consumption based accounting system. The qualitative analysis focuses on creating different comparisons to compare Qatar's CO2 emissions in terms of different reporting measures to three different categories. First category is comparing Qatar's emissions against GCC countries; these countries have the major common attribute that they are mainly dependent on oil and gas revenues, similar demographic location, weather and lifestyle. The analysis outcomes of this category illustrates that KSA has the highest emissions for CO2 intensity and for the absolute emissions. The second comparison category is comparing Qatar's CO2 emissions against major Liquified Natural Gas (LNG) producers which are Australia and Malaysia. These comparisons showed that Australia has the highest emissions of Absolute CO2, CO2 intensity as well as the emissions per GDP. The third category was to compare Qatar's position related to the major global emitters, such as China, India, Russia, and USA. This comparison resulted in China having the highest absolute emissions, CO2Intensity as well as emissions per GDP. The Analysis outcome of the comparisons highlights that Qatar is not the highest CO2emitter in terms of absolute CO2 emissions, emissions intensity, and emissions per GDP compared to the GCC countries, major LNG producers and the world largest emitters. Qatar has the highest CO2 emissions per Capita due to two main factors: Qatar is the largest LNG producer and Qatar has a relatively small population when compared to other countries. Qatar is a developing country, it is the largest LNG exporter and it has third highest natural gas reserves in the world. Qatar makes an indirect contribution to mitigating the impact of climate change, which is done though exporting a clean form of energy, i.e., Liquefied Natural Gas. Even though Qatar is a major contributor for the supplying the world with clean energy, Qatar has taken other initiatives to minimize its carbon emissions. Continuous research and development will be a key element to Qatar overcoming the climate change challenges through Research and Development Centres. In summary, the research paper has four main sections. The first section of the paper includes a background on climate change, its impact and mitigations. The second section discusses Qatar's global position using different CO2 emission reporting measures, including Absolute CO2emissions (kt), CO2emissions per GDP (kg per PPP$ of GDP), CO2intensity (kg per kg of oil equivalent energy use), CO2emissions per capita (metric tons per capita). The third part explores Qatar's CO2 per capita calculation incorporating the consumption-based accounting system and assessing the complications of using a production-based accounting versus a consumption-based accounting system for Qatar carbon dioxide emissions calculations. The last section covers Qatar's clean initiatives and offers recommendation towards net zero emissions and improving Qatar sustainability figures.
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Production of hazardous gas sensors using spinel ferrite nanoparticles
Authors: Jocelyn Ayesh and Mohammad Abu HaijaThis work reports on sensitive and selective gas sensors based on copper ferrite (CuFe2O4) nanoparticles. The nanoparticles were produced different methods including: colloid microwave assisted hydrothermal method, and co-precipitation method. Those methods enable a precise control of nanoparticle size, The produced nanoparticles were annealed at different temperatures. Structural analysis were carried out using x-ray diffraction (XRD) and transmission electron microscopy (TEM), and they revealed that the asprepared nanoparticle exhibit cubic structure. The nanoparticles undergo crystal structure transformation to tetragonal structure upon annealing. Furthermore, the nanoparticle were found to grow in size upon annealing. The tetrahedral and octahedral absorption bands which are characteristic of the spinel ferrite were determined using Fourier Transform Infra-Red Spectroscopy (FTIR) measurements. Gas sensors were fabricate by pressing the produced nanoparticle powder into disks. The sensor device was produced utilizing capacitor structure, with the top electrode stainless steel of grid structure. The produced sensors were characterized to be sensitive to both H2S and H2 gases, with greater sensitivity to H2S at low temperatures, where these sensors could detect H2S concentrations of 10 ppm at 80°C. The low optimal operation temperature reveals the low power requirements for sensor operation. Thus, those sensors exhibit the potential to be used for industrial applications, especially for the petrochemical industry the Petroleum Institute under a grant number RIFP-14312 and Qatar University.
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A new ELLAM implementation for modeling solute transport in fractured porous media
Authors: Fanilo Heninkaja Ramasomanana, Marwan Fahs, Husam Baalousha, Nicolas Barth and Said AhziThe fluid flow and solute transport through fractures in rocks are processes that have importance for many areas of the geosciences, ranging from groundwater hydrology to petroleum engineering. It is well known that fractures play an important role in flow and transport processes through geologic formation and number of environmentally relevant problems require the analysis of mass transport in subsurface systems. As Qatar»s aquifer is Karstic, the development of an appropriate numerical model is necessary to take account the high contrast between the fractures and the porous matrix. Fractures are the set of rock discontinuities that can occur in geological formations at different scales. They intensively affect the transport processes because they represent the preferential flow and mass migration paths. In this study, we introduce an adaptation of the Eulerian Lagrangian Localized Adjoint Method (ELLAM) [1] for the simulation of mass transport in fractured porous media. The fractures are represented explicitly using the discrete fracture model (DFM) which handles explicitly the fractures and matrix. It involves describing each fracture individually and discretizing fractures as well as matrix [2]. Specific physical and geometrical properties are imposed for the fractures and matrix domains. This model can be used in the domains where a relatively small number of fractures exist. DFM is the most accurate model because fractures are considered without any simplification. However, this model requires enormous computational time and memory due to the dense meshes resulting from the explicit discretization of the fractures. As a consequence, its use requires highly efficient numerical methods for solving the flow and mass transport. The flow problem is solved using the Mixed Hybrid Finite Element Method (MHFEM) [3] which is well known to be accurate and efficient for complex geometries. It provides consistent and accurate velocity even in highly heterogeneous domain, which is a relevant property for flow in FPM. The obtained velocity field is then used to solve the mass transport problem with ELLAM. ELLAM combines an Eulerian and Lagrangian treatments without any splitting procedure by considering trial functions that depend on time and space. The results obtained by Celia et al. [1] demonstrated the mass conservation of the ELLAM in its formulation and its high computational efficiency compared to classical numerical method. In this work, a new ELLAM implementation is developed to address numerical artifacts (spurious oscillations and numerical dispersion) arising from the high contrast of velocities between fractures and porous matrix. Moreover, the efficiency of the developed ELLAM implementation was improved, taking advantage of the parallel computing on shared memory architecture for the tasks related to particles tracking and linear system resolving. The performance of ELLAM was tested by comparison against the Eulerian discontinuous Galerkin method based on several benchmarks dealing with different fracture configurations. The results highlight the robustness and accuracy of ELLAM, as it allows the use of large time steps, and overcomes the Courant-Friedrichs-Lewy (CFL) restriction. This work contribute to the Aquifer Storage and Recovery (ASR) project of Qatar which aims at artificially storing water in the aquifer for future use by developing an efficient and accurate model for mass transport in fractured porous media. References [1] Celia, M.A., Russell, T.F., Herrera, I., Ewing, R.E.: An Eulerian-Lagrangian localized adjoint method for the advection-diffusion equation. Advances in Water Resources. 13, 187–206 (1990). doi:10.1016/0309-1708(90)90041-2 [2] Karimi-Fard, M., Durlofsky, L.J., Aziz, K.: An Efficient Discrete-Fracture Model Applicable for General-Purpose Reservoir Simulators. SPE Journal. 9, 227–236 (2004). doi:10.2118/88812-PA [3] Younes, A., Ackerer, P., Delay, F.: Mixed finite elements for solving 2-D diffusion-type equations. Reviews of Geophysics. 48, (2010). doi:10.1029/2008RG000277
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Hydrodynamic Modelling of a complex marine system: Application for the Inland Sea Khor AlAdaid Qatar
More LessPhysical Oceanography is the study of the conditions and processes that govern the movement of ocean water, and its interaction with coastal, seafloor, and atmospheric boundaries. Understanding these processes helps to provide deeper insight into various ecological and physical phenomena that affect the earth's near-surface systems. Furthermore, consideration of physical oceanography is critical for sustainable development and effective urban planning, as most human settlements are along coastlines and thus they experience the combined effects of marine weather, waves, tides, and coastal currents. To help understand the response of marine systems to physical forcing, such as changes in temperature, wind, and humidity, computational eco-hydrological models are created. These models seek to mimic the real environment by using both general and site-specific data related to the hydrodynamics and ecological / physical phenomena, which are then combined with mathematical principles to describe a functional ecosystem.
Most modeling software are designed to simulate flow in “normal marine” systems, i.e. relatively deep systems with near-normal seawater salinities. Khor Al-Adaid (including the Inland Sea), Qatar, however, presents a globally unique marine system, as it is aerially extensive, very shallow (mostly less than 5 m), and hyper-saline. It is surrounded by Eocene rock outcrops, sandy sabkhas, and large mobile dunes which migrate into the Inland Sea water. This marine embayment can be divided into three main areas including: (i) an inner lagoon less than 2 m in depth but 53.5 km2 in extent, with salinity reaching 90 ppt in the summer season, (ii) a 74 km2 outer lagoon up to 18 m in depth with typical salinities of 60 ppt in the summer season, and (iii) a linear channel that is about 10 km long, less saline (∼45 ppt), and it is connected to the Arabian Gulf. The varying range in average salinity, depth, and temperature between these three areas, makes the Inland Sea an intricate system, and thus the hydrodynamics of this system cannot be characterized using existing commercial modeling software, which typically handle more homogenous systems.
This work presents a proposed workflow that will be developed through iteration and testing of existing software, which will account for the modeling challenges faced with a complex heterogeneous system like the Inland Sea. As a starting point, GEMSS (Generalized Environmental Modeling System for Surface waters) will be used, as it provides a set of hydrodynamic, sediment transport and water quality modules, and has been used and calibrated previously in various locations around the Qatari coast to date. Comprehensive field data will be collected and processed to help understand the flow dynamics of the system. Measurements will be made using current meters, ADCPs (Acoustic Doppler Current Profiler), tidal gauges as well as temperature and salinity meters deployed throughout the study area. The data will then be used to build and calibrate the model to assess whether the system can be handled as a whole using GEMSS, or if the areas should be subdivided and treated separately.
The findings of this work will act as a stepping stone to help understand current flow dynamics in the system and how these flows shape the salinity profiles and physical structures. In turn, this will offer insight into the important habitat features currently observed in the system, and add better understanding as to how these may be altered naturally and potentially by anthropogenic means.
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Ecogenotoxicological Impact of Marine Pollutants on Qatari Bivalves: An Experimental Approach
Authors: Zenaba Khatir, Radhouane Ben Hamadou, Pedro Range, Hajer Alnaimi and Alexandra LeitãoThe geographical and hydrological characteristics and industrial activities of the Arabian/Persian Gulf contribute to its classification as a stressed marine environment. The persistency of some contaminants released by human activity is putting additional pressure on this already fragile system. Several studies have assessed the chemical contamination levels in Qatari coastal sediments but this is one of a few studies that assessed their eco-genotoxicological impacts, by using cytogenetic endpoints in a local model bivalve species. Bivalves were specifically selected for this study due to their role as filter feeders, high tolerance for harsh environmental conditions, and availability around Qatar. In this project, determination of Polycyclic Aromatic Hydrocarbons (PAHs), Total Petroleum Hydrocarbons (TPHs) and trace metals in surface sediments and pearl oyster -Pinctada radiata- was conducted in samples collected from 3 coastal locations in Qatar: Umm Bab, Dukhan and Al-Wakra. The selected sites were expected to be dissimilar in regard to the chemical pollutant level and contaminants distribution due to the different anthropogenic activities. Initial aneuploidy levels –numerical abnormality in chromosomes- in oysters were examined between December 2015 to February 2016 through randomly selecting 140 well spread metaphases. Metaphases with 26 chromosomes were recorded as diploid or normal and the ones with less or more number of chromosomes considered aneuploidy (Ebied, 1999). The ability of the oysters to adapt in terms of chemical contaminants accumulation and aneuploidy level when moved between sites with different levels of chemical pollution was assessed in the second sampling in April 2016, and using experimental approach with three treatments (control, transplanted, and translocated). The control treatments were collected from the original site and kept there, the transplanted treatments consisted of individuals composed from the other two sites and moved to Al-Wakra and the opposite, while the translocated treatment were the ones moved from Dukhan to Umm Bab and versa vise. Statistical analysis showed significant difference between sediment in the three sites; TPHs concentrated in Umm Bab, higher concentrations of metals found in Dukhan, while PAHs concentrated the most in AL-Wakra. Hydrocarbons and metals were detected in higher doses in oyster tissues collected in first sampling comparing to those analyzed in the second sampling with consistency of accumulating same contaminants. Predation by gastropod whelks caused high mortality of oyster during the second stage of the study especially in Dukhan control while transplanted animals from Al-Wakra were the least selected by gastropods. Mortality rates in Dukhan were generally higher than in other sites, except for oysters transplanted from Al-Wakra to Dukhan. Positive correlation was found between the high levels of contaminants and aneuploidy during the first phase. Unexpectedly, to the usually observed in bivalves, there was a bigger percentage of abnormal cells with chromosomal gain (hyperdiploids) than with chromosomal loss (hypodiploids) in all treatments. Among all the treatments, transplanted oysters showed the lowest level of aneuploidy followed by translocated, then control. In other words: oysters moved from site to another, regardless of the contamination levels at origin and destination, showed some recovery from initial aneuploidy levels. Further research is needed to determine the underlying mechanisms for this pattern.
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Immobilized Nanosize ZrMetal Organic Frameworks ZrMOFs: Highly Active Reusable Catalysts for Cross Coupling Reactions
More LessFunctionalized Zr-based metal-organic frameworks (UiO-66-fun) have emerged as promising class of porous functional materials with very large specific surface area, ultrahigh porosity and chemical tunability as well as high stability in water and humid environments, which results in desirable properties for several catalytic applications.1–3 These high stable materials were selected as supporting molecular MOF catalysts. We have applied a simple and highly efficient method for synthetic post-functionalization of new and readily recoverable molecular catalysts that combines the catalytic active transition-metal complexes with the architecture of nano-size MOF and their application for cross coupling reactions. In the catalytic process, substituted aryl halides and arylboronic acids converted into corresponding biaryls through C-C bond forming process in a milder condition (Chart 1). In the tested catalysis reactions, functionalized nano-size UiO-66-fun catalysts can be recovered by simple filtration/centrifugation in air and reusable without significant loss of catalytic activity and while framework structures are maintained stable. The detailed post-functionalization and catalysis results will be presented. References: Kim, M.; Cahill, J. F.; Fei, H.; Prather, K. A.; Cohen, S. M. J. Am. Chem. Soc. 2012, 134, 18082.Bosch, M.; Yuan, S.; Rutledge, W. Zhou, H.-C. Acc. Chem. Res. 2017, ASAP, DOI: 10.1021/acs.accounts.6b00457. Pascanu, V.; Yao, Q.; Bermejo Gomez, A.; Gustafsson, M.; Yun, Y.; Wan, W.; Samain, L.; Zou, X.; Martin-Matute, B. Chem. - Eur. J. 2013, 19, 17483. Acknowledgment: Support of this research by the NPRP award (NPRP 9-377-1-080) from the Qatar National Research Fund.
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Environmental Assessment of RO Intakes Applicable for Qatar and the GCC Region
Authors: Hamish R Mackey, Abdulrahman Al-Kaabi and Sami G. AlGhamdiThe State of Qatar and the Gulf Cooperation Council (GCC) region are located in a hyper-arid area with no rivers, over-abstracted groundwater supply and limited rainfall. Consequently, with the discovery of oil and gas and the associated economic prosperity, the State of Qatar and the GCC region have relied on desalination of seawater from the Arabian Gulf. As of 2013, the GCC region held a 70% share of total global desalination capacity.Multi-Stage Flash (MSF) desalination technology has been the source of water supply in the State of Qatar and the GCC region for the past few decades due to the low cost of energy in these countries and the problems historically faced by Reverse Osmosis (RO) membrane processes in dealing wih the high salinity of the Arabian Gulf. MSF is a thermal process that distills water through stages based on high temperature and changing pressures. The systems suffer from high energy requirements and low recovery rates resulting in significant discharge of brine with elevated temperature to the ambient receiving water. RO on the other hand relies on applying a positive pressure to pass permeate through a fine polymer filter material against the osmotic pressure gradient. RO is widely adopted worldwide due to its lower energy consumption and increased product recovery. With recent developments the technology can cover the high salinity of the Arabian Gulf (40,000 mg/L to 55,000 mg/L total dissolved solids). Nevertheless, RO systems require extensive pretreatment to ensure the integrity of the membrane and to prevent blocking of the fine pores. This makes the process susceptible to surface water quality fluctuations such as during algal blooms and therefore its application in Qatar is still challenging due to the shallow and enclosed nature of the Arabian Gulf.Subsurface intake processes for RO have the potential to reduce the effects of fluctuations in source water quality and reduce the energy intensity of the process, since they provide natural filtration of the source water and simplify the extensive pretreatment requirements necessary to protect the RO membranes. However, significant tradeoffs occur by using subsurface intakes. For instance, intake pumping may be increased to overcome the additional headloss through the intake media while the construction phase also involves increased civil works. This research investigates the environmental impacts associated with the operation phase of RO systems using both open intake and beach well intake systems theoretically located in the State of Qatar, since operational phase impacts typically comprise most of the environmental loads in cradle-to-grave assessments.The study utilizes Life Cycle Assessment (LCA) methodology to assess a wide range of effects from the systems. The ReCiPe lifecycle impact indicator approach is utilized with mid-point impact indicators including climate change, marine eutrophication, terrestial acidification, photochemical oxidant formation, particulate matter formation, marine ecotoxicity, water depletion, mineral resource depletion and fossil fuel depletion. The RO system, its pretreatment and intake will be sized and modelled for a desalinated water output of 100,000 m3/d using a combination of fundamental process equations and commercially available software. The results will show a clear direction from an environmental perspective on which type of intake system Qatar should consider if implementing seawater RO as a preferred desalination technique.
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Coral bleaching in extreme environments: speciesspecific thermal tolerance limits
Increasing seawater temperatures are being measured worldwide, causing coral bleaching events during which the symbiosis between the coral host and its symbiotic zooxanthellae is disrupted, and a global decline in reef corals. In the Arabian Gulf where water temperatures are naturally extreme with summer maxima at 35°C and above and winter minima at 18°C and below, seawater temperature anomalies are repeatedly recorded in the summer. While Arabian Gulf corals have naturally evolved to survive at temperatures that would cause bleaching and mortality to most corals elsewhere, an increasing number of mortality events have been recorded in the Gulf (Qatar, Saudi Arabia, and the UAE) in the last decades, resulting in a substantial loss of biodiversity and coral cover, mostly in inshore environments. Efforts are being deployed locally to conserve remaining habitats and attempt the restoration of lost habitats, but to be successful, efforts need to incorporate regional species-specific traits such as the susceptibility and resistance to future bleaching. We here assess the tolerance and sensitivity of three ecologically important species from the Arabian Gulf, Acropora downingi, Porites lutea, and Dipsastraea pallida, sampled in Qatari offshore reefs in the mid-winter, by exposing them to heat stress in enclosed aquaria. Colonies were assigned to control aquaria maintained at 25°C, aquaria to be raised to 30°C, or aquaria to be raised to 36°C. After an acclimatization period, the 30°C and the 35°C aquaria were raised to their target temperature at a maximum rate of 1°C per day. During the warming period and for another three weeks, we monitored the photosynthetic activity of their symbiotic zooxanthellae twice a week with a diving-PAM fluorometer while checking for signs of bleaching. We found that the photosynthetic activity was not affected in any of the three species when the temperature was raised from 25°C to 30°C. At 34°C, the photosynthetic activity in A. downingi started declining. Once the temperature reached the 35°C target, all A. downingi colonies bleached, expelling their zooxanthellae, and died three days later. The photosynthetic activity in P. lutea and D. pallida started declining once the temperature reached 35°C and continued declining for an additional three weeks, after which P. lutea died and D. pallida recovered. The high tolerance of P. lutea and especially of D. pallida is promising for the survival of the two reef-builders in coming years, despite increasing seawater temperatures caused by climate change. However, the branching Acropora coral is not expected to respond well to any further increase of temperature, as reflected in its major regional decline in the past decades. Due to its high sensitivity, Acropora might also not be a good candidate in coral restoration projects, as it showed a high sensitivity to bleaching and the inability to survive bleaching events. However, aquarium conditions not being able to fully reflect natural conditions on the reef, further work would need to be conducted directly on the reef to determine whether other factors might be involved in assisting resistance to bleaching, survival under bleaching conditions, or recovery following bleaching. In any case, P. lutea and D. pallida would be excellent candidates in coral restoration projects, having showed a lower sensitivity to bleaching and the ability to survive for several weeks under thermal stress, therefore showing potential for a long-term survival even under warming conditions.
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Developing an ecofriendly approach to reduce the use of biocides for preventing Microbial Induced Corrosion
By Saad RasoolSulfate Reducing Bacteria (SRB) cause significant damage to marine oil pipelines necessitating the use of biocides for reducing the Microbial Induced Corrosion (MIC) and potential for great environmental harm. Currently, oil companies pump frequent batches of biocides to these under water pipelines without proper quantification of the bacterial population. This is primarily because the existing method for quantifying the bacterial population in a sample is not very effecient, as it can take up to 2 weeks to obtain the results. Our team has focused on developing an eco-friendly approach to limit the use of these biocides, which are used for targeting the SRB. SRB require high salt and low oxygen so first we genetically engineered a strain of bacteria that would report the osmolarity in oil pipelines, thus act as a biosensor for salt concentrations. The ratio of salinity in the seawater flowing in versus the seawater flowing out of the well will be used to estimate SRB populations in the pipelines, thus limiting the amount of biocides added in times of high Microbial counts.
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CFD Analysis of Falling Film Wettability in MED Desalination plants
Authors: Furqan Tahir, Abdelnasser Mabrouk and Muammer KocIn Gulf Cooperation Council (GCC) countries, 56% of the market is captured by thermal based desalination (both MED and MSF), while in Qatar 91% is based on thermal desalination. Among the thermal desalination technologies, Multi Effect Desalination (MED) operates at lower specific power consumption and is considered more energy-efficient than the Multistage Flash (MSF) distillation. The lower energy consumption of MED plants is due to high overall heat transfer coefficient and low pumping power. The most common problem in MED evaporators is fouling of tubes, which reduces heat transfer and performance. Horizontal falling film evaporators are the most common evaporator type used in MED; in which liquid film is maintained outside the tube and part of it evaporates producing vapors. Improperly maintained liquid film leads to fouling i.e. formation of salts on the surface of tubes, which affects heat transfer properties of the surface. So in order to minimize fouling, tubes should be completely wet; especially column based on second row in triangular pitch configuration and bottom row tubes, which receive lesser mass flux. Wettability study of falling film evaporator in 3-D domain is carried out using commercial CFD tool i.e. Ansys fluent v18.0. A column of three tubes having OD 19.05 mm, vertical pitch of 24.7 mm and 20 mm section is considered in this study. Brine inlet has an opening of 1 mm × 1 mm and mass flux (Wetting rate Γ) is varied from 0.03 kg/m-s to 0.2 kg/m-s. This mass flux variation include all flow regimes namely droplet, column and sheet modes. For multiphase flow, volume of fluid (VOF) model is selected, as this model is used where two phases are separated in the flow regime. Wall adhesion model is incorporated for film and tube contact. Conservation of mass, momentum and energy equations were solved in a transient manner via SIMPLE algorithm for pressure-velocity coupling. All equations were discretized in 2nd order and residual for convergence criteria was set to 10-6 for better accuracy. The time step was taken 5 × 10-6 s, to ensure that the global courant number is below 0.25 and iterations for each time step were 40. Initially mesh dependency check was carried out and then the model was validated against available data in the literature. CFD results show that at lower mass flux i.e. 0.03 kg/m-s, tubes are not completely wet and there are dry patches, which are more susceptible to fouling. As the mass flux is increased flow regime changes from droplet to column and then to sheet mode. Increasing mass flux diminishes dry patches problem but also at higher mass flux, film is detached from tube surface causing lower portion of tube to remain dry. There is no fixed critical value for flow regime transformation as it depends on many factors like tube Outer Diameter (O.D.), tube pitch, nozzle type, nozzle diameter and solution properties etc. Moreover, the effect of surface roughness was also taken into consideration and it was concluded that more roughness results in better film stability and enhanced wettability.
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Shallow Aquifer upper ∼120 m Rocks of Qatar: Depositional and Diagenetic Controls on Water Storage Capacity and Hydraulic Conductivity
More LessCarbonates and evaporites of Paleogene-age form the shallow-aquifer rocks that mantle most of Qatar, including the Paleocene and Lower Eocene Umm er Radhuma, and the Middle Eocene Rus and Dammam Formations. Nearly complete 10-cm-diameter rock cores have been recovered from boreholes in central and northern Qatar to depths of greater than 120 m. A 40-m section of exposed Rus and Dammam Formation from a cave in central Qatar (Misfer Cave) was also described. Assessment of aquifer quality in these rocks was undertaken through core and thin-section description, quantitative mineralogical determination (X-ray diffraction), as well as core-plug porosity, permeability, and pore-throat (mercury-injection capillary pressure) measurements.
Our work shows that the rocks from central Qatar can be separated into four depositional intervals: 1) m-scale fining-upward cycles of fossiliferous open-marine deposits with clay-rich caps (Umm er Radhuma), 2) fine-grained stromatolite-bearing, restricted shallow-marine deposits (uppermost Umm er Radhuma), 3) m-scale bedded marginal-marine gypsum deposits intercalated with thin shallow marine carbonate and clay deposits and capped by rooted and microcodium-bearing surfaces (Rus Formation), and 4) open-marine carbonates overprinted by karst processes (Dammam). Aquifer storage capacity and hydraulic conductivity are mostly a function of diagenetic features, and in spite of the lack of any evidence of significant burial, the diagenesis of these rocks is complex. The Umm er Radhuma and the Rus carbonates are almost completely dolomitized, whereas the Dammam is only partially dolomitized, with the amount of dolomitization varying both laterally and vertically. Best aquifer quality in central Qatar, based both on core plug data and well spinner tests, can be found in coarsely-dolomitized intervals that lack clay (lower Umm er Radhuma). Finer and clay-bearing dolomitized rocks have storage but lower hydraulic conductivity (upper Umm er Radhuma). Both gypsum-rich rocks and depositional limestones (which are generally mud-bearing) have lower porosity and permeability (Rus and Dammam). In central Qatar the effect of karst overprinting is variable, generally leading to lower matrix porosity and permeability due to clay translocation from above, but large vugs are also observed at exposure surfaces.
The borehole in northern Qatar was located within a karst collapse feature (doline) that is characterized by internal drainage. Based on satellite images, the collapse feature, likely reflecting the presence of deeper karst is approximately 1 km in width. Sediment tentatively interpreted as a cave deposit, and composed mainly of dolomite silt, has been observed in this core at depths of greater than 60 m below the surface. This fine-grained material intercalates with courser breccias that are interpreted as collapsed country rock. The impact of karstification on country rock matrix properties (porosity and permeability) is still to be determined. Whereas the rocks from northern Qatar are still under investigation, they are distinct from the central Qatar equivalents in that they lack any bedded evaporites. This leads to the prediction that the shallow aquifer in northern Qatar will be less compartmentalized than in central Qatar. The elemental makeup of waters from different stratigraphic intervals in both boreholes are being compared to help understand how the central and north shallow Qatar aquifers contrast.
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Developing a Framework for a Dynamic Modeling Tool to Support RiskBased Decision Making in the Petrochemical Industry
Authors: Rym Kanes, Clementina Ramirez-Marengo, Ali Sheharyar, Othmane Bouhali, Luc Vechot and Emilio AlvarezProcess Safety in the oil and gas industry is managed through a robust process safety management system that involves the assessment of the risks associated with a facility, throughout its lifecycle. Typical approaches for risk assessment of an accident scenario includes: the identification of hazards, the estimation of the frequency, the analysis of possible consequences, and the evaluation of the risk against a company's tolerance criteria. While current quantitative risk assessment methods (e.g.: Layer of protection analysis (LOPA), Bow Tie analysis (BT), etc.) have brought significant improvements in the management of major hazards, they tend to provide static values of risk at a given time (snapshot at the time of the assessment). In reality however, risk levels tend to fluctuate throughout the lifecycle of a process, due to several time-variant risk factors, which include: equipment aging (which impacts their reliability), variations in the integrity and vulnerability of safety barriers, plant activities (e.g.: maintenance, shut-down), health and efficiency of the process safety management system, process safety incidents or near misses, etc. Thus, to that effect, risk is dynamic in nature and risk assessment approaches should allow for continuous updating of risk values over time. Over the last decade, the petrochemical industry has put significant efforts in developing process safety indicators (PSIs) to continuously measure the health and efficiency of process safety management systems. This has increased the sources of information that are used to assess risks in real-time. Hence, there is an opportunity to leverage PSIs along with equipment/safety barrier performance data to estimate the quantitative measure of risk levels in a process facility on a time-variant basis. ExxonMobil Research Qatar (EMRQ) partnered with the Mary Kay O'Connor Process Safety Center – Qatar (MKOPSC-Q) to attempt development of a tool that uses Bayesian Belief Networks (BN) to capture any potential increase of risk levels in real-time as a result of pre-identified risk factors and reliability data of equipment and safety barriers. The tool is referred to as PULSE, which stands for Process Unit Life Safety Evaluation, and is intended to be used to support existing decision making practices. The work involves a phased approach that first included the development of a methodology to establish the framework for the tool. Then, implementation and testing of the framework was attempted using BN algorithms. The most recent phase involves application of the tool to maintenance and inspection planning. In this context, the work presented here demonstrates the feasibility of using PULSE to quantify changes in risk level for a process unit based on a case study from literature. Furthermore, the different aspects of PULSE development are described. These aspects include: translation of the Bow Tie into a BN, modification of the BN to include reliability data, and insertion of equipment failure incidents into the BN to perform dynamic modeling. The outcomes of the dynamic modeling with real time insertion of equipment failure evidence are discussed. Also, the application of dynamic modeling to support risk-based decision making with regards to inspection and maintenance planning is included.
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NASICON based Na4MnV PO4 3/MWCNTs Cathode Materials for Naion Batteries with Improved Electrochemical Performance
Lithium ion batteries (LIBs) have completely captured the portable electronics and electric vehicle market due to their tempting performance. However, due to limited reserves of lithium, the price for lithium is constantly increasing which necessitates to trace out some decent alternative to lithium ion batteries. In this regard, sodium ion batteries are considered one of the best substitutes for lithium ion batteries due to inherited properties of sodium metal like abundance of resources across the globe, ease of availability, economy and environmentally friendly nature. Moreover, sodium ion batteries follow the similar electrochemical principles as the lithium ion batteries which indicates that knowledge and understanding of principles of lithium ion batteries can be utilized for the development of smart sodium ion batteries. In this work NASICON (Na+ super ionic conductor) based Na4MnV (PO4) 3 was synthesized using the sol - gel technique. As prepared Na4MnV (PO4)3 demonstrates an active redox couple at around 3.6 V and 3.2 V during oxidation and reduction process respectively. The pristine Na4MnV(PO4)3 shows good initial discharge capacity ∼ 138 mAh g-1 at 0.05C. However, it shows rapid discharge capacity fading with increasing discharge rate (138 mAh/g at 0.05C and 15 mAh/g at 2C) and poor cycling performance (68.0% of the initial capacity was retained after 40 cycles) with increasing discharge rate. To improve the electrochemical performance of the developed material, Na4MnV (PO4)3/MWCNTS (MWCNTs = 1 & 3wt. %) were synthesized. The initial discharge capacity of these materials at 0.05C was found to be similar to pristine Na4MnV(PO4)3, however, the addition of MWCNTs has resulted in significant improvement in the discharge capacity at high c-rate which can be mainly attributed to the enhanced electronic conductivity of the pristine material. Apart from higher capacity at high c-rates, the addition of MWCNTs has also improved the cyclability of the pristine Na4MnV(PO4)3. A capacity retention of 99.0 % and 98.00% of the initial discharge capacity after 40 cycles is noticed for Na4MnV(PO4)3/1wt.%MWCNTs and Na4MnV(PO4)3/3wt.%MWCNTs respectively. The improved performance of Na4MnV (PO4) 3/MWCNTs cathode materails make them attractive for energystorage applications.
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Gas Driven Fracture during Gas Production using HeleShaw Cell
Authors: Riyadh Al-Raoush, Zaher Jarrar, Khalid Alshibli and Jongwon JungMethane hydrate is considered a potential energy source, with worldwide reserves on the order of 500–10,000 Gt of carbon. The production of Methane from hydratebearing sediments requires hydrate dissociation for releasing mobile methane gas in sediments prior to gas production operation. Existence of even a small fraction of fines can greatly decrease the permeability of sandy sediments, which will affect the gas recovery process. Fines can migrate through or clog the pores of sandy sediments depending on geometric constraints such as the ratio of the size of the pore throat to the size of the fine particle. In multiphase flow, clogging of fines at the pores causes a change in pressure gradient which affects the flow of gas through the pores and might induce gas driven fracture. In the literature, there is a major knowledge gap that needs to be resolved to develop technical and economically viable methane production strategies from gas hydrate reservoirs. A comprehensive understanding of the underlying physical processes such as fines migration, clogging, and gas-driven fracture during gas production in hydrate bearing sediments is needed. Effects of fines migration and clogging on gas flow path and gas driven fracture were studied for Carbon Dioxide (CO2). This was achieved by conducting multiphase flow experiments on brine saturated sand-kaolinite mixtures using 2D Hele-Shaw cell; a common analogous model that has been used to investigate particle displacement process in sediments and has the unique advantage in allowing real-time visualization. The cell consists of two transparent acrylic sheets that are separated by a small gap. The gap between the two sheets is maintained using filter sheets that have a thickness of 1/16 in. (1.6 mm) at the boundaries. Fluids flow radially between the sheets through a port in the middle of the bottom sheet. Multiphase flow experiments are conducted on samples of brine saturated uniform F75 sand mixed with kaolinite at different percentages by weight (0% to 20%). Pressure volume actuator (flow pump) is used to inject brine into the sample for saturation. Following saturation, CO2 is applied to the cell at a constant pressure (2 kPa, 5 kPa, and 10 kPa). Variation of gas pressure is monitored using a pressure sensor that is attached near the port of the cell. The injection processes are recorder using a high resolution digital camera mounted above the cell. Gas pressure was found to increase with increasing fines content, which indicates the clogging of pores by kaolinite particles. Particle image velocimetry (PIV) analysis was conducted using PIVLAB code on MatLab. Velocity vector field and density plots of velocity field were generated to track particles displacements. Particles near the fracture tip were moving at the highest velocity. The results showed three different regimes of gas flow through sediments. For low concentration of fines, the gas percolates through the pores with no major host particles displacement. For a high concentration of fines, major particle displacement occurs and gas driven fractures are created. Gas solely flows through those generated cracks with no observed percolation. Finally, a combination of the two regimes takes place for intermediate fines content.
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Groundwater pollution by petroleumderived contaminants in coastal semiarid environment
More LessA common source of contamination of soil and groundwater in arid and (semi)-arid coastal regions are accidental spills of petroleum products, such as crude oil, gasoline, and diesel fuel. Groundwater pollution by petroleum hydrocarbons is a serious pollution problem that poses hazards to water resources and living organisms including humans. After release to the sub surface, hydrocarbons move downward through the aerobic vadose zone under the force of gravity. Eventually, they reach the groundwater table, where oil overlay promotes the development of anaerobic conditions. The oil phase that occurs as floating product on the water table and as residuum on soil grains provides a continued source supplying hydrocarbons to the groundwater. Accumulations of residual hydrocarbons at or near the water table may undergo smearing due to variations in water table elevation driven by, for example, seasonal changes in recharge and discharge or by tidal forcing in coastal environments. In subsurface environments contaminated by petroleum products, the geochemical conditions near the water table, in particular, the oxygen availability, moisture content, salinity, pH, nutrient concentrations and temperature, are important determinants of biogeochemical processes. Among these variables, the interplay of moisture content, oxygen availability and temperature are critical for understanding the biodegradation of petroleum hydrocarbons in arid and (semi)-arid coastal soil environments. In addition, the fate and transport of hydrocarbons in groundwater also depend on the redox conditions, soil mineralogy and microbial community structure, as well as the availability of suitable electron acceptors and nutrients. We hypothesize that the transition zone between the vadose zone and the groundwater system represents a hot spot for the degradation of petroleum hydrocarbons. This transition zone, however, is a dynamic biogeochemical environment, whose functioning is closely linked to the amplitude and frequency of water table fluctuations. We propose to determine the role of water table fluctuations on the coupled hydrological and biogeochemical processes that affect the degradation and partitioning of petroleum hydrocarbons, under conditions relevant to aquifers. Coastal areas in this regard can function as zones of contaminant mass transfers between aquifers and surface water bodies, but also as excellent spots of in situ bioremediation of contaminated soil and groundwater thanks to coupled hydrological and biogeochemical processes. The main objectives of this project are to: 1) quantify the level of sorption and biodegradation of multi-component hydrocarbons in soil and groundwater; 2) quantify the rates of hydrocarbon biodegradation under oscillating aerobic and sulfate reducing conditions in groundwater contaminated with petroleum hydrocarbons; 3) determine the oxygen dynamics in the vadose zone and groundwater affected by hydrocarbon dispersion under variable water table fluctuation regimes; 4) assess the rates and mechanisms of biogeochemical reactions regulating groundwater nutrient turnover during hydrocarbon spill and its movement under conditions of groundwater table fluctuations; and 5) develop a reactive transport model for groundwater pollution by petroleum hydrocarbons. In this project, we combine the acquisition of integrated physical, chemical and microbial data using uniquely designed process-oriented experimental approaches. The results of this project will significantly add to the quantitative knowledge on the effects of water table fluctuations on the release and degradation of petroleum-derived hydrocarbon contaminants in soil environments that experience both arid conditions and tidally-driven water table fluctuations. The expected results of the research will inform groundwater management and protection in arid and (semi)-arid coastal environments. To quantify the level of sorption and biodegradation of petroleum hydrocarbons in subsurface soils and groundwater (Objective 1), we conducted a series of controlled-laboratory batch experiments under variable salinity, temperature and water chemistry conditions. The soil samples were collected from the eastern coast of Qatar which is close to the North Gas and Al-Shaheen Oil Fields. The initial physical characterization of soil samples showed sand classification with the texture class of sabkhas soil. The results of soil-phase chemical characterization suggested that the dominant minerals of the soil are calcite, dolomite and gypsum and the concentrations of chloride and sodium were found to be high with a chloride-to-sodium ratio of ∼1.6.We used volatile benzene and naphthalene hydrocarbons to determine the sorption and biodegradation rates. The results of sorption experiments showed that naphthalene was adsorbed to the soil more than benzene where the initial aqueous concentrations of benzene and naphthalene were reduced at equilibrium due to sorption by approximately 10% and 75%, respectively. This difference was attributed to the organic carbon-water partitioning coefficient which is higher for naphthalene. We developed a sorption kinetics model to define the sorption isotherm of benzene and naphthalene hydrocarbons for the specific coastal soil collected from Qatar site. The model assumes the two sites sorption to the soil, one site in local equilibrium and the other site on first-order kinetic sorption, and the best fits were found for the Langmuir sorption isotherm type for the used hydrocarbons and soil in this project. In this presentation, we present the results of sorption and biodegradation batch experiments as well as the design of a unique dynamic soil column experiment to understand the dynamic responses of the fate, transport and degradation of hydrocarbons and the soil biogeochemical processes to the relatively abrupt changes in hydrogeochemical and climatic conditions.
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Fines migration and clogging behavior in methane hydratebearing sediments
Authors: Jongwon Jung, Shuang Cao, Riyadh Al-Raoush and Khalid AlshibliThe structure of natural hydrate-bearing sediments that exist offshore or onshore is a combination of coarse-grained sediments and fine-grained particles. During gas production from hydrate-bearing sediments, fine particles may migrate with the flowing fluids within pore space and cause clogging of the pore space of the porous media. Therefore, fine particles play a significant role during methane production from hydrate-bearing sediments as it impact the overall sediment formation performance and production efficiency. The migration of fine particles and its impact on clogging have been investigated in a single-phase flow, but it has not been clearly understood in a multi-phase flow. This research focuses on the study of fines migration and clogging behavior during single and multi-phase flow which can be implicated in gas production from hydrates bearing sediments. Microfluidic pore models that mimic porous media with different pore throat sizes were fabricated and utilized to study fines migration and clogging behavior in porous media. Artificial particles and natural fine particles were selected to represent fine particles. The impact of flow rate, pore-fluid types, particle concentration, and pore-throat to fine particle size ratio was investigated. Fine particles used in this research include polystyrene latex particles, silica, and kaolinite. Pore-fluids used in this study include deionized (DI) water, and sodium chloride (NaCl) brine (2M concentration). The particle concentrations covered from 0.1% to 10%. And the pore-throat widths were fabricated from 40 μm to 100 μm. Single-phase flow experiments were conducted to show that the concentration of fine particles required to form clogging in pores increased as flow rate decreased. The results obtained using polystyrene latex particles provide the insight at a relatively higher flow rate (50 μl/min) than literature studies that fine particles with 2% concentration can migrate in the pore throat without bridge or clogging at the various pore throat and fine particle size ratios (o/d = 2.6∼36.4). Furthermore, silica presents higher critical clogging concentration (0.5% in brine) compared with kaolinite (0.2% in brine) when the pore-throat width equal to 60 μm due to the larger pore throat and fine particle size ratio. On the other hand, the findings show that clogging easily occurred at a lower pore-throat to fine particle size ratio even with a few number of fine particles. In addition, pore-fluid type directly influences the tendency of fine's to form clusters which in turn impacts the clogging behavior. For instance, silica fines clogging easier occurs in brine solution compare within deionized water due to larger cluster size in brine, while kaolinite shows an opposite result which means the kaolinite has higher clogging possibility in deionized water compared within brine solution. On the other hand, findings of multi-phase flow experiments show that fine particles accumulate along the liquid-gas interface and migrate together, which in turn cause bridging or clogging to occur easily in pores. These observations imply that a multi-phase flow during gas production could easily form clogging in pores, in which the flow permeability of porous media decreases even though clogging has not occurred in the same conditions with a single-phase flow. Thus, the permeability of porous media in engineering applications should be estimated by considering relatively easy clogging in pores in a multiphase flow compared to a single-phase flow. Findings of this research show the vital impact of pore-fluids and fluid-fluid interphase on fine particles migration and clogging in porous media. It provides a better understanding of the fines migration and clogging mechanisms. In addition, the results indicate the need to understand the types of fines and fluids in reservoir before evaluating if there will be a clogging potential during gas production from hydrates bearing sediments.
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Invitro conservation of some rare and threatened desert plants in Qatar
Authors: Talaat Ahmed and Mohammed AlsafranBackground A range of natural factors, invasive animals and human activity have been severely affecting stability of the ecosystem, resulting in the annihilation of plants habitats and so plant endangerment or even extinction. In Qatar, urgent action needs to be taken to stop decline of desert plant species as well as an effective strategy should be applied to reverse and save these wild endangered plants. Otherwise, they will be faced with the danger of their extinction in near future. Therefore, it is very important to have knowledge of protection measures, such as replanting and propagating through tissue culture technology, to protect the biodiversity in Qatar. Plant in-vitro culture systems have been used as an alternative approach to propagate and conserve a large number of rare and endangered plant species that show difficulties to be propagated using conventional methods of propagation. It was reported that standard culture environment could be effectively employed for short-term in-vitro conservation of different plant germplasm, through increasing intervals between subcultures especially in slow growing plant species. Objectives In the current study, conservation of rare and endangered desert plants using in-vitro culture were developed. Generally, these plants are not easy to be propagated by classical horticultural methods. Different techniques including micro-propagation, in vitro seed germination, and regeneration from callus were applied to propagate and conserve three endangered plant species in Qatar; Leptadenia pyrotechnica, Glossonema varians and Prosopis cineraria. Methods Collection of endangered plant species Location of the endangered plant species were identified and the plant parts- seeds, stem, shoots, roots, nodal cuttings or whole plant- depending on its type and availability, were collected. Surface sterilization of the collected material The plant materials were washed with tap water to remove dust and debris, then were soaked in 70% ethanol for 1–2 min, then were treated with sodium hypochlorite or Clorox for 10–20 min followed by rinsing 3–5 times with sterilized distilled water under aseptic conditions. In-vitro plants formation Organ culture using nodal sections of the plants were cultured on hormone-free MS medium (0.5X) for in vitro plants formation. For seeds were cultured on medium containing gibberellic acid (GA3) for efficient seeds germination. In this way, in vitro plants were established and multiplied to produce large number of healthy clones. In case seeds or nodal cuttings are not available, other plant parts like leaf or root were used as explants to initiate callus tissues. Results Seeds of Leptadenia pyrotechnica were collected, surface sterilized and germinated under aseptic condition using 0.5X MS media. In-vitro employing tissue culture via callus and shoot induction using different growth regulators was explored. Seedlings from in-vitro germination of the seed were used as explants. The results revealed that the highest callus production was obtained using 2.0 mg/L BAP. In addition, 0.5 mg/L and 2.0 mg/L NAA were good for callus initiation, compared to other hormones. Seedlings of Glossonema varians were collected were used as an explant for callus induction. Several plant growth regulator were used to initiate callus including 2, 4, D, NAA and BAP and their combinations. The results showed that the best plant growth regulators to induce callus were 1.5 mg/l IBA and 2 mg/l BAP. Prosopis cineraria, is a famous tree in Qatar. It is not easy to be propagated by classical horticultural methods. Seed dormancy was broken by scratching via sand paper. Several plant growth regulator were used to initiate callus including 2, 4, D, NAA and BAP and their combinations. The results showed that the best plant growth regulators to induce callus were both 2.0 mg/l 2, 4, D and 1.5 mg/l IBA. The obtained callus will be treated to regenerate new plantlets. Adventitious shoots and roots formation will be induced and a large number of in vitro plants will be produced. The in-vitro grown clones will be hardened (acclimatized) for greenhouse and later field conditions. The in-vitro plants will be removed from the cultures; medium will be removed by washing with running water and sown in pots. The pots will be covered with plastic sheets to keep high humidity and gradual removal of the plastic will harden the plants for greenhouse.Conclusions Recently, in-vitro culture technique of desert plants has received importance because it can be used for the fast propagation and ex situ conservation of endangered plants. The success of micro-propagation and in vitro conservation of the selected endangered plants depends on the best choice of the explants, the efficiency of the sterilization method and correct plant growth regulator. The best in-vitro conservation of the selected plant species is in MS media with the following plant hormones 2, 4, D, NAA. IBA and BAP.
Acknowledgements «This study was made possible by UREP grant # UREP19-209-1-037 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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CuI and CuSCN as Hole Transport Materials for Perovskite Solar Cells
CuI and CuSCN as Hole Transport Materials for Perovskite Solar Cells Vinod E. Madhavan1*, Ahmer Ali Bozdar Baloch1, Afsal Manekkathodi1, Dhanasekaran Thirunvukkaarasu1, I. Zimmermann2, C. Roldán- Carmona2, G. Grancini2, M. Buffiere1, Mohammad Khaja Nazeeruddin2, A. Belaidi1 and Nouar Tabet1 1 Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P. O. Box 5825, Doha, Qatar 2 Group for Molecular Engineering of Functional Materials, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1951 Sion, Switzerland *[email protected]. ABSTRACT: Perovskite based solar cell is an important area of research for solar energy harvesting and for green energy revolution. The materials used for a thin film solar cell are considerably less with respect to the prevailing silicon based solar cells. There is an interest in copper based inorganic materials, especially copper iodide (CuI) and copper thiocyanate (CuSCN) as hole transport materials (HTMs) in perovskite solar cells (PSCs) for efficient, inexpensive and stable energy harvesting. Copper based films exhibit higher conductivity and wider-band-gap. The existing organic HTMs are expensive and have low hole mobility. The reported high power conversion efficiency (PCE) of CuI and CuSCN based perovskite solar cells are 6% and 20.3% respectively [Christians et al. J. Am. Chem. Soc., 2014, N Arora et al. Science 2017]. The perovskite solar cells based on inorganic CuI and CuSCN can be more stable and cost-effective with respect to spiro-OMeTAD HTM. We present our work on mixed perovskite in the form of (FAPbI3)0.85(MAPbBr3)0.15 in combination with CuI and CuSCN HTMs that lead to efficiencies 5.16% and 15.43% respectively in an n-i-p architecture under full sun illumination. The CuI based device displayed a short-circuit current density (Jsc) of 8.98 mA/cm2, Voc of 898.57 mV and fill factor (FF) of 0.64. Under similar conditions, the device with CuSCN, showed a significant increase in the Jsc (8.95 mA/cm2 to 20.86 mA/cm2) and Voc (from 898.57 mV to 1060 mV) (Figure1). A reference cell with standard spiro-OMeTAD HTM showed a PCE of 19.65% (with Voc of 1180 mV and Jsc of 22.70 mA/cm2). The high Jsc when using CuSCN with respect to CuI is mainly due to the effective charge extraction between the perovskite and CuSCN. However there is a strong quenching in the photoluminescence measurements in both CuI and CuSCN cases, which suggests that excellent hole injection is taking place from the perovskite active layer into the CuI and CuSCN hole transport materials (Figure 2). It is worth noting that CuI based perovskite devices showed a PCE of 6% with excellent photocurrent stability and 2 orders higher electrical conductivity that lead to higher fill factors [Christians et al. J. Am. Chem. Soc., 2014]. Impedance spectroscopy measurements revealed high recombination rate in CuI devices [Huangfu et al, Applied Surface Science 2015]. This could explain the low Voc and Jsc despite the quenching of the photoluminescence spectrum in the presence of CuI and CuSCN. Further studies are in progress in-order to find out the origin of the recombination and how to remediate them. Various device structure models (p-i-n and n-i-p geometry) with copper based HTMs are simulated with SCAPS software to find out the efficient structures with minimum losses. The results shows that the CuSCN based cells are more promising and can be used to prepare high efficiency perovskite solar cells. References J.A. Christians, R.CM. Fung, P.V. Kamat, J. Am. Chem. Soc. 2014, 136, 2, 758–764 pp. N. Arora, M. I. Dar, A. Hinderhofer, N. Pellet, F. Schreiber, S.M. Zakeeruddin, M. Grätzel, Science 2017,10.1126/science.aam5655. M. Huangfu, Y. Shen, G. Zhu, K. Xu and M. Cao*,F. Gu and L. Wang, Appl. Surf. Sci. 2015, 357-B, 2234–2240pp.
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Distribution Identification Isolation and Culturing of Cyanobacteria Found in Qatari Microbial Mats and its Applicability for Treatment of Industrial Wastewater
More LessA significant global environmental opportunity of today is finding beneficial reuse for industrial and domestic wastewater through appropriate treatment, redistribution and application. Although industrial wastewater may present various challenges in terms of exotic or hard to treat constituents, finding effective and efficient treatment options and subsequent reuse opportunities will be beneficial for many facets of the environment, especially in regions of the world where water scarcity is an issue. Numerous remediation methods have been developed to purify wastewater. Most of these are physiochemical in nature, which are often not effective to implement on a large scale and can be expensive. This research explores an environmentally natural approach using biological processes (microbial activity) to achieve the degradation of petroleum hydrocarbons. The objective of this study was to study microbes native to Qatar, in particular those found within microbial mats that are found in various areas around the country. The steps taken were to first estimate the area of microbial mats using GIS, identify the microbial species within these regionally specific mats, isolate and culture cyanobacteria from these mats and explore the applicability of using these organisms for treatment of industrial wastewater.
Microbial mat samples were collected from three geographical areas around Qatar, namely Ras Abrouq, Al Zubara and Khor Al Adaid. The collected microbial mats were firstly enriched in cultured medium. Different strains of cyanobacteria were isolated from these enriched mats and were cultured using solid media ASN-III and MN. Single strains of cyanobacteria were then sub cultured in BG-II liquid medium and were used to test the biodegradability of a test set of hydrocarbons (benzene, toluene and hexadecane). The optical densities of the cyanobacteria were measured using a spectrophotometer and the rate of biodegradation of the hydrocarbons were found using a Gas Chromatography Mass Spectrophotometer (GCMS).
Results show that most of the microbial mats identified in Qatar are found on the Dukhan coastline area. Another important area of mats is found at Khor Al Adaid (Inland Sea) located in the southeastern portion of the state. Different species of cyanobacteria were identified from these mats. The most common species identified from mats at Al Zubara were Oscillatoria, Phormidium, Microcolous, Lyngbya, and Spirulina. Those from Khor Al Adaid were Plectonema, Synechococcus, Phormeduim, Lyugbya, Oscillatoria, and Trichodesmium. Those from Ras Abrouq consisted mostly of Microcolous, Lyngbya, Pseudanabena, Oscillatoria, Phormidium, Spirulina, Gloeocapsa, and Aphanothecechroococcus.
Two species of the cyanobacteria, Oscillatoria and unicellular Cyanococcus, were successfully cultured and sub cultured in BG-II medium and used for biodegradation studies with hydrocarbons. Initial results suggest these species are capable of degrading hydrocarbons, but further studies are required to determine to what extent.
For future research, the duration of incubation of microbes with the chemicals of interest for degradation could be increased to help confirm capability. Furthermore, mixtures of different species of cyanobacteria could be used to understand if populations play a role in achieving effective biodegradation of hydrocarbons. This work is also being expanded to explore other microbes found around Qatar and testing their applicability to be effective “biodegraders”. All this research may be beneficial with our larger goal of finding more effective, efficient and environmentally natural approaches to treating industrial wastewater.
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Yeast Volatile Organic Compounds Inhibit Ochratoxin Biosynthesis By Aspergillus Carbonarius and a Ochraceus
Authors: Zahoor Ul Hassan, Maria Farbo, Pietro Urgeghe, Angela Marcello, Samir Jaoua and Quirico MigheliOchratoxin A (OTA) has hepatotoxic, teratogenic, nephrotoxic and carcinogenic effect in mammals and it is classified as a group 2B carcinogen by the World Health Organization. The European Union has set the maximum OTA level at 2 mg/kg in wine, grape juice, and other grape products, and at 3 mg/kg for all products derived from cereal, including cereal products and cereal grains for human consumption. Some species of Aspergillus are the main source of OTA in warm and tropical regions, and in particular Aspergillus carbonarius (Bainier) Thom is considered one of the most relevant OTA producers in food and feed. Inhibiting the growth of OTA-producing fungi on sensitive commodities is by far the most reliable method to prevent OTA contamination of food and feed. Aim of this study was to evaluate the biocontrol ability of selected yeast strains against OTA producing Aspergillus carbonarius and Aspergillus ochraceus. In a previous report, two non-fermenting (Cyberlindnera jadinii 273 and Candida friedrichii 778) and two low-fermenting (Candida intermedia 235 and Lachancea thermotolerans 751) yeast strains have shown a significant antagonistic behaviour against a virulent strain of A. carbonarius on grape berries as well as in in vitro experiments, while the filtrated and autoclaved culture broth of the yeast strains had no significant effect on pathogen growth.This biological effect was at least partly due to the release of volatile organic compounds (VOCs), since growth inhibition was observed without contact between yeast and Aspergillus spp.. Aspergillus colonies exposed to yeast VOCs did not sporulate, and were characterized by a white mycelium; the colony border was undefined, with elongated and scattered hyphae compared to unexposed control. Single hyphal tips and mycelium fragments were then transferred on PDA and after 5 days of growth at 25°C, typical dark sporulating colonies were evident, suggesting that the anti-sporulating effect is reversible. Aiming to further characterise the effect of VOCs produced by biocontrol yeast strains, we observed that, beside vegetative growth and sporulation, the volatile compounds significantly reduced the production of OTA by both A. carbonarius and A. ochraceus isolates. Exposure to yeast VOCs also affected gene expression in A. carbonarius, as confirmed by downregulation of polyketide synthase, non-ribosomal peptide synthase, and the regulatory genes laeA and veA. The main compound of yeast VOCs was 2-phenylethanol, as detected by Headspace-Solid Phase Microextraction-Gas Chromatography-Tandem Mass Spectrometry (HS-SPME-GC-MS) analysis. Yeast VOCs represent a promising tool for the containment of growth and development of mycotoxigenic fungi, and a valuable aid to guarantee food safety and quality. Further studies will aim at testing single purified VOCs in order to identify the most effective compounds responsible for the inhibition of fungal growth and OTA production by Aspergillus spp. in preventive food safety strategies.
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Evaluating the potential of using truck appointment systems to decrease reefer energy consumption at container terminals
More LessIn the recent decades there has been an unprecedented globalization of trade. One of the most important factors that made this possible is the containerization of the supply chain. As a consequence container terminals have become essential for todays globalized economy. The trend of containerization has further extended to the cold supply chain through the use of reefers (refrigerated containers), resulting in a tremendous increase in the trade of food and other perishable goods. In case of import dependent countries like Qatar the cold supply chain has become essential for food security. The number of reefers at container terminals has substantially grown and as a consequence their energy use. In average ports, the largest part of energy is consumed by crane operations and cooling of reefers. In case of ports that are dedicated to export/import of foods the cooling of reefers becomes the largest component of terminal energy consumption. This is especially the case in countries with extreme temperatures like Qatar. Although there has been a substantial amount of research dedicated to optimizing operational procedures of cranes at container terminals with a focus on minimizing energy use, similar approaches have not been explored in case of reefers and the related cold supply chain. In this work we focused on the potential of exploiting a terminal truck appointment system (TAS) to this goal. The main objective of the TAS is to minimize the waiting times at the port gates and to maximize the utilization of container yard equipment. It is important to note that previous research has shown that the information from the TAS can be used to optimize the crane operations. The majority of the existing research on TAS systems has been dedicated to evaluating the potential benefits that such systems can bring to a port in the sense of truck turn times. The concept of including reefer related information into a TAS adds a new dimension to the problem. This is due to the fact that the energy use of a reefer container is directly related to its dwelling time. The idea is to minimize the stay of reefers at the port. To be more precise the objective is to minimize the time since a reefer is unloaded to the port until a truck takes it out of the port. In practice this means that we wish to get the trucks that import the reefers to come to the port as soon as possible. This type of work adds a new type of objective where there is a higher priority related to trucks importing reefers. It is possible to develop a mixed integer program to assist in designing optimal methods for TAS related issues it is often not the best choice. The problem is that due to the high level of unpredictability in the movement of trucks inside and outside of the port the evaluation of a TAS system in this way is often not adequate. Due to this fact, the evaluation of such systems is frequently done using discrete event simulations (DES). In the existing literature the schedule for trucks is fixed, and further analysis is done to evaluate the effect of missed appointments and the percentage of «walk-in» trucks. The DES is only used for the truck arrivals to the port and related use of resources (Entrance Gate, Yard, Exit Gate, etc.). In the proposed research we extend the DES to also include dynamic appointment scheduling. To be more precise, we analyze how requests arrive and how appointments are given. This is important in the context of reefers since we want to give then higher priority, in the sense of leaving appointment slots open for truckers that transport them out of the port, which would otherwise be booked. The proposed DES is used to evaluate several strategies for appointments systems for both minimizing turn times of trucks and the dwelling times of containers. We show that some strategies can notably decrease the energy used for reefer cooling while maintaining short truck turn times.
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Performance of Antisoiling Coatings for Enhancement of PV Panel Performance in Doha
Authors: Maulid Mohamed Kivambe, Benjamin Figgis and Nouar TabetSevere temperature, humidity and dust characteristic of the desert region are major challenges in power generation efficiency of photovoltaic (PV) systems in the gulf region. Soiling can lead to daily average energy loss of up to 4% [1], necessitating frequent cleaning which adds to the cost. One of the solutions to the problem is to use anti-soil coatings, where hydrophilic or hydrophobic coatings with spectral characteristics suitable for PV applications are added to the outer layer of PV glass. However, it has been shown that the effectiveness of the coatings in reducing accumulation of dust in PV panels is dependent on climatic conditions [2-4]. Since coatings add to the cost of solar panels, it is imperative that the coatings are tested for suitability at the intended location or similar weather conditions prior to large scale application. In this work, anti-soil coatings on PV glass were tested outdoor in order to assess the effectiveness of the coatings as remedy for PV performance degradation upon exposure to environmental conditions of the Gulf region. Industrial anti-dust coatings on solar glass and uncoated solar glass; sample size ∼2.5 cm × 2.5 cm, were tested outdoor at Qatar Foundation's solar test facility (STF) in Doha. The coatings were hydrophobic (contact angle pre-exposure 83-90 degrees), while uncoated samples were hydrophilic (contact angle pre-exposure 34 -47 degrees). Measurements were taken pre-exposure (as received) and periodically upon exposure. The measurements were repeated after cleaning, which includes 3 day rain (Rain Clean), wash with free-running deionized (DI) water (DI-Clean), and wash with DI water with scrubbing (DI+S). The main test parameter of interest was radiant energy transmission properties. The impact of wind and humidity on energy transmission and the morphology and composition of the dust particles on samples were also analyzed. The following is a summary of the findings. Performance degradation due to dust is very high. Energy transmission loss of up to 37% was recorded during 13 weeks (week 8-week 20) of exposure, without dust storms (Fig. 1, 2).The advantage of coatings (over uncoated samples) is only marginal. Example, the average periodic energy transmission during week 8 –week 20 is < 1.5% higher for coated samples. Therefore, the tested anti-soil coatings seem not to offer significant remedy to performance degradation due to dust in Qatar. Patterned glass has better transmittance than plain glass, irrespective of coating type. Example, the average periodic energy transmission during week 8 –week 20 of exposure is ∼6% higher for patterned glass. The highest impact of dust in energy transmission is in the wave length range below 500 nm. This appears to be due to the high concentration of small (submicron) dust particles (see SEM images in Fig. 3).Cleaning recovers transmission to pre-exposure levels, except for shorter wavelengths (below 500 nm). This may suggest that smaller dust particles are difficult to remove. In-addition, presence of surface contaminants (non-dust-related) may require aggressive cleaning to remove.Dry wind appears to give a cleaning effect. Example, during W10 –W11, (Fig. 1) a period of fast winds (>2.5 m/s) and low humidity ( < 27%), energy transmission improved (instead of decreasing or remaining un-changed) for most of the samples. The morphology (Fig. 3) and compositions of dust on samples (Fig. 4) appear to be the constituents of the desert dust [5, 6]. However, dust particles exceptionally rich in Carbon (>30%), Iron (2%), Aluminium (>;4%) and Sulfur (>5%) have been observed. These may suggest existence of contribution from environmental activities such as transport and construction [7]. Dust particles with elevated amounts of Chlorine (3%) and Sodium (4%) have also been observed. These may indicate a contribution of salts from the sea [6, 7]. References [1] S. Semaoui, A. H. Arab, E. K. Boudjelthia, S. Bacha, and H. Zeraia, «Dust Effect on Optical Transmittance of Photovoltaic Module Glazing in a Desert Region,» Energy Procedia, vol. 74, pp. 1347-1357, 8// 2015. [2] Z. Abrams, P. Gonsalves, B. Brophy, and J. Posbic, «Field and Lab Verification of Hydrophobic Anti-Reflective and Anti-Soiling Coatings on Photovoltaic Glass,» Proceedings of the 29th EUPVSEC, pp. 2759-2764, 2014. [3] E. Klimm, T. Lorenz, and K. Weiss, «Can anti-soiling coating on solar glass influence the degree of performance loss over time of PV modules drastically?,» the 28th EUPVSEC, 2011. [4] E. Klimm, L. Ost, B. Spiegelhalter, and K. A. Weiss, «Tests of functional coatings on glass adapted to extreme - arid and maritime - climatic conditions for solar energy systems,» in Photovoltaic Specialist Conference (PVSC), 2015 IEEE 42nd, 2015, pp. 1-5. [5] T. Sarver, A. Al-Qaraghuli, and L. L. Kazmerski, «A comprehensive review of the impact of dust on the use of solar energy: History, investigations, results, literature, and mitigation approaches,» Renewable and Sustainable Energy Reviews, vol. 22, pp. 698-733, 6// 2013. [6] B. S. Yilbas, H. Ali, M. M. Khaled, N. Al-Aqeeli, N. Abu-Dheir, and K. K. Varanasi, «Influence of dust and mud on the optical, chemical, and mechanical properties of a pv protective glass,» Scientific Reports, vol. 5, p. 15833, 10/30/online 2015. [7] H. K. Elminir, A. E. Ghitas, R. H. Hamid, F. El-Hussainy, M. M. Beheary, and K. M. Abdel-Moneim, «Effect of dust on the transparent cover of solar collectors,» Energy Conversion and Management, vol. 47, pp. 3192-3203, 11// 2006.
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Experiment supported 2D COMSOL modeling of Fischer Tropsch Synthesis using Nonconventional media and Nonconventional catalyst
More LessFischer Tropsch Synthesis (FTS) is an exothermic chemical reaction in which synthesis gas (or ‘syngas’- a mixture of H2 and CO) is converted into hydrocarbons or value-added chemicals. In this process, a catalyst (typically cobalt based or Iron based) is used in a Fixed Bed (FB) or Slurry Bed (SB) reactor for the conversion process. Qatar hosts both the technologies in its world's largest Gas to Liquid (GTL) facilities (Shell Pearl GTL and Sasol Oryx GTL). Although both the technologies have been commercially implemented in a large scale, further process intensification by radial scale-up has been a challenging task due to certain process limitation associated with transport characteristics of both the beds. In particular, the FB technology has issues related to hotspot formation owing to exothermicity of the FTS process which is significantly better in its SB counterpart. Our efforts in the current study are invested to understand the FB performance when it is radially scaled-up to a higher reactor geometry, and to possibly mitigate the effect of hotspot formation. In particular, the objective of this work is to utilize the merits of nonconventional Supercritical Fluids FTS (SCF-FTS) to consolidate the benefits of both the beds (FB and SB) to address the challenges related to hotspot formation. For this, we have developed a multi-dimensional computational fluid dynamics (CFD) model in COMSOL® to facilitate a high-resolution understanding of both the SCF-FTS and conventional Gas Phase (GP)-FTS from the perspective of bed thermal management. As an extension to our previous modeling efforts in development of 1-D and 2-D FB-FTS model [1-2], we are currently involved in development of a multiscale 2D model to investigate the pore characteristics using both the modes of operation. Comprehensive experimental investigations were carried out at different operating conditions to support the modeling efforts. A conventional cobalt catalyst with inferior thermal conductivity was investigated in both GP-FTS and SCF-FTS. Later, a novel Micro-fibrous Entrapped Cobalt Catalyst (MFECC) with superior thermal conductivity was investigated in both GP-FTS and SCF-FTS. Conventional catalyst operated SCF-FTS conditions gave a very high value (0.90) than its GP-FTS. The MFECC catalytic bed on the other hand when operated in SCF-FTS conditions gave a slightly lower value (0.86), but six-fold % CO conversion than in GP-FTS. MFECC catalytic bed also exhibited higher C5+ selectivity & higher catalyst activity in SCF-FTS. In order to closely understand the intricate difference in thermal performance shown by the MFECC bed compared to conventional FB, we have performed a detailed CFD calculation. Results of the MFECC bed have shown to provide orders of magnitude improvement in bed thermal conductivity and proved its capability to control hotspot formation. In particular, the results of conventional FB at 20 bar and at a gas hourly space velocity of 5000 1/h in a reactor tube of 0.59 inch ID shows hotspot formation of about at the centerline. On the other hand, the temperature rise in MFECC bed for same operating condition was only. Further, a very recent outcome of this work enabled us to investigate the potential of scaling-up the radial geometry of the MFECC reactor to a 4” ID reactor to improve its throughput while maintaining temperature homogeneity in the reactor bed [2]. The proposed study is a part of a broader project involving both experimental and modeling studies, and is performed at multiple stages to enable mitigation of challenges related to reactor scale up, and runaway hotspot formation in a fixed bed FT reaction. References [1] M.M. Ghouri et al., Computers & Chemical Eng. 2016, 91, 38-48 [2] M.S. Challiwala et al., AIChE Journal, (Under Review)
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Density functional theory study of dry reforming of methane on nickel and nickel based bimetallic catalysts
More LessDry reforming of methane (DRM) reaction utilizes CO2, a major greenhouse gas to convert natural gas (mainly composed of methane) to synthesis gas, an important feedstock which could further be converted into valuable chemicals and cleaner fuel. This reaction presents a clear incentive in terms of its positive impact on the global environment and thus it has gained increasing attention in the last couple of decades. The superior catalytic activity of Nickel based catalysts and also their relatively lower costs make them the most promising catalyst for this reaction. However, these catalysts also deactivate rapidly owing to their high susceptibility to coke formation and filamentous carbon deposition. This severe catalyst deactivation is one of the major drawbacks that is obstructing the widespread commercialization of DRM. Several alternative catalysts have been explored for this reaction, including noble metals such as Rh and Ru. Even though these metals are found to be more reactive, as well as more resistant to carbon deposition, their high cost generally hinders their use [1]. One of the techniques that has been proposed to suppress the coke formation on the nickel surface is the substitution of single foreign transition metal atom which could modify the electronic structure [2]. In the current work, we present our exhaustive work on the solid state density functional theory (DFT) model results to study the wide network of elementary reactions comprising the DRM reaction on various facets of pure nickel catalyst, such as Ni(111) and Ni(100) surfaces. Calculations were performed using rev-PBE as exchange-correlation functional within the generalized gradient approximation (GGA) as implemented in the software VASP. Adsorption energies were calculated for all the DRM reaction intermediate species and then subsequently the activation barriers were calculated for all the elementary reactions in the DRM cycle. The catalytic activity of these pure nickel surfaces in terms of DRM reaction rate are then compared to the rates obtained on the single overlayer deposited nickel (X/Ni) surfaces where X is a transition metal such as Cu, Rh and Pd. Electronic structure analysis of various pure as well as overlayer modified surfaces is performed in terms of the d-band theory of catalysis. Our results indicate that the catalyst stability is greatly improved by a transition metal overlayer deposition on nickel surface. The carbon adsorption energy on a catalyst surface could be a good thermodynamic descriptor for estimating the coking tendency of this particular surface. One of the ways proposed in the literature to improve the coking resistance of a catalyst is to weaken the carbon adsorption energy. From a thermodynamic point of view, the decrease in the carbon adsorption energy on a catalyst surface would lower the surface coverage of carbon. This leads to a lower affinity for carbon deposition and an improvement of the coke reasistance of the catalyst. Our initial results indicate that the most stable adsorption energies of carbon on pure nickel surfaces are of the order of − 7.5 and − 8.96 eV respectively for the (111) AND (100) surfaces. Whereas, for the copper modified (111) and (100), the similar adsorption energies are of the order of − 5.62 and − 7.12 eV. This clearly shows that the copper modified nickel surface show an improved resistance for coking tendency and have lower affinity for carbon deposition.
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Polyelectrolyte membrane PEM and fuelcell catalyst studies using a miniaturized PEM fuel cell test fixture
Authors: Stephen Creager, Saheed Bukola and Rhett SmithAdvances in catalyst and electrolyte materials for hydrogen fuel cells are driving performance gains and cost reductions that are helping to bring hydrogen fuel-cell technology to market. Research on new materials is always a combination of synthesis and characterization, where characterization must eventually include incorporation of materials into an operating fuel cell. It is at this stage that research on leading-edge new materials often stalls, because conventional fuel-cell tests require relatively large amounts of material, e.g. several grams of a new catalyst and tens to hundreds of grams of ionomer, corresponding to many tens of square centimeters of membrane area, are required to run a comprehensive set of tests as is necessary to assure reproducibility and examine behavioral trends. These amounts of material are often not available in early-stage synthetic work, which means that characterization uses other approximate approaches, e.g. rotating disk electrode (RDE) voltammetry to study catalyst activity, with true fuel-cell testing often being delayed until syntheses may be scaled up. This situation is unfortunate because approximate tests often do not adequately screen materials. It would be desirable to run preliminary fuel-cell tests at an early stage to gain a better idea of materials properties before making decisions regarding which materials to scale up. This contribution will present our recent work building and using a miniature PEM fuel-cell test fixture that uses only very small amounts of material to conduct a true solvent-free fuel-cell test. The cell is fabricated from a conventional compression-style fitting and uses 5/8 inch diameter graphite or metal rods for gas delivery and for making electric contact with the electrodes. Membrane-electrode assemblies (MEAs) are made from 3/4-inch diameter PEM disks, typically cut from Nafion ionomer membrane, onto which carbon-cloth-based electrodes are bonded by hot pressing. Electrode diameters range from 1/8 to 3/8 inch. The presentation will include recent published work demonstrating reproducibility and select MEA characterization data, including in-situ voltammetry to assess electrochemically active surface area (ECSA) of catalysts and polarization curve measurements that are easily obtained using conventional linear sweep voltammetry with a conventional laboratory potentiostat. This situation is in contrast to conventional fuel-cell testing that requires specialized instrumentation with passage of very large currents, e.g. tens of amperes. Very recent work using the cells in hydrogen pump configuration will also be presented. This configuration is particularly useful for measuring resistances to proton transport through ionomers in the direction through the membrane plane, in contrast to most measurements which focus on in-plane resistance, because it is easier to measure. Very recent work on the synthesis and properties of new tetra-aryl-phosphonium (TAP) alkaline ionomers which are expected have high alkaline stability and to be good hydroxide-ion conductors, and on the effect of single graphene layers embedded in Nafion membranes on proton and other ion conduction through the Nafion membranes, will also be presented.
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Impacts of DFIG Reactive Power/Voltage Control on Power System Oscillations through Mode Coupling
Authors: Wenzong Wang and Garng HuangIntegration of converter-control based renewable generators (CCBGs) into power systems introduces new dynamics and influences system stability. One particular concern is its impact on power system oscillations. Among different types of CCBGs, doubly-fed induction generators (DFIGs) have attracted the most attention. Reference [1]–[3] use the DFIG model with detailed control loops developed by General Electric (GE) and study its impact on power system small signal oscillations. It is observed that the DFIG reactive power/voltage control loop introduces an oscillation mode whose frequency is in the range of electromechanical oscillations (0.1 Hz to 2 Hz) [1]. DFIG's influence on the electromechanical oscillations is found to be highly dependent on parameters of this control loop [1, 2]. In [3], eigenvalue analysis is conducted for the Western Electricity Coordinating Council (WECC) system with projected high CCBG penetration conditions. An oscillation mode involving both wind turbine and synchronous generator (SG) state variables is observed. It is found that the wind turbine reactive power/voltage control variables have the highest participation in this mode. The observations in [1]–[3] indicate interactions between the DFIG reactive power/voltage control mode (referred to as VAR controller mode hereafter) and the SG electromechanical mode. However, the mechanism of the interaction and the conditions for strong interaction is not explored. Moreover, how this interaction affects the mode shapes of the two modes is not studied. Since the CCBG mechanical dynamics are separated from the grid by the converter interface, coupling between the CCBG converter control modes and the electromechanical modes becomes a critical way by which the CCBG dynamics can influence the electromechanical oscillations and it deserves through study. Based on the mode coupling theory, this paper reveals the interaction mechanism between the VAR controller mode and the SG electromechanical mode. Impacts of this interaction on power system oscillations are demonstrated and discussed. First, the VAR controller mode is investigated using damping torque analysis. Impact of operating condition change on its damping and frequency is shown analytically. The coupling between this mode and an electromechanical inter-area mode is then explored in a two-area test system. It is demonstrated that when frequency of the VAR controller mode approaches the inter-area mode, mutual participation increases and the influence of DFIG dynamics on the inter-area mode is increased. Additionally, it is shown that both positive and negative effect on the inter-area mode damping can be imposed depending on the VAR controller parameters. Moreover, the influence of mode coupling on mode shape of the two modes is investigated and it is demonstrated that the VAR controller mode, if becomes unstable, can couple with a well damped inter-area mode and cause unstable inter-area oscillations. In other words, in this situation, the unstable local voltage oscillation at the DFIG wind farm will propagate to other areas of the system and cause detrimental effect to the system. This study has practical merits. Challenge of wind generator voltage control on weak grids has been identified in the Electric Reliability Council of Texas (ERCOT) system [4]. Voltage and power oscillations close to a wind power plant were observed in ERCOT, following the outage of a nearby transmission line [4] or update of its controller settings [5]. Voltage controller is identified as the source of oscillations [4, 5]. The study in this paper offers insights into the VAR controller mode and demonstrates that not only local oscillations, but also inter-area oscillations can be caused by improper setting of the DFIG VAR controller or change in system operating conditions close to the DFIG plant. The key findings and conclusions of this study are summarized as follows: The DFIG VAR controller mode is sensitive to the system operating condition close to the wind generator. The voltage control scheme of DFIG is more prone to instability than the reactive power control scheme and the damping of the VAR controller mode decreases when the system becomes weaker at the DFIG interconnection point.When frequency of the VAR controller mode approaches an inter-area mode, the followings are observed: 1) mutual participation of the two modes increases; 2) the influence of DFIG dynamics on the inter-area mode damping increases; 3) mode shape of the VAR controller mode changes to involve inter-area oscillation of the SGs. When mode coupling is strong between the two modes, unstable inter-area oscillations can be caused by two mechanisms: 1) a stable VAR controller mode contributes negative damping to the inter-area mode 2) the VAR controller mode becomes unstable and couples with a sufficiently damped inter-area mode (change in VAR controller mode shape) and cause inter-area oscillations. Both situations can be severely detrimental to the system and should be carefully studied to avoid them.Proper settings of the VAR controller can also increase the inter-area mode damping. Results of this study can be generalized to other types of CCBGs since they have the same VAR controller structure (based on models in PSS/E). Thus the potential coupling between the VAR controller mode and the inter-area mode is generic for CCBGs. [1] G. Tsourakis, B. Nomikos, and C. Vournas, “Effect of wind parks with doubly fed asynchronous generators on small-signal stability,” in Electr. Power Syst. Res., vol. 79, no. 1, pp. 190–200, 2009. [2] L. Fan, Z. Miao, and D. Osborn, “Impact of doubly fed wind turbine generation on inter-area oscillation damping,” in Proc. IEEE Power Eng. Soc. Gen. Meeting, 2008, pp. 1–8. [3] J. Quintero, V. Vittal, G. T. Heydt and H. Zhang, «The Impact of Increased Penetration of Converter Control-Based Generators on Power System Modes of Oscillation,» in IEEE Transactions on Power Systems, vol. 29, no. 5, pp. 2248-2256, Sept. 2014. [4] S-H. Huang et al. “Voltage Control Challenges on Weak Grids with High Penetration of Wind Generation: ERCOT Experience,” in Proc. IEEE PES General Meeting, San Diego, CA, July 2012, pp. 1–7. [5] Technology solutions for wind integration in ERCOT, [Online]. www.electrictechnologycenter.com/pdf/TPR2Rev0Chg0043014.pdf
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Improve the production of two Qatari date palm cultivars ShiShy and Lulu for food security
More LessThe response of plant tissue to standard growth media varies widely due to the genetic diversity of the plant cultivars studied. The objective of this research was to determine the effects of micronutrients on date palm growth and which of these micronutrients are critical for improving growth combined with Paclobutrazol or without on in vitro of elongation stage. In vitro growth of two cultivars was determined by varying five treatments that included minor salts (EDTA-chelated iron, Cuso4,) alone or combined with Paclobutrazol. The effects of these five treatments of plantlet length, trunk thickness, rooting number and Chlorophyll A, B were investigated. The results obtained after three months showed that, increase copper sulphate on MS elongation media combined with Paclobutrazol was more effective for increasing strongly of trunk thickness as well as rooting number compared with normal MS level. While poor response was found when increase of Fe in the chelated form of Fe-EDTA on MS elongation media. For cultivars, shishy gave the highest plantlets length as well as root number, while the increase of trunk thickness was achieved with cultivar LuLu. The greatest formation of chlorophylls A, B was observed when increase copper sulphate on MS elongation media with cultivar LuLu. The survival rate after 3 months was related to the medium used during the elongation phase, the survival of plantlets reached to 98.66% with cultivar lulu at the acclimatization stage.
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Initial Results from a Study on Greywater Reuse in Qatar: Economic Benefits and Public Opinions
Authors: Jordan M. Lee and Dr. Laurent A. LambertDue to low annual rainfall and depleted groundwater resources, Qatar relies on expensive and energy-intensive desalination and retreatment plants to meet its growing water demand. With a high consumption rate of 557 liters/day/inhabitant, the cost of desalinating, transporting, and retreating water represents an unnecessarily large financial burden for the state. The Tarsheed national awareness campaign and tariff increases in Qatar are helping temper the rise of these costs, but additional tools are required to counter growing water demand. This study explains how recycling greywater can mitigate the growth of Qatar's water expenditure by slowing the increase in demand for desalinated seawater and retreated wastewater. Greywater is gently used water from showers, washing machines, swimming pools, air conditioning units, and lavatory sinks. Greywater is distinct from more heavily polluted blackwater, which comes from toilets, kitchen sinks, and dishwashers. Recycling greywater can generate savings because, with little or no treatment, greywater can replace more expensive water resources for several purposes, especially garden irrigation and landscaping. For example, using greywater instead of desalinated water for landscaping can slow the growth of demand for desalinated water in Qatar, thereby tempering the increasing cost of desalination subsidies. Capturing and reusing greywater will also slow the growth of the quantity of wastewater that is transported to retreatment plants and purified, which will generate further savings for the state. While there is a small cost to install a greywater capture and treatment system on a building, it pales in comparison to the cost of the desalinated and retreated water that would otherwise be used. This study provides quantitative information on the annual savings that can result from recycling different percentages of Qatar's greywater resource. Savings were calculated by assuming a quantity of greywater to be recycled (ranging from 5% to 30% of total greywater in Qatar), and then determining the cost of desalination, transport, and retreatment for that quantity of water. The savings from recycling the selected quantity of greywater equal the sum of the desalination, transport, and retreatment costs. Using this process, this study finds annual savings ranging from QAR 50 million to QAR 755 million. The large range in savings estimates is due to differences in the amount of greywater recycled, and differences in cost estimates for desalination and wastewater transport and treatment. Cost data were collected through interviews with water provision stakeholders, from executives to workers in the field, as well as a review of literature on the industry. In addition to this economic analysis, this study uses SESRI survey data to show that Qatar's population is highly accepting of greywater use, with 82% of Qatari citizens and 91% of white-collar expatriates saying that they are wiling to use greywater for landscaping. The survey was conducted by telephone and includes data from a nationally representative sample of 746 Qatari citizens and 740 white-collar expatriates. The findings of this research align well with those of greywater research projects in Oman, which have concluded that recycling greywater will generate notable savings, and that there is strong public support for use of the resource. By recycling greywater, Qatar can slow the growth of its water provision costs, improve its water security, and advance its goal of sustainable development.
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An Integrated Approach for Enhancing Food Safety in Qatar
This study was carried out to assess hygiene conditions, food handling practices, food safety knowledge of food service providers (FSPs), and the microbial quality of food served in different food service establishments in Doha. Fifty-three FSPs were randomly selected among 200 FSPs. Face-to-face interviews with the food safety managers at each participating FSP were conducted using a survey consisting of 40-questions (demographic data on workers, HACCP training, knowledge on personal hygiene, and safe-food handling practices) in October-December 2015. In addition to survey questionnaire, a checklist was used to determine the implementation of international food safety standards by observing actual practices applied at each FSP. All FSPs who took part in the initial survey were also invited to participate in one of three one-day educational workshops focused mainly on important components of food safety management system and held in 2016. At the time of workshops, each participant was also encouraged to take part in the microbial quality assessment study. Out of 53 establishments, only 10 FSPs (2 fine-dine-in, 2 casual sit-in, 2 catering, 2 fast-food, and 2 takeaway) accepted to provide food and swab samples from their entities. At the time of each visit to select FSPs, various menu items (food cooked in a short time, ready-to-eat foods, vegetables, dairy-based deserts, sandwiches, and raw seafood, e.g. oysters) were sampled in duplicate (based on the daily menu prepared at the time of sampling) at different food preparation stages (receiving, food storage, food preparation, holding/cooking, and serving). The microbial quality of food samples (n = 105) served and swabs collected from food preparation surfaces (n = 58) were also assessed using select media (APC, MCA, XLT4, and LSA). The identification of positive samples was carried out using VITEK-2 system. After the microbial assessment, a follow-up survey consisting of 24 questions was developed to determine the impact of the educational trainings on food service providers' daily operational practices. The FSP managers who participated in the initial survey were invited by phone or email or in person to take part in the follow-up survey. Out of 53 FSPs, only 16 were available to answer the questions due to reasons beyond the control of the research team. The major reasons for a low participation were 1) several managers moved back to their country without any contact information, 2) many of them changed their jobs and there was a no way of communicating with them since they did not provide an alternative email or a phone number. The survey results indicated that average service years of FSPs was 11, the average age of food safety managers interviewed was 33, most managers (66%) had college degree, and 68% of them were trained on HACCP. It was demonstrated that casual-sit-in and fine-dine-in restaurants are the only FSP types which consistently kept records (100%), followed by fast-food (36%), and catering (14%) FSPs. The microbial analysis indicated that the average APC in food samples collected from all FSPs met the international standards, while the APC counts of swab samples were considered unsatisfactory since the levels were above 106 Log10 CFU/cm2. The highest bacterial count was reported in swab samples (7.26 Log10 CFU/cm2) collected from preparation area in takeaway restaurants. Concerning the target organisms (Escherichia coli, Salmonella spp., and Listeria monocytogenes), among 105 food samples and 58 swab samples collected, 13 samples (8%) exhibited positive results for possible target pathogens. Positive samples were identified as Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa, and Pantoea spp. Overall, the participants were highly satisfied (average score: 4.39/5 ± 0.20) with the information presented in the training workshops held in 2016, indicating that the workshops helped improve their knowledge on food safety; change their attitudes towards safe handling foods, and inform them about the changes on food safety laws and regulations in Qatar. These results provided insight information on the aspects of behavioural changes that confirm the value of intervention studies. One important note which is important to mention that the participating managers indicated that they need open communication between the policymakers and the FSPs to be able to make sure that they will not be left behind if there is any changes/updates on food safety rules and regulations applied in the country. This issue is going to be addressed by posting constant updates on GSO (food safety standards applied in Qatar) on the website recently developed and hosted under the Ministry of Public Health website. Results obtained in this study might help food safety managers in these select FSPs to better understand the need for implementing effective control measures in order to prevent contamination and eventually protect the public health.
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A Behavioral Approach to Food Waste Issue in Qatar
Introduction: Food and Agricultural Organization (FAO) defines food security as stable access to sufficient, safe, and nutritious food. Food waste is a global and complex problem that affects each of three pillars of sustainable development: environment, economic, and social (FAO, 2013). Food loss is defined as the decrease in quantity or quality of food, whereas food waste is the removal from the food supply chain of food which is fit for consumption, or which has spoiled or expired mainly due to economic behavior, poor stock management, or neglect (FAO, 2014). Food loss occurs upstream of the supply chain, particularly post-harvest losses have drawn attention. On the other hand, food waste is observed more frequently downstream the supply chain, specifically at the retail and consumption stages. The FAO estimates that around one-third of edible parts of the food produced for human consumption in the world get lost or wasted globally, which correspond to about 1.3 billion tons of food per year. Food waste is closely associated with food security as being able to reduce food waste will help feed more people and reduce the pressure on natural resources whilst alleviating the negative impact on environment due to greenhouse gas emissions from food chain operations and loss of biodiversity due to agricultural activities. Especially in developed countries consumers are considered to be one of the main sources of food waste and therefore in the past few years an increasing number of studies has examined food waste and consumer behavior. The food waste cannot be explained by a single behavior, but rather a combination of multiple behaviors that can increase or decrease the likelihood of food being wasted. The aim of this research is to synthesize the existing work on consumers' food waste behavior and to develop a comprehensive conceptual framework and to empirically test this framework with data from a country that is dependent on foreign food imports, leading to growing concerns about food security: Qatar. With an increasing population and the food provision depending on imports that comprise more than 90% of the food consumed in Qatar, food security is a top priority. This paper is a research outcome of the SAFE-Q Project, which aims to contribute to food security efforts in Qatar with a holistic approach to understanding food distribution, food consumption, and food waste.
Research Approach: Our synthesis of previous work explaining the food waste behavior suggests that the Theory of Planned Behavior (TPB) sets a strong basis for explaining it. The TPB provides a theoretical framework that is commonly used for systematically explaining behavior (Ajzen, 1991). We build a conceptual framework extending the TPB (personal attitudes, subjective norms, perceived behavioral control, intentions, behavior) with six additional constructs identified through our extensive literature review and empirical work in Qatar: motives, financial attitudes, planning routines, social relationships, food surplus, and Ramadan (Aktas et al., 2017). We developed an online questionnaire and collected data from Qatar in English and Arabic. We then used partial least squares structural equation modelling to explain the food waste behavior. Results and Discussion In line with the TPB, we find a negative relationship between perceived behavioral control and intentions, where the perceived behavioral control construct has indicators measuring the “difficulty to control food waste”. The relationship between intentions to reduce waste and the amount of food waste is negative, where we conclude the intentions to reduce waste help reduce the behavior leading to food waste. The positive relationship between personal attitudes and intentions suggest that attitudes towards food waste positively affect the intentions to reduce food waste. We find a strong negative relationship between perceived behavioral control and intentions to reduce waste. When it is difficult to control the food waste, the intentions to reduce it are low. Both food choice motives and financial attitudes positively affect the planning routines. While planning routines help reduce the food surplus, the social relationships construct that reflect hospitality and eating with others result in higher food surplus. A unique finding of our research is that the contextual construct Ramadan is found to be positively associated with food waste behavior. Understanding the contextual variables which affect consumers' food waste behavior could help developing strategies for food waste reduction. The findings reveal the strong impact of changing eating habits during certain periods of the year (Ramadan) and food surplus on food waste behavior. The food surplus as a contributor to food waste is explained by planning routines and social relationships (hospitality, risk averseness towards not having enough, cultural habits around how food is served). Impact and Conclusion Food has a significant role in economic, social, political, and cultural lives. By adopting or avoiding certain behavior patterns regarding food, individuals can contribute significantly to environmental, social, economic, and political sustainability. Therefore, it is important to understand the motivational and structural factors and processes that facilitate or are barriers to reducing food waste behavior. Our research helps increase the awareness around food waste and maybe used as a lever to change consumer behavior towards reducing surplus food at households, which is wasted if not consumed in time. Minimizing the surplus food wasted at the end of the value chain is the most impactful objective since it minimizes the loss of the highest value added after food is grown, harvested, processed, packaged, stored, transported, and distributed.
References
Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50(2), 179‒211.
Aktas, E., Topaloglu, Z., Oledinma, A., Sharif, A., Huda, A. K. S., Sahin, H., and Irani, Z. (2017). Contextual Factors Affecting Food Security: A Behavioural Framework. In: The 22nd Logistics Re- search Network Annual Conference and PhD Workshop. 6–8 September, Southampton, UK.
FAO (2013). Food wastage footprint. Impacts on natural resources. Summary Report. http://www.fao.org/ docrep/018/i3347e/i3347e.pdf. Date accessed: 31 October 2017.
FAO (2014). Definitional Framework of Food Loss. Working Paper. http://www.fao.org/3/a-at144e.pdf. Date accessed: 31 October 2017.
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Isolation of Qatari bacterial bioagents that have unique characters from date palm environment
Authors: ALI El Kharbotly, Noha El Badawy, Marwa Saadaoui, Mohammed Hassanein and Masoud Al-MarriIdentification of biological agents which is thermo- tolerance is a key success for biological control in the arid regions such as Arabian Peninsula. Date palm is one of the indigenous plants in this region. It can tolerate high temperature and survive the drought. It is expected that microbial communities associated with date palms would have similar characters. It would be reasonable to search for bio-agents from such microbial communities. This study is a apart of a project to identify microbial communities living in the phyllosphere and rhizosphere of date palms. Bacterial colonies were isolated from date palm leaflets and soil samples containing date palm roots. Samples were collected from the date palm experimental field at the Agricultural Research Farm, Rwdet Al-Faras, Qatar. Isolation of bacteria were conducted on nutrient agar media using the standard techniques. Hundred eighty five bacterial isolates were obtained. They were evaluated for their antagonism potentiality against Alternaria alternate as a causal agent for leaf spot diseases in date palm and Fusarium solani and Macrophomina phaseolina as causal agents for root rot in Phaseolus vulgaris crops. Suppression of mycelial growth of the pathogens were recorded as the result of the interaction between the pathogen and different bacteria. Two modes of action were observed. Eleven isolates grew on the area of inoculation but they suppressed the pathogen by their extracellular antifungal metabolites while the growth of 18 isolates spread all over the plate and prevented pathogens from growing either by their growth or by both the growth and the extracellular antifungal metabolites. Screening for thermos-tolerance were carried out by picking up a single colony from each bacterial isolate, inoculating it in 1 ml of LB liquid media and incubating the culture at 90 °C for 24 hours. Then they were cultured on nutrient agar media plates, incubated at 30 °C for 24 hours. The two separate evaluations of antagonism and thermos-tolerance of the bacterial isolates showed that only 18 isolates had both characters. These 18 isolates were exposed to high temperature then evaluated for their antagonism. Only 7 isolates kept their potential to suppress the growth of pathogens. This test demonstrated the possibility of losing the antagonism effect as a result of high temperature. In this test 90 °C/24 hours was used. Molecular identification was carried out to on the seven bacterial isolates. They were identified based on 16s rDNA sequencing using universal primers and standard procedures. They were Pseudomonas putida (3 isolates), Bacillus subtilis (2 isolates) and Bacillus megaterium (2 isolates). These species were reported to have a potential as a bioagents and some of their isolates were developed and being used commercially as biopesticide. We do not recommend using Pseudomonas putida as biopesticide because they might have a potential risk for human. They can cause infections in cases of immunocompromised patients It can be concluded that both thermos-tolerance and antagonism are important to have a successful bio pesticide in the arid region. Losing the antagonism after exposing to high temperature showed the importance of evaluating each bio-agent for this character. So far we did not elucidate the mechanism of losing the antagonism. In this experiment, a very high temperature for long time was used however using lower temperatures for shorter periods can reveal different results.
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Establishment of an Efficient in Vitro Regeneration Protocol for Mass Propagation via organogenesis of Endangered Plant Rhanterium epapposum in Qatar
Authors: Fatima hassan Ibrahim, Maha Talib Alhenzab and amira Omer ElbadawiWild plants make an important contribution to the life of localcommunities. Endangered plant species like Rhanterium epapposum olive (Arfaj) were micropropogated through tissue culture technique in order toprotect them from extinction and conserving Biodiversity in Qatar. Agriculture Research Department (ARD) has developed anefficient protocol for rapid and large scale in vitro propagation of the nativeannual plants Rhanterium epapposum that cannot be propagated on alarge-scale by means of seeds and cuttings. Apical bud and nods were collectedfrom wild habitat and cultured on modified Murashige and Skoog (MS) mediumsupplemented with 1.5 mg l-1 BA (initiation stage) and containing 1 mg l-1 BAP+0.2 mg l-1 Kinetin for multiplication stage, reculture three times withregular transferring to fresh medium containing the same composition medium.For rooting stage, elongated shoots were cultured on differentstrength of Murashige and Skoog (MS) media(full and ½) supplemented with different auxin. ½ MS nutrient medium containing1 mg l-1 IBA increased significantly the number of roots and root length compared with othertreatments. The plantlets were adapted to greenhouse conditions successfully
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Directload control experiments and case studies in Qatar Foundation Community Housing
More LessEnergy security is one of the main national concerns, with population's growth and energy demand increase it becomes critical for countries to address the issue. Increasing energy production is extremely costly and could require investments to modify the power network infrastructure that is also expensive. Demand Side Management is a collection of methods and strategies that helps modifying the demand of consumers in order to cope with the limited energy production, avoiding tremendous expenses. DSM is often associated with the residential load profile in order to determine two aspects. Firstly the residential energy load profile is the main component that is required in order to understand how to apply DSM effectively. The load profile is often too complex, it exhibits unique patterns and characteristics as it is influenced by a number of social and economic factors, climate and the local policies also impacts the profile. Secondly the residential load profile has a useful role that helps us identify the viability of using solar photovoltaic and storage systems in households. The residential energy consumption represents a large portion of Qatar's total energy consumption and it is growing larger. By monitoring the energy profiles of 10 households chosen from different accommodation types, we can log and plot actual load profiles that can represent the domestic household energy profile of a province. The monitoring of the loads has to cover a yearlong period in order to demonstrate the climate impact on the load profiles. The energy consumption is represented by household appliances and mostly by HVAC or heating depending on the country's location. The loads are split into two categories, an elastic load that can be fixable for the user to operate at various times. The other type of loads is inelastic loads that have priority that impacts the comfort level of the user and cannot be shifted. These loads play a role in determining the shape of profile and the extent of degree to which it can be changed. The best way of monitoring the loads is through nonintrusive appliance load monitors in order to keep occupants disturbance at minimum. Smappee is a nonintrusive appliance load smart monitor that offers precision in energy reading as well as a remarkable user interface. These monitors measure the total energy consumption using current transformers. It logs power readings with a five minutes interval and uploads it to the cloud. The data can then be downloaded to a local server in order to be plotted into the load profiles. Ten Smappee monitors were installed in ten different houses and apartments in Doha during June and July 2017 and are expected to run for a year. The data will be used to plot a representation of Qatar's typical domestic load profile and to investigate the two aspects of DSM and the viability of PV and storage systems. A simple case study is carried out to assess the potential of DLC in the Education City Community Housing (ECCH). The ECHH accommodates the QF employees in a high-quality villas and apartments that ensure a high living standard. The ECHH consists of two lots that made of totally 639 housing units classified into five different dwelling types. Furthermore, the AC units installed have three different capacities (18, 11, 8 kW) and the capacity of the AC unit depends on the type of the housing unit. Table 1 EC Community Housing units by type of unit, area, and AC unit capacity Housing Type Area (m2) No. of Units AC Load (kW) Total Load Standalone V. Type 1 408 52 18 936 Standalone V. Type 2 389 17 18 306 3 Bedroom Attached V. 315 118 11 1,298 2 Bedroom Attached V. 219 108 11 1,188 3 Bedroom Apt. 256 72 11 792 2 Bedroom Apt. 161 200 8 1,600 1 Bedroom Apt. 109 72 8 576 Figure 1 Peak demand reduction achieved by the three different scenarios in the total electricity demand in Qatar.The case study comprises three scenarios; the first scenario is assuming 15-minute cycling for all buildings is performed. The second scenario is assuming 50% of the residents went on summer vacation, and their AC is cycled for 1 hour and 50% stayed here and their AC is cycled for 15 minutes in 4 groups such that the first group is cycled in the first 15 minutes of the hour, then the second group in the second 15 minutes of the hour and so on. It is believed that more than 50% of the residents leave the country for summer vacation, so the third scenario is similar to the second however, it is assuming 80% of the residents went to summer vacation and 20% stayed in Qatar. The results of these three scenarios are presented in Figure 1. Around 1.674 MW demand reduction could be achieved in the first scenario, while it could be increased if the long summer vacations are taken into consideration as seen in the 2nd and the 3rd scenarios where 3.557 MW and 5.44 MW demand reduction is achieved respectively. Such results provide critical insights in assessing demand reduction potential of Qatar and determining associated economic savings.
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Reinforcement of copolyamide membranes for water treatment applications
Authors: Patrik Sobolciak, Aisha Tanvir, Anton Popelka, Mohamed Hassan, Khaled Mahmoud and Igor KrupaClean water is the key element for all living organisms to sustain life. However, due to the rapid industrialization and large increase in the population, the contamination of water resources is important issue occurred globally as well as locally here in Middle East region [[1]]. From past few decades, various techniques for treating the wastewater have been developed. Among others, filtration techniques are a commonly used to eliminate contamination of water caused by various materials such as heavy metals, dyes, oil, bacteria etc. Robust, capable membranes are crucial for effective filtration process and various polymeric materials have been studied in last decades. Among others, polyamides membranes have been used as membranes due to their favourable properties such as good thermal and mechanical stability [[2]], which make them suitable for the designing of fibres, mats and membranes. Compared to many commercially available filtering membranes that are produced by conventional fabrication techniques such as phase inversion technique, the pore size distribution of electrospun fibrous membranes can be conveniently tailored in the range of sub-microns up to a few micrometers via simply adjusting the material and process parameters of electrospinning and related post-processes. In addition, electrospun filtering media are also capable of maintaining a high porosity, which guarantees the high-flux liquid filtration.One of the approach to further improved efficiency, mechanical performance and lifetime of membranes is using various fillers.Nanocelluloses are particularly interesting because of their environmental friendliness, high mechanical performance, flexibility, low-cost, versatility, and tailorable surface functionalities. The size, structure, and functional groups of nanocelluloses are dependent on the source of cellulosic fibres and preparation method [[3]].Other nanofillers, very recently discovered with large potential in water treatment applications are MXenes. MXenes are a new class of 2D metal carbides and carbonitrides, which are both conductive as well as hydrophilic [[4]]. MXenes have general formula Mn+1Xn, derived from MAX phases, where M is an early transition metal, A is an A-group element, mostly IIIA and IVA, or groups 13 and 14, and X is either carbon and/or nitrogen, by chemical etching in HF or NH4HF2 solutions, where n = 1, 2 or 3. The unique structure of MXenes offers combination of excellent mechanical properties, hydrophilic surface, transparency and metallic conductivity. Herein, we used electrospinning to prepared novel membranes based on copolyamide 6,10 reinforced by nanocellulose prepared from Qatari date palm waste and MXene 2D nanofillers which dramatically improved mechanical performance and separation efficiency of the membranes compared to neat copolyamide membranes. Prepared membranes were able to separate oil (vegetable and diesel) from water with efficiency over 96 % regarding of membrane composition and separation conditions. Additionally membranes exhibited good lifetime with maintaining high efficiency of separation. Acknowledgements This work was made possible by NPRP grant No.: 7-1724-3–438 from the Qatar National Research Fund (A Member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. References [[1]] A.D.N. Nemerow, Industrial and Hazardous Waste Treatment, Van Nostrand Reinhold, New York, 1991. [[2]] G.-R. Xu, J.-N. Wang, C.-J. Li, Strategies for improving the performance of the polyamide thin film composite (PA-TFC) reverse osmosis (RO) membranes: Surface modifications and nanoparticles incorporations, Desalination 328 (2013) 83–100. [[3]] A.C.W. Leung, S. Hrapovic, E. Lam, Y. Liu, K.B Male, K.A. Mahmoud. Characteristics and Properties of Carboxylated Cellulose Nanocrystals Prepared from a Novel One-Step Procedure. Small 7(3) (2011) 302-5. [[4]] M. Naguib, M.W. Barsoum, Y. Gogotsi. 25th Anniversary Article: MXenes: A New Family of Two-Dimensional Materials. Advance Materials 26(7) (2014) 992 - 1005.Acknowledgements This work was made possible by NPRP grant No.: 7-1724-3–438 from the Qatar National Research Fund (A Member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. References
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Effects of Drill Mud and Drive Torque Sinusoidal Excitation on Drillstrings Lateral and Torsional StickSlip Vibrations
More LessOil and gas drilling companies spend around 20$ billion annually from which 15% is attributed to material and productive time losses. The most prevalent drilling problems are caused by the Bottom-Hole-Assembly failure which includes drill string and drill bit damage or fatigue failure. During normal operation, to achieve penetration that cannot be met by the drilling motor power section, the bit torque generates an increased reactive torque that acts in the opposite direction of the driving rotation. This sudden increase in reactive torque is transmitted through the drill string as torsional ‘stick-slip’ vibration, which is often regarded as one of the most damaging modes of vibration. Due to cyclical rotation acceleration and deceleration of the bit, Bottom-Hole-Assembly, or drill string, this phenomenon produces accumulation and release of energy stored as several turns of twist in the rotor. While downhole vibrations are difficult to prevent and cannot be totally eradicated, implementing of corrective methods may be highly efficient for drilling optimization. In the present work, the effect of drill mud on drilling dynamics is studied, then, a sinusoidal excitation is added to the drive torque and resulting impact on downhole equipment is presented. A laboratory scale arrangement consisting of a flexible rotor and a stator is used, and attention is paid to whirling and stick-slip motions of the drill string. The results are provided in the form of responses in the time and frequency domains. A non-linear coupled dynamic model of a rotor enclosed within a stator and subjected to non- linear mud film force is developed. Comparisons with simulations data are also included. The work is one of the first studies carried out on the influence of adding a sinusoidal excitation to the driving torque with the use of drill mud on drill-string whirling motions in a laboratory environment.
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Efficient and fast separation of emulsified oil/water mixtures with a novel micro/nanofiber network membrane
By Zhaoyang LiuProduced water is one of the largest waste streams emanating from oil and gas industries. If inadequately treated, emulsified oil droplets contained in produced water will contaminate the environment and subsequently pose severe threat to human health. Removal of tiny emulsified oil droplets in produced water is very challenging. In this study, we demonstrated a new concept for constructing oil/water separating membranes with ultra-long titanate nanofibers (over 30 μm in length) / cellulose microfibers. An integrated network membrane was achieved with these ultra-long micro/nanofibers. This new membrane demonstrates good mechanical flexibility, which are critical for practical applications. This membrane shows high separation efficiency (99.9%) for oil/water emulsions with oil droplet size down to 3 μm, and at the same time has high water permeation flux (6.8 × 104 L m-2 h-1 bar-1) at low operation pressure. The high water flux is attributed to the interconnected porous structure throughout the whole membrane, while the nanoporous selective layer contributes to high oil separation. In addition, the low-cost materials and fabrication process for this membrane suggests its great potential for industrial scale-up.
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Edgefunctionalized graphene nanoplatelet towards energy storage application
Authors: Lagnamayee Mohapatra, Ahmed Sodiq, Fathima Fasmin, Belabbes A Merzougui and Rachid ZaffouWith the increased demand in energy resources, great efforts have been keen to develop advanced energy storage systems. A redox flow battery is a type of rechargeable battery where rechargablity provided by two chemical components dissolved in liquids and separated by a membrane. Energy is stored in the liquid electrolyte in external tanks, rather than in the battery cell. Flow batteries are technically similar to fuel cells are targeted at large-scale energy storage solutions. [1] Graphene based materials have attracted great attention for used as an alternative electrode materials for electrochemical energy storage system due to its unique properties of large surface area, chemical stability, super mechanical flexibility, high electric and thermal conductivities and an atomic thick two-dimensional sp2 hybridized carbon network. [2]To realize commercial use of graphene-based energy devices, it is highly desired to produce high-quality graphene at a low cost and large scale. Functionalization of graphene can further enhance its properties for efficient energy conversion and storage. Several innovative methods have been reported recently for functionalization of graphene, including mechanical exfoliation, surface polymerization vapor deposition (CVD), chemical exfoliation of graphite, sonication/intercalation,but these suffer from high manufacturing costs and technical difficulties.[3] Chemical doping of graphene with heteroatoms (e.g. Nitrogen) is one of the most feasible approaches to modulate its electronic properties. Traditionally, these methods often requires complicated processes and/or chemical reagents containing additional undesirable components in their structures. On the particular interest, mechanochemical ball milling process is a simple but efficient approach for producing edge-functionalized graphene nanoplatelets in large quantity and low cost. Previously, N-doped graphene materials generated by ball milling of graphite with N-containing gases like N2 and NH3 have been showed good electro catalytic activities for oxygen reduction reaction (ORR). [4,5,6] But,the amount of Nirogen doping is not sufficient in the above case. Therefore, we prepared N-doped graphene (N-GNP) by ball milling of graphene nanoplatelet (GNP) with melamine, which is nitrogen-rich solid organic compound and followed by pyrolysis. Both the temperature as well as the mass ratio between GNP and melamine affect the nitrogen content. In the ball milling process, the strong shear forces generated between high-speed rotating balls caused the mechanochemical cracking of the graphitic C– C bonds and spontaneous incorporation of Nitrogen from melamine at the broken edges of graphitic frameworks as well as the consequent exfoliation of graphene nanoplatelet. From the XRD, the (N-GNP) has peak broadening, indicates the occurrence of the ball-milling-induced edge doping of GNP. The XPS plot reveals the presence of three different nitrogen species in the (N-GNP), namely pyridinic, pyrolic and quaternary Nitrogen. The as fabricated materials used as a slurry electrode and their performances were investigated for VO2+/VO2+ redox couple for vanadium redox flow battery (VRB). The cyclic voltammetry (CV) results revealed that the Nitrogen functionalization of Graphene noplatelet allowed remarkable improvements in terms of both the reversibility and the current density than as received GNP. Electrical impedance spectroscopy (EIS) was used to further investigate that N-GNP is showing highest conductivity than GNP. Enhanced performance of N-GNP in terms of electrochemical activity and kinetic reversibility is owing to its electrical conductivity, surface area, graphitized surface and chemical stability of the electrodes affects the overall battery efficiency. References 1. P. Leung a, A.A. Shah, L. Sanz, C. Flox, J.R. Morante, Q. Xu, M.R. Mohamed,C. Ponce de Leon, F.C. Walsh, Journal of Power Sources, 360,2017, 243-283.2. H.-M. Tsai, S.-Y Yang, C.-C. M. Ma, X.F. Xie, Electro analysis, 2011, 23, 9, 2139 – 2143.3. RoshniYadav, C.K.Dixit, Journal of Science: Advanced Materials and Devices,2017, 2141-149.4. H. Wang, T. Maiyalagan, X.Wang, ACS Catal. 2012, 2, 781 − 794.5. W. Shi, K.-Hsu Wu, J. Xu, Q. Zhang, B.Zhang,D. S. Su, Chemistry of Materials, 2017, 29, 8670-8678.6. L. Dai, Y. Xue, L.Qu, H.-J. Cho, J.-B. Baek, Chem. Rev., 2015, 115, pp 4823–4892.
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Epibenthic assemblages on vertical artificial substrates: recruitment and succession patterns in offshore Qatari waters
Artificial structures get introduced into the marine environment by accident (e.g., shipwrecks) or intentionally, for logistical (i.e., coastal protection), industrial (i.e., oil exploitation) or biological habitat enhancement (i.e., artificial reefs). Similarly to other types of man-made submerged structures, offshore oil and gas platforms provide adequate hard substratum for the development of sessile marine invertebrates and to increase habitat and food availability for fishes and other motile marine organisms (Svane and Petersen, 2001). Furthermore, offshore platforms generally face minimum external interference and are usually located in waters with strong currents, which facilitate larval dispersal and settlement. Despite the fact that there are currently more than 800 offshore oil and gas platforms in the Arabian Gulf (Sheppard et al., 2012), scarce information exists about the biological assemblages associated to these structures (Burt et al., 2012; Stachowitsch et al., 2002). In fact, oil and gas platforms are high-security areas with an exclusion zone of at least 500 m around the structures (Kashubsky and Morrison, 2013), which prevents fishing and other human impacts, but also restricts sampling for scientific purposes. Considering the substantial habitat and diversity losses of natural reefs in recent years, the perceived ecological role of these offshore structures is gaining increasing recognition. Several research and industrial programs have tried to promote the transition of decommissioned platforms into artificial reefs (e.g., Rigs to Reefs, Reggio Jr, 1987). It is vital, therefore, to study the community structure in such isolated marine habitats, to assess their structural and functional similarity and connectivity to natural marine ecosystems (Zintzen et al., 2008), in order to provide the scientific underpinning to the planning and decommissioning stage of the platforms. These issues are currently being addressed in the framework of the project “Connectivity, diversity and genetic flow between offshore natural coral reefs and oil platforms - NPRP No.: 7-1129-1-201”. In this specific study we aim to understand the recruitment and succession patterns of fouling communities offshore in Qatari waters, using stainless steel plates as artificial substrates, in order to mimic the stainless steel jackets, which generally support offshore oil platform in the Gulf. In October 2016, six vertical structures were deployed in the northeast of the Qatari Exclusive Economic Zone, in an area between the Al Shaheen oil field and natural offshore reefs, to investigate the source of the epibenthic species that colonize these artificial substrates. Each structure supports 30 stainless steel fouling plates (20 × 20 cm), spaced by 1 m, at depths ranging between 10 m and 45 m. Temperature data loggers (Onset TidbiT) were attached to the plate structures, at max and min depth, to investigate how the temperature and depth variations affect recruitment and development of fouling assemblages. All the structures were successfully retrieved during the first assessment, done 15 weeks after deployment, in February 2017. After all the plates were photographed and data downloaded from the temperature loggers, the structures were re-deployed in the same location. This imagery is currently being analyzed using the online platform CoralNet, to assess the percentage cover, abundance and diversity of the fouling assemblages. Preliminary results of this first assessment indicate strong invertebrate recruitment, with almost 100% cover of the plates, at all depths and locations. A clear vertical gradient was, however, apparent, with diversity and cover generally increasing with depth. Barnacles, bivalves, anemones and fenestrate bryozoans were dominant at shallow depths, while other types of macroinvertebrates, such as encrusting sponges, foliaceous bryozoans and hydrozoans, became more dominant as depth increased. As expected, important seasonal variations of seawater temperature (e.g summer-winter) were registered in shallow (< 10 m) and deep (> 40 m) layers. Variations observed in deep water (>40 m) during autumn and early winter were, however, larger than expected. High variability was found in all locations, with sea temperatures ranging 3-4°C during one single day. The semi-diurnal and lunar periodicity of these variations strongly suggests they are associated with tidal cycles. The full seasonal time series (one year), which will be available in November 2017, will allow the precise delimitation of the periodicity and magnitude of these temperature variations. The final data analyses will integrate data on temperature with depth and distance among structures to infer on recruitment and succession of sessile and mobile epifauna. References Burt, J.A., Bartholomew, A., Feary, D.A., 2012. Man-Made Structures as Artificial Reefs in the Gulf, in: Riegl, B.M., Purkis, S.J. (Eds.), Coral Reefs of the Gulf, Coral Reefs of the World. Springer Netherlands, pp. 171–186.Kashubsky, M., Morrison, A., 2013. Security of offshore oil and gas facilities: exclusion zones and ships’ routeing. Aust. J. Marit. Ocean Aff. 5, 1–10. doi:10.1080/18366503.2013.10815725Reggio Jr, V.C., 1987. Rigs-to-reefs. Fisheries 12, 2–7.Sheppard, C., Al-Husiani, M., Al-Jamali, F., Al-Yamani, F., Baldwin, R., Bishop, J., Benzoni, F., Dutrieux, E., Dulvy, N.K., Durvasula, S.R.V., Jones, D.A., Loughland, R., Medio, D., Nithyanandan, M., Pilling, G.M., Polikarpov, I., Price, A.R.G., Purkis, S.J., Riegl, B.M., Saburova, M., Samimi-Namin, K., Taylor, O., Wilson, S., Zainal, K., 2012. Environmental Concerns for the Future of Gulf Coral Reefs, in: Riegl, B.M., Purkis, S.J. (Eds.), Coral Reefs of the Gulf, Coral Reefs of the World. Springer Netherlands, pp. 349–373.Stachowitsch, M., Kikinger, R., Herler, J., Zolda, P., Geutebrück, E., 2002. Offshore oil platforms and fouling communities in the southern Arabian Gulf (Abu Dhabi). Mar. Pollut. Bull. 44, 853–860. doi:10.1016/S0025-326X(02)00085-1Svane, I., Petersen, J.K., 2001. On the Problems of Epibioses, Fouling and Artificial Reefs, a Review. Mar. Ecol. 22, 169–188. doi:10.1046/j.1439-0485.2001.01729.xZintzen, V., Norro, A., Massin, C., Mallefet, J., 2008. Spatial variability of epifaunal communities from artificial habitat: Shipwrecks in the Southern Bight of the North Sea. Estuar. Coast. Shelf Sci. 76, 327–344. doi:10.1016/j.ecss.2007.07.012
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A Systematic Approach for Designing Sustainable Industrial WaterEnergy Integration Network
Authors: Jamileh Fouladi and Patrick LinkeNatural resources face growing demands and constraints in many regions as a result of economic, population growth and climate change. Due to those changes, it is extremely essential to invest towards water and energy nexus integration technologies since integrated thinking and actions can led to achieving a sustainable development and global supply of water and energy. The water-energy nexus and integration has been recently proposed to minimize water-energy footprint of an industrial park. It is required to develop a systematic approach for water-energy nexus network and interconnections among the processes. Previous research works mainly have presented the general superstructure and approach to develop economically optimal water networks that achieve a specified footprint target. In this work, one of the previous approach for water network has been extended with cooling systems options in order to capture the linkages between water and energy within industrial cities. The objective of this paper is to develop a framework for optimizing energy and water resources from processes that have a surplus of energy at various qualities. A systematic procedure is developed for optimizing and maximizing the benefits of these nexuses, considering power generation from a net surplus of waste heat energy from each plant by accounting for different sustainability metrics. The developed approach includes the use of composite curve analysis to first identify the potential for excess heat and then used to develop the combined water-energy network. A superstructure is generated to embed various configurations and related optimization formulation is solved to obtain an optimal process that economically satisfies the demand for water and energy considering some environmental metrics. Special emphasis is placed on capturing the synergy potentials from utilizing excess process heat and synergies across cooling and desalination systems, as well as synergies with the surroundings in terms of power and water exports from the industrial cluster. The work considers multiple objectives to explore trade-offs between minimum total annual cost and environmental sustainability metrics. A case study of an industrial cluster of typical processes operating in Qatar is presented to highlight the benefits of integration. It is shown how economically very attractive solutions across the nexus are identified by the proposed optimization-based approach. The results indicate that by water-energy integration the footprint reduction can be significant while economically is attractive too. Therefore, there is a great potential for savings water-energy resources by water-energy integrations. The work is contributed to sustainable development such as less pollution and resource minimization.
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Determination of the levels of Particulate Matter 25 and 10 and their elemental Composition in Qatar
Authors: Ahmad Ali Ahmadi, Perumal Balakrishnan, Konstantinos Kakosimos and Ipek GoktepeParticulate matter (PM) pollution is one of the major environmental pollution issues severely affecting human health and air quality all over the world. Based on the recent World Health Organization (WHO) report, PM levels were considered relatively high in Qatar. This might mainly be attributed to arid climate, but also due to rapid industrialization and urbanization as well as traffic. The literature on PM pollution and its source is limited in Qatar and the region. Therefore, this study was carried out to assess the air quality at different locations in Qatar, identify the levels of PM2.5 and PM10, and determine the elemental composition of PM2.5 and PM10 to trace their sources. A total of 100 samples (60 for PM2.5 and 40 for PM10) were collected using SKC Deployable Particulate Sampler (DPS) System for 24-hr during the months of September 2016 to December 2016. The sampling was conducted at five different locations, namely, Qatar University (QU), Education City (EC), Al Waab street area (AD), Whole Sale Market area (WM), and Al-Wakrah City (AW). The elemental composition of PM samples was determined using an inductively coupled plasma optical emission spectrometry (ICP-OES). The relationship between the environmental conditions and PM levels were also established. The health risks associated with different PM levels was calculated using the US EPA Air Quality Index (AQI) tool. The overall mean concentrations of 24-hr PM2.5 ranged from 49.88 μg/m3 to 64.28 μg/m3, while PM10 levels were between 126.69 μg/m3 and 184.55 μg/m3. The four months mean concentrations of PM2.5 were determined to be 49.88, 64.28, 55.47, 58.84, and 56.52 μg/m3 at Qatar University, Education City, Al Waab, WSM, Al Wakrah city, respectively. The average 24-hr PM10 levels were 138.24 μg/m3 at QU, 156.44 μg/m3 at EC, 126.69 μg/m3 at AWb, 184.55 μg/m3 at WM, and 160.24 μg/m3 at AW. The concentrations of PM2.5 detected at each station exceeded the WHO guideline (20 μg/m3) by 2.5 to 3 fold during the study period. The presence of high concentrations of Ca, Fe, Al, Fe, Sr, Mn, Na, and Mg indicated the major sources of PM to be soil/crustal. The identification of Ni, Co, Cr, Cd, Ba, Pb, V, and Zn were directly related to anthropogenic sources, specifically due to fossil fuel combustion and vehicular emission and these levels were reported at the highest levels at the wholesale market station. The AQI levels reported at all stations indicated that overall air quality at Qatar University and Al Waab street area was considered to be Moderate for PM10 and Unhealthy for sensitive group for PM2.5 levels. While in Education City, Whole Sale Market, and Al-Wakrah city areas had unhealthy and unhealthy for sensitive group ratings for PM2.5 and PM10 levels, respectively. The statistical analysis on determining the effect of meteorological factors (temperature, humidity, and wind speed) on the concentrations of PM2.5 and PM10 showed that there is a significant relationship (P?0.05) between wind speed and temperature and PM levels at all stations. These findings highlight the need for more research on PM pollution 1) to determine seasonal levels since this study only covered four months (September-December), 2) to better understand the source of PM pollution (in addition to elements, the levels of Poly Aromatic Hydrocarbons should also be determined), and 3) to establish more effective control measures to protect public health and preserve the environment in Qatar.
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Distribution of the Endangered Haloxylon persicum Bunge ex Boiss &Buhse Ghada and conservation for food security In Qatar
More LessHaloxylon persicum Bunge ex Boiss &Buhse native and rare plant in the state of Qatar known as Ghada, Qadha, Rimth, it's endangered, high palatable species, a favored plant to stabilize sand dunes, conserve water and soil, prevent soil desertification, and improve environmental conditions. It's small tree or shrub to 3 m, trunk 10- 25 cm in girth; stem richly branched, glabrous; young branches slender, green; leaves 0.5 – 1.25 mm, scale-like, acute, connate into a cup, with a tuft of short hairs in the axil; flowers on short spicate branchlets. It's evergreen plant blooms at the end of August and during September. The freshly harvest seeds recorded high germination percentage but it's rapidly lost viability The species distribution in the Middle East, the species is distributed mainly in the Sinai Peninsula, Egypt, and central and northwestern Saudi Arabia on the Arabian Peninsula, the plant distributed in deep, often drifting sand. Previous studded recorded it east of Salwa at sand dunes (the area now known as Al Mashbiya), near the Saudi Arabian border. Haloxylon persicum used for grazed by camels; highly valued as firewood by Bedouin and desert villagers. Through years 2012 to 2017, the Genetic Resources Department, Department of Agricultural Research, Ministry of Municipality and Environment in Qatar collected, surveyed and has some inventory activities for flora in Qatar. but they did not record any distribution of Haloxylon persicum only recorded in Al Mashbiya at Lareeq the state of Qatar is home to some unique and important habitats, Qatar has very limited number of trees and shrubs but due to changes in land use, including increased development, camel overgrazing, human activities, habitat reduction has emerged as a significant threat to the biodiversity of this country. In the last decade, there has been increasing effort to protect and conserve global biological diversity. Significant importance has been placed on new development being undertaken in a sustainable way and the restoration of landscapes damaged by past actions. These genetic relatives of crops also still remain largely uncollected and therefore they are largely unevaluated and unavailable for future breeding programs in agriculture and farming. The conservation of these genetic resources preserves the invaluable raw material needed to develop new varieties of crops in response to changing environments and climate. Qatar is firmly committed to conserving its biodiversity and is party to the Convention on Biological Diversity (CBD) and within this the Global Strategy for Plant Conservation (GSPC) and has developed its own National Biodiversity Strategy and Action Plan (NBSAP). Based on an assessment of the status of biodiversity in the country, Qatar's NBSAP identified a total of 11 strategic goals that identify the most pressing biodiversity issues in Qatar such as protected areas, agrobiodiversity and desertification, scientific research, education and public awareness, invasive alien species etc. To enable Qatar to address both the NBSAP and GSPC targets in relation to plant conservation effectively, fundamental baseline data needs to be obtained. Regional Red Lists following the IUCN Categories and Criteria are an invaluable tool to assess the risk of extinction to species within a country, informing national and regional conservation planning and directly addresses key objectives of both the GSPC and NBSAP. Many reports suggested the Haloxylon persicum Extinct in Qatar but the current study record the excellent site for distribution of Haloxylon persicum there are more than 50 individuals plant recorded using GPS points and satellites map. The distributions maps were prepared. The current research collected seeds, herbarium samples, and DNA samples and their conserved in Qatar gene bank and herbarium.
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Analysis of steam reforming of methane integrated with solar central receiver system
Authors: Haider Ali, Furqan Tahir, Maimoon Atif and Ahmer AB BalochSteam reforming is used for the production of hydrogen or other useful products from hydrocarbon fuels such as natural gas. Reforming is the process in which steam at high temperature reacts with the fossil fuel to form Syngas (CO+H2). The steam methane reformer is widely used in industry for the production of hydrogen. It has the advantage that the energy released from the combustion of hydrogen is almost four times as the energy released from the combustion of methane. In the present study, modeling and analysis of the steam methane reformer is carried out while utilizing the energy via solar tower. In the conventional modeling systems, solar based steam reforming is studied only for a single point in time and the dynamic fluctuations in the solar energy is not taken into account. Therefore, the performance metrics calculated are not necessarily representative of the actual performance of the solar reforming cycle since the performance will obviously be effected by the amount of solar input. In the work, herein, a solar steam reformer is modeled by considering the real-time data for Direct Normal Incident (DNI) irradiation for the city of Doha. As very high temperature is required for reforming, a solar central receiver tower is incorporated which can achieve high temperatures as much as 1300°C. The solar steam reformer is integrated into a solar receiver tower, surrounded by a field of heliostats, such that the solar is directly irradiating the solar reformer. The steam reformer and solar receiver tower is modeled and in-house code on Engineering Equation Solver (EES) software is written for performing the simulations. The system is analyze based on an annual performance so that the fluctuation of solar supply is taken into account with the cycle performance. The performance of steam methane reformer is studied for three representative days of the year that is 29th April, 15th May and 11th August. The performance characteristics of the steam methane reformer is analyzed in terms of methane conversion (Methane Conversion = (xCO+ xCO2)/(xCO+ xCO2+xCH4), where x is the molar concentration) and molar concentration, while incorporating the solar energy data. For 29th April, the peak incident energy is observed at around 1300 hours and the maximum methane conversion (Methane Conversion = 1) takes place at same time due to high solar irradiation. As for the molar concentration of different species, a maximum hydrogen presence in the peak solar irradiance, and the minimum amount of steam and methane is observed. CO presence tends to increase as well, at solar peak hours whereas the CO2 presence does not vary much and almost remains constant most of the time. Similar trends is observed for 15th May while as for 11th August due to no overcasting and continuous solar irradiance, a smooth trend of solar irradiance and consequently a smooth trend of methane conversion and molar concentrations is observed. The steam methane reformer with the solar receiver tower is effectively converting the methane during the solar hours of day. The study provides information about the performance characteristics of the steam methane reformer.
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Electrocatalytic properties of Pt nanoparticles grown on MXene surface
By Peter KasakElectrocatalytic properties of Pt nanoparticles grown on MXene surface Sifani Zavahira, Jaroslav Filipb, Khaled A. Mahmoudc, Jan Tkacd Peter Kasaka,* a Center for Advanced Materials, Qatar University, P.O. Box 2713 Doha, Qatar bDepartment of Environmental Protection Engineering, Faculty of Technology, Tomas Bata University in Zlin, Vavreckova 275, 76001 Zlín, Czech Republic c Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University (HBKU), P.O. Box 5825, Doha, Qatar d Slovak Academy of Sciences, Institute of Chemistry, Department of Glycobiotechnology, Dubravska cesta 9, Bratislava, SK-84538; It is well known that modification of nanoparticles (NPs) allow precise tailoring of their physical and/or chemical properties. MXenes (Ti3C2TX) are 2D nanomaterials with a unique layered structure, hence are frequently studied in energy transformation and storage applications, especially for supercapacitor development. Metal (Au, Ag, Pd, Pt, Co..) and metal oxide (Mn3O4) modified MXenes, have shown significant increase in their catalytic properties compared to the pristine material, while MXene specifically contributing to the stability of the overall material. In this regard, we hypothesised that using MXene as the support material for Pt NPs will enhance the electrocatalytic water splitting efficiency of Pt catalyst, and this will allow us to use a low weight percentage of the otherwise expensive Pt. Hydrogen generation from water splitting produces clean energy, but the high overpotential hinder the rate of hydrogen evolution reaction (HER). Pt being the most efficient catalyst studied to date that can lower the overpotential of this demanding reaction, it is important to find avenues to minimize the amount of Pt used. In this study two Pt NP on MXene were prepared according to two different synthetic protocols. In the first approach (in-situ) Pt NPs were reduced from a Pt salt solution, and this resulted in partial oxidation of MXene layer in the vicinity of Pt4+ ions. Secondly, two catalysts were synthesised with the aid of NaBH4, external reducing agent for structure and activity comparison reasons. Different times of reaction in combination with loading of 5 % and 25 % of Pt in feed were chosen to further investigate the influence of the preparation conditions on the final NPs. Characterization by XRD, SEM, EDX and XPS revealed substantial differences in structure and composition of Pt/MXene nanohybrids synthesised in-situ and with reducing agent. Pt NPs prepared by reducing agent stacked into clusters and the initial Ti3C2TX MXene remained relatively unchanged after the Pt NP synthesis. Whereas, without NaBH4 the Pt precursor was more intensely reduced by the initial MXene particles, this in turn changed MXene NP structure. It was found that this method provided a nanohybrid with a higher overall concentration of Pt and the observed Pt NPs were assembled into larger clusters. HER was tested using cyclic voltammetry performed in a deaerated 100 mM H2SO4 acid solution. Significant boost in the HER rate was observed after modification of MXene with Pt NPs compared to that of pristine MXene (about 1 mA cm-2) irrespective of the synthetic protocol. Maximum current densities up to 61.4 ± 1.7 and 61.9 ± 9.9 mA cm-2 was achieved. This significant increase in current generation was accompanied with a shift of reaction onset potential. Catalytic performance of Pt NPs was tremendously enhanced in the Pt/MXene nanohybrids, thus these nanohybrides become attractive as HER electrocatalyst. Acknowledgements This contribution was supported by Qatar University Grant QUUG-CAM-2017-1. This work was made possible by NPRP grant No.: 6 - 381 - 1 – 078 and 9 - 219 - 2 - 105 from the Qatar National Research Fund (A Member of The Qatar Foundation).The statements made herein are solely the responsibility of the authors.
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Production of biolubricant from renewable feedstocks from Qatar
Due to increase in environmental pollution and decline in petroleum reserves, there is an increase in the demands of developing alternative renewable bio-based products. Petroleum and lubricant manufacturing companies are searching for alternative renewable bio-based products since environmental protecting agencies, all over the world, are putting stringent environmental regulation in practice. Especially, there is a lot of ongoing research to find an alternative and renewable fuels and lubricants. One such alternative for mineral oil based lubricants are biolubricants as they have minimal impact on the environment and human health; furthermore, they have lesser toxicity, excellent lubricating properties, and a higher biodegradability index. Recent research is primarily focused on the synthesis of biolubricants from vegetable oils or animal fats either by chemically modifying the structure of oil or by blending of additives. The aim of this study was to develop biolubricants from renewable feedstocks, found in Qatar, by blending a viscosity modifier additive to meet the existing lubricant standard specifications. We selected 3 renewable feedstocks from Qatar: (i) Waste cooking oil, (ii) Jojoba seeds, and (iii) Waste date seeds. Unlike waste cooking oil and date seeds, jojoba oilseeds need to be collected from the plant. Jojoba plants can be irrigated with brackish water and can be grown in arid region. Oil-rich jojoba seed, therefore, can be considered as the base oil for biolubricants. Waste cooking oil was procured from a local restaurant in Doha, Qatar. Both the Jojoba seeds and the waste date seeds were collected from the Qatar University Biology farm in Zubarah. Initially, the seeds were sun-dried and grounded using a kitchen grinder. Next, oil from jojoba seeds and waste date seeds was extracted using a soxhlet extractor; hexane was used as extraction solvent. Soxhlet extractor was operated for 8 hrs to extract oil from jojoba seeds and waste date seeds. Oil yields from jojoba seeds and waste date seeds were found to be 55% and 10.2% (wt/wt basis) respectively. Waste cooking oil (WCO), jojoba oil (JO) and waste date seed oil (WDSO) were further blended with a viscosity modifier additive, i.e., ethylene vinyl acetate (EVA) in concentrations of 2%, 3% and 4% to formulate biolubricants from all three vegetable oil feedstocks. Addition of viscosity modifier-Ethylene vinyl acetate to WCO, jojoba oil and waste date seed oil increased the kinematic viscosities to maximum values for WCO from 70 mm2/s to 197 mm2/s at 30°C; similarly for jojoba oil it increased 27 mm2/s to 154 mm2/s at 30°C for Waste date seed oil it increased from 29 mm2/s to 160 mm2/s at 30°C. Viscosity for commercial oil (Mobil 20W40 Engine oil) was 190 mm2/s at 30°C. Viscosity index for all biolubricant formulations was calculated and it was found to be above 180. Thermogravimetric analysis of biolubricants revealed that formulated biolubricants were thermally more stable in order of WCO>DSO>JO>CO (Commercial oil). Biodegradability index was calculated BOD/COD ratio it was found to greater than 0.5. In this study, we found that biolubricants formulated from waste cooking oil, jojoba oil, waste date seed oil using viscosity modifier additive and all these biolubricants exhibited increased viscosity, higher viscosity index, better thermal stability and high biodegradability when compared with conventional mineral oil-based lubricant.
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تحسين كفاءة الطاقة للاجهزة المنزلية كثيفة الاستهلاك
More Lessنظرا لزيادة الاستثمارات و التطور الصناعي والتكنولوجي في عصرنا الحديث فقد ازداد الطلب على الطاقة الكهربائية لذا تقوم دول العالم سنويا بإنشاء العديد من محطات إنتاج الطاقة الكهربائية مما يؤدي بدوره الى زيادة الطلب على الوقود المستخدم لتشغيل محطات إنتاج الطاقة الكهربائية وهو ما يؤثر سلبا على صحة الأنسان والحيوان نتيجة انبعاث غاز ثاني اكسيد الكربون و الغازات الضارة الأخرى الملوثة البيئة والتي تعد أحد أكبر أسباب التغيرات المناخية والاحتباس الحراري. وتعتبر كفاءة الطاقة من أهم التحديات التقنية في عصرنا الحديث نظرًا لارتفاع تكاليف إنشاء محطات الطاقة الكهربية وانتاج الطاقة حتى تصل للمستهلك والذي يتحمل تكلفة انتاج الطاقة على عاتقه، لذا فقد اتجه العالم بأثره في البداية إلى استخدام مصادر الطاقة المتجددة و لكنها لم تلبي كمية الطلب المتنامي على الطاقة بالإضافة إلى ارتفاع تكاليف انتاج الطاقة من بعض المصادر المتجددة للطاقة مثل الطاقة الشمسية وطاقة الرياح وندرة أوعدم وجود مصادر الطاقة المتجددة في بعض البلا بالإضافة إلى أن مصادر الطاقة المتجددة لا تلبي إلا قدر بسيط من إحتياج الطاقة الكهربائية. وحديثا تم التوجه وبقوة إلى تحسين كفاءة الطاقة للأجهزة الكهربائية المنزلية كثيفة الاستهلاك والتي تستهلك قدر كبير من الطاقة يذهب جزء كبير منها هدرا بسبب عدم كفاءة هذه الأجهزة و عدم توفيرها للطاقة حيث تفقد حوالي ٩٠ % من الطاقة المستهلكة بواسطة لمبات التنجستين في صورة حرارة ولا يستفاد منها كضوء (الوظيفة الرئيسية للمبة) بل يتم المعاناة بعد ذلك من التخلص من تلك الحرارة عن طريق استهلاك قدر اكبر من الطاقة عن طريق المكيفات مما يتسبب في مضاعفة الاستهلاك. ومع التطور الكبير في أجهزة قياس الطاقة الكهربائية و ما مكنته من القدرة على جمع البيانات من الشبكة الكهربائية و قيمة الاستهلاك في جميع القطاعات سواء التجارية و الصناعية و المنزلية بل و تسجيل جميع العناصر المتعلقة بالاستهلاك للطاقة الكهربائية كالقيمة الفعلية للاستهلاك و معامل القدرة الكهربائية و الطاقة الغير فعالة و الحمال القصوى و فترات الذروة و القدرة على تحليل تلك البيانات بصورة سهلة جعلت من اليسير تحديد كيفية خفض الاستهلاك دون الحاجة انشاء محطات طاقة كهربائية جديدة أو صرف مبالغ كبيرة على صيانة المحطات الموجودة بالفعل. لذا فان البحث في تحسين كفاءة الطاقة للأجهزة المنزلية الكهربائية كثيفة الاستهلاك و انتاج أجهزة كهربائية منزلية و غير منزلية ذات كفاءة طاقة عالية قد يكون محور ارتكاز للعديد من العلماء و الباحثين و دعمت ذلك العديد من حكومات الدول المتقدمة لما له من مردود اقتصادي و بيئي حيث يوفر ملايين الدولارات سواء عن طريق خفض الانتاج و عدم الحاجة لبناء المزيد من محطات توليد الطاقة الكهربائية أو في علاج تأثيرات انبعاثات الغازات مثل غاز ثاني أكسيد الكربون وغيرها من الغازات الضارة و التي لها العديد من الأثار السلبية على البيئة وصحة الإنسان. يساهم الاستثمار في تحسين كفاءة الطاقة للأجهزة المنزلية في تحسين الأقتصاد عن طريق تشجيع الابتكار وخلق فرص عمل للبحث في مجال تحسين كفاءة الطاقة و الحفاظ على موارد الدول من الوقود كما تساهم في تعزيز استقلالية الدول, مما يسهم في الحفاظ على الطاقة إلى جانب تحقيق رضا المستهلكين من خلال توفير منتجات عالية الجودة و موفرة للطاقة و حماية البيئة من أضرار الانبعاثات الكربونية الضارة و تجنيب الحكومات إنشاء المزيد من محطات انتاج الطاقة الكهربائية التي تكلف مبالغ باهظة.
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