Qatar Foundation Annual Research Forum Volume 2013 Issue 1
- تاريخ المؤتمر: 24-25 Nov 2013
- الموقع: Qatar National Convention Center (QNCC), Doha, Qatar
- رقم المجلد: 2013
- المنشور: ٢٠ نوفمبر ٢٠١٣
361 - 380 of 541 نتائج
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Study Of Hotspot Of Pv Modules In Flammable Dust Application Environment
المؤلفون: Anbu Vendan D. PandianBackground Hotspot over the surface of the Photo Voltaic (PV) Modules due to partial shading through dust deposition can cause a p-n junction breakdown leading to temperature rise over the surface of the modules. When the PV module operating current exceeds the reduced short circuit current(Isc) of the shaded cell, it cannot produce energy, rather starts to consume power from the other PV cells connected in series. Researchers measured hotspot temperature rise in the range of 150~200Deg.C due to partial shading or illumination distribution imbalance. Also the intensity of rise can reach to the tune of +300Deg.C, when hotspot occurs due to a crack / damage on cell. Level of temperature rise depending on numerous factors such as number of PV cells connected in series to shaded cell, Open Circuit Voltage (Voc) of the PV cell, shunt resistance, band gap of the PV cell material and location of shade etc. Installation of grid connected PV solar farms adjacent to flammable dust environment can deposit over the PV modules creating partial shading leading to rise in surface temperature. Auto Ignition Temperature (AIT) of many of the flammable / explosive substances are well classified and above + 85Deg.C can become a source of ignition. By-pass diodes are employed to minimize or prevent the effect of hotspot on PV cell by forward biasing the diode during faulty conditions. Normal design in commercial PV modules consider to add a by-pass diode for a set of 15~18 PV cells. There are characteristics mismatch between the PV cells and by-pass diode hence prevention of hotspot is not ensured in total in the event of diode failure. Encapsulated PV module can withstand localized temperature to the tune of +95~150Deg.C depending on the material, the temperature rise due to hotspot can rise above these limits. Methods: Flammable dust is a mixture of lowest AIT (+102Deg.C) substance Carbon Disulfide(CS2) liquid with ash and saw dust. Partial shading of PV modules by the flammable dust mixture for the test is to select cell current coincides as closely as possible with module Isc. Objectives: The main objective of this research paper is to study and evaluate the effect of hotspot phenomena of the PV Modules in flammable dust environment with a focus on fire safety. Results & Conclusions: Mono crystalline and polycrystalline PV modules with varying voltage levels and power output are setup for the experimental verification. Flammable dust mixture for shading is prepared for the experimentation with CS2, ash and saw dust materials in equal proportion. Lower temperature rise PV module is more suited for a flammable dust environment and this study is aimed to identify the material. Key outcome this research may recommend for an application specific PV module is recommended with following design configurations for use in flammable atmosphere, 1. By-pass diode across 3 ~ 6 PV cells thereby reducing the power to dissipate across the shaded cell. 2. Materials of PV cell with lower Voc or band-gap engineered semiconducting material to reduce the effect of hotspot.
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Sustainability Assessment Of Energy,Water And Food Nexus In The Arabian Peninsula
المؤلفون: Tareq Al-AnsariThere is a growing momentum to analyse the broader interdependencies of the energy, water and food systems rather than evaluating them in isolation. For instance, it is impossible to consider a food system without evaluating its respective agriculture, water and energy characteristics using a suitable sustainability assessment methodology. The objective of this paper is to present the sustainability assessment model under development by the authors, which integrates the energy, water and food systems in one resource model. The integrated nexus tool is being designed to estimate the performance of the nexus at appropriate scale and resolution by identifying and quantifying the impact of given food production scenarios on terrestrial and marine eco-systems. Furthermore, the development of an integrated food system is key to the identification of the processes with the largest environment footprint. Life cycle assessment (LCA) is used to prepare detailed models of the sub-system components, determine the linkages between the different nexus constituents and evaluate impacts to the natural environment. The model developed considers the environmental impacts of selected processes within the food system with a special focus in regions of the world where water scarcity is a significant concern, such as Qatar. The nexus elements are described by sub-systems which are modelled using a combination of mass balance calculations, thermodynamic estimates and emission factors derived from literature and real plant data. The food sub-system includes the production and application of fertilizers and emissions from certain agriculture practices such as the raising of livestock. The water sub-systems include the production of water using desalination processes such as Reverse Osmosis and Multi-Stage flash and its distribution to the farm. The energy sub-systems consider both fossil fuel and renewable energy. Environmental emissions are calculated for a food production scenario in Qatar. This involves a crop production profile and corresponding land, water, energy and fertilizer requirements which will serve as inputs to the sub-system models. The outputs of the model are assigned into their respective LCA impact categories. Furthermore, desalination brine discharge is also considered for the aquatic-eco toxicity impact category. Within the sub-systems considered, it is shown the food sub-system produces the largest emissions, followed by fossil fuel powered desalination for irrigation. These emissions in addition the natural gas consumption can be significantly reduced if renewable energy in the form of PV systems are used, with however a significant land footprint. Furthermore, the available simulation tools, which consider the impact of desalination on the salinity of the wider Arabian Gulf, were critically evaluated with respect to their physical significance. When using the projection tool, it was found that Qatar’s food system contribution would represent approximately 0.5% of the total calculated salinity increase. However, evaluating historical data up to 2006, there has been no evidence to support significant differences in salinity conditions within the Arabian Gulf. As such, until a validated and comprehensive predicative model is developed, the models to date cannot provide conclusions on the salinity evolution of the Arabian Gulf and can only serve as comparisons between 2 scenarios.
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Development Of Cao-Based Mixed Oxides As Stable Sorbents For Sorption Enhanced-Chemical Looping Steam Methane Reforming
المؤلفون: Angeliki A LemonidouMethane steam reforming is a carbon-intensive process with high energy requirements. The addition of a CO2 sorbent in the reformer has been proposed as an alternative process to reduce heat demands (since the carbonation reaction is exothermic) and at the same time capture CO2, drive the thermodynamic equilibrium and obtain high-purity hydrogen. In a QNRF funded project, AUTH and TAMUQ are investigating sorption enhanced steam reforming combined with chemical looping. The process is called Sorption Enhanced-Chemical Looping Steam Methane Reforming and in addition to the sorbent, the reformer contains material which serves as an oxygen transfer material (OTM). The basic principle is shown in Fig.1. During the reduction step (reforming), the OTM is reduced by methane into metallic nickel, the active catalyst for endothermic methane reforming, and the reaction proceeds under near autothermal conditions due to heat released by sorbent carbonation. During the regeneration/oxidation step, the reduced OTM is re-oxidized, releasing significant amount of heat which drives the endothermic regeneration of the saturated sorbent. The key for successful commercialization of the process is development of stable sorbents and OTMs that can undergo multiple cycles of reaction/regeneration without deterioration in their performance. Herein, we report results from our studies on development of CaO-based mixed oxides CO2 sorbents. Mixed calcium oxides with alumina, zirconia, magnesia and lanthana were synthesized via the sol-gel autocombustion method using citric acid as a combustion agent. The mixed oxides were prepared with constant 66wt% concentration of free CaO and were characterized by BET and XRD. Results showed that CaO is formed in all cases, accompanied by formation of mixed Ca3Al2O6 and CaZrO3 in Ca-Al and Ca-Zr sorbents, respectively. On the contrary no mixed phase was formed between CaO and Mg or La. The sorption capacity and stability of the sorbents were tested in a TGA instrument (or unit) for 100 consecutive sorption-desorption cycles under 15% CO2 in N2 for 30 minutes at 650°C and 100% N2 for 5 minutes at 850°C. The CO2 capacity of all the synthesized sorbents as a function of a number of cycles is shown in Fig.2. The highest CaO conversion was obtained with Ca-Al (99.8%), followed by Ca-Zr, Ca-Mg and Ca-La. The most stable material proved to be Ca-Zr with only 13.7% loss of capacity after 100 cycles. Ca-Al also had a promising performance with 20.7% loss, while Mg and La both exhibited significant deactivation (i.e. 30% loss in sorption capacity). The two most promising materials (Ca-Al and Ca-Zr) were also synthesized using a different combustion agent, triethanolamine, to investigate the effect of an organic fuel. The use of TEA was beneficial for Ca-Zr,which achieved higher CaO conversion (96.9%) and better stability (13.4% loss), while the opposite trend was observed for Ca-Al. Overall among all investigated CO2-sorbents, Ca-Al and Ca-Zr prepared with both citric acid and triethanolamine as combustion agents, exhibited excellent initial capacity and stability, with a sorption capacity higher than 9 mol CO2/kg of sorbent after 100 sorption-desorption cycles under relatively mild operating conditions.
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Comparative Sedimentology, Geomorphology and Hydrochemistry of Continental and Coastal Sabkha Systems, Qatar
المؤلفون: Sher Mey OoiHolocene sabkhas in the Arabian Gulf are important as analogues to ancient evaporitic hydrocarbon reservoirs. Sabkha, an Arabic term for salt flat, refers to marine coastal sediments which have been modified by precipitation of evaporitic minerals from groundwaters. Extensive and detailed geomorphological and sedimentological characterization of depositional environments in Qatar provides a framework for understanding hydrological and geochemical processes controlling the origins of evaporites, their spatial distribution and likely evolution of burial diagenesis through time. A range of hydrological models have been proposed to account for the sources of solutes forming the evaporites in different sabkhas, including discharge of continental groundwaters, evaporative pumping of seawater, seawater flooding and free convection. Comparison of two hydrological end-member regimes in Qatar, a coastal sabkha in continuity with marine water (Mesaieed) and a continental sabkha within a closed basin (Dukhan), offers new insights into the variability and complexity of sabkha hydrological systems. Mesaieed sabkha, located in the southeast of Qatar is part of a prograding coastal plain and consists of an onlap wedge of Holocene sediments with a basal coarse transgressive lag, overlying Eocene bedrock. The Holocene wedge is in hydraulic continuity with both marine and continental waters, although tidal head differences are observed only a short distance inland from the coast. Dukhan, a large inland sabkha in the Arabian Gulf, has formed in a syncline between the Qatar arch and the Dukhan anticline, which separate it from the west coast. The sabkha surface is below sea level, separated from a marine embayment to the north by an Eocene sill of unknown transmissibility. Sea-level reconstructions reveal marine communication in the Early Holocene, suggesting the basin was flooded during an earlier highstand, with evaporitic lakes or salinas developed within restricted areas. Gypsum is the most common diagenetic evaporite mineral in both sabkhas and is pervasive above and below the water table, with minor calcite, dolomite, anhydrite and halite. In Mesaieed such cementation is extensive in the proximal sabkha (in sediments dated c. 6000 yr BP), whilst in the central part (c. 4000 yr BP) gypsum is restricted to surface crusts and water table cements, and is largely absent in the distal (coastal) sabkha (≤ 2000 yr BP). In Dukhan gypsum occurs as surface crusts, detrital grains and coarse crystal mushes, formed in the sediment as well as in standing water. Halite and anhydrite occur near the surface. Geochemical studies suggest that evaporites are forming today. Both sabkhas act as sinks for brackish groundwater from the underlying Eocene aquifers of Qatar. Evaporative concentration of discharging groundwaters in the sabkha at and above the shallow water table generates dense fluids which reflux into the underlying Eocene, increasing solute concentration with distance from the Eocene/Holocene contact. In Mesaieed, studies indicate rare episodic inundation of the sabkha surface and subsurface intrusion of seawater may be significant in the distal part of the system and could explain the paucity of gypsum cementation.
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Nanosorbents For The Selective Removal Of Boron From Seawater
المؤلفون: Khaled MahmoudThe rejection efficiency of boron by RO membranes is poor, especially when a large proportion of boron in feedwater exists as uncharged boric acid which can diffuse through most of the available RO membranes.1,2 Among the methods suggested for boron removal from water and wastewater, adsorption is a very useful and economical technique. Magnetic adsorbents containing chelating precursors that are selective for boron have been used as a smart, fast and simple method for the separation and pre-concentration of boron3. After adsorption, the adsorbents can be isolated from the medium by simple magnetic separation. Here, we present novel magnetic nanocomposites for the selective removal of boron from seawater. The nanocomposites have been synthesized and fully characterized using scanning electron microscopy (SEM), tunneling electron microscopy (TEM), Fourier transformed infrared (FTIR) and powder x-rat diffraction (PXRD). This technology provides a simple method for the adsorption of boron and separation of magnetic nanoparticles from a solution using an easy magnetic procedure. The effect of different nanosorbents, sorbent amount and pH on the sorption of boron was studied. The magnetic sorbent that provided the highest boron sorption efficiency was used for the subsequent experiments investigating the most effective magnetic sorbent amount and pH for the sorption of boron. Experimental results indicate that boron sorption increases with increasing sorbent dosage up to a sorbent amount of approximately 0.6 g, after which the difference in removal efficiency was found to be negligible. The effect of pH on boron removal efficiency using the nanosorbents was studied at initial boron concentrations of 4-5 ppm, amounts commonly found in seawater. The sorption of boron was found to be highest at a pH range of 7-7.5 with a sorption efficiency of 77.6 ± 1%.
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Different Kinetic Degradation Of Methyl Orange By Nanostructured Titania: Titania Nanotube, Titania Nanofiber, And Titania Nanoparticle
المؤلفون: Dong Suk HanTiO2 is a semiconductor with photo-catalytic properties and is being thoroughly investigated for its use in the degradation of harmful environmental pollutants using photo-catalytic reactions. The effects of TiO2 nanoparticles and different structured TiO2 electrodes on methyl orange degradation using sunlight have been investigated. Titania Nanotube (TNT) and Titania Nanofiber (TNF) were obtained through anodic oxidation of pure titanium sheet and titania nanoparticle was commercially available. Nanostructured Titania was doped with palladium and Methyl Orange, a harmful environmental pollutant, was degraded using palladium doped nanostructured titania. The kinetic degradation was observed using UV-Vis spectroscopy. Titania Nanotube degraded the pollutant faster than titania nanofiber because of the larger surface area provided by tubes. Titania nanoparticle being in the powder form was the most effective in degrading methyl orange pollutant because of the very large surface area providing higher catalytic capability.
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Isolation And Screening Of Hydrocarbon Degrading Bacterial Strains For Bioremediation Of Petroleum Pollution In Qatar
المؤلفون: Zulfa Al DisiPollution, due to activities related to the oil industry, represents a serious threat to the natural environment. The application of biotechnological methods provides much safer and sustainable alternatives for bioremediation of polluted areas, using microorganisms. Several techniques for the isolation of hydrocarbon degrading bacteria have been investigated and published worldwide. A wide range of biological activities was shown. However, local hydrocarbon degrading strains and the factors affecting bacterial and strains variability were not studied deeply. In this study, we showed that the isolation and screening strategy affected a lot, the selection of the strains. We combined the bacterial tolerance to hydrocarbon toxicity, assessed by the growth parameters, and the bacterial degradative activities, assessed by the degradation of a wide range of petroleum hydrocarbons via gas chromatography analysis. The main investigations and findings of the present work are: A collection of 39 bacterial isolates from Qatari polluted soil was set up and a new isolation and screening program was proposed. The growth conditions and the activity of pre-selected strains Shift of the activity of the selected strains from a range of hydrocarbons to another by the effect of the nitrogen source, C/N ratio and organic nitrogen source 70% hydrocarbon removal, achieved with several strains in 2 weeks. Amongst 12 identified isolates and by molecular ribotyping-DNA sequencing, 3 strains of Pseudomonas genus were isolated from a polluted soil in Qatar, are available for bioremediation of highly polluted soils, tolerating high toxicity and may be adapted to a variety of low or high molecular weight hydrocarbons.
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Performance Analysis Of Empty Container Logistics At Qatalum Smelter
المؤلفون: Fatih MutluThis project aims at identifying and validating the performance measurements of container logistics at Qatalum Smelter. The project investigates two different cases that Qatalum has implemented to manage the empty container logistics using simulation. The first case is to keep a limited empty container buffer; and the second case is to provide empty containers in a just-in-time fashion. Accordingly, a field research was conducted at Qatalum to collect required data. Quantitative and informative data were collected though meetings, on-site observations, and time and motion measurements to develop spaghetti diagrams that show all possible flows and flow charts of container logistics in order to develop the simulation models. Both situations were simulated using Arena software. Optimal buffer size of empty containers inside the cast house was determined, in which different empty containers buffer sizes were tried to choose the optimum buffer size. The vehicle fleet utilization in both cases was determined and scenario testing was implemented, in which the effect of adding additional resources was observed. The results show that the optimal buffer size of empty containers inside the cast house is 14 containers. The vehicle fleet utilization in the current case is less than its utilization in sand case and the most utilized vehicles in both cases are trucks and the container mover. The impact of additional resources is also studied via simulation.
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Migration Of Phthalates Into Bottled Water
المؤلفون: Noof AlqassmiMigration of phthalates into bottled water
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Synthesis, Characterization, And Application Of Pyrite For Removal Of Mercury
المؤلفون: Dong Suk HanSynthesis, Characterization, and Application of Pyrite for Removal of Mercury
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Reactive Nanoparticle-Supported Dead-End Flow Ultrafiltration For Removal Of Mercury From Water: Effect Of Solution Composition
المؤلفون: Dong Suk HanReactive Nanoparticle-Supported Dead-End Flow Ultrafiltration for Removal of Mercury from Water: Effect of Solution Composition
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Modeling A Seawater Flash Distillation Process With The Q-Electrolattice Equation Of State
المؤلفون: Faiha Al-QahtaniModeling a Seawater Flash Distillation Process with the Q-Electrolattice Equation of State
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Effect Of Lspr And Pspr Coupling In Different Patterns Of Silver And Gold
المؤلفون: Anchu AshokAnchu Ashok*, Arya Arackal, George Jacob, Gargi Raina Centre for Nanotechnology Research, VIT University, Vellore, India - 632014 * [email protected] Keywords: Surface Plasmon, Localization, Propagating surface plasmon, Coupling. Surface Plasmons (SPs) are collective electron oscillations at metal dielectric interface. They are often categorized into localized surface plasmon resonance and propagating surface plasmon resonance (PSPR). LSPR are non propagating electromagnetic waves and PSPR are propagating. In this work, we have carried out a study of Electric Field Intensity variation for different isolated and array structures of Au and Ag for corresponding plasmonic wavelength. Double plasmon resonance peak are observed, which is the combined effect of localized surface plasmonic resonance (LSPR) and propagating surface plasmonic resonance (PSPR). Shape, size and thickness of the structures affect Localized surface plasmonic resonance while as propagating surface plasmonic resonance (PSPR) is dependent on the 1D and 2D arrangements of the patterns. Depending on the sharp and confined corners, density of the hot spot in structures changes. Hence, triangular structure gives more excitation when compared with circle, square and ellipse. This work followed triangular patterns to find the coupling effect of LSPR and PSPR depend on the arrangement of patterns. Incident TM polarized plane wave of wavelength from 300 nm to 1000 nm with electric field intensity 1V/m was given for finding the enhancement of electric field in the patterns. Sharper the corners, more is the electric field enhancement. Another important factor affecting the enhancement of electric field is the grating period. If distance of two adjacent corners decreases, the coupling between the localized surface plasmons increases. This increase in coupling leads to the propagating electromagnetic wave called propagating surface plasmons (PSPs). This coupling distance depends on the propagation length of electric field from one structure to another. If the second structure is placed at a distance less than that of the propagation length there is an effective coupling of the electric field from one structure to another. This work discusses about simulation of electric field intensity for three types of patterns with the variation on their period and confinement employing Finite Element Method (FEM). Double resonance peak are noticed in all structures is due to the coupling effect of field from one structure to another and there is change in field enhancement and resonance wavelength with different patterns. Resonance wavelength due to the PSPR is at longer range and that of LSPR is at shorter range. Propagating surface plasmon resonance wavelength is same for a particular structure irrespective of number of structures in the array. Spectral separation between the LPSR peak and PSPR peak can be modified by changing the period and confinement in the structures. Silver patterns show better enhancement than gold patterns. The enhancement of Gold patterns is in near IR range and that of Silver is in visible range. Combined effect of this LSPR and PSPR give drastic field enhancement which makes these patterns as good substrate candidate for Surface Enhanced Raman Spectroscopy and biosensors.
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Spatial And Temporal Distribution Of Heavy Metals In Marine Sediment Along The Doha Bay
المؤلفون: Hajer Al-NaimiAbstract Concentrations of twenty five heavy metals (Ag, Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn, and Hg) in surface sediment from ten transects each with five stations were studied. The sediment samples were collected in May and December 2012 in order to examine the spatial and temporal variation and investigate the pollution sources. Significant differences were observed in metal concentrations between the sampling locations and durations. Higher concentrations were observed in areas where there are a lot of anthropological activities. The distribution of selected metals were presented in contour maps showing the variation between the two periods. Moreover, it was observed that December 2012 sampling was significantly higher than May 2012. In order to further study particle size effect on metals uptake, two different grinding times were administered on four randomly selected samples and the results showed no significant difference on the analysis in the ICP-OES instrument. The overall results of metal analyses were within the international standards criteria and the results were comparable to the previous studies conducted around Qatar. A monitoring approach is recommended for the sediment quality assessment. Additional examinations were conducted using contour maps that show the distributions of the metals around Doha Bay during May and December 2012.
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A High-Power Photovoltaic Power System based on Quasi-Z-Source Cascade Multilevel Inverter
المؤلفون: Yushan LiuI. INTRODUCTION The utility-scale Photovoltaic (PV) system experienced a tremendous growth to satisfy the fast increase of world's power demand. Nowadays, focus has been placed on innovative and cheap inverter solutions and system configurations. Among them, The Cascaded Multi-level Inverter (CMI) structure is more preferable to reach utility-scale power ratings and medium-voltage levels due to transformer-less, small size, high efficiency, high power density, and low cost. However, due to lack of boost function, the traditional CMI will lead to overrating the inverter by a factor of two to cope with wide (1:2) PV voltage variations. The recently proposed quasi-Z-source CMI (qZS-CMI) structure provides attracting improvement by combing the quasi-Z-source network into the traditional CMI. In addition to the advantages of traditional CMI, the qZS-CMI provides buck/boost function in a single-stage inverter topology, the independent dc-link voltage balance, and the one-third module reduction. All of those will bring positive effects on the system volume, efficiency, and cost. Contributions of this paper are proposing a high-power PV system based on qZS-CMI, which is 1-MW power and 11-kV voltage with 16 cascaded quasi-Z-source H-Bridge inverter (qZS-HBI) modules per phase. In this way, the high-power system can be fulfilled by low-power-low-frequency devices, aiming at the proposed PV system of low cost, high efficiency and reliability, and high performance-cost ratio, thus to improve the scientific and economic developments of Qatar. II. METHODS AND RESULTS The proposed system was simulated in MATLAB / Simulink by: 1) Sixteen cascaded quasi-Z-source H-Bridge inverter modules per phase. 2) Each qZS-HBI is fed by separate PV panels. 3) The phase-shifted sinewave pulsewidth modulation is applied to synthesize the multilevel voltage waveform. 4) Next step is to design the control scheme of the system with maximum power point tracking, grid-tie injection, novel modulation, etc.. ACKNOWLEDGEMENT This work was supported by NPRP-EP No. X - 033 - 2 - 007 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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Household Laundry Wastewater Reuse For Food Production
المؤلفون: Hazim QiblaweyLaundering processes use significant amounts of water, including water-washing processes and dual-phase washing. These processes perform a separation process in which soil and stains are removed from a textile substrate. The most important ingredients of laundry detergents are bleach, water softeners and surfactants. Using laundry effluent into gardens and lawns was shown to be technically possible without treatment in many areas in Australia and USA. Among the various environmental concerns facing Qatar, the most pressing is linked to the country's most acute water scarcity according to Qatar's National Development Strategy 2011-2016 (QNDPS). Farming in Qatar continue to make heavy demands on Qatar's precious water resources. Laundry wastewater reuse for food production could make a significant contribution to redirecting Qatar's precious natural resources to higher value uses. Related issues like food safety, hygienic issues and possible ground water contaminations should be investigated in parallel with any step to be taken in this regard. The current study aims to evaluate the reuse of laundry wastewater from Qatari household in irrigating edible vegetables (Fig. 1). The wastewater is fully characterized. The analysis includes pH, EC (conductivity) and COD (chemical oxygen demand). In addition Total cations (Na, K, Ca, and Mg), total anions (HCO3, SO4, and Cl), and trace elements including Mn, Cu, Pb, Zn, Co, Fe, and Cd will be found. The same characterization is followed for the different parts of the plants; leaves, roots, stem, fruits and the planting soil itself. Irrigating with tap water is used as reference (Fig. 2). Plants and soil irrigated with tap water is subjected to the same chemical analysis as the wastewater. The project will shed light on the possibility for the reuse of this valuable wastewater stream. The study will compare the results with international standards and a statements about the suitability of using laundry greywater for irrigation will be withdrawn. The research will define the limitations and put recommendations and suggestions for further implementation. The results from this study are expected to support people working in water and safe food sector in Qatar.
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Unsignalized Intersection: Assessment, Forecast And Performance Measures
المؤلفون: Roba SalemVehicles at Qatar university road networks are subject to pass through multiple roundabouts and intersections in order to reach their destination. Since the traffic volume is relatively low, unsignalized controlled intersections are used to regulate the flow of vehicles (sign-controlled) .T shaped intersections and multiple lane roundabouts are utilized throughout Qatar University closed loop system. This study has been conducted to measure the current performance of some unsignalized intersections at Qatar University roads. Two roundabouts and one TWSC intersection were selected for the study. The methods presented in the Highway Capacity Manual (HCM 2000) were employed in this study and were used to compute the various approaches and movements capacities and the related performance measures .e.g. Control Delays (s), Queue lengths (veh ) and Level of service (LOS). To this end we will base our capacity analysis on Gap acceptance method and on simple, empirical, lane-based, regression model for multiple lane roundabouts. Data inputs collected for the selected method involved the critical traffic volumes (veh/hr) which occur in the peak hour .15 peak minute flow rates were recorded to obtain the peak hour flow rates. In addition the methods were used to make future projection of the capacities and the related performance measure based on forecasted demand in 2022. The results show that the current performance of the roundabouts is satisfactory for which the Level of service was graded A for all approaches in the two roundabouts given that the computed delays never exceeds 10 s / vehicle in any approach. The current results for the roundabouts coincide with the actual performance of the intersections where very little delays are encountered while driving and very short queues are formed during the peak hour. Regarding the T intersection the performance of the Left turn of the major street was found satisfactory and was graded A while the performance of the shared lane of the minor road was graded C. Based on forecasting results, the increase in entry and conflicting flow rates have resulted in decreasing the expected capacities of the various approaches on the studied intersections. In general for the roundabouts no significant difference in performance is to be experienced in year 2022 when current demand is expected to experience over 50 % increase and still the performance will be satisfactory. The same conclusion was drawn for the Left turn movement from Major Street that no major difference in performance is projected in future. But this conclusion was not applicable on the shared lane where it was very much affected by the increase in demand and the performance has rapidly dropped from its current level.
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Critical Pitting Temperature Of Ti-6Al-4V Produced With Rapid Prototyping Technology: Electron Beam Melting Machine
المؤلفون: Dana AbdeenCritical Pitting Temperature of Ti-6Al-4V Produced with Rapid Prototyping Technology: Electron Beam Melting Machine Abstract Titanium and its alloys are valuable engineering materials due to their excellent mechanical and physical properties. Comparing to other metallic materials such as stainless steel and Co-Cr alloys; Ti and its alloys are of lighter weight, higher strength-density ratio, superior corrosion resistance in wide range of environments, and better biocompatibility in human body. The most widely used titanium alloy is Ti-6Al-4V. It contains a combination of α stabilizer (Aluminum) and β stabilizer (Vanadium) that gives better microstructure combination, resulting in a good balance of strength, ductility, fracture and fatigue properties. Rapid prototyping technology allows the manufacturing of 3D intricate objects through the layer-by-layer technique. Electron beam melting (EBM) machine utilizes this 3D printing technology to fabricate complex objects using Ti-6Al-4V alloy. EBM machine uses electrons as the energy source to melt layer-by-layer the metallic powder and build the required parts under vacuum pressure of 10-3 mbar and temperature of 690°C. Parts produced with this machine can be used in many applications such as; petrochemical industry, chemical processing, aerospace applications, medical applications, and automotive industry. Due to the unique manufacturing conditions of high temperature, vacuum pressure, and quenching of the molten metal to nearly room temperature in just a few hours; the corrosion behavior of produced part is likely very different from that of traditional wrought alloys. In addition, surface roughness and density of parts out of such machine is different than traditional commercial titanium. Notwithstanding this, EBM machine can work under different sets of processing parameters, which allows a control of part properties. This study measures the critical pitting temperature (CPT) of samples produced under different processing parameters of EBM machine. CPT test was performed to detect the temperature at which the part will start to pit in a 3.5% weight NaCl solution. CPT gives an indication of the ability of the metal to withstand pitting under specified tested condition and specifies the temperature at which pitting of the surface will start. Surface roughness and density were measured as well, and a Minitab software was used to relate these properties to the EBM machine manufacturing parameters in order to optimize the best working parameters that will enhance the quality and increase corrosion resistance of produced parts.
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Isolation, Identification And Characterization Of Soil Borne Fungi From Qu Field 2, Field 3 And Qu Farm
المؤلفون: Meaad Al-JassimMeeaad Y. Al-Jassim1, Noof M. Al-Korbi1, Fatima A. Al-Naemi1 1Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar The mycobiota of soil was investigated in ninety soil samples collected from three different localities in Qatar, biology field2, biology field 3 and University farm. Biology field 2 and biology field 3 are located at longitude and latitude 549350.32 M.E and 2866180 M N 3 549812.00 ME and 2806702.93 M N respectively. Qatar University farm is located in Raodat Al Faras, about 60 km north of Doha (49° 25´ N, 20° 51´ E), 14.1 meters above sea level, with an area of 54.3 ha. Soil samples were collected under Zygophyllum quatarense, which was dominated in biology field 2 and 3 and from rhizosphere of fig, lemon, and date palm trees in QU farm. Twenty nine species of fungi belong to 9 genera were isolated from Biological field 2 and 3 at Qatar University. Whereas 19 fungal species belonging to 10 genera were isolated from QU farm. The distribution of soil borne was affected by the microclimate, physic-chemical propriety of soil and types of vegetation. The genus of highest incidence and their respective numbers of species was, Rhizopus ( 24 %, 3 species) isolated from biology field 2 and 3. The genus of lowest incidence was (Aspergillus (4.5 %, 2 species) islolated from biology field 2 and 3. Whereas, Aspergillus was the most common genera(43.78%, 18 species) isolated from QU farm followed by Rhizopus (13.4 %, 4 species) and Trichoderma (7.7 %, 2 species). Sixteen isolates were shown an antagonistic activity. Alternaria chlamydospora showed highest percentage of antagonistic activity against many species. In contrast, introduction of Rhizopus arrhizus led to approximately 62.5% reduction in Alternaria chlamydospra growth. Moreover, Penicillium griseofulvum inhibited the growth Alternaria chlamydospra by 10%. Keywords: Soil borne fungi, antagonist, microclimate, biological control
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Performance Improvement Of Grid-Interfaced Renewable Energy Sources In Smart Grids During Faults
المؤلفون: Hisham El DeebPerformance improvement of grid-interfaced renewable energy sources in smart grids during faults
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