Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1

In order to ensure long-term sustainability of the reservoir, the gas industry in Qatar is faced with the challenge of reducing the volume of produced and process water (PPW) sent to disposal wells by 50% [1-3]. Recently, Qatargas initiated a project to recycle process water and thus, reduce disposal volumes using commercial advanced water treatment technologies [4]. One emerging technology, “osmotic concentration” (OC) has been identified that offers a low-energy alternative to conventional thermal or membrane volume reduction methods. Osmotic concentration is a membrane filtration process that mimics first step in a forward osmosis (FO) system. It requires a high salinity draw solution (DS) which passes on one side of a semi-permeable FO membrane while the feed passes on the other side. Water from the feed is drawn through the membrane, via natural osmosis, reducing the feed volume and increasing the volume of the draw solution. This paper summarizes the results of bench-scale volume reduction tests with PPW collected from Qatar's North Field operations as the feed and either seawater or the concentrated brine from thermal desalination plants as the draw solution. While in conventional forward osmosis, the draw solution is regenerated, in OC, there is no regeneration of the draw solution. The diluted seawater or brine would be simply discharged to the Arabian Gulf. For future projects/developments, the authors have proposed OC for PPW volume reduction, which can be a cost-efficient alternative to achieve 50% reduction in disposal volumes (Fig. 1). This approach is particularly applicable in Qatar due to close proximity of desalination plants and gas processing facilities. In all membrane processes, the driving force for permeation is pressure. The mechanism by which the pressure is created differentiates various membrane processes: Reverse osmosis: static pressure generated by a pump Membrane distillation: vapor pressure differential due to a difference in temperature Osmotic concentration: osmotic pressure differential due to a difference in salinity. In these examples, the driving force or transmembrane pressure (TMP) can be measured in units of kPa or bar. In reverse osmosis, the TMP ranges from 15 to 60 bar depending on the salinity of the feed. In osmotic concentration, a comparable TMP of 15 to 60 bar is generated simply by high salinity the draw solution, i.e. without any static pressure being required and hence the low energy requirements for OC processes. In addition to significantly lower operating energy requirements [5], an OC process offers the following advantages over reverse osmosis (RO): Lower capital cost because pressure-rated vessels and high pressure pumps are not required [6]; There is strong evidence that FO membranes are less prone to irreversible fouling than RO membranes and foulants can be removed by simple flushing with clean water with no addition of chemicals [7,8]; The water discharged to the Arabian Gulf is of lower salinity and that provides an environmental benefit. The primary disadvantages of OC are that there is no water recovery after the separation process and there is limited experience from full-scale water treatment installations. The main objective of this study was to investigate the feasibility of OC to concentrate PPW from gas operations by 50% using brine from thermal desalination plants as draw solution. The PPW was a combination of gas field produced water extracted from an offshore reservoir and process water from onshore operations. The blending ratio between produced and process water was approximately 1:5. The PPW underwent deoiling, H2S removal and cartridge filtration (2 mm). The detailed composition of PPW and brine from thermal desalination plant are shown in Table 1. During this study, experiments were conducted to evaluate OC performance in treating PPW in the following areas: membrane configuration membrane fouling effect of pretreatment process optimization long-term stability/performance. In all tests, the active layer faced the feed solution (AL-FS mode) since this configuration provides better control of feed-side fouling. Membrane configuration During this project, two membrane configurations were evaluated: Flat sheet (FS) membranes, commercially available [9]Hollow fiber (HF) membranes, Singapore Membrane Technology Centre [10, 11]. The membrane surface areas were 0.014 and 0.0106 m² for the FS and HF modules, respectively. Experiments were conducted using two feed solutions: DI water and PPW. Results showed that the HF membranes had improved performance from both the water flux and reverse solute flux (RSF) perspectives. The HF membrane flux was ≈ 35 to 45% higher for both DI water and PPW (Fig. 2). With PPW as feed at 25?°C, the RSF was measured for both membranes and the results showed that HF membranes exhibited ≤ 3 mmol/m² h RSF for Na⁺ and Cl⁻  while FS membranes showed a RSF of ≈ 20 mmol/m²h for both ions. RSF is highly sensitive to operating temperature. Because HF membranes showed superior performance and there are also commercial advantages (higher packing density, lower fabrication cost), experiments focused on evaluating HF performance in treating PPW. Membrane fouling: To assess if membrane fouling occurred, a benchmark test with DI water as feed solution and 1M NaCl as draw solution at 25?°C was conducted before and after each fouling test. A decline in the benchmark flux after treating PPW would indicate that membrane fouling had occurred. The fouling tests were conducted on two feed streams: synthetic PPW (mimicking only the inorganic content of PPW) and real PPW. During the experiments, the initial volume of PPW was reduced by 50% and the draw solution (DS) was 1M NaCl. The DS concentration, for both benchmark and fouling tests, was maintained constant throughout the experiments by adding concentrated NaCl solution based on conductivity measurements. While the results for synthetic PPW showed that no fouling had occurred, the results showed that PPW could cause fouling on the membrane surface since the benchmark flux decreased from 17.5 to 15 L/m^2?h (Fig. 3). The fouling was attributed to the organics present in the PPW since no flux decline was observed on the when synthetic PPW was used as feed. These results highlighted the need for effective pretreatment to remove organics. Effect of pretreatment: To determine if pretreatment could remove the organics responsible for fouling, a number of methods were screened and ultimately powdered activated carbon (PAC) was selected for pretreatment of the PPW. PAC is widely used for organics removal and previously evaluated for similar applications [12]. Lab results showed that at a dosage of 500 mg/L PAC, the TOC from the PPW was reduced from 132 to 45 mg/L. The PAC dosage was considered very high for a full-scale application and further pretreatment optimization is needed before field implementation. OC performance experiments showed no decline in benchmark flux when the volume of pretreated PPW was reduced by 50% indicating that pretreatment is essential for the successful implementation OC to reduce PPW disposal volumes. Results also showed that the HF membranes have good rejection for organics. For both the treated and untreated PPW, the TOC in the draw solution after OC treatment was below the 1 mg/L detection limit indicating that the membrane rejection of the organics was >99%. Process optimization: Box-Behnken design: The main operating parameters for this application were optimized using a Box-Behnken design (BBD) [13, 14]. BBD is a response surface methodology that explores the effect of different input variables (temperature, draw solution concentration and feed crossflow velocity) on the output response (flux). This statistical tool takes into consideration the combined effects and interdependence of the input variables and significantly reduces the number of tests required as compared to the conventional factorial experimental design. The following parameters and test values were used during the BBD experiments: Temperature: 25, 35 and 45?°C Draw solution concentrations: 40, 55 and 70 g/L NaCl Feed crossflow velocity: 40, 60, 80 cm/s. Results showed that the temperature has the greatest impact on the flux, since it influences the water viscosity. DS concentration directly affects the osmotic pressure, influencing the flux. The feed crossflow velocity did not affect the process performance over the range tested. These results are consistent with authors’ expectations and general published results. Based on the BBD analysis, the optimized process conditions were: 45°C temperature, 70 g/L draw solution concentration and 80 cm/s feed crossflow velocity. Figure 4 shows the comparison of the OC performance, to achieve 50% feed volume reduction, at benchmark (25?°C, 70 cm/s, 58.5 g/L NaCl) and optimized (45?°C, 80 cm/s, 70 g/L NaCl) conditions. Long-term performance and water quality: The elimination of the water recovery step in osmotic concentration makes it an energy efficient process [5]. To confirm if the brine from thermal desalination plants is a suitable DS for the treatment of PPW, a long-term experiment was performed simulating full-scale operation. In earlier experiments, the concentration of the DS was maintained constant, by adding concentrated DS. Since this is not feasible in full-scale applications, a process stability experiment was carried out without controlling the DS's concentration, allowing it to dilute with time as water permeates through the FO membrane. The experiment was conducted using pretreated PPW as feed and brine from thermal desalination plant as DS. The solution temperature was 45?°C since this is the expected temperature of the brine discharged from the desalination plant. The feed and draw solutions crossflow velocities were 80 and 40 cm/s respectively. The test was conducted for 80 hours. The PPW initial volume was 42 L and it was reduced in volume by 50% while the volume of the draw solution, initially 21 L, was increased to 42 L, reducing its salinity by 50%. A relatively stable performance was observed throughout the experiment with a 30% decrease in flux (from 28 to 20 L/m²?h) due to the decrease of the effective osmotic pressure and to the influence of the internal concentration polarization (ICP). After a sharp initial decline in osmotic pressure differential, the decline in flux almost tracked the decline in the osmotic pressure differential (Fig. 5). DI water fluxes during benchmark tests conducted before and after the experiment remained constant at 19.4 L/m²?h indicating that negligible fouling occurred. To evaluate the ability of HF membranes to reject specific contaminants, various water quality analyses were performed. Results showed that HF membranes have high rejection capabilities. The ions with the highest solute fluxes values were sodium and chloride with a RSF of 120 and 91 mmol/(m²?h) respectively at 45?°C (Table 2). Although a small amount of nitrogen passed through the membrane from the PPW to the draw solution, at the levels found (5.8 mg/L), it was below the discharge limits set by the State of Qatar and the European commission (10 mg/L) [15]. The results also showed that the organic carbon present in the PPW was rejected by the membrane and retained in the PPW. A slightly increase in the TOC concentration in the DS was observed and it could be attributed to uncertainties in the analysis since the results were at the low end of the measurement accuracy. Finally, preliminary cost estimates and energy calculations showed that OC is economically feasible to reduce PPW injection volumes from gas fields in an environmentally sustainable manner. The research team is currently evaluating different pilot testing opportunities to further demonstrate the cost-effectiveness of this technology under relevant field conditions.

The Khor Al-Adaid “Inland sea” in Qatar is a unique desert lagoon, located in the South east of Qatar and is characterized by a distinct salinity gradient (ca. 4% halite salt to saturated conditions). In the framework of the QNRF funded NPRP project, researchers from Qatar, Germany and Austria have succeeded to isolate and cultivate a new unicellular eukaryote (protist) from Qatar's unique Inland Sea (Khor Al-Adaid). Initial genetic marker analyses pointed to the novelty of this organisms and morphological characterization confirmed that this isolated organism is not yet known and described from any other place in the world. Even though only 1/50th of a mm in length, this organism may hold secrets worth unlocking: the Qatar's Inland Sea is characterized by extremely high salt concentrations. With the discovery of this new organism from the Inland Sea the team of researchers hold in their hands a valuable unique treasure from Qatar's natural heritage. Future efforts will be to exploit this treasure for its genomic and biotechnological potential. The new species belongs to the genus Euplotes, and is coined the name Euplotes qatarensis nov. spec.

GCC's climate has a high ambient temperatures throughout most of the year, therefore, the air conditioning is not optional or luxury, it is a necessity. Residential sector in those countries represents the largest portion of electricity consumption. According to Qatar National Development Strategy (QNDS) 2011-2016, two-thirds (67 percent) of total residential power consumption in Qatar is due to air conditioning units (AC), Such heavy cooling demand is expected to approximately triple by 2030. Thereby, the fuel needed to power air-conditioning units in the GCC will is expected to 1.5 million barrels of oil per day. Energy efficient system is basically depending on two different categories; technological modification program and behavioral modification program. Both programs are required for energy efficient air conditioner systems. Existing air conditioner systems are based on conventional technological modification systems without considering the behavioral modification program which are impacted by the cost of implementation, impact on running systems as well as providing a fixed step algorithm of closed loop control between utility and residential customer. Therefore, we present a novel embedded real-time, smart, active energy and efficient air conditioning system for minimizing energy consumption, and minimizing energy cost per day while considering residential customer preferences, comfort level in behavioral modification program and health aspect, which provides opportunity for residential customer to reduce energy consumption improve energy efficiency with cost effective manners and healthcare concept. The proposed algorithm automatic adjustment air conditioning temperature below the outdoor temperature as recommended from physiologists. In addition the proposed energy efficient Air-conditioning system equipped with embedded tools to collects and monitor energy information for each air conditioning through measurements of current, voltages, frequency, active power (kW), reactive power (kVAR), apparent power (kVA), power factor (PF), total harmonic distortion (THD) to increased awareness of the importance of energy efficiency and energy saving benefits. The system has three modes of operation; automatic, semi-automatic and manual. The automatic status i.e. the system smartly and completely controls airflow/energy consumption of air conditioner at all times based on Psychrometric Chart; semi-automatic status is designed to quickly and efficiently controlled energy usage with fixed selected temperature value. The manual status is considered as a conventional, delivery and use of energy without any control. The Smart energy efficiency algorithm is set based on psychrometric chart, load importance, comfort level, room temperature, and internet weather service. The proposed novel system leads to achieve comfortable temperature with less energy consumption over many hours during the day. The proposed energy management strategy aims to save around 15-26% of daily energy consumption. Index Terms -Energy-efficient, air conditioning, Energy saving.

The coalescence of a water drop in a dieletric oil phase at a water layer interface in the presence of an electric field is simulated by solving the Navier-Stokes and charge conservation equations with the finite element method. The proprietary software Comsol Multiphysics is used for this purpose. The interface between the oil and water phases is tracked by implementing a level-set approach. Preliminary simulations to assess the sensitivity of the model with respect to some input parameters are reported. In particular, the calculations are very sensitive to the size of the computational grid elements and the interface thickness parameter. Nevertheless, the model is able to reproduce the occurrence of partial coalescence for the experimental case examined. Good quantitative agreement can be obtained if the parameters are suitably tuned.

Introduction

The application of an external electric field is a technique currently used in the oil industry to promote migration and enhance coalescence of droplets in the water-in-oil emulsions formed during the oil extraction process [1, 2]. It is generally acknowledged that the effect of the electric field is to increase film drainage and hence the thinning rate between two coalescing droplets [1]. However, an excessive value of the field strength can reduce the quality of coalescence, as secondary droplets form [3-6] as a result of an incomplete coalescence process. The efficiency of the process would be significantly improved if the operating conditions to prevent partial coalescence from occurring were known. In this regard, it has been shown [5] that the ratio between the volume of the secondary droplet formed and the initial drop volume can be described as a function of a dimensionless number which is the product of the Weber and Onhesorge numbers. The same authors have recently addressed the effect of the electric field type on the coalescence quality. Their experimental results have revealed that the volume of the secondary droplet decreases if pulse-DC fields are applied, leading to the transition from partial to complete coalescence under certain conditions [6]. These findings can have an important impact on the development of compact electrocoalescer designs. The aim of this work is to provide a mathematical description of the phenomenon. For this purpose, a finite element approach combined with the level-set method [7] is adopted in this work to analyse the process of partial coalescence. To the authors' knowledge, there are no attempts at predicting numerically the occurrence of incomplete coalescence in the presence of an electric field. The proprietary software Comsol Multiphysics (Comsol, Sweden) software has been used for this purpose, in an attempt to assess the capability of the proposed approach to reproduce and analyses the phenomenon.

Model Equations

A level-set approach is employed to track the boundaries between different phases. The evolution of the boundary is described by the equation: where is a smooth step function which varies from 0 to 1 across different phase domains, is a reinitialization parameter which gives stability to the solution and is related to the thickness of the interface. The fluid velocity is denoted by u (bold letters denote vectors). It should be noted that Eq. (1) is the non-conservative formulation of the level-set equation, which attains convergence more easily but introduces some errors in the calculations. However, the non-conservative formulation is more suitable for a rapid test of the model capabilities. Navier-Stokes and continuity equations are solved using average physical properties for the two phases: where and are the volume fraction weighted density and viscosity, which differ from the pure liquids properties only at the interface. In eq. (2), forces due to surface tension and induced by the electric field are included. The force due to surface tension is calculated as: where is the surface tension coefficient, the local surface curvature, n the outward pointing interface normal vector and d is a smooth approximation of the Dirac function which is non-zero only at the interface. The electric force is calculated from the divergence of the Maxwell tensor: where is the average permittivity. The electric field E is computed by satisfying the charge conservation equation: where is the average conductivity. With reference to the computational domain depicted in Fig. 1, the following boundary conditions have been applied in order to solve this set of equations: the upper boundary is kept at a fixed electric potential while the opposite one is earthed and no-slip conditions are prescribed for both boundaries; the domain is axisymmetric; slip conditions are considered on the right boundary, as this allows significant reduction of the simulation domain. The properties of the two liquids correspond to the sunflower oil/water system investigated experimentally by Mousavichoubeh et al. [5] and are reported in Table 1. The interfacial tension is equal to 25 mN mm^–1, as measure experimentally. In order to assess the effect of and the mesh element size, the following case is analysed. The initial drop size is 1.196 mm and the electric field strength is 373 V mm^–1. Under these conditions, partial coalescence occurs and the ratio between the volume of the secondary droplets formed and the initial drop volume is equal to about 0.088, as measured by Mousavichoubeh et al. [3].

Results

The calculated values of this ratio are reported in Table 2. For all cases, the reinitialization parameter is set equal to 1 m/s, which is comparable to the maximum fluid velocity in the system. The results shown in Table 2 reveal that the tuning of the interface thickness, is strictly connected to the level of mesh refinement (hmax/D is the maximum element size in the computational grid). With, the calculated volume of secondary droplets becomes invariant with the grid element size when this is sufficiently small. In this case the volume ratio of the secondary droplet to that of the initial drop is very close to the experimental value. However, the phenomenology described in the two simulations is different, and the results are compared in Figs. 2 and 3. The value of does not produce realistic results and convergence fails in a number of cases of the behaviour observed experimentally is also reported in Fig. 4. The numerical results obtained with reproduce the experimental observations exactly, whereas with a jet-like behavior is reproduced. This may be due to the larger interface thickness, which makes the droplet more deformable and the break-up process more difficult, although the predicted volume ratio is very close to the experimental value. problems, and a solution is obtained only for, which, however, provides a higher value of the secondary droplet volume formed as compared to the experiments. Decreasing further the grid element size to 0.02 causes non-convergence again, as should usually be smaller than the maximum grid size. This requirement becomes more critical when is small.

Conclusions

A model to describe partial coalescence in the presence of an electric field has been proposed. It has proved to be capable of reproducing the phenomenon observed in experimental work previously reported in the literature. A satisfactory quantitative agreement can be achieved by the right selection of the interface thickness parameter and computational grid size. This study constitutes the basis for the development of a reliable mathematical description which can be used for the design of a compact and efficient electrocoalescer.

Acknowledgement

This work was made possible by NPRP grant #5-366-2-1435-366-2-143 from the Qatar National Research Fund (A Member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.

References

[1] Mhatre, S., Vivacqua, V., Ghadiri, M., Abdullah, A.M., Al-Marri, M.J., Hassanpour, A., Hewakandamby, B., Azzopardi, B., Kermani B., 2015. Electrostatic phase separation: A review. Chem Eng Res Des, 96, 177-195.

[2] Vivacqua V., Mhatre S., Ghadiri M., Abdullah A. M., Hassanpour A., Al-Marri M. J., Azzopardi B., Hewakandamby B., Kermani B. (2015). Electrocoalescence of water drop trains in oil under constant and pulsatile electric fields Chem Eng Res Des, doi:10.1016/j.cherd.2015.10.006.

[3] Aryafar H., Kavehpour H.P. (2009). Electrocoalescence: Effects of DC electric fields on coalescence of drops at planar interfaces, Langmuir 25 (21), 12460-12465.

[4] Mousavichoubeh M., Ghadiri M. and Shariaty-Niassar M., 2011a. Electro-coalescence of an aqueous droplet at an oil–water interface, Chem Eng Process, 50, 338-344.

[5] Mousavichoubeh M., Shariaty-Niassar M. and Ghadiri M., 2011b. The effect of interfacial tension on secondary drop formation in electrocoalescence of water droplets in oil, Chem Eng Sci, 66, 5330-5337.

[6] Mousavi, S.H., Ghadiri, M. and Buckley, M., 2014. Electro-coalescence of water drops in oils under pulsatile electric fields. Chem Eng Sci, 120, 130-142.

[7] Sethian, James A. (1999). Level Set Methods and Fast Marching Methods: Evolving Interfaces in Computational Geometry, Fluid Mechanics, Computer Vision, and Materials Science. Cambridge University Press. ISBN 0-521-64557-3.

Background & Objectives

Drilling systems are used to identify geological reservoirs and carry out extraction of oil or natural gas from these reservoirs. Deep wells are drilled by using rock-cutting tools driven from the surface by a slender structure of pipes called a drill string. These slender rotating structures can experience undesired dynamics, which can be detrimental to the drilling system. As an example, it is mentioned that stick-slip oscillations can be an important cause for drilling inefficiency and failure of drill-string components, as violent torsional motions and large amplitude lateral motions can occur during these oscillations. As a step towards the development of appropriate vibration attenuation schemes, it is intended to study the nonlinear behavior of slender rotating structures representative of drill strings. In particular, efforts underway at Qatar University to develop a laboratory scale experimental arrangement to study these structures will be presented and discussed. Prior efforts undertaken in this area will also be briefly reviewed. Brief Review and Qatar University Experimental Arrangement Drill-string motions are important to understand the complex system behavior of a drilling system, in particular, as they relate to downhole vibration phenomena. As shown in Fig. 1, the drill string is a complex, flexible structure, which consists of hollow steel pipes screwed together to form a long continuous structure. Large diameter sections, which are referred to as stabilizers, are inserted between two drill pipes to help keep the drill string centered in the borehole. The base of the drill string is made up of two main components, namely, the drill collar and the drill bit. The drill bit, a tool which breaks down the rock and soil, is secured at the end of the drill-collar assembly. The composition of drill pipes, stabilizers, and drill collars is referred to as the bottom-hole assembly (BHA). The entire drill-string assembly is rotated at the surface by using a rotary table and a motor. This actuation is transmitted down the drill string and to the drill bit, which acts to crush the rock and soil. Throughout the drilling process, a hydraulic fluid, known as drill mud, is pumped down through the center of the drill string and collars. This drill mud serves two purposes. It not only keeps the drill bit cool and lubricated, but it is also used to wash away the soil and cut rock. After the mud flows through the drill-strings and the collars, it flows then in the annulus between the drill-string and borehole carrying the cuttings to the surface. During operations, a drill string can experience a whole range of vibrations, including axial, torsional, and lateral vibrations. Drill-string vibrations are sometimes further grouped together as vibrations without contact without the borehole, whirling motions (forward and backward) during which there can be rolling and sliding contact with the borehole, and snaking motions which are a form of lateral vibrations during which a part of the drill string rolls over a borehole contact point. Given that drill strings are long, slender structures, the first torsion natural frequency and the first bending natural frequency are typically in close proximity. In addition, the nature of the system allows for coupling and energy exchange between torsional and lateral motions. In order to focus on the behavior of drill strings in the BHA region, a number of studies have been conducted, with several including studies with scaled laboratory scale arrangements. A partial list of references is included at the end of this paper. Focusing on some of them from this list, in earlier work conducted at the University of Maryland, Liao (2011), Liao, Balachandran, Karkoub, and Abdel-Magid (2011), Liao, Vlajic, Karki, and Balachandran (2012), the focus was on stick-slip motions and whirling. Comparisons were made between experimental and numerical results. It was shown that the nonlinear nature of the contact force interactions is critical for capturing some of the associated phenomena. In a follow up study conducted by Vlajic (2014), forward and backward whirling motions were explored and the development of appropriate reduced-order models was continued. In the work carried out by Shyu (1989), which include validation with laboratory and field studies, a focus was on the coupling between lateral and axial vibrations. Later motion instabilities were experimentally investigated in the work of Berlioz, Der Hagopian, R. Dufour, and E. Draoui (1996). Other notable examples include the studies of Antunes, Axisa, and Hareux (1992), Kust (1998), Mihajlovic (2005), Gao and Miska (2008), and Khulief and Al-Sulaiman (2009). These studies will be reviewed during the conference presentation. In order to build further on previous experimental efforts and related analytical and numerical studies, efforts are underway at Qatar University to build a laboratory scale arrangement to focus on stick-slip oscillations and whirling. Some representative motions of interest are shown in Fig. 2. The proposed system, which is to be used to capture the dynamics in the BHA region, is also shown in Fig. 1 with dimensions. Details of this arrangement will be presented at the conference. It is expected that the proposed arrangement will help explore stick-slip interactions further and gain insights into different aspects including drilling mud that can be beneficial for drill-string vibration attenuation and realizing desired BHA dynamics.

Keywords

Rotor-stator interaction, Dry friction, Stick-slip motions, Torsional vibration, Whirling

Acknowledgment

The authors would like to gratefully acknowledge the support received from the Qatar National Research Fund for NPRP Project 7-083-2-041, to pursue this collaborative work between the University of Maryland, College Park, MD, USA and Qatar University, Doha, Qatar.

References

Antunes, J., F. Axisa, and F. Hareux. “Flexural vibrations of rotors immersed in dense fluids, Part II: Experiments,” Journal of Fluids and Structures 6 (1), 1992, pp. 3-21.

Berlioz, A., J. Der Hagopian, R. Dufour, and E. Draoui. “Dynamic behavior of a drill-string: experimental investigation of lateral instabilities,” Journal of Vibration and Acoustics 118 (3), 1996, pp. 292-298.

Gao, G. and S. Miska. “Dynamic buckling and snaking motion of rotating drilling pipe in a horizontal well,” SPE Journal 15(3), 2010, pp. 867-877.

Khulief, Y. A., and F. A. Al-Sulaiman. “Laboratory investigation of drillstring vibrations,” Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223 (10), 2009, pp. 2249-2262.

Kust, O. “Selbsterregte Drehschwingungen in Schlanken Torsionssta”- ben-Nichtlineare Dynamik und Regelung. PhD Dissertation, University of Hamburg-Harburg, Hamburg-Harburg, Germany, 1998.

Liao, C.-M. “Experimental and numerical studies of drill-string dynamics,” PhD Dissertation, University of Maryland, College Park, 2011.

Liao, C.-M., B. Balachandran, M. Karkoub, and Y. L. Abdel-Magid. “Drill-string dynamics: reduced-order models and experimental studies,” Journal of Vibration and Acoustics 133 (4), 2011, pp. 041008-1-041008-8.

Liao, C.-M., N. Vlajic, H. Karki, and B. Balachandran. “Parametric studies on drill-string motions,” International Journal of Mechanical Sciences 54 (1), 2012, pp. 260-268.

Mihajlovic, N. “Torsional and lateral vibrations in flexible rotor systems with friction.” PhD Dissertation, Technische Universiteit Eindhoven, 2005.

Shyu, R.-J. “Bending vibration of rotating drill strings,” PhD Dissertation, Massachusetts Institute of Technology, 1989. Vlajic, N. A. “Dynamics of slender, flexible structures,” PhD Dissertation, University of Maryland, College Park, 2014.

The wide spread application of boron in various industries such as glass and fiberglass, ceramics, abrasives, detergents and soaps, fertilizer, enamels, insecticides, semiconductors, cosmetics and pharmaceuticals has left many surface and waste water streams polluted. Thus, there is a growing global demand for new chelating materials and efficient separation systems for removal of boron from different water streams. This is because the existing boron removal technologies are challenged by slow performance coupled with high treatment cost caused by strict low boron concentration required in water bodies and discharged wastewater to meet the newly imposed regulation [1]. Selective adsorbents obtained by modification of polymeric fibres with radiation induced grafting of functionalized monomers are potential materials for improving the performance of current ion exchange systems operated based on granular chelating resins for boron removal to desired low levels [2]. In this work, a new adsorbent having microfibrous structure was prepared by radiation induced grafting of 4-chloromethylstyrene (CMS) onto nylon-6 fibres waste followed by functionalisation with N-methyl-D-glucamine (NMDG) and testing for boron removal from solutions in batch and continuous column modes as schematised in Fig. 1. The degree of grafting (DOG) in the adsorbent precursor was tuned by variation of reaction parameters and and optimum DOG of 130% was achieved at a CMS concentration of 20 vol% in methanol, a total dose of 300 kGy, a temperature of 30 °C and a reaction time of 3 h. A maximum glucamine density of 1.7 mmol/g was loaded in the adsorbent at 121% DG, 10.60% NMDG concentration, 81 °C reaction temperature and 47 min reaction time. The chemical composition, morphology and structural changes in nylon-6 fibres caused by grafting of CMS and subsequent glucamine treatment were monitored by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The thermal properties were determined using differential scanning calorimetry (DSC) and the thermal stability was evaluated by thermogravimetric analysis (TGA). The mechanical properties were investigated with a universal mechanical tester. The obtained fibrous adsorbent displayed an increase in the average fibre diameter compared to original and grafted fibres (Fig. 2). The adsorbent showed 100% removal efficiency for boron removal from solutions at an initial concentration of 100 mg/L, temperature 30 °C, reaction time 2 h and pH of 7. The new adsorbent can also achieve a maximum adsorption capacity of 13.8 mg/g at pH 7, which is 20% higher than that of commercial granular resins. The adsorption isotherm of boron on the fibrous adsorbent was best fitted to Redlich-Peterson isotherm model whereas the adsorption kinetic behaviour is well fitted by the pseudo-second-order model. The new fibrous adsorbent also showed rapid kinetics compared to commercial resin as indicated by the reduction in the adsorption equilibrium time from 60 min for commercial resins to 30 min. The breakthrough curves obtained from column studies conducted under dynamic conditions (initial concentration 10 mg/L and pH 7) shown in Fig. 3 suggest that the fibrous adsorbent is about 2.2 times faster than granular resin. The adsorption capacity of boron remained almost constant after five cycles of adsorption/desorption cycles suggesting a good chemical stability. Considering the essential properties such as high external surface area, rapid kinetics, high adsorption capacity, mechanical strength and chemical stability, it can be suggested that the new fibrous adsorbent obtained from nylon-6 fibres waste is highly promising for boron removal from solutions. The technology developed in this work can be harnessed for preparation of various types of adsorbents for chemical decontamination of industrial waste water, surface water and underground water using a variety of waste polymer materials of different morphologies (fibres, fabric and films).

References:

[1] Nasef, M.M., Nallapan, M., Ujang Z. Polymer-based chelating adsorbents for the selective removal of boron from water and wastewater: A Review. Reactive and Functional Polymers 2014. 85, 54–68.

[2] Nasef, M.M., Guven, O. Radiation-grafted copolymers for separation and purification purposes: status, challenges and future directions, Progress in Polymer Science 2012, 37 (12) 1597–1656.

The Arabian Gulf surrounding Qatar is a unique marine environment with high insolation and salinity. Over 2000 strains of yeasts and filamentous fungi were isolated during 4 samplings in the context of a QNRF funded NPRP project. Approximately 1200 of the isolates were yeasts and over 800 were molds. All isolates were identified by molecular barcodes based on the ribosomal DNA. In addition the yeast isolates were also identified by MALDI-TOF MS with success rates varying from 42% [1st batch] to 80% [3rd batch] due to improvement of the yeast panel in CBS MALDI-TOF MS database. Among the yeasts the carotenoid containing red yeasts were abundant together with Candida tropicalis, Debaryomyces hansenii, Clavispora lusitaniae, and Kondoa sp. Also the black yeast genera Aureobasidium and Hortaea were frequently isolated. Among the molds, the melanized genera Cladosporium with the Cl. cladosporioides complex and Alternaria section Alternata were most abundant. Note that melanized and carotenoid containing fungi were the most prevalent fungi isolated, which may relate to the local extreme environmental conditions. Seasonal differences were observed between summer and winter samplings, but also spatial divergence between plots was observed. Potential new species were found in the genera Aspergillus, Penicillium, Alternaria, Cladosporium [all molds], Aureobasidium [black yeasts], Pseudozyma, Rhodotorula/Rhodosprodium and Kondoa [all basidiomycetous yeasts].

In 2009, the average energy consumption was about 16.1 TW. 81 % of it was supplied by non-renewable fossil fuels with emission of 29 × 1012tons of the carbon dioxide (CO2) into the atmosphere.1 Predicting the rise of energy consumption, the world is facing an urgent need for environmentally friendly and renewable energy technologies. As the direct exploitation of the ultimate energy source of the earth surface, solar power is a critical objective for our future. With recent $1 Billion investment in the polycrystalline silicon solar cell production, Qatar is clearly building a global leadership position in the alternative energymarketplace.2Current solar materials is primarily based on crystalline silicon, which is expensive on the energy- and water-intensive production processes due to the nature of the inorganic deposition.3 The newly developed large-scale and low-cost materials/technologies are thus needed for the next-generation solar energy production. The earth-abundant, non-toxic organic polymeric materials (“plastics”) have recently attracted much attention because of their cost-effectivity, flexibility, light weight and potential use in large- area flexible devices. In addition, organic active layers offer versatile design space for the polymer architectures, providing potential for layer designs and tunability to suit specific energy supply criteria.3Indigo is the most produced natural dye with a highly planer bis-lactam structure.4 Such kind of planer bis-lactam structures, such as perylene diimide (PDI), 2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP), and their structure derivatives, have attracted considerable interests as acceptor materials among various optelectronic devices in past decades.3In addition to the structure benefit, its isomer, isoindigo has better conjugate prosperity since its lactam ring conducting with an extended π system throughout the bis-oxindole framework, which results in the strong electron-withdrawing nature alongside their high degree of coplanarity.3,4 Isoindigo was first introduced into organic semiconductors in 20105 and has been widely studied in the following years. More than 100 isoindigo-based molecules had been developed by 2014 and up to ∼7% organic photovoltaic (OPV) efficiencies and 3.62 cm2V-1s-1 hole mobilities in organic field-effect transistor (OFET) have been reached.6,7Among the various modifications of isoindigo-based molecules, the low bandgap donor-acceptor copolymers containing thienoisoindigos (TIIs) and thiazolisoindigos are particularly of interest to us. Replacing the outer phenyl rings of isoindigo with thiophene and thiazole rings, these molecules could further enhance planarity (via S-O interactions) along the backbone,5 resulting in better packing and higher mobilities for both holes and electrons with very low bandgaps through internal charge transfer interactions.Another indigo derivative, 7,14-diphenyldiindolo[3,2,1-de:3′,2′,1′-ij][1,5]naphthyridine-6,13-dione, containing the core of another synthetic dye cibalackrot, is also of interest to us. The cibalackrot was first synthesized by the condensation reaction of nature abundant indigo andarylacetyl chloride in 1914 but its potential usages in semiconductorswas not noticed until 2014.8,9 Our research team is one of the pioneers in this area. Recently, we published a polymer exhibiting OFET devices with holes and electrons exhibiting mobilities of 0.23 and 0.48 cm2V-1s-1, respectively. The OPV device efficiencies reached 2.35% with the light absorbance up to 950 nm, suggesting the potential of this novel monomer unit for implementation in near-IR OPV devices.4 Othercibalackrot containing copolymers are currently being explored.Reference:1. International Energy Agency, Key World Energy Statistics, IEA, Paris, 2011.2. https://www.jccp.or.jp/international/conference/docs/14assessment-of-solar-and-wind-energy-potential-in.pdf3. Guo, X.; Facchetti, A.; Marks, T. J. Chem. Rev. 2014, 114, 8943-9021.4. Fallon, K. J.; Wijeyasinghe, N.; Yaacobi-Gross, N.; Ashraf, R. S.; Freeman, D. M. E.; Palgrave, R. G.; Al-Hashimi, M.; Marks, T. J.; McCulloch, I.; Anthopoulos, T. D.; Bronstein, H. Macromolecules 2015, 48, 5148-5154.5. Mei, J.; Graham, K. R.; Stalder, R.; Reynolds, J. R. Org. Lett. 2010, 12, 660.6. Wang, E.; Mammo, W.; Andersson, M. R. Adv. Mater. 2014, 26, 1801-1826.7. Dutta, G. K.; Han, A.-R.; Lee, J.; Kim, Y.; Oh, J. H.; Yang, C. Adv. Funct. Mater. 2013, 23, 5317-5325.8. He, B.; Pun, A. B.; Zherebetskyy, D.; Liu, Y.; Liu, F.; Klivansky, L. M.; McGough, A. M.; Zhang, B. A.; Lo, K.; Russell, T. P.; Wang, L.; Liu, Y. J. Am. Chem. Soc. 2014, 136, 15093 − 15101.9. http://www.nano2014.org/thesis/view/4220

One-dimensional nanoscale materials continue to attract much attention, not only for a better understanding of the physical properties at low dimensionality, but also for their potential in nanodevice applications. Carbon nanotubes (CNT) are of particular interest because of their unique molecular geometry and of their excellent electronic, thermal, and mechanical properties. Various carbon nanostructures have been successfully used as templates for the growth of novel hybrid nanomaterials, exhibiting highly interesting and unprecedented properties. These nanohybrids mainly consist of carbon nanostructures (mostly nanotubes) decorated by nanostructures of either metallic or semiconductor materials such as Au, Pt, TiO2, ZnO or SnO2. They are often obtained via various conventional chemical processing or through chemical functionalization approaches. In particular, nanohybrids consisting of carbon nanostructures decorated with ZnO nanoparticles have been shown to be promising for applications such as photocatalysts, field emitters, solar cells, and electro-photonic nanodevices. Here we report the successful growth of zinc oxide (ZnO)/single walled carbon-nanotubes (SWCNTs) nanohybrids using a two-step laser process. First, an ultraviolet (UV) excimer laser (ArF, λ = 193 nm) was used to grow SWCNTs using the UV-laser ablation method. Second, ZnO nanostructures were grown onto the SWCNTs by means of the CO2 laser-induced chemical liquid deposition technique (LICLD). High resolution transmission electron microscopy (HRTEM) revealed that the SWCNTs mainly consist of nanotubes featuring a high aspect ratio (diameter around 1.2 nm and length of up to several microns), while the ZnO nanostructures consisted of various morphologies, including nanorods, polypods, and nanoparticles sometimes with a size as small as 2 nm. On the other hand, the x-ray photoelectron spectroscopy (XPS) spectrum of the as-prepared ZnO/SWCNT sample showed clearly core level peaks of Zn, O and C, while the high-resolution XPS C 1s peak at 284.5 eV was attributed to the graphitic carbon C–C bonds abundantly present in the SWCNTs. The O 1s peak at 531 eV was attributed to O2– in the ZnO crystal lattice (i.e., O–Zn bonds), and the strong peak at 1022 eV could be attributed to Zn²⁺ (i.e., Zn–O bonds in the ZnO crystal). The observed peaks at 286.2 eV and 290 eV are considered to originate from the C–OH and O–C–O groups, respectively, and the one at about 533 eV was attributed to surface O–C groups. The presence of oxygen components in the high-resolution XPS C 1s spectrum and the presence of carbon components in the O 1s spectrum suggest that oxygen is directly bonded to the SWCNTs structure through the formation of strong covalent bonds between carbon and oxygen atoms, especially when no Zn–C bonding has been detected. However, these XPS data, along with the microscopy results, highly suggest that the growth of ZnO nanocrystals takes place directly on the walls of the SWCNTs through the formation of –Zn–O–C– bonds, as also reported in the case of other metal oxide/CNT composite materials [1, 2]. The ZnO/SWCNTs nanohybrids were found to exhibit a polychromatic photoluminescent (PL) emission, at room temperature, comprising a narrow near-UV band centered around 390 nm, a broad visible to near infrared band (500–900 nm), and a relatively weak emission band centered around 1000 nm. These PL results are compared to those of individual components (SWCNT and ZnO) and discussed in terms of carbon defect density and charge transfer between the ZnO nanocrystals and the carbon nanotubes. In fact, visible PL of the SWCNT is believed to originate from the combination (or at least one) of the three following phenomena: (i) the presence of short single-walled nanotubes which are known to generate a visible PL, (ii) multiple radiative transitions between energy states of the Van Hove singularities (VHS) of the carbon nanotubes, and (iii) the presence of amorphous and/or disordered sp2 carbon which is known to exhibit broad band visible PL. The PL spectrum of the nanohybrids basically combines the emission features of the separate components (i.e. SWCNT and ZnO) with, however, three main differences. Firstly, the PL peak due to the ZnO nanostructures slightly red-shifts to ∼410 nm, while exhibiting some peak broadening (FWHM of ∼55 nm). Secondly, its intensity was drastically diminished by a factor of about 100 (in comparison with that of ZnO alone). Finally, the relatively broad PL peak centered at ∼1000 nm is more defined and slightly increased in intensity. Thus, the observed quenching of the ZnO PL emission when laser-deposited onto the SWCNTs is believed to be due to charge transfer of photoexcited electrons from ZnO nanocrystals to the empty electronic states of the SWCNTs and/or to partial re-absorption into the complex hybrid structures (i.e., lattice distortions and defective nanostructures acting as non-radiative recombination centers). Quenching and red-shifting of the ZnO near band edge (NBE) in UV-excited PL has already been observed but to a lesser extent in electrochemically grown ZnO/CNT deposits [3]. Such charge exchange is highly promising for photovoltaic PV applications, where the photocurrent generated into such hybrid nanomaterials can be collected whenever the underlying SWCNTs network is appropriately deposited and electrically connected. As a matter of fact, the possibility of photocurrent generation by ZnO nanoparticles anchored to chemically functionalized carbon nanotubes in a photo electrochemical cell has been recently reported [4]. In sum, this clear indication of charge transfer occurring between ZnO nanostructures and SWCNTs is paving the way towards the development of novel ZnO/SWCNTs nanohybrids-based photovoltaic devices.

References:

[1] N. I. Kovtyukhova, T. E. Mallouk, L. Pan and E. C. Dickey: Individual Single-Walled Nanotubes and Hydrogels Made by Oxidative Exfoliation of Carbon Nanotube Ropes. J. Am. Chem. Soc. 125, 9761 (2003).

[2] M. Liu, Y. Yang, T. Zhu and Z. Liu: Chemical modification of single-walled carbon nanotubes with peroxytrifluoroacetic acid. Carbon 43, 1470 (2005).

[3] R. Zhang, L. Fan, Y. Fang, and S. Yang: Electrochemical route to the preparation of highly dispersed composites of ZnO/carbon nanotubes with significantly enhanced electrochemiluminescence from ZnO. J. Mater. Chem. 18, 4964 (2008).

[4] F. Vietmeyer, B. Seger, P. V. Kamat: Anchoring ZnO Particles on Functionalized Single Wall Carbon Nanotubes. Excited State Interactions and Charge Collection. Adv. Mater. 19, 2935 (2007).

Qatar is firmly committed to conserving its biodiversity and is party to the Convention on Biological Diversity 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 including; protected areas, agro biodiversity and desertification, scientific research, education and public awareness. Qatar is home to unique and important habitats, but due to changes in land use and increased development, habitat reduction has emerged as a significant threat to its biodiversity. Qatar is distinguished for its diverse flora that consists of nearly 420 plant species which pave the way for the establishment of the basis gene bank. In accordance with the international conventions which Qatar has recently joined and ratified, the gene bank has conducted ecogeographical surveys about the plant genetic resources. As a result of conducting these surveys, a complete set of seed plants of the Qatari plants genetic resources are conserved as well as integrated database is created to facilitate electronic exchange among relevant stakeholders and countries to use the resources for studies, research, food security and development. A conservation plan is addressed to conserve plant genetic resources to face the challenges of food security in Qatar. This plan is based on Qatar national biodiversity strategy and action plan 2004 and Ministry of Environment national strategy projects 2011–2016. In this study, we focus on the project of Plant Genetic Resources Conservation in Qatar, the project has addressed in five key objectives; plant and seed conservation, molecular genetic characterization, training and capacity building, documentation of Qatar plant genetic resources, and increasing awareness of plant genetic resource's value. We reported that genetic resources department “gene bank” have been collected and conserved 210 seed accessions, 2800 herbarium specimens, and 287 Plant sample for Genetic characterization. On the other hand department of agricultural research start developing field gene bank. Plant genetic resources conservation, including all seed processing and treatments in gene bank “seed cleaning, seeds drying, seed quality test, seeds viability test, seeds germination test as well as store seed at storage rooms. Gene bank make available the conserved germplasm (genetic resources) to several groups of breeders, researchers, graduate and undergraduate students, farmers and other stakeholders. On the other side, we implemented several workshops and training courses about seed conservation in gene bank and access to plant genetic resources and sharing of benefits arising from their utilization. Finally, In fact, Qatar does not have a traditional food insecurity “Lack of access to adequate food during the year due to limited of money”. But food insecurity in Qatar means that Limited resources of biodiversity and agriculture biodiversity resources. As well as it linked to self-sufficiency. Finally, Plant genetic resources provided powerful tools for humanity to control our child's future, and yet not too much been at risk for Qatari genetic resources to be unsustainable, so it is necessary to preserve the natural plant genetic resources on which development is based. Plant genetic resources can be helpful in the achievement of a world without hunger “Food insecurity”.

Arid and semi-arid areas where desertification mainly occurs cover up to 40? of the world's land area. Mongolia is one of the arid and semi-arid areas, which 90? of the land is in effect of desertification. The government of Mongolia recognizes the need of afforestation for combating desertification, however, there are very limited practical afforestation techniques in Mongolia. Nitrogen fertilization, a major technique for afforestation, generally improves growth and physiological characteristics of plants. The optimal fertilizer application scheme may vary by locations due to the different responses of plants to nitrogen fertilization. Therefore, it is necessary to determine the optimal amount and the type of the nitrogen fertilizers for successful afforestation in the desertification area of Mongolia. The objective of this study was to investigate the effects of nitrogen fertilizer (three levels of amount and two types) on growth rate, photosynthesis and transpiration of Populus sibirica seedlings, a representative afforestation species, in Mongolia. In May, 2015, five plots (6 m ×  7 m) were installed at about 2 m distance apart and 2-year-old P. sibirica seedlings were planted in each plot; four plots for nitrogen fertilization and one plot for the control. Nitrogen fertilizers were applied to each seedling with 5 g (N1), 15 g (N2) and 30 g (N3) of urea and 33 g of ammonium sulfate (NS; same amount of nitrogen with N2). The number of seedlings in each plot was 22 for the control, 21 for N1, 29 for N2, 30 for N3 and 24 for NS plots, respectively. Each seedling was drip irrigated with 3 L per day for the first month and with 9 L at 3 day-interval for the rest of the period. Soil inorganic (NH4 ⁺ and NO3 ⁻ ) nitrogen concentration (mg kg^− 1), when measured 3 weeks after the fertilization, increased with the increasing amounts of nitrogen applied (Control: 2.16, N1: 4.33, N2: 4.84, N3: 5.97, NS: 5.53). Root collar diameter (RCD) and height of seedlings were measured in May and August, 2015. Growth rate of RCD and height were calculated as the increase of RCD or height from May to August divided by the initially measured value in May. Net photosynthetic rate and transpiration rate were measured by handheld photosynthesis system (CI-340, CID Bio-Science, USA) at 8:00?10:00 in June and at 16:00?18:00 in July (n?3). The differences in growth rate of RCD and height following nitrogen fertilization were analyzed using analysis of covariance and the differences in soil nitrogen concentration, net photosynthetic rate and transpiration rate following nitrogen fertilization were analyzed using one-way analysis of variance (SAS 9.3 software). Growth rate of RCD (?) was significantly higher only in the NS plot (14.99) than in the control plot (10.42). Growth rate of RCD of urea-fertilized plots did not significantly increase compared to the control plot and showed a tendency to decrease as the amount of urea increased (N1; 13.01, N2: 12.97, N3: 11.17). The decrease in growth rate of RCD with the increasing amounts of urea might be influenced by ammonia toxicity. When ammonium ion from urea is converted to ammonia in alkaline soils, ammonia toxicity which restricts growth of plants occurs. Although 33 g of ammonium sulfate (NS) has the same content of ammonium ion as 15 g of urea (N2), the growth rate of RCD was significantly increased in the NS plot. It can be explained that ammonium sulfate decreased soil pH which resulted in the decline of ammonia toxicity and improved uptake of nitrogen by roots. Growth rate of height (?) was 8.47 for the control, 8.42 for N1, 10.30 for N2, 9.29 for N3 and 8.74 for NS plots, respectively. There were no significant differences in growth rate of height among plots. It was related to the fact that trees concentrate more on diameter growth than height growth in arid environments. In June, net photosynthetic rate (μmol m^− 2 s^− 1) was significantly higher in the N2 (10.79) and NS (11.15) plots than in the control plot (4.05). There were no significant changes in net photosynthetic rate among plots in July, however, net photosynthetic rate showed relatively high values in the N2 (14.26) and NS plots (15.20), similar to the result of June. It seemed that nitrogen fertilization increased net photosynthetic rate. However, net photosynthetic rate was lower in the N3 plot, which had the highest amount of nitrogen, than in the N2 and NS plots. The reason for the lower net photosynthetic rate of the N3 plot can be related to the fact that excessive nitrogen decreases photosynthesis. In June, nitrogen fertilization significantly increased transpiration rate (mmol m^− 2 s^− 1) compared to the control plot (0.68). Transpiration rate of fertilized plots was highest in the N2 plot (2.79), followed by N1 (2.46), N3 (2.03) and NS plots (1.89). Transpiration rate in July revealed no significant differences among plots. Generally, transpiration rate might be increased by nitrogen fertilization with the increase of photosynthesis. However, the change of transpiration by nitrogen fertilization was significant in June, but not in July. It can be explained by the fact that the increase of transpiration occurs at the early stage after nitrogen fertilization. Growth rate of RCD was only increased in the NS plot, although net photosynthetic rate of the N2 and NS plots were higher than that of the control plot. This result might be related to the high transpiration rate of the N2 plot. It was reported that transpiration was decreased in order to reduce the water loss in dry environments. Although our study site is also a dry environment, transpiration was increased by nitrogen fertilization. We speculated that water stress caused by the increase of transpiration limits growth of seedlings. In conclusion, the response of growth and physiological characteristics of P. sibirica seedlings differed with the amount and the type of nitrogen fertilizer. 15 g of urea increased net photosynthetic rate and transpiration compared to other amounts of urea, but growth rate of seedlings did not differed with the amount of urea. Thus, the optimal amount of urea cannot be determined with the three amounts (5 g, 15 g, 30 g) used in this study. Ammonium sulfate and urea which have the same amount of nitrogen increased net photosynthetic rate. However, growth rate of seedlings was increased by ammonium sulfate. Ammonium sulfate seems to be more suitable fertilizer than urea for the early growth of seedlings in the desertification area of Mongolia. However, the effects of urea and ammonium sulfate on growth and physiological characteristics of P. sibirica seedlings were different. Therefore, further studies would be necessary to determine the optimal amount of ammonium sulfate.

Pre-combustion flue gas capture has been emerged as an efficient alternative to circumvent the costly procedures of materials regeneration utilized by the energy industry for CO2 capture and separation. Stability of the porous structure and repeated use at high pressure and high temperature are among the essential requirements for the efficient materials to be used for industrial level CO2 separation. Herein we report the CO2 adsorption-desorption performance of nanoporous covalent organic polymers (COPs), which can operate efficiently and repeatedly at elevated pressure of 200 bars and above. Since, pre-combustion capture also requires removal of hydrogen along with CO2; therefore, nanoporous COP was also tested for hydrogen removal at high pressure. COP material prepared with simple technique from building block monomers of cyanuric chloride and linked with 1,3-bis(4-piperidinyl)propane has enough surface area and pore volume which makes the material capable to store large quantity of syngas at high temperature and pressure. Results indicated that the newly synthesized COP material can adsorbed exceptionally large quantity of CO2 and very little hydrogen at 200 bars and 35°C. Additionally, the adsorption isotherm was exactly matched with the desorption isotherm, suggesting the material has excellent adsorption-desorption characteristics. Similarly, the material has shown very stable performance when used repeatedly and alternatively for CO2 and hydrogen after regeneration at 50°C. The capturing performance of material was also investigated for other gases like methane and nitrogen at various pressures and temperatures. Experimental results revealed that COP material has exceptional CO2 adsorption efficiency, very good selectivity, and strong stability and can be manufacture with simple techniques. Lastly, material is economically attractive when it is compared with the commercially available materials and has exceptional performance contrary to activated carbon, metal organic frame work and monoethanole amine.

Due to the continued growth in hydrocarbon demand, operators in the oil and gas industry are always looking to drill deeper wells in order to access previously unattainable hydrocarbons. High-Pressure High-Temperature (HPHT) wells are now broadly present in places like the Gulf of Mexico, the North Sea, and the Middle East. At such conditions, the effect of salts on the properties and performance of water-based drilling fluids cannot be reliably extrapolated from moderate conditions.

Oil and gas wells are referred to as HPHT wells if their bottomhole conditions are greater than 300°F (150°C) or 10,000 psi (69 MPa). As drillers get into HPHT formations, a number of unique problems are introduced. Well control, for example, becomes more complicated due to narrow pressure margins and higher bottomhole pressures and temperatures.

As a result, this research aimed to test and investigate the rheological behavior of various water-based drilling fluids with a variety of different salinities at HPHT conditions using a state-of-the-art HPHT viscometer. The main equipment for these experiments is CHANDLER Model 7600 High Pressure High Temperature Viscometer. There are only 8 such equipment that exists in the whole world and our university in Qatar has one of them. Working on this experimental research will train the participating students to use one-of-a-kind high end viscometers in the world. The parameters that are gauged in this experiment are viscosity, yield point and gel strength of the drilling fluid when subjected to these conditions. To model this experiment, water based muds of varying salinity were experimented with two different types of salts – NaCl and CaCl2. Also, two percentages, 15 and 25, of each of these two salts are proposed to be used in formulating the water-based fluid samples which corresponds to approximately 9.3 and 10.0 ppg. 25? concentration of NaCl will result in full saturation of the water-based fluid system and thus this percentage represents a maximum value. 15? concentration, however, can represent a middle value between the maximum concentration (25?) and the minimum (0?). Overall, the results attained in this experiment were useful in coming to several conclusions regarding the effects of salinity on the rheological properties of water-based mud. As shown in Fig. 4, the average dial reading increases with the set pressure. It levels off at a maximum pressure of 18,000 psi and then decreases. This was the case for all the samples apart from the CaCl2 at 25?. Salinity is the total of all non- carbonate salts dissolve in water, unlike chloride concentration that represented only by its content. Therefore, the summation of all the salts in the mud can be expressed by salinity. Amani and Hassiba (2012) performed HPHT tests on water-based drilling fluids containing different concentrations of Sodium and Potassium Chloride (NaCl and KCl). They showed that the fluids with these salts followed the Power Law model up to pressures of 20,000 psi. Above that pressure, the shear rate started to vary linearly with shear stress (best modeled by the Bingham Plastic equation). In the presence of different kinds of salt additives to initially increase the weight of the mud, the junction to the point of separation between water and other solids creates and breaks the stable suspension and produces flocculation.

Therefore, at the end it will decrease the viscosity of the mud. Up to some extent, modified starches becomes anionic and free in hydrated water. The flow properties of the drilling fluid must be controlled so that the fluid can function properly. Properties of the fluid such as the plastic viscosity and the yield stress are very important for the success of the rotary-drilling operations and are therefore constantly measured. Viscosity is the measure of a fluid's resistance to flow and is defined as the ratio of shear stress to shear rate. Newtonian fluids are fluids where the proportionality between the shear stress and the shear rate is independent of the shear rate. Newtonian fluids are usually water or fluids with low molecular weight material. However, most drilling fluids are non-Newtonian and experience shear thinning with increased shear rate as shown in Fig. 20. The Bingham plastic and the power law rheological models are non-Newtonian models that were used in the past and are still used today to approximate the behavior of drilling fluids and cement slurries. The majority of the behavioral models for drilling fluids and cement slurries used today include a yield stress. One of these rheological models that fits this kind of behavior at both high and low shear rates is the Herschel-Bulkley model.

The mud was found to start losing its intrinsic properties at 24,000 psi and the concentration of Calcium Chloride was found to have a more profound impact on the rheology than Sodium Chloride. Out of the used rheological models, Herschel-Bulkley had the best fit and could be used to predict the viscosity. Although the cost of calcium chloride is more than sodium chloride per unit, it is still feasible to use this salt as it has a profound effect on the shear stress and other rheological properties of the fluids. In future iterations of this experiment it would perhaps be more useful to record more data points for the salinity level. Observing the results for more salt concentration levels will give a clearer picture of the effect of salinity on the rheological properties of the fluids. Acknowledgement: “This report was made possible by a UREP award [UREP 13-031-2-014] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the author.”

1. Abstract: Silica nanoparticles functionalized with three different active functional groups (C-8, cyano-propyl, and methacrylate (MA)) were synthesized, characterized and applied for the removal of ten carbamate pesticides from aqueous solution. Two methods were used for the synthesis of functionalized silica (grafting and sol-gel method). SEM, FTIR, and HCN were used for the characterization of the particles, while LC-MS/MS was used for the quantitative analysis of carbamate pesticides in the non-treated and treated aqueous solutions. The characterization results indicated the formation of uniformed, spherical and mono-dispersed particles when the cyano and MA particles were prepared by the Sol-gel. Also, results indicated that all of the synthesized particles were enhances for the removal of carbamate pesticides, and MA prepared by the Sol-gel methods had the highest ? removal for most of the carbamate pesticides tested. 2. Introduction: Active functional groups such as C8 and cyano-propyl have good recovery and can selectively react with carbamate pesticides [1]. Also, previous works [2] have shown that methyl methacrylate have some selectivity and high efficiency to bind with carbamate pesticides. Yet, investigations are still needed to improve the selectivity and efficiency of solid phase extraction via surface modifications. Successful identification of the host functional groups that will selectively react with the guest (contaminant or analyte) will be highly important for the purpose extraction and quantification of the specific analyte. Also, the success to immobilize host molecules that react specifically with pollutants in aqueous solution will allow the remediation of water. The objective of this work is to prepare modified silica-nanoparticles by immobilizing reactive functional groups as hosts on the surface of these particles and to characterize and apply these particles for the removal of pesticides from contaminated water. 3. Experimental: 3.1. Material

All the reagents and chemicals used in this study were obtained commercially from Sigma-Aldrich company. The chemicals used were methanol LC-MS grade, octyl-triethoxysilane, 3-cyanopropyltrimethylsilane, trimethylsilyl-methacrylate, silicon dioxide nanoparticles, xylene, hexane, ammonium hydroxide, 3-methacryloxypropyl trimethoxysilane, tetra-ethoxysilane, ethanol, and carbamate standard (46856-U). Using these chemicals, five particles were synthesized: 1. silica grafted with cyano-group; 2. silica grafted with methacrylate particles; 3. silica grafted with C8; 4. cyano-particles synthesized by Sol-gel method; and 5. propyl methacrylate particles synthesized by sol-gel method.

3.2. Preparation of particles

The particles were prepared following previously developed methods by other scientists [3,4].

3.2.1. Preparation of cyano grafted particles Prior to preparation, the silicon oxide (SiO2) was activated by heating overnight. 5.0 g of the activated SiO2 was mixed with 0.347 mL of 3-cyanopropyltrimethyl-silane, and 100 mL of xylene. The mixture was places in sonicator for one hour, and then was heated overnight. After that, the mixture was centrifuged for ten minutes with 5000 rpm. The particles were finally washed with methanol for three times.

3.2.2. Preparation of methacrylate grafted particles 5.0 g of the activated SiO2 was mixed with 0.237 mL of trimethyl-silyl methacrylate, and 100 mL of xylene. The mixture was places in sonicator for one hour, and then was heated overnight. After that, the mixture was centrifuged for ten minutes with 5000 rpm. The particles were finally washed with methanol for three times.

3.2.3. Preparation of C-8 grafted particles 5.0 g of the activated SiO2 was mixed with 0.414 mL of octyltriethoxysilane, and 100 mL of xylene. The mixture was places in sonicator for one hour, and then was heated overnight. After that, the mixture was centrifuged for ten minutes at 5000 rpm. The particles were finally washed with methanol for three times.

3.2.4. Preparation of cyano and methacrylate particles by Sol-gel-method 40 mL of ethanol was transferred into a flask, and both 1.0 mL of ultrapure water, and 25 mL of NH4OH were added to the ethanol. The mixture solution was then stirred for 14 minutes at 4000 rpm. After that, 1.0 ml tetraethyl-orthosilicate diluted in 4.0 ml of ethanol was added to the solution. Finally, the mixture solution above was divide equally into two different bottles. In one of the bottles, 0.578 mL of 3-cyanopropyltrimethyl-silane was added in order to prepare the SolGel-Cyano particles and in the other bottle 0.444 ml of trimethyl-silylmethyl methacrylate was added in order to prepare SolGel-MA particles. 3.3. Instrumentation: The synthesized nanoparticles were characterized by an FEI Quanta 200, USA scanning electron microscope at an accelerating voltage of 3 kV was used for these analyses. Fourier-transform infrared spectroscopic measurements of the samples were obtained in the range from 400 to 4000 cm^–1 using a Perkin Elmer Spectrum 400 FTIR with an ATR detector at a resolution of 4 cm^–1. The elemental analysis were carried out by using CHN analyzer. Then, the synthesized particles examined for their ability to remove pesticides from water. The pesticides were separated and analyzed by LC-MS/MS (Agilent,1290). 3.4. Pesticide treatments and analysis: Six 15-mL tubes were prepared. 1.0 mL of carbamate in acetone was added into each tube and kept to dry overnight in order to avoid the presence of acetone, which is expected to compete with the particles in extracting the pesticides. Then 2.0 mL of deionized water was added into each tube. One of the tube was kept as control (not treated), while the carbamate solutions in the other five tubes were treated with the five synthesized nanoparticles. 0.25 g of the five different nanoparticles were added to the five tubes. The tubes were vortexed for 1 minute, and left to settle for 10 minutes, and then were centrifuged for two minutes at 4500 rpm. The solutions in each tube were transferred into new tubes and analyzed by LC-MS/MS. 4. Results and Discussions: 4.1. Characterization results

The nanoparticles were synthesized and characterized by SEM, FTIR, TGA, and EDX. The results of SEM indicated the formation of relatively small (nano-size) particles (Fig. 1 a-e). Both the cyano and MA particles that were prepared by sol-gel method appeared to be uniformly and homogenously spherical (Fig. 1 d,e), unlike the other particles, which were prepared by the grafting method. According to the CHN analysis results (Table 1), the amount of C, H, and N elements were relatively high in the particles prepared by Sol-gel methods compared to those prepared by the grafting methods, with highest percentage found in the MMA particles prepared by the sol-gel methods. According to the FTIR results (Fig. 2 and Fig. 3), different patterns were observed for the different synthesized particles and there was indication of OH present in the MMA particles that was prepared by sol-gel method, The different structures of the synthesized particles were clearly in the fingerprint region of the FTIR spectra. 4.2. Pesticide treatments and analysis results: The carbamate pesticides were fully separated as observed in the chromatogram in Fig. 4. Retention times of the pesticides belonging to the chromatogram are shown in Table 2. Also, the table shows the areas of the peaks belonging to the pesticides in the chromatogram before and after treatments with the five synthesized particles. It is clearly observed that the concentration of pesticides significantly went down after treatment with the particles. For most pesticides, the MA particles prepared by the Sol-gel methods showed the highest removal of pesticides. 5. Conclusion: Both cyano and MA particles prepared by the Sol-gel appeared to more uniformed, spherical and monodispersed under the scanning electron microscope and gave higher relative amounts of C, H, and N elements. MA particles prepared by the Sol-gel was the most efficient in removing the pesticides, although all synthetically prepared nanoparticles showed promising result in removing the pesticides. More investigation is required to determine the prober dose of these particles and to examine the effect of pH, temperatures, contact times, as well as the concentration of pesticides. Also, more invistigations are needed to determine the efficiency of these particles to remediate solutions contaminated with other pesticides such orgonophosphorous and chlorinated pesticides. Acknowledgement: This article was made possible by grant QU [QUST-CAS-SPR-13/14-23]. The statements made herein are solely the responsibility of the authors. References: M. Ferna'ndez, Y. Pico', J. Manes, “Determination of carbamate residues in fruits and vegetables by matrix solid-phase dispersion and liquid chromatography–mass spectrometry,” Journal of Chromatography A, 871 (2000) 43–56.

C. Baggiani, L. Anfossi, P. Baravalle, C. Giovannoli, C. Tozzi,” Selectivity features of molecularly imprinted polymers recognizing the carbamate group” Anal. Chim. Acta, 2005, 531, 199.

E. Effati, B. Pourabbas, “One-pot synthesis of sub-50 nm vinyl- and acrylate-modified silica nanoparticles,” Powder Technology, 2012, 219, 276–283.

R. Brambilla, G. P. Pires, J. H. Z dos Santos, M. S. L. Miranda, B. Chorink. “Octadecylsilane-modified silicas prepared by grafting and sol–gel methods,” Journal of Electron Spectroscopy and Related Phenomena, 2007, 156–158, 413–420

Introduction: Industrial pipelines for multiphase transportation can result in unstable flows which often cause major operational problems. Due to liquid wave growth and phase interactions (hydrodynamic slugs), liquid arriving in larger, intermittent chunks may cause flow instabilities in pipelines. At an increased air volumetric flow rate, the surface wave amplitudes become larger to the pipe/conduit and wave forms frothy slug where it touches the wall of the pipe. When the slugs travel at a velocity higher than average liquid velocity, it can cause severe vibration that could reduce the integrity of or damage equipment. In order to tackle the problems associated with slug flows, there is a clear need to better understand the multiphase flow leading to various flow phenomenon in the pipelines. The multiphase flows are characterized by flow patterns or regimes that define a particular distribution of phase volume fraction in pipeline.

While there are several numerical models characterized the development and evolution of slugs and slug flows, studies which describe the stress analysis of these slug flows and their effects are scarce. This study compares two CFD codes (ANSYS CFX and FLUENT) in slug development in jumper and the stress analysis of slug movement in jumper. As well, the effects of flow parameters such as fluid superficial velocity, fluid density ratio, and viscosity on slug were investigated.

The model considered in the present study is based on a quasi-3D formulation where the governing equations are based on volume averaging and ensemble averaging of Navier-Stokes equation. In present study, proposed benchmark relies on focusing on two CFD tools, FLUNT and CFX, to simulate surface instabilities and slugs on stratified flow in a horizontal channel considering slip, surface tension, and frictional momentum transfer between the phases (liquid and gas).

FLUENT Set-up The setup mimics the modified version of the experimental study previously investigated by Vallee and Hohne (2007), the flow channel with rectangular cross-section was modelled using Computational Fluid Dynamics (CFD) package, FLUENT code. The dimension of the model are 4000 ×  300 ×  30 mm³ (length ×  height ×  width). The simulation was performed by a grid consists of 4 ×  462 hexahedral elements and 4 ×  46152 nodes applying a quasi-3D model that consider the wall effect of channel in a 2D model. The volume-of-fluid (VOF) model is used for modeling the fluid domain with air and water. This model is well suited for separated flows with no mixing at the interface. The fluid interface shape is represented by geometric reconstruction scheme. For the two-phase flow, 1.0–1.5 m/s superficial velocity of water and 5.0–11.5 m/s of air were chosen for the CFD calculations. The model inlet was divided into two parts: in the lower half of the inlet cross–section, water was injected and in the upper half air. An initial water level of 50 mm was assumed for the entire model length. As well, initial inlet velocity 1 m/s was considered for water and air, and the velocity of air was increased gradually to simulate different scenarios until final velocity 11.5 m/s considered in this work. The reference pressure considered during the simulation was 1 bar and surface tension of 0.072 N/m. A hydrostatic pressure was also assumed for the liquid phase. For surface instability generation with subsequent slugs, the interfacial momentum exchange and turbulent parameters had to be modeled accurately (Razavi and Namin). In this regard, turbulent model of K-ε model was chosen as the viscosity that is able to model surface instabilities and turbulence of slug flow. Solution for calculating 15s of simulation time on 6-processors lasted for 48 hours. Selected discretization schemes were PRESTO for pressure, Geo-Reconstruction for volume fraction, and First Order Upwind for other cases. Variable time step between 10–6 and 10–3 was appropriate steps for the simulation.

CFX Set-up Building the geometry in ICEM, the mesh was then imported to the ANSYS CFX-Pre in order to define the simulation parameters. Air and water were defined as the two gaseous and liquid phase and using the expressions, the height of water is set to 0.05 (half of the area section) through the entire domain. According to (Frank, 2005), Shear Stress Transport (SST) turbulence model was selected for the simulation and the term “Production and Dissipation” was added to the equations. Surface tension coefficient was set to the value of 0.072 (N/m), interface length scale to 1 (mm), and drag coefficient to 0.44 ( − ) (Frank, 2005). The mixture model was chosen for the interphase transfer. The inflow type was chosen as ‘inlet” and the fractional intensity was set to the value of 0.05 with the eddy length scale equal to the liquid height at the upstream (Razavi & Namin, 2011). The mass flow rate of air and water were set to the values of 0.074 (kg/s) and 7.83 (kg/s), respectively. Several simulations were conducted in order to improve the simulation results and due to the blockage of the outlet in the previous runs, the outflow boundary type was set to “opening” instead of “outlet” with a pressure controlled and medium intensity (5%) turbulence in the boundary details.

The liquid and gaseous phases were defined based on their volume fraction in downstream at outflow. The wall boundary type was set to “wall” and for both phases “no slip wall” and “smooth wall” options were assigned to the mass and momentum and the wall roughness, respectively (Hohne, 2009). The analysis type was set to transient with the total simulation time of 8 (s) and time steps of 0.001 (s), according to the similar study conducted by (Razavi & Namin, 2011). In the solver control, a second order backward Eulerian approach was chosen with high resolution turbulence. Due to the instability and fatal errors in the previous simulations, the minimum and maximum number of loops were set to 1 and 200 (due to divergence problem), respectively with the convergence criteria of 1 × 10^–4.

Figure 1: Abnormal flow simulations (L =  4 m, D =  0.3m, Ug =  9 m/s and Ul = 1 m/s). References: S.Y. Razavi and M. M. Namin. Numerical Model of Slug Development on Horizontal Two-phase Flow, Proc. of Int. Conf. on Recent Trends in Transportation, Environmental and Civil Engineering 2011.

A. Ashrafian, J-C. Barbier and S.T. Johansen. Quasi-3D Modeling of Two-Phase Slug Flow in Pipes. 9th International conference on CFD in the minerals and process industries CSIRO, Melbourne, Australia, 2012.

T. Frank. 2005. Numerical Simulation of Slug Flow regime for an air-water two-phase flow in horizontal pipes, The 11th International Topical Meeting on Nuclear Thermal Hydrualics (NURETH-11), Avignon, France, 2006.

R.E.M. Morales et al. 2013. A comprehensive Analysis on Gas-Liquid Slug Flows in Horizontal Pipes. Offshore Technology Conference, Brazil. OTC 24437.

D. Duraivelan, Y. Dai and M. Agrawal 2013. CFD Modeling of Bubbly, Slug, and Annular Flow Regimes in Vertical Pipelines. Offshore Technology Conference. OTC 24245.

Photovoltaic distributed generation (PV-DG) systems are one of the fastest-growing types of renewable energy resources being integrated worldwide onto distribution networks. As the price of solar cells continues to decrease, residential and utility-scale PV installations are becoming popular energy options in the United States and other Western countries. Similarly, in line with the National Vision 2030, Qatar is aiming to embrace solar technology by 20% to meet its growing demand and reduce carbon emissions. The short-term goal for KAHRAMAA Utility in Qatar is to reach 10 MW solar generation in the next years. Qatar resides in the Arabian Peninsula and is blessed with abundant solar resources. For instance, the Global Horizontal Irradiance for Qatar is measured as 2140 kWh/m²/year in 2012, which is one of the highest in the world. However, local weather conditions significantly degrade the performance of the PV output. Some of the major issues include: (1) the temperature on PV panels is significantly higher than the ambient temperature. This affects the performance of the power electronics devices that are attached to the PV panels, such as inverters, and also the PV output due to the stress on the materials; (2) Qatar is prone to frequent foggy weather during the Winter. Thus often leads to sudden drops in the PV outputs; (3) PV panels often need cleaning in Qatar due to soiling; and (4) during winter months, the humidity increases significantly in Qatar, and the scheduling of anti-dust cleaning as well as considering the impact of late cleaning become more important. The above region-specific issues further emphasize the challenges in integrating PV-DGs in Qatar and the potential need for modeling the impacts of weather conditions on the generation out of PV-DGs on the distribution network. The main goals are to devise probability distribution functions for overloading of transformers and cables and failures of different system components. The outcome of this work will be used to (1) quantify the costs of poor power quality on customer premises and system elements; (2) compute the electric system average interruption duration index (SAIDI) and the system average interruption frequency index (SAIFI); and (3) create rare event techniques to simulate the adverse impacts of PV integration. Moreover, the developed model can be used to find the relationship between the energy storage size, which are likely to assist PV integration at the distribution network, and the unexpected weather events.

I. Introduction

Gas to Liquids (GTL) is one of clean alternative fuels which loosely defined terms that is generally used to describe the chemical conversion of natural gas to some type of liquid products. As such, it excludes the production of liquefied natural gas (LNG), but includes the conversion of gas to methanol, liquid fuels, and petrochemicals, being the most common applications. In other words, Gas to liquids (GTL) technology is used to convert a carbon containing feedstock such as natural gas, to synthetic diesel fuels and further developed by oil companies. Fewer studies investigated the use of GTL diesel with the existing diesel engines to study the effect of using this new alternative fuel on the efficiency and emissions in these engines. Hence, the objectives of this study are to investigate the behavior of the GTL – diesel fuel blends in context of different combustion characteristics, engine performance and emissions. It is expected that the outcomes of this study will shed further light on GTL diesel fuel as a clean alternative fuel.

II. Experimental Methods

The experiments were carried out on a T85D single cylinder, four stoke, water cooled, direct injection, compression ignition engine attached to DIDACTA ITALIA engine test bed. An electric dynamometer with motor and a load cell was coupled to engine. Engine specifications are shown in Table 1. Two fuel tanks were assembled in the test bed; one tank was used for convention diesel fuel and the other was used for GTL Diesel. The properties of the used fuel are mentioned in Table 2. It can be observed that the GTL fuel has a lower density and viscosity and high cetane number in comparison with conventional diesel fuel as demonstrated in Table. 2. All these properties are in favor of improving fuel evaporation and mixing with air, which lead to better combustion characteristics.

The engine test bed and the measuring devices are shown schematically in Fig. 1. The in-cylinder pressure was measured by using a water cooled piezoelectric pressure transducer AVL QH 33D which was mounted flush at cylinder head and connected via AVL charge amplifier. The output signal was displayed on Instek GDS-3152 Digital Storage Oscilloscope with 150 MHz sampling rate. Then, the data was transferred to a laptop which saved for further analysis. The crank shaft position was measured using a digital shaft encoder.

The engine speed was measured by using a speed tachometer that used the pulse counting principle to detect the crank shaft speed, while the fuel flow rate was measured by using a calibrated burette and a stop watch. The engine torque was measured by using a load cell. Engine NOx emission was measured by a long life electrochemical sensor at NOVA-7465PK portable engine exhaust emission analyzer. This electrochemical sensor has anodes, cathodes and suitable electrolyte sealed inside it which, when exposed to gasses, produces a small output current. This output is directly proportionally to the amount of NO gas in the sample. A Pre-Amplifier board directly mounted on the top of the sensor boosts the small signal and converts it to an output of 1 mV per PPM. This output is then sent the main microprocessor board, corrected for the calibration then displayed on the LCD display meter. The resolution of the NOx sensor is ±  1 PPM. The test rig is also equipped with a type-K thermocouples to measure air inlet manifold, engine cooling temperatures and exhaust temperatures which were mounted at relevant points. Normal engine test bed safety features are also included. Atmospheric conditions (temperature and pressure) were monitored during the tests.

III. Results and Discussion

In this section, a comparison between the new manifold designs and the standard manifold of the engine in terms of engine performance and emissions is presented. A number of experiments have been conducted when the engine runs at different loads and different speeds. In addition, the results of using conventional diesel, GTL and 50%–50% blends of both fuels will be presented to show the fuel effect on the above mentioned parameters.

A. Engine Performance

Figure 2. Shows the effect of in cylinder pressure change with crank angle for the diesel at 1700 rpm with variable loads fuels. It was obvious when load increases, the pressure increases. The maximum pressure occurs 18.7 ATDC at no load condition. As load increases the combustion duration increases which lead to long the ignition delay period. It can be observed from Fig. 3 that the maximum pressure values of both fuels and their blends are comparable over the whole range of operation. This proves the suitability of the combustion characteristics of GTL fuel and its blends with conventional diesel to be used with the existing engine designs.

One of the important performance parameters of internal combustion engines is Brake thermal efficiency which indicates how energy conversion added by heat is transferred into a net useful output work. The engine brake thermal efficiency, not shown here, increases with increasing of load. In case of variant load constant speed at 1700 rpm operation condition, the efficiency of GTL fuel was slightly lower than conventional diesel and 50%–50% blend with about (1.5%–8%) and (1.3%–7.75%) compared with diesel, respectively. Higher cetane number, Low viscosity and density of GTL fuel properties leads to efficiency degradation compared with diesel fuel. On the other hand, the engine brake thermal efficiency decreases with increasing of speed. In case of constant load variable speed operation condition, the efficiency of GTL fuel was slightly lower than conventional diesel and 50%–50% blend with about (5%–1.7%) and (2%–4%) compared with conventional diesel, respectively.

Figure 4 illustrates that the engine brake specific fuel consumption (BSFC) decreases with increase in load. In addition, it was observed that by using GTL fuel the BSFC decreases by approximately (4.8–17) % and (0.7–6%) compared with GTL and 50%–50% blend. The higher heating value of GTL fuel than conventional diesel improved the BSFC. Besides, as shown in the bellow figure 5. It was observed that GTL fuel had lower BSFC comparable to conventional diesel and 50%–50% blend. It had been found that while speed increases, BSFC decreases. GTL fuel has the lowest BSFC compared with conventional diesel and 50%–50% GTL by approximately average 31.28% and 5.2%, respectively.

B. Engine emissions

Figure 5 shows the version in CO emissions for conventional diesel, GTL and 50%–50% blend at various loads constant speed 1700 rpm. On average, GTL fuel has the lowest CO emissions of about 43% lower than the other tested fuels. It is obvious that the GTL fuel in 50%–50% blended fuel has a significant effect to reduce CO emissions. This is probably due to higher GTL hydrogen to carbon ratio leading to improve the combustion process in addition to the very low aromatic content and higher cetane number in GTL fuel. The variation of CO emission with speed at constant load is displayed in Fig. 5. It shows that a slight decreasing of CO formation whereas the engine speed increases. In general, GTL fuel shows 42% less CO emissions than conventional diesel. The results also demonstrates that 50%–50% blended fuel has a lower CO emissions than conventional diesel by about 24%.

Figure 6 shows the relation between NOx emissions with load variation at constant speed 1700 rpm. The results indicate a gradual increase in NOx emission with load. GTL fuel has the lowest NOx emissions compared with conventional diesel and 50%–50% blends by about 12.8% and 34.6%, respectively. This is considered to be a significant advantage of using GTL fuel. This NOx reduction can be linked with the high cetane number, which reduces ignition delay duration. Figure 6 gives a relation of NOx emission with the engine speed for conventional diesel, GTL and blends at a constant engine load with variation of speed. Overall, NOx emissions decrease as the speed increases. Moreover, it can be observed that the GTL fuel ratio in the blends contributes to greater NOx emission reduction. The 50%–50% GTL blends and the pure GTL fuel give about 4.6% and 10.5% reduction in NOx emissions, respectively, comparing with diesel fuel.

Sulfur content is one of the fuel property that is responsible of sulfur oxides (SOx) emissions which attracted the researchers and engine manufacturers to test a new fuels. In the combustion process, most of Sulphur content in diesel fuel is being oxidized to SO2. These emissions together with exhaust gas from the exhaust system are then mostly vented into the atmosphere where they can be subject to other reactions contributing to the creation of photochemical smog and acid rain. However, some of SO2 in a presence of oxygen can be unfavorably oxidized to SO3. The high temperature of exhaust gas means that SO3 stays in a vapor state and easily combines with after formed in the combustion process. Figure 7 depicts the variation of SO2 exhaust emissions for the tested fuels at constant speed 1700 rpm with load variation. The results show a slight increase of SO2 emissions as the load increases. GTL fuel has a very low SO2 emissions comparing with conventional diesel and 50%–50% blends by approximately 50.1% and 79.6%, respectively.

Figure 7 compares SO2 emissions of the test fueled by conventional diesel, GTL and 50%–50% blends at constant load variable speed operating conditions. On average, GTL fuel gives the lowest emissions, while 50%–50% blended fuel shows about 52.2% reduction. Adding GTL to conventional diesel has a positive effect to enhance the reduction in SO2 emissions. The reduction in SO2 emissions can be explained by the fact that GTL has almost no Sulfur content. Moreover, some SO2 formed during the combustion process combine with hydrocarbons or metals forming sulphates as it can be occurred while using GTL fuel. Metals originate from the products of the engine reciprocating and rubbing abrasion as well as from lubricating oil, fuel (catalyst residue) or erosion of the catalytic emission control system.

IV. Conclusions

In this work, GTL fuel has been used in direct injection diesel engine as a pure fuel and blended with conventional diesel fuel. In cylinder pressure was measured for a wide range of operating conditions to investigate the combustion characteristics of both fuels and their blends. Moreover, engine performance and emissions have been studied in order to evaluate the suitability of GTL fuel as an alternative fuel for engines. The results show that comparable maximum in cylinder pressure for both GTL and diesel fuels. However, the engine efficiency is slightly lower with GTL fuel than diesel fuel. BSFC shows improvements with GTL fuel in comparison with diesel fuel and blends. CO and NOx emissions have reduced significantly when using GTL and 50%–50% blends. SO2 emissions is the lowest reduction due to the fact that the Sulfur content in GTL fuel is close to 0%.

Acknowledgments

This abstract was made possible by a NPRP award [NPRP 7 – 036 – 2 – 018] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.

The need of transporting petroleum products has resulted in increased erosion of pipeline steel components. For decades, pipeline systems have been used for transporting petroleum products. Carbon steel is commonly used for constructing long-distance pipeline projects due to its mechanical durability and economic aspect. However, the erosion of oil and gas transmission pipeline continues to be a great concern to the petroleum industry because of increasing pipeline maintenance cost and failure. Pipeline steels are often subjected to severe erosion during transportation of petroleum products containing a broad range of erodent particles. The process of transporting petroleum product through the pipeline often results in mechanical removal of the oxide film from the pipeline surface, leaving the surface directly exposed to stress and degradation.

Material removal due to solid particle erosion is believed to be a series of impact events that occur in pipelines and cause extensive damage due to change in the solid-liquid flow direction. Erosion of oil and gas pipeline is a complex phenomenon, characterized by the impacting erodent particles on the pipeline walls due to solid-liquid flow, flow restrictions or change in flow direction. The erosion of steel surface by stream of solid particles can result in high material loss and maintenance costs. Unfortunately, there is no universal model that can effectively predict all erosion situations and development of a reliable and effective model for solid erosion process still remains a challenge. Several attempts have been made to understand the effect of different parameters, such as; temperature, particles size and microstructure of both the impinging and eroding surface on the solid particles erosion process. However, each parameter behaves peculiar to each process and is often complex due to interrelated variables involved. Most of these works were focused on lower carbon steel. The results obtained from these works showed that the target material, temperature, impact angle, particle velocity, shapes and sizes play critical roles in the erosion mechanisms. The angle at which the erodent particles impinge the target material accounts a greater percentage of the erosion damage. Levy studied the solid particle erosion behaviors of 1020 and 1075 low carbon steels using SiC particles as erodent at different impingement angles and speeds. The result showed that the microstructure of the steel materials had a significant influence on the crack growth observed on the eroded steel surfaces. Similarly, Green et al. investigated the erosion mechanisms of low carbon AISI 1050 steel material in relation to the carbon content and microstructure. The result revealed that thermally hardened martensitic structures behave better than the pearlitic steels of the same carbon content under normal temperature range. McCabe also studied the effect of microstructure on the erosion of AISI 1078 and 1050 steels at different angles and speeds using 240 grit A12O3 erodent particles. The result exhibited that the erosion mechanisms assumed a brittle mode with increase in particle velocity. Liebhard and Levy conducted a study on the influence of the shapes of erodent particle on the erosion of 1018 steel. The result showed that angular particles caused higher order of erosion compared to spherical particles. However, the impact of these parameters on the erosion characteristics and mechanisms significantly depend on the material pairs and testing equipment.

In another direction, significant efforts have been made to improve the erosion resistance of the pipeline steel over the years. Results indicated that micro-alloying of carbon steels with small amount of carbide and nitrate forming elements have achieved significant success in the erosion resistance of the carbon steels. Micro-alloying with application-specific elements in combination with judicious process control (e.g. shape-forming and heat-treatment etc.) provided carbon steels of high yield stresses and desirable toughness, for example, high strength low alloy (HSLA) steels. Interestingly, HSLA steels are becoming the material of choice for the projects requiring larger pipeline because of their appreciably low price-to-yield ratio. API X-70 and API X80 have been of the commonly used pipeline grades steels due their ability of withstanding the basic erosion-corrosive environment. However, recently, petroleum industry has witnessed an outstanding demand for higher strength pipeline steels e.g., API X100 in order to combat more stringent environment in terms of erosion-corrosion. Recently, TransCanada, one of the frontiers amongst the steel manufacturing industries has produced API X120 steel which is considered as highest grade pipeline steel available in today's market. The erosion behaviour of this newly developed pipeline material has not yet been investigated in detail. It is of essence to understand the erosion mechanism of this newly developed high strength steel, and under various incidence angle and erodent particle velocities. Conducting detailed analysis on interaction of API X120 steel with various erodent particles (e.g. aluminum oxide) at different velocities would be worthwhile in order to understand the erosion characteristics and mechanisms. Understanding the effects of particle velocity and erosion behavior associated with the API X120 in simulated pipeline environment is necessary to minimize the rate of erosion in the petroleum industry and would be helpful in efficient pipeline material selection and design. This study has been made to facilitate understanding of erosion mechanism and its transition with particle velocity which has a direct relation with the erosion damage.

In this study, dry erosion test was performed in order to investigate the erosion mechanism of API X120 steel by employing particle velocities over a range of 43–167 m/s at normal impact angle for different durations within 0–10 min. A dry sand blaster erosion tester was used to study the erosion behaviour of API X120 steel impinged with aluminium oxide particles at room temperature. The equipment was designed to impinge the targeted sample surface with solid particles at different velocities under controlled erosion conditions. Scanning electron microscope and profilometry techniques were used to characterize the eroded API X120 steel surface. The results indicated plastic deformation and embedment of the erodent particle on the target material surface to be the predominant erosion mechanism observed at lower speed, while at high particle speeds the dominant erosion mechanism was observed to be metal cutting of the target API X120 steel surface.

Qatar is undergoing rapid economic growth fueled by its ambitious national vision 2030 which specifically aims to achieve sustainable development. To achieve the latter, durable and sustainable alternatives for municipal solid waste management are needed, especially since Qatar tops most nations in terms of per capita solid waste generation with nearly 2.5 million tons/year of which 60% consists of organic waste. Current disposal methods include incineration, composting, and land filling which generate greenhouse gases that contribute to global warming. At the same time, the soils in most of the country are poor with weak aggregation, low in organic matter, and low water holding capacity. Hence, it makes economic and environmental sense to convert solid organic wastes generated by municipalities into biochars that improve soil quality and act as carbon sink. The suitability of biochar as an effective soil amendment has been related to but not limited to boosting soil fertility by raising soil pH, increasing water holding capacity (WHC) and retention of nutrients in soil, providing a habitat for beneficial fungi and microbes, improving Cation Exchange Capacity (CEC), and reducing nutrients leaching. In addition, biochar has the ability to reduce the emission of the most potent greenhouse gases such as methane (CH4) and nitrous oxide (N2O). The objectives of this study were to: (1) produce and characterize biochars from solid organic wastes commonly found in Qatar municipal waste streams, (2) determine the effects of solid waste-based biochars on major soil fertility characteristics of normal and sabkha soils of Qatar, (3) select the best performing biochars for use in plant growth experiments.

Four feedstocks [paper, landscape waste, wood, and a mixture of all three) were pelletized, dried, and used as precursors for the production of biochars following a 4 × 3 × 3 factor factorial design consisting of the type of precursor (four different municipal solid organic precursors), pyrolysis temperatures (300, 500, and 750°C) and residence time (2, 4, and 6 hours). Feedstocks were pyrolyzed under N2 gas at a flow rate of 0.1 mL min^− 1 using a Lindberg box furnace equipped with an air tight retort. Yields, surface area, and chemical properties [ash content, pH, surface charge, Electrical Conductivity (EC), Total Carbon (TC), and elemental analysis] of biochars with relevance to soil applications were determined. Qatari sandy soils (Normal and Sabkha) from the Ap horizon (0–15 cm deep) were collected, air dried, and 2-mm sieved. The incubation experiment was conducted in greenhouse pots. To each pot, sufficient amount of 0.25-mm sieved biochar was mixed with soil to yield carbon to soil ratios of 0, 1, and 2% (wt/wt). Box-Behnken experimental design was used instead of the full factorial to decrease the number of treatments to a manageable level (126 treatments) with three replications at the center. The biochar-amended soils (Normal sandy and Sabkha soils) were incubated for 120 days in a greenhouse at a 10% (wt/wt) moisture level. Samples of incubated soils were collected at time 0 (T0: after 8hrs) and at time120 (T120: after 120 days of incubation) for evaluation of soil fertility characteristics (pH, EC, WHC, aggregate stability, TCN content, macro, and micronutrients composition). In addition, pots were leached at days 60 and 120 and their leachates weighed, filtered, and analyzed for total organic carbon (TOC), pH, EC, micro, and macronutrients.

The application of biochars from different precursors to normal soil at different application rates showed a slight increase in pH of treated soil compared to the soil control at T0 and T120, particularly for biochars produced at high temperature and application rate. The increased soil pH is attributable to buffering effect of biochars pH which typically increases as the pyrolysis temperature increases. The same trend was observed for EC where the pyrolysis temperature of biochars seems to be the most influential on the normal soil EC, especially as it ages. The aggregate stability for the normal soil did not increase as the biochar application rate increases, except for hard wood-based biochar produced at high temperature which had a positive effect on the aggregate stability. However for sabkha soil, the pyrolysis temperature and biochar rate significantly increased the aggregate stability of this soil regardless of the precursor. This can be explained by the accumulation of organic matter that was favored by the binding of organic biochar compounds to abundant soil minerals through cation bridging and the formation of microaggregates that would then form large soil aggregates. The addition of biochars has significantly increased the total carbon (TC) of both soil types compared to the control soils. The total carbon increased with both application rate and pyrolysis temperature. Biochar pyrolysis temperature and application rates favored increased TC with variation depending on the type of precursor, soil type, and duration of incubation. This may be attributed to the oxidation and microbial activity processes that speeded up the process of mineralization in the soil. Overall, the TC in normal soil was higher compared to the sabkha soil which may be due to the fact that the starting carbon concentration in the normal soil was higher than that of sabkha soil. In terms of water holding capacity, it significantly increased in both soil types following biochar amendment, especially those produced at high pyrolysis temperature. The positive effect of soil amendment with biochars on WHC was most pronounced in the sabkha soil which exhibited markedly increased ability to absorb and retain water after biochar addition. This is likely due to the high surface area and porosity of the biochars combined with the effect of the polarity of compounds on the surface of biochars which physically retain water and/or improve soil aggregation thereby retaining more water in the soil. The addition of biochars to soil had a positive effect on the pH of normal soil leachates but less so on leachates from sabkha soil. Some pH variations were also observed within the pH of the same soil leachates as a function of the type of precursors used to produce biochars, most likely due to difference in initial composition of the precursors. This implies that biochars with greater liming capacity can provide greater benefit to arable soils that require liming. The results of cluster analysis were used to determine the group of biochar-amended soils which are the most significantly different from the control treatment in terms of soil fertility parameters (pH, EC, TC, WHC, aggregate stability, leachate pH, micro and macronutrients). From the four precursors, only two (soft and mixed materials) were found to be most effective for normal soil and all improved sabkha soil. To further narrow the selection, a secondary selection was carried out based on the biochars precursor type, yield, and energy required for biochar production. Two biochars emerged as the best performing biochars for normal and sabkha soils. Biochars produced from mixed materials pyrolyzed at 500–750°C for 4–6 hours of pyrolysis time and used 2% application rate are best for amendment of normal soil while soft and mixed materials pyrolyzed at 300–500°C for 4 hours and used at 0.5–1% application rates as most suitable for the amendment of sabkha soil. These biochars were found to improve all soil fertility parameters, especially in terms of pH and WHC.

From the above discussion, it is clear that Biochar characterization and short-term soil incubations can provide insights into the potential effectiveness of biochar as soil fertility enhancer and aid in the selection of potential biochars that can improve crop productivity. Overall, normal soil seems to require mixed material produced at high temperature and longer time and applied at high rate while sabkha soil required softer materials produced at lower temperature and shorter time and applied a low application rate. This is encouraging results for carbon depleted soil in Qatar where the application of biochar to agricultural soils has the potential to greatly improve soil physical and chemical conditions while serving as a long term carbon sink. These best performing biochars are being tested in plant growth experiments designed to assess their impact on plant biomass and productivity as indicator or their potential in field agriculture in Qatar.

This study to identify the best pre-treatments to improve seed germination of Capparis spinosa according to standard seeds germination protocols and seeds viability test methods.

Capparis spinosa L. (Capparidaceae) Native to the Mediterranean region and Arabian Peninsula. Locally known ‘Shafallah’ and also known as ‘Caper’ both names used throughout the Arab countries for various Capparis species. The plant is very common in the rodat in northern Qatar in the deep alluvial soil. But at last 10 years Capparis spinosa plants Are in danger of extinction from habitat degradation and changes in environmental conditions. The younger flower buds are collected and pickled in salt solutions. They are used as a condiment in many Mediterranean and Arab countries. Young fruits and young shoots with small leaves may be pickled for use as a condiment. Capers has a sharp piquant flavor, which comes from methyl isothiocyanate, arising from crushed plant tissues. The tender young shoots and the small leaves may also be cooked and eaten as a vegetable.

Based on the literature author reported that Capparis spinosa has high economic and medicinal value in many medicine pharmacies, including Arabian medicine, traditional knowledge, and Chinese medicine. Traditional knowledge of Arabian countries Capparis species were used for treatment wounds and problems in the spleen, liver, kidneys and intestines, to dispel gases, for treat skin diseases, to strengthen teeth and relieve backaches. The plant growth Accompanied mainly by Ziziphus nummalaria, Acacia tortilis and Lycium shawii.

In this study, seeds of Shafallah treated with different dormancy treatments included, concentrated sulfuric acid H2SO4 98%, 0.1% and 0.2% potassium nitrate KNO3, hydrogen peroxide H2O2, boiling water, tap water 24 hours, mechanical scarification “removing part of the seed coat without damaging the embryo”, and gibberellic acid GA3 100 ppm, and 200 ppm to improve seed germination of very important native medicinal plants in Qatar. Capparis spinosa seeds used for production and restoration seedling in some protected area and rodat. Pre-treatments have been done with old seed stored in standard gene bank conditions, and fresh collected seeds, this study carried out in Genetic resources Department, Agricultural Research Department, Ministry of Environment.

Viability test of old storage seeds using 2,3,5-Triphenyltetrazolium chloride has given 80%, but the germination percentage of seeds without any treatments gave 8% after 30 days in automated growth chamber machines. Fresh collected seed viability test has given 100%.

The highest germination percentages 98% and the fasting germination rate was obtained using mechanical scarification with fresh collected seeds after germinated in 10 days under automated standard germination conditions in laboratory growth chamber machines. Results visibly suggest the fresh seeds of caper have highest viability and germination percentage more than old storage seeds.

Finally, Qatar is home to unique and important plant genetic resources, but due to changes in land use and increased development, habitat reduction has emerged as a significant threat to its biodiversity. Capparis spinosa showed in different areas in Qatar as green color to our yellow deserts in the summer, The plant is green and flowering in the very dry regions, and the plant gives fruits two times in Qatar. We can use plant in food security and sustainability programmes. We need more education and public awareness to increase awareness about Qatari native important medicinal plants. Keywords: Dormancy, Capparis spinosa L., Germination, Viability, Germination, Qatar.

Although PV has made remarkable progress in reducing costs, the absolute cost is highly related to the reliability of system components, which is determined by the life span in which PV remains fully functioning. Longer life is especially required for the solar panels when their initial cost is relatively high and therefore longer life guarantees their pay back and increases their profit. Indeed great efforts have been spent by manufacturers to make the panels more reliable and durable to the hard environmental conditions. In spite of careful design and production conditions during manufacturing, the environmental cyclic stresses cause irreversible changes in the solar cells that cause them to partially totally malfunction gradually with time. An accurate measurement of power drop over time, (or degradation rate), is essential to all stakeholders, industry, and investors.

What are the factors affecting the reliability of solar PV technology in harsh environments?

PV technologies are designed to deliver amounts of solar electricity, which is varying differently when submitted to harsh environments (temperature, soiling, UV radiation, wind). The temperature is one of the main factors affecting the power output of a PV system. Researchers may explore the so-called NOCT rating or “normal operating cell temperature” which is indicative of module temperature.

Based on the difference between module temperature and ambient temperature, NOCT can be calculated for crystalline Silicon [1], and thin films [2]. However the influence of other environmental factors must be taken into account when determining the amount of energy (in watt-hour or Wh) produced during a period of time to ensure the consistency and performance criteria of PV systems. Solar Test Facilities in Qatar Foundation: In Qatar, prediction of PV performance can be improved through statistical data collected from PV fields. QEERI is collaborating with Qatar Science & Technology Park and GreenGulf on research at the Solar Test Facility, and developing state of the art solar test laboratory facilities, in order to provide information to stakeholders and industry for better deployment of PV technology in Qatar to meet the Energy grand challenges of the country. A wide variety of equipment, tools, and techniques are used to explore and follow-up failures of PV modules for different technologies. Since March 2013 around 20 photovoltaic technologies have been continually tested at the outdoor Solar Test Facility at Qatar Science & Technology Park. Solar energy technologies at the STF include: Crystalline, thin film, including concentrating (thermal Linear Fresnel collector) as well as battery storage. Overview of Solar Test Facility in QEERI: Two years of investigations have revealed the relative performance of different solar technologies in Qatar's climate, their reliability and degradation, and the impact of heat and dust on their efficiency. We found that flat-plate PV yields more energy than concentrating PV, due to diffuse light conditions at the STF [3]. Crystalline silicon and thin film PV had similar average yields. Of all PV technologies tested, only one-showed signs of severe degradation in the first two years. Dust and heat significantly reduced power output, but high levels of insolation in Qatar compensated this problem. Roadmap: • 2010: Initiated by QSTP, GreenGulf and Chevron

• 2011–12: Systems installed

• 2013: Testing commenced

• 2014: QEERI joins collaboration Final Remarks: • We observed from our experimental data analysis that ordinary flat-plate PV is well suited to Qatar's conditions, provided it is cleaned occasionally.

• Still a need to explore NOCT taking into account module and ambient temperature, available solar irradiance.

• Correlation with simulated yearly module generation, module temperature, solar irradiation (GHI, DNI,) as well as soiling conditions. Acknowledgements: We thank GreenGulf and QSTP for providing data from the STF for this study References: [1] International Standard EN-61215; 1993–04.

[2] International Standard EN 61646; 1996–11.

[3] Daniel Perez-astudillo and Dunia Bachour. (2014). Solar Resource Measurements In Doha, Qatar. Qatar Foundation Annual Research Conference Proceedings: Vol., EEPP0697.

Dugongs (“bugarah al bahr” or “cow of the sea”) in Qatar and the wider Arabian Gulf, are animals of both historic and cultural significance to the people in the region. Historically hunted in Qatar, today they are seen as a symbol for conservation in a country that is trying to balance rapid modernization and coastal development with protection of marine biodiversity, as outlined in the Qatar National Vision 2030.

Qatar and the Arabian Gulf are home to the largest population of dugongs outside of Australia and is the most important region for dugongs in the western portion of their range. As long-lived large mammals with low reproductive output dugongs are vulnerable to exploitation and are listed as Vulnerable to Extinction by the IUCN (International Union for the Conservation of Nature). Currently, dugongs in Qatar face many threats including incidental fisheries bycatch and habitat degradation. The extreme marine and physical environment of the Arabian Gulf, as well as the northern limit of dugong distribution, likely means that their life-history differs from populations in Australia. However, there are virtually no life history data for Qatari dugongs and the species remains mostly unstudied.

A solid understanding of dugong natural history is necessary to develop a successful management and conservation program. Our knowledge of dugong natural history in Qatar and the Arabian Gulf is poor compared to our knowledge of dugongs in Australia (where the largest population exists). Although approximately 6000 dugongs were estimated to live in the Arabian Gulf including Qatar, this number has not been verified. Sporadic research has been conducted on the Qatari population, including work in 1986 which recorded the largest single dugong group of 577 individuals in the waters between Qatar and Bahrain. More recently, in 2008, the Qatar Ministry of Environment conducted surveys that expanded the area around Qatar where dugongs were observed.

Our current study applies similar techniques from the past (boat-based and beach surveys) with newer techniques (aerial surveys using Unmanned Aerial Vehicles [UAVs], histological analyses) to provide an updated understanding of when, where, and how many dugongs are present in Qatari waters, along with preliminary information on their population demographics. From our 2014–2015 surveys, we have enumerated individuals in a large herd, consistently spotted in the winter months in similar areas to the 1986 and 2008 surveys. A total of 508 individuals (including 51 cow-calf pairs) were counted using images taken from a UAV. Underwater surveys verified that the major activity was foraging upon a mixed stand of seagrasses, Halodule univernis and Halophila ovalis, in clear, shallow water (

Nowadays, new trends have made possible to reconfigure the traditional power systems in a more efficient way while world energy consumption is being continuously increased. To meet future energy demands, a more flexible, smart and configurable power system is required. To create such systems, microgrids are emerging and becoming a more attractive solution. The microgrid is a weak grid formed with different energy sources (renewable and conventional), energy storages, power electronics, power control systems and different loads. The microgrids are also particularly suitable for communities and regions where adequate renewable energy sources are available such as in Qatar. Therefore, the energy cost can be significantly decreased, energy security ensured, and energy production become environmental friendly with lower carbon footprints.

The energy sources are the major part of the microgrid systems. As a result of increasing environmental awareness and as a consequence of the exhaustible nature of fossil fuels, renewable energy sources (RES) are playing an important role in modern microgrid systems. The RES based power generation systems have several advantages compared to the conventional power generation systems. Some of these advantages are sustainability, pollution-free operation and the possibility of being installed closer to the end users. In the last decades, especially the wind and photovoltaic (PV) based power generation systems have become more popular than other RESs. However, intermittent and stochastic nature of the wind and solar affect the stability, reliability and power quality of the microgrids. For instance, the PV based system cannot produce energy at night or during cloudy conditions, and wind-based systems generate energy that depends on the wind condition. To overcome these limitations, two or more (hybrid) RES, in addition to proper storage technologies, are needed to provide reliable, stable and continuous power to the customers. However, using different types of renewable energy sources in the same microgrid leads to complex control structure because these sources have different dynamic characteristics and need different control structures. Hence, a well-designed energy management and power flow control systems are essential to ensure the extraction of maximum power from these energy sources.

Another part of the microgrid systems is an energy storage system (ESS) that plays a vital role to maintain stability and robustness as well as to improve the power quality of those systems. For these reasons, an effective ESS must characterize high power density as well as high energy density. In recent years, various types of battery technologies are used for energy storage systems. In spite of their maturity and variety, batteries still have limited lifecycle and poor power density, which is an important element for balancing the renewable based power generation systems. Thus, to support and improve the battery performance, lifetime and system cost, hybrid energy storage systems (HESS) can be suggested while comprising supercapacitors (SCs) and batteries. SCs have a number of advantages related to high efficiency (95%), high power density (up to 10000 W/kg),

tolerance for deep discharges, and long life-cycle (500000 cycles at 100% depth-of-discharge). The combination of SCs and batteries allows to have the advantages of both solutions by obtaining high energy density, high power density, high life-cycle, high efficiency HESS and ensuring better power stability when interfacing with the grid. However, batteries and SCs have different charge and discharge characteristics. Therefore, a well-designed energy management and power flow control system is essential for that system to provide efficient operation and long life cycle.

In the microgrid system, power flow should be bi-directional. For example, in case of insufficient energy, the utility grid can support the microgrid, vice versa, in case of exceed energy, microgrid can inject this energy to another microgrid(s) and/or to the utility grid. Therefore, in such systems, power electronic converters are important to allow the power flow between energy sources, energy storage devices, loads, and the utility grid. These power electronic converters not only allow to connect different electric devices together (whether they are loads, generators or storage devices), but also to provide suitable control for optimizing and protecting the whole system. Furthermore, to ensure the power connection between these different units, a direct current (dc) microgrid or an alternating current (ac) microgrid can be used. However, as mentioned above, most of these units are controlled by power converters, and each of these converters requires a dc-link. For this reason, one common dc-link can obtain appreciable savings for such systems.

To ensure power flow between energy storage devices, energy sources, loads, and the utility grid (if needed), energy management algorithm is essential. A well-configured energy management algorithm increases energy efficiency, system stability, and battery life cycle. Therefore, the energy management algorithm and control structures must be defined properly according to system requirements. Several research activities focus on the energy management algorithm for HESS and power flow control algorithm. Types of the developed algorithms depend on the system power, storage techniques, types of energy sources, and operating modes such as grid-connected and/or standalone. However, most of these studies focused on only one microgrid and its control. In reality, more than one microgrid in the same region and different types of distributed generation units in these microgrids are common. Typically, the energy management control structure can be divided into three categories; centralized, distributed, and multi-level control structures. In all three cases, each energy sources and energy storage devices are controlled by the local controller to determine the optimal operating point locally. To increase the impact of the microgrids, the microgrids should be controlled by the same centralized controller. The microgrids also should have monitoring facilities to observe and reconfigure the energy consumption of the consumers.

The main goal of this study is to design, develop and implement novel smart energy management and power control strategy for two grid-connected microgrids. The presented two microgrids have different charactersitics in terms of renewable energy sources and energy storage technologies. Thus, by the proposed smart energy management and power control strategy, the two different microgrids operate at their best efficiency points regardless of different conditions. They can also operate in bidirectional with each other and/or utility grid. For example, if there is exceed power in one of the microgrids, this energy will be transferred to the other microgrid and/or the utility grid, vice versa if there is insufficient power for the local loads, microgrids request power from the utility grid. This innovative feature of the study will be an effective solution for growing microgrids toward securing the increased power demand. Furthermore, this study presents condition monitoring to adjust and reconfigure the energy consumption of the consumers.

To verify the proposed smart energy management and power flow control system, two laboratory-scale microgrids are designed and implemented. As shown in Fig. 1, the proposed prototype consists of two microgrids connected to the utility grid through the grid interactive inverters. These microgrids can also connect to each other through isolated bi-directional converter. In addition to these, each microgrid consists of four subsystems. (1) Wind energy conversion subsystem, (2) PV energy conversion subsystem, (3) Hybrid energy storage subsystem, and (4) Power electronics interface for AC load. Each subsystem has own local controller that can communicate with centralized controllers in order to increase system efficiency. Furthermore, whole system is controlled by a central controller to ensure optimal power flow between Microgrid I, Microgrid II and utility grid. The results of the study will not only benefit the energy management of multi microgrids but will also benefit the power grid operation especially the distribution system creating positive environmental impacts paving the road for future large-scale integration of the smart grid flexible load technology in Qatar.

The solar photovoltaic industry is dominated by crystalline silicon with a global PV market share of 90%. The global PV module production has reached about 40 GW in 2013. Competing with Si PV, thin film photovoltaic modules have reached a market share just below 10%, with dominance by two companies: First Solar for CdTe and Solar Frontier for Cu(In,Ga)(S,Se)2. Derived by the technological learning and economies of scale, solar photovoltaics industry has seen remarkable cost reductions over the past decades. One possible route to further reduce the price of the photovoltaic (PV) module and reach the grid parity is to develop an efficient PV technology based on low cost materials and processes. Thin film PV has a higher potential for cost effective production in the economy of scale than the other technologies in the market today. The competitiveness of thin film technology currently faces three significant challenges in order to achieve widespread market acceptance and adoption:

• Increasing the record efficiencies toward the theoretical limit and beyond

• Increasing the efficiency of modules (particularly, decreasing the gap between lab scale champion cells and production modules)

• Reducing direct materials and processes costs, specifically by reducing the usage of scarce materials resources

At QEERI, the recently launched grand challenge project ATHLOC-PV (Advanced Thin film Low Cost PV) aims to tackle these issues by developing in Qatar an emerging alternative PV technology. Following a roadmap towards thinner, cheaper and more efficient thin film solar cells, the main objective of ATHLOC-PV is to obtain lower cost, lighter weight and durable photovoltaic modules and to accelerate the decrease in the cost/efficiency ratio for thin film PV modules. The overall aim is to demonstrate a new-type of thin-film solar cell of conversion efficiency in the region of 20% capable of environmentally acceptable large-scale production at a manufacturing cost of below 0.5 $/watt with potential for further significant improvements in the future. To reach this objective, two alternative thin film materials are targeted in ATHLOC namely: Cu2ZnSn(S,Se)4 (CZTSSe) and Cu(In,Ga)(S,Se)2 (CIGSSe). The key advantages include favourable optical band gap (1–1.5 eV), low materials usage and consequently a lower energy-payback time, usage of flexible substrates leading to lightweight and the potential of cost-effective roll-to-roll manufacturing, high conversion efficiency potential. In addition CZTSSe has the advantage not to suffer from abundance issues compared to CIGSSe.

Table 1 compares record efficiencies from laboratory research

Thin-film PV permits a higher cost-reduction potential when up scaling to GW production volumes [2] compared to Si wafer technology. However, the limited supply of some elements (i.e. In in CIGSe) and related costs upon considerably increased production volumes present a constraint that has to be addressed. The overall aim of ATHLOC project is to reduce the use of scarce elements and still reach high efficiencies by developing low cost roll-to-roll inkjet printing processes for the fabrication of CZTSSe solar cells [3], we expect to significantly reduce the manufacturing costs of the modules. In this contribution, the objectives and the roadmap of the ATHLOC-PV project will be presented, as well as the strategy foreseen to improve the efficiency and reduce the cost of the Kesterite solar cells.

References

[1] M.A. Green, K. Emery, Y. Hishikawa, W. Warta, and E.D. Dunlop, ‘Solar cell efficiency tables (version 46)’, Prog. Photovolt: Res. Appl. 22, 701 (2014).

[2] C. Wadia, A.P. Alivisatos, and D.M. Kammen, Materials Availability Expands the Opportunity for Large-Scale Photovoltaics Deployment, Environ. Sci. Technol. 43, 2072 (2009).

[3] Xianzhong Lin, Jaison Kavalakkatt, Martha Ch. Lux-Steiner, and Ahmed Ennaoui, (2015) “Inkjet-Printed Cu2ZnSn(S,Se)4 Solar Cells, Advanced Sciences, 2, 1500028 (1–6).

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