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Solar and renewable energies applications got a great interest and attention in the last few decades. Problems related to CO2 emissions, air pollution, Ozone layer depletion, global warming and environment issues raise the necessity for getting a clean and safe energy. For this purpose, the Center for Solar Energy Studies (CSERS) in Libya conducted a huge research work in different applications for solar and renewable energies. One of these important activities is the Solar Gradient Solar Pond technology. It is an effective solar energy collection and storage system which presents a relatively simple and economic method of providing low grade energy with the advantage of annual storage cycle.This paper presents a general review on researches and studies on solar ponds that were conducted by CSERS research team. Tajoura’s Experimental Solar Pond (TESP) is designed as an experimental facility enabling the investigation of various aspects of pond performance. It is constructed by the Center for Solar Energy Studies, in joint cooperation with a Swiss company, with a surface area of about 830 m2, and a depth of 2.5 m, coupled with an evaporative pond of 105 m2 area and 1.5 m deep, equipped with all necessary equipments and measuring control system.The paper also shows the experience of operating MSF desalination unit coupled with TESP solar pond. Finally, other factors affecting the solar pond’s thermal stability were also discussed.

A solar powered desalination unit which working on a humidification –dehumidification technique (HDH) is one of the most important techniques used in brackish and seawater desalination especially in remote and rural areas. In the present study, a test-rig was designed and constructed for conducting a set of experiments on a solar assisted desalination unit working on a HDH principle under the prevailing conditions of Tajoura-Libya. Experiments were carried out on specified days in March, 2019 at the laboratories of Center for Solar Energy Research and Studies (CSERS) at Tajoura. The effect of different design parameters and operating conditions on the performance of the unit and its productivity is closely investigated and interpreted. Results show that the productivity of the HDH unit decreases by increasing the process air mass flow rate. A significant improvement in the productivity of the unit is noticed when the feed water mass flow rate to the humidifier is increased. Furthermore, initial water temperature inside the tank has a remarked effect on the productivity of the unit. In order to obtain a reasonable amount of fresh water, the temperature of the water inside the tank should be increased. Increasing the cooling water mass flow rate to the dehumidifier leads to a corresponding decrease in the surface temperature of the cooling coil and hence the productivity of the unit is improved. The Productivity of the unit is varying from its lower value of (0.903 kg/m2.day) to a higher value of (6.47 kg/m2.day). These values are obtained for one meter square of solar air heater area. Gained Output Ratio (GOR) values range from a minimum of (0.082) to a maximum of (0.572). It is reasonable when compared to ones in literature for the water-heated HDH units.

Adsorption cooling technology is one of the effective means to convert low grade thermal energy in to effective cooling, which improves energy efficiency and lowers environmental pollution. The main objective of this study is to investigate the thermal performance of an adsorption refrigerator theoretically. The working adsorbent/adsorbate pair used is Granular Activated Carbon, GAC/R134a pa*ir. The effect of different design parameters and operating conditions on the system performance is studied and interpreted.Some assumptions and approximations are also considered. A computer program is written using Matlab. Results show that the equilibrium adsorption capacity is highly affected by the driving temperature and equilibrium pressure. Increasing equilibrium pressure leads to a corresponding increase in the equilibrium adsorption capacity whereas it is value is decreased as the driving temperature increases. Moreover, increasing the driving and evaporator temperatures raise the values of the Specific Cooling Effect (SCE) andCoefficient of Performance (COP). The maximum values of SCE and COP are 60 KJ/kg and 0.4 corresponding to driving and evaporator temperatures of 100 oC and 20 oC respectively. However, increasing the condenser temperature leads to a remarked decrease in SCE and COP of the cooling system. SCE and COP values are 32 KJ/kg and 0.22 at driving and condenser temperatures of 100 oC and 40 oC respectively. When comparing the present study results with literature, there is a good agreement in general. It is clear that the adsorption cooling system can be driven effectively by low grade heat sources such as, solar energy, waste heat energy, geothermal energy…etc.

Solar air heaters are widely used in many low temperature applications such as space heating, crops drying, desalination..etc. It collects solar radiant energy and transforms it into heat through a fluid (air) flowing inside the system. The outside cold air is heated through the system and delivered to the required application. It is simple, economic and clean. In this study, an experimental investigation is carried out using a test-rig installed at the laboratories facility for Center of Solar Energy Research and Studies (CSERS) in Tajoura-Libya equipped with all necessary measuring instruments and devices. The aim of this study is to investigate the effect of process air mass flow rate on the thermal performance of a solar air heater working at different operating conditions under the prevailing conditions of Tajoura-Libya. Experiments were conducted on specified days in August 2019, October 2019 and January, 2020.Results show that there is a noticeable increase in the air temperatures of the solar air heater as incident solar radiation values increase during the day time, especially at afternoon. The maximum average outlet air temperature measured reaches 60 oC which is suitable for space heating and crops drying applications. Useful heat energy collected is directly proportional to the incident solar radiation. Increasing air mass flow rates leads to a corresponding decrease in the temperature at different locations in the solar air heater. Furthermore, the average thermal efficiency values of the solar air heater range from 35% to 65%. Average overall heat loss coefficient values tend to decrease with the day time. Finally, the present study results coincide with literature and show a good agreement.

A new design of distributed space time block coding for cooperative relay networks is presented in this paper. The Hadmard matrix and decode-and-forward approach are used at each relay node to generate the new efficient code. Each relay transmits its new code as a linear function of its received signal from the source node. This proposed method uses linear decoding process at the destination node to achieve full data transmission rate and doubling cooperative diversity order without any feedback link between the relay nodes and the destination node. The proposed scheme yields low encoding and decoding complexities at the relay and destination nodes. Furthermore, the simulation results show great performance enhancement without any feedback overhead as compared to regular reported methods.

Endogenous pectin methylesterase (PME) is the enzyme responsible for phase separation and cloud loss in orange juice (OJ) manufacturing. The effect of kiwi's PME inhibitor (PMEI), nanomilling, and pasteurization on OJ quality was evaluated. The microbial quality, PME activity, OJ separation, pH, ascorbic acid content and the sensory characteristics of the juice were followed during 5 weeks storage (4°C). PMEI as freeze‐dried kiwi powder (0.3%, w/w) succeeded in inhibiting 89.3% of the OJ PME without affecting the microbial and the sensory quality. Nanomilling of OJ pulp, to prepare nano‐particles OJ (NPOJ), reduced the initial microbial load by 1.65 and 1.83 log for psychrotrophs and yeasts and molds, respectively; significantly (p, Nanomilling was utilized for the first time in the preparation on nano‐particles orange juice. Such technique along with the use of pectin methylesterase inhibitor from kiwi improved orange juice cloud stability, improved microbial and sensory quality, as well as allowed for the use of a lower pasteurization temperature for a shorter period of times.

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory systemic autoimmune disease. Lung disease has beenrecognized as a common complication of RA. Omega-3 is an essential fatty acid with wide range of activity.Aim of the work: To investigate the possible therapeutic role of omega-3 free fatty acid on the structure of ankle joint andlung in a model of adjuvant-induced RA in rats.Materials and Methods: Thirty adult male albino rats were divided into three groups; Group I served as a control group.Group II was used as a model of RA. Rats of this group were given single subcutaneous injection of 0.1ml of completeFreund adjuvant in their hind paws. Group III (omega 3-treated group), omega-3 was given in as a dose of 300 mg/kg orallyadministered after two weeks of RA induction and continued daily for another two weeks. The ankle joint and the lungs fromall groups were dissected out after two and four weeks and processed for light microscopic examination. Histomorphometricstudies and statistical analysis were also done.Results: RA was confirmed histologically in the ankle joint after two weeks and was aggravated after four weeks. Erosionof articular cartilage and mononuclear cellular infiltration in the synovium were noticed in both time points. Moreover, thelungs after two weeks showed focal inflammatory cellular infiltration and pulmonary fibrosis that were more evident afterfour weeks of untreated RA. This was associated with significant increase in the mean area percentage of collagen fibers andnumber of cells positive for TNF-α immunohistochemical reaction compared to the control group. Omega-3 treated groupillustrated improvement of both ankle and lung structures.Conclusion: Omega-3 significantly ameliorated the structural damage of ankle joint and lung after RA induction.

In this paper, we proposed two Distributed Extended Orthogonal Space-Time Blok Coding (D-EO-STBC) schemes with two terminal nodes, four relay nodes all equipped with single antenna, represented in the first scheme, and two terminal nodes, two relay nodes equipped with dual antennas as a second scheme. Full-data rate and Full-transmission diversity are achievable. Moreover, the second scheme has an advantage of minimizing the decoding complexity at the relay nodes . The simulation results show that both proposed schemes have good performance.

Objectives. To explore the magnitude and determinants of burnout among emergency physicians and nurses working at emergency departments of hospitals in Abha and Khamis Mushait cities.Subjects and Methods. A cross-sectional hospital-based study was conducted in emergency departments of hospitals in Abha and Khamis Mushait cities belonging to Ministry of Health. All physicians (n=95) and nurses (n=187) currently working at these sites were invited to participate in the study by filling a validated self-administered questionnaire including two main sections: personal and professional characteristics of physicians and nurses as well as Maslach burnout inventory (MBI) to assess the three components of the burnout syndrome: emotional exhaustion, depersonalization, and reduced personal accomplishment.Results. The study included 282 physicians and nurses. The age of more than half of them (54.3%) ranged between 31 and 35 years. Most of them (70.9%) were females. About two-thirds of the respondents (66.3%) were nurses while the remaining 33.7% were physicians. Majority of the emergency healthcare professionals (88.7%) had high emotional exhaustion. The prevalence of high depersonalization (cynicism) was 20.6% whereas that of low personal accomplishment was 41.1% among emergency healthcare professionals. The overall prevalence of burnout among healthcare professionals was 16.3%. Multivariate logistic regression analysis revealed that male healthcare professionals were at almost higher three-folded risk for developing burnout compared to females (aOR=2.76; 95% confidence interval (CI): 1.21-6.28, p=0.017)). Smokers were at higher significant risk for burnout compared to nonsmokers (aOR=15.37; 95% CI: 7.06-33.45, pConclusion. A considerable proportion of physicians and nurses working at emergency departments of hospitals in Abha and Khamis Mushait cities had burnout syndrome, particularly high emotional exhaustion and low personal accomplishment.