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In this study, two wind-solar-based polygeneration systems namely CES-1 and CES-2 are developed, modeled, and analyzed thermodynamically. CES-1 hybridizes a heliostat based CSP system with wind turbines while CES-2 integrates heliostat-based CPVT with wind turbines. This study aims to compare the production and thermodynamics performance of two heliostat based concentrated solar power technologies when hybridized with wind turbines. The systems have been modeled to produce, freshwater, hot water, electricity, hydrogen, and cooling with different cycles/subsystems. While the overall objective of the study is to model two polygeneration systems with improved energy and exergy performances, the performances of two solar technologies are compared. The wind turbine system integrated with the comprehensive energy systems will produce 1.14 MW of electricity and it has 72.2% energy and exergy efficiency. Also, based on the same solar energy input, the performance of the heliostat integrated CPVT system (CES-2) is found to be better than that of the CSP based system (CES-1). The polygeneration thermal and exergy efficiencies for the two systems respectively are 48.08% and 31.67% for CES-1; 59.7% and 43.91% for CES-2. Also, the electric power produced by CES-2 is 280 kW higher in comparison to CES-1.

The growing interest in hybrid nanofluids is due to the synergistic effects of nanoparticles, which could give them better heat transfer properties as compared to base fluids, and conventional nanofluids. Several factors like temperature and volume fraction have been used in explaining the behaviours of hybrid nanofluids, however, the need to investigate comprehensively, the mixing ratios of hybrid nanofluids, remains a critical research area in the development of efficient nanofluids as heat transfer fluids. In this study, three mixture ratios of 1:1:1 (33.3% Al2O3, 33.3% ZnO, 33.3% Fe3O4), 1:2:1 (25% Al2O3, 50% ZnO, 25% Fe3O4), and 1:1:2 (25% Al2O3, 25% ZnO,50% Fe3O4) ternary hybrid nanofluid (THNF) are synthesized at volume concentrations of 0.5%, 0.75%, 1%, and 1.25%. All experiments were carried out at a temperature range between 25 °C-65 °C. The effect of temperature, volume concentration, mixture ratio, are examined, as well as the development of a machine learning model for accurate prediction. The thermal conductivity and dynamic viscosity behaviour of the THNF were investigated. The result showed that temperature and volume concentration significantly affected the thermophysical properties of the fluid. The optimum Thermal Conductivity enhancement (TCE) was retrieved for the 1:1:1 THNF, at 36.018%. The 2:1:1, and 1:2:1 mixture ratios had a 32.92%, and 31.68% TCE respectively. At 1% volume concentration, the optimum TCE (as compared with water) for the mono, hybrid, and THNF measured are 18.98%, 28.58%, and 32.45% respectively. It is seen that the least viscosity was recorded for the 1:1:1 mixture ratio (0.001 Pa.s), while the highest viscosity was measured for the 2:1:1 THNF mixture ratio (0.021 Pa. s). The Gaussian process regression (GPR) gave an excellent prediction showing an R2 value of 0.9656, and 0.934 for the thermal conductivity and dynamic viscosity prediction respectively. In terms of application to solar thermal systems, the low viscosity of 1:1:1 Al2O3–ZnO-Fe3O4 THNF makes that a low-pressure drop and pump work is required in practical applications of the 1:1:1 Al2O3–ZnO-Fe3O4 THNF.

The deployment of photovoltaic technology in global electricity generation has reduced the dependence on fossil fuels and the adverse effect of global warming climate changes. However, the variabil...

Unlike previous studies where models/methods used in determining the carbon emission are presented, in this paper, a detailed analysis of the causes, trends, and solutions to carbon emission in Africa is presented. Economic development plays a crucial role in the well-being of a country/continent, thereby, affecting energy consumption. The impact of economic development on Africa's carbon (CO2) emissions trend is first investigated. After which, three neural network models are developed to predict the future trend of total CO2 emission in the continent. Then, the use of renewable energy (RE) sources for power generation is analyzed/proposed as a viable solution for CO2 emission reduction in Africa. Finally, the impact of battery electric vehicles (BEVs) integration and hydrogen production in maximizing RE production in Africa's largest economy is analyzed. Secondary data of the economic indicators for twenty-five different African countries have been used to justify the effect of economic development on their carbon emission. From the results of the analyses, gross national income and carbon emissions in all sectors were found to be significantly positively correlated. That is, as national wealth across Africa increases, carbon emissions in the continent increase. Also, the predicted total annual CO2 emission showed that most countries will witness an increase in total CO2 emission by 2022 in comparison to 2018. The proposed RE-based method for power generation showed that the CO2 emission from the power industry can be reduced to zero for an African country. Nevertheless, the use of BEVs and the production of hydrogen will be integral in achieving this.

Unlike steam and gas cycles, the Kalina cycle system can utilize low-grade heat to produce electricity with water-ammonia solution and other mixed working fluids with similar thermal properties. Concentrated photovoltaic thermal systems have proven to be a technology that can be used to maximize solar energy conversion and utilization. In this study, the integration of Kalina cycle with a concentrated photovoltaic thermal system for multigeneration and hydrogen production is investigated. The purpose of this research is to develop a system that can generate more electricity from a solar photovoltaic thermal/Kalina system hybridization while multigeneration and producing hydrogen. With this aim, two different system configurations are modeled and presented in this study to compare the performance of a concentrated photovoltaic thermal integrated multigeneration system with and without a Kalina system. The modeled systems will generate hot water, hydrogen, hot air, electricity, and cooling effect with photovoltaic cells, a Kalina cycle, a hot water tank, a proton exchange membrane electrolyzer, a single effect absorption system, and a hot air tank. The environmental benefit of two multigeneration systems modeled in terms of carbon emission reduction and fossil fuel savings is also studied. The energy and exergy efficiencies of the heliostat used in concentrating solar radiation onto the photovoltaic thermal system are 90% and 89.5% respectively, while the hydrogen production from the two multigeneration system configurations is 10.6 L/s. The concentrated photovoltaic thermal system has a 74% energy efficiency and 45.75% exergy efficiency, while the hot air production chamber has an 85% and 62.3% energy and exergy efficiencies, respectively. Results from this study showed that the overall energy efficiency of the multigeneration system increases from 68.73% to 70.08% with the integration of the Kalina system. Also, an additional 417 kW of electricity is produced with the integration of the Kalina system and this justifies the importance of the configuration. The production of hot air at the condensing stage of the photovoltaic thermal/Kalina hybrid system is integral to the overall performance of the system.

The prediction accuracy of support vector regression (SVR) is highly influenced by a kernel function. However, its performance suffers on large datasets, and this could be attributed to the computational limitations of kernel learning. To tackle this problem, this paper combines SVR with the emerging Harris hawks optimization (HHO) and particle swarm optimization (PSO) algorithms to form two hybrid SVR algorithms, SVR-HHO and SVR-PSO. Both the two proposed algorithms and traditional SVR were applied to load forecasting in four different states of Nigeria. The correlation coefficient (R), coefficient of determination (R2), mean square error (MSE), root mean square error (RMSE), and mean absolute percentage error (MAPE) were used as indicators to evaluate the prediction accuracy of the algorithms. The results reveal that there is an increase in performance for both SVR-HHO and SVR-PSO over traditional SVR. SVR-HHO has the highest R2 values of 0.9951, 0.8963, 0.9951, and 0.9313, the lowest MSE values of 0.0002, 0.0070, 0.0002, and 0.0080, and the lowest MAPE values of 0.1311, 0.1452, 0.0599, and 0.1817, respectively, for Kano, Abuja, Niger, and Lagos State. The results of SVR-HHO also prove more advantageous over SVR-PSO in all the states concerning load forecasting skills. This paper also designed a hybrid renewable energy system (HRES) that consists of solar photovoltaic (PV) panels, wind turbines, and batteries. As inputs, the system used solar radiation, temperature, wind speed, and the predicted load demands by SVR-HHO in all the states. The system was optimized by using the PSO algorithm to obtain the optimal configuration of the HRES that will satisfy all constraints at the minimum cost.

In this study, photovoltaic (PV) technology development over the years is reviewed. The use of PV power plants to solve inadequate power supply in Kurdistan is also analysed. PV power application is one of the most developed renewable energy applications but still not commercialized in somw countries. In this paper, three different locations will be evaluated in Kurdistan for PV plant installation. The research will investigate the best location for PV plant installation in Kurdistan, check the viability of the proposed plants and compare the performance of a fixed and a double axis tracking system. A 10 MW PV plant is developed and simulated based on economic terms. The results from the analysis shows that the simple payback period for a 10 MW PV plant in all the locations considered is between 6.8 and 7.2 years. Also, the installation with two-axis tracking system gave the lowest simple payback period (6.8 years). The PV plant is viable considering other economic indicators like; IRR, NPV, annual life cycle savings and BCR. The yearly savings of the system for one of the locations considered is US$1,573,327 with a dual axis tracking system. ©2019. CBIORE-IJRED. All rights reserved

The main aim of this study is to review researches that have been carried out on solar assisted HVAC systems. The objective is to design a basic solar assisted air conditioning system that ...

Hybrid Renewable Energy Systems (HRESs) have been touted as an appropriate way for supplying electricity to remote and off-grid areas in developing countries, especially in sub-Saharan Africa (SSA), where rural electrification challenges are the most pronounced. This study proposes a two-step methodology for optimizing and analyzing a stand-alone photovoltaic/wind/battery/diesel hybrid system to meet the electricity needs of Fanisua, an off-grid and remote village of northern Nigeria. In the first step, the MATLAB environment was used to run simulations and optimize the system via the genetic algorithm. Then, techno-economic and emissions analysis was carried out in the second step to compare the proposed system to the existing traditional modes of rural electrification in sub-Saharan Africa, namely, the grid-extension and diesel generator. The break-even distance parameter was adopted in the comparison with grid-extension. Besides, the hypothetical project of replacing the diesel generator by the optimal system was analyzed using the Simple Payback Period (SPP) and Net Present Value (NPV) parameters. The resulting optimal design architecture included an 89.271-kW photovoltaic array, a 100.31-W diesel generator, and 148 batteries with a total annualized cost (TAC) and cost of energy (COE) of USD 43,807 and USD 0.25/kWh, respectively. The break-even distance found was 16.2 km, while the NPV and SPP of the hypothetical project were USD 572,382 and 2.8 years, respectively. The savings in carbon dioxide (CO2) emissions of the proposed system compared to the grid extension and the diesel generator were found to be 85,401.08 kg/year and 122,062.85 kg/year, respectively. This study highlighted the role that solar PV-based HRESs could play in the sustainable electricity supply in rural areas of sub-Saharan Africa.

This research designed a multigeneration system that meets the energy requirement of a rural community in Nigeria. This system is powered by the biogas produced from maize silage and chicke...

A novel multi-generation system (MGS) that comprises two absorption cycles, two Rankine cycles (RCs), and a hot water (HW) production chamber is studied in this research. It is designed to utilize the waste heat from the first Rankine cycle as a thermal energy input for the second Rankine cycle and a double-effect absorption cycle (DEAC). The waste heat from the second Rankine cycle serves as heat input to a single-effect Rankine cycle. Regeneration and reheat principles are also applied to the Rankine cycles. The objective of the study is to develop an MGS without a gas cycle that can achieve higher energy and exergy efficiencies. Two concentrated solar technologies, namely, parabolic trough collectors (PTCs) and heliostats are used to power the designed system. The environmental benefit of the system is also analyzed. The energy and exergy efficiencies of the novel MGS presented in this study are 73.11% and 50.72%, respectively. The application of solar thermal technologies to power the system reduces the overall energy and exergy efficiencies, respectively, to 56.12% and 38.39% for the solar PTC and 41.89% and 29.06% for heliostats. The energy and exergy coefficient of performances (COPs) are 0.754 and 0.349 for the single-effect absorption cycle (SEAC), respectively. As much as 752.7 kg/h of CO2, 2.13 kg/h of NOx, and 4.21 kg/h of SOx will be saved from being emitted to the atmosphere.

In light of the popular gain of renewable energy sources and solar energy technologies in particular, photovoltaic thermal systems present an interesting approach towards cogeneration of electricity and heat. The extraction of heat from the photovoltaic array for use also serves the purpose of reducing the operating temperature of the solar cells to improve their power conversion efficiency. This study analyzes the possibility of incorporating a PV/T system with an absorption system. Three different systems are considered; the single effect, double effect & triple effect absorption systems driven by heat from the PV/T. It is evident that the triple effect absorption cooling system has the highest coefficient of performance thus giving a greater cooling benefit for the same input energy from the PV/T.

Nanofluids have gained tremendous research interests in diverse fields of study due to their improved properties, especially as heat transfer fluids. Numerous studies have revealed the characteristics, limitations, and applicability of single type nanoparticles and the attributes of their colloidal mixtures. The discovery of the synergistic effect of nanoparticles, as relating to their improved thermophysical properties have been further explored in experimental and numerical studies of hybrid nanofluids. While the major focus has been on thermal conductivity, and viscosity, another extremely important property that gets little study attention is the specific heat capacity, which is a key thermal property in energy systems. Proper understanding of the specific heat capacity (SHC) of hybrid nanofluids is a sine qua non for proper decisions for heat transfer and heat storage applications. The crux of this review study is to give a detailed and comprehensive review of the specific heat capacity of hybrid nanofluids. The synthesis, characterization, and stability of hybrid nanofluids are presented. Furthermore, the different effects like temperature, volume concentration, mixture ratio, and particle size that influence the SHC behaviour of hybrid nanofluids are analyzed in this study. A compilation and discussion on correlation and machine learning models developed for hybrid nanofluids are also presented. Results suggest that volume concentration have an inverse relationship with the SHC of hybrid nanofluids, an increase in temperature improves the SHC of hybrid nanofluids, and this is more significant at temperatures above 50 ℃. Finally, although scarcely researched, the SHC is also affected by the size of the nanoparticles.

The utilization of solar thermal collectors has increased significantly in the last decade. The heat transfer fluids that is used in the design of these systems has notable effects on their performance. The recent discoveries of hybridized nanofluids, give a promising approach for investigating the performance of parabolic trough collectors (PTC), especially at different design conditions and environmental parameters. This study investigates the thermodynamic performance of a Kalina cycle incorporated with a parabolic trough collector that utilizes ternary nanofluid as a heat transfer fluid. The use of mono, hybrid and ternary nanofluids (THNF) in the parabolic trough collector is examined based on their impact on the efficiency of thermal system. The nanofluids considered are Al2O3, Al2O3–Fe, Al2O3–ZnO, and CuO–MgO–TiO2. The performance of integrated cycle based on the effect of solar irradiation and volume fraction of the nanofluids are studied and compared with conventional fluids namely: thermal VP1 oil, DowThermal oil, and Salt (7NaNO3, 40NaNO2, 53KNO2). In addition, an optimization study is conducted using genetic algorithm to maximize the net power output of the Kalina cycle and the exergetic efficiency of overall system. The results showed that performance of the system which uses nanofluids as a working fluid was higher than the systems using conventional fluids. Furthermore, the results demonstrate that maximum net power output of the system is recorded when Al2O3, Al2O3–Fe, Al2O3–ZnO, and CuO–MgO–TiO2 nanoparticles are used. The power outputs were evaluated as 59.72 kW, 56.64 kW, 54.54 kW, and 61.21 kW respectively. The optimization study reveals that the optimum exergetic efficiency when Al2O3, Al2O3–Fe, Al2O3–ZnO, and CuO–MgO–TiO2 nanofluids are used can reach up to 21.0%, 17.2%, 10.8%, and 25.1% respectively.

Agriculture and its corresponding farms are an integral part of every society/country. In recent years, the energy consumption by farms has risen as sophisticated technologies (that require a high amount of energy) are used for the pre-processing/storage of farm produce. In a bid to advance the transition toward cleaner energy consumption in farms, the thermodynamic assessment of two innovative high-performance solar-based multigeneration systems is presented in this study. Based on the identified most crucial energy needs in farms, the multigeneration systems are designed to produce electrical power, cooling/refrigeration effect, hydrogen, and domestic hot water. In comparison to existing literature, this study is novel as it analyzes the daily performance of the multigeneration systems based on the integration/comparison of two storage techniques. While thermal storage is integrated with one multigeneration system (MGS-TS), the power-to-hydrogen conversion and use of the hydrogen in a solid oxide fuel cell is considered as the storage mechanism in the second system (MGS-SOFC). To analyze the daily performance of the systems, solar parabolic trough collectors are used to produce the input thermal energy based on a 6-hour availability timeframe per day, and the storage systems are designed to power the system for the remaining 18 h. The multigeneration systems developed are analyzed using the energy/exergy approach while the economic costs of the systems are also compared. The effect of different crucial parameters including, ambient temperature, discharge periods, dispatch rates, etc. on key variables related to the systems is investigated. Based on the performance assessment of the two high-performance systems modeled in this study, the overall energetic and exergetic efficiencies are 55.37% and 53.70% for MGS-TS, and 51.12% and 46.82% for MGS-SOFC. The total daily electricity, cooling/refrigeration effect, and hot water useful outputs from the two multigeneration systems are 61,630 kWh/day, 7,939.1 kWh/day, and 125,178 Liters/day for MGS-TS; and 34,597 kWh/day, 15,504 kWh/day, and 129,686 L/day for MGS-SOFC respectively. While the performances of the two systems differ slightly, the unique advantages of each are embedded in their useful energy products.

In this research, a novel trigeneration powered by a renewable energy (RE) source is developed and analyzed. The trigeneration system is designed to produce electricity, hot water, and cooling using two steam cycles, a gas cycle, hot water chamber, and an absorption cycle. The RE source considered in the scope of this study is biogas generated from chicken manure and maize silage. The energy and exergy analysis of the trigeneration system is performed with the aim to achieve higher efficiencies. The efficiencies are presented based on power generation, cogeneration (electricity and cooling) and trigeneration. The overall trigeneration energy and exergy efficiency for the system developed is 64% and 34.51%. The exergy destruction within the system is greatest in the combustion chamber.

The world has not been able to achieve minimum greenhouse gas emissions in buildings’ energy consumptions because the energy and emissions optimization techniques have not been fully utilized. Thermal comfort is one of the most important issues for both residential and commercial buildings. Out of the 40% of global energy consumed by buildings, a large fraction is used to maintain their thermal comfort. In this study, a comprehensive review of the recent advancements in building energy conservation and efficiency application is presented based on existing high-quality research papers. Additionally, the retrofit of the heating/cooling and hot water system for an entire community in Cyprus is presented. This study aims to analyze the technical and environmental benefits of replacing existing electric heaters for hot water with heat pump water heating systems and the use of heat pump air conditioners for thermal comfort in place of the existing ordinary air conditioners for space heating and cooling. One administrative building, 86 apartments (including residential and commercial) buildings, and a restaurant building is retrofitted, and the feasibility of the project is determined based on three economic indicators, namely; simple payback period (SPP), internal rate of return (IRR), and net present value (NPV). The electrical energy required by the hot water systems and the heating/cooling system is reduced by 263,564 kWh/yr and 144,825 kWh/yr, respectively. Additionally, the retrofit project will reduce Cyprus’ CO2 emission by 121,592.8 kg yearly. The SPP, IRR, and NPV for the project show that the retrofit is economically feasible.

The main aim of this article is to examine the feasibility of an energy audit program. LEDs are used to replace the sodium vapor lamps and high-pressured mercury vapor lamps that are currently used for the street lighting system in the Turkish Republic of Northern Cyprus. 44% of the fossil fuels imported into the Turkish Republic of Northern Cyprus is used for electricity generation, which makes the reduction in the consumption of electicity very important. This project will save as much as 36,880,410 kWh on site annually and 111,758,818 kWh from the source. The economic, environmental, and fossil fuels savings of this project are also evaluated.

One of the main challenges in renewable energy integrated multigeneration and comprehensive system researches is the inability to study the transient performance analysis of the system. In this study, a novel wind-biomass comprehensive energy system for power, cogeneration, trigeneration, and multigeneration is proposed. This system is analyzed in both steady-state and transient conditions using energy and exergy approaches. Rice husk is considered as the raw material for biomass fuel. The comprehensive system is modeled to produce electricity, freshwater, hot water, and hydrogen with a steam cycle, an organic Rankine cycle, a double stage refrigeration system, a proton exchange membrane electrolyzer, and a hot water chamber. Electric vehicles are integrated with the system in time-based process modeling to ensure load stability and maximize electricity production. The overall exergy and energy efficiencies of the proposed comprehensive system increase from 24.91% and 27.42% while producing electricity to, 26.08% and 35.22% when multigenerating. Based on the transient analysis, this system is capable of meeting the energy demand of a rice-producing factory, campus, and its surrounding community. The process modeling also shows the hourly performance of the system and its load stability.

One of the challenges faced by renewable energy (RE) powered multigeneration system is the unavailability of RE resources at different times. In this research, a novel comprehensive energy system powered with wind turbines, concentrated photovoltaic/thermal and biogas is modelled and analyzed using energy and exergy approach. Multiple useful products such as electricity, hot air, hydrogen, fresh water, cooling effect and hot water will be produced by the system. Four different operational scenarios namely; CPVT/wind, wind/biogas, CPVT/biogas, and biogas only are considered for this comprehensive energy system. Thermal energy storage is incorporated with the system, in order to save thermal energy that will be used during hours without solar radiation. Furthermore, the CO2 emissions saved, in comparison with the use of different fossil fuel sources is analyzed. The maximum productions from the comprehensive system are: 3.4 MW of electricity; 12.41 L/sec of Hydrogen; 279.4 kW of cooling effect; 17.546 kg/s of hot air; 144.18 L/min of hot water and 10.31 L/min of fresh water. The overall energetic efficiency of the system considering all the case studies ranges from 64.91% to 71.06% while the exergetic efficiencies ranges from 31.80% to 53.81%. The CO2 emission analysis results show that the system is environmentally friendly.

Unit Commitment (UC) requires the optimization of the operation of generation units with varying loads, at every hour, under different technical and environmental constraints. Many solution techniques were developed for the UC problem, and the researchers are still working on improving the efficiency of these techniques. Particle swarm optimization (PSO) is an effective and efficient technique used for solving the UC problems, and it has gotten a considerable amount of attention in recent years. This study provides a state-of-the-art literature review on UC studies utilizing PSO or PSO-variant algorithms, by focusing on research articles published in the last decade. In this study, these algorithms/methods, objectives, constraints are reviewed, with focus on the UC problems that include at least one of the wind and solar technologies, along with thermal unit(s). Although, conventional PSO is one of the most effective techniques used in solving UC problem, other methods were also developed in literature to improve the convergence. In this study, these methods are grouped as extended PSO, modified PSO, and PSO with other techniques. This study shows that PSO with other techniques are utilized more than any other methods. In terms of constraints, it was observed that there are only few studies that considered Transmission Line (TL), Fuel (F), Emission (E), Storage (St) and Crew (Cr) constraints, while Power Balance (PB), Generation limit (GL), Unit minimum Up or Down Time (U/DT), Ramp Up or Ramp Down Time (R-U/DT) and system Spinning Reserve (SR) were the most utilized constraints in UC problems considering wind/solar as a renewable source. In addition, most of the studies are based on a single objective function (cost minimization) and, few of them are multi-objective (cost and emission minimization) based studies.

Due to environmental and economic drawbacks of fossil fuels, global renewable energy (RE) capacity has increased significantly over the last decade. Solar photovoltaic (PV) is one of the fastest-growing RE technologies. Selecting an appropriate site is one of the most critical steps in utility-scale solar PV planning. This paper aims at proposing a rational multi-criteria decision-making (MCDM) approach based on the Brown&ndash, Gibson model for optimal site selection for utility-scale solar PV projects. The proposed model considers the project&rsquo, s net present value (NPV) along with seven suitability factors and six critical (constraint) factors. The RETScreen software was applied in calculating the NPV, the simple payback period and the carbon emission savings of the project at each alternative site. The weights of the suitability factors were determined using the analytical hierarchy process. Applied to the case study of finding the best location for a 5 MW solar PV project in northern Cameroon, the optimization results showed that Mokolo was the optimal location. The sensitivity analysis results revealed that the rankings of alternative sites based on the project&rsquo, s NPV and the proposed model are not consistent. Compared to the traditional MCDM approaches, the proposed model provides decision-makers with a more practical thinking method in the optimal location process of utility-scale solar projects.

In this study, a solar assisted multi-generation system is presented. The exergy and energy performance analyses are the objective of this research. The multi-generation system consists of two Rankine cycles, two absorption cycles and a hot water tank. Solar parabolic trough collectors are used to generate thermal energy from the Sun which in turn is used to power the system. The multi-generation system achieves an energy and exergy efficiency of 77% and 49%, respectively without solar input. Considering the solar PTC, the efficiencies respectively are 57% for energy and 40% for exergy. The COPs for the absorption cycle and other findings from the study are presented in details in the full paper. Exergy destruction in major components is calculated and parametric studies are done to check the performance of the system under varying global solar irradiance conditions.

The objective of this work is to examine and compare the techno-economic and environmental feasibility of 40MW photovoltaic (PV) power plant and 40MW parabolic trough (PT) power plant to be installed in two different cities, namely Nicosia and Famagusta in Turkish Republic of Northern Cyprus (TRNC). Long term solar radiation and sunshine data for Nicosia and Famagusta are considered and analysed to assess the distribution of solar radiation, sunshine duration, and air temperature. In addition, these two different technologies with same rated power of 40MW will be compared with the performance of the proposed Solar Power Plant at Bari, Italy. The project viability analysis is performed using System Advisor Model (SAM) through Annual Energy Production and economic parameters for both cities. It is found that for the two cities; Nicosia and Famagusta, considered through this study, the PT plants produce more energy than PV plant. It is also observed that installation of the PT system near an existing steam turbine power plant will make the investment more feasible if the steam produced by the PT system is used to run the steam turbine power plant. The high temperatures that are used to produce steam for the turbines in the PT plant system can be supplemented with a secondary plant based on natural gas or other biofuels and can be used as backup. Although the initial investment of PT plant is higher, it has higher economic return and occupies smaller area compared to PV plant of the same capacity.

BACKGROUND One of the main causes of diabetic neuropathy is endoneurial edema, which increases the internal pressure of the perineurium, which has a tight structure. The treatment used to reduce internal pressure is perineurotomy, in which a surgical incision is made into the perineurium. METHODS Forty male Sprague-Dawley rats were used in the study. They were classified into four groups. Streptozotocin-induced diabetes was created in groups III and IV. The sciatic nerve was transected and repaired epineurally in all groups. Perineurotomy was performed additionally in group II and IV to the sciatic, peroneal, tibial, and sural nerves from the most proximal side to their most distal ends. The sciatic function indices were calculated for functional assessment. Light and electron microscopic evaluations were performed for morphometric assessment. In addition, the myelinated and degenerated fibers were counted in all groups. RESULTS The sciatic function indices of the diabetic perineurotomy group were found to be significantly higher than those of the other groups (p < 0.05). Based on the myelinated fiber counts, there was insignificant difference between group I and group II, whereas the difference was significant (p < 0.05) between group III and group IV. Presence of peripheric nerves in light microscopic evaluation revealed normal characteristics of myelinated fibers in group I and group II. The myelinated axon profile in group IV was similar to that of groups I and II in electron microscopic evaluation. CONCLUSION It is concluded that perineurotomy may be established as a useful adjunctive procedure for nerve repair in diabetic patients.

The dependence of J-R curves on size of test piece is examined for fully plastic deep notch bend (DNB) tests on HY130 steel, taken to large amounts of ductile crack growth (60 per cent of the ligament) for a range of initial widths at 20 mm thick and one geometrically similar size, 50 mm thick. The object is to understand the cause of the widely different patterns of behaviour that have been reported in the literature, even within the DNB type of configuration. In the present tests, the proportion of shear lip is the same for the geometrically similar pair but the J-R curve for the 50 mm thick piece is much lower than for the similar piece, 20 mm thick. The rate of change of displacement, dq/da, is analysed using the factor. r∗, that defines the instantaneous centre of rotation at each step of growth, to give a measure of crack tip opening angle (CTOA), xg. After an initial transient regime of small growth, xg and r∗ remain constant. The normalized load. L, rises due to work hardening during crack growth by amounts that depend on size while xg and r∗ vary mildly with initial width to give an appreciable variation of the combined term Lxg/r∗, which is the factor that controls the behaviour of the JR curves. It is speculated that CTOA and its variation with configuration (as seen in the literature) may, for large growth, assume the role of the two parameters suggested in recent literature as controlling the variation of toughness with constraint.