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A theoretical study of a conventional boost converter is presented. Based on the real behavior of the components, two models of the boost converter are introduced: one dealing only with losses through inductor and capacitor and another taking into account switching losses in addition to resistive ones. From these two models, the detailed analytical expressions of both voltage gain factor and conversion efficiency are established taking into account the losses through parasitic resistances and switching losses. The behavior of the converter is then analyzed for each model by simulation for the voltage gain factor and the conversion efficiency.

Power output from the PV module changes continuously with time depending upon the climatic condition. This changes are most important in tropical area like Senegal due to the variation of the seasons (dry and rainy). Furthermore, different types of maximum power point tracking (MPPT) algorithm are presented in literature in order to get maximum output from the PV system. They can be summarized in two categories: classical and intelligent methods. The classical methods in no uniform weather condition are not efficient and an important loss of energy is showed. However, faced to this problematics like energy loss and no uniform weather conditions an Adaptative methods is used to optimize the PVs energy. In this study, two intelligent controllers based on artificial neural networks (ANN) and Adaptive Neuro Fuzzy Inference System (ANFIS) are proposed to optimize the PVs production in non-uniform weather conditions and compared in order to show the most powerful model. For the ANN, the main challenge is to find the optimal neural in the hidden layer and in the paper, it is obtained using evaluator factor like mean squared error (MSE). These techniques using artificial intelligence (AI) algorithms are used for power optimization of a photovoltaic system are trained and validated with real data from a photovoltaic micro power plant in dry and rainy season installed at polytechnic high school of Dakar. The performances of the controllers to optimize the PVs power are evaluated during the dry and rainy seasons. Simulation results show that the ANFIS MPPT controller is more efficient and robust than ANN in non-uniform weather conditions. They have the ability of generalization and adaption to each meteorological conditions. These bullet summarize the applied methodology•A real electrical characteristics of photovoltaic panel are used for learning and validation of the controllers.•A comparative study of the methods in two different season is done.•ANFIS gives best performance in weather conditions compared to the ANN.

Biogas production from crops and their residues is widely used as feed because of its availability and high methane content due to its calorific value. The aim of this study is to estimate the response of cereal crops such as maize, sorghum, wheat, barley and rice to elevated temperature and his impact on biogas production by meta-analysis method. Studies show that increasing temperature by 1°C and 2°C respectively decreased biomass yield by -5% to -7% (wheat), -5% to -16% (rice), -7% to -12% (sorghum), -10% to -14% (maize) and -4% (barley). On the other hand, key element which determine the quality of the plant and which are negatively affect by elevated temperature are the basic elements for a good quality and quantity of biogas such as ( lipids, carbohydrates, micro and macro-element). If protein concentration increases under warming, decrease in grain is largely due to lower starch concentration under elevated temperature, -13 to -33% for barley, -2 to -33% for wheat and -2 to -6% for rice. Lipids also decrease under elevated temperature and some nutrients like Selenium (Se), Cobalt (Co) and Aluminum (Al) which decrease respectively by -43.5%, -15% and -22%. Based on these results, we can argued that biogas production from cereal crops is threatened in the future.

This work presents an experimental study of H20-NH3-H2 diffusion absorption refrigeration under two types of energy sources, i.e. the conventional electric energy from grid (electric) and exhaust gas from internal combustion engine. Dynamic method is used to evaluate the behavior of the components of the system for both energy sources. Results obtained show that the performance of each component under different types of energy sources is almost coherent. For the generator, the electrical heater system requires more time to warm up, around three minutes, compared to the 40 s for system running with exhaust gas. For the evaporator, the decreasing rate is higher for the exhaust gas source and it took only about two hours to reach steady-state while for the electrical heat, the steady-state is reached after about seven hours of operation. For both energy sources, the evaporation temperature stabilizes to 3 °C and the minimum temperature to boil off ammonia is around 140 °C.

Abstract This paper presents an investigation of the energy consumption due to domestic hot water (DHW) production in large buildings. We have studied three types of reference buildings: one office, one residence and a 3-star hotel located in Senegal. The DOE2.1E (the building energy program of the Department of Energy Version 2.1E) has been used. One of its main advantage is that it allows to take into account both energy end use categories and a great number of parameters of the building energy performance. Four climatic regions have been identified and their equivalent “standard” conditions are all defined. Those conditions are the same as the current design and operating conditions of each type of building. The DHW energy consumption is calculated and compared with the total energy generated by all end uses (lighting, cooling/ventilation, DHW, and other equipment). Before we carry out wide and systematic simulations of the three buildings energy performance, we pay special attention to check and validate the DHW part of the DOE2.1E model. There was an agreement between the recorded monthly DHW energy load on the one hand, and on the other the computed results. We end up finding results that could open new perspectives for building a strategic methodology to provide guidelines for DHW energy saving measures in large buildings in West Africa. Furthermore, it is expected that energy researchers concerned about energy and environmental efficiency would consider this study for promoting CO 2 emission reduction in relation with DHW production in large buildings.

This paper investigates theoretically the behavior of the space charge region of a silicon solar cell and its associated capacitance under the effect of an external electric field. The purpose of this work is to show that under illumination the solar cell’s space charge region width varies with both operating point and the external induced electric field and how the solar cell capacitance varies with the space charge region width. Based on a 1D modelling of the quasi-neutral p-base, the space charge region width is determined and the associated capacitance is calculated taking into account the external electric field and the junction dynamic velocity. Based on the above calculations and simulations conducted with Mathcad, we confirmed the linear dependence of the inverse capacitance with space charge region width for thin space charge region and we exhibit an exponential dependence for large space charge region.

Cette étude a été réalisée dans le bassin arachidier du Sénégal, caractérisé par un système de rotation céréales/légumineuses en agriculture pluviale. Elle visait à analyser l’impact des équipements utilisés dans les exploitations agricoles sur les rendements des cultures. La méthodologie utilisée repose sur des enquêtes auprès de producteurs et des analyses économétriques de type log linéaire. Les résultats ont révélé un sous-équipement des exploitations agricoles dans le système pluvial. Le niveau actuel de mécanisation des exploitations a un effet positif sur la productivité de la terre mais les accroissements de rendement sont faibles et insignifiants pour l’arachide, le mil et surtout pour le maïs. L’étude a mis en évidence que, le niveau d’équipement actuel des exploitations, même doublés, ne favorise pas un accroissement significatif des rendements à l’hectare des différentes cultures dans le bassin arachidier. Cette étude renforce l’argument selon lequel, l’optimisation de l’équipement des exploitations agricoles en matériels agricoles joue un rôle déterminant dans l’expression du rendement et au final dans la productivité agricole.