The thermal and electrical performance of different designs of air based hybrid photovoltaic/thermal collectors is investigated experimentally and theoretically. The circulating air is used to cool PV panels and to collect the absorbed energy to improve their performance. Four different collectors have been designed, manufactured and instrumented namely; double PV panels without cooling (model I), single duct double pass collector (model II), double duct single pass (model III), and single duct single pass (model IV) . Each collector consists of: channel duct, glass cover, axial fan to circulate air and two PV panel in parallel connection. The temperature of the upper and lower surfaces of PV panels, air temperature, air flow rate, air pressure drop, wind speed, solar radiation and ambient temperature were measured. The power produced by solar cells is measured also. A theoretical model has been developed for the collector model IV based on energy balance principle. The prediction of the thermal and hydraulic performance was obtained for the fourth model of PV/T collector by developing a Matlab computer program to solve the numerical model. The experimental results show that the combined efficiency of model III is higher than that of models II and IV. The pressure drop of model III is less than that of models I and IV, by (43.67% and 49%). The average percentage error between the theoretical and experimental results was 9.67%.
The aim of this scientific paper is to highlight the effective role of women working in economic development, especially those working in the entrepreneurial sector, which we see as encouraging at the macro-economic level and at the personal level, by highlighting their potential to help them enter the private labour market, value them and empower their role in the economic arena in order to win this bet to become productive and effective workers at all levels.
Through this paper, we will try to highlight the role of Algerian women's contribution to economic development through access to the world of entrepreneurship, and we will also try to find statistics on their success levels at the local and interna
... Show MoreVitamin D receptor (VDR) is a nuclear transcription factor that controls gene expression. Its impaired expression was found to be related to different diseases. VDR also acts as a regulator of different pathways including differentiation, inflammation, calcium and phosphate absorption, etc. but there is no sufficient knowledge about the regulation of the gene itself. Therefore, a better understanding of the genetic and epigenetic factors regulating the VDR may facilitate the improvement of strategies for the prevention and treatment of diseases associated with dysregulation of VDR. In the present investigation, a set of databases and methods were used to identify putative functional elements in the VDR locus. Histone modifications, CpG I
... Show MoreNewspaper headlines are described as compressed and ambiguous pieces of discourse that represent the bodies of the articles. Their main function is to provide the readers with an informative message they would have no prior idea about. Ifantidou (2009) claims that the function of a headline is to get the readers’ attention rather than providing information because it does not have to represent the whole of the article it refers to. This paper aims at examining this hypothesis in relation to scientific news headlines reported by a number of news agencies. The paper follows Halliday (1967) information structure theory by applying it on ten selected headlines; each two headlines represent one scientific discovery reported by different new
... Show MoreThe purpose of the study is to identify the teaching techniques that mathematics' teachers use due to the Brain-based learning theory. The sample is composed of (90) teacher: (50) male, (40) female. The results have shown no significant differences between male and female responses' mean. Additionally, through the observation of author, he found a lack of using Brain-based learning techniques. Thus, the researcher recommend that it is necessary to involve teachers in remedial courses to enhance their ability to create a classroom that raise up brain-based learning skills.
In this paper, an intelligent tracking control system of both single- and double-axis Piezoelectric Micropositioner stage is designed using Genetic Algorithms (GAs) method for the optimal Proportional-Integral-Derivative (PID) controller tuning parameters. The (GA)-based PID control design approach is a methodology to tune a (PID) controller in an optimal control sense with respect to specified objective function. By using the (GA)-based PID control approach, the high-performance trajectory tracking responses of the Piezoelectric Micropositioner stage can be obtained. The (GA) code was built and the simulation results were obtained using MATLAB environment. The Piezoelectric Micropositioner simulation model with th
... Show MoreIn this work a model of a source generating truly random quadrature phase shift keying (QPSK) signal constellation required for quantum key distribution (QKD) system based on BB84 protocol using phase coding is implemented by using the software package OPTISYSTEM9. The randomness of the sequence generated is achieved by building an optical setup based on a weak laser source, beam splitters and single-photon avalanche photodiodes operating in Geiger mode. The random string obtained from the optical setup is used to generate the quadrature phase shift keying signal constellation required for phase coding in quantum key distribution system based on BB84 protocol with a bit rate of 2GHz/s.
In this paper, Bayes estimators of the parameter of Maxwell distribution have been derived along with maximum likelihood estimator. The non-informative priors; Jeffreys and the extension of Jeffreys prior information has been considered under two different loss functions, the squared error loss function and the modified squared error loss function for comparison purpose. A simulation study has been developed in order to gain an insight into the performance on small, moderate and large samples. The performance of these estimators has been explored numerically under different conditions. The efficiency for the estimators was compared according to the mean square error MSE. The results of comparison by MSE show that the efficiency of Bayes est
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