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 numerical response of Chrysoperla mutata MacLachlan was achieved by exposing the larvae of the predators to various densities of dubas nymphs Ommatissus lybicus DeBerg. Survival rate of predators’ larvae and adults emergence increased with increasing consumption . Repriductive response of predator was highly correlated with the amount of food consumed (+0.996).
Abstract
The research aims to identify the role played by the strategic mind of human resources managers in reducing the levels of strategic drift that can face the organization, as the problem of research to overlook the importance of this role in monitoring and follow-up all the changes that may face the organization during the implementation of its strategy, therefore highlights the importance Research in providing a set of solutions to the problems faced by the researched organization and as far as the research variables, the researchers have adopted the descriptive analytical approach in the applied side, as adopted the questionnaire as a main tool for data collection, which was prepared based on a number of ready me
... Show MoreThe research aims to know the effect of investment risks measured by the beta coefficient on the efficiency of stock pricing measured by the pricing error. The research was applied in the banks listed in the Iraq market for the period (2017-2020). That affects the value of the shares of the companies listed in it and the risks associated with it, as the risks are a dynamic process that changes over time depending on the variables that affect the general development of the economy, so these fluctuations should be taken into account to achieve maximizing returns and reducing risks and what is reflected in stock prices in the Iraqi markets Securities, through which the following question was asked: How does investment risk affect the efficienc
... Show MoreThe present study included the effect of chronic exposure for two concentrations of NaC? salt on the biology of fresh water zooplankton species Brachionus calyciflorus (from ^otifera). The concentrations 0.5 , 0.75%o were used for chronic exposure to investigate its effects on the life tables, range of the rate of expectation for further life and reproduction. The rotifer B. calyciflorus was sensitive to salinity and may tried to protect the species by increasing the size (2.22 ind./clutch lor control group and 2.9? for 0.5%o concentration) and number of clutches produced ?.1? clutch/female for control group and 2.9 ' ' ' for 0.75 %0 concentration) beside stimulation the animal to produce the first clutch of eggs earlier? ? small reduction
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Federico Garcia Lorca is considered in european and american literary circles as revolutionary symbol of contemporary literature writer through close association with the concerns of his country and the world, and also through the violent propensity to freedom, emancipation and innovation. This personal multi-talent has a significant impact in the spanish literary movement, in particularly, and in world, in general. If Lorca has andalusia blood, is no stranger to contemporary arab man to read to him, and contemplates his experience analyst and literary critic. This research is serious study of this character. There is no doubt the reader will put in front of many facts about personali
... Show MoreAt atmospheric pressure and at a frequency of 9.1 kHz, a constructed magnetically stabilized tornado gliding arc discharge (MSGAD) system was utilized in this study to generate a non-thermal plasma with an alternating voltage source from 2,4,6,8 to 10 kV. Argon gas was used to generate the arc plasma with an adjustable flow rate using a flow meter regulator to stabilize the gas flow rate to 2 L/min. A gliding plasma discharge is achieved by a magnetic field for the purpose of a planned investigation. The influence of the magnetically stabilized tornado gliding arc discharge parameters such as magnetic field and applied voltage on microscopic tornado plasma parameters was studied. The electron temperature1was measured using a Boltzmann plot
... Show MoreOur research which is under the name "Polarization and Communication mechanism in the formation of green industrial products " The problem of the research focuses in identifying what is polarization and its function mechanisms , by displaying the inventive and creative cases of the designer in how to exploit the industrial products and its recycling process to attract the user and recipient by asserting on the values of beauty of the appearance of the industrial product with the attraction Of the user and the recipient with the new function of that product and how its different from the function achieved by the old product , with consideration of nature and its preservation . The results of the research were as following : The designer e
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The research aims to define the theoretical framework for corporate governance and its mechanisms and shed light on corporate governance in Iraq as well as the theoretical framework for the quality of financial reports and their relationship and the role of corporate governance in activating them. A commercial bank as a sample for the research, and a survey list was prepared to show the extent to which the research sample banks are committed to applying internal governance mechanisms. imposed on them by the local environment, which leads to improving the quality of financial reports for these banks.
The imperative of achieving financial stability has transcended national boundaries, necessitating heightened attention from both researchers and policymakers. Consequently, this article delves into an examination of the impact of government debt and public debt on financial development within the context of Iraq. The study employs monetary policy, interest rate, inflation, and population growth as control variables to prognosticate financial development. Utilizing data extracted from the World Development Indicators (WDI) spanning the period from 1995 to 2022, the study employs the dynamic autoregressive distributed lag (DARDL) approach to scrutinize the associations under investigation. The findings underscore a negative association betwe
... Show MoreIn his masterpiece ’The Prophet’, Kahlil Gibran presents his unwavering faith and passionate belief in the healing power of universal love that brings humans to sublime ideas and elevates their souls and behavior. The current study aims to find out the stylistic devices utilized to represent the concept of love based on the hypothesis that Gibran tends to use certain stylistic effects to convey his meaning. The study adopts Leech and Short’s (2007) framework of stylistic analysis to analyze the lexical items and figures of speech in selected extracts from the book. The findings reveal that Gibran prefers concrete nouns, dynamic verbs, and physical adjectives over abstract nouns, stative verbs, and psychological adjectives to s
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