In this work, a flat-plate solar air heater (FSAH) and a tubular solar air heater (TSAH) were designed and tested numerically. The work investigates the effect of increasing the contact area between the flowing air and the absorber surface of each heater and predicts the expected results before the fabrication of the experimental rig. Three-dimensional two models were designed and simulated by the ANSYS-FLUENT 16 Program. The solar irradiation and ambient air temperature were measured experimentally on December 1st 2022, at the weather conditions of Baghdad City- Iraq, at three air mass flow rates, 0.012 kg/s, 0.032 kg/s, and 0.052 kg/s. The numerical results showed the advantage in the thermal performance of the TSAH in comparison to the FSAH, represented by better air temperature difference, better heat transfer from the absorber to air, and better thermal efficiency. The TSAH has a higher thermal efficiency than the FSAH by 7 %, 19 % °C, and 22 % at 0.012 kg/s, 0.032 kg/s, and 0.052 kg/s, respectively. The improvement of the thermal characteristics of the TSAH can be referred to as the increment in the heat transfer contact area between the absorber and the flowing air.
There is of great importance to know the values of the optical constants of materials due to their relationship with the optical properties and then with their practical applications. For this reason, it was proposed to study the optical constants of amorphous silicon nanostructures (quantum well, quantum wire, and quantum dot) because of their importance in the world of optical applications. In this study, it was adopted the Herve and Vandamme (HV) model of the refractive index because it was found that this model has very good optical properties for almost all semiconductors. Also, it was carried out by applying experimental results for the energy gaps of these three nanostructures, which makes the results of the theoretical calculations
... Show MoreIslamic periodicals are defined as: publications issued periodically, and containing articles, research, or studies that convey Islamic thought and culture. Islamic periodicals have a prominent place among other types of sources of documentary and non-documentary Islamic information, because they are characterized by the speed of their issuance and the modernity and diversity of their Islamic information. This study aims to explain the reality of Islamic periodicals published in Iraq, graphically analyze their bibliographic characteristics and emphasize the importance of their issuance, as well as give a historical overview of the issuance and publication of Islamic periodicals in the Arab world and the world, while presenting examples of I
... Show MoreLanguage is an instrument, a tool of culture and a way of communication between the past and the present. No one can know the treasure of human thought and experience in the fields of history, poetry and prose without language as an instrument of communication between cultures and peoples. Language under this description faces many problems, the most important of which is linguistic globalization, which means the flow rate of the strongest language, which has elements of power, domination and control over other languages. In this article, we consider linguistic globalization as a serious problem faced by every language, and we consider its main shortcomings and advantages and its impact on the language and ways of protecting the Arabic lang
... Show MoreThe research aims to identify the social control among kindergarten department students. In order to achieve the objective of the research, a sample of (400) female students: (200) from Baghdad University / Faculty of Education for women and (200) from Mustansiriyha University / Faculty of Basic Education were chosen randomly.
The researchers designed a tool to measure the social control of the study sample. It was exposed to group of specialists in the educational and psychological sciences, measurement and evaluation. In addition to specialists in kindergartens. Two indicators of validity were used. The Alpha-Cronbach method, Pearson correlation coefficient, and independent samples t-test were used to analyze the c
... Show MoreIn order to get an idea about things closely, we should look at the role of social discipline
in the building of society from civilization cultural viewpoint. The real weigh of the societal
opinion is not measured by the number of its population or its area but the real value lies in its
civilization cultural accumulative experience inherited by the generations, which determine its
distinguished character. That is based upon the social construction in which the methods of
socialization and political, economic, cultural and religious stability and enhance the national
and ethical character of self-realization.
In this research, we try to give an analysis for the obstacles in political economic and
religious social
النشاطات العلمية لفرع الفكر السياسي
The Hbl toxin is a three-component haemolytic complex produced by Bacillus cereus sensu lato strains and implicated as a cause of diarrhoea in B. cereus food poisoning. While the structure of the HblB component of this toxin is known, the structures of the other components are unresolved. Here, we describe the expression of the recombinant HblL1 component and the elucidation of its structure to 1.36 Å. Like HblB, it is a member of the alpha-helical pore-forming toxin family. In comparison to other members of this group, it has an extended hydrophobic beta tongue region that may be involved in pore formation. Molecular docking was used to predict possible interactions between HblL1 and HblB, and suggests a head to tail dimer might f
... Show MoreIn this paper, a four species mathematical models involving different types of ecological interactions is proposed and analyzed. Holling type – II functional response is a doubted to describes the behavior of predation. The existence, uniqueness and boundedness of the solution are discussed. The existences and the stability analysis of all possible equilibrium points are studied. suitable Lyapunov functions are used to study the global dynamics of the system. Numerical simulations are also carried out to investigate the influence of certain parameters on the dynamical behavior of the model, to support the analytical results of the model.