The design, construction and investigation of experimental study of two compound parabolic concentrators (CPCs) with tubular absorber have been presented. The performance of CPCs have been evaluated by using outdoor experimental measurements including the instantaneous thermal efficiency. The two CPCs are tested instantly by holding them on a common structure. Many tests are conducted in the present work by truncating one of them in three different levels. For each truncation the acceptance half angle (θc) was changed. Geometrically, the acceptance half angle for standard CPC is (26o). For the truncation levels for the other CPC 1, 2 and 3 the acceptance half angle were 20o, 26o and 59o, consequently. A significant difference between the instantaneous thermal efficiency of 3.86× CPC (θc=20o) and 2.32× CPC (θc=26o), and between that for 3.61× CPC (θc=26o) and 2.32× CPC (θc=26o). It's noticed that the difference between the instantaneous thermal efficiency of 2.32× CPC (θc=59o) and 2.32× CPC (θc=26o) is small compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× CPC (26o) was higher than those for other three CPCs. The experimental results show that the maximum thermal efficiency of the full 2.32×CPC (26o) is 0.708, the maximum thermal efficiency of the 3.93×CPC (15o), when it's truncated to 3.84× CPC (20o), 3.61× CPC (26o) and 2.32× CPC (59o) are 0.51, 0.52 and 0.66, respectively. As the concentration ratio decreases from (3.93× to 1×), the thermal efficiency, energy losses and optical efficiency increase from (0.47 to 63), (1.58 to 7.2 K.m2/W) and (0.494 to 0.797), respectively.
A.R. Ammons's Garbage is a unique poem in all measures, starting from the title to the subject matter of the poem. Though it discusses the ecological repercussion of waste management, the long poem is written to shed light on the correlation between language\poetry and garbage. The paper argues that in his examination of language\poetry and garbage as both reflectors of human life and experience, Ammons claims that redemption is possible through both language and garbage by scrutinizing human experience whether low or high, mundane or sacred. This paper tries to examine Ammons's efforts to use the farfetched metaphor of garbage to discuss language and poetry-writing.
After the democratic transformation in 2003 in Iraq, young people waited a lot to take their real opportunity to participate in politics, but most of the laws regulating political and electoral work have been unfair to young people, despite developments in laws and legislation, but opportunities did not allow young people to participate in politics, which was reflected It negatively affected their participation in voting and nomination, and even their assumption of public office and positions, which is why they complained about the ruling class and the political system through protests, or when they refused to vote, and this is reflected in the recent parliamentary elections and low participation rates
The present research aims at identifying the educational problems and psychological problems of distinguished students at the intermediate level. The research sample consists of (246) students who are randomly selected from four distinguished schools (2) in the Karkh\1 and (2) in the Rusafa\2.
The researcher has constructed two scales for measuring the educational and psychological problems. She ensures the psychometric characteristics of the two scales. Alph-Cronbach and test-retest methodsare used to ensure reliability. Some statistical treatments are used to find out the aims of research. These treatments include the one-sample T-test, two independent samples T-test, and the Pearson correlation coefficient. The results show th
... Show More
Abstract
The research addresses the specification table and the extent of its use in developing achievement tests, as well as detects the obstacles to its use through a sample of (120) respondents from the faculty members in some Baghdad schools and colleges. After unpacking and processing the data statistically, the research reached several results: the study sample do not use the test map in the development of their tests, as their percentage reached (82%) and there are no statistically significant differences in the use of the specification table by the sample members according to their place of work or the number of years of experience. The results also revealed the most important reasons that prevent the use
... Show MoreThe internal administrative spaces of the interior designer formed an obsession for their development and for finding solutions and treatments to advance to enhance the state of adaptation for their employees by providing a healthy, appropriate and sound environment for work and production. . The first chapter focuses on laying theoretical foundations to show what health materials are used in the administrative spaces of the training directorates of the Ministry of Education in Baghdad. The second chapter dealt with the knowledge of health materials, their impact and effectiveness in the interior space, and the variables of their functional characteristics and their work in the interior spaces in a way that enhances the development of
... Show More
Which was entitled : Aesthetic and dramatic dimensions of silence in the feature film , and the researcher clearly define after removing the confusion existing in some authorized sources , as for the concept of silence , adopted in this research is : the death of the audio stream , Hence the researcher shed a light on the aesthetic and the dramatic role of silence in the feature film , through the handing of the silent scenes ( absolute silence ) in the film research divided this research into four chapters . This first Chapter includes : methodological framework , which represents the research problem , which came with the following question : what is the mechanism of productive silence to the
... Show More
A piezoelectric cantilever beam with a tip mass at its free end is a common energy harvester configuration. This article introduces a new principle of designing such a harvester that increases the generated power without changing the resonance frequency of the harvester: the attraction force between two permanent magnets is used to add stiffness to the system. This magnetic stiffening counters the effect of the tip mass on the efficient operation frequency. Five set-ups incorporating piezoelectric bimorph cantilevers of the same type in different mechanical configurations are compared theoretically and experimentally to investigate the feasibility of this principle: theoretical and experimental results show that magnetically stiffened harve
... Show More
(13)
(10)
Epoxy resin has many chemical features and mechanical properties, but it has a small elongation at break, low impact strength and crack propagation resistance, i.e. it exhibits a brittle behavior. In the current study, the influence of adding kaolin with variable particle size on the mechanical properties (flexural modulus E, toughness Gc, fracture toughness Kc, hardness HB, and Wear rate WR) of epoxy resin was evaluated. Composites of epoxy with varying concentrations (0, 10, 20, 30, 40 weights %) of kaolin were prepared by hand-out method. The composites showed improved (E, Gc, Kc, HB, and WR) properties with the addition of filler. Also, similar results were observed with the decrease in particle size. In addition, in this study, mult
... Show More
(4)
The research discusses the mechanism for analyzing the salary scale in the public sector through an analysis of grades, their stages, occupants and their financial entitlements, and the extent to which the information obtained for their investment in strategic planning, conducting correction and treatment can be used. The salaries of the employees in them, whose number is (1117) employees, to be a field of research, as the salary structure in it for the year 2019 was analyzed by relying on a number of statistical tools in the analysis process, including the arithmetic circles, upper limits, minimum limits and percentage, and with
... Show More
(4)