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.
Concentrated research topic in the study of variables key to the work of offices of inspectors Amyin ، a (re- design function، and performance Organisational ) and took this message to know the nature of the relationship and the impact of the dimensions of the re- design function as a variable interpretative through its dimensions، is ( the diversity of skill، selecting the task ، the importance of task، autonomy، feedback )، and performance Organisational variable responsive through two dimensions are ( effectiveness ، efficiency )، and in order to test the research hypotheses were absorbed variables in the form of a questionnaire and were questionnaire primary means of gatheri
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Statistics indicate criminal in most countries of the world that the suicide rate continues to increase, as it prevalence manufacturing and complexity of life and the intensification of conflicts and escalating problems of rising suicide rates. And suicide is death intentional, that is, the intentional act that leads to ending the life of the individual and self-on purpose. The current research aims to identify the suicide in terms of its causes and its factors and come up with recommendations for the prevention of suicide. Because suicide is a life-threatening problem has tried several theories of interpretation and stand on its grounds. Considering the theories of psychoanalysis (Freud) that suicide is the result of the individ
... Show MoreAesthetic performance in the mobile sculptures
Ali Abd Almohsen Ali
Abstract
Chapters of this research are discussed one of the turning points in the In the history of sculpture, which sparked a debate in artistic circles, namely the introduction of the actual movement in sculpture . The researcher highlighted on one of the corners of the controversy on this subject for discussion and looking in and Found results contribute to answer some questions . the Beginning been allocated to the statement of this Research Methodology , research problem, and its importance, and its goal, and borders , the main problem is Lack of clarity of the concept of real motion (physical) in the sculpture , And how the audience understand the aspects
The current research focuses on a major problem: the weak role of disclosing corporate information in the application of laws, regulations and instructions related to the application of corporate governance principles weakens the ability to protect the rights of shareholders and investors in companies listed on the Iraqi Stock Exchange and the study aims to study and analyze the role of disclosure and transparency in achieving the necessary protection to ensure the rights of shareholders. The study was applied to a sample of (42) analysis samples representing (84%) of the total questionnaires distributed to investors and shareholders in all listed companies in the Iraqi Stock Exchange. The results confirm the shareholder's right to obtai
... Show Moren this study, Cr−Mo−N thin films with different Mo contents were synthesised via closed field unbalanced magnetron sputtering ion plating. The effects of Mo content on the microstructure, chemical bonding state, and optical properties of the prepared films were investigated by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and ultraviolet-visible spectrophotometry. XRD results determined the face centered cubic (fcc) structure of pure CrN film. The incorporation of molybdenum (Mo) in the CrN matrix was confirmed by both XRD and XPS analyses. The CrMoN coatings demonstrate various polycrystalline phases including CrN, γ-Mo2N, Cr with oxides layers of MoO3, CrO3,
... Show MoreIn this study, generation of elliptical gears with different teeth profiles of crowned involute, double circular arc (DCA), and combined (crowned involute with DCA) has been developed. The resulting mathematical equations have been computerized and feed to CNC end mill machine to manufacture elliptical gear models with different profiles. These models are investigated in plane polariscope to show the resulting stresses under certain load. Comparison of photo-elastic stress results shows that combined elliptical gears with DCA side as a loaded side have a minimum resulting contact stress with a reduction percentage of 40% compare with contact stresses in counterpart elliptical gear of involute profile (which is commonly u
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This study deals with the aircraft wing analysis (numerical and experimental) which subjected to fatigue loading in order to analyze the aircraft wing numerically by using ANSYS 15.0 software and experimentally by using loading programs which effect on fatigue test specimens at laboratory to estimate life of used metal (aluminum alloy 7075-T651) the wing metal and compare between numerical and experimental work, as well as to formulate an experimental mathematical model which may find safe estimate for metals and most common alloys that are used to build aircraft wing at certain conditions. In experimental work, a (34) specimen of (aluminum alloy 7075-T651) were tested using alternating bending fatigue machine rig. The t
... Show MoreIn this study, Cr−Mo−N thin films with different Mo contents were synthesised via closed field unbalanced magnetron sputtering ion plating. The effects of Mo content on the microstructure, chemical bonding state, and optical properties of the prepared films were investigated by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and ultraviolet-visible spectrophotometry. XRD results determined the face centered cubic (fcc) structure of pure CrN film. The incorporation of molybdenum (Mo) in the CrN matrix was confirmed by both XRD and XPS analyses. The CrMoN coatings demonstrate various polycrystalline phases including CrN, γ-Mo2N, Cr with oxides layers of MoO3, CrO3
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Conservative pipes conveying fluid such as pinned-pinned (p-p), clamped–pinned (c-p) pipes and clamped-clamped (c-c) lose their stability by buckling at certain critical fluid velocities. In order to experimentally evaluate these velocities, high flow-rate pumps that demand complicated fluid circuits must be used.
This paper studies a new experimental approach based on estimating the critical velocities from the measurement of several fundamental natural frequencies .In this approach low flow-rate pumps and simple fluid circuit can be used.
Experiments were carried out on two pipe models at three different boundary conditions. The results showed that the present approach is more accurate for est
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