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.
لم يعد تقييم شركات الاعمال يعتمد على ربحيتها فحسب، ولم تعد تلك الشركات تعتمد في بناء سمعتها على مراكزها المالية فقط، فقد ظهرت مفاهيم حديثة تساعد على خلق بيئة عمل قادرة على التعامل مع التطورات المتسارعة في الجوانب الاقتصادية والتكنولوجية والإدارية عبر أنحاء العالم. وكان من أبرز هذه المفاهيم مفهوم "المسؤولية الاجتماعية للشركات" والتسويق الاخضر او المواطنة التسويقية او التسويق البيئي . وقد أصبح دور مؤسسات ال
... Show Moreتعرض الاقتصاد العراقي إلى صدمات نقدية شديدة بسبب الظروف السياسية والاقتصادية غير المستقرة والمتمثلة بشكل أساسي لخوض العراق حرب طويلة الأمد مع إيران في الثمانينات وحربين مدمرتين مع الولايات المتحدة الأمريكية فضلاً عن فرض الحصار الاقتصادي طيلة ثلاثة عشر عاما ً .
وتهدف هذه الدراسة إلى قياس وتحليل الصدمات النقدية التي تعرض لها الاقتصاد العراقي في فترة الثمانينات والتسعينات وبداية هذا القر
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Resumen
La literatura española tiene muchísimos de los grandes personajes y las figuras literarias que casi todos desempeñaron de una forma u otra un eficaz e importante papel en el desarrollo de la literatura española en particular y la literatura universal en general, entre otros podemos mencionar el gran escritor de origen argentino Jorge Luis Borges sobre el mismo gira este trabajo de investigación.
Sinceramente, podemos decir que el objetivo principal de ese trabajo de investigación es hacer conocer de una forma tan sencilla, tan simple y tan clara al lector público quién es Jorge Luis Borges quien procedía de una familia de próceres
... Show MoreSince the early ages, scientists have been keen on the second source of Islamic law, namely the hadith of the Prophet. They also took from the less disciplined narrators, but they chose from their conversations a selection, and for this some prominent narrators who can be considered that Ibn Habban has been hardened to weaken them. Narrators who avoided Ibn Habban novel They are not true because Ibn Habban neglected her and left her to hurt some narrators who are confident in themselves
The phenomenon of Masculine and feminine is one of the important grammatical studies because of their influence on the sentence structure, words come either masculine and feminine type when using one of them in place of the other , this displacement might cause distribution in the sentence itself because,
Abstract
The aim of the present research is to identify the test wisdom and the preoccupation with learning and psychological tension among postgraduate students at the University of Samarra according to the variables of the department, gender, age, and employee or non-employee, and revealing the relationship between the test wisdom and the preoccupation with learning and psychological tension. The research sample consisted of (75) students randomly selected from postgraduate students at the college of Education. The researcher applies test –wisdom of (Mellman & Ebel) and measurement of preoccupation with learning prepared by (Al-zaabi 2013) also, the researcher used the scale of t
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The idea of this research is based on presenting a study specialized with the rules and bases of the Iraqi methodological music composition of the Symphony Orchestra according to the construction of the musical compositions of great forms and which are characterized by the melody difference and variation within their musical fabric according to the method of distributing the instruments and their types within the orchestra. The researcher has been interested in studying this building based on what is written for him according to the stringed instruments arc instruments and bass, which is represented by the cello and the contrabass. It is possible through the analysis of the melody structure features of these instruments and the melody re
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One of the important differences between multiwavelets and scalar wavelets is that each channel in the filter bank has a vector-valued input and a vector-valued output. A scalar-valued input signal must somehow be converted into a suitable vector-valued signal. This conversion is called preprocessing. Preprocessing is a mapping process which is done by a prefilter. A postfilter just does the opposite.
The most obvious way to get two input rows from a given signal is to repeat the signal. Two rows go into the multifilter bank. This procedure is called “Repeated Row” which introduces oversampling of the data by a factor of 2.
For data compression, where one is trying to find compact transform representations for a
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