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.
Los enunciados interrogativos desempeñan un papel de sumo interés en el habla del ser humano en todo el mundo, además de la gran importancia que desempeñan sus distintos enunciados y partículas en abreviar las oraciones y hacer llegar a nuestro interlocutor nuestra intención con pocas palabras, por eso a través de esta investigación vamos a enfocar la luz sobre uno de sus tipos fundamentales "los enunciados interrogativos directos", a través de un estudio morfológico contrastivo entre el árabe y el español, este fue el principal motivo para elegir este tema.
A pesar de que los enunciados interrogativos directos aparentemente no ofrecen mucha dificultad, pero dominar a dicho tipo de enunciados con todas sus divisiones, sus
أسلوب العطف: دراسة مقارنة بين اللغة العربية والاسبانية
The current research seeks to shed light on the role that social media can play, through the optimal use of it by students, in achieving academic excellence. The most prominent aims that constitute it are:Identifying the social sites most used by students; learning how students interact with the published study material on communication sites and benefit from them to achieve their academic excellence; and knowing the connection between using social media and achieving academic excellence, and the role that these sites play in achieving academic excellence.That incorrect use by students leads to adverse results, and thus affects their academic level. Failure of parents to monitor their student’ use of social media leads
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The research aims to improve the performance of the Directorate of Maysan water by reconciling the objectives of the employees of the directorate with the objectives of the Directorate itself, as well as to identify the strengths and weaknesses in the performance of the Directorate (Leadership - Individuals - Knowledge - Operations - Financial) and presented to experts and arbitrators of specialized, and the researchers have relied on the case study methodology as a descriptive approach is comprehensive analysis, and draws on more than one approach, method and scientific design, has been interviewed a number of experts in the Directorate Maysan's water Identify the weaknesses and strengths of the Directorate, the research has reached a numb
... Show Moreيسلط هذا البحث الضوء على ظاهرة لغوية، والتي يطلق عليها تسمية "التضاد". يبين هذا البحث مفهوم هذه الظاهرة، خصائصها، أنواعها، وأسبابها، في اللغتين الساميتين: السريانية والعبرية. حيث تم اعتماد المنهج المقارن في دراسة هذه الظاهرة اللغوية وتبيان وجوه التشابه واالختالف في ماهية هذا النوع من المفردات، أي األضداد، في اللغتين: السريانية والعبرية. ويشير البحث إلى نوعين من التضاد وهما: التضاد الذي يكون بين مفردتين مستقل
... Show MoreLos enunciados interrogativos desempeñan un papel de sumo interés en el habla del ser humano en todo el mundo, además de la gran importancia que desempeñan sus distintos enunciados y partículas en abreviar las oraciones y hacer llegar a nuestro interlocutor nuestra intención con pocas palabras, por eso a través de esta investigación vamos a enfocar la luz sobre uno de sus tipos fundamentales "los enunciados interrogativos directos", a través de un estudio morfológico contrastivo entre el árabe y el español, este fue el principal motivo para elegir este tema.
A pesar de que los enunciados interrogativos directos aparentemente no ofrecen mucha dificultad, pero dominar a dicho tipo de enunciados con
... Show Moreدراسة تحليلية لترجمة المسكوكات اللغوية في الصحافة الاسبانية.
This paper shed light on castles in Iraq through Othman reign to know their sorts , and studying planning concentrating on the nature of architecture , this is a serious trying to study and important side of military architecture in Iraq with its reasons of building them which had related with political, military , social ,and economical circumstances of country .
المنطق منهجا نقديا - دراسة في قراءة الشكل الجمالي كتاب (المنطق منهجا نقدياً – دراسة في قراءة الشكل الفني) يهتم الكتاب بدراسة التصورات المنطقية في الفنون التشكيلية وهو يقع في اربعة فصول خصص الاول منها لبيان المنهجية والفكرة العامة عن علاقة المعرفة بالقواعد الفكرية والقواعد المنطقية موضحا ذلك في (مدخل عام) وتعلق الفصل الثاني بالمفاهيم المنطقية وما كتبه علماء المنطق في عرض شامل ومكثف تناول فيه المؤلف مفهوم ال
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