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.
Day after day, Morsek literature 879-1018/1492-1609proves the completion of all literary branches starting from poetry with its different purposes to include prose with its various subjects. In 2016, a complete text of ‘the literature of Morsek journey
Resumen
Este trabajo de investigación ofrece uno de los temas relevantes en la lengua, el cual es estudiar las dimensiones sintácticas, semánticas y pragmáticas de las preposiciones, en general, y de las dos preposiciones "Para" y "Por" en concreto, en una unidad linguística más amplia que la llamada "Oración". En la parte referida al estudio de las dos preposiciones mencionadas, estudiamos sus distntos usos funcionales, usos que se acercan, unas veces, entre sí y se alejan en otras.
Abstract
... Show Moreتمثل هذه النقوش طبيعة العصر فيه ؛ لذلك نجد الباحثين المهتمين بعلم اآلثار ، والتاريخ القديم هم أكثر من بحث عنها ، ثم حاولوا فك رموزها ، وما زال بعضها قيد الدراسة .
جمعت 50 حية مائية Natrix tessellata على وجبتين الأولى 25 حية عند فصل الربيع تحديدا من منتصف آذار الى منتصف نيسان، اما المجموعة الثانية ، 25 حية لفصل الصيف من منتصف حزيران الى منتصف تموز. اذ عزلت الذكور عن الإناث و حللت قطع من لحم الذكر و قطع من
Prince Kikaus explained to us Conditions of writing and establishing .Then he touched upon the Conditions of the ministry and qualities that must be characterized Author and minister both need machines must be availabla in person if given these positions .he was creative in presenting his ideas which is not without judgment an knowledge.He had a distinct style in mentioned professions and administrative hierarchy As explained in his speech About the writer and his Correspondence and construction and writer position who has developed into a minister then he touched it to the cabinet system and what the minister should do.of qualities .and the importance of the post of minister who mentioned several points to him ou
... Show Moreيعد الربط بين جدلية ما هو كائن وما يجب أن يكون فيما يتعلق بمكانة القوة في المدرك الاستراتيجي الأمريكي وإشكالية توظيفها، من المتلازمات الذهنية الراسخة في التفكير الاستراتيجي الأمريكي، لاسيما بعد أحداث 11 أيلول 2001 وحربي أفغانستان والعراق، والتي كانت من المحفزات الأساسية للبحث عن توظيف بدائل أو وسائل فاعلة تعزز مخرجات الأداء الاستراتيجي الأمريكي بما يصب في المحصلة النهائية في جانب تكتيل القدرات الاستراتيجية
... 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 people of the house (peace be upon them) had several owners who adopted their correct approach and broadcast the Prophet's narrations and narrated it. They were one of the most important media tools in the era that helped spread the thoughts of the people of the house and spread them among the people. Al-Hasan (peace be upon him) and Sunati to mention in this research, we will discuss his life, his love for the people of the house (peace be upon them) and the most important talk that he narrated about the people of the house (peace be upon them(.
قال احد المربين ( أعطوني طفولة سعيدة ممتلئة وخذوا شباباً ناضجاً سليماً) ويعني بالطفولة السعيدة تلك الطفولة المشبعة بالحب والحنان وتلبية الحاجات المهمة للطفل حيث يتعلم الطفل من احضان العائلة بعض النواهي والاوامر حتى اذا اتسعت دائرة معارفه شملت الرفقة والعصبة حيث يبدأ الطفل بالتحرر شيئاً فشيئأ من الضوابط العائلية وينتقل مركز ولائه واخلاصه من العائلة الى العصبية وكلما تتوسع علاقات الطفل تزداد خبراته وت
... Show More