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.
يرمي الكتاب الى التعرّف على خصائص البحوث المنشورة في مجلة الأستاذ وبيان السمات والمكونات الأساسية للمجلة واعداد كشافات تراكمية متنوعة لها . وجاء الكتاب في خمسة مباحث تناول المبحث الاول الاطار العام للبحث ،وضمَّ مشكلة البحث وأهميته وأهدافه واجراءاته والدراسات السابقة ،وتناول المبحث الثاني الدراسة النظرية وضم التعريف بـكشافات الدوريات ،وبيان أهميتها والتعريف بـ كلية التربية /ابن رشد وبيان أهدافها ،ومن ثم ا
... Show MoreThe legal text in the language of civil law, constitutional law, language of judges, and legal profession is concerned with a legal language and words that are coherently significant
تم ت داول مصطلح الأزمة ا دلولية في السياسية ا دلولية خال القرن التاسع عش ر لتحدي دا ملدة الانتقالية بين السلم والحرب سواء أ دت الأزمة إلى نشوب صراع مسلح أم مت ت ت سويتها بالطرق السلمية، وتع دالأزمة ا دلولية مرحلة مت هيدية ل لحرب وهي ا رملحلة التي يسعى فيها أ طرا فالأزمة إلى إبعاد احتمالية نشوء أ و اندلاع الحرب، فالأزمة ه ي مدة حرجة ومرحلة خطيرة بين وقتي السلم والحرب، إن العلاقات ا دلولية تكاد ت عيشأ زمات متلاحقة ع
... Show MoreAmong the commentators who contributed greatly to explaining the basic rules of civilizations in general and Islamic civilization in particular, Sheikh Muhammad Rashid Rida in his interpretation called (Interpretation of the Wise Qur’an), known as (Al-Manar); Whoever reads the tafsir will notice that it was concerned with explaining the civilized aspects in terms of foundations, methodology, factors of demolition and destruction, and ways to avoid them.
Bohemia AL-Kharab for Salah Salah Which contain 477Paper deal With History of Nathion This Novel Has a different styl from another IraQis Novels, this Novel has no conversation this is the basic reason Which hav this research .
The novel have 3 versions , the first one deal with explain the text in different ways , the second contains the realation ship between the text and the reader .
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The last thing is the conclusion which has the simple things conclude by the researcher from several readings to the novel
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... Show Moreعرفت النظم القانونية انواعا مختلفة من الشركات اذ تعتبر الشركة الوعاء القانوني الاكثر ملائمة لغرض توظيف اموال المستثمرين في مشاريع ذات اهمية والذي يحقق نفا لاصحاب رؤوس الاموال المستثمرة فضلا عن اثرها البالغ على اقتصاد الدول وقد كان للشركة القابضة نصيب من هذا الاهتمام منذ القدم لدى العديد من الدول ووضعت لها احكاما تفصيلية تتناسب مع الاهمية التي يحظى بها هذا النوع من الشركات كونها تجمع لعدة شركات فرعية تسيطر ع
... Show Moreسوسيولوجية "ثوارت" "الربيع العربي (دراسة تحليلية لفعل الثورات العربية)
The Arab woman expressed the life of oppression that she suffers from in her masculine environment, as she expressed her linguistic abilities with eloquence and intelligence, as she did not neglect philosophy, wisdom,
The phenomenon of substitution is one of the morphological phenomena mentioned in the Qur'an, where the researcher defined this phenomenon from the morphological and linguistic points of view and mentioned examples of it by citing references and sources