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.
The effect of annealing on the structural and optical properties of Antimony trisulfide (Sb2S3) is investigated. Sb2S3 powder is vaporized on clean glass substrates at room temperature under high vacuum pressure to form thin films. The structural research was done with the aid of X-ray diffraction (XRD) and atomic force microscopy (AFM). The amorphous to the polycrystalline transformation of these thin films was shown by X-ray diffraction analysis after thermal annealing. These films' morphology is explained. The absorption coefficient and optical energy gap of the investigated films are calculated using transmission spectra. Both samples have strong absorption in the visible spectrum, according to UV-visible absorption spectra. The optical
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The research deals with the Presidents of the Christians who called themselves (Ghaltka) in the book titled (orient chirsy patriarchs) that talked about their scientific practical biography adding to) that their completeness on the position of Ghaltka with its decrees and caliphs who were contemporaries to them ,as well as their places, deaths, cemeteries and their accomplishments In accordance with the powers granted to them and also it mentions the situation of The Abbasid caliphate with them and with the sons of their sect .
he is one of the most prominent Arab personalities who contributed in the Arab Muslim world, scholars and historians who appeared in the seventh century AH - the thirteenth century AD, contributed to enrich the Arab scientific heritage in his distinguished book “The Wonders of Creatures and the Strangeness of Existences” because it contained what God Almighty created and the oddities on dry land and water
Urinary stones are one of the most common painful disorders of the urinary system. Four new technologies have transformed the treatment of urinary stones: Electrohydraulic lithotripsy, ultrasonic lithotripsy, extracorporeal shock wave lithotripsy, and laser lithotripsy.The purpose of this study is to determine whether pulsed holmium laser energy is an effective method for fragmenting urinary tract stones in vitro, and to determine whether stone composition affects the efficacy of holmium laser lithotripsy. Human urinary stones of known composition with different sizes, shapes and colors were used for this study. The weight and the size of each stone were measured. The surgical laser system which used in our study is Ho:YAG laser(2100nm)
... Show Moreبحثنا الموسوم بـ (الأغلاط اللغوية في كتاب الإنسان الثاني لمحمود عباس العقاد دراسة في ضوء كتب التصحيح اللغوي الحديثة)، ليس الغاية منه النيل من شخص كاتب كبير، وعلم من أعلام الأدب العربي، بل اعتماد الموضوعية والرد على القول الشائع: (الخطأ الشائع خير من الصواب الضائع)، إذ إِن كثيرًا ممن يسلكون درب الأغلاط اللغوية يعمدون الى التمسك بها محتجين بأن ما ورد في تعبيراتهم ورد في تعبيرات كتّاب كبار، فضلاً عن أن الباحثة ل
... Show MoreThe writer of this messagewas Tajaddin Ahmad Abdulqader bin Maktoom Al-Qaisy Al-masry.
This message dealt with the biographies of twenty scientists of readers about Quran readings in Cairo . He comprehended these biographies and make it an appendage
يهدف البحث الى دراسة وتحليل التمويل الأخضر كأحد المفاهيم الاساسية والحديثة في عالم الاعمال والاقتصاد العالمي وخاصة بعد الازمات والتحديات التي توالت على العالم نتيجة الكوارث الطبيعة وتغييرات المناخ والضغوطات على الموارد الطبيعية والتي أدت الى احداث اثرا كبيرا في اقتصاديات الكثير من الدول ، مما اضطرت الى إعادة النظر في مشاريعها وانشطتها الاستثمارية بما يوائم وطبيعة البيئة ومتغيراتها ، لذا تحتم اختيار لمثل
... Show Moreان نجاح رياض الاطفال في تحقيق اهدافها يتوقف الى حد كبير على معلمة الروضة التي تزود الطفل بالخبرات ، فهي تمثل الام البديلة للطفل ، وتقع على عاتقها مسؤوليات نفسية واجتماعية واخلاقية نحو اطفال الروضة ، لدلك فان معلمة الروضة تقوم بعدة ادوار في رياض الاطفال ، فهي ممثلة لقيم المجتمع وتراثه التي تسعى الى غرسها في الطفل .
وعليه فان ليس كل من تتقدم للعمل في رياض الاطفال تصلح ان تكون معلمة ناجح
... Show MoreTax justice is one of the important principles that any tax system seeks to achieve because it is an important and important pillar of the tax because it has negative repercussions on the tax accounting process on the one hand and the low tax revenues on the other hand. Therefore, countries have sought through their tax systems to use methods and methods In the process of estimating taxable incomes to achieve that justice depending on the awareness of their communities. The method adopted differs from one country to another according to the knowledge and understanding of the society of that state for taxation and its role in economic, social and political life. In Iraq, the General Authority for Taxation Methods of estimating taxable inc
... Show MoreThis research aims to improve the process Tax accounting by using the scientific method to such as Six Sigma DMAIC steps called in General. Authority for Tax accounting . this approach has been described Tax accounting process Fully and identify problems experienced by the measurement and analysis and identify the critical success factors to satisfy customers and adoption process redesign Tax accounting process with the possibility of obtaining a high-quality revenue to be used by the body to improve its performance . Collected data and information from interviews with officials, staff and see the details & the conduct & operations in the body, and used well as a questionnair to measure the quality & services present action b
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