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.
Ottoman Empire created in the state of Algeria staff who manage its affairs on behalf of the Ottomans, who identified their functions and was mostly soldiers Alancksharien, but these soon engaged in Algerian society and coexist with him, and became them their own interests and participated people there in their business and their trades until it became their property and provinces and the interests they manage to order provide for a living.
The calamities, calamities, problems and constant dilemmas that society is experiencing have made it the responsibility of professors and researchers to find appropriate and effective solutions to these issues, and among those calamities that our societies faced was the problem of the epidemic represented by (Corona-Covid-19)
ان ترجمة الافعال التي تصف احداث جارية وقت لحظة التكلم او في حالة استمرارية تفصح عن اختلافًا جذريا بين الإسبانية والعربية بسبب طبيعة الأفعال التي تصف هذه الأحداث، منها تعقيد بعض الصيغ، خاصة باللغة العربية، وعدم التكافؤ النحوي بين اللغتين في الكثير من البنى اللغوية. بهذا المعنى ، نجد أنه في اللغة العربية ، تتم صياغة هذه الظواهر اللغوية عن طريق أفعال تسمى الأفعال الناقصة التي تختلف طبيعتها ووظيفتها داخل الجملة
... Show MoreBaalbek ( Heliopolis- the City of the Sun), one of the most important historical cities in Lebanon, has known as multiple civilizations in successive historical periods, which have left many archaeological evidences, the most important ones are the castle and the roman temples.
The Islamic architectural and artistic heritage in Baalbek was consisted from different types of buildings: religious, civil, military and social in addition to many archaeological arts that were mastered by the Muslims.
عرص كتاب البرلمان في العراق (دراسة للواقع .. وتأملات في المستقبل)
(1)
This search aimed to show a series of converses that our prophet [peace be upon him] call ,some of them , (Kufraa) , and explain the meaning of (AI-kufr) that called on some works , so does it mean the apparent part or the pronunciation of(Al-Kufr) has another meanings ?
تناول هذا البحث مراجعة لعدد من الكتب التي ألفت في جغرافية العراق العربية منها والإنكليزية، وتحديداً الكتب في العصر الحديث، إذ توصل البحث الى وجود مجموعة من الكتب التي تناولت مختلف جوانب العراق الطبيعية منها والبشرية، اتضح أن بعض الكتب الجغرافية تناولت الجانب الجغرافي الطبيعي فقط، في حين أن كتب أخرى تناولت الجانب الجغرافي البشري فقط. وأخرى جمعت بين الجغرافية الطبيعية والبشرية للعراق.
The research seeks to determine the nature of audit services, their characteristics and the basic concepts of services marketing audit and definition of the rules and basic dimensions of the marketing audit services through the knowledge of the elements of the marketing mix and test the preferences of customers and auditors of the factors affecting the marketing audit services by selecting a sample of the owners of some of the projects and companies and a sample of auditors has been use the resolution to achieve the objectives of the research where a good question to the owners about the most important factors in your choice of the Audit Office and asked the organization to answer according to the standard trio (very important, a few imp
... Show MoreThis research has been written as a fullfillment of the researchers
desire of joining the qurannic convoy servos each one from his own place and
this own field of specialization . she has found that the holly quraan is a
parctical field for theories and rules of old and modren phonetic studies also
she has becom a ware of the fact that the quraanic Important –making has
various aspects that neither can be a ware of nor can be vanished by the
courses of ages for science can flourish and reach tops to the extent they
don’t accept any new addition theories can be studied and given laws at last
except the quannice important – making which is new and discovered at
deferent times and places in spite of the shor