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.
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 Moreعرف العرب ، منذ القدم ، الأحجار الكريمة وعنوا بإقتناء أنواعا عديدة منها ، حيث كانت من أهم واردات سكان بلاد وادي الرافدين من السومريين والبابليين ثم الآشوريين ، كما عرفها المصريون القدماء وغيرهم من الشعوب القديمة ، فوجدت في قبورهم ومدافنهم وخزائن كنوزهم، مثل الياقوت الأحمر واللازورد واللؤلؤ . بالإضافة إلى ذلك فقد كان معدني الذهب والفضة من المعادن الوفيرة في هذه البلاد ، ولها الأولوية في صناعة الحلي.
The collapse of Al-Khwarizmi state is due to special factors relating to Al-Khwarizmi state, and general factors submit to the standards of fighting, and of the Islamic countries and the inability of the Islamic world to confront all the challenges it faced, especially the Mongols and frequent glamour and and conflict on the governance: (who receive the leadership, and who kills of, and who fights of) all these conditions led
Praise be to God, Lord of the worlds, and may blessings and peace be upon the most honorable of all creation, Abi Al-Qasim Muhammad, and the God of the good and pure
اصبح مصطلح الصورة الذهنية من المصطلحات الشائعة التي يتزايد استخدامها في المجالات السياسية والإعلامية والعلاقات الدولية اذ اصبح يشكل اهمية كبرى لدى دراسي السلوك الانساني، فقد احتلت دراسة المصادر المتعددة التي يستقي منها الافراد انطباعاتهم عن الاخرين، وتعاظم الدور الذي تلعبه وسائل الاتصال في تدفق الصور عن الشعوب في ظل التطور التكنولوجي الهائل الذي يشهده عالم الاتصال حاليا، والذي يسمى بعصر السموات المفتوحة
... Show MoreAndalucía, dentro del mapa lingüístico español, es una región con muchas variaciones dialécticas. En muchos casos contiene una gran variedad de términos propios de la zona, ya que en esta misma zona se pueden observar muchas subdivisiones dialectales.
En este trabajo, hemos seguido dos tipos de fuentes:
- Directa: Se trata de conseguir la información por medio de cuestionarios distribuidos a informantes de edades y localidades diferentes.
- Indirecta: Consultando libros para conseguir información y datos básicos del tema, e información sobre las voces y nombres dialectales en la geografía estudiada.
This 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
This Research on (Ayat of Advice and Guidance of Morals
Included in Sorat Al-Baqara) is a study for the virtual of Ayat
dealing with advice and guidance.
The importance of this research title comes from the study of
the Holy Quran from one side and the importance of advice and
guidance from the other side, besides, we are truly in need for
such study in our life.
This research has targeted four aims related to the social morals of university students in terms of psychological aspect and Islamic field; they had been achieved as follow:
- It had been sought in the social morals concept in Islam in relation to the Holy Quran and Hadith sources.
- It had been built standard for the social morals of the university students through analyzing Hadith and adopting focus ratio to identify the number of ten social moral items; and they have been subjected to the statistical analysis then finding the psychometric indicators to identify their truth and validity.
- To identify the ratios of social morals at a sample of Isla