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.
Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world’s rivers, representing the environmental influence of 471.4 million people across
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The current research aims to identify the possible self of university students and the differences in the level of possible self of students in terms of gender, specialization (scientific-humanitarian), and the interaction between them. In order to achieve the objectives of the current research, the two researchers have prepared a scale of the possible self, based on the theory (Markus and Nurius, 1986). The research tool was applied to a sample of (400) male and female students who were selected through a random stratified method from Al-Mustansiriya University students/morning studies for the academic year (2019-2020). The researcher reached the following results: the research sample has a high level of possible self; there is a differ
... Show MoreThis study aims to reveal the role of one of the artificial intelligence (AI) techniques, “ChatGPT,” in improving the educational process by following it as a teaching method for the subject of automatic analysis for students of the Chemistry Department and the subject of computer security for students of the Computer Science Department, from the fourth stage at the College of Education for Pure Science (Ibn Al-Haitham), and its impact on their computational thinking to have a good educational environment. The experimental approach was used, and the research samples were chosen intentionally by the research community. Research tools were prepared, which included a scale for CT that included 12 items and the achievement test in b
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There is no doubt that the narrative form is a mixture of many elements that it
becomes so hard to differentiate between them. Thus, to differentiate between those
elements we must understand the job of every element; and that is the structure of narrative
form in the artistic frame of the old Arabic poem.
Poetry, as the readers confirm, is strongly related to a lot of arts. The rhetorical
form is related to the art of drawing and photography, the rhythm- the core of poetry- is
related to music, its structure to the art of architecture, its tension to drama as it consist of
internal conflict between its elements and ingredients, and the poetry has a narrative
element which relates it to the art of narration and it
The current research seeks to shed light on the role that social media can play, through the optimal use of it by students, in achieving academic excellence. The most prominent aims that constitute it are:Identifying the social sites most used by students; learning how students interact with the published study material on communication sites and benefit from them to achieve their academic excellence; and knowing the connection between using social media and achieving academic excellence, and the role that these sites play in achieving academic excellence.That incorrect use by students leads to adverse results, and thus affects their academic level. Failure of parents to monitor their student’ use of social media leads
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התמצית השניות היא התורה שנזכרת כי המוצאים בלשון הערבית וכך בלשונות השמיות אינם הבטויים בעלי האותיות השלושיות , אלא בעלי שתי אותיות . לפי כך אפשר להשיב השורשים השלושיים לשורשים השניים . וכל אות שנאספה בשורש שׁניוני, יהיה לפי חוק ההתפתחות הלשונית , הוספות תחילית , תוכית , סופית , עם השארת החיבור המשמעתית בין השׁניוני והשׁלשׁי כמו היא ממושכת בין השׁלשׁי והרביעי ומה שרבה ההוספות . השרשים השניים מוצאים הם: אות וה
... Show Moreنشأ الانسان منذ بدأ الخليقة محباً للجمال بما يراه من حوله في الطبيعة وكان حريصاً على تزيين نفسه ومنزله بجلود الحيوانات أذ كان السجاد في مراحله الأولى بدائية حتى بلغت الذورة عندما أكتسى السجاد خملة زادته فائدة بأن جعلته أكثر مقاومة وأكثر حفظاً للدفء (الجبوري،2001 ، ص10)وأن التطور الهائل في العلم في هذه السنوات أدى الى أستخدام الكثير من المنتجات والوسائل التي سهلت على الأنسان الكثير من أمور حياته (العبود،2008،ص12) “
... Show Moreالمنطق منهجا نقديا - دراسة في قراءة الشكل الجمالي كتاب (المنطق منهجا نقدياً – دراسة في قراءة الشكل الفني) يهتم الكتاب بدراسة التصورات المنطقية في الفنون التشكيلية وهو يقع في اربعة فصول خصص الاول منها لبيان المنهجية والفكرة العامة عن علاقة المعرفة بالقواعد الفكرية والقواعد المنطقية موضحا ذلك في (مدخل عام) وتعلق الفصل الثاني بالمفاهيم المنطقية وما كتبه علماء المنطق في عرض شامل ومكثف تناول فيه المؤلف مفهوم ال
... Show MoreThis research discussed the freedom of Iraqi women in the thought of Dr. Nazeeha Al-Dulaimi.
أسلوب العطف: دراسة مقارنة بين اللغة العربية والاسبانية