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alkej-347
Experimental and Numerical Research on Flow-Induced Vibration in Valves
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Abstract  

All central air conditioning systems contain piping system with various components, sizes, material, and layouts. If such systems in operating mode, the flow in piping system and its component such as valves can produce severe vibration due to some flow phenomenon’s. In this research, experimental measurements and numerical simulation are used to study the flow-induced vibration in valves. Computational fluid dynamics (CFD) concepts are included with one-way and two-way fluid-structure interaction concepts by using finite element software Package (ANSYS 14.57). Detection analysis is performed on flow characteristics under operation conditions and relations with structural vibration. Most of real geometrical, operational, and boundary conditions are simulated to obtain best similarity with real operation conditions. Comparisons performed between experimental data and numerical results (one-way and two-way simulation) to verify the results. The main conclusion was drawn from the study that the dominant source of vibration for valve is the water pulsation in addition to amount of water hammering. In addition, the main source of water pulsation in globe valve is the vortex shedding and pressure difference between upstream and downstream of valve. The vibration amplitude was increased with increasing flow rate until to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and then trends to be constant.

Keywords: Flow-induced vibration, vortex shedding, pressure pulsation, valve, finite element, ANSYS, fast Fourier transform (FFT).

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Publication Date
Thu Jan 02 2020
Journal Name
Journal Of The College Of Languages (jcl)
Some of the Grammatical Rules of Writing: Zu einigen grammatischen Erscheinungen im Schreiben
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    Language contains various kinds of grammatical rules that are used to express thoughts and feelings. The present paper studies some of the German language grammatical rules as being the most important basics needed to master and develop the art of writing for the German language learners. Writing is one of the productive language learning skills that transform thoughts into a written form. Hence, constant exercising on the use of the language to master the grammatical rules enables German language learners to develop their creative writing skills.

     The present study discusses the importance of grammatical exercises in developing the language learning abilities. The study provides a gener

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Publication Date
Fri Apr 01 2022
Journal Name
Baghdad Science Journal
Improved Firefly Algorithm with Variable Neighborhood Search for Data Clustering
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Among the metaheuristic algorithms, population-based algorithms are an explorative search algorithm superior to the local search algorithm in terms of exploring the search space to find globally optimal solutions. However, the primary downside of such algorithms is their low exploitative capability, which prevents the expansion of the search space neighborhood for more optimal solutions. The firefly algorithm (FA) is a population-based algorithm that has been widely used in clustering problems. However, FA is limited in terms of its premature convergence when no neighborhood search strategies are employed to improve the quality of clustering solutions in the neighborhood region and exploring the global regions in the search space. On the

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Publication Date
Sun Jan 03 2010
Journal Name
Journal Of Educational And Psychological Researches
اثر الاسئلة السابرة في تحصيل طلاب الصف الرابع العام لمادة التاريخ
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The importance of teaching methods and procedures comes from the nature and significance of the questions raised inside the classroom. That is, because questions, in fact, are the means of communication and interaction in the class situation. Therefore they are considered as indispensible elements in any teaching approach. Furthermore, it is noticeable that the majority of teachers fail in using them, for questions are often casted spontaneously and without pre-planning. Hence, a delay may occur in realizing the pre-set objectives, and let alone the dominance of stereotyped questions, especially when the teachers focus on a type of question which can be directly answered from the text-book.

      &nb

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Publication Date
Sun Apr 01 2012
Journal Name
Journal Of Educational And Psychological Researches
تطوير واقع مقرر التطبيقات التدريسية في أقسام كليات التربية جامعة بغداد
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The followers of the reality of the decision application faculty in departments of faculties of education of the University of Baghdad, it is noted that there are many shortcomings, which relate to Path, management, design, and evaluation, Coming from the work of the researcher as a teacher and supervisor, as well as to inform the researcher on many of the studies and literature, luck researcher on the article there are no courses are clear in theory and in practice the decision of the applications teaching, and often puts the teacher education curriculum, which lacks the link between the theoretical and practical, either in relation to its management, there is no office for the management and coordination at the University of Baghdad or

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Publication Date
Thu Apr 07 2022
Journal Name
Journal Of The College Of Basic Education
تاثير تمرينات خاصة في السرعة الادراكية وتعلم بعض المهارات الارضية بالجمناستك
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Publication Date
Tue Oct 05 2021
Journal Name
Arab Science Heritage Journal
مصنفات المؤرخ الاستاذ الدكتور عبد الله الفياض في تاريخ الحضارة الإسلامية
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The historian, Professor Dr. Abdullah Al-Fayyad, left a huge legacy of knowledge product that scholars and stakeholders benefited from in the field of Islamic historical and modern studies,

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Publication Date
Tue Apr 01 2008
Journal Name
Journal Of Educational And Psychological Researches
التربية النفسية والاخلاقية عند مسكويه في كتابه ( تهذيب الاخلاق وتطهير الاعراق)
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أن الامم والشعوب لاتستطيع المحافظة على استمرار وجودها وتقدمها ورقيها، إلابفضل إعداد اجيالها المتعاقبة الاعداد السليم المتكامل ، وبقدر ما تحافظ الامم والشعوب على تربية هذه الاجيال للتمسك بدينها ، ومعتقداتها ، واخلاقها ، بقدر ما تحافظ على بقائها وعلو شأنها ، وكما فطنت الامم والشعوب إلى اهمية تربية اجيالها ، فطن اعداؤها الى ضرورة التخريب في جذور البناء الصحيح لتربية الاجيال ( فاطمة ، 1998، ص2).

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Publication Date
Fri Jan 01 2021
Journal Name
مجلة جامعة الامام جعفر الصادق(ع ) للدراسات القانونية
حق العمل والتوظيف لذوي الاعاقة في ضوء الاتفاقيات الدولية والتشريعات العراقية
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يُعدّ الأشخاص ذوو الإعاقة أكبر أقلية في العالم وأكثرها حرمانًا، حيث تشير الإحصاءات إلى أن نحو مليار شخص، أي ما يعادل 15% من سكان العالم، يعانون من بعض أشكال الإعاقة، مع تزايد معدلاتها في البلدان النامية. وتشير الدراسات العلمية إلى أن ذوي الإعاقة قادرون على مزاولة العمل بإتقان ومثابرة، بل وقد تتفوق مهاراتهم أحيانًا على مهارات الأشخاص غير المعاقين، إذا تم اختيار العمل المناسب لقدراتهم ومواهبهم. كما أن حق العمل

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Publication Date
Wed Mar 22 2023
Journal Name
مجلة الجامعة العراقي ة
اتجاهات معاصرة في ط ا رئق التدريس التعلم النشط أنموذج ا
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يعد التعلم النشطعملية نشطة ذهنية يبذٌل بها العقل الجهد الكافي لإِكتشاف المعرفة فالمعلمليس ناقلاً فيه للمعرفة ،) وانما مرشداً وموجهاً والمتعلم محور العملية التدريسية فيه،إِي عمليةإِبداع يختار منها المعلمما يستطيع الابداع فيه وتركيبه)حارص، 2015:6 والتعلم النشط طريقة تعاونية يشترك فيها جميع المتعلمين بالأنشطة والواجبات المتنوعة التي تسمح لهم بالأصغاء الإِيجابي والتحليل السليم للمادة والتفكي ا رلابداعي اذ تت

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Publication Date
Thu Sep 01 2022
Journal Name
العلوم النفسية
( التفكك الاسري لدى تلامذة الصف السادس الابتدائي في ضوء بعض المتغيرات)
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الملخص: لتحقيق أهداف البحث قامت الباحثتان ببناء مقياس للتفكك الاسري اعتمادا على نظرية (باندورا) وتكون بصورته النهائية من (24) فقرة ، وطبق المقياس على عينة البحث البالغة (150) تلميذ وتلميذة تم اختيارهم بالطريقة العشوائية البسيطة من مجتمع البحث ،وبعد جمع البيانات تم معالجتها باستعمال الوسائل الإحصائية منها الاختبار التائي، وتحليل التباين الرباعي والاختبار الفائي، وتوصل البحث الى النتائج الأتية :ان أفراد عينة ال

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