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Experimental Study on the Effect of Insertion of Copper Lessing Rings in Phase Change Material (PCM) on the Performance of Thermal Energy Storage Unit
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Abstract

One of the most suitable materials to be used in latent heat thermal energy storage system (LHTES) are Phase change materials, but a problem of slow melting and solidification processes made many researchers focusing on how to improve their thermal properties. This experimental work concerned with the enhancing of thermal conductivity of phase change material. The enhancing method was by the addition of copper Lessing rings in phase change material (paraffin wax). The effect of diameter for the used rings was studied by using two different diameters (0.5 cm and 1cm). Also, three volumetric percentages of rings addition (3%, 6% and 10%) were tested for each diameter. The discharging process was done with four velocities for each case. The obtained results indicated that the maximum volumetric percentage gave a diminished time for melting and maximized the heat transfer in both PCM and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. In case of 1 cm rings diameter minimum time for melting was obtained for both 3% and 6% volumetric percentages as compared with the same percentages in case of 0.5 cm diameter rings, while the latter with 10% volumetric percentage overcomes the 1 cm diameter rings for the same previous percentage. Also it can be seen that the minimum velocity (v=1m/s) gave the utmost outlet temperature and with the maximum one (v=3m/s), the minimum solidification time achieved.

Keyword: Thermal energy storage systems, Latent heat storage, Phase change materials, Heat transfer enhancement.

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Publication Date
Sat Dec 01 2007
Journal Name
Journal Of Economics And Administrative Sciences
استهداف السعر كأساس لتحقيق تقنية التكلفة المستهدفة للوحدات الاقتصادية العاملة في بيئة الأعمال الحديثة
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المقدمة

تمثل الأسعار تعبيرا" نقدياً لقيمة السلع والخدمات المقدمة للزبون، وتعد عملية التسعير من العمليات المهمة وذات الأثر البالغ على نجاح واستمرار منظمات الأعمال، نظراً لما لها من تأثير على المقدرة الربحية وإعادة توزيع الدخل القومي المخصص للاستهلاك، إذ أنه بتحديد الأسعار يستطيع الفرد أن يوزع دخله بين ما يعده ضرورياً من السلع وما يعد كمالياً.

وعموماً فإن لعملية التسعير م

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Publication Date
Wed Jul 01 2015
Journal Name
Journal Of Educational And Psychological Researches
مستوى التنمية المهنية لتدريسيي جامعة بغداد في ضوء مؤشرات الجودة الشاملة من وجهة نظرهم
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The present study aimed to know The teaching members’ level of the professional development at the University of Baghdad based on the indicators of the overall quality from their perspective;

The researchers used the descriptive and analytical approach the in order to achieve the purposes of research, the researchers designed questionnaire researched and consisted of 40 paragraph has the questionnaire submitted to the arbitrators and experts were verify the authenticity of the questionnaire and stability have been applied questionnaire on a range of teaching and Tdriciat Baghdad University, which reached the study sample (400) teaching and teaching of six colleges in the University of Baghdad equivalent

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Publication Date
Tue Feb 01 2022
Journal Name
Baghdad Science Journal
Milk Tumor Necrosis Factor Alpha and Interleukin-1Beta Among Toxoplasma gondii-Free and Infected Women
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Pro-inflammatory cytokines play an important role in intercellular communications. In the last two decades, many cytokines have been identified in human milk. These cytokines are variable according to different conditions such as pathogenic infections which strongly stimulated the immune response. The present study aims to determine of IL1β and TNF-α in Toxoplasma gondii-free and infected women in an attempt to clarify the impacts of the infections on cytokines especially in mother's milk. The serum and milk sample were collected from 96 samples (48 for seropositive and 48 for seronegative). To confirm the Toxoplasma gondii infection; enzyme linked immunofluorescence assay (ELIFA) was used to detect anti-Toxoplasma Ig

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Publication Date
Tue Feb 14 2023
Journal Name
Journal Of Educational And Psychological Researches
Vocabulary Learning Strategies Employed by English as Foreign Language Students at NBU University
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ABSTRACT

Learning vocabulary is a challenging task for female English as a foreign language (EFL) students. Thus, improving students’ knowledge of vocabulary is critical if they are to make progress in learning a new language. The current study aimed at exploring the vocabulary learning strategies used by EFL students at Northern Border University (NBU). It also aimed to identify the mechanisms applied by EFL students at NBU University to learn vocabulary. It also aimed at evaluating the approaches adopted by EFL female students at Northern Border University (NBU) to learn a language. The study adopted the descriptive-analytical method. Two research instruments were developed to collect data namely, a survey qu

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Publication Date
Mon Sep 01 2008
Journal Name
Journal Of Economics And Administrative Sciences
مقارنة طرائق تقدير معلمات توزيع كاما ذي المعلمتين في حالة البيانات المفقودة باستخدام المحاكاة
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The estimation of the parameters of Two Parameters Gamma Distribution in case of missing data has been made by using two important methods: the Maximum Likelihood Method and the Shrinkage Method. The former one consists of three methods to solve the MLE non-linear equation by which the estimators of the maximum likelihood can be obtained: Newton-Raphson, Thom and Sinha methods. Thom and Sinha methods are developed by the researcher to be suitable in case of missing data. Furthermore, the Bowman, Shenton and Lam Method, which depends on the Three Parameters Gamma Distribution to get the maximum likelihood estimators, has been developed. A comparison has been made between the methods in the experimental aspect to find the best meth

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Publication Date
Sun Apr 03 2011
Journal Name
Journal Of Educational And Psychological Researches
اثر الانموذج المعملي في تصحيح المفاهيم الرياضية شائعة الخطأ لدى طلاب الصف الاول المتوسط
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ملخص الدراسة
سعت الدراسة تعرف اثراستعمال الأنموذج المعملي في تصحيح المفاهيم الرياضية شائعة الخطأ لدى طلاب الصف الأول المتوسط بالإجابة عن السؤال "ما اثر استعمال الأنموذج المعملي في تصحيح المفاهيم الرياضية شائعة الخطأ لدى طلاب الصف الأول المتوسط" ولتحقيق هدف الدراسة وضعت الفرضية الصفرية "لايوجد فرق ذو دلالة إحصائية عند مستوى الدلالة (0.05) بين متوسطي درجات طلاب المجموعة التجريبية الذين يدرسون المادة المقرر

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Publication Date
Wed Dec 04 2024
Journal Name
المكتب العربي للمعارف
إدراة الصراع بين القوى الإقليمية في آسيا بعد 2011 (الصين والهند وروسيا واليابان )انموذجاً
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تعيش قارة آسيا حالة فريدة تكاد تقترب من حالة أوروبا قبل الحرب العالمية الثانية، فالقارة حاليا تحتوي على العديد من القوى الإقليمية الفاعلة أبرزها الصين وروسيا والهند واليابان، أما القوى الإقليمية الفاعلة في نطاق نظمها الإقليمية الفرعية نجد من أهمها الكوريتين (الشمالية والجنوبية)، وباكستان، وإيران وغيرها، ووجه الاختلاف عن أوروبا هو أن آسيا منطقة شاسعة جغرافياً، وكل نظام إقليمي فرعي فيها هو نظام قاري بحد ذات

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Publication Date
Sun Apr 28 2019
Journal Name
Arab Science Heritage Journal
الظواهر الظواهر الاجتماعية في بغداد من خلال كتاب الظرف والظرفاء لابي الطيب الوشاء(ت320هـ)
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 the study of social phenomena in this direction is, the sign of deviousness to the segments of the circumstance with their conditions and circumstances, then pointed to the uniforms that they were adorned by the tortillas as well as shirt Safaf from good linen soft and touched the country and the good and others.

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Publication Date
Mon Dec 01 2008
Journal Name
Journal Of Economics And Administrative Sciences
قياس وتحليل تفاعل عمل المضاعف والمعجل في الاقتصاد العراقي باستخدام نموذج المستخدم – المنتج الديناميكي
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The individual average income is considered one of the most used criteria for the distinguishing between the developed and the developing countries, for this reason the efforts of economic development has been construed on increasing the average national income, the investment expenditures is considered one of the basic foundations for economic development operation which lead to the expanding the prodection power of the economy, and increasing the level of national income in an averages greaten than the primary expenditures due to the work and interaction between the multiplier and the accelerator. But the ability of the economic sectors in the generation of national income as a result of the primary expenditures is different fr

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Publication Date
Sat Sep 01 2007
Journal Name
Journal Of Economics And Administrative Sciences
صياغة أهداف المحاسبة والتقارير المالية في ظل اختلاف المتغيرات البيئية أفكار مطروحة وأراء مقترحة
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المقدمة ومنهجية البحث

تتفق أغلب الأدبيات ومنها المحاسبية, بأن الخطوة الأولى في وضع وتقييم أي نظام إداري أو محاسبي هي في صياغة أهداف ذلك النظام لما لذلك من أهمية في توفير معيار للحكم على كفاءة التطبيق من عدمه.

وتعرف الأهداف بأنها (النهايات التي تعمل أو توجه النشاطات باتجاهها أو هي النهايات التي تطمح النشاطات تحقيقها). ( 1 ) ..,

 كما تعرف أيضا بأنها (الأ

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