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Comparisons of Mechanical Properties of sub-mm Lead Based and Lead Free Based Solder Using in Manufacturing of Printed Circuits
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Abstract

This study investigates the mechanical compression properties of tin-lead and lead-free alloy spherical balls, using more than 500 samples to identify statistical variability in the properties in each alloy. Isothermal aging was done to study and compare the aging effect on the microstructure and properties.

The results showed significant elastic and plastic anisotropy of tin phase in lead-free tin based solder and that was compared with simulation using a Crystal Plasticity Finite Element (CPEF) method that has the anisotropy of Sn installed. The results and experiments were in good agreement, indicating the range of values expected with anisotropic properties.

Keywords: Lead-free solder, composite solder, and aging.

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Publication Date
Tue Mar 30 2021
Journal Name
Baghdad Science Journal
Variant Domination Types for a Complete h-ary Tree
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Graph  is a tool that can be used to simplify and solve network problems. Domination is a typical network problem that graph theory is well suited for. A subset of nodes in any network is called dominating if every node is contained in this subset, or is connected to a node in it via an edge. Because of the importance of domination in different areas, variant types of domination have been introduced according to the purpose they are used for. In this paper, two domination parameters the first is the restrained and the second is secure domination have been chosn. The secure domination, and some types of restrained domination in one type of trees is called complete ary tree  are determined.

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Publication Date
Thu Jul 01 2010
Journal Name
Political Sciences Journal
حل الاشكالية المنهجية في العلوم الانسانية المنهج البنيوي انموذجاً مقترحاً
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حل الاشكالية المنهجية في العلوم الانسانية المنهج البنيوي انموذجاً مقترحاً

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Publication Date
Mon Nov 02 2020
Journal Name
جامعة بغداد/ كلية التربية للعلوم الصرفة - ابن الهيثم
مستويات الفهم الرياضـي المتضمنة في كتاب الرياضيات للصف الثاني المتوسط
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Publication Date
Fri Aug 31 2018
Journal Name
مجلة العلوم النغسية
أثر استراتيجية تعليمية في تحصيل مادة العلوم لطلاب الاول المتوسط
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ن الهدف من هذا البحث هو معرفة أثر إستراتيجية تعليمية في تحصيل مادة العلوم لدى طلاب الصف الاول المتوسط. ولتحقيق هدف البحث صاغ الباحثان الفرضية الآتية: لا توجد فروق ذو دلالة إحصائية عند مستوى (0,05) بين متوسط درجات طلاب المجموعة التجريبية الذين يدرسون مادة العلوم وفق إستراتيجية تعليمية وبين متوسط درجات طلاب المجموعة الضابطة الذين يدرسون المادة نفسها بالطريقة التقليدية في اختبار التحصيل. بلغت عينة البحث (59) طالبا

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Publication Date
Fri Feb 08 2019
Journal Name
Journal Of The College Of Education For Women
العوامل المؤثرة في تخفیف الأعباء المنزلیة لدى المرأة العراقیة العاملة
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In the past, an absolute authority was held by the father and his decisions were imposed
and obeyed strictly without discussion. Later, many economical changes took place and
affected all of the family members dramatically creating a whole new concept of authority
in the family, a one that is based upon sound leadership, mutual understanding and
consultation among family members.
Women carried responsibility of doing all domestic jobs and served family members,
however, when she went to work outside her house, these loads began disturbing and
exhausting her. Therefore, man started to participate in assisting his wife. In addition,
industrial advances contributed in making these jobs easier than before.
This has

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Publication Date
Thu Feb 01 2018
Journal Name
Journal Of Economics And Administrative Sciences
The role Government Securities Market on the Iraqi Credit worthiness
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تشكل  التغيرات الحاصلة في اسعار النفط تحديا" حقيقيا" لاستمرار عملية النمو في العراق, وامام الحكومة فرصة كبيرة لإيجاد حلول ناجعة لمشكلة تزايد عجز الموازنة العامة من خلال اللجوء الى اصدار ادوات الدين العام الداخلي والخارجي, وهذا يتطلب بناء استراتيجية لإقامة وتطوير سوق السندات الحكومية في العراق, لتتمكن الحكومة من خلاله توفير مصادر تمويل اضافية, تسهم في تمويل الانفاق الاستثماري الحكومي ودعم النمو ودعم

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Publication Date
Sun Oct 01 2017
Journal Name
Journal Of Educational And Psychological Researches
أثر انموذج دانيال في الدافعية المعرفية لطلاب الصف الثالث المتوسط
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The Current research aims to identify ( The effects of Daniel Model in Cognitive Motivation for the Students of the Third grade average ) , To verify the objective of this research , the researchers added nul hypothesis following : There is no difference is statistically significant at the level of ( 0.05 ) between the average scores of students who studied Daniel Model and the average students who studied by using traditional method in Cognitive Motivation scale. The research was conducted on a sample of the average Third grade students in a medium Al – sadiq Al – Ameen secretary for boys affiliated to the General Directorate for Educational in Baghdad Al – rusafa 2 and for academic year ( 2014 – 2015 ) , the researchers adopted

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Publication Date
Mon Dec 01 2008
Journal Name
Journal Of Economics And Administrative Sciences
السياسة النقدية في العراق بعد 9/4/2003 (الواقع والطموح)
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لا يستطيع كل كائن حي أو كيان اجتماعي أداء دوره الذي يفترض أن يقوم به ما لم يمتلك الوسائل الكافية والضرورية لأداء ذلك الدور قال سبحانه وتعالى ((قال ربنا الذي أعطى كل شيء خلقه ثم هدى طه 50)).

والنشاط الاقتصادي كجزء من الكيان الكلي للمجتمع لا يختلف عن هذه القاعدة، إذ عندما يراد من النظام الاقتصادي أداء دور فاعل فلا غنى له عن الوسائل التي تمكنه من أداء دوره المنشود. للنظام الاقتصادي مجمو

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Publication Date
Wed Jun 07 2023
Journal Name
Journal Of Educational And Psychological Researches
Omani Second-Cycle Students’ Motivations for Electronic Games
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The current study aims to investigate the second cycle students’ motives for using electronic games in Oman. The sample consisted of (570) students, (346 males and 224 females). The participants completed an open-ended question which was analyzed based on ground theory. The results showed that (46.820%) of the males and (77.678) of the females played electronic games for pleasure, entertainment, and fun. This first category of motivation got the highest percentage of frequency (58.947%). The motive to become a hacker, a popular YouTuber got the lowest percentage (2.280%). Other students’ motives toward playing electronic games included: filling the leisure time, overcoming boredom, feeling adventures, getting science fiction and chal

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Publication Date
Thu Dec 01 2016
Journal Name
Journal Of Economics And Administrative Sciences
Use the le'vy Model on stock returns for some Iraqi banks estimate
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In this article we  study a single stochastic process model for the evaluate the assets pricing and stock.,On of the models le'vy . depending on the so –called Brownian subordinate as it has been depending on the so-called Normal Inverse Gaussian (NIG). this article aims as the estimate that the parameters of his model using my way (MME,MLE) and then employ those  estimate of the parameters is the study of stock returns and evaluate asset pricing for both the united Bank and Bank of North which their data were taken from the Iraq stock Exchange.

which showed the results to a preference MLE on MME based on the standard of comparison the average square e

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