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Article
Study of hardness and thermal conductivity of polymeric blend reinforced with Kevlar fibers

Authors: Khamees Dhari Mahmoud --- Faiq Hammad Anter
Journal: Diyala Journal For Pure Science مجلة ديالى للعلوم الصرفة ISSN: 83732222 25189255 Year: 2018 Volume: 14 Issue: 02 Pages: 61-75
Publisher: Diyala University جامعة ديالى

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Abstract

This work includes preparation of composite material by reinforcing blend of (EP80% + UPE20%) with different layers of Kevlar fibers (2, 4, 6 and 8) at volume fraction of 30%. Hardness and thermal conductivity of all samples were studied before and after (UV) irradiation. The Experimental results showed that, the hardness value increases with increasing the number of Kevlar layers for all samples before and after (UV) irradiation. The thermal conductivity slowly increases with increasing Kevlar layers before and after (UV) irradiation.


Article
The study of the bending property of the epoxy (Ep / MgO) and (Ep/SiO2) composites in natural conditions and after immersion in chemical solution
دراسة خاصية الانحناء لمتراكب (Ep /MgO) و(Ep/SiO2) في الظروف الطبيعية وبعد الغمر في المحاليل الكيميائية

Authors: Baraa Khalil Ibrahim براء خليل إبراهيم --- Faik Hammad Antar فائق حماد عنتر
Journal: Iraqi Journal of Physics المجلة العراقية للفيزياء ISSN: 20704003 Year: 2018 Volume: 16 Issue: 39 Pages: 93-102
Publisher: Baghdad University جامعة بغداد

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Abstract

In this paper, a polymer-based composite material was prepared by hand Lay-up method consisting of epoxy resin as a base material reinforced by magnesium oxide powder once and silicon dioxide powder again and with different weight ratios (3, 6, 9 and 12) wt %. The three-point bending test was performed in normal conditions and after immersion in sulfuric acid. The results showed that the bending value decreased with the increase of the weighted ratio of the reinforcement material (MgO, SiO2). The Bending of samples reinforced by SiO2 was found to be less than the bending of samples reinforced by particles (MgO). For example, the bending of the SiO2 sample (0.32 mm) at the weighted ratio (3%) and for the MgO (0.18mm) sample at the weight ratio were the same weighted load (100 g). It was found that the bending values of all samples exceeded the value after immersion in sulfuric acid. For example, the percentage of weight (6%) at the load level (500 g) was changed from 1.16 mm in normal conditions to 1.48mm for the same weight ratio after immersion. In sulfuric acid diluted with 0.3N for 10 days at the same applied load.

في هذا البحث تم تحضير مادة متراكبة ذات اساس بوليمري بطريقة القولبة اليدوية مكونة من راتنج الايبوكسي كمادة اساس مدعم بمسحوق اوكسيد المغنيسيوم مرة ومسحوق ثاني اوكسيد السليكون مرة اخرى وبنسب وزنية مختلفة 12, 9, 6, 3) %Wt). وتم اجراء اختبار الانحناء ثلاثي النقط في الظروف الطبيعية وبعد الغمر في حامض الكبريتيك. بينت النتائج ان قيمة الانحناء تقل مع زيادة النسب الوزنية لمادة التدعيم (MgO,SiO2). وجد ان الانحراف للعينات المدعمة بدقائق (SiO2) اقل من الانحراف للعينات المدعمة بدقائق (MgO) فمثلا كان الانحراف لعينة SiO2 (0.32 mm) عند الكسر الوزني (3%) و لعينة MgO (0.18mm) عند الكسر الوزني ذاتة عند مقدار الحمل المسلط ذاته (100 g). وتبين ان قيم الانحراف لجميع العينات قد زادت عن قيمتها بعد الغمر في حامض الكبريتيك فمثلا تغيرت عند النسبة المئوية الوزنية (6 %) عند مقدار الحمل (500 g) من (1.16 mm) في الظروف الطبيعية واصبحت (1.48 mm) للنسبة الوزنية ذاتها بعد الغمر بحامض الكبريتيك المخفف بعيارية 0.3 N لمدة 10ايام عند مقدار الحمل المسلط ذاته.

Keywords

MgO --- SiO2 --- Ep. --- bending property --- H2SO4 --- normal condition.


Article
Erosion Wear and Hardness of Glass Fiber / Epoxy with Nano and Micro TiO2 Hybride Composites

Authors: Amine Achour --- Shatha Riyad Ahmed --- Ahmed A. Al-Tabbakh --- Aseel Basim Al-Zubaidi
Journal: Al-Nahrain Journal of Science مجلة النهرين للعلوم ISSN: (print)26635453,(online)26635461 Year: 2018 Volume: 00 Issue: 1 Pages: 43-51
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

The objective of this research is to prepare and study (Glass Fiber / Epoxy) with nano and micro Titanium dioxide (TiO2) composites with different volume percentage of nano and micro TiO2 powder of 2%, 4%, and 6% volume fraction. Atomic force microscopy techniques was used to measure the grain size of nano TiO2 powder (average diameter was 46 nm) and particle size analyzer techniques was used. Erosive wear behavior of this composite under three different impingement angles of 30°, 60° and 90° and three angular silica sand abrasive particle sizes approximately 425, 600 and 850 μm and hardness (shore D) were studied. In general the erosion wear of micro composites have lower erosion resistance than other nano-based compounds. Erosion resistance increase as the volume fraction increase. Nano composites of GF / EP with TiO2 have many advantages over micro composites from the view point of wear and hardness tests. The worn surface features of unfilled and filled G-E composites were examined using scanning electron microscopy (SEM) and results indicates more severe damage to matrix and glass fiber in unfilled composite system as compared to TiO2 filled composites.


Article
Improving Extractive Multi-Document Text Summarization Through Multi-Objective Optimization

Authors: Nasreen J. Kadhim --- Hilal H. Saleh --- Bara’a Attea
Journal: Iraqi Journal of Science المجلة العراقية للعلوم ISSN: 00672904/23121637 Year: 2018 Volume: 59 Issue: 4B Pages: 2135-2149
Publisher: Baghdad University جامعة بغداد

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Abstract

Multi-document summarization is an optimization problem demanding optimization of more than one objective function simultaneously. The proposed work regards balancing of the two significant objectives: content coverage and diversity when generating summaries from a collection of text documents. Any automatic text summarization system has the challenge of producing high quality summary. Despite the existing efforts on designing and evaluating the performance of many text summarization techniques, their formulations lack the introduction of any model that can give an explicit representation of – coverage and diversity – the two contradictory semantics of any summary. In this work, the design of generic text summarization model based on sentence extraction is redirected into more semantic measure reflecting individually both content coverage and content diversity as two explicit optimization models. The problem is defined by projecting the first criterion, i.e. content coverage in the light of text similarity. The proposed model hypothesizes a possible decomposition of text similarity into three different levels of optimization formula. First, aspire to global optimization, the candidate summary should cover the summary of the document collection. Then, to attain, less global optimization, the sentences of the candidate summary should cover the summary of the document collection. The third level of optimization is content with local optimization, where the difference between the magnitude of terms covered by the candidate summary and those of the document collection should be small. This coverage model is coupled with a proposed diversity model and defined as a Multi-Objective Optimization (MOO) problem. Moreover, heuristic perturbation and heuristic local repair operators have been proposed and injected into the adopted evolutionary algorithm to harness its strength. Assessment of the proposed model has been performed using document sets supplied by Document Understanding Conference 2002 (DUC2002) and a comparison has been made with other state-of-the-art methods. Metric used to measure performance of the proposed work is Recall-Oriented Understudy for Gisting Evaluation (ROUGE) toolkit. Results obtained support strong proof for the effectiveness and the significant performance awarded to the proposed MOO model over other state-of-the-art models.

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