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Article
Numerical and Experimental Investigation of Mechanical and Thermal Buckling Loads of Composite Laminated Plates

Authors: Ammar A. Hussein --- Hassan H. Mahdi --- Nessren H. Ahmed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 9 Pages: 1830-1844
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In this study, the effect of temperature, aspect ratio, number of layer andboundary conditions on critical buckling load of composite laminated plate isinvestigated experimentally and numerically. Simply-Simply-Free-Free andClamp-Clamp-Free-Free boundary conditions, three temperatures (40°C, 60°C and80°C) and four aspect ratio (1, 1.3, 1.5 and 2) will consider for the experimentalwork. The thickness of the plate was changed by increasing the number of layer.It can be seen that when the temperature changes from 40°C to 80°C themaximum value of Pcr is about (225 N/mm) at (T = 40°C, a/b = 2 and NL = 4), theminimum value of Pcr is about (11.70 N/mm) at (T = 80°C, a/b = 1 and NL = 2).Also, it can be shown that in the case of symmetric cross ply laminate (0o/90o/0o)when the thermal load increased by about 100 % the buckling load decrease byabout 50 % at aspect ratio equal to 1. Finally, It is shown that the critical bucklingload increases with increasing the aspect ratio at constant temperature, number oflayers and boundary conditions.


Article
Clinicopathological Findings of IgA Nephropathy in Children and Adolescents; (Multicentn Study)

Author: Alaa M. Neamah*, Ammar A. Hussein** ,Hasanein H. Ghali*** , Qutaiba A. Hussein**
Journal: Iraqi Academic Scientific Journal المجلة العراقية للاختصاصات الطبية ISSN: 16088360 Year: 2016 Volume: 15 Issue: 3 Pages: 338-343
Publisher: The Iraqi Borad for Medical Specialization المجلس العراقي للاختصاصات الطبية

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Abstract

ABSTRACT:BACKGROUND: IgA nephropathy (IgAN) is the most common lesion found to cause primary glomerulonephritis throughout most developed countries of the world. Patients may present at any age, but there is a peak incidence in the second and third decades of life. OBJECTIVE:To study the demographic, clinical and laboratory findings of IgAN patients including children and adolescents.METHODS: The medical records of 30 patients with IgAN were retrospectively reviewed and assessed. Patients enrolled in this study were between 1-18 years old diagnosed as IgAN in the period from January 2010 to the end of December 2012 being treated and followed in the main three centers of treating cases of pediatric nephrology in Baghdad (Al-karama teaching hospital, Central Child Teaching Hospital and Baghdad Medical City) that receive referral cases from all Iraqi governorates. RESULTS: The total number of cases enrolled in this study was 30 patients, with males being 19 and females being 11. The male to female ratio was 1.72:1. Family history of chronic renal disease was found in 10 patients (33%). History of pharyngitis was found in 16 patients (53.3%). Macroscopic hematuria was found in 24 patients (80%), followed by edema in 18 patients (60%), and followed by hypertension in 15 patients (50%). The most common laboratory findings among study group was microscopic hematuria (29 patients, 96.7%), followed by proteinuria in 22 patients (73.3%). Renal biopsy was done for all patients for the diagnosis of IgAN. The distribution of histopathology staging system was: Stage (1) 14 patients, Stage (2) 8 patients, Stage (3) 5 patients, Stage (4) 2 patients and Stage (5) 1 patient (46.7%, 26.7%, 16.7%, 6.7% and 3.3% respectively). The study showed that 24 patients were found to have IgA deposited solely (80%). Out of the total 12 patients presented with hematuria, nine of them (75%) showed stage 1 disease on histopathology study. Two patients were noticed to have other associated autoimmune diseases, one with hepatitis and another with ulcerative colitis. CONCLUSION: Further studies in large number of patients are needed in order to confirm the findings in this study and to establish the best therapeutic choice for IgAN. The need for immunofluorescence examination of the renal biopsies in suspected cases is recommended.


Article
EVALUATION OF WEAR IN DIE MATERIAL FOR WARM FORGING PROCESS
حساب البلى لمادة القالب في عملية التشكيل الدافئ

Authors: Nasri S. Mohammed نصري صالح محمد --- Ammar A. Hussein عمار علي حسين --- Firas J. Abdulraheem فراس جمعة عبد الرحيم
Journal: AL-TAQANI مجلة التقني ISSN: 1818653X Year: 2015 Volume: 28 Issue: 1 Pages: E149-E162
Publisher: Foundation of technical education هيئة التعليم التقني

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Abstract

In this work the methodology to evaluation the abrasive wear in closed warm forging die blocks material were manufactured from hot work tool steel H13 in two conditions; unquenched and quenched and tempered (QT).Two hundred flat countersunk head rivet are produced by warm forging operation, 100 forging (rivet) in each die block material.The wear in die is evaluated by implementing a methodology of measuring the used (worn) dies profile by a coordinate measurement machine CMM, then compensate the predicted plastic deformation die surface by using FEM-simulation code DEFORMTM-2D to separate the captured wear depth in die surface profile. The measured (separated) wear depth is used in Archad’s wear model to estimate the experimental wear coefficient (K) in order to comparing it with the predicted (numerical) wear coefficient (K) from simulation of forging operation. The suggestion of a new wear coefficient (K) to optimizing the forging process, gives the designer a possibility of forecasting the reached wear level.The numerical results showed a good agreement with experimental where the maximum differences are (12 % and 12.6 %) for unquenched and quenched and tempered die material respectively.

في هذا البحث تم دراسة كيفية حساب البلى التآكلي لوحدة القالب (Die Blocks) لقالب الطرق الدافئ المغلق مصنعة من فولاذ العدد المقاوم للحرارة H13 بحالتيه الغير مصلد والمصلد والمراجع. استخدمت تلك القوالب لإنتاج 200 برشام ذو رأس مسطح مخفي بواسطة عملية الطرق الدافئ ، 100 مطروقة (برشام) بكل قالب.يتم حساب البلى التآكلي من خلال تطبيق منهجية (آلية) تتضمن قياس المقطع الجانبي للقوالب المستخدمة (المبلاة) بواسطة ماكنة قياس الأبعاد الثلاثية (CMM) بعد تعويض التشويه المرن لسطح القالب المتوقع من استخدام برنامج محاكاة بطريقة العناصر المحددة FEA(DEFORM 2DTM) لفصله عن عمق البلى.تم استخدام عمق البلى المقاس في نموذج ارجرد الرياضي (Archard’s Model) لحساب معامل البلى (K) الثابت عملياً ومقارنته بمعامل البلى (KPred.) المتوقع (النظري) بطريقة العناصر المحددة FEA لتحسين عملية الطرق من خلال اقتراح معامل بلى تآكلي (K) جديد.أظهرت النتائج النظرية توافق كبير مع النتائج العملية حيث أن أكبر فرق كان (12%) و (12.6%)لكل من القالب الغير مقسى و والقالب المقسى والمراجع على التوالي.

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