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Article
Optimization the Resistance Spot Welding Parameters of Austenitic Stainless Steel and Aluminum Alloy Using Design of Experiment Method

Authors: Sabah Khammass Hussein --- Osamah Sabah Barrak
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 7 Part (A) Engineering Pages: 1383-1401
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This research aims to study the effect of RSW parameters on the sheerforce of the spot weldedfor two materials {AISI 304L and AA 6061-T6}with (0.5 and 0.7 mm) thickness. Three values for each welding parameters (welding current, electrode force, squeeze time and welding time) are to be used. The effect of those parameters has been analyzed by using design of experiments (DOE) in order to determine and reduce the number of the tested specimens.The experimental tests have been donethat are;shear, micro hardness tests and microstructure examination. It was found that the maximum shear force in welding of similar material AISI 304L is (F = 4.78 KN for t = 0.7 mm), while in the joint of dissimilar material (AA 6061-T6 with AISI 304L), the maximum shear force is (F = 1.42 KN for t = 0.7 mm). These values have been optimized to reach (F =5.13 KN & F =1.54 KN) respectively by using DOE. The minimum shear force was (F = 0.07 KN in t = 0.5 mm).It was found that, increasing the welding current and sheet thickness gave an increase in the shear force, but at the same time the reduction in shear force has occurred during the increasing in electrode force, squeeze time and welding time. From micro hardness tests, it was found that the maximum value of hardness was at the center of nugget zone (NZ) and it reduces slightly until reaching constant values away from nugget zone.


Article
The Influence of Caries Infiltrant Combined with and without Conventional Adhesives on Sealing of Sound Enamel (In Vitro Study)

Authors: Marwa Balasim مروة بلاسم --- Dhiaa J. N. Al-Dabagh ضياء جعفر الدباغ
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 2 Pages: 119-125
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The formation of white spot lesions around fixed orthodontic attachments is a common complicationduring and after fixed orthodontic treatment, which hinders the result of a successfully completed orthodontictreatment. The aim of the study was to assess the effectiveness of the Caries Infiltrant (ICON®) on prevention of carieson the smooth enamel surface when applied alone or combined with conventional adhesives.Materials and methods: Seventy eight human premolar enamel discs were randomly assigned to six groups (n=13).The discs were etched and treated with resins of different monomer content forming the following groups:(1)Untreated etched samples served as the negative control, (2) ICON® (DMG), (3) Adper™ SB 2 (3M ESPE), (4)Heliobond (IvoclarVivadent), (5) ICON®+ Adper™ SB 2 and (6) ICON®+ Heliobond. Specimens were subjected todemineralization by immersion in hydrochloric acid (pH 2.6) for 18 days. Calcium dissolution into the acid wasassessed by photometric test via spectrophotometer at 24 hour intervals.Results: The results revealed that, there was a highly significant difference between the sealed groups and theunsealed (untreated) one (p≤0.00) indicating that the unsealed specimens showed the highest amount of Ca ion lossamong all other groups. Additionally, there was no significant difference between untreated specimens and theICON® sealed ones. While, Heliobond decreased the Ca ion loss significantly compared to the untreated specimensand Adper™ SB 2 performed significantly better than both ICON® and Heliobond. Furthermore, the combination ofICON® with either Adper™ SB 2 or Heliobond served as the best protective measures and maintained the protectiveeffect during the whole experiment period. Therefore, within the limitations of this in vitro study, it could beconcluded that the use of Caries Infiltrant prior to the application of the tested conventional adhesives increasestheir protective effect against demineralization.


Article
Spot Welding of Galvanized Steel ASTM A653 Using Oxygen Free High Conductivity Copper Interlayer
اللحام النقطي للفولاذ الكاربوني (ASTM A653) باستخدام نحاس عالي النقاوة كطبقة وسطية

Author: Mohammed Hillan Sar
Journal: journal of kerbala university مجلة جامعة كربلاء ISSN: 18130410 Year: 2016 Volume: 14 Issue: 1 Pages: 63-72
Publisher: Kerbala University جامعة كربلاء

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Abstract

The effect of spot welding parameters (Current and Applied Load) are studied in welding of galvanized steel specimens. Three values of current 9600, 11000 and 12300 AMP and load of 350, 400, 450 kg are used. The results indicate that the shear force improve with increasing the current and decreasing the load. The optimum shear force is achieved with current of 12300 AMP and load of 350 kg. Those parameters is used to weld steel (with and without galvanize layer) using the OFHC copper as interlayer with different thickness (0.1, 0.2 and 0.3mm). The results show that OFHC as interlayer reduce the shear force.

تم دراسة تأثير متغيرات لحام النقطة (التيار وحمل مسلط ) على عينات من الفولاذ المغلون . اختيرت ثلاث قيم من التيار ( 9600, 11000، 12300 أمبير) وثلاث قيم من حمل مسلط ( 350 , 400 ، 450 كغم ) للحام العينات . اظهرت النتائج ازدياد قوة القص بزيادة التيار وصولا الى 12300 امبير وحملا مسلطاً عند 350 كغم. استخدمت هذه المتغيرات للحام العينات المغلونة وغير المغلونة ( بعد ازالة طبقة الزنك) باستعمال طبقة رقيقة من النحاس عالي النقاوة كمعدن حشو وباسماك (0.1، 0.2 ، 0.3 ملم ). بينت النتائج ان استخدام معدن الحشو ساعد على خفض قوة القص.


Article
A Comparative study between the two interferon gamma releasing assays in the diagnosis of pulmonary tuberculosis
المقارنة بين فحصي أطلاق الانترفيرون جاما في تشخيص التدرن الرئوي

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Abstract

Objectives: To examine and compare the diagnostic value of Interferon gamma releasing assay (IGRAs) (T- SPOT TB and Qunati FERON Gold in Tube) in the diagnosis of pulmonary tuberculosis.Materials and methods: The study included 40 patients with active pulmonary tuberculosis. They were attendance of Respiratory Health Care Centers in Mosul City for the period from March to December 2013. From each patient a sputum sample was collected and processed for culture on Löwenstein-Jensen (L-J media). Twelve milliliters (ml) of blood from each patients was collected (10 ml collected in heparinised tube for T SPOT TB and 2 ml in QFT-GIT special tubes)Results: From the total 40 patients with positive AFB staining 37 (92.5%) were culture positive. The specificity of both IGRAs were 100% . The sensitivity of T- SPOT TB test was 91.89%, while the QFT-GIT sensitivity was 86.49%. The positive predictive value of both IGRAs was 100%. The negative predictive value of T SPOT TB was 50 %, while that of QFT-GIT was 37.5 %. There was a moderate degree of agreement between the T -SPOT TB and QFT–GIT in (82.5%, k=0.54, 95%CI). The results of the two IGRAs are not affected by BCG vaccination status of TB patients.Conclusions: The IGRAs could provide a supplementary information as part of diagnostic work-up for tuberculosis diagnosis but it is important to note that a negative IGRA does not rule out active TB . Moreover, and of the two IGRAs, QFT GIT is more convenient to adopted for diagnostic use.

الأهداف: اختبار ومقارنة المقدرة التشخيصية لفحصي اطلاق الانترفيرون جاما(T SPOT TB and FERON Gold in Tube) في تشخيص التدرن الرئوي.المواد وطريقة الدراسة: شملت الدراسة على 40 مريضا مصابا بالتدرن الرئوي النشط الذين كانوا يراجعون مراكز الرعاية الصحية التنفسية في مدينة الموصل للفترة من شهر آذار إلى شهر كانون الأول لعام 2013. تم جمع عينة قشع من كل مريض وزراعتها على الوسط الزرعي Löwenstein-Jensen (L-J). أيضا تم جمع 12 مل من الدم من كل مريض, 10 مل وضعت في أنابيب اختبار تحوي على الهيبارين لغرض اجراء فحص T-SPOT TBو 2 مل في أنابيب مخصصة لفحص QuantiFERON.النتائج: من أصل 40 مريض ايجابي للصبغة المقاومة للحموضة 37(92.5%) كانت نتيجة الاستنبات ايجابية. وبالنسبة لدرجة خصوصية فحصي إطلاق الانترفيرون جاما وصلت إلى 100% وقدرت حساسيةT-SPOT TB ب 91.89%. في حين بلغت حساسية QFT-GIT 86.4%. كانت القيمة التنبؤية الايجابية للفحصين 100%. اما القيمة التنبؤية السلبية لفحصT SPOT TB كانت50% بينما لفحص QFT-GIT كانت 37.5% كما أن درجة الاتفاق بين فحصي اطلاق الانترفيرون جاما كانت متوسطة(82.5 %,k=0.45) في حالة التدرن. كما اثبت أن نتيجة فحصي إطلاق الانترفيرون جاما لا تتأثر بلقاح BCGفي مرضى التدرن.الاستنتاجات: يمكن استخدام فحصي اطلاق الانترفيرون جاما كجزء من العملية التكميلية لتشخيص التدرن لكن من المهم ملاحظة ان النتيجة السالبة للفحصين لا يستبعدان الإصابة بمرض التدرن و أن من بين الفحصين, فحصQFT-GIT أكثر ملائمة للاستخدام.


Article
Editorial :NEW HUMAN BODY PARTS DISCOVERED

Author: Hayder J. Mubarak حيدر جواد مبارك
Journal: IRAQI JOURNAL OF MEDICAL SCIENCES المجلة العراقية للعلوم الطبية ISSN: P16816579,E22244719 Year: 2016 Volume: 14 Issue: 3 Pages: 197-199
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

Reports about new discoveries in human anatomy could help in the progress of medical care in term of diagnosis and management. Among the many of these was the hidden system of vessels discovered in the human brain in 2015, the anterolateral ligament of the knee joint describe in 2013, Dua's layer discovered in the human cornea in 2013, and the description of the anatomic structure of the G-spot done in 2012. These new part of the human body may be more properly considered as newly discovered variations in the human body.Keywords: Anatomy, human discoveries, brain lymphatics, knee joint, Dua's layer, G-spot.


Article
NUMERICAL AND EXPERIMENTAL INVESTIGATIONS OF TRANSIENT TEMPERATURE DISTRIBUTION IN FRICTION STIR SPOT WELDING OF ALUMINUM ALLOY AA6061
الدراسات العددية والعملية لتوزيع درجة الحرارة العابرة في اللحام الاحتكاكي النقطي لسبيكة الألومنيوم AA6061

Authors: Asst. Prof. Dr. Mohsin N. Hamzah --- Asst. Prof. Dr. Sadeq H. Bakhy --- Mujtaba A. Fliayyh
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2016 Volume: 9 Issue: 3 Pages: 388-407
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

AbstractFriction stir spot welding (FSSW) is a powerful and superior alternative to resistance spotwelding and riveting for fabrication of aluminum sheet metal structures. The objective is tostudy the variation of transient temperature in a friction stir spot welded plate of AA6061Aluminum Alloy. Numerical and experimental investigations were performed to study thetemperature distribution during this process. Two thermocouples (type K) were placed at twospecified locations from the pin hole to measure the transient temperature during FSSWwelding process. Numerically, 3D finite element model was built using ANSYS workbenchVer.15 to simulate the thermal model during welding. The torque and axial load weremeasured experimentally to determine the coefficient of friction, which used with the otherparameters, to find the applied heat flux for the welding process. The temperaturedistributions of the specimens welded by three tools with different pins; i.e. cylindrical,tapered and triangular, at constant other FSSW parameters, were investigated and comparedwith the experiment temperature measured using the thermocouples to validate the results.The results show that the temperature produced from the welded specimen with cylindricalpin shape has the highest temperature distributions due to high axial load and torque ascompared with other tool pin profiles. Also the results show good agreement betweennumerical and experimental with a percentage error (-3.09 – 7.83) %.

الخلاصة:طريقة اللحام الاحتكاكي النقطي هي طريقة لحام متطورة نسبيا وتستخدم كطريقة بديلة وفعالة للحام الكهربائي وطريقة الوصلات اللتان يستخدمان للحام الالمنيوم. ان الهدف الرئيسي من هذا البحث هو اجراء دراسة عملية ونظرية لتوزيع الحرارة المتولدة خلال اللحام الاحتكاكي النقطي لسبيكة الألومنيوم AA6061-T6 وذلك لفهم الظاهرة الفيزيائية الناتجة من خلال اختراق اداة اللحام للعينات المراد لحمها. تم استخدام ثرموكبلين نوع K ثبتت على مسافة4 mm و 7 mm من مركز ادارة اللحام لقياس الحرارة المتولدة اثناء اللحام. نظريا تم انشاء موديل باستخدام (ANSYS workbench Ver.15) لمحاكاة توليد الحرارة. في هذا الموديل تم قياس الحمل المحوري والعزم المتولدة اثناء عملية اللحام تجريبيا لانهما يستخدمان في حساب معامل الاحتكاك الذي يستخدم مع متغيرات اخرى لايجاد تدفق الحرارة في عملية اللحام.في هذه الدراسة تم تغيير شكل اداة اللحام اسطواني ومخروطي ومثلثي وبثبوت عوامل اللحام الاحتكاكي النقطي الاخرى.اظهرت النتائج ان توزيع درجة الحرارة المتولدة باستخدام اداة لحام ذات شكل اسطواني هي الاعلى في توزيع درجة الحرارة و ذلك بسبب ارتفاع الحمل المحوري والعزم المسلط عند مقارنتها بادوات اللحام الاخرى. وكذلك هناك تقارب جيد بين انتائج النظرية العملية و بنسبة خطا بين (-3.09-7.83)%

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