نتایج جستجو برای: valves bridge and tensile tests

تعداد نتایج: 16865999  

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده زبانهای خارجی 1392

the extent to which written corrective feedback on linguistic errors can play a role in helping l2 writers improve the accuracy of their writing continues to be an issue of interest to researchers and teachers since truscott (1996) mounted a case for its abolition. while there is growing empirical evidence that written corrective feedback can successfully target some types of linguistic error (...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور - دانشگاه پیام نور استان تهران - دانشکده علوم انسانی 1391

this study sought to examine the effect of cooperative game on iranian students achievements in english alphabet learning. cooperative games are games, in which players or teams work together towards a common goal without defeating someone. the methodology used in this study was experimental. the population of the study was 60 female students from the grade one in secondary school in tabriz, ir...

Dissimilar metals friction welding of austenitic–martensitic stainless steels is commonly used in order to manufacture engine valves in the automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) valve steel rods were welded by friction welding process. The welded joint was then heat treated at 760 0C for 60 min. Mechanical prop...

2013
Woong Lim Ho-Kyung Kim

The tensile properties of materials, such as the ultimate tensile strength, yield strength, elongation and elastic modulus, are very important factors for engineering designs. However, it is not easy for students to understand and evaluate the tensile properties of materials. In this study, a small and handy tensile testing machine was designed to help students conduct tensile tests in class us...

Journal: :Journal of biomechanics 2014
Anwarul Hasan Kim Ragaert Wojciech Swieszkowski Seila Selimović Arghya Paul Gulden Camci-Unal Mohammad R K Mofrad Ali Khademhosseini

Due to the increasing number of heart valve diseases, there is an urgent clinical need for off-the-shelf tissue engineered heart valves. While significant progress has been made toward improving the design and performance of both mechanical and tissue engineered heart valves (TEHVs), a human implantable, functional, and viable TEHV has remained elusive. In animal studies so far, the implanted T...

Journal: :محیط زیست طبیعی 0
احسان عبدی استادیار گروه جنگلداری و اقتصاد جنگل، دانشکده منابع طبیعی، دانشگاه تهران، ایران باریس مجنونیان استاد گروه جنگلداری و اقتصاد جنگل، دانشکده منابع طبیعی، دانشگاه تهران حسن رحیمی استاد گروه آبیاری، دانشکده مهندسی آب و خاک، دانشگاه تهران محمود زبیری استاد گروه جنگلداری و اقتصاد جنگل، دانشکده منابع طبیعی، دانشگاه تهران قاسم حبیبی بی بالانی دانشیار دانشگاه آزاد اسلامی واحد شبستر

effects of plant roots on increasing soil shear strength depend on root tensile strength. thus, determination of root tensile strength can provide the necessary data for analyzing root-soil relations. tensile strength of plant roots varied in a wide range and have been reported from thousands to millions of mpa. the main objective of this study was to assess inter-species variations of root ten...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد گرمسار - دانشکده علوم انسانی 1391

abstract the following study, in the first place, attempted to examine the effect of less experienced teachers participation in experienced teachers classes on their own skills and teaching methodology, in the second place, attempted to find out the role of teachers training in students achievements. for this purpose, 21 efl teachers were selected according to available sampling in kish l...

Journal: :Journal of the mechanical behavior of biomedical materials 2014
A L F Soares D van Geemen A J van den Bogaerdt C W J Oomens C V C Bouten F P T Baaijens

Mathematical models can provide valuable information to assess and evaluate the mechanical behavior and remodeling of native tissue. A relevant example when studying collagen remodeling is the Ross procedure because it involves placing the pulmonary autograft in the more demanding aortic valve mechanical environment. The objective of this study was therefore to assess and evaluate the mechanica...

Journal: :Journal of the Franklin Institute 1917

Journal: :Circulation 2005
Fraser W H Sutherland Tjorvi E Perry Ying Yu Megan C Sherwood Elena Rabkin Yutaka Masuda G Alejandra Garcia Dawn L McLellan George C Engelmayr Michael S Sacks Frederick J Schoen John E Mayer

BACKGROUND An estimated 275,000 patients undergo heart valve replacement each year. However, existing solutions for valve replacement are complicated by the morbidity associated with lifelong anticoagulation of mechanical valves and the limited durability of bioprostheses. Recent advances in tissue engineering and our understanding of stem cell biology may provide a lifelong solution to these p...

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