توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Quasi–Dynamic Stress Analysis of Connecting Rod during Operation and Stress–Time Diagram Generation
نویسنده(ها): ، ،
اطلاعات انتشار: دومین همایش موتورهای درونسوز، سال
تعداد صفحات: ۶
The motion of the connecting rod is a combination of crank–end rotation and the reciprocating motion of the piston end .The stresses acting on the connecting rod are caused by two reasons: compressive cycle cylinder pressure and inertia force. The magnitude and direction of both forces change during an operation .In this study, Quasidynamic stress analysis of a 4 stroke engine connecting rod is presented in its nominal speed. Finite Element techniques is used in this analysis. Stress–Time diagram is plotted during operation. This diagram is used for fatigue analysis. Finally the acquired diagram is compared with experimental results.<\div>

۲Two dimensional wave propagation in thick short length FGM cylinders
نویسنده(ها): ، ،
اطلاعات انتشار: دومین کنفرانس بین المللی کامپوزیت، سال
تعداد صفحات: ۶
In this paper a thick short length hollow cylinder made of functionally graded materials (FGMs) under internal impact loading is considered. The inner surface of the cylinder is pure ceramic and the outer surface is pure metal, and the material composition varies continuously along its thickness. Finite Element Method based on Rayleigh–Ritz energy formulation is applied to study the propagation of elastic waves in FG thick hollow cylinders. The Newmark direct integration method is applied to solve the time dependent equations. The time histories of displacements, stresses, wave propagation in two directions, velocities of radial stress wave propagation and natural frequencies for various values of volume fraction exponent are investigated. To compare the model with the existing results in the literature, the result of an infinite FG thick hollow cylinder under the same loading is obtained and it shows very good agreement.<\div>

۳influence of welding temperature and pressure on the mechanical properties of welding zone of polyethylene pipes welded via butt fusion method
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۸
In this research it was intended to find the optimum temperature and pressure of welding of HDPE80 pipes used in the gas industries after primary preparation of the samples welding procedure was performed via butt fusion method in four temperatures of 180,200,210 and 225 C and by exerting four different pressures of 1.3,1.5,1.7,1.9 kg\mm2 5.4,6.9,7.8 and 8.7 bar in each temperature 64 tensile test specimens were prepared according to ISO\FDIS 13953:2001 E standard and underwent tension test in accompany with 2 specimens of un welded pipes tension test results such as yield stress tensile strength elongation repture mode and width and heght of welding bead were studied the results showed that in constant temperature tensile strength has decreased by pressure increase except at 210 C where pressure increase from 1.3kg\mm2 5.4bar to 1.9 kg\mm2 8.7bar resulted in quantitative increase of tensile strength from 19.37 to 20 MPa.<\div>

۴Effects of letrozole, non–steroidal aromatase inhibitor, on serum sex steroid levels, oocyte diameter and gonadosomatic index (GSI) in rainbow trout (Oncorhynchus mykiss)
نویسنده(ها): ، ، ،
اطلاعات انتشار: IRANIAN JOURNAL OF FISHERIES SCIENCES، چهاردهم،شماره۱، Jan ۲۰۱۵، سال
تعداد صفحات: ۱۳
The objective of this study was to contribute to investigate the efficacy of letrozole, a potent non–steroidal aromatase inhibitor, on serum sex steroid levels and oocyte growth in rainbow trout females. Serum steroid levels were measured using an indirect enzyme–linked immunosorbent assay (ELISA) before and 22 days after an initial injection with 1, 2.5 mg kg–1 and subsequent weekly injection with 2.5 mg kg–1letrozole. After the last blood collection, gonad tissues were removed and oocyte diameter and GSI were determined. In all groups treated with letrozole, serum 17β– esteradiol levels (E2) decreased significantly and inversely serum 17α–20ß dihydroxy–4 pregnen– 3– one (17α–20ß–P), testosterone(T) levels increased significantly from 6 to 96 h after injection (p0.05). The lowest E2 levels, oocyte diameter and GSI were measured in the group treated weekly with 2.5 mg kg–1 letrozole (p0.05). This study demonstrates that letrozole has the potential to interfere in the synthesis of endogenous estrogens from androgens and delay gonadal development.
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