توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Irradiation Effects on the Behavior of 3–D Free Vibrations of Solid and Hollow Circular Cylinders via p–Ritz Method
نویسنده(ها): ، ، ،
اطلاعات انتشار: شانزدهمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۷
In this study, a general approach is presented for solving the free vibration analysis of solid and hollow circular cylinders exposed to the rradiation. It is obvious that Irradiation by neutrons can affect mechanical properties of material. In order to examine the influence of this phenomenon on the dynamic behavior of solid and hollow circular cylinders, it is mathematically simulated by assuming Young’s modulus and density are exponentially varied as a new function of position and time. The analysis procedure is based on the linear, small strain, and three–dimensional elasticity theory. Finally, the various values of natural frequencies of the above cylinder under the irradiation are graphically presented for different inner–outer radius ratio, thickness–radius ratio and irradiation parameters.<\div>

۲Feasibility of using hydrocarbon mixtures as refrigerants in domestic and commercial refrigeration appliances
نویسنده(ها): ، ،
اطلاعات انتشار: هشتمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۶
Ozone depleting and warming potential of CFC and HCFC refrigerants led the developed countries to agree on Montreal protocol, according to which the production and consumption of these substances must be prohibited before 2010. In this relation, a great number of efforts has been taken to find suitable substitutes for Ozone Depleting Substances (ODS). R–134a, which is a HFC, has been found to be an optimum solution for short time substitution. Unfortunately, the global warming potential (GWP) of this gas is much more than CFCs. Several research projects have shown that hydrocarbons such as propane, butane, and isobutane are very good substitutes for CFCs. These natural refrigerants have zero Ozone depleting potential and negligible GWP. In this paper, the possibility of using HCs as substitutes for CFCs has been investigated, and a computer simulation of a small refrigeration cycle with various refrigerants has been made by use of a revised version of GCAP. The results show that a hydrocarbon mixture with 40% propane (R–290), 50% butane (R–600) and 10% i–butane (R–600a) is the most suitable alternative
refrigerant with the best performance among all other hydrocarbon mixtures investigated.<\div>
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