توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Modelling of mechanical behavior of porous sintered timing wheel in contact with chain wheels
نویسنده(ها): ،
اطلاعات انتشار: پنجمین همایش موتورهای درونسوز، سال
تعداد صفحات: ۹
The mechanical properties of sintered timing wheel in contact with chain wheels were analysed using Finite Element Methods (FEM), in which the timing wheel is modelled as a metal powder. The mechanical properties of sintered timing wheel were investigated as a function of sintered density. Tensile strength and Young’s modulus increased with a decrease in porosity. Current methods of calculating gear contact stresses use Hertz’s equations, which were originally derived for contact between sintered timing wheel and chain wheels. The results of the 2D dimensional FEM analyses from ANSYS are presented. The relationship between relative density of P\M steels and mechanical behavior is also obtained from FEM and compared with the experimental data. Good agreement between the experimental and FEM results is observed, which demonstrates that FEM can capture the major features of the P\M steels behaviour during loading. This indicates that the FEM model is accurate.<\div>

۲Application of lattice Boltzmann method for simulating nanofluids
نویسنده(ها): ،
اطلاعات انتشار: اولین کنفرانس ملی علوم و فناوری نانو، سال
تعداد صفحات: ۴
A suspension of ultrafine particles in a fluid base that leads to little or no penalty in pressure drop called 'nanofluid'. Therefore, it is distinguishable from adding suspended solid particles in order of millimeters or micrometers into the fluid, because they may cause some severe problems, such as clogging of the flow in the channels, settling the particles rapidly and pressure drop. Recently, nanofluids are considered in fluid mechanicsfor their great potential for heat transfer enhancement than the traditional solid–liquid mixture. Inherent irregular and Brownian motion of nanofluids makes traditional theoretical methods such as Navier–Stokes fail to simulate the flow and energy field. In this paper, the lattice Boltzmann methodintroduced as a powerful technique to simulating the nanofluids even in complex geometries. Moreover, the strength of the lattice Boltzmann method is its computational simplicity and its locality.<\div>

۳Deterio0ration Of Refregration Cycle Performance With Irreversible Vapor Compression At Ambient Temprature
نویسنده(ها): ،
اطلاعات انتشار: سومین کنفرانس تخصصی ترمودینامیک، سال
تعداد صفحات: ۵
It is known that room temperature affects the performance of refrigerators mainly by increased inputs of heat in the refrigerated compartments by the decrease in the condensation of the refrigerant, these two effects reduce the ability Nominal cooling of the device. This issue is particularly important for good preservation of food and medicines. In this work, we consider a cycle refrigeration vapor compression applied to an irreversible refrigerator freezer modeled using the concept of thermodynamics in finite time. The coefficient of performance is maximized and the parameters of the thermal conductances sized according to data from manufacturer for a business model of 160 liters of Class C freezer; the effects of the variation of ambient temperature on performance are then evaluated.<\div>

۴Modeling Of Aqueous Solutions Electrolyte Type 3–1
نویسنده(ها): ، ،
اطلاعات انتشار: سومین کنفرانس تخصصی ترمودینامیک، سال
تعداد صفحات: ۶
To model the activity coefficients of aqueous solutions of 3–1 electrolytes, we took again the original theory of Pitzer concerning the excess Gibbs energy for the aqueous solutions of electrolytes. The model was applied for 11 systems including 3–1 electrolytes. The performance of this model was compared with other models existing in the literature. The results show that the model of Pitzer can represent the mean ionic activity coefficients of 3–1 electrolytes in aqueous solutions with a standard deviation comparable with the other models and in the majority of the cases better than the others.<\div>

۵Numerical Simulation of Unsteady One–Dimensional Dam–Break Flows Using TVD MacCormack Scheme
نویسنده(ها): ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی عمران، سال
تعداد صفحات: ۸
Dam break phenomenon is still of paramount important issue in the field of hydraulic engineering. Predicting the critical conditions due to dam–break flows indicates more field studies requirement. The MacCormack numerical scheme is a classical second order explicit scheme for the simulation of unsteady one–dimensional dam–break flows. It is well known that classical second order schemes show oscillatory behavior near discontinuities and can generate or maintain a shock in the solution. In this paper, the classical MacCormack scheme is presented and extended to a finite difference predictor–corrector TVD (Total Variation Diminishing) scheme by implementing a conservative dissipation term to the last step of classical version. MacCormack’s scheme with and without TVD correction is used to simulate one–dimensional dam–break problem. The accuracy of the computed solutions are verified with an analytic solution and experimental data. It is found that using TVD scheme, any unphysical oscillation in the vicinity of strong gradients in the numerical solution is avoided. Furthermore this algorithm improved the performance of the MacCormack scheme and for the one– dimensional case, a satisfactory agreement between computed and experimental results obtained.<\div>

۶A channel shortening technique based on Neural Network with Perceptron Learning Rule for OFDM System in multipath fading channel
نویسنده(ها): ، ،
اطلاعات انتشار: دومین کنفرانس ملی ایده های نو در مهندسی برق، سال
تعداد صفحات: ۴
in multicarrier systems, channel shortening was designed to compensate inter–symbol and inter–carrier interference due to delay spread channel. This paper suggests a new channel shortening technique based Neural Network with Perceptron learning rule for multicarrier systems in multipath fading channels. simulation and analytical results show the performance of the new technique and compare it to previous channel shortening designs in terms of bit error rate (BER) for a multicarrier system<\div>

۷The Environmental Kuznets Curve for CO2 Emission: Does It Matter for Asian countries?
نویسنده(ها): ، ، ،
اطلاعات انتشار: کنفرانس سراسری الکترونیکی محیط زیست و انرژی ایران، سال
تعداد صفحات: ۸
Considerable interest has focused on the possible existence of an environmental Kuznets curve. The environmental Kuznets curve hypothesis admits the existence of an inverted U–shaped relationship between economic growth, generally approximated by GDP per capita, and environmental degradation. Despite the abundance of empirical literature on the environmental Kuznets curve, so far little study has been dealt with the relationship among developing Asian countries. Hence, we have therefore tried to extract this curve for these countries by focusing on the CO2 emission as an indicator of environmental degradation. For this aim, we have applied the econometric techniques of panel data over the period ranging from 1990 to 2011. By estimating a quadratic relationship between per capita income and pollution and by employing GLS method, we are able to deduce a U–shaped relation between income and CO2 emission.<\div>

۸Prediction of improved cyclone system efficiency: Multi objective optimization by hybrid approach based on the genetic algorithm and artificial neural network
نویسنده(ها): ، ، ،
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۱۲
An integrated process which is proposed for improving dust removal efficiency of cyclones in another paper is considered here for simulation by Artifitial Neural Networks (ANNs) and hybrid ANN and Genetic Algorithm (GA). The process incorporates of two cyclones coupled with a specially designed cylindrical chamber, which includes a rotating tube inside it with air–impinging nozzles drilled on the peripheral surface of the tube. The chamber includes a tube with nozzles on itsperipheral surface from which jet–impingement flow throws the particles nearer to wall of the chamber. Efficiency of the jet–impingement chamber, as a function of the feed flow rate, recycleflow rate, jet–impingement flow rate as well as the jet–impingement tube rotational speed has beentested on a pilot scale apparatus of the process for fitting and simulating by ANN and hybrid ANN and GA. ANN and hybrid ANN and GA were able to accurately capture the non–linear characteristics of the chamber even for a new condition that has not been used in the training process (tested data).<\div>

۹3D FREE VIBRATION ANALYSIS OF FG RECTANGULAR SANDWICH PLATE
نویسنده(ها): ، ، ،
اطلاعات انتشار: اولین همایش ملی تکنیک های نوین در تجهیزات و مواد آزمایشگاهی صنعت نفت ایران، سال
تعداد صفحات: ۹
This study presents free vibration behaviour of two type of simply supported sandwich plates based on the three dimensional theory of elasticity. The core layer of one type is functionally graded (FG) with the isotropic face sheets where as in second type the core layer is isotropic with the face sheets FG material. The effective material properties of FG layers are estimated to vary continuously through the thickness direction according to a power law distribution in terms of the volume fractions of the constituents. The differential governing equations are solved by using Fourier series expansion along the in plane directions, state space technique across the thickness direction. The combination of constitutive equations for transverse isotropy composite layer, the linear relations between the displacements and strain and equations of motion If body forces are ignored are used. Accuracy and exactness of the present approach is validated by comparing the numerical results with the published results. It can be observed that the present formulation yields exact and accurate results compared to the other solutions presented. Finally the influences of volume fraction, width to thickness ratios and power law indices on the vibration behavior of plate are investigated.<\div>

۱۰A study on growth parameters, blood factors and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in underground brackish and freshwater
اطلاعات انتشار: IRANIAN JOURNAL OF FISHERIES SCIENCES، دوازدهم،شماره۴، oct ۲۰۱۳، سال
تعداد صفحات: ۷
In this research, growth rate, blood parameters and proximate composition of rainbow trout (Oncorhynchus mykiss) cultured in brackish and freshwater were evaluated. Two treatments (brackish and freshwater) in 3 replications were investigated. Six 1.5 m³ fiberglass tanks were used for this experiment, containing 180 rainbow trout specimens with average weight of 47.2±0.1g. Feeding rate in treatments was about 3% of body weight based on water temperature and fish biomass. Total length and weight of fish were measured in 15 days intervals. After 135 days of culture period, some fish samples were transferred to the Lab. Blood were directly collected from the heart. Muscle composition was analyzed for proximate composition. The results showed that the body weight of samples in brackish water was increased significantly after 45 days of culture period. Blood factors including WBC, RBC, Hb, Hct, MCV, MCH, MCHC, lymphocyte, thrombocyte and concentration of K+ ions in fish cultured in brackish water showed a significant increase (P0.05). Muscle composition analysis showed a significant increasing (p0.05) in fat and dry matter in freshwater treatment, while moisture was significantly higher in brackish water (P0.01)

۱۱Effects of oral administration of Zataria multiflora essential oil on some blood and serum parameters in Acipenser persicus
اطلاعات انتشار: IRANIAN JOURNAL OF FISHERIES SCIENCES، دوازدهم،شماره۴، oct ۲۰۱۳، سال
تعداد صفحات: ۹
In order to does this study, 150 Persian sturgeons having 75g mean weight transferred to 500 liter tanks. After dividing the fishes into two groups (experimental and control), the fingerlings fed by concentrate food that contained different levels of Zataria multiflora essential oil (15, 25, 50, 100 g\kg) for 8 weeks. Finally, sampling carried out on blood and serum of fishes. After preparing the samples based on standard methods, hematology and serology studies, performed. The results showed significant difference in mean of monocytes between experimental and control groups (P0.05). In treatment 25g\kg, monocyte count was more than other treatments. But there were no significant differences in mean and standard deviation of other white blood cells. The results of serologic studies showed no significant differences in serum indices (C3, C4 and total protein) (P>0.05), but there is significant difference in mean and standard deviation of albumin. So that, the average in treatments 15 and 25g\kg and control group was more than treatments 50 and 100g\kg of Zataria multiflora essential oil.
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