A dielectric constant measurement setup has been developed to measure dielectric constant of liquids using AT89C55WD microcontroller. A modified operational amplifier based AC Schering Bridge network is used to compute capacitance and hence calculate dielectric constant of liquids. This instrument system permits recording of dielectric constant of liquids at various concentrations and temperatu...

the grain aphid, sitobion avenae (hemiptera: aphididae) is one of the injuriously important pests of wheat and praon volucre (hymenoptera: braconidae) is one of its major parasitoids in iran. in this research, thermal requirements of the grain aphid and its parasitoid were evaluated at six constant temperatures (10, 15, 20, 25, 27.5 and 30 °c), 60 ± 5 % relative humidity and a photoperiodicity ...

In this paper, Wavelet Collocation Method has been used to solve nonlinear fin problem with temperature dependent thermal conductivity and heat transfer coefficient. Thermal conductivity of fin materials varies any type so that we consider thermal conductivity as the general function of temperature.  Here we consider three particular cases, where we assume that thermal conductivity is constant,...

a theoretical solution is presented for the forced convection heat transfer of a viscoelastic fluid obeying the giesekus constitutive equation in a concentric annulus under steady state, laminar, and purely tangential flow. a relative rotational motion exists between the inner and the outer cylinders, which induces the flow. a constant temperature was set in both cylinders, in this study. the f...

Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu3NMx (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. Th...

Extended surfaces are one of the most important approaches to increase the heat transfer rate. According to the Fourier law, the heat transfer increases by increasing the contact surface of body and fluid. In this study, the effect of heat transfer has been investigated on two sets of engineered porous fins, in which the balls with different materials are sintered together. The fluid flow throu...

Energy and exergy concepts come from thermodynamics laws and are applicable to all fields of science and engineering. This study considers numerical simulations of combustion of hydrogen with air in a constant pressure environment and exergy terms according to first and second laws analysis using homemade code. Chemical kinetic model includes 20 reactions and 9 species.  At the first stage of p...