نتایج جستجو برای: thermal gradient
تعداد نتایج: 338429 فیلتر نتایج به سال:
Weather and climate parameters and their effects on crops, is one of the most effective factors in yield increase. Agro-climatic studies could be used to determine the potential of various regions and the exploit these resources to the maximum possible extent. In this study, in order to evaluate the agricultural climate of spring canola cultivation in selected stations in Hamedan province, the ...
Two microscopic transition theorems are given for the probability of nonequilibrium work performed on a subsystem of a thermal reservoir along the trajectory in phase space of the subsystem. The resultant transition probability is applied to the case of heat flow down an applied temperature gradient. A combined molecular dynamics and Monte Carlo algorithm is given for such a nonequilibrium stea...
Thermoacoustic heat engines provide a practical solution to the problem of heat management in microcircuits where they can be used to pump heat or produce spot cooling of specific circuit elements. There are basically two types of thermoacoustic engines, a prime mover where heat is converted to acoustic energy, and a heat pump or cooler where sound can pump heat up a temperature gradient. Such ...
Introduction: Interior heat flow provides essential constraints on the thermal and chemical evolution of planetary bodies. On the moon, heat flow instrument designs typically have to reach depths below the annual solar thermal wave for the Moon (2-3 m), or alternatively methods must be applied to be able to decouple the influence of the relatively large temperature gradients associated with the...
This paper is concerned with an optimal shape control problem for the stationary Navier–Stokes system. A two–dimensional channel flow of an incompressible, viscous fluid is examined to determine the shape of a bump on a part of the boundary that minimizes the viscous drag. By introducing an artificial compressibility term to relax the incompressibility constraints, we take the penalty method. T...
We investigate the effect of a radial pressure bump in a protoplanetary disk on planetesimal formation. We performed the two-dimensional numerical simulation of the dynamical interaction of solid particles and gas with an initially defined pressure bump under the assumption of axisymmetry. The aim of this work is to elucidate the effects of the stellar vertical gravity that were omitted in a pr...
This paper gives a simplified analytical description of spontaneous generation and finite amplitude saturation of sound in annular thermoacoustic engines, and also provides comparison with experiments. The model includes the precise description of thermoacoustic amplification of sound (induced by interaction between an heterogeneously heated stack of solid plates and resonant gas oscillations),...
We study diffusive transport of aqueous methane in sea sediments, which is important for formation of methane hydrate and gas deposits and has even been claimed to be principal methane transport mechanism for some geological systems. The isothermal diffusion law (Fick's law), D X = − ∇ J , which is employed in the literature for investigations on methane hydrate, is shown to significantly devia...
We present a static microfluidic device without use of hydrogel barrier for the generation of chemical gradient. The microfluidic device allows for the analysis of bacterial chemotaxis without use of hydrogel, membrane, and pump. We demonstrate a chemotactic response to attractant and repellent by measuring of dynamic change of bacterial population in detection area. In this chemotaxis assay, b...
During the long-term operation, mallets of the forging hammers are exposed to thermal fatigue due to the cyclic temperature changes and impact loads. Taking into account very high price, and a risk of buying frequently the new parts, the necessity of their reparation becomes obvious. The forging hammer mallet (Figure 1), is primarily exposed to the impact compressive loads, and partially also t...
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