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排序方式: 共有3383条查询结果,搜索用时 31 毫秒
981.
Adopting a two-temperature and two-velocity model, appropriate to a bidisperse porous medium (BDPM) proposed by Nield and
Kuznetsov (2008), the classical steady, mixed convection boundary layer flow about a horizontal, isothermal circular cylinder
embedded in a porous medium has been theoretically studied in this article. It is shown that the boundary layer analysis leads
to expressions for the flow and heat transfer characteristics in terms of an inter-phase momentum parameter, a thermal diffusivity
ratio, a thermal conductivity ratio, a permeability ratio, a modified thermal capacity ratio, and a buoyancy or mixed convection
parameter. The transformed partial differential equations governing the flow and heat transfer in the f-phase (the macro-pores)
and the p-phase (the remainder of the structure) are solved numerically using a very efficient implicit finite-difference
technique known as Keller-box method. A good agreement is observed between the present results and those known from the open
literature in the special case of a traditional Darcy formulation (monodisperse system). 相似文献
982.
The effect of power law index parameter of the non-Newtonian fluid on free convection heat and mass transfer from a vertical
wall is analyzed by considering double dispersion in a non-Darcy porous medium with constant wall temperature and concentration
conditions. The Ostwald–de Waele power law model is used to characterize the non-Newtonian fluid behavior. In this case a
similarity solution is possible. The variation of heat and mass transfer coefficients with the governing parameters such as
power law index, thermal and solutal dispersion parameters, inertia parameter, buoyancy ratio, and the Lewis number is discussed
for a wide range of values of these parameters. 相似文献
983.
用溶出伏安法测定蛋白胨细胞生长液中易变形态铜 总被引:1,自引:0,他引:1
采用阳极阶梯溶出伏安法 ,测定了蛋白胨细胞生长液中的易变形态铜 ,并获得了总铜量中易变形态的摩尔分数以及易变形态的表观稳定常数。通过使用交换介质法 ,较好消除了由于蛋白胨细胞生长液中各种氨基酸或其它组分吸附在汞膜表面而引起的干扰 相似文献
984.
A series of CoxAg1-x nanostructured granular films have been prepared by ion beam sputtering and annealed at 100, 250, 400, 500℃. The optical constants, the complex dielectric function and magneto-optical Kerr parameters were measured at room temperature. For the samples having low Co compositions, the strong Kerr effect enhancement is observed around the Ag plasma edge. With an increase in annealing temperature, the resonance-like peaks appear in the Kerr rotation, and the peak positions are shifted toward the low photon energy region. From the analysis of the numerical calculations, it is concluded that the magneto-optical Kerr effect enhancement (MOKE) is due to the presence of the steep plasma edge. 相似文献
985.
多孔复合介质周期结构热传导和质扩散问题的多尺度数值方法 总被引:11,自引:3,他引:8
本文针对一类复杂的多孔复合介质的热传导和质扩散问题,给出具体的多尺度渐近展开公式,并在此基础上设计了有限元算法格式,它是宏观和细观相结合的数值方法。理论分析和数值实验均表明:多尺度数值方法对求解多孔复合介质周期结构的热传导和质扩散问题是可行的和有效的。 相似文献
986.
K. L. Pan 《辐射效应与固体损伤》2013,168(2):167-178
Abstract Nonlocal stresses of a screw dislocation near a free surface in a semi-infinite hexagonal medium are investigated by a surface dislocation model. The nonlocal image force on the screw dislocation due to the existing free surface is also obtained. All classical singularities for the stress and image force are eliminated. The maxima of the stress and image force are evaluated. A zero point of the stress is found, which predicts that different states of the shear stress exist simultaneously near the dislocation. The appearance of a zero value at the free surface and a maximum of the dislocation image force can be used to explain the existence of the dislocation free zone. 相似文献
987.
Fumiko Akagi Masaki MukohMasafumi Mochizuki Junko UshiyamaTakuya Matsumoto Harukazu Miyamoto 《Journal of magnetism and magnetic materials》2012,324(3):309-313
Thermally assisted magnetic recording (TAR) with bit-patterned media was investigated by micromagnetic simulation. The media were assumed to be FePt layers. The effective head-field margin as well as the increase in temperature margin and down-track shift margin was investigated. Conditions of the head and medium that lead to a recording density beyond 5 Tb/in2 were proposed. 相似文献
988.
989.
990.
In this article, the non-isothermal Poiseuille flow and its stability in a vertical annulus filled with porous medium are investigated. The flow is induced by external pressure gradient and buoyancy force due to linearly varying inner wall temperature. The non-Darcy model along with Boussinesq approximation has been used. The Chebyshev spectral-collocation method has been adopted to solve the governing equations related to basic flow as well as its stability. Special attention is given to understand the effect of curvature parameter of the annular geometry on the flow, heat transfer rate and stability of the stably stratified flow. A comprehensive numerical experiment indicates that reducing gap between two concentric cylinders decreases the heat transfer rate as well as the maximum magnitude of the flow velocity. It stabilizes the flow which has been shown through stability analysis. Furthermore, appropriateness of the Forchheimer term in the momentum equation has been examined by investigating the flow regime as well as its stability in the presence and absence of Forchheimer term. Finally, it has been found from the energy analysis at critical point that the thermal-buoyant instability is the only mode of instability for the considered range of different parameters. 相似文献