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91.
The problem of finding the potential of a translational flow through a system of circular or spherical layers in a porous medium obeying Darcy's law is considered. The permeability coefficients change stepwise across the interface. The method is based on deriving special recurrence relations which give a rational dependence of the potentials on the permeability coefficients suitable for specific calculations. 相似文献
92.
A.L. Vasiliev E.A. Stepantsov Z.G. Ivanov E. Olsson K. Verbist G. Van Tendeloo 《Interface Science》1997,5(4):223-230
The structure of the artificial grain boundaries in Al2O3 bicrystals withY3Al5O12 and Y-stabilizedZrO2 (Y-ZrO2) intermediate layers was studiedwith high resolution electron microscopy, electron diffraction and energydispersive X-ray analysis. TheY3Al5O12 intermediate layer wasfound to be polycrystalline with three different orientation relationshipsbetween the 2O3 and theY3Al5O12. The structure of theY3Al5O12/2O3 interfaces is described.Also2O3 bicrystals with an Y-ZrO2/2O3/Y-ZrO2/2O3/Y-ZrO2intermediate layer, prepared at two different temperatures, werestudied.Recry stallization of the intermediate layers occurred during thesolid phase intergrowth of the 2O3 bicrystalsparts and only an Y-ZrO2 layer was found as intermediatelayer. The misorientation between the consecutive Y-ZrO2grains was less than 1.5°. Misfit dislocations and atomic height stepsdecorate the Y-ZrO2/2O3interface. 相似文献
93.
CFD Calculation of Turbulent Flow with Arbitrary Wall Roughness 总被引:1,自引:0,他引:1
David Apsley 《Flow, Turbulence and Combustion》2007,78(2):153-175
94.
Thermal Stability and Molecular Ordering of Organic Semiconductor Monolayers: Effect of an Anchor Group 下载免费PDF全文
Dr. Andrew O. F. Jones Philipp Knauer Prof. Roland Resel Dr. Andreas Ringk Prof. Peter Strohriegl Dr. Oliver Werzer Prof. Michele Sferrazza 《Chemphyschem》2015,16(8):1712-1718
The thermal stability and molecular order in monolayers of two organic semiconductors, PBI‐PA and PBI‐alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI‐PA, are reported. In situ X‐ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI‐PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI‐alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate. 相似文献
95.
《Journal of separation science》2017,40(12):2654-2661
A specially designed long open tubular capillary column (50 μm internal diameter and 112 cm effective length) was prepared by fabrication of a thin three‐component co‐polymer layer on the inner surface of silica capillary. A pretreated silica capillary was reacted with 4‐(chloromethyl)phenyl isocyanate in the presence of dibutyltin dichloride as catalyst followed by sodium diethyl dithiocarbamate. Then a thin polymer layer was made on the inner surface of capillary by reversible addition‐fragmentation transfer polymerization of styrene, N‐phenylacrylamide, and methacrylic acid. A carefully adjusted formulation of reaction mixture and elaborated procedures were adopted to secure formation of the co‐polymer layer of enhanced separation performance. The co‐polymer immobilized open tubular capillary column was used for the separation of a synthetic mixture of five peptides and excellent separation efficiency (over 1.7 million per column) was obtained in the capillary electrochromatography mode. Such excellent separation efficiencies of ca. 1 m column have not been obtained in the isocratic elution mode so far. The column was also used for separation of the peptides in the liquid chromatography mode to show very good separation efficiency (average 286 700 per column). 相似文献
96.
We consider the solidification of a binary alloy in a mushy layer subject to Coriolis effects. A near-eutectic approximation and large far-field temperature is employed in order to study the dynamics of the mushy layer with a Stefan number of unit order of magnitude. The weak nonlinear theory is used to investigate analytically the Coriolis effect in a rotating mushy layer for a new moderate time scale proposed by the author. It is found that increasing the Taylor number favoured the forward bifurcation. 相似文献
97.
横观各向同性层状场地对入射SH波的响应分析 总被引:11,自引:0,他引:11
本文采用横观各向同性层状弹性模型模拟半空间之上的层状了,推导了在SH波入射时这种场地土的动力刚度矩阵及基岩输入运动时场地呼应的计算公式,算例表明,横观各向同性层状场地与各向同性层状了频谱特性有明显的区别,应当引起重视。 相似文献
98.
A. Yu. Vasil’ev Yu. D. Chashechkin 《Journal of Applied Mechanics and Technical Physics》2006,47(3):314-323
The energy and force characteristics of periodic internal wave beams in a viscous exponentially stratified fluid are analyzed.
The exact solutions of linearized problems of generation obtained by integral transformations describe not only three-dimensional
internal waves but also the associated boundary layers of two types. The solutions not containing empirical parameters are
brought to a form that allows a direct comparison with experimental data for generators of various types (friction, piston,
and combined) of rectangular or elliptic shape. The stress tensor and force components acting on the generator are given in
quadratures. In the limiting cases, the solutions are uniformly transformed to the corresponding expressions for the problems
in a two-dimensional formulation.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 12–23, May–June, 2006 相似文献
99.
Jialai Wang 《Journal of the mechanics and physics of solids》2004,52(4):891-905
An improved method based on the first-order shear deformable plate theory is developed to calculate the energy release rate and stress intensity factor for a crack at the interface of a bi-layer structure. By modeling the uncracked region of the structure as two separate Reissner-Mindlin plates bonded perfectly along the interface, this method is able not only to take into account the shear deformation in the cracked region, but also to capture the shear deformation in the uncracked region of the structure. A closed form solution of energy release rate and mode decomposition at the interface crack is obtained for a general loading condition, and it indicates that the energy release rate and stress intensity factor are determined by two independent loading parameters. Compared to the approach based on the classical plate theory, the proposed method provides a more accurate prediction of energy release rate as well as mode decomposition. The computational procedures introduced are relatively straightforward, and the closed form solution can be used to predict crack growth along the layered structures. 相似文献
100.
V. N. Zyryanov 《Fluid Dynamics》2005,40(6):885-896
Using the method of matched asymptotic expansions, an analytical solution of the balance equation for turbulence energy is constructed for a shallow basin (sea) in which the fluid depth does not exceed the Stokes layer thickness. In this case, a gradient-viscous balance is established with the turbulent viscosity being balanced mainly by the pressure gradient. It is shown that nonlinear boundary layers attributable to turbulence energy diffusion are formed near the bottom and the free surface (or ice). In the neighborhood of the point of maximum flow velocity (if this maximum is attained inside the flow), a nonlinear internal boundary layer also develops. Outside these layers, the turbulence energy generation is in the first approximation balanced by the energy dissipation. Asymptotic solutions for the boundary layers are constructed. 相似文献