多孔介质中基质和微生物耦合输运问题的三次样条分析

本文用三次样条和全隐式逐次迭代方法,对描述多孔介质中基质-微生物耦合输运微分方程组进行数值计算,结果表明:数值求解这种具一定对流优势的非线性扩散方程,该计算方案是可行的,且获得了良好的结果。通过数值分析,对微生物在多孔介质中的传输行为有了个大概的了解,还探明了各参数对耦合系统的影响作用。     

Shooting method in singular perturbation problem of ordinary differential equations with boundary layers

By using the adaptive steplength integration scheme with a shooting technique, a rather difficult singular perturbation problem of ordinary differential equations with boundary layers can be calculated effectively. Computing examples are given in this paper which show the convergence within one iteration of the method in the case of a linear problem, the efficiency of the method for many boundary layers and turning points, especially the convenience in calculating multiple solutions. A comparison with traditional difference method is given at the end of this paper.     

ASYMPTOTIC ANALYSIS OF STABILITY PROBLEM OF PLANE POISEUILLE FLOW FOR HIGH REYNOLDS NUMBER

A study of the stabifity of plane Poiseuille flow at higher Reynolds number is made. Within a "triple-deck" structural framework, the qualitative behaviour of the eigenvalue of Orr-Sommerfeld equation is analytically obtained. The corresponding eigenfunction is formulated approximately.     

Transient spherical flow of non-newtonian power-law fluids in porous media

The transient spherical flow behavior of a slightly compressible non-Newtonian, power-law fluids in porous media is studied. A nonlinear partial differential equation of parabolic type is derived. The diffusivity equation for spherical flow is a special case of the new equation. We obtain analytical, asymptotic and approximate solutions by using the methods of Laplace transform and weighted mass conservation. The structures of asymptotic and approximate solutions are similar, which enriches the theory of one-dimensional flow of non-Newtonian fluids through porous media.     

On several problems for lateral instability of cantilever plates

The present article researches several problems about the lateral instability, of cantilever plates by means of the energy method, in which we discuss the minimum critical load of cantilever rectangular plates under a concentrated force, a uniformly distributed load, a distributed load in triangular form and a concentrated couple, respectively, when the lateral buckling takes place.     

多孔硅表面Ag层对吸附其上的若丹明B染料分子表面增强Raman散射的影响

采用溶液电镀方法在多孔硅表面制备纳米尺寸的银颗粒,测量了不同镀银多孔硅表面吸附的ＲｈＢ染料分子以及固态的ＲｈＢ染料的Ｒａｍａｎ散射谱。在相同的激发强度下,固态ＲｈＢ染料的Ｒａｍａｎ散射最弱,而镀银的多孔硅表面具有明显的增强效果（～１０＾４）。     

Echo-Planar Imaging of Porous Media with Spatial Resolution below 100 μm

A modified version of the echo-planar imaging technique incorporating a Carr–Purcell train of 180° rf pulses (PEPI) has been implemented on a standard spectrometer. It is demonstrated that artifacts in the image due to cumulative errors in the rf field can be reduced by replacing each 180° pulse by a composite sequence of three rf pulses. Artifact-free 3D images at 94 μm voxel resolution are obtained within 15 min. This technique has been applied to study the drying process in an initially water-saturated model porous medium with characteristicT^*₂of order 700 μs.     

Shapes of heaps and in silos

Experimental investigations on the shape of a heap formed in a Hele Shaw cell either on a flat base or in a two-dimensional silo are presented. We have focused our attention on the shape dependence on mass flux and initial energy of particles poured into the cell. Two kinds of granular media are considered: glass beads and sand and we shall point out their different behaviors. We described the variations of the angle of repose and of the size of the tail as a function of the experimental parameters. We also report the time evolution of the angle of repose during the formation of the heap. Received 28 September 1998 and Received in final form 20 January 1999     

多孔二氧化钛对三氯甲烷光催化氧化的影响

报道 了以多孔 二氧化钛 为光催 化剂光催 化降解 水环境中 三氯甲烷 的一些 结果． 在所选定的实验 条件下 经１５ ｈ 光照, Ｃ Ｈ Ｃｌ３ 光催 化分解率 可达８０ ％ 左右 ． 此 结果 有利 于今 后进 一步 开展实用性 光催化 净化反应 器的研制     

Basicness of Semialgebraic Sets

This paper is concerned with the problem of deciding whether a semialgebraic set S of an algebraic variety X over R is basic. Furthermore, in such a case, we decide what is the sharp number of inequalities defining S. For that, it suffices to desingularize X, as well as the boundary of S, and then ask the same question for the trace of S on its boundary. In this way, after a finite number of blowing-ups, we lower the dimension of the data and by induction we get a finite decision procedure to solve this problem. Decidability of other known criteria is also analyzed.