Explicit finite-difference procedures for elastodynamic analysis of layered media

Summary Explicit finite-difference procedures are proposed to simulate the elastodynamic response of layered media. To avoid large numerical dispersion and dissipation, different grid sizes are used for different material layers so that the CFL number in each layer can be set to one in the limit. The master-slave technique is applied to deal with the mismatch of grids along the material interface. The interface can be either bonded or unbonded. The dynamic contact between two layers along an unbonded interface is also considered. Numerical examples are presented. Received 4 August 1997; accepted for publication 24 April 1998     

The Dirichlet,Neumann and Mixed Boundary Value Problems of the Theory of Elasticity in n-Dimensional Domains with Boundaries Containing Closed Cuspidal Edges

The Dirichlet, Neumann and mixed problems of statics of the theory of elasticity for anisotropic homogeneous media are studied in n-dimensional (n ≧ 2) domains with boundaries containing closed cuspidal edges. Theorems of the existence and uniqueness of solutions of these problems in the Besov and Bessel potential spaces are obtained. Smoothness of solutions in a closed domain occupied by elastic medium is investigated.     

一类Moran测度的Lq-谱

此文考虑了一类Moran分形，在其生成过程中每一阶的压缩比及压缩比的个数可以是不相同的，证明了支撑在此类Moran分形上的Moran测度的L^q-谱的存在性．     

Fractal characteristics of critical and localized states in incommensurate quantum systems

Incommensurate quantum systems with two competing periodicities exhibit metallic (with Bloch-type extended wave functions), insulating (with exponentially localized wave functions) as well ascritical (with fractal wave functions) phases. An exact renormalization method, which takes into account the inherent incommensurability, is used to obtain the phase diagram of various quantum models for the two-dimensional electron gas and for quantum spin chains in a magnetic field. In this approach, the scaling properties of the fractal eigenstates are characterized by a fixed point or a strange invariant set of the renormalization flow. One of our novel results is the existence of self-similar fluctuations in the localized states once the exponentially decaying envelope is factorized out. In almost all cases under investigation here, the universality classes can be broadly classified as those of the nearest-neighbor square or triangular lattices.     

α模型中不固定多重数下的阶乘矩、粒子数关联矩

利用二维相空间自仿射分形的随机级联α模型,采用蒙特卡罗模拟的方法,研究了阶乘矩､粒子数关联矩在不固定多重数下,对应于多重数相对起伏强度n_f的依赖关系,得到:阶乘矩、粒子数关联矩依赖于多重数相对起伏n_f,但间歇指数一般不依赖于n_f,当n_f较小时这种依赖性得以消除.     

Mathematical Analysis of a Transport Model with Unbounded Heat Capacities

We consider a problem of nuclear waste contamination in the basement. We derive a detailed model describing the simultaneous transport of brine, radionuclides and heat in a compressible flow through a porous medium. It leads to a nonlinear system of fully coupled partial differential equations. Using a fixed point approach, we prove existence of physically relevant weak solutions.      

Spontaneous radial capillary impregnation across a bank of aligned micro-cylinders. Part II: Experimental investigations

This paper presents an experimental approach to study the capillary impregnation of a liquid across an array of parallel micro-cylinders. The technique presented successfully validates the theoretical findings of part I, and provides a methodology to calculate the fill time and the overall capillary impregnation dynamics for any arbitrary cylindrical sample made of aligned micro-cylinders, by taking into account the role of the trapped gas, which opposes and slows down the inward capillary flow.     

Modified method of characteristics in transient radiation transfer

This paper presents the modified method of characteristics for simulating multidimensional transient radiative transfer in emitting, absorbing and scattering media. The method is based on the method of characteristics that follows photons along their pathlines. It makes use of a fixed set of points, and unlike the conventional method of characteristics, it follows the photons backward in space. Test problems involving diffuse irradiation in 1-D and 3-D participating media and collimated irradiation in 1-D participating media were considered. The results show good agreement with analytical and numerical solutions reported in literature. The scheme is fast and was able to capture the sharp discontinuities associated with the propagation of a radiation front in transient radiation transport.     

Light guides with thermohydrodynamic gas lenses (TGL)

Summary Light guides with thermohydrodynamic gas lenses (TGL) are studied from both the optical and the therno-fluid-dynamic point of view.

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Riassunto Guide di luce con lenti a gas termoidrodinamici (TGL) sono studiate sia dal punto di vista ottico che da quello termofluidodinamico.

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