GLOBAL UNIQUENESS IN THE INVERSE ACOUSTIC SCATTERING PROBLEM WITHIN POLYGONAL OBSTACLES

§1. Introduction √ Let k ∈R, λ> 0 and i = ?1. We consider an acoustic scattering problem by animpenetrable obstacle D ? R2: ?u k2u = 0, in R2 \ D, …     

A Lindström theorem for intuitionistic first-order logic

We extend the main result of [1] to the first-order intuitionistic logic (with and without equality), showing that it is a maximal (with respect to expressive power) abstract logic satisfying a certain form of compactness, the Tarski union property and preservation under asimulations. A similar result is also shown for the intuitionistic logic of constant domains.     

Domain structure and birefringence studies on a 0.91Pb(Zn1/3Nb2/3)O3 ‐0.09PbTiO3 single crystal

Domain structure and phase transition sequence of 0.91PZN‐0.09PT single crystal, grown from high temperature solution, have been analysed using polarised light microscopy. The domain structure of (001)_cub cut single crystal exhibit co‐existence of rhombohedral and tetragonal phases. The sequence and phase transition temperatures have been determined from temperature dependence of birefringence. Birefringence measurements during heating and cooling reveal a first order nature of phase transition between rhombohedral (R3m) and tetragonal (P4mm). The birefringence was measured with accuracy of 10^‐3. However, dielectric measurement does not provide any evidence of R3m ‐ P4mm phase transition. It is shown that in‐situ analysis of domain structure and phase transition can be used as non‐destructive analytical tool for determination of local composition and phase transition sequence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Weighted fractional Sobolev spaces as interpolation spaces in bounded domains

We characterize the real interpolation space between a weighted $L^p$ space and a weighted Sobolev space in arbitrary bounded domains in ${\mathbb{R}}^n$, with weights that are positive powers of the distance to the boundary.     

一类椭圆方程的边界唯一延拓性

本文主要讨论了一类二阶椭圆方程Lu=-△u+Vu=0的弱解在连通凸区域边界上的唯一延拓性,并且证明了文[4]中提出的猜测在本文的情形同样成立.