A secondary semantics for Second Order Intuitionistic Propositional Logic

In this paper we propose a Kripke‐style semantics for second order intuitionistic propositional logic and we provide a semantical proof of the disjunction and the explicit definability property. Moreover, we provide a tableau calculus which is sound and complete with respect to such a semantics. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multiple periodic solutions for second order systems with changing sign potential

This paper deals with the multiplicity of solutions of a second order nonautonomous system. We extend a previous result of the author relaxing the assumptions on the sign of the potential.     

用两单参数李群求3阶自治系统的首次积分

在较一般的条件下,对3阶自治系统给出利用系统所接受的两个单参数李群的生成元计算首次积分的方法．     

BOUNDARY VALUE PROBLEM FOR SECOND ORDER IMPULSIVE DIFFERENTIAL EQUATION

The author employs the method of upper and lower solutions together with the monotone iterative technique to obtain the existence theorem of minimal and maximal solutions for a boundary value problem of second order impulsive differential equation.     

解析Dirichlet级数的准确零(R)级

本文研究了右半平面内解析Dilrichlet级数的准确零(R)级,减弱了已有结果的条件,得到了更强的结论并简化了原证明．     

A stable second‐order mass‐weighted upwind scheme for unstructured meshes

In this paper, an original second‐order upwind scheme for convection terms is described and implemented in the context of a Control‐Volume Finite‐Element Method (CVFEM). The proposed scheme is a second‐order extension of the first‐order MAss‐Weighted upwind (MAW) scheme proposed by Saabas and Baliga (Numer. Heat Transfer 1994; 26B :381–407). The proposed second‐order scheme inherits the well‐known stability characteristics of the MAW scheme, but exhibits less artificial viscosity and ensures much higher accuracy. Consequently, and in contrast with nearly all second‐order upwind schemes available in the literature, the proposed second‐order MAW scheme does not need limiters. Some test cases including two pure convection problems, the driven cavity and steady and unsteady flows over a circular cylinder, have been undertaken successfully to validate the new scheme. The verification tests show that the proposed scheme exhibits a low level of artificial viscosity in the pure convection problems; exhibits second‐order accuracy for the driven cavity; gives accurate reattachment lengths for low‐Reynolds steady flow over a circular cylinder; and gives constant‐amplitude vortex shedding for the case of high‐Reynolds unsteady flow over a circular cylinder. Copyright © 2005 John Wiley & Sons, Ltd.     

Accuracy assessment to applying 20-node solid elements to pressurized composite shells

A factorial analysis is conducted to explore the impact of five factors — aspect ratio, radius-to-thickness ratio, material anisotropy, fiber angle and integration order on the finite element accuracy, with regard to the application of 20-node isoparametric solid elements to clamped composite cylindrical shells subjected to internal pressure. The maximum radial displacement at the central cross-section is employed as the indicator of accuracy. Results from finite element methods were compared with closed-form solutions. Aspect ratio, radius-to- thickness ratio, and integration order are significant main effects as predicted for isotropic materials. Material anisotropy shows no significant main effect, while the fiber angle does have strong impact on the finite element accuracy. In addition to four influential main effects, some multiple-factor interactions are shown to have significant influences on the finite element accuracy. The analysis is limited to the linear elastic range.     

Zero temperature phase transitions in spin-ladders: Phase diagram and dynamical studies of Cu2(C5H12N2)2Cl4>

In a magnetic field, spin-ladders undergo two zero-temperature phase transitions at the critical fields H_c1 and H_c2. An experimental review of static and dynamical properties of spin-ladders close to these critical points is presented. The scaling functions, universal to all quantum critical points in one-dimension, are extracted from (a) the thermodynamic quantities (magnetization) and (b) the dynamical functions (NMR relaxation). A simple mapping of strongly coupled spin ladders in a magnetic field on the exactly solvable XXZ model enables to make detailed fits and gives an overall understanding of a broad class of quantum magnets in their gapless phase (between H_c1 and H_c2). In this phase, the low temperature divergence of the NMR relaxation demonstrates its Luttinger liquid nature as well as the novel quantum critical regime at higher temperature. The general behavior close these quantum critical points can be tied to known models of quantum magnetism. Received: 13 March 1998 / Received in final form and Accepted: 21 July 1998     

The Order Properties of r-compact Operators on Banach Lattices

We present here that F（E,F）, the space of all r-compact operators from E into F, is a generalised sublattice of L^r（E, F） for arbitary Banach lattices E and F, and that the characterization of the regular norm on F（E, F） is order continuous. Some conditions for F（E, F） to be a KB-space or a band in .L（E, F） are also provided.