ANALYTIC BOUNDARY VALUE PROBLEMS ON CLASSICAL DOMAINS

In this paper analytic boundary value problems for some classical domains in Cn are developed by using the harmonic analysis due to L.K. Hua. First it is discussed for the version of one variable in order to induce the relation between the analytic boundary value problem and the decomposition of function space L2 on the boundary manifold. Then an easy example of several variables, the version of torus in C2, is stated. For the noncommutative classical group L1, the characteristic boundary of a kind of bounded symmetric domain in C4, the boundary behaviors of the Cauchy integral are obtained by using both the harmonic expansion and polar coordinate transformation. At last we obtain the conditions of solvability of Schwarz problem on L1, if so, the solution is given explicitly.

A New Analytical Approach for Solving Nonlinear Boundary Value Problems in Finite Domains

Based on the homotopy analysis method (HAM), we propose an analytical approach for solving the following type of nonlinear boundary value problems in finite domain. In framework of HAM a convenient way to adjust and control the convergence region and rate of convergence of the obtained series solutions, by defining the so-called control parameter h , is provided. This paper aims to propose an efficient way of finding the proper values of h.Such values of parameter can be determined at the any order of approximations of HAM series solutions by solving of a nonlinear polynomial equation. Some examples of nonlinear initial value problems in finite domain are used to illustrate the validity of the proposed approach. Numerical results confirm that obtained series solutions agree very well with the exact solutions.

General Boundary Value Problems for Nonlinear Uniformly Elliptic Equations in Multiply Connected Infinite Domains

This article discusses the general boundary value problem for the nonlinear uniformly elliptic equation of second order in D (0.1) and the boundary condition,(0.2) in a multiply connected infinite domain D with the boundary T. The above boundary value problem is called Problem G. Problem G extends the work [8] in which the equation (0.1) includes a nonlinear lower term and the boundary condition (0.2) is more general. If the complex equation (0.1) and the boundary condition (0.2) meet certain assumptions, some solvability results for Problem G can be obtained. By using reduction to absurdity, we first discuss a priori estimates of solutions and solvability for a modified problem. Then we present results on solvability of Problem G.

PoincaréProblem for Nonlinear Elliptic Equations of Second Order in Unbounded Domains

In [1], I. N. Vekua propose the Poincaré problem for some second order elliptic equations, but it can not be solved. In [2], the authors discussed the boundary value problem for nonlinear elliptic equations of second order in some bounded domains. In this article, the Poincaré boundary value problem for general nonlinear elliptic equations of second order in unbounded multiply connected domains have been completely investigated. We first provide the formulation of the above boundary value problem and corresponding modified well posed-ness. Next we obtain the representation theorem and a priori estimates of solutions for the modified problem. Finally by the above estimates of solutions and the Schauder fixed-point theorem, the solvability results of the above Poincaré problem for the nonlinear elliptic equations of second order can be obtained. The above problem possesses many applications in mechanics and physics and so on.

Infinitely Many Radially Symmetric Solutions to Superlinear Boundary Value Problems in Annular Domains

In this paper we show that a class of superlinear boundary value problems in annular domains have infinitely many radially symmetric solutions. The result is obtained without other restrictions on the growth of the nonlinearities. Our methods rely on the energy analysis and the phase plane angle analysis of the solutions for the associated ordinary differential equations.

各向异性问题的多子域区域分解算法

在自然边界归化原理的基础上,构造了一种无界凹角区域上各向异性问题的多子域非重叠区域分解算法,这是两子域的非重叠区域分解法的推广.本文给出了多子域区域分解算法的离散和变分形式,利用等价性理论,通过详细的理论证明说明此算法是收敛的,且与网格参数h无关.

外区域上Tricomi方程初边值问题解的破裂

该文在n维空间中研究了一类外区域上的非线性Tricomi方程的初边值问题.通过引入适当的泛函并利用Kato引理,得到问题的解会在有限时间内破裂,并给出解的生命跨度的上界估计.

A Fast Cartesian Grid-Based Integral Equation Method for Unbounded Interface Problems with Non-Homogeneous Source Terms

This work presents a fast Cartesian grid-based integral equation method for unbounded interface problems with non-homogeneous source terms.The unbounded interface problem is solved with boundary integral equation methods such that infinite boundary conditions are satisfied naturally.This work overcomes two difficulties.The first difficulty is the evaluation of singular integrals.Boundary and volume integrals are transformed into equivalent but much simpler bounded interface problems on rectangular domains,which are solved with FFT-based finite difference solvers.The second one is the expensive computational cost for volume integrals.Despite the use of efficient interface problem solvers,the evaluation for volume integrals is still expensive due to the evaluation of boundary conditions for the simple interface problem.The problem is alleviated by introducing an auxiliary circle as a bridge to indirectly evaluate boundary conditions.Since solving boundary integral equations on a circular boundary is so accurate,one only needs to select a fixed number of points for the discretization of the circle to reduce the computational cost.Numerical examples are presented to demonstrate the efficiency and the second-order accuracy of the proposed numerical method.

ANALYSIS OF FDTD TO UPML FOR MAXWELL EQUATIONS IN POLAR COORDINATES

An FDTD system associated with uniaxial perfectly matched layer（UPML） for an electromagnetic scattering problem in two-dimensional space in polar coordinates is considered.Particularly the FDTD system of an initial-boundary value problems of the transverse magnetic（TM） mode to Maxwell＇s equations is obtained by Yee＇s algorithm,and the open domain of the scattering problem is truncated by a circle with a UPML.Besides,an artificial boundary condition is imposed on the outer boundary of the UPML.Afterwards,stability of the FDTD system on the truncated domain is established through energy estimates by the Gronwall inequality.Numerical experiments are designed to approve the theoretical analysis.

EXISTENCE OF POSITIVE SOLUTIONS TO SUBLINEAR SECOND-ORDER PERIODIC BOUNDARY VALUE PROBLEM

In this paper, we consider a second-order periodic boundary value problem. By the topological degree theory and fixed point index theory, we prove the existence of positive solutions which gives the relationship between the first positive eigenvalue of the associated eigenvalue problem and the behavior of the nonlinear term of the system.

SOME GENERAL THEOREMS AND GENERALIZED AND PIECEWISE GENERALIZED VARIATIONAL PRINCIPLES FOR LINEAR ELASTODYNAMICS

From the concept of four-dimensional space and under the four kinds of time limit conditions, some general theorems for elastodynamics are developed, such as the principle of possible work action, the virtual displacement principle, the virtual stress-momentum principle, the reciprocal theorems and the related theorems of time terminal conditions derived from it. The variational principles of potential energy action and complementary energy action, the H-W principles, the H-R principles and the constitutive variational principles for elastodynamics are obtained. Hamilton's principle, Toupin's work and the formulations of Ref. [5], [17]-[24] may be regarded as some special cases of the general principles given in the paper. By considering three cases: piecewise space-time domain, piecewise space domain, piecewise time domain, the piecewise variational principles including the potential, the complementary and the mixed energy action fashions are given. Finally, the general formulation of piecewise variational principles is derived. If the time dimension is not considered, the formulations obtained in the paper will become the corresponding ones for elastostatics.

INITIAL BOUNDARY VALUE PROBLEMS FOR PARABOLIC EQUATIONS IN LIPSCHITZ CYLINDERS

The initial-Dirichlet and initial-Neumann problems in Lipschitz cylinders are studied forthe general second order parabolic equations of constant coefficients with squarely integrableboundary data. By layer potential method developed in the past decade, the author provesthat the double layer potential and the single layer potential operators are invertible and henceobtains the solvability of the initial boundsry value problems. Also, the solutions can berepresented by these operators.

EXISTENCE OF POSITIVE SOLUTIONS TO SINGULAR SUBLINEAR SEMIPOSITONE NEUMANN BOUNDARY VALUE PROBLEM

The existence of positive solutions to a singular sublinear semipositone Neumann boundary value problem is considered. In this paper,the nonlinearity term is not necessary to be bounded from below and the function q(t) is allowed to be singular at t = 0 and t = 1.

ON THE PLANE STRESS BOUNDARY VALUE PROBLEM OF QUASI-STATIC LINEAR THERMOELASTICITY

he stress boundary value problem of quasi-static linear thermoelasticity is discussed. The thermoelastic systems on bounded simply-connected domain is decoupled. The decoupled temperature equation is investigated by using accurate estimation and the contractive mapping principle. Representation of solution of the field equation is obtained, and some solvability results are proved.

环形区域上含梯度项的椭圆边值问题的径向解

讨论了环形区域Ω={x∈R^(N)|r_(1)<|x|<r_(2)}上含梯度项的椭圆边值问题{-Δu=f(|x|,u,|∇u|),x∈Ω,u|∂Ω=0径向解的存在性与唯一性,其中N≥3,f:[r_(1),r_(2)]×R×R^(+)→R连续。在不假定非线性项f非负的情形下,当f(r,u,η)关于η满足Nagumo型条件时,运用上下解方法和截断函数技巧,获得了径向解的存在性。进一步,证明了在一定条件下径向解的唯一性。

An Infinite Horizon Linear Quadratic Problem with Unbounded Controls in Hilbert Space

An infinite horizon linear quadratic optimal control problem for analytic semigroup with unbounded control in Hilbert space is considered.The state weight operator is allowed to be inddefinite while the control weight operator is coercive.Under the exponential stabilization condition,it is proved that any optimal control and its optimal trajectory are continuous.The positive real lemma as a necessary and sufficient condition for the unique solvability of this problem is established.The closed-loop synthesis of optimal control is given via the solution to the algebraic Riccati equation.

MULTIGRID ALGORITHM FOR THE COUPLING SYSTEM OF NATURAL BOUNDARY ELEMENT METHOD AND FINITE ELEMENT METHOD FOR UNBOUNDED DOMAIN PROBLEMS

In this paper, some V-cycle multigrid algorithms are presented for the coupling system arising from the discretization of the Dirichlet exterior problem by coupling the natural boundary element method and finite element method. The convergence of these multigrid algorithms is obtained even with only one smoothing on all levels. The rate of convergence is found uniformly bounded independent of the number of levels and the mesh sizes of all levels, which indicates that these multigrid algorithms are optimal. Some numerical results are also reported.

Linear quadratic problem with unbounded control in Hilbert spaces

A finite horizon linear quadratic optimal control problem in Hilbert space is considered, in which the controls are unbounded and the state weight operators are allowed to be indefinite and not necessarily smoothing. It is proved that any optimal control and optimal trajectory are continuous. The closed_loop synthesis for optimal control is given via the solution to Fredholm integral equation and also the solution to Riccati integral equation, which exists under some mild conditions.

Clifford分析中无界域上正则函数的边值问题

在引入修正Cauchy核的基础上,讨论了无界域上正则函数的带共轭值的边值问题：a(t)Φ+(t)+b(t)Φ+(t)+c(t)Φ-(t)+d(t)Φ=g(t)．首先给出了无界域上正则函数的Plemelj公式,然后利用积分方程方法和压缩不动点原理证明了问题解的存在唯一性．

Clifford分析中无界域上正则函数带Haseman位移的边值问题

该文在引入修正的Cauchy核的基础上,讨论了Clifford分析中无界域上正则函数带Haseman位移的边值问题.首先给出了无界域上Cauchy型积分的Plemelj公式,再利用积分方程方法和压缩不动点定理证明了问题解的存在唯一性.