A singular perturbation problem for periodic boundary partial differential equation

In this paper,we consider a singular perturbation elliptic-parabolic partial differentialequation for periodic boundary value problem,and construct a difference scheme.Using themethod of decomposing the singular term from its solution and combining an asymptoticexpansion of the equation,we prove that the scheme constructed by this paper convergesuniformly to the solution of its original problem with O(τ h~2).     

A difference method for singular perturbation problem of hyperbolic-parabolic partial differential equation

In this paper we constructed an exponentially fitted difference scheme for singular perturbation problem of hyperbolic-parabolic partial differential equation. Not only do we take a fitting factor in the equation, but also we put one in the approximation of second initial condition. By means of the asymptotic solution of singular perturbation problem we proved the uniform convergence of this scheme with respect to the small parameter.     

Exponential dichotomies of nonlinear discrete systems and its application to numerical analysis and computation

In this pepar we consider the upwind difference scheme of a kind of boundary value problems for nonlinear, second order, ordinary differential equations. Singular perturbation method is applied to construct the asymptotic approximation of the solution to the upwind difference equation. Using the theory of exponential dichotomies we show that the solution of an order-reduced equation is a good approximation of the solution to the upwind difference equation except near boundaries. We construct correctors which yield asymptotic approximations by adding them to the solution of the order-reduced equation. Finally, some numerical examples are illustrated.     

The asymptotic expression of the solution of the Cauchy's problem for a higher order linear ordinary differential equation when the limit equation has singularity

In this paper we consider the asymptotic expression of the solution of the Cauchy's problem for a higher order equation when the limit equation has singularity. In order to construct the asymptotic expression of the solution, the region is divided into three sub-areas. In every small region, the solution of the differential equation is different. Project supported by the National Natural Science Foundation of China     

A Conservative Difference Scheme for Conservative Differential Equation with Periodic Boundary

1　ＤｉｆｆｅｒｅｎｔｉａｌＥｑｕａｔｉｏｎａｎｄＤｉｆｆｅｒｅｎｔｉａｂｉｌｉｔｙＰｒｏｐｅｒｔｉｅｓｏｆｔｈｅＳｏｌｕｔｉｏｎＩｎｔｈｉｓｐａｐｅｒ,ｗｅｃｏｎｓｉｄｅｒｔｈｅｃｏｎｓｅｒｖａｔｉｖｅｆｏｒｍａｎｄｓｉｎｇｕｌａｒｐｅｒｔｕｒｂｅｄｏｒｄｉｎａｒｙｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｗｉｔｈｐｅｒｉｏｄｉｃｂｏｕｎｄａｒｙｖａｌｕｅｐｒｏｂｌｅｍ :Ｌｕ(ｘ) ≡ε(ｐ(ｘ)ｕ′(ｘ) )′ (ｑ(ｘ)ｕ(ｘ) )′-ｒ(ｘ)ｕ(ｘ) =ｆ(ｘ)　　( 0 <ｘ<1 ) ,( 1 )ｕ( 0 ) ≡ｕ( 1 ) ,ｌｕ≡ｕ′( 1 )…     

Uniform difference scheme for a singularly perturbed linear 2nd order hyperbolic problem with zeroth order reduced equation

In this paper a singularly perturbed linear second order hyperbolic problem with zeroth order reduced equation is discussed. Firstly, an energy inequality of the solution and an estimate of the remainder term of the asymptotic solution are given. Then an exponentially fitted difference scheme is developed in an equidistant mesh. Finally, uniform convergence in small parameter is proved in the sense of discrete energy norm.     

EXTENSION AND APPLICATION OF NEWTON''''S METHOD IN NONLINEAR OSCILLATION THEORY

In this paper we suggest and prove that Newton's method may calculate the asymptotic analytic periodic solution of strong and weak nonlinear nonautonomous systems, so that a new analytic method is offered for studying strong and weak nonlinear oscillation systems. On the strength of the need of our method, we discuss the existence and calculation of the periodic solution of the second order nonhomogeneous linear periodic system. Besides, we investigate the application of Newton's method to quasi-linear systems. The periodic solution of Duffing equation is calculated by means of our method.     

Convergence of Anisotropically Decaying Solutions of a Supercritical Semilinear Heat Equation

We consider the Cauchy problem for a semilinear heat equation with a supercritical power nonlinearity. It is known that the asymptotic behavior of solutions in time is determined by the decay rate of their initial values in space. In particular, if an initial value decays like a radial steady state, then the corresponding solution converges to that steady state. In this paper we consider solutions whose initial values decay in an anisotropic way. We show that each such solution converges to a steady state which is explicitly determined by an average formula. For a proof, we first consider the linearized equation around a singular steady state, and find a self-similar solution with a specific asymptotic behavior. Then we construct suitable comparison functions by using the self-similar solution, and apply our previous results on global stability and quasi-convergence of solutions.     

Singular perturbation of general boundary value problem for higher-order elliptic equation containing two parameters

In this paper we consider the construction of asymptotic expression of solution for general boundary value problem for higher order elliptic equation containing two parameters. By using the method of two-parameter expression, asymptotic expression of solution and estimation corresponding to the remainder term are given. These results are the extensions of [1] and [7].     

Solutions of the Time-Harmonic Wave Equation in Periodic Waveguides: Asymptotic Behaviour and Radiation Condition

In this paper, we give the expression and the asymptotic behaviour of the physical solution of a time harmonic wave equation set in a periodic waveguide. This enables us to define a radiation condition and show well-posedness of the Helmholtz equation set in a periodic waveguide.     

The application of perturbation methods to ecology

In this paper, we study the application of perturbation methods to ecology. We obtain the asymptotic solution of an ecological differential equation.     

Singular perturbation of the fourth order elliptic equation when the limit equation is elliptic-parabolic

3@1In this paper we cosider the singular perturbation of the fourth order elliptic equation-ε~2△~2u y~m(α~2u)/(αy~2) (α~2u)/(αx~2) α(x,y)-(αu)/(αy) b(x,y)(αu)/(αx) c(x,y)=0 when the limit equationis elliptic-parabolic,where εis a positive parameter,m is a positive real number,△isLaplacian operator,a.b.c are sufficiently smooth.Under appropriate condition we derivethe sufficient condition of solvability and prove the existence of solution and give auniformly valid asymptotic solution of arbitrary order.     

On the Dirichlet problem for quasi-linear elliptic equation with a small parameter

In this paper we deal with the Dirichlet problem for quasilinear elliptic equation with a small parameter at highest derivatives. In case the characteristics of the degenerated equation are curvilinear and the domain, where the problem is defined, is a bounded convex domain, we offer a method to construct the uniformly valid asymptotic solution of this problem, and prove that the solution of this problem really exists, and being uniquely determined as the small parameter is sufficiently small.     

An exponentially fitted difference scheme for the hyperbolic-hyperbolic singularly perturbed initial-boundary value problem

In this paper we discuss,an initial-boundary value problem of hyperbolic type with firstderivative with respect to x.The asymptotic solution is constructed and its uniform validityis proved under weader compatibility conditions.Then we develop an exponentially fitteddifference scheme and establish discrete energy inequality.Finally,we prove that thesolution of difference problem uniformly converges to the solution of the original problem.     

AGAIN DISCUSSING ABOUT SINGULAR PERTURBATION OF GENERAL BOUNDARY VALUE PROBLEM FOR HIGHER ORDER ELLIPTIC EQUATION CONTAINING TWO-PARAMETER

In this paper using the method of "The Two-Variable Expansion Procedure" we again discuss the construction of asymptotic expression of solution of general boundary value problem for higher order ellitptic equation containing two-parameter whose boundary condition is more general than [1]. We give asymptotic expression of solution as well as the estimation corresponding to the remainder term.     

Axially symmetric long waves on the surface of a varying-depth basin

The axially symmetric Korteweg-de Vries (KdV) equation for the case of a constant-depth basin was obtained in [1]. In the present paper we derive the axially symmetric KdV equation for a varying-depth basin. Conditions are shown for the equation obtained, under which the asymptotic behavior of its solution is described by an equation of the form $$u_t + uu_x + u_{xxx} = 0,$$ whose asymptotic behavior is well known [2].     

Numerical solution of composite left and right fractional Caputo derivative models for granular heat flow

In this paper we propose a numerical scheme based on a fractional trapezoidal method for solution of a fractional equation with composition of the left and right Caputo derivatives. The numerical results are compared with analytical solutions. We have illustrated the convergence of our scheme. Finally, we show an application of the considered equation.     

Asymptotic solution of singular perturbation problems for the fourth-order elliptic differential equations

In this paper we consider the singularly perturbed boundary value problem for the fourth-order elliptic differential equation, establish the energy estimates of the solutionand its derivatives and construct the formal asymptotic solution by Lyuternik- Vishik ’s method.Finally, by means of the energy estimates we obtain the bound of the remainder of the asymptotic solution.     

Free vibration of a class of Hill's equation having a small parameter

In this paper, we consider the initial value problem of a class of Hill’s equation having a small parameter. Using the solvable condition of boundary value problem and the stretched parameter method in the perturbation techniques, we present the method which can be applied to obtain asymptotic periodic solution of the initial value problem. As an example, we consider Mathieu equation and present its computational result.     

非线性振动的一个新的渐近解法

本文在渐近法的基础上，引进谐波平衡思想，得到了一个新的渐近解法。与传统方法相比，应用本文方法求渐近解，不必解微分方程和依靠消除永年项建立补充工程，而是将求解过程转化为一系列的代数运算。因此，本文解法便于手算，更有利于用计算机计算高阶近似。