ON STABILITY OF SOLUTIONS OF CERTAIN FOURTH-ORDER DELAY DIFFERENTIAL EQUATIONS

By the use of the Liapunov functional approach, a new result is obtained to ascertain the asymptotic stability of zero solution of a certain fourth-order non-linear differential equation with delay. The established result is less restrictive than those reported in the literature.     

A regularity theorem for minimizers of quasiconvex integrals

Summary We prove C ^1, partial regularity for minimizers of functionals with quasiconvex integrand f(x, u, Du) depending on vector-valued functions u. The integrand is required to be twice continuously differentiable in Du, and no assumption on the growth of the derivatives of f is made: a polynomial growth is required only on f itself.     

Kantorovich theorem for variational inequalities

Kantorovich theorem was extended to variational inequalities by which the convergence of Newton iteration, the existence and uniqueness of the solution of the problem can be tested via computational conditions at the initial point.     

FC_空间中的参数型KKM定理及其应用

The paper first proves a characteristic property in FC-spaces. By the use of the connectedness of sets, a parametric type of KKM theorem is then established in noncompact FC-spaces by introducing a linear ordered space. As a consequence, some recent results, such as noncompact minimax inequalities, saddle point theorem, and section theorem, are improved. The results generalize the corresponding results in the literatures.     

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

In this paper we construct the finite-difference scheme for the singularly perturbedboundary value problem for the fourth-order elliptic differential equation on the basis ofpaper[1],and prove the uniform convergence of this scheme with respect to the smallparameterεin the discrete energy norm,Finally,we give a numerical example.     

Second-order accurate difference method for the singularly perturbed problem of fourth-order ordinary differential equations

In this paper, we construct a uniform second-order difference scheme for a class of boundary value problems of fourth-order ordinary differential equations. Finally, a numerical example is given.     

A regularity theory for a general class of quasilinear elliptic partial differential equations and obstacle problems

Communicated by J. Serrin     

Asymptotic stability for impulsive functional differential equations

In this paper, we investigate the stability of a class of impulsive functional differential equations by using Lyapunov functional and Jensen＇s inequality. Some new stability theorems are obtained. Examples are given to demonstrate the advantage of the obtained results.     

The corner solution for quasilinear differential equation with two parameters

I.IntroductionWeconsiderinthispaperboundaryvalueproblemofquasilineardifferentialequationby# pi(x,y)y' g(x,y)=0,a相似文献   

A pseudospectral approach applicable for time integration of linearized N-S operator that removes pole singularity and physically spurious eigenmodes

This paper addresses a modified singularity removal technique for the eigenvalue or optimal mode problems in pipe flow using a pseudospectral method. The current approach results in the linear stability operator to be devoid of any unstable physically spurious modes, and thus, it provides higher numerical stability during time-based integration. The correctness of the numerical operator is established by calculating the known eigenvalues of pipe Poiseuille flow. Subsequently, the optimal modes are determined with Farrell's approach and compared with the existing literature. The usefulness of this approach is further demonstrated in the time-based numerical integration of the linearized Navier-Stokes operator for the adjoint method–based optimal mode determination. The numerical scheme is implemented with the radial velocity-radial vorticity formulation. Even number of Chebyshev-Lobatto grid points are distributed over the domain r∈[−1,1] omitting the centerline, which also efficiently provides higher resolution near the wall boundary. The boundary conditions are imposed with homogeneous wall boundary conditions, whereas the analytic nature of a proper set of base functions enforces correct centerline conditions. The resulting redundancy introduced in the process is eliminated with the proper usage of parity.     

A new uniqueness theorem of the linear thermo-elastic dynamics on unbounded domains

In the present paper, the uniqueness of the solution to the initial boundary value problem of the linear thermo-elastic dynamics on unbounded domains is obtained under less restrictive conditions, including abandoning the positive semi-definiteness of the elasticity tensor and boundness of the material tensor and restrictions on the acoustic tensor and the coupled tensor, and the results in [1] are refined. The conclusion here is valid for the case on bounded domains and the linear elastic dynamics on unbounded domains, hence the results in [2–4] are refined too. Abandoning the positive semi-definiteness of elasticity tensor permits that the uniqueness of the kinetic process is still valid for deformation of the wider materials, especially for the case that there are phase-transition during deformation process provided that the constitutive equations are unchanged in forms. The project is partially supported by The Youth Foundtion of Science of the Higher-Education of Shanghai and YFNSC (No. 19802012)     

弹性力学轴对称问题的有限元线法

给出了解弹性力学空间轴对称问题的有限元线法的基本理论。该法包括了２－４条结线的等参数单元，沿结线方向的两点边值问题采用插值矩阵法解之。算例表明，本法具有良好的收敛性和较高的计算精度。     

On the explicit differential operator formulae for the Oldroyd rate type constitutive equation

We have established the conditions under which the implicit Oldroyd type constitutive equation is equivalant to a differential type constitutive equation. Physical interpretations of these conditions are given. Finally some explicit forms for Maxwell type and Oldroyd type constitutive equations are given as illustrations.     

Strong convergence theorem for relatively nonexpansive mapping and inverse-strongly-monotone mapping in a Banach space

In this paper, we introduce an iterative sequence for finding a common element of the set of fixed points of a relatively nonexpansive mapping and the set of solutions of the variational inequality for an inverse-strongly-monotone mapping in a Banach space. Then, we show that the sequence converges strongly to a common element of the two sets. Our results improve and extend the corresponding results reported by many others.     

A representation theorem for volume-preserving transformations

A general solution is presented for the partial differential equation ∂u/∂x=k(x), where u and x are n-vector fields, ∂u/∂x denotes the Jacobian of the transformation x→u and k(x) is a scalar-valued function. The solution for the case k(x)=1 is of special interest because it furnishes a representation theorem for volume-preserving transformations in an n-dimensional space. Such a representation for the case n=2 was obtained by Gauss. The solution for n=3, presented here, furnishes a representation for isochoric (volume-preserving) finite deformations, which are important in the mechanics of highly deformable incompressible solid materials.     

A simple and efficient fourth-order approximation solution for nonlinear dynamic system

In the present paper, based on the classical Magnus expansion, a simple and efficient fourth-order integrator is given for an arbitrary nonlinear dynamic system, which can preserve the qualitative properties of the exact solution. The proposed method can be considered an averaging technique, and only requires evaluations of exponentials of simple unidimensional integrals. Finally, the numerical examples are given to demonstrate the validity and effectiveness of the method of this paper.     

On the control problem for a compound wheeled vehicle

A compound transport vehicle with one steerable wheel is considered as a controlled mechanical system with nonholonomic constraints. A control system for this system is synthesized within the framework of the kinematic approximation. A procedure is proposed to synthesize a robust controller for the system. The efficiency of this procedure is demonstrated with an example __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 11, pp. 105–112, November 2007.