排序方式: 共有111条查询结果,搜索用时 15 毫秒
71.
关于分布参数控制系统能控性的一个注 总被引:1,自引:1,他引:0
SHI Jin-e ZHANG Zhi-ping 《数学季刊》2005,20(4):435-437
This paper gives the relation between the precise controllabilities of two distribution parameter systems. 相似文献
72.
We propose and analyze a posteriori energy-norm error estimates for weighted interior penalty discontinuous Galerkin approximations of advection-diffusion-reaction equations with heterogeneous and anisotropic diffusion. The weights, which play a key role in the analysis, depend on the diffusion tensor and are used to formulate the consistency terms in the discontinuous Galerkin method. The error upper bounds, in which all the constants are specified, consist of three terms: a residual estimator which depends only on the elementwise fluctuation of the discrete solution residual, a diffusive flux estimator where the weights used in the method enter explicitly, and a non-conforming estimator which is nonzero because of the use of discontinuous finite element spaces. The three estimators can be bounded locally by the approximation error. A particular attention is given to the dependency on problem parameters of the constants in the local lower error bounds. For moderate advection, it is shown that full robustness with respect to diffusion heterogeneities is achieved owing to the specific design of the weights in the discontinuous Galerkin method, while diffusion anisotropies remain purely local and impact the constants through the square root of the condition number of the diffusion tensor. For dominant advection, it is shown, in the spirit of previous work by Verfiirth on continuous finite elements, that the local lower error bounds can be written with constants involving a cut-off for the ratio of local mesh size to the reciprocal of the square root of the lowest local eignevalue of the diffusion tensor. 相似文献
73.
In this paper, some equivalent theorems on simultaneous approximation for combinations of Gamma operators by weighted moduli of smoothness ωφλ^r(f,t)wφ^s(0≤λ≤1)are given. The relation between derivatives of combinations of Gamma operators and smoothness of derivatives of functions is also investigated. 相似文献
74.
In this paper we investigate several solution algorithms for the convex fea- sibility problem(CFP)and the best approximation problem(BAP)respectively.The algorithms analyzed are already known before,but by adequately reformulating the CFP or the BAP we naturally deduce the general projection method for the CFP from well-known steepest decent method for unconstrained optimization and we also give a natural strategy of updating weight parameters.In the linear case we show the connec- tion of the two projection algorithms for the CFP and the BAP respectively.In addition, we establish the convergence of a method for the BAP under milder assumptions in the linear case.We also show by examples a Bauschke's conjecture is only partially correct. 相似文献
75.
Starting from the extended mapping approach and a linear variable separation method, we find new families of variable separation solutions with some arbitrary functions for the (3+1)-dimensionM Burgers system. Then based on the derived exact solutions, some novel and interesting localized coherent excitations such as embedded-solitons, taper-like soliton, complex wave excitations in the periodic wave background are revealed by introducing appropriate boundary conditions and/or initial qualifications. The evolutional properties of the complex wave excitations are briefly investigated. 相似文献
76.
Ground State Energy Calculations of Isoelectronic Series of He in Double-Zeta Approximation Using Coulomb Potential with Noninteger Indices 下载免费PDF全文
Using formulae for one- and two-electron integrals of Coulomb interaction potential fk (r) = r^-k with non-integer indices k established by one of the authors with the help of complete orthonormal sets of ψ^α-exponential-type orbitals (α = 1, 0,-1,-2,…), we perform the calculations for isoelectronic series of the He atom containing nuclear charges from 2 to 10, where k = 1 - μ (-1 〈 μ 〈 0). For this purpose we have used the double-zeta approximation, the configuration interaction and coupled-cluster methods employing the integer-n Slater-type orbitals as basis sets. It is demonstrated that the results of calculations obtained are better than the numerical Hartree-Fock values. 相似文献
77.
Application of Complete Orthonormal Sets of Ψα-Exponential-Type Orbitals to Accurate Ground and Excited States Calculations of One-Electron Diatomic Molecules Using Single-Zeta Approximation 下载免费PDF全文
The applicability of the complete orthonormal sets of ψ^a-exponential-type orbitals introduced by one of the authors to the study of electronic structure of one electron diatomic molecules is demonstrated using single-zeta approximation. As an example of application, tile calculations have been performed for o, 7r and 5 states of one electron homo- and hetero-nucleac diatomic molecules H+2 and Hell2+, respectively. The calculation results are presented. The values for these molecules obtained in eight-digit accuracy ace close to the results of solution presented in literature. 相似文献
78.
ZhouChangyin HeGuoping 《高校应用数学学报(英文版)》2004,19(2):229-238
In this paper, two-stage stochastic quadratic programming problems with equality constraints are considered. By Monte Carlo simulation-based approximations of the objective function and its first (second)derivative,an inexact Lagrange-Newton type method is proposed.It is showed that this method is globally convergent with probability one. In particular, the convergence is local superlinear under an integral approximation error bound condition.Moreover, this method can be easily extended to solve stochastic quadratic programming problems with inequality constraints. 相似文献
79.
A.R.Khan N.Hussain A.B.Thaheem 《分析论及其应用》2004,20(2):189-198
We pressent new Ky Fan type best approximation theorems for a discontinuous multivalued map onmetrizable topological vector spaces and hyperconvex spaces. In addition, fixed point results are derivedfor the map studied. Our work generalizes severl results in approximation theory. 相似文献
80.
A.Al-Shuaibi F.Al-Rawjih 《分析论及其应用》2004,20(1):28-34
Given the Laplace transform F(s) of a function f(t), we develop a new algorithm to find an approximation to f(t) by the use of the classical Jacobi polynomials. The main contribution of our work is the development of a new and very effective method to determine the coefficients in the finite series expansion that approximation f(t) in terms of Jacobi polynomials. Some numerical examples are illustrated. 相似文献