求解粘性系数的迭代方法及其收敛性

求解粘性系数的迭代方法及其收敛性丛文相（黑龙江大学，哈尔滨１５００８０）１９９１年８月３０日收到．１９９２年８月２５日收到第一次修改稿．１９９２年１２月４日收到第二次修改稿．一、引言研究地震正、反问题时，一般把地球假设为完全弹性体，而实际地球介质并非...     

论多目标分式规划

论多目标分式规划徐增堃（浙江师范大学数学系，金华３２１００４）基金项目：浙江省教委自然科学基金资助课题．１９９０年１０月２９日收到，１９９１年１０月５日收到第一次修改稿．１９９２年９月７日收到第二次修改稿，１９９３年２月１３日收到第三次修改、压缩稿．...     

Hiriart—Urruty问题与Clarke广义梯度的若干性质

Ｈｉｒｉａｒｔ—Ｕｒｒｕｔｙ问题与Ｃｌａｒｋｅ广义梯度的若干性质刘晓华（湖南财经学院信息系，长沙４１００７９）１９８８年５月２６日收到，１９９２年４月２９日收到第一次修改稿，１９９３年４月２３日收到第二次修改稿．一、引言Ｈｉｒｉａｒｔ－Ｕｒｒｕｔｙ等...     

成败型寿命试验──GLM和E-M算法

成败型寿命试验──ＧＬＭ和Ｅ－Ｍ算法王学仁云南省应用数学研究所石磊（云南大学统计系，昆明６５００９１）１９９０年１０月１５日收到．１９９２年８月２４日收到修改稿．一、引言在可靠性分析中，成败型寿命试验是经常碰到的问题．某些产品随着时间的推移，其可靠程...     

非线性系统的线性对称结构

非线性系统的线性对称结构洪奕光，程代展（中国科学院系统科学研究所，北京１０００８０）１９９１年１２月２０日收到．１９９３年９月１６日收到压缩稿，一、引言近年来，人们对非线性控制系统对称性问题的研究很感兴趣．这主要是因为现实世界存在着大量的对称现象，而...     

非线性波的指数衰减(I)

非线性波的指数衰减（Ｉ）盛其荣（新疆大学，乌鲁木齐市８３００４６）国家自然科学基金资助项目．１９９１年５月２２日收到，１９９１年１１月１１日收到修改稿．一、引言考虑下面问题：其中中的有界开集，边界且存在常数ｃ＞０使中的有界函数且在。内，（５）这里中非...     

半无穷向量最优化问题的最优性条件

半无穷向量最优化问题的最优性条件李泽民（重庆建筑大学，６３００４５）１９９０年８月２７日收到．１９９３年３月１日收到修改、压缩稿．无穷维空间中的向量极值问题已引起了不少学者的兴趣［２－４］．本文研究半无穷向量极值问题的最优性条件，得出了一系列有意义的...     

非线性跟踪─微分器

非线性跟踪一微分器韩京清，王伟（中国科学院系统科学研究所，北京１０００８０）国家自然科学基金资助课题．１９９２年７月２５日收到，１９９３年２月１７日收到修改稿．一、前言在实际工程问题中，常存在由不连续或带随机噪声的量测信号合理地提取连续信号及微分信号...     

带梯度项的半线性椭圆与抛物型方程解的死核问题

带梯度项的半线性椭圆与抛物型方程解的死核问题程尚斌（兰州大学数学系，兰州７３００００）兰州大学科研基金资助课题．１９９１年３月１１日收到，１９９１年１１月２３日收到修改压缩稿．一、引言１９８４年，人们发现对一定类型的半线性椭圆与抛物型方程，它们具非零...     

回归曲线的加权正交级数估计

回归曲线的加权正交级数估计杨瑛（北京大学概率统计系，北京１００８７１）国家自然科学基金资助项目．１９８９年１２月３日收到．１９９０年１１月２２日收到第一次修改稿．１９９２年８月７日收到第二次修改稿．一、引论自１９６２年Ｃｅｎｃｏｖ［１］提出了密度函数...     

The role of functional data analysis for instantaneous frequency estimation

This paper proposes a method for estimating the instantaneous frequency of a nonstationary signal; this method is based on a combination of empirical mode decomposition and functional data analysis. The proposed method incorporates a basis expansion technique for a functional data into time-varying phase derived by empirical mode decomposition and Hilbert transform, which provides a stable instantaneous frequency function. The superiority of the proposed method for instantaneous frequency estimation is demonstrated by various simulation studies. The analysis of multicomponent signals by the proposed method is also discussed. Furthermore, it is shown that the proposed method is highly effective for identifying groups (clusters) of nonstationary signals on the basis of the instantaneous frequency information.     

The numerical solution of the non-linear integro-differential equations based on the meshless method

This article investigates the numerical solution of the nonlinear integro-differential equations. The numerical scheme developed in the current paper is based on the moving least square method. The moving least square methodology is an effective technique for the approximation of an unknown function by using a set of disordered data. It consists of a local weighted least square fitting, valid on a small neighborhood of a point and only based on the information provided by its n closet points. Hence the method is a meshless method and does not need any background mesh or cell structures. The error analysis of the proposed method is provided. The validity and efficiency of the new method are demonstrated through several tests.     

一种基于矩阵初等变换的Schmidt正交化方法

对向量组的Schmidt正交化法和合同变换法的关系进行了分析,指出Schmidt正交化法就是合同变换法中利用规范化初等变换后的一种特殊情况,由此给出一种基于矩阵初等变换的Schmidt正交化方法——Schmidt初等变换正交化法,以及这一方法在软件Matlab上实现的程序.     

Numerical solution of the coupled viscous Burgers’ equation

In the present paper, a numerical method is proposed for the numerical solution of a coupled system of viscous Burgers’ equation with appropriate initial and boundary conditions, by using the cubic B-spline collocation scheme on the uniform mesh points. The scheme is based on Crank–Nicolson formulation for time integration and cubic B-spline functions for space integration. The method is shown to be unconditionally stable using von-Neumann method. The accuracy of the proposed method is demonstrated by applying it on three test problems. Computed results are depicted graphically and are compared with those already available in the literature. The obtained numerical solutions indicate that the method is reliable and yields results compatible with the exact solutions.     

Burgers方程的一类交替分组方法

对于Burgers方程给出了一组新的Saul'yev型非对称差分格式，并用这些差分格式构造了求解非线性Burgers方程的交替分组四点方法．该算法把剖分节点分成若干组，在每组上构造能够独立求解的差分方程．因此算法具有并行本性，能直接在并行计算机上使用．章还证明了所给算法线性绝对稳定．数值试验表明，该方法使用简便，稳定性好，有很好的精度。     

A Robin-Robin Domain Decomposition Method for a Stokes-Darcy Structure Interaction with a Locally Modified Mesh

A new numerical method based on locally modified Cartesian meshes is proposed for solving a coupled system of a fluid flow and a porous media flow. The fluid flow is modeled by the Stokes equations while the porous media flow is modeled by Darcy's law. The method is based on a Robin-Robin domain decomposition method with a Cartesian mesh with local modifications near the interface. Some computational examples are presented and discussed.     

A mixed collocation–finite difference method for 3D microscopic heat transport problems

Three-dimensional time-dependent initial-boundary value problems of a novel microscopic heat equation are solved by the mixed collocation–finite difference method in and on the boundaries of a particle when the thickness is much smaller than both the length and width. The collocation method on fixed grid size is used to approximate the space operator, whereas the finite difference scheme is used for time discretization. This new mixed method is applied to a novel heat problem in a particle, in order to compute the temperature distribution in and on the particle's surface. The second derivatives of the basis functions for the spectral approximation are derived. Direct substitution of derivatives in the model transforms the differential equation into a linear system of equations that is solved by the specific preconditioned conjugate gradient method. The high-order accuracy and resolution achieved by the proposed method allows one to obtain engineering-accuracy solution on coarse meshes. The consistency, stability and convergence analysis are provided and numerical results are presented.     

A nonasymptotic method for singular perturbation problems

In this paper, an approximate method for the numerical integration of singularly perturbed two-point boundary-value problems with a boundary layer on the left end of the underlying interval is presented. The method is distinguished by the following fact: the original second-order differential equation is replaced by an approximate first-order differential equation with a small deviating argument and is solved efficiently by employing the Simpson rule, coupled with the discrete invariant imbedding algorithm. The proposed method is iterative on the deviating argument. Several numerical examples have been solved to demonstrate the applicability of the method.     

The Laplace transform and polynomial Trefftz method for a class of time dependent PDEs

In this paper, we present a new method for solving 1D time dependent partial differential equations based on the Laplace transform (LT). As a result, the problem is converted into a stationary boundary value problem (BVP) which depends on the parameter of LT. The resulting BVP is solved by the polynomial Trefftz method (PTM), which can be regarded as a meshless method. In PTM, the source term is approximated by a truncated series of Chebyshev polynomials and the particular solution is obtained from a recursive procedure. Talbot’s method is employed for the numerical inversion of LT. The method is tested with the help of some numerical examples.     

Contaminant Transport with Adsorption in Dual-Well Flow

Numerical approximation schemes are discussed for the solution of contaminant transport with adsorption in dual-well flow. The method is based on time stepping and operator splitting for the transport with adsorption and diffusion. The nonlinear transport is solved by Godunov's method. The nonlinear diffusion is solved by a finite volume method and by Newton's type of linearization. The efficiency of the method is discussed.