二维非饱和水流的全离散广义差分格式分析及其数值模拟

建立二维非饱和水流问题的全离散广义差分格式,讨论了全离散广义差分解的存在唯一性,并给出最优误差估计的证明．最后给出数值算例,验证方法的有效性.     

用非标准离散函数和差商定义新广义函数

在非标准分析框架下，用离散函数定义新广义函数，用差商定义其导数．对Schwartz广义函数以及更广的Gevrey超广义函数，文章证明了广义导数可以用差商表示．此外还给出了此新广义函数和Sobolev理论的关系．     

Implicit Difference Schemes for the Generalized Non-Linear Schrödinger System

In this paper we prove under certain weak conditions that two classes of implicit difference schemes for the generalized non-linear schrödinger system are convergent and that an iteration method for the corresponding non-linear difference equation is convergent. Therefore, quite a complete theoretical foundation of implicit schemes for the generalized non-linear Schrödinger system is established in this paper.     

Solving parabolic and hyperbolic equations by the generalized finite difference method

Classical finite difference schemes are in wide use today for approximately solving partial differential equations of mathematical physics. An evolution of the method of finite differences has been the development of generalized finite difference (GFD) method, that can be applied to irregular grids of points.     

广义差集与几乎完美序列

提出了广义差集的概念,并且给出了广义差集的一些初等性质.从应用的角度讲,广义差集就是使得其±1特征序列的自相关函数是(最多)三值的一种组合结构.因此,广义差集不仅仅是在概念(理论)上的推广,它还具有深层次的应用背景.事实上,给出了一些广义差集,它不是可分差集,也不是相对差集.同时也给出了一类广义差集存在的一些必要条件,使得这些广义差集对应的±1特征序列成为几乎完美序列.并举例说明本文中的方法是有效的.     

Finite Difference/Collocation Method for Two-Dimensional Sub-Diffusion Equation with Generalized Time Fractional Derivative

In this paper, we propose a finite difference/collocation method for two-dimensional time fractional diffusion equation with generalized fractional operator. The main purpose of this paper is to design a high order numerical scheme for the new generalized time fractional diffusion equation. First, a finite difference approximation formula is derived for the generalized time fractional derivative, which is verified with order $2-\alpha$ $(0<\alpha<1)$. Then, collocation method is introduced for the two-dimensional space approximation. Unconditional stability of the scheme is proved. To make the method more efficient, the alternating direction implicit method is introduced to reduce the computational cost. At last, numerical experiments are carried out to verify the effectiveness of the scheme.     

Conservative finite difference schemes for the generalized Zakharov–Kuznetsov equations

This paper is concerned with the construction of conservative finite difference schemes by means of discrete variational method for the generalized Zakharov–Kuznetsov equations and the numerical solvability of the two-dimensional nonlinear wave equations. A finite difference scheme is proposed such that mass and energy conservation laws associated with the generalized Zakharov–Kuznetsov equations hold. Our arguments are based on the procedure that D. Furihata has recently developed for real-valued nonlinear partial differential equations. Numerical results are given to confirm the accuracy as well as validity of the numerical solutions and then exhibit remarkable nonlinear phenomena of the interaction and behavior of pulse wave solutions.     

Determination of periodic orbits of nonlinear oscillators by means of piecewise-linearization methods

An approximate method based on piecewise linearization is developed for the determination of periodic orbits of nonlinear oscillators. The method is based on Taylor series expansions, provides piecewise analytical solutions in three-point intervals which are continuous everywhere and explicit three-point difference equations which are P-stable and have an infinite interval of periodicity. It is shown that the method presented here reduces to the well-known Störmer technique, is second-order accurate, and yields, upon applying Taylor series expansion and a Padé approximation, another P-stable technique whenever the Jacobian is different from zero. The method is generalized for single degree-of-freedom problems that contain the velocity, and (approximate) analytical solutions are presented. Finally, by introducing the inverse of a vector and the vector product and quotient, and using Taylor series expansions and a Padé approximation, the method has been generalized to multiple degree-of-freedom problems and results in explicit three-point finite difference equations which only involve vector multiplications.     

Endpoint theory for set-valued nonlinear asymptotic contractions with respect to generalized pseudodistances in uniform spaces

In uniform spaces, inspired by ideas of Banach, Tarafdar and Yuan, we introduce the concepts of generalized pseudodistances and generalized gauge maps, for set-valued dynamic systems we define various nonlinear asymptotic contractions and contractions with respect to these pseudodistances and gauges, provide conditions on the iterates of these set-valued dynamic systems and present a method which is useful for establishing conditions guaranteeing the existence and uniqueness of endpoints (stationary points) of these set-valued dynamic systems and conditions that each generalized sequence of iterations (in particular, each dynamic process) converges and the limit of a generalized sequence of iterations is an endpoint. The definitions, the results and the method are new for set-valued dynamic systems in uniform, locally convex and metric spaces and even for single-valued maps. The paper includes a number of various examples which show a fundamental difference between our results and those existing in the literature.     

Generalized isochronous centers for complex systems

In this paper, the definition of generalized isochronous center is given in order to study unitedly real isochronous center and linearizability of polynomial differential systems. An algorithm to compute generalized period constants is obtained, which is a good method to find the necessary conditions of generalized isochronous center for any rational resonance ratio. Its two linear recursive formulas are symbolic and easy to realize with computer algebraic system. The function of time-angle difference is introduced to prove the sufficient conditions. As the application, a class of real cubic Kolmogorov system is investigated and the generalized isochronous center conditions of the origin are obtained.     

Difference of two sets and estimation of clarke generalized Jacobian via quasidifferential

The notion of difference for two convex compact sets inR ⁿ , proposed by Rubinovet al, is generalized toR ^m×n . A formula of the difference for the two sets, which are convex hulls of a finite number of points, is developed. In the light of this difference, the relation between Clarke generalized Jacobian and quasidifferential, in the sense of Demyanov and Rubinov, for a nonsnooth function, is established. Based on the relation, the method of estimating Clarke generalized Jacobian via quasidifferential for a certain class of functions, is presented.     

Convergence on Finite Difference Solution for Semilinear Wave Equation in One Space Variable

61.IntroductionThesemilinearwaveequationareoftenappearinthestudyofphysical,chemical,mechani-cal,biologicalandotherproblems,onespecialexampleisthewell-knownKlein-Gordonequa-tlonutt-u..=f(u)(l)whichtakesanimportantrolesinthestudyofSoliton.Choicedifferentnonlineartermf,thevariousstandardequations['jaregotsuchastakingf(u)=sin(u),then(l)asaSine-Gordonequationandtakingf(u)=u-u3lthen(1)asagi-Wequationwhichisanimportantmodell.insolidphysicsandhighenergyphysics['j.Moreover,takingf(u)=f[sin(u) isin(7)…     

区间值合作对策的广义区间Shapley值

研究区间Shapley值通常对区间值合作对策的特征函数有较多约束,本文研究没有这些约束条件的区间值合作对策,以拓展区间Shapley值的适用范围。首先,本文指出广义H-差在减法与加法运算中存在的问题,进而提出了一种改进的广义H-差,称为扩展的广义H-差。然后,基于扩展的广义H-差,定义了区间值合作对策的广义区间Shapley值,并用区间有效性、区间对称性、区间哑元性和区间可加性等四条公理刻画了该广义区间Shapley值。同时,证明了该值的存在性与唯一性,而且得到了该值的一些性质。研究表明,任意的区间值合作对策的广义区间Shapley值都存在。最后,以算例说明该广义区间Shapley值的可行性与实用性。     

A reduction technique for discrete generalized algebraic and difference Riccati equations

This paper proposes a reduction technique for the generalized Riccati difference equation arising in optimal control and optimal filtering. This technique relies on a study on the generalized discrete algebraic Riccati equation. In particular, an analysis on the eigenstructure of the corresponding extended symplectic pencil enables to identify a subspace in which all the solutions of the generalized discrete algebraic Riccati equation are coincident. This subspace is the key to derive a decomposition technique for the generalized Riccati difference equation. This decomposition isolates a “nilpotent” part, which converges to a steady-state solution in a finite number of steps, from another part that can be computed by iterating a reduced-order generalized Riccati difference equation.     

Approximate Newton Methods for Nonsmooth Equations

We develop general approximate Newton methods for solving Lipschitz continuous equations by replacing the iteration matrix with a consistently approximated Jacobian, thereby reducing the computation in the generalized Newton method. Locally superlinear convergence results are presented under moderate assumptions. To construct a consistently approximated Jacobian, we introduce two main methods: the classic difference approximation method and the -generalized Jacobian method. The former can be applied to problems with specific structures, while the latter is expected to work well for general problems. Numerical tests show that the two methods are efficient. Finally, a norm-reducing technique for the global convergence of the generalized Newton method is briefly discussed.     

Predicting stochastic characteristics of generalized eigenvalues via a novel sensitivity-based probability density evolution method

This paper proposes a novel numerical method for predicting the probability density function of generalized eigenvalues in the mechanical vibration system with consideration of uncertainties in structural parameters. The eigenproblem of structural vibration is presented by first and the sensitivity of generalized eigenvalues with respect to structural parameters can be derived. The probability density evolution method is then developed to capture the probability density function of generalized eigenvalues considering uncertain material properties. Within the proposed method, the probability density evolution equation for the generalized eigenvalue problem is established accounting for the sensitivity of generalized eigenvalues with respect to structural parameters. A new variable which connects generalized eigenvalues to structural parameters is then introduced to simplify the original probability density evolution equation. Next, the simplified probability density evolution equation is solved by using the finite difference method with total variation diminishing schemes. Finally, the probability density function as well as the second-order statistical quantities of generalized eigenvalues can be predicted. Numerical examples demonstrate that the proposed method yields results consistent with Monte-Carlo simulation method within significantly less computation time and the coefficients of variation of uncertain parameters as well as the total number of them have remarkable effects on stochastic characteristics of generalized eigenvalues.     

Balanced generalized handcuffed designs

The definition of balanced generalized handcuffed designs (BHD) is of course more specific than that of the generalized handcuffed designs that we introduced in 1987.

In the first part of this paper, we present a particular property of a BHD, which is not necessarily that of a generalized handcuffed design.

Then, we provide the reader with a general procedure that enables one to obtain such designs, and is called a ‘difference method’. We also show how this difference method can be made more useful in the case where the set V on which a BHD is constructed is the residue classes of integers mod V.

The third part of this paper deals with the problem of the existence of a BHD; and a solution is given for a particular case. We assume that the method applied for solving this problem will allow for the constructing of many more theorems analogous to Theorem 3.     

抛物方程的一种广义差分法(有限体积法)

广义差分法自1982年被提出,至今已获得很大发展（见[1]或[10],这种方法在国际上被称为有限体积（元）法（见[8],[9]）,它的主要优点是保持物理量的局部守恒性.文[3],[5]分别将三角形网格上的椭圆型方程的广义差分法（有限体积法）（见[2],[4]）推广到抛物型方程.我们知道三角形网格与四边形网格是两种基本的分割空间区域的方法,实践上使用哪一种网格,要根据空间区域的几何形状而定.文[7],[6]讨论了一般四边形网上椭圆型方程的广义差分法.本文以抛物方程为模型,取试探函数空间为一般四边形剖分上的等参双线性元,检验函数空间为对偶剖分上的分片常数,导出了一种新的有效的广义差分算法（有限体积算法）,证明了半离散与全离散格式的最佳H1误差估计.遇到的主要困难是双线性形式a（uh,Πh＊uh）     

Attractors and Dimensions for Discretizations of a Generalized Ginzburg-Landau Equation

In this paper, we discretize the generalized Ginzburg-Landau equations with the periodic boundary condition by the finite difference method in spatial direction. It is proved that for each mesh size, there exist at tractors for the discretized systems. The bounds for the Hausdorff dimensions of the discrete attractors are obtained, and the various bounds are independtmt of tho mesh sizes.     

High order parameter-robust numerical method for singularly perturbed reaction-diffusion problems

We present a high order parameter-robust finite difference method for singularly perturbed reaction-diffusion problems. The problem is discretized using a suitable combination of fourth order compact difference scheme and central difference scheme on generalized Shishkin mesh. The convergence analysis is given and the method is proved to be almost fourth order uniformly convergent in maximum norm with respect to singular perturbation parameter ε. Numerical experiments are conducted to demonstrate the theoretical results.