解抛物问题的一类新的瀑布型多重网格法

本文推广石钟兹 ,许学军对椭圆问题提出的新的瀑布型多重网格法到抛物问题 ,建立了相应的理论结果 .     

经济的瀑布型多重网格法(ECMG)

提出一种新的经济的瀑布型多重网格法(ECMG), 和通常的瀑布型多重网格法(CMG)的工作量相比, 新的瀑布型多重网格法在每层上的工作量 都相应的减少, 尤其是粗网格上的工作量将大量的减少. 新格式的误差和通常的 瀑布型多重网格法一样, 都具有最优精度. 最后给出数值算例 来验证所得理论的结果.     

半线性问题的瀑布型多重网格法

本文提出了求解半线性椭圆问题的一类新的瀑布型多重网格法，在网格层数固定的条件下证明了此法的最优阶收敛性。     

一类新的瀑布型多重网格法

对椭圆问题提出了一类新的瀑布型多重网格法.     

一类非线性椭圆问题的瀑布型多重网格法

本对二阶非线性椭圆问题提出一种瀑布型多重网格法，数值实验表明该算法非常有效，当d＝1时，给出了理论结果。     

一类非对称椭圆问题瀑布型多重网格法

本将瀑布型多重网格法用于求解非对称椭圆边值问题，数值结果表明算法是有效的。     

解二阶椭圆型变分不等式的瀑布型多重网格法

本文将瀑布型多重网格法推广应用于求解二阶椭圆型变分不等式并给出了一些数值例子。数值算例表明该算法是有效的。     

半线性椭圆型问题Mortar有限元逼近的瀑布型多重网格法

Mortar有限元法作为一个非协调的区域分解技术已得到许多研究者的关注(如文献[2]、[5]等)。本文对半线性椭圆型问题的Mortar有限元逼近提出了瀑布型多重网格法,并给出了此法的误差估计和计算复杂度估计定理。     

板问题多重网格法收敛性的低模估计

１．引言 近年来,多重网格法已成为行之有效的偏微分方程数值解法．对板问题有限元离散系统的多重网格法,也有不少的研究工作,如［４］,［５］,［１０］,［１３－１７］．在［４］,［１４－１７］中,作者讨论了Ｃ１协调元离散板问题的多重网格法,并在能量模（即 Ｈ２模）意义下获得了最优的收敛率．在［５］,［１０］中,作者讨论了非协调元离散问题的多重网格法,并在能量模意义下获得了最优的收敛率,同时在能量模意义下证明了套迭代多重网格法一阶收敛．但对板问题多重网格法的低模估计,即 Ｈ１模估计,至今尚未见研究,本文…     

论非线性多重网格法的逼近性质

多重网格法是一种求解椭圆边值问题离散所得的大型线性或非线性方程组的“最优”解法。在有限元离散情形,Hackbusch提出了一种多重网格法的收敛分析方法,即把线性或非线性的多重网格法收敛率的估计问题归结为所谓“光滑性质”与“逼近性质”的研究。在线性情形,若已知有限元解的误差估计,一般容易得到多重网格法的“逼近性质”。但对非线性多重网格法的“逼近性质”在什么条件下成立,尚未见到这方面的工     

Sybolical Index Calculation For Linear Circuits

The condition for the DAE index to be higher than one is calculated symbolically. Using Analog Insydes a function for the computer algera system Mathmatica is written. It calculates the index condition if the sparse tableau analysis method, or the modified nodal analysis method is applied.     

求解界面方程的Chebyshev加速算法

非重叠区域分解算法在于建立和求解相关的界面方程．建立界面方程在理论上虽。然容易推导，例如某些问题可用Gauss块消去法，但在实际计算时并不可行，所以界面方程在一些算法中是陷式的．而求解界面方程一般要进行预处理，本提出一种区域分解算法，可得出界面方程的显式表达．算法是完全并行的，所得出的界面方程的系数矩阵的条件数已与网参数无关，事实上就是(Sh^（1）)^-1Sh，进而可直接用收敛速度较快的Chebyshev加速算法求解该界面方程，在充分应用并行计算方法的条件下，本算法与[4]中的算法相比计算效率提高．     

符号几何规划的一种分解方法

针对符号几何规划提出了一种直接的分解方法,将难于求解的符号几何规划问题等价地转化为一个非线性程度很低的可分离规划,为寻求困难度高且规模较大的符号几何规划问题的求解提供了一种方法,特别是经此方法分解后的每个子问题均易于求解,最后给出了数值实例,验证了此方法的有效性．     

ALE-FEM For Two-Phase Flows With Insoluble Surfactants

We present a finite element method for the flow of two immiscible incompressible fluids in two and three dimensions. Thereby the presence of surface active agents (surfactants) on the interface is allowed, which alter the surface tension. The model consists of the incompressible Navier-Stokes equations for velocity and pressure and a convection-diffusion equation on the interface for the distribution of the surfactant. A moving grid technique is applied to track the interface, on that account a Arbitrary-Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equation is used. The surface tension force is incorporated directly by making use of the Laplace-Beltrami operator technique [1]. Furthermore, we use a finite element method for the convection-diffusion equation on the moving hypersurface. In order to get a high accurate method the interface, velocity, pressure, and the surfactant concentration are approximated by isoparametric finite elements. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

求解约束优化问题的记忆梯度Goldstein-Lavintin-Polyak投影算法

给求解无约束规划问题的记忆梯度算法中的参数一个特殊取法,得到目标函数的记忆梯度G o ldste in-L av in tin-Po lyak投影下降方向,从而对凸约束的非线性规划问题构造了一个记忆梯度G o ldste in-L av in tin-Po lyak投影算法,并在一维精确步长搜索和去掉迭代点列有界的条件下,分析了算法的全局收敛性,得到了一些较为深刻的收敛性结果.同时给出了结合FR,PR,HS共轭梯度算法的记忆梯度G o ldste in-L av in tin-Po lyak投影算法,从而将经典共轭梯度算法推广用于求解凸约束的非线性规划问题.数值例子表明新算法比梯度投影算法有效.     

On Majda' Model For Dynamic Combustion

Majda's model of dynamic combustion, consists of the system,

In this paper the Cauchy problem is considered. A weak entropy solution for this system is defined, existence, uniqueness and continuous dependence on initial data are proved, as well as finite propagation speed, for initial data in . The existence is proved via the "vanishing viscosity method". Furthermore it is proved that the solution to the Riemann problem converges as to the Z–N–D traveling wave solution. In the appendices, a second order numerical scheme for the model is described, and some numerical results are presented.     

简单图的一种计数方法

对某一类图的邻接矩阵进行分类 ,从而给出这类图的一种计数方法 ,并且这种方法比较原来的Polya方法更为可行 .     

Supercalm Multifunctions For Convergence Analysis

Calmness of multifunctions is a well-studied concept of generalized continuity in which single-valued selections from the image sets of the multifunction exhibit a restricted type of local Lipschitz continuity where the base point is fixed as one point of comparison. Generalized continuity properties of multifunctions like calmness can be applied to convergence analysis when the multifunction appropriately represents the iterates generated by some algorithm. Since it involves an essentially linear relationship between input and output, calmness gives essentially linear convergence results when it is applied directly to convergence analysis. We introduce a new continuity concept called ‘supercalmness’ where arbitrarily small calmness constants can be obtained near the base point, which leads to essentially superlinear convergence results. We also explore partial supercalmness and use a well-known generalized derivative to characterize both when a multifunction is supercalm and when it is partially supercalm. To illustrate the value of such characterizations, we explore in detail a new example of a general primal sequential quadratic programming method for nonlinear programming and obtain verifiable conditions to ensure convergence at a superlinear rate.     

A Scoring Criterion For Learning Chain Graphs

A chain graph allows both directed and undirected edges, and contains the underlying mathematical properties of the two. An important method of learning graphical models is to use scoring criteria to measure how well the graph structures fit the data. In this paper, we present a scoring criterion for learning chain graphs based on the Kullback Leibler distance. It is score equivalent, that is, equivalent chain graphs obtain the same score, so it can be used to perform model selection and model averaging.     

Numerical Projection Method For Inverse Fourier Transform And Its Application

Numerical projection method of the Fourier transform inversion from data given on a finite interval is proposed. It is based on an expansion of the solution into a series of eigenfunctions of the Fourier transform. The number of terms of the expansion depends on the length of the data interval. Convergence of the solution of the method is proved. The projection method for the case of the sine Fourier transform and the set of the odd Hermite functions being its eigenfunctions are examined and applied to numerical Fourier filtering.