求加权广义逆的矩阵方法

本文给出了应用矩阵方法求矩阵Ａ的加权广义逆Ａ＾［１，２，Ｗ３］，Ａ＾［１，２，ｗ３］和Ａ＾［１，２］［ｗ，ｗ］的充要条件。     

关于对Fuzzy弱自反关系证明的注记

陈贻源［１］和张文修［２］分别引入了Ｆｕｚｚｙ弱自反关系的定义和有关的证明。本文在［１］和［２］给出Ｆｕｚｚｙ弱自反关系定义的基础上，对［１］和［２］的有关Ｆｕｚｚｙ弱自反关系证明提出了异议，并给出了新的证明。     

L─Fuzzy拓扑空间中几种正则及关系

本文我们将介绍三种不同于文献［１］中的正则．分别记作［正则］１、［正则］２、［正则］３。并讨论它们之间以及与［１］中正则的关系，我们将证明［正则］２不仅拓宽了原正则［１］。而且还具有相应好的性质。同时还将证明［正则］３在可拓扑生成条件下与［１］中正则是等价的。     

关于二维合作自治系统的闭轨线

本文主要研究二维合作自治系统的闭轨线，推广了［１］的结果，得到了定理１于定理５。为简便计，本文采用［１］的术语，而未说明的概念或符号引自［２］。     

也谈费马─斯坦勒尔问题

也谈费马─斯坦勒尔问题刘凯年（重庆师范学院数学系６３００４７）文献［１］（见本刊１９９４年第３期）、［２］、［３］用不同方法解决了费马一斯坦勒尔问题．但［３］为实验解，未给出严格的数学证明，［１］、［２］的方法又比较繁难，且［１］的方法很难为中学生所...     

也谈对数大小的比较

也谈对数大小的比较万兴灿（湖北省宜昌市第一中学４４３０００）探究文［１］、［２］、［３］获益非浅，对比言之，文［３］方法从形式到实质仍是文［２］的方法．本文倾向文［１］处理方法，加以推广，则可较全面、简捷地解决对数大小的比较．定理１设１＜ａ＜ｂ，ｍ＞...     

数学问题解答

数学问题解答１９９７年１１月号问题解答（解答由问题提供人给出）１１０１设ａ，ｂ，ｃ，ｄ，ｅ是正整数，且ａ＜ｂ＜ｃ＜ｄ＜ｅ，［ｍ，ｎ］是ｍ与ｎ的最小公倍数．求：１［ａ，ｂ］＋１［ｂ，ｃ］＋１［ｃ，ｄ］＋１［ｄ，ｅ］的最大值．解设Ｓ＝１［ａ，ｂ］＋１［ｂ...     

积分算子的n-逼近数

本文研究了积分算子ＴＫ：Ｌｑ［０，１］→Ｌｑ［０，１］，（ｑ≥１）当核 Ｋ（ｓ， ｔ）是 Ｓｏｂｏｌｅｖ空间 Ｗｐｒ（［０， １］２）中元素时ｎ－逼近数 ａｎ（ＴＫ： Ｌｑ→ Ｌｑ）的估计，并把这个估计应用于退化核方法解第二类线性Ｆｒｅｄｈｏｌｍ方程（Ｉ一ＴＫ）ｘ＝ｙ时，Ｂａｄｈｖａｌｏｖ［５］意义下最佳误差的讨论中，所得到的最佳误差之估计当ｑ＝１时，最优化了［１０］的结论．     

两类求解刚性常微分方程的指数拟合法

本文提出了两类不需计算高阶全导数的３价和４价指数拟合的单步法，这些方法分别改进或推广了［１］－［４］中的某些方法，初步数值试验表明，这些方法用于求解某些ｓｔｉｆｆ问题，优于［１］－［４］中同阶方法。     

一类奇异积分在空间L［0，1］的收敛性

本文构造了一类奇异积分，并讨论了在空间Ｌ［０，１］的收敛性，它包含了和研究过的三个线性算子，并将前面两个算子的收效性由空间Ｃ［０，１］，推广到空间Ｌ［０，１］。     

THE l~1-STABILITY OF A HAMILTONIAN-PRESERVING SCHEME FOR THE LIOUVILLE EQUATION WITH DISCONTINUOUS POTENTIALS

We study the l^1-stability of a Haxniltonian-preserving scheme, developed in [Jin and Wen, Comm. Math. Sci., 3 （2005）, 285-315], for the Liouville equation with a discontinuous potential in one space dimension. We prove that, for suitable initial data, the scheme is stable in the l^1-norm under a hyperbolic CFL condition which is in consistent with the l^1-convergence results established in [Wen and Jin, SIAM J. Numer. Anal., 46 （2008）, 2688-2714] for the same scheme. The stability constant is shown to be independent of the computational time. We also provide a counter example to show that for other initial data, in particular, the measure-valued initial data, the numerical solution may become l^1-unstable.     

Stability of degenerate abelian varieties

We compactify canonically the moduli scheme of abelian schemes over Z[+_N,1/N] by introducing the noncommutative level structures. Any degenerate abelian scheme on the boundary of the compactification is a singular one among our models - projectively stable quasi-abelian schemes. We prove that a degenerate abelian scheme has Kempf-stable Hilbert points if and only if it is a projectively stable quasi-abelian scheme.     

An asymptotic preserving scheme with the maximum principle for the M1 model on distorded meshes

In this Note, we show that a recent scheme introduced by Buet et al. (2011) [5] for the nonlinear two moments $M_1$ model of linear transport and which captures correctly the diffusion limit on distorded meshes (AP scheme) also possesses the maximum principle. The main idea of the design of this scheme is to rewrite the model as a gas dynamics model and to use an Eulerian scheme, derived from a Lagrange + remap scheme. To obtain the AP property we use the multidimensional extension, developed by Buet et al. (2012) [6], of the Jin and Levermore (1996) procedure [9] for the hyperbolic heat equation. We will show that this scheme is entropic which ensures the maximum principle of the $M_1$ model. More we present some numerical results, on distorted quadrangular and triangular meshes which show that the scheme is second order in the diffusive regime.     

解含转向点问题的完全指数型拟合差分方法

本文对含转向点的微分方程边值问题建立了完全指数型拟合差分格式,证明了此格式具有一阶一致收敛性.推广了Miller[1]的方法,简化了证明过程.数值结果表明本格式比Il'in[2]格式要好.     

具弱色散误差的单调差分格式

本文基于[1]、[2]的理论分析,分别给出了计算(一维、二维)非线性双曲方程组的两类具弱色散误差的单调格式。§2针对一维气动力学方程组,通过数值结果。就激波的逼近问题,与已有的格式进行了比较。     

A Stabilized Low Order Finite Element Method for Three Dimensional Elasticity Problems

We introduce a low order finite element method for three dimensional elasticity problems. We extend Kouhia-Stenberg element [12] by using two nonconforming components and one conforming component, adding stabilizing terms to the associated bilinear form to ensure the discrete Korn's inequality. Using the second Strang's lemma, we show that our scheme has optimal convergence rates in $L^2$ and piecewise $H^1$-norms even when Poisson ratio $\nu$ approaches $1/2$. Even though some efforts have been made to design a low order method for three dimensional problems in [11,16], their method uses some higher degree basis functions. Our scheme is the first true low order method. We provide three numerical examples which support our analysis. We compute two examples having analytic solutions. We observe the optimal $L^2$ and $H^1$ errors for many different choices of Poisson ratios including the nearly incompressible cases. In the last example, we simulate the driven cavity problem. Our scheme shows non-locking phenomena for the driven cavity problems also.     

Time-adaptive multirate generalized-structure additively partitioned Runge-Kutta schemes for mechanical fluid-structure interaction

We extend the multirate GARK approach by Günther and Sandu [1, 2] to the case of non-constant micro steps per macro step to be able to cover time adaptivity, arriving at our so-called TAMGARK scheme and derive order conditions for arbitrary non-constant micro step sizes. The TAMGARK scheme is applied to the classical piston problem [3] to study the interaction between the piston and inviscid fluid flow in one spatial dimension. We demonstrate the functionality of the chosen time-adaptation strategy and the ability of the overall scheme to preserve the order of the basic schemes. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A numerical model for the Raman amplification for laser-plasma interaction

In this paper, we continue the study of the Raman amplification initiated in [M. Colin, T. Colin, On a quasi-linear Zakharov system describing laser-plasma interactions, Differential Integral Equations 17(3–4) (2004) 297–330]. We use a dispersive, quasi-linear system. The quasi-linear part is not hyperbolic and this difficulty is overcome using the dispersion. We give an asymptotic result on a reduced system. We then introduce a simple, robust and efficient numerical scheme on the whole system that takes into account the non-hyperbolicity of the quasi-linear part as well as the nonlinear saturation of the Raman growth. The scheme is validated thanks to the asymptotic result. Finally, we present 1-D and 2-D simulations.     

对流扩散方程的本质非振荡特征差分方法

本文把特征差分法[1]和本质非振荡插值[3]相结合,提出了对流扩散方程的本质非荡性征差分格式,避免了基于Lagrange插值特征差分格式在求解解具有大梯度问题时所产生的非物理振荡,并给出了格式的严格误差估计及数值算例。     

On the convergence of the SAOR method and the error bounds for its acceleration

Given a linear system with Hermitian positive definite coefficient matrix A, a splitting of Varga's type [1] is considered, and the corresponding generalised SAOR scheme is presented. We obtain the convergence theorem for the SAOR method and give the error bound for the A-norm of the error vector for the SAOR semi-iterative method, hence extending the SAOR theory.