一类非线性对流占优抛物型方程组的特征交替方向有限元方法

对一类非线性对流占优抛物型方程组建立时间离散的Patch逼近特征交替方向有限元格式 ,并给出了最优阶的L2 和H1模误差估计 .     

三维热传导型半导体问题的交替方向特征有限元方法

提出交替方向特征有限元方法,对电场位势方程采用混合元格式,对电子,空穴浓度方程采用交替方向特征有限元格式,对温度方程提出交替方向格式.应用向量积计算及先验估计理论和技巧,得到最佳的L2误差估计.     

双相滞热传导方程的有限元分析

本文考虑一类具有广泛应用背景的双相滞热传导方程混合边界问题．建立了其有限元和交替方向有限元的两种数值逼近格式．利用微分方程的先验估计理论与技巧,作出了数值解的L^2—范数估计结果．基于一系列的误差估计,也研究了两种逼近格式数值的稳定性和收敛性。     

三维含弥散可压核废料污染问题的交替方向有限元方法

考虑到数值求解三维可压缩核废料污染问题计算量大,利用块有限元逼近技术提出了交替方向有限元格式,将三维问题化为一系列一维问题逐次求解,大大降低了计算量.由于考虑的模型问题为可压缩且同时包含分子扩散和弥散的一般情形,这为误差分析带来困难,本文采用对误差方程进行差商(dt)处理的技巧,证明了格式的最优H1-模误差估计.     

半导体问题的交替方向有限元方法

该文用交替方向有限元方法求解半导体问题的Energy Trans port (ET)模型。对模型中椭圆型的电子位势方程采用交替方向迭代法，对流占优扩散的电子浓度和空穴浓度方程采用特征交替方向有限元方法，热传导方程利用Patch逼近采用交替方向有限元方法求解。利用微分方程的先验估计理论和技巧，分别得到了椭圆型方程和抛物型方程的最优H+1和L+2误差估计。     

拟线性Sobolev方程的特征有限元格式的交替方向预处理迭代解及其分析

考虑数值求解具有对流项的高维拟线性Ｓｏｂｏｌｅｖ方程,构造了特征有限元格式,提出用交替方向预处理迭代法求特征有限元格式在每一时间步所产生的代数方程组的近似解,整个计算过程仅对一个可方向交替的预处理矩阵求逆一次,大大降低了计算量．证明了迭代解的最佳L^2模误差估计,并给出了算法的拟优工作量估计．     

裂缝孔隙介质中二相驱动问题的交替方向有限元方法及理论分析

考虑裂缝孔隙介质中二相驱动问题的数值方法及理论分析。对压力方程采用混合有限元方法,对裂缝和岩块系统上的饱和度方程采用交替方向有限元方法,证明了交替方向有限元格式具有最优Ｌ２模和Ｈ１模误差估计。     

Sobolev方程的一类各向异性非协调有限元逼近

在各向异性网格下,分别讨论了Sobolev方程在半离散和全离散格式下的一类非协调有限元逼近,得到了与传统有限元方法相同的误差估计和一些超逼近性质.同时在半离散格式下,通过构造具有各向异性特征的插值后处理算子得到了整体超收敛结果.     

非线性对流扩散问题的交替方向差分流线扩散法

1引言Peaceman,Douglas等人于1955年提出了差分格式的交替方向法。随后,Douglas,Dupont于1972年又提出了有限元格式的交替方向法[1]。其基本思想是:对两个或三个空间变量的二阶抛物型和双曲型问题,将交替方向法与Galerkin方法相结合,通过算子分裂技术,把高维问题转化为一系列低维问题,交替地沿各空间变量的方向求解。[2]、[3]和[4]给出了对更一般扩散问题(带对流项的抛物方程)的数值求解和误差分析。     

裂缝-孔隙介质中地下水污染问题的Galerkin交替方向有限元方法

考虑裂缝 孔隙介质中地下水污染问题均匀化模型的数值模拟．对压力方程采用混合元方法,对浓度方程采用Ｇａｌｅｒｋｉｎ交替方向有限元方法,对吸附浓度方程采用标准Ｇａｌｅｒｋｉｎ方法,证明了交替方向有限元格式具有最优犔２ 和犎１ 模误差估计．     

一個H.Hopf推測的證明

<正> 假設一個有限複合形K上的定向S~2叢在K~3上有截面,那末Hopf從他的第二阻礙公式獲得了一個叢不變量△~4()∈H~4(K).Hopf曾經猜測過這個叢不變量與叢的4維示性類有關.本文的目的在證明這個推測是對的,更明確言之,應有     

关于J.T.Lewis的一个定理

它是在这些结点上满足插值约束的逼近函数的集合.用K_1中的元素对f的逼近就是所谓带插值约束的逼近.J.T.Lewis给出了在L_1范数意义下这类逼近的一个特征定理.     

REGULARITY OF FREE BOUNDARIES OF TWO-PHASE PROBLEMS FOR FULLY NONLINEAR ELLIPTIC EQUATIONS OF SECOND ORDER. II. FLAT FREE BOUNDARIES ARE LIPSCHITZ

ABSTRACT

In this second paper, we continue our study on the regularity of free boundaries for some fully nonlinear elliptic equations. Our result is if the free boundary is trapped in a sufficiently narrow strip formed by two Lipschitz graphs, then it is also a Lipschitz graph. Combining with the results in Part 1 (see Ref. [Wang]), the free boundary is C ^1,α.     

RATES OF A.S.CONVERGENCE OF THE ESTIMATION OF ERROR VARIANCE IN LINEAR MODELS

Under appropriate conditions we obtain the best rates of a.s.convergence of estimates5_n~2 of error variance σ~2 and establish the law of iterated logarithm     

ON A THEOREM OF A.A. LYAPUNOV

Abstract

In this note we obtain some extensions and an approximation of the Lyapunov convexity theorem by means of the bilinear integration of a set-valued function. The integration is performed successively with respect to a non-atomic, a direct sum and a Darboux vector measure. The necessary counterexamples are provided.     

ON ONE CONJECTURE OF R. S. SINGH

In 1979 R. S. Singh(Ann. Statist, 1979, p. 890) made a conjecture concerning the convergence rate of EB estimates of the parameter θ in an one-dimensional continuous exponential distribution family, under the square loss function, the prior distribution family being confined to a bounded interval. The conjecture asserts that the rate cannot reach o(1/n) or even O(1/n). In this article, the weaker part of this conjecture(i. e. the o(1/n) part) is shown to be correct.     

ADIABATIC DECOMPOSITION OF THE -DETERMINANT OF THE DIRAC LAPLACIAN. I. THE CASE OF AN INVERTIBLE TANGENTIAL OPERATOR

ABSTRACT

We discuss the decomposition of the ζ-determinant of the square of the Dirac operator into the contributions coming from the different parts of the manifold. The result was announced in the Note Ref. [16]. The proof sketched in the Note was based on results of Brüning and Lesch (see Ref. [4]). In the meantime we have found another proof, more direct and elementary, and closer to the spirit of the original papers which initiated the study of the adiabatic decomposition of the spectral invariants (see Refs. [7] Douglas, R.G. and Wojciechowski, K.P. 1991. Adiabatic Limits of the η-Invariants. The Odd-dimensional Atiyah–Patodi–Singer Problem. Comm. Math. Phys., 142: 139–168. [Crossref], [Web of Science ®] , [Google Scholar] and [21] Singer, I.M. 1988. “The η-Invariant and the Index”. In Mathematical Aspects of String Theory Edited by: Yau, S.-T. pp. 239–258. Singapore: World Scientific Press.  [Google Scholar]). We discuss this proof in detail. We study the general case (non-invertible tangential operator) in forthcoming work (see Refs. [17] Park, J. and Wojciechowski, K.P. 2001. Scattering Theory and Adiabatic Decomposition of the ζ-Determinant of the Dirac Laplacian 01–02. IUPUI Preprint [Google Scholar] and [18] Park, J. and Wojciechowski, K.P. 2001. Adiabatic Decomposition of the ζ-Determinant of the Dirac Laplacian II. The Case of Non-invertible Tangential Operator In preparation [Google Scholar]). In the Appendix we present the computation of the cylinder contribution to the ζ-function of the Dirac Laplacian on a manifold with boundary, which we need in the main body of the paper. This computation is also used to show the vanishing result for the ζ-function on a manifold with boundary.     

一类二阶非线性常微分方程解的有界性

本文研究了下列微分方程解的有界性，其中关于ｔ是１－周期的而关于ｘ是拟周期的．     

A NOTE ON A PROBLEM OF BOAS R.P.

To answer the rest part of the problem of Boas R. P. on derivative of polynomial, it is shown that if $\[p(z)\]$ is a polynomial of degree n such that $\[\mathop {\max }\limits_{\left| z \right| \le 1} \left| {p(z)} \right| \le 1\]$ and $\[{p(z) \ne 0}\]$ in $\[\left| z \right| \le k,0 < k \le 1\]$, then $\[\left| {{p^''}(z)} \right| \le n/(1 + {k^n})\]$ for $\[\left| z \right| \le 1\]$. The above estimate is sharp and the equation holds for $\[p(z) = ({z^n} + {k^n})/(1 + {k^n})\]$.     

ON GROWTH OF MEROMORPHIC SOLUTIONS OF NONLINEAR DIFFERENCE EQUATIONS AND TWO CONJECTURES OF C.C. YANG

In this paper, we investigate the growth of the meromorphic solutions of the following nonlinear difference equationsf(z)n+ P_(n-1)(f) = 0,where n ≥ 2 and P_(n-1)(f) is a difference polynomial of degree at most n- 1 in f with small functions as coefficients. Moreover, we give two examples to show that one conjecture proposed by Yang and Laine [2] does not hold in general if the hyper-order of f(z) is no less than 1.