一类求解分片延迟微分方程的线性多步法的散逸性

本文研究分片延迟微分方程本身及数值方法的散逸性问题．给出了一个关于此类问题本身散逸性的充分条件,同时得到了一类求解此类问题的线性多步法的数值散逸性结果,此结果表明所考虑的数值方法继承了方程本身的散逸性．数值试验进一步验证了理论结果的正确性．     

由分片线性谱序列来刻画函数空间L~p([0,1])(英文）

本文首先介绍一组指数函数序列,该序列元素的指数部分都是多节点分片线性的,而且该指数函数序列是函数空间L~2([0,1])的一组标准正交基底.运用古典的傅里叶级数的性质特征来证明该指数函数序列也能构成函数空间L~p([0,1])的基底,其中1p∞.同时也给出级数的部分和的几乎处处收敛性.     

关于“分片线性有限元最优L∞—误差估计”的注

关于二阶问题的分片线性有限元近似解的L~∞—误差估计,已有不少出色的工作,Nitsche,Scott,Frehse和Rannacher,Schatz和Wahlbin等分别利用不同的方法,证明了在u∈W~(2,∞)(Ω)的条件下,有‖u-u_h‖_(0,∞,Ω=0(h~2|lnh|)。这一误差估计与分片线性插值的逼近误差阶相比,并不是丰满(或最优)的。能否得到与插值逼近相同阶的L~∞—误差     

二阶拟线性双曲方程分片光滑行波的传播

本文对二阶拟线性严格双曲方程，得出了具有弱间断的分片光滑行波的传播和干扰的结果．为此还在最为一般的情形，证明了拟线性Ｃａｕｃｈｙ问题局部解的存在性与唯一性．     

一类线性混合模型的谱分解估计

谱分解估计(SDE)是新近提出的关于线性混合模型参数的一种新的估计方法,此方法的一个突出特点是同时给出固定效应参数和方差分量的显式解估计．本文就含两个方差分量的线性混合模型,对谱分解估计的性质做了进一步的研究,获得了方差分量的SDE和方差分析估计相等的充分必要条件,证明了在一定的条件下方差分量的SDE为一致最小方差无偏估计．     

一类4维3元线性码的重量谱

GF(q)上[n,k;q]线性码C的重量谱为序列(d1,d2,…dk),其中dr是C的r维子码的最小支持重量.文章利用有限射影几何方法确定了一类4维3元线性码的重量谱,并对其进行了验证.     

一类P元序列集的相关性和线性复杂度的分析

对于素数P和偶数n=2k,构造了一类周期为P^n-1的P”条序列组成的P元序列集s（r）,这里P^k≠2（rood3）,r与P^k=1互素．利用d-齐次函数的性质,确定了这类序列集的相关函数取-1±P^k-1,-1＋2·p^k四值及相应分布;使用推广的Key方法证明了这类序列集具有较大的线性复杂度下界．这类序列集可适用于CDMA通信系统和密码系统中．     

一类ρ元序列集的相关性和线性复杂度的分析

对于素数p和偶数n=2k,构造了一类周期为pn-1的pn条序列组成的p元序列集S(r),这里pk≠2(mod3),r与pk-1互素.利用d-齐次函数的性质,确定了这类序列集的相关函数取-1±pk,-1,-1+2.pk四值及相应分布;使用推广的Key方法证明了这类序列集具有较大的线性复杂度下界.这类序列集可适用于CDMA通信系统和密码系统中.     

关于一类无限维线性算子谱的刻画

利用有限维线性空间的理论,研究了一类无限阶Toeplitz矩阵的特征值问题,得到这类无限阶矩阵的特征值是连续变化的,并且其谱集合是由复平面上的单位圆盘{z∈C,|z|<1}被多项式函数f(z)=(?)a_iz~i作用后,所得到的像曲线内部的点组成.     

May谱序列的一些注记

令 p>5 是素数, A 表示模 p Steenrod代数, S 表示球谱的 p 局部化. 首先给出了有关May谱序列的一些重要定理, 然后作为应用, 利用May谱序列和Adams谱序列发觉了一族新的非零的球面稳定元素. 该新元素族次数为2(p-1)(pⁿ+sp²+sp+s)-7,在Adams谱序列中由 b_n-1g0γ_s∈ Ext_A^s+4,﹡( Z_pZ_p)所表示, 其中n≥4, 3≤s

     

Lp Convergence of Generalized Fourier Series Deduced by Piecewise Linear Spectral Sequences

In the present paper, we discuss some properties of piecewise linear spectral sequences introduced by Liu and Xu. We have a study on the pointwise and almost everywhere convergence of its corresponding series. Also, it is shown that the set G constructed from piecewise linear spectral sequences are bases, but not unconditional bases, for LP（0, 1） where 1 〈 p 〈 ∞, p ≠2.     

分片线性谱序列生成的广义Fourier级数的Lp收敛性

In the present paper, we discuss some properties of piecewise linear spectral sequences introduced by Liu and Xu. We have a study on the pointwise and almost everywhere convergence of its corresponding series. Also, it is shown that the set (G) constructed from piecewise linear spectral sequences are bases, but not unconditional bases, for LP(0,1) where 1 ＜ p ＜∞, p ≠ 2.     

Weakly Periodic Sequences of Bounded Linear Transformations: a Spectral Characterization

Let X and Y be two Hilbert spaces, and the space of bounded linear transformations from X into Y. Let {A } be a weakly periodic sequence of period T. Spectral theory of weakly periodic sequences in a Hilbert space is studied by H. L. Hurd and V. Mandrekar (1991). In this work we proceed further to characterize {A _n} by a positive measure and a number T of -valued functions a ₀, . . . ,a _T–1; in the spectral form , where and is an -valued Borel set function on [0, 2) such that      

On Quasi-Periodic Solutions of Differential Equations with Piecewise Constant Argument

We study the existence of quasi-periodic solutions to differential equations with piecewise constant argument (EPCA, for short). It is shown that EPCA with periodic perturbations possess a quasi-periodic solution and no periodic solution. The appearance of quasi-periodic rather than periodic solutions is due to the piecewise constant argument. This new phenomenon illustrates a crucial difference between ODE and EPCA. The results are extended to nonlinear equations.     

A Piecewise Linear Dual Phase-1 Algorithm for the Simplex Method

A dual phase-1 algorithm for the simplex method that handles all types of variables is presented. In each iteration it maximizes a piecewise linear function of dual infeasibilities in order to make the largest possible step towards dual feasibility with a selected outgoing variable. The algorithm can be viewed as a generalization of traditional phase-1 procedures. It is based on the multiple use of the expensively computed pivot row. By small amount of extra work per iteration, the progress it can make is equivalent to many iterations of the traditional method. While this is its most important feature, it possesses some additional favorable properties, namely, it can be efficient in coping with degeneracy and numerical difficulties. Both theoretical and computational issues are addressed. Some computational experience is also reported which shows that the potentials of the method can materialize on real world problems.     

Global Behavior of Rational Sequences Involving Piecewise Power Function

In this paper, we are concerned with the global behavior ofthe solutions of the difference equation

Spectral Sequences on Combinatorial Simplicial Complexes

The goal of this paper is twofold. First, we give an elementary introduction to the usage of spectral sequences in the combinatorial setting. Second we list a number of applications.In the first group of applications the simplicial complex is the nerve of a poset; we consider general posets and lattices, as well as partition-type posets. Our last application is of a different nature: the -quotient of the complex of directed forests is a simplicial complex whose cell structure is defined combinatorially.     

Piecewise Linear Interpolation With Nonequidistant Nodes

Pointwise and norm estimates for approximation of continuous function by piecewise linear interpolant with nonequidistant nodes are proved. Special attention is paid to the value of the absolute constants in front of the modulus.     

分段线性插值收敛速度的一种估计

给出了分段线性插值收敛速度的一种估计.     

Piecewise Linear Time Series Estimation with GRASP

This paper describes a heuristic to build piecewise linear statistical models with multivariate thresholds, based on a Greedy Randomized Adaptive Search Procedure (GRASP). GRASP is an iterative randomized sampling technique that has been shown to quickly produce good quality solutions for a wide variety of optimization problems. In this paper we describe a GRASP to sequentially split an n-dimensional space in order to build a piecewise linear time series model.