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1.
黄建华  路钢 《数学杂志》2002,22(3):354-358
本文用有限差分格式对FitzHugh-Nagumo方程的时间变量和空间变量同时离散,给出了离散模型整体吸引子存在的条件。  相似文献   

2.
本文对一类非线性时间序列模型xt=φ(xt-1,…,xt-p)+εth(xt-1,…,xt-p)给出了高阶矩的存在条件。  相似文献   

3.
本文研究具弱衰减、小初值初始条件的一维Dirac-Klein-Gordon方程组解的存在时间估计问题,结果表明这类问题解的存在时间几乎比e-4大初值的弱衰减条件使得通常的方法不能使用,在此,通过利用Delort曾用过的方程组特征的曲率性质以及2次微局部椭圆正则性解决了该问题.  相似文献   

4.
分别研究了有限时间和无限时间情形下的一类奇异随机Markov跳变系统的N人微分博弈问题.利用配方法,得到了有限时间N人博弈的Nash均衡策略的微分Riccati方程,证明了Nash均衡策略的存在条件等价于微分Riccati方程存在解;无限时间内,N人博弈的Nash均衡策略的存在条件等价于代数Riccati方程存在解,并分别给出了均衡策略的显式表达及最优性能泛函值.最后,将所得的结果应用于现代鲁棒控制中的随机H_2/H_∞控制问题,得到了鲁棒控制策略的存在条件及显式表达.  相似文献   

5.
本文研究非稳态反应扩散对流方程ut=△u-f(u,Du)的死核问题,给出了一些死核存在的充分条件、死核形成时间的估计和死核大小的估计.  相似文献   

6.
该文研究了非线性边界条件下高维空间上更一般化的非线性抛物问题解的爆破现象以及全局解的存在性.通过构造辅助函数,并对方程中的已知数据项进行一些必要的假设,应用微分不等式技术,当爆破发生时推导了爆破时间的下界.也推到了方程的解一定发生的条件并得到了爆破时间的上界.同时,不管方程对外施力还是受到外力的作用,也研究了方程的解全局存在的条件.  相似文献   

7.
本文讨论了一类广义非自治离散松驰系统的时间最优控制问题,将R^n中点曲线的目标约束推广为凸集值函数的超曲线约束.在证明了松驰系统与原系统可达集相等的基础上,得到了最优控制的存在性.由凸集分离定理及终端时间闺值函数方程,我们获得了最大值原理及最优控制时间的确定方法.较之Hamilton方法,本文的条件更一般.离散松驰系统的相关结论可以用于分散控制.  相似文献   

8.
平稳性是研究时间序列的重要条件,本讨论一个扰动项为非对称稳定幂GARCH过程的模型的严平稳性与解的唯一性,并给出严平稳性与解存在的充要条件。  相似文献   

9.
非自治Lotka-Volterra扩散模型的持续生存与周期轨道(英)   总被引:5,自引:0,他引:5  
本文研究了一类非自治的捕食者一食饵扩散模型;其中食饵能在环境相异的两个缀块间有限制地扩散,但对捕食者来说,缀块间的扩散不受任何限制;另外假设模型的系数都是时间的函数.我们证明了在适当的条件下,这个系统能够持续生存,进一步给出了系统存在唯一全局渐近稳定正周期轨道的充分条件.  相似文献   

10.
一个可修系统的最优更换模型   总被引:14,自引:0,他引:14  
张元林  贾积身 《应用数学》1996,9(2):180-184
本文考虑了单部件、一个修理工组成的可修系统,在故障系统不能“修复如新”的前提下,我们利用几何过程,以系统年龄T为策略,选择最优的T使得系统经长期运行单位时间的期望效益达到最大.本文还在一定的条件下证明了最优更换策略T的唯一存在,且求出了系统经长期运行单位时间的最大期望效益的明显表达式.  相似文献   

11.
12.
张丽娜  吴建华 《数学进展》2008,37(1):115-117
One of the most fundamental problems in theoretical biology is to explain the mechanisms by which patterns and forms are created in the'living world. In his seminal paper "The Chemical Basis of Morphogenesis", Turing showed that a system of coupled reaction-diffusion equations can be used to describe patterns and forms in biological systems. However, the first experimental evidence to the Turing patterns was observed by De Kepper and her associates(1990) on the CIMA reaction in an open unstirred reactor, almost 40 years after Turing's prediction. Lengyel and Epstein characterized this famous experiment using a system of reaction-diffusion equations. The Lengyel-Epstein model is in the form as follows  相似文献   

13.
As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years (2001-2005). The main topics are: convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.  相似文献   

14.
In this paper, we study the explicit representation and convergence of (0, 1; 0)-interpolation on infinite interval, which means to determine a polynomial of degree ≤ 3n - 2 when the function values are prescribed at two set of points namely the zeros of Hn(x) and H′n(x) and the first derivatives at the zeros of H′n(x).  相似文献   

15.
Schr(o)dinger operator is a central subject in the mathematical study of quantum mechanics.Consider the Schrodinger operator H = -△ V on R, where △ = d2/dx2 and the potential function V is real valued. In Fourier analysis, it is well-known that a square integrable function admits an expansion with exponentials as eigenfunctions of -△. A natural conjecture is that an L2 function admits a similar expansion in terms of "eigenfunctions" of H, a perturbation of the Laplacian (see [7], Ch. Ⅺ and the notes), under certain condition on V.  相似文献   

16.
正Guest Editors:Hong Chen,Shanghai Jiao Tong University,Shanghai,China Guohua Wan,Shanghai Jiao Tong University,Shanghai,China David Yao,Columbia University,New York,USA Scope:Healthcare delivery worldwide has been fraught with high cost,low efficiency and poor quality of patient care service.For the field of operations research(OR),healthcare offers some of the biggest challenges as well as best opportunities in  相似文献   

17.
18.
In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p(R^n) into the Lebesgue space L^p with p 〈 1.  相似文献   

19.
In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.  相似文献   

20.
Due to the resolution of current laser technology, the accuracy of corneal topography as measured by the videokeratoscope is no longer adequate to provide precise enough data for refractive surgery or for the fitting of customized contact lenses. We present an algorithm for recovering corneal topography that makes use of modern differential geometric techniques and numerical descent in Sobolev spaces. We believe this algorithm may be used with the photo- and videokeratoscope to increase the accuracy of the recovered corneal topography.  相似文献   

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