共查询到20条相似文献,搜索用时 46 毫秒
1.
R^n上一类半线性椭圆方程妥的存在唯一性和渐近性质 总被引:5,自引:0,他引:5
用上下解方法和位势估计,研究了R^n上具有次线性项加超线性项半线性椭圆方程-Δu=a(x)Uu^a+λb(x)u^s,x∈R^n给出了其有界正解的存在性,唯一性和渐近性质,其中0〈α〈1,s〉1,为常数,λ〉0参数。‘ 相似文献
2.
给出了任意流场中颗粒运动方程的无因次和线性微分方程形式,估计了颗粒运动方程中的一些相关项,借助于一些数学推导和处理,求得了此线性颗粒运动方程的通解。 相似文献
3.
给出了任意流场中颗粒运动方程的无因次和线性微分方程形式.估计了颗粒运动方程中的一些相关项.借助于一些数学推导和处理,求得了比线性颗粒运动方程的通解. 相似文献
4.
Navier-Stokes方程流函数形式两重网格算法的误差分析 总被引:2,自引:2,他引:0
对定常Navier-Stokes方程流函数形式两重网格有限元算法进行了误差分析。此方法包括在粗网格上求解一个非线性问题,在细网格上求解一个线性问题,然后再在粗网格上求解一个线性校正问题。分析了包括校正项和不包括校正项两种方法的误差,得出对于任意固定的Beynolds数,能达到最优逼近阶。 相似文献
5.
对于线性对流占优扩散方程,采用特征线有限元方法离散时间导数项和对流项,用分片线性有限元离散空间扩散项,并给出了一致的后验误差估计,其中估计常数不依赖与扩散项系数。 相似文献
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本文揭示了一类超线性边值问题在环域上有无限多的正对称解,此结果对非线性项的增长性除超线性外无其它限制.本文主要方法是相关常微分方程解的能量分析和相平面分析. 相似文献
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有资格限制的指派问题的求解方法 总被引:3,自引:0,他引:3
在实际的指派工作中,常会遇到某个人有没有资格去承担某项工作的问题,因此,本建立了有资格限制的指派问题的数学模型。在此数学模型中,将效益矩阵转化为判定矩阵,由此给出了判定此种指派问题是否有解的方法;在有解的情况下,进一步将效益矩阵转化为求解矩阵,从而将有资格限制的指派问题化为传统的指派问题来求解。最后给出了一个数值例子来说明这样的处理方法是有效的。 相似文献
12.
完全偶图的星因子计数 总被引:2,自引:0,他引:2
图G的一个星因于是G的一个支撑子图,其中每一个分支是一个星图.本文研究完全偶图Km,n的星因子计数,给出了Km,x存在由K个分支构成的星因子的充要条件,进而给出了Km,n星因子计数的公式. 相似文献
13.
Arthur Cohen Harold B. Sackrowitz 《Annals of the Institute of Statistical Mathematics》1990,42(4):623-636
The problem of estimating the probability of unobserved outcomes or, as it is sometimes called, the conditional probability
of a new species, is studied. Good's estimator, which is essentially the same as Robbins' estimator, namely the number of
singleton species observed divided by the sample size, is studied from a decision theory point of view. The results obtained
are as follows: (1) When the total number of different species is assumed bounded by some known number, Good's and Robbins'
estimators are inadmissible for squared error loss. (2) If the number of different species can be infinite, Good's and Robbins'
estimators are admissible for squared error loss. (3) Whereas Robbins' estimator is a UMVUE for theunconditional probability of a new species obtained in one extra sample point, Robbins' estimator is not a uniformly minimum mean squared
error unbiased estimator of the conditional probability of a new species. This answers a question raised by Robbins. (4) It
is shown that for Robbins' model and squared error loss, there are admissible Bayes estimators which do not depend only on
a minimal sufficient statistic. A discussion of interpretations and significance of the results is offered.
Research supported by NSF Grant DMS-88-22622. 相似文献
14.
Jõgi Henna 《Annals of the Institute of Statistical Mathematics》1985,37(1):235-240
Summary Suppose thatH is a mixture of distributions for a given familyF A necessary and sufficient condition is obtained under whichH is, in fact, a finite mixture. An estimator of the number of distributions constituting the mixture is proposed assuming
that the mixture is finite and its asymptotic properties are investigated. 相似文献
15.
M. Giusti G. Lecerf B. Salvy J.-C. Yakoubsohn 《Foundations of Computational Mathematics》2005,5(3):257-311
At the beginning of the 1980s, M. Shub and S. Smale developed a
quantitative analysis of Newton's method for multivariate analytic
maps. In particular, their α-theory gives an effective
criterion that ensures safe convergence to a simple isolated zero.
This criterion requires only information concerning the map at the
initial point of the iteration. Generalizing this theory to multiple
zeros and clusters of zeros is still a challenging problem. In this
paper we focus on one complex variable function. We study general
criteria for detecting clusters and analyze the convergence of
Schroder's iteration to a cluster. In the case of a multiple root,
it is well known that this convergence is quadratic. In the case of a
cluster with positive diameter, the convergence is still quadratic
provided the iteration is stopped sufficiently early. We propose a
criterion for stopping this iteration at a distance from the cluster
which is of the order of its diameter. 相似文献
16.
首先在一般度量空间上给出有限积映射是Li-Yorke混沌的一个判据,并且用反倒展示:当有限积映射是Li-Yorke混沌时,未必一定存在因子映射是Li-Yorke混沌的.然后,利用上述判据,在[0,1]N上证明有限积映射有不可数scrsmbled集的一个充要条件.进而,推出关于有限积映射为Li-Yorke 混沌的一组等价... 相似文献
17.
自然数幂求和公式的计算机实现 总被引:5,自引:1,他引:4
自然数幂的求和问题 ,一直受到人们的关注 .著名数学家陈景润对此就有过较好的研究 ,更多结果散见其他许多文献 .但都比较烦琐 .本文借助 Mathematica软件 ,利用高阶等差数列的一个结论 :m阶等差数列的充要条件是其前 n项和为 n的 m+ 1次多项式 .给出了一种求自然数幂前 n项和的一种简单方法 .利用此方法还可实现小于 m的自然数幂前 n项和的同时实现 . 相似文献
18.
Thehomotopical rank of a mapf:M →N is, by definition, min{dimg(M) ¦g homotopic tof}. We give upper bounds for this invariant whenM is compact Kähler andN is a compact discrete quotient of a classical symmetric space, e.g., the space of positive definite matrices. In many cases the upper bound is sharp and is attained by geodesic immersions of locally hermitian symmetric spaces. An example is constructed (Section 9) to show that there do, in addition, exist harmonic maps of quite a different character. A byproduct is construction of an algebraic surface with large and interesting fundamental group. Finally, a criterion for lifting harmonic maps to holomorphic ones is given, as is a factorization theorem for representations of the fundamental group of a compact Kähler manifold. The technique for the main result is a combination of harmonic map theory, algebra, and combinatorics; it follows the path pioneered by Siu in his ridigity theorem and later extended by Sampson. 相似文献
19.
In dynamical systems examples are common in which two or more attractors coexist, and in such cases the basin boundary is nonempty and the basins often have fractal basin boundaries. The purpose of this paper is to describe the structure and properties of unbounded basins and their boundaries for two-dimensional diffeomorphisms. Frequently, if not always, there is a periodic saddle on the boundary that is accessible from the basin. Carathéodory and many others developed an approach in which an open set (in our case a basin) is compactified using so-called prime end theory. Under the prime end compactification of the basin, boundary points of the basin (prime ends) can be characterized as either type 1, 2, 3, or 4. In all well-known examples, most points are of type 1. Many two-dimensional basins have a basin cell, that is, a trapping region whose boundary consists of pieces of the stable and unstable manifolds of a well chosen periodic orbit. Then the basin consists of a central body (the basin cell) and a finite number of channels attached to it, and the basin boundary is fractal. We present a result that says {a basin has a basin cell} if and only if {every prime end that is defined by a chain of unbounded regions (in the basin) is a prime end of type 3 and furthermore all other prime ends are of type 1}. We also prove as a parameter is varied, the basin cell for a basin B is created (or destroyed) if and only if either there is a saddle node bifurcation or the basin B has a prime end that is defined by a chain of unbounded regions and is a prime end of either type 2 or type 4. 相似文献
20.
Benito Hernández-Bermejo 《Journal of Mathematical Analysis and Applications》2008,344(2):655-666
The determination of solutions of the Jacobi partial differential equations (PDEs) for finite-dimensional Poisson systems is considered. In particular, a novel procedure for the construction of solution families is developed. Such a procedure is based on the use of time reparametrizations preserving the existence of a Poisson structure. As a result, a method which is valid for arbitrary values of the dimension and the rank of the Poisson structure under consideration is obtained. In this article two main families of time reparametrizations of this kind are characterized. In addition, these results lead to a novel application which is also developed, namely the global and constructive determination of the Darboux canonical form for Poisson systems of arbitrary dimension and rank two, thus improving the local result provided by Darboux' theorem for such a case. 相似文献