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1.
胡成根  李刚 《运筹与管理》2010,19(3):116-123
文章研究了公司的系统风险、债务风险和经营风险与公司的多元化程度的相关性。本文的实证结果表明,公司的系统风险与公司的多元化程度是正相关的;公司的债务风险与公司的多元化程度是正相关的;公司的经营风险与公司的多元化程度是负相关的。随着公司多元化程度加深,公司的经营风险会变小,但是公司面临的宏观的资本市场的系统风险和企业自身的债务风险,会随着变大。  相似文献   

2.
本文研究包含有一根部份嵌入的(辶回)转轴的半空间的性质.不用知道一给定的嵌入的轴的扭转问题的精确解,这些性质能指出此半空间的位移或应力场的某些特点并且有时可以用来检查数值解.文中给出嵌入半空间的受扭的刚性圆柱的轴的表面上的正确的应力分布的检查的例子.  相似文献   

3.
(四)罗氏几何的光辉照亮了科学前进的道路我们来分析他的学说的哲学意义.住罗氏的时代,哲学中占统治地位的思想足康德的“不可知论”,按照这批人的说法,客观世界是存在的,但是不可知的,时间空间是人心的创造,是人心给经验安排的秩序,我们所确实知道的世界的规律性是人心按先天的原则所创造出来的,先天就是与经验无关的,  相似文献   

4.
一个方程的解可以看作两个函数的图象的交点的横坐标。反过来,方程的解又可以反映两个函数之间的某种关系,即它们的图象相交的情况。因此,可以利用函数的性质对方程的解,特别是直接求解很困难的某些超越方程的解的情况作出定性的讨论。也可以利用方程的解对函数的图象间的交点个数作出定量的研究,本文主要通过对函数y=x~(1/x)和y=x~x的性质的分析,就方程a~x=x和a~x=loga~x等的解的情况进行讨论。  相似文献   

5.
通过含单位元的交换环的实素理想构造出对应的模的实素子模,得到模的序存在的一个充要条件,并对模的所有序的支集的交集(文中称作"模的核心")作出一定的刻划,找到了判断模中的元素属于模的核心的充要条件.  相似文献   

6.
本文讨论平面图形绕平面内的直线旋转的旋转体体积与被旋转的平面图形的形心的关系.当被旋转的平面图形的内部与旋转轴没有交点时,得到了用被旋转的平面图形的面积以及被旋转的平面图形的形心到旋转轴的距离表示的旋转体体积公式.  相似文献   

7.
维数不同的相关量之间的微积分关系王金贵(北京电力高等专科学校100044)我们可能都留意过,圆的面积的导数等于圆的周长,即,球的体积的导数等于球的表面积,即.反过来,当然有圆的周长的积分等于圆的面积,即.球的表面积的积分等于球的体积,即.事实上,不仅...  相似文献   

8.
利用二次曲线的切线的定义,分别讨论过二次曲线上的一点的切线的求法及过二次曲线外的一点的切线的两种求法,并且得到了存在奇异点的二次曲线的具体类型.  相似文献   

9.
研究极小圈模对与二元域拟阵的特征.首先给出拟阵M的极小圈模对,模对的并的秩与相应的超平面的交的秩三者的等价关系.在两个极小圈不等的条件下,证明了满足极小圈消去公理的极小圈是唯一的并且极小圈模对的对称差包含在其中,结合极小圈的对称差的表示,证明了极小圈与基的差的绝对值大于等于2.后面两个证明都把原来的必要条件推广为充要条件.最后,用M上不相同的极小圈,极小圈模对,极小圈的对称差表示,M上不相等的超平面,超平面的并不等于E及满足的秩等式极简单地刻划了二元域拟阵M的特征.  相似文献   

10.
(四)罗氏几何的光辉照亮了科学前进的道路我们来分析他的学说的哲学意义.在罗氏的时代,哲学中占统治地位的思想是康德的"不可知论",按照这批人的说法,客观世界是存在的,但是不可知的,时间空间是人心的创造,是人心给经验安排的秩序,我们所确实知道的世界的规律性是人心按先天的原则所创造出来的,先天就是与经验无关的,这样,我们的空间观念就完全是人心的创造,  相似文献   

11.
Orthogonal polynomials satisfy a recurrence relation of order two defined by two sequences of coefficients. If we modify one of these recurrence coefficients at a certain order, we obtain the so-called perturbed orthogonal sequence. In this work, we analyse perturbed Chebyshev polynomials of second kind and we deal with the problem of finding the connection coefficients that allow us to write the perturbed sequence in terms of the original one and in terms of the canonical basis. From the connection coefficients obtained, we derive some results about zeros at the origin. The analysis is valid for arbitrary order of perturbation.  相似文献   

12.
Optimal control of nonlinear evolution inclusions   总被引:1,自引:0,他引:1  
In this paper, we study the optimal control of nonlinear evolution inclusions. First, we prove the existence of admissible trajectories and then we show that the set that they form is relatively sequentially compact and in certain cases sequentially compact in an appropriate function space. Then, with the help of a convexity hypothesis and using Cesari's approach, we solve a general Lagrange optimal control problem. After that, we drop the convexity hypothesis and pass to the relaxed system, for which we prove the existence of optimal controls, we show that it has a value equal to that of the original one, and also we prove that the original trajectories are dense in an appropriate topology to the relaxed ones. Finally, we present an example of a nonlinear parabolic optimal control that illustrates the applicability of our results.This research was supported by NSF Grant No. DMS-88-02688.  相似文献   

13.
Nonlinear fractional differential-algebraic equations often arise in simulating integrated circuits with superconductors. How to obtain the nonnegative solutions of the equations is an important scientific problem. As far as we known, the nonnegativity of solutions of the nonlinear fractional differential-algebraic equations is still not studied. In this article, we investigate the nonnegativity of solutions of the equations. Firstly, we discuss the existence of nonnegative solutions of the equations, and then we show that the nonnegative solution can be approached by a monotone waveform relaxation sequence provided the initial iteration is chosen properly. The choice of initial iteration is critical and we give a method of finding it. Finally, we present an example to illustrate the efficiency of our method.  相似文献   

14.
Suppose you have one unit of stock, currently worth 1, which you must sell before time T. The Optional Sampling Theorem tells us that whatever stopping time we choose to sell, the expected discounted value we get when we sell will be 1. Suppose however that we are able to see a units of time into the future, and base our stopping rule on that; we should be able to do better than expected value 1. But how much better can we do? And how would we exploit the additional information? The optimal solution to this problem will never be found, but in this paper we establish remarkably close bounds on the value of the problem, and we derive a fairly simple exercise rule that manages to extract most of the value of foresight.  相似文献   

15.
In this research, we develop and introduce a theoretical and mathematical forecasting framework of immigrant integration using immigrant density as a single driver. First, we introduce the integration concepts we aim at forecasting. Thereafter, we introduce a theoretical and mathematical model of the relationship between integration and immigrant density. Based on this model, we develop a methodological forecasting framework. We test the framework using immigrant integration data from Spain. We produce the forecasts, and conduct the proper evaluation of them. Finally, we conclude with a brief discussion of the wider implications of our results.  相似文献   

16.
本文研究含左正则lpp-断面的lpp-半群的结构.特别地,给出了合右理想左正则lpp-断面的lpp-半群的一个结构.另外,还把这个结构用于一些特殊情况。  相似文献   

17.
From the classical Voronoi algorithm, we derive an algorithm to classify quadratic positive definite forms by their minimal vectors; we define some new invariants for a class, for which several conjectures are proposed. Applying the algorithm to dimension 5 we obtain the table of the 136 classes in this dimension, we enumerate the 118 eutactic quintic forms, and we verify the Ash formula.

  相似文献   


18.
苏淳  刘杰  胡治水 《数学进展》2007,36(2):181-188
本文讨论完全区间树顶点数目Sx的大数律,所采用的方法不同于单边区间树.文章包括三部分内容:首先探讨完全区间树所得以定义的概率空间,弄清楚它的结构,为强大数律的研究奠定理论基础.接着,针对完全区间树上的Sx的矩母函数不易求得的情况,另辟蹊径,求得Sx的期望和方差.最后,给出Sx的强弱大数律.  相似文献   

19.
何树红 《数学研究》1999,32(1):1-13
本文通过引入一类Frechet空间,证明了一类与流体力学有关的非线性发展方程的弱解存在着整体吸引子.  相似文献   

20.
We recall L-shapes, which are minimal distance diagrams, related to weighted 2-Cayley digraphs, and we give the number and the relation between minimal distance diagrams related to the same digraph. On the other hand, we consider some classes of numerical semigroups useful in the study of curve singularity. Then, we associate L-shapes to each numerical 3-semigroup and we describe some main invariants of numerical 3-semigroups in terms of their associated L-shapes. Finally, we give a characterization of the parameters of the L-shapes associated with a numerical 3-semigroup in terms of its generators, and we use it to classify the numerical 3-semigroups of interest in curve singularity.  相似文献   

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