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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.
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   

6.
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   

7.
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   

8.
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   

9.
科学计算用数字电子计算机的若干问题   总被引:1,自引:0,他引:1  
周毓麟 《数学进展》1989,18(4):433-438
数字电子计算机的发明与发展的主要动力是大型科学计算.计算机是应科学计算的需要而发明的,应科学计算的不断追求而迅速发展的.科学计算课题的要求是无限的,而计算机的解题能力是有限的,装备计算机的技术也是有限的.因此如何处处“节约”技术,最“经济”地使用技术,以当前有限的技术研制出计算能力尽可能大的计算机是科学计算工作者很关心的问题.  相似文献   

10.
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   

11.
We will show that some of the superconvergence properties for the mixed finite element method for elliptic problems are preserved in the mixed semi-discretizations for a diffusion equation and for a Maxwell equation in two space dimensions. With the help of mixed elliptic projection we will present estimates global and pointwise in time. The results for the Maxwell equations form an extension of existing results. For both problems, our results imply that post-processing and a posteriori error estimation for the error in the space discretization can be performed in the same way as for the underlying elliptic problem.  相似文献   

12.
Arleta Rasmußen 《Optimization》2017,66(12):2107-2124
In the experiment we model all possible consequences from misreporting for both the shareholder and for the manager, since we are interested in patterns in reporting behaviour resulting from different motivations for potential misrepresentation. This allows for examining the stability of the (mis)reporting behaviour in different treatments. Agents are primarily driven by the consequences for themselves rather than by the consequences for the principal, while deciding on misreporting. Participants are willing to sacrifice a small gain for themselves in order to prevent a greater loss for the principal. If agents misreport, they do it in order to generate positive rather than negative consequences for themselves. Reports in favour of the principal, but fruitless or even costly for the agent are very rare. The experiment indicates also that pro-social agents report more truthfully than pro-self agents.  相似文献   

13.
We explicitly construct the Green’s function for the Dirichlet problem for polyharmonic equations in a ball in a space of arbitrary dimension. The formulas for the Green’s function are of interest in their own right. In particular, the explicit representations for a solution to the Dirichlet problem for the biharmonic equation are important in elasticity.  相似文献   

14.
研究在Andersen Spaxre模型中,当破产概率的初始边界已知的时候,根据更新方程和更新方程中函数的单调性来改进破产概率的边界,并进一步改进了严重损失函数G(x,y)的边界.  相似文献   

15.
Sufficient conditions are obtained for the convergence of difference schemes for the numerical solution of the Cauchy problem for a heat conduction equation in two space variables. The sufficient conditions are derived in a form similar to those for the convergence of a sequence of linear positive operators in the Korovkin theorem. As an application it is shown that difference schemes that are widely used in practice can easily be checked for convergence by these conditions.  相似文献   

16.
Shadow price principles applied to regulated pricing of natural gas   总被引:1,自引:0,他引:1  
Inclusion of the shadow prices for natural gas in a dynamic fuels model for the United States shows that the primary reason for the relatively large, fly-up in new marginal gas prices in the early 1980's was the release of the pent-up price effects of the U.S. government's price regulations. In accordance with principles, the shadow price of natural gas fell siginificantly following de-regulation of the highcost gas (section 107) in 1980, which represented the precursor for downward adjustments in marginal wellhead prices of new high-cost gas and drilling activity. The modeling results show that no significant fly-up in new marginal gas prices for lower-cost gas (section 102) is likely to occur in 1985, when its phased de-regulation ends and it is finally de-regulated, because no shadow price precursor currently exists for this gas. Shadow price principles clear up the primary misconceptions with regard to natural gas pricing. This application indicates the significance of shadow price principles for regulated pricing in general.  相似文献   

17.
We develop the method of optimal portfolio choice based on the concept of cost-efficiency in two directions. First, instead of specifying a payoff distribution in an unique way, we allow customer-defined constraints and preferences for the choice of a distributional form of the payoff distribution. This leads to a class of possible payoff distributions. We determine upper and lower bounds for the corresponding strategies in stochastic order and describe related upper and lower price bounds for the induced class of cost-efficient payoffs. While the results for the cost-efficient payoff given so far in the literature in the context of Lévy models are based on the Esscher pricing measure we use as alternative the method of empirical pricing measures. This method is well established in the literature and leads to more precise pricing of options and their cost-efficient counterparts. We show in some examples for real market data that this choice is numerically feasible and leads to more precise prices for the cost-efficient payoffs and for values of the efficiency loss.  相似文献   

18.
弱非性理论已被广泛用于流动稳定性理论及其它领域.然而其应用对某些问题虽是成功的,但对另一些问题,其结果却常不令人满意,特别是对转捩或自由剪切流中涡的演化这类问题,这时理论研究的目的不是寻找稳态解,而是预测演化过程.在本文中,我们将研究不成功的原因并建议一些改进的办法.  相似文献   

19.
It was investigated how risk estimates derived from the RERF life span study data sets for cancer incidence and mortality, respectively, differ between the two cities Hiroshima and Nagasaki, and the two sexes. This was done by estimating the excess risk for various age-at-exposure and time-since-exposure groups. The epidemiologically most reliable age group are those aged 20–39 years at the time of exposure. As expected, in this group, the relative risk for females in Hiroshima is higher than that for males; however, in Nagasaki, the relative risk for females is lower than that for males. When comparing the risks in the two cities for the same sex, the risks of cancer incidence and mortality of females exposed in Hiroshima are higher than those in Nagasaki. However, for the males, the risks of cancer incidence in Hiroshima are lower than in Nagasaki, and the risks of cancer mortality of males are very similar between both cities. All differences depend on age-at-exposure and time-since-exposure, and are at the borderline of being statistically significant. The absorbed dose of neutrons, for the same γ-dose, is about three times as high in Hiroshima than in Nagasaki for both sexes. Because of these observed risk differences between both cities, it does not appear to be possible to reliably estimate the relative biological effectiveness of neutrons as compared to that of γ-rays from these epidemiological data sets. No evidence was found in this analysis that the radiation weighting factors wR presently used for neutrons in radiation protection could severely underestimate the risks for somatic late effects induced by neutrons.  相似文献   

20.
浮体与自由面交线附近流场的奇异性   总被引:2,自引:0,他引:2  
  相似文献   

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