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161.
中国股市收益率分布函数研究 总被引:14,自引:6,他引:14
本文在考察了文献中描述股票收益率的各类分布函数的基础上,以稳定Paretian分布与t分布为备择,研究了沪、深股市各类综指收益率的分布函数的形式,并对分布函数的参数进行了估计。 相似文献
162.
163.
On the Effect of Probability Distributions of Input Variables in Public Health Risk Assessment 总被引:1,自引:0,他引:1
A central part of probabilistic public health risk assessment is the selection of probability distributions for the uncertain input variables. In this paper, we apply the first-order reliability method (FORM)(1–3) as a probabilistic tool to assess the effect of probability distributions of the input random variables on the probability that risk exceeds a threshold level (termed the probability of failure) and on the relevant probabilistic sensitivities. The analysis was applied to a case study given by Thompson et al. (4) on cancer risk caused by the ingestion of benzene contaminated soil. Normal, lognormal, and uniform distributions were used in the analysis. The results show that the selection of a probability distribution function for the uncertain variables in this case study had a moderate impact on the probability that values would fall above a given threshold risk when the threshold risk is at the 50th percentile of the original distribution given by Thompson et al. (4) The impact was much greater when the threshold risk level was at the 95th percentile. The impact on uncertainty sensitivity, however, showed a reversed trend, where the impact was more appreciable for the 50th percentile of the original distribution of risk given by Thompson et al. 4 than for the 95th percentile. Nevertheless, the choice of distribution shape did not alter the order of probabilistic sensitivity of the basic uncertain variables. 相似文献
164.
Estimation from Zero-Failure Data 总被引:2,自引:0,他引:2
Robert T. Bailey 《Risk analysis》1997,17(3):375-380
When performing quantitative (or probabilistic) risk assessments, it is often the case that data for many of the potential events in question are sparse or nonexistent. Some of these events may be well-represented by the binomial probability distribution. In this paper, a model for predicting the binomial failure probability, P , from data that include no failures is examined. A review of the literature indicates that the use of this model is currently limited to risk analysis of energetic initiation in the explosives testing field. The basis for the model is discussed, and the behavior of the model relative to other models developed for the same purpose is investigated. It is found that the qualitative behavior of the model is very similar to that of the other models, and for larger values of n (the number of trials), the predicted P values varied by a factor of about eight among the five models examined. Analysis revealed that the estimator is nearly identical to the median of a Bayesian posterior distribution, derived using a uniform prior. An explanation of the application of the estimator in explosives testing is provided, and comments are offered regarding the use of the estimator versus other possible techniques. 相似文献
165.
This paper presents a genetic algorithm (GA) for parallel redundancy optimization in series-parallel power systems exhibiting
multi-state behavior, optimizing the reliability subject to constraints. The components are binary and chosen from a list
of products available in the market, and are being characterized by their feeding capacity, reliability, cost and weight.
System reliability is defined as the ability to satisfy consumer demand and is presented as a piecewise cumulative load curve.
In GA, to handle infeasible solutions penalty strategies are used. Penalty technique keep a certain amount of infeasible solutions
in each generation so as to enforce genetic search towards an optimal solution from sides of, both, feasible and infeasible
regions. We here present a dynamic adaptive penalty function which helps the algorithm to search efficiently for optimal/near
optimal solution. To evaluate system reliability, a fast procedure, based on universal generating function, is used. An example
considering a multi-state series-parallel power system is solved considering both homogeneous and heterogeneous types of redundancy.
Also an example considering price discounts is solved. The effectiveness of the penalty function and the proposed algorithm
is studied and shown graphically. 相似文献
166.
F. H. Chang H. B. Chen J. Y. Guo F. K. Hwang Uriel G. Rothblum 《Journal of Combinatorial Optimization》2006,11(3):321-339
Consider the problem of partitioning n nonnegative numbers into p parts, where part i can be assigned ni numbers with ni lying in a given range. The goal is to maximize a Schur convex function F whose ith argument is the sum of numbers assigned to part i.
The shape of a partition is the vector consisting of the sizes of its parts, further, a shape (without referring to a particular
partition) is a vector of nonnegative integers (n1,..., np) which sum to n. A partition is called size-consecutive if there is a ranking of the parts which is consistent with their sizes, and all
elements in a higher-ranked part exceed all elements in the lower-ranked part. We demonstrate that one can restrict attention
to size-consecutive partitions with shapes that are nonmajorized, we study these shapes, bound their numbers and develop algorithms
to enumerate them. Our study extends the analysis of a previous paper by Hwang and Rothblum which discussed the above problem
assuming the existence of a majorizing shape.
This research is partially supported by ROC National Science grant NSC 92-2115-M-009-014. 相似文献
167.
168.
测试实数编码遗传算法的困难度 总被引:3,自引:0,他引:3
分析了遗传算法困难度测试在遗传算法研究中的重要意义. 鉴于当前这方面的研究集
中于二进制编码遗传算法,对实数编码遗传算法的困难度测试进行了分析. 探讨了实数编码遗
传算法困难度分析的适应值与距离相关系数测试法与基于随机游走模型的相关函数测试法,
提出了最佳一阶函数逼近测试法,做了大量实验,并根据实证分析结果对三种方法进行了比较
与评价. 相似文献
169.
生产函数与成本函数的关系研究 总被引:6,自引:1,他引:6
本文给出了生产函数与成本函数之间的一般关系,并证明齐次生产函数与齐次成本函数之间存在着一种齐次对应关系:齐次生产函数在厂商的成本最小化决策下必然产生齐次的成本函数且齐次成本函数必然产生对应于齐次的生产函数。 相似文献
170.
高校青年志愿服务是社会志愿服务中重要的组成部分。高校青年志愿服务事业由四个子系统承担着相应的功能:资源系统发挥适应功能;高校志愿服务组织发挥目标达成功能;共青团发挥整合功能;育人系统发挥模式维持功能。在目前的高校志愿服务工作中,各项功能存在发挥不到位的问题。以AGIL理论分析模型为框架,可以从四个方面促进高校青年志愿服务提供路径支撑:资源系统做好社会化发展、高校志愿服务组织做好项目化管理、共青团做好枢纽化整合、育人系统做好价值化引领,从而发挥有机整体的作用。 相似文献