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Corresponding to stochastic variable, it is a better choice to describe the market demand uncertainty of innovative products
with fuzzy variable because no historical data is available. Traditionally, possibility measure is regarded as the parallel
concept of probability measure. However, it is, in fact, the credibility measure that plays the role of probability measure!
Based on the credibility theory, this paper studies how to evaluate the safety stock of enterprise given desired product availability
when the node enterprise market demand of supply chain is described by Gauss fuzzy variable. Thereinafter, the authors discuss
the impact of required product availability and demand uncertainty on safety stock, compare the correlative issues with stochastic
demand, and get some useful results. 相似文献
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Xiang Li Yang Zhang Hau-San Wong Zhongfeng Qin 《Journal of Computational and Applied Mathematics》2009,233(2):264-278
Portfolio selection theory with fuzzy returns has been well developed and widely applied. Within the framework of credibility theory, several fuzzy portfolio selection models have been proposed such as mean–variance model, entropy optimization model, chance constrained programming model and so on. In order to solve these nonlinear optimization models, a hybrid intelligent algorithm is designed by integrating simulated annealing algorithm, neural network and fuzzy simulation techniques, where the neural network is used to approximate the expected value and variance for fuzzy returns and the fuzzy simulation is used to generate the training data for neural network. Since these models are used to be solved by genetic algorithm, some comparisons between the hybrid intelligent algorithm and genetic algorithm are given in terms of numerical examples, which imply that the hybrid intelligent algorithm is robust and more effective. In particular, it reduces the running time significantly for large size problems. 相似文献
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设置安全库存可以有效管理供应链的不确定性,提高服务水平,降低缺货风险.本文基于可信性理论,研究了当需求为模糊变量,提前期分别为固定值和模糊变量时.节点企业安全库存量的确定问题.通过实际算例,分析了模糊环境下提前期对安全库存量的影响. 相似文献
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基于可信性理论和两阶段模糊优化方法,提出一类带有模糊参数的两阶段运输期望值模型.由于提出运输问题包含带有无限支撑的模糊变量系数,因此它是一个无限堆的优化问题.然后,讨论两阶段模糊运输期望值问题的逼近方法并且将逼近方法嵌套到遗传算法中产生一个基于遗传算法的逼近方法求解提出的两阶段模糊运输期望值问题.最后,给出一个数值例子... 相似文献
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So far, there have been several concepts about fuzzy random variables and their expected values in literature. One of the
concepts defined by Liu and Liu (2003a) is that the fuzzy random variable is a measurable function from a probability space
to a collection of fuzzy variables and its expected value is described as a scalar number. Based on the concepts, this paper
addresses two processes—fuzzy random renewal process and fuzzy random renewal reward process. In the fuzzy random renewal
process, the interarrival times are characterized as fuzzy random variables and a fuzzy random elementary renewal theorem
on the limit value of the expected renewal rate of the process is presented. In the fuzzy random renewal reward process, both
the interarrival times and rewards are depicted as fuzzy random variables and a fuzzy random renewal reward theorem on the
limit value of the long-run expected reward per unit time is provided. The results obtained in this paper coincide with those
in stochastic case or in fuzzy case when the fuzzy random variables degenerate to random variables or to fuzzy variables. 相似文献
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In this paper, an optimal production inventory model with fuzzy time period and fuzzy inventory costs for defective items is formulated and solved under fuzzy space constraint. Here, the rate of production is assumed to be a function of time and considered as a control variable. Also the demand is linearly stock dependent. The defective rate is taken as random, the inventory holding cost and production cost are imprecise. The fuzzy parameters are converted to crisp ones using credibility measure theory. The different items have the different imprecise time periods and the minimization of cost for each item leads to a multi-objective optimization problem. The model is under the single management house and desired inventory level and product cost for each item are prescribed. The multi-objective problem is reduced to a single objective problem using Global Criteria Method (GCM) and solved with the help of Fuzzy Riemann Integral (FRI) method, Kuhn–Tucker condition and Generalised Reduced Gradient (GRG) technique. In optimum results including production functions and corresponding optimum costs for the different models are obtained and then are presented in tabular forms. 相似文献
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Using a concept of random fuzzy variables in credibility theory, we formulate a credibilistic model for unichain Markov decision processes under average criteria. And a credibilistically optimal policy is defined and obtained by solving the corresponding non-linear mathematical programming. Also we give a computational example to illustrate the effectiveness of our new model. 相似文献
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In this paper, the capacitated location-routing problem with fuzzy demands (CLRP-FD) is considered. In CLRP-FD, facility location problem (FLP) and vehicle routing problem (VRP) are observed simultaneously. Indeed, the vehicles and the depots have a predefined capacity to serve the customers that have fuzzy demands. To model this problem, a fuzzy chance constrained programming model of that is designed based upon the fuzzy credibility theory. To solve this problem, a greedy clustering method (GCM) including the stochastic simulation is proposed. To obtain the best value of the dispatcher preference index of the model and to analyze its influence on the final solution, numerical experiments are carried out. Finally, to show the performance of the greedy clustering method, associated results are compared with the lower bound of the solutions. 相似文献