模糊环境下提前期对安全库存的影响

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.     

动态随机生产函数模型中库存量的确定

生产制造系统在某种程度上具有不确定性,库存量是影响生产系统的诸多随机变量之一,它随着市场需求、库存成本、企业生产能力等的改变而改变.本文以原有的动态随机生产函数模型为基础,通过在模型中引入库存变化这一随机因素,对该理论模型进行了改进与扩充,使其更加符合生产系统的实际.     

带有模糊参数的农业生产计划模型

在现实的生产系统中, 由于材料价格, 产品价格, 市场需求以及劳动者能力等不确定因素的影响, 生产计划问题常常是一个不确定规划问题. 因此, 带有常系数的生产计划模型不能准确有效的描述生产决策环境. 基于可信性理论, 本文将提出一类新的带有模糊参数的生产计划模型. 然后, 我们讨论了可信性函数的逼近并且设计一个基于逼近方法、神经网络和遗传算法的启发式算法来求解这个模糊生产计划问题. 最后, 给出了一个数值例子来表明所设计算法的可行性和有效性.     

基于可信性安全准则的模糊动态投资组合模型

研究了模糊环境下的动态投资组合模型,将证券的收益率描述为模糊变量,提出了基于可信性测度的安全准则,可信性安全准则反映了投资者对灾难事件的容忍水平.建立了基于可信性安全准则的模糊动态投资组合模型,对建立的模型设计了基于模糊模拟的混合智能算法进行求解,并在Visual C++环境下,用C语言实现了对实例的求解,证明了混合智能算法的有效性和合理性.     

基于可信性理论的PPP项目特许期-价格联合调整策略研究

需求预测误差是影响PPP项目收益预测准确性的主要因素。为减少谈判争议,确保风险和收益的动态均衡,本文基于模糊数学可信性理论,构建了考虑需求不确定的特许期-价格联合调整模型。将项目运营期间的需求预测误差作为模糊变量,将运营期内特许期和价格的联合调整策略作为决策变量,通过模糊模拟求解出不同特许期和价格调整组合下的期望收益误差以及正收益预期下的可信性,进而得到特许期和价格的联合调整策略可行解集。并将该模型应用于某污水项目中,结果表明,该模型能够有效地解决需求不确定性风险对特许期测算影响的问题,弥补了目前PPP项目特许期和价格调整决策研究中未考虑需求预测误差的不足,对PPP项目特许期和价格的调整决策有着重要的参考意义。     

Dynamic pricing model and algorithm for perishable products with fuzzy demand

This paper studies the dynamic pricing problem of selling fixed stock of perishable items over a finite horizon, where the decision maker does not have the necessary historic data to estimate the distribution of uncertain demand, but has imprecise information about the quantity demand. We model this uncertainty using fuzzy variables. The dynamic pricing problem based on credibility theory is formulated using three fuzzy programming models, viz.: the fuzzy expected revenue maximization model, α‐optimistic revenue maximization model, and credibility maximization model. Fuzzy simulations for functions with fuzzy parameters are given and embedded into a genetic algorithm to design a hybrid intelligent algorithm to solve these three models. Finally, a real‐world example is presented to highlight the effectiveness of the developed model and algorithm. Copyright © 2009 John Wiley & Sons, Ltd.     

A survey of credibility theory

This paper provides a survey of credibility theory that is a new branch of mathematics for studying the behavior of fuzzy phenomena. Some basic concepts and fundamental theorems are introduced, including credibility measure, fuzzy variable, membership function, credibility distribution, expected value, variance, critical value, entropy, distance, credibility subadditivity theorem, credibility extension theorem, credibility semicontinuity law, product credibility theorem, and credibility inversion theorem. Recent developments and applications of credibility theory are summarized. A new idea on chance space and hybrid variable is also documented.     

Knight不确定下基于无穷纯跳Levy过程的一般风险资产的动态最小定价

研究了具有Knight不确定性的金融市场下的一般风险资产的动态最小定价,利用倒向随机微分方程(BSDE)理论以及时间-风险折现方法,推导出了基于无穷纯跳Levy过程的一般风险资产在实际概率测度下的动态定价公式及其在Knight不确定性控制集合上的动态最小定价.最后给出了一个欧式看涨期权动态最小定价的例子,并导出期权价格的显示表达式.在Knight不确定环境下,引入Levy过程来描述股票价格的动态走势,更加符合实际市场,可广泛地应用于一般风险资产的定价过程,这为投资分析提供一定的理论依据.     

基于可信性理论的均值-熵-偏度投资组合模型及其算法求解

本文考虑到证券市场的投资者往往面临着随机和模糊两种不确定性的情形,在模糊随机环境下把证券的收益率视作三角模糊变量,在可信性理论基础上建立了带融资约束条件的均值-熵-偏度三目标投资组合决策模型,拓展了基于可信性理论的投资组合决策模型的研究内容,同时通过对约束条件处理方法,外部档案维护方法等关键算子的改良,提出了一种新的约束多目标粒子群算法。本文运用该算法对模型进行求解,把得到的最优解与传统的多目标粒子群算法得到的最优解进行对比,结果表明新算法得到的最优解的质量会显著地优于传统的多目标粒子群算法的最优解,从而验证了算法的有效性和准确性。该算法可以在三维空间中得到一个分布性和逼近性较好的Pareto最优曲面,满足投资者对不同目标的差异需求,为投资者提供合理的投资组合决策方案。     

Optimal production inventory policy for defective items with fuzzy time period

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.     

随机模糊需求报童问题

考虑到需求的随机模糊性,建立了随机模糊需求报童的利润模型。利用可信性测度理论给出了其期望利润模型,并揭示了期望利润函数的凹性,证明了最优订货量的存在性和唯一性。结合随机模糊模拟技术和随机扰动近似算法设计了求解最优订货量的混合算法。最后,通过数值算例说明了算法的有效性。     

A risk approach by credibility theory

This paper attempts to treat some topics of risk theory by means of credibility theory. We study the risk aversion of an agent faced with a situation of uncertainty represented by a discrete fuzzy variable, the relationship between stochastic dominance and credibilistic dominance, and an index of riskiness of discrete credibilistic gambles. In the framework of an optimal saving credibilistic model, the way the presence of risk modifies the level of optimal saving is studied. The main tool of our investigation is an operator defined by B. Liu and Y. K. Liu by which to a discrete fuzzy variable one associates a discrete random variable with the same expected value as the former.     

模糊需求下的供应链收益共享契约模型

在模糊需求环境下,研究由单一供应商和零售商组成的两级供应链系统的协调机制问题。将市场需求视为模糊变量,建立不确定理论下,基于可信性分布的集成供应链模型和收益共享契约模型,并给出了模型中的最优策略。最后,以三角形模糊变量为例,通过数值算例对模型中的参数进行了求解,并分析批发价格和收益系数对其他参数的影响。研究结果表明,零售商的最优订购量在模糊需求中心点的左、右浮动,并随着零售价格的提高而增加;不同的收益系数对应不同的批发价格策略;通过改变收益系数可以实现供应链成员之间的完美协调。     

An extension of the Clark–Haussmann formula and applications

ABSTRACT

This work considers a financial market stochastic model where the uncertainty is driven by a multidimensional Brownian motion. The market price of the risk process makes the transition between real world probability measure and risk neutral probability measure. Traditionally, the martingale representation formulas under the risk neutral probability measure require the market price of risk process to be bounded. However, in several financial models the boundedness assumption of the market price of risk fails; for example a financial market model with the market price of risk following an Ornstein–Uhlenbeck process. This work extends the Clark–Haussmann representation formula to underlying stochastic processes which fail to satisfy the standard requirements. Our methodology is classical, and it uses a sequence of mollifiers. Our result can be applied to hedging and optimal investment in financial markets with unbounded market price of risk. In particular, the mean variance optimization problem can be addressed within our framework.     

A generalized Borgonovo's importance measure for fuzzy input uncertainty

In this work, the way in which fuzzy uncertainty in a model's output is apportioned to fuzzy uncertainty in model inputs is studied through a sensitivity analysis. Here, an optimization technique is employed to obtain the membership functions of the fuzzy structural response, for which a global sensitivity indicator is introduced to measure the influence of fuzzy input uncertainty on fuzzy output uncertainty. The global sensitivity indicator is the important measure of the fuzzy input uncertainty, which extends Borgonovo's measure. In this study, the mathematical properties of the important measure of the fuzzy input uncertainty are discussed and proved. The results of numerical examples and engineering examples show that the proposed importance measure can effectively describe the effect of fuzzy input uncertainty on fuzzy structural response. When the sensitivity indicator is larger, the basic fuzzy-valued variable becomes more important. The sensitivity indicators of the fuzzy structural response can give an essential importance sequence of all the basic fuzzy-valued variables and identify key contributing fuzzy-valued variables. The sensitivity indicators can provide the availability guidance to reduce the number of basic variables and optimize the fuzzy response model.     

农产品供应链质量安全中区块链技术投入的演化分析

针对农产品质量安全的不确定性,及引入区块链技术能提高农产品质量安全溯源信息的可信度,建立了基于区块链技术投入的农产品供应商与加工者的演化博弈模型,并对模型的动力系统和策略稳定性进行了分析和系统模拟仿真。研究发现：企业进行区块链技术投入的策略与其投入后市场需求增加率有直接关系,随着市场需求增加率的变化,系统出现多种演化稳定均衡。政府的补贴机制,能解决企业进行区块链技术投入中存在的“搭便车”问题;促使供应链的成员企业均进行区块链技术投入。研究结果对政府策略的制定和企业进行区块链技术投入决策具有一定的启示。     

Safety Stock Determination with Serially Correlated Demand in a Periodic-Review Inventory System

We consider a periodic-review inventory replenishment model with an order-up-to-R operating doctrine for the case of deterministic lead times and a covariance-stationary stochastic demand process. A method is derived for setting the inventory safety stock to achieve an exact desired stockout probability when the autocovariance function for Gaussian demand is known. Because the method does not require that parametric time-series models be fit to the data, it is easily implemented in practice. Moreover, the method is shown to be asymptotically valid when the autocovariance function of demand is estimated from historical data. The effects on the stockout rate of various levels of autocorrelated demand are demonstrated for situations in which autocorrelation in demand goes undetected or is ignored by the inventory manager. Similarly, the changes to the required level of safety stock are demonstrated for varying levels of autocorrelation.     

基于可信性理论的两阶段生产计划模型

为了准确有效地处理农业生产中的不确定性因素,基于可信性理论和两阶段模糊优化方法提出一类新的带有最小风险准则的两阶段模糊农业生产计划模型.然后,讨论可信性函数的逼近方法并且设计一个基于逼近方法、神经网络和模拟退火的启发式算法来求解这个两阶段模糊农业生产计划最小风险模型.最后,给出一个数值例子来表明所设计算法的可行性和有效性.     

风险的动态定量和一个相关的随机对策问题

本文讨论不完全市场中股票收益率不确定时的动态风险度量问题和一个相关的随机对策问题。该动态风险度量可表示为一个随机最优控制问题的值函数,以倒向随机微分方程为工具我们给出了最优目标具有的形式,并给出随机对策问题上值与下值相等的充分条件和鞍点的存在性。     

不确定性对混合CVaR约束库存系统的影响

运用应用概率中的随机占优研究需求不确定性对混合CVaR约束库存系统最优订购量和最优利润的影响。引入刻画决策者风险态度的“风险偏好系数”,得到系统最优订购量和最优利润关于风险偏好系数的单调性。研究表明随机大需求总会导致系统较高的最优订购量和最优利润;在割准则序意义下,最优订购量可能随需求可变性的增加而增加也可能随需求可变性的增加而减少;在二阶随机占优且风险偏好系数大于等于1的情况下系统最优利润具有随机单调性,然而当风险偏好系数小于1时最优利润在二阶随机占优意义下的结论不一定成立,我们通过一个数值例子来说明。