基于系统动力学的再制造分级回收机制研究

考虑旧件回收质量与回收数量的不确定性特征,在分析再制造系统与回收行为的基础上,构建再制造分级回收系统动力学模型,尝试借助分级回收机制调节回收不确定性,并对再制造系统的长期表现展开研究.仿真结果表明,合理分级回收有利于减少回收流的不确定性,降低相关再制造成本,促使再制造更快进入良性发展状态;再制造产能扩大决策兼顾再制造收益与再制造规模,是再制造持续快速发展的有利保证;检测成本越低、回收质量波动幅度越小,最优分级数越多.再制造企业实施分级回收机制,既可以促进再制造的持续发展,也可以激励消费者提供高回收质量的旧件并改进使用习惯.     

零售商价格领导权结构下考虑专利保护的闭环供应链定价策略

很多零售商常处于其所在供应链的主导地位,针对零售商具有价格领导权并且考虑专利保护的闭环供应链进行分析,运用博弈理论得到了零售商、原制造商和再制造商的最优策略,以及最优策略关于再制造成本节约的变化规律。研究表明:随着再制造成本节约的增加,最优单位专利许可费和废旧产品回收价格逐步增加,最优产品批发价格和销售价格逐步降低,并通过数值算例表明:零售商、再制造商和供应链系统的利润逐步增加,原制造商的利润逐步减少。     

政府补贴下考虑规模效应的动力电池梯次利用闭环供应链决策与协调

针对零售商主导的考虑政府补贴和规模效应的动力电池闭环供应链,研究成员最优决策及协调问题。分别在无补贴、补贴零售商、补贴制造商、补贴第三方回收商四种情形下,分析了补贴对象、规模效应、再制造动力电池比例对成员最优决策及利润的影响,并实现了闭环供应链的协调。研究表明:政府补贴能够降低零售价,提高回收率以及各成员利润;补贴第三方回收商相比补贴零售商和补贴制造商而言,回收率以及第三方回收商利润提高更为明显,补贴零售商和补贴制造商相比补贴第三方回收商而言,零售价降低、制造商和零售商利润提高更为明显;可用于再制造的废旧动力电池比例增大能够降低动力电池销售价格,提高动力电池回收率;第三方回收商规模效应的增大有利于降低零售价格,提高动力电池产品回收率及闭环供应链各成员收益。     

随机环境下考虑回收定价和销售定价的逆向供应链优化与协调研究

由再制造商和分销商组成的逆向供应链中,再制造商回收的废旧产品数量是与回收价格相关的随机变量,分销商面临的再制造产品需求是与销售价格相关的随机变量.再制造商决策回收价格并向分销商提供合同,分销商基于合同作出反应来决策订购数量和销售价格,目标是在随机回收和随机需求下最大化各自的期望利润.利用博弈论和优化理论,分别得到了分散式和集中式供应链系统下的最优决策,证明了分散式系统中的回收价格和再制造数量偏低而销售价格偏高,并提出了综合三种基本合同的供应链协调机制.最后通过数值仿真得到了系统参数对供应链决策和利润的影响.     

专利保护下快递包装回收再制造模式分析

针对专利保护下快递包装回收再制造模式选择问题进行研究.首先,分别构建了快递包装生产商"自收自造"、"他收自造"及"他收合造"三种模式,运用逆向归纳法进行求解,得到了三种模式下的最优决策、最优利润以及再制造成本节约是闭环供应链各方进行再制造的主要驱动力;其次,在联合回收模式下,基于消费者对回收价格敏感程度不同,讨论物流服务商和再制造商回收价格的高低,并将三种模型的回收量进行比较,给出快递包装生产商选择最优回收量的建议;再次,基于消费者对回收价格敏感程度和无偿回收量,得出快递包装生产商选择最优回收模式的范围;最后,通过模拟仿真,验证了结论的正确性.研究结果对快递包装生产企业具有实际指导意义.     

需求中断下具零售商激励的双渠道供应链价格与生产决策

研究了由一个制造商和一个零售商所组成的两周期双渠道供应链.在第一周期需求实现之前,建立了生产量;在第二周期,基于第一周期的生产量和需求的实现确定了最优销售价格,进而确定了最优的生产量,实现了生产量的优化.通过需求中断下制造商和零售商的垂直整合,讨论了中断情形下价格和生产量对利润的影响.实证结果证实,集中式供应链的最优价格决策受零售渠道顾客偏好和市场规模变化的影响较为显著.     

考虑退货情形下的闭环供应链双源库存控制策略

假设再制造闭环供应链由单个制造商和单个零售商组成,考虑制造商产品回收率、退货率和废旧产品再制造率的不确定性,建立再制造环节废旧产品的最优检测时间、购买时间和闭环供应链最低成本的数学模型.利用回收率、退货率和再制造率计算废旧产品的最优检测和购买的时间间隔,分析再制造环节中双源库存的成本最小化问题.研究表明:再制造环节可降低闭环供应链的双源库存成本,但随着回收率的增加,总成本先下降后增加;在回收率、退货率和再制造率三者共同作用下,最优检测和购买时间间隔的设置可降低双源库存成本,优化资源配置.     

碳限额与交易约束下的闭环供应链碳减排策略及协调研究

在碳限额与碳交易约束下,通过碳减排技术投入及废旧品回收再制造可减少碳排放,构建了闭环供应链的碳减排博弈模型,根据协调条件给出了相应的契约形式及参数.通过对闭环供应链模型的求解,得到了碳限额与交易约束下的最优碳减排率、最优回收率和最优订货量.数值分析结果表明:碳减排成本系数与碳减排率、生产量成反向变化关系,与回收率成正向变化关系,而与闭环供应链期望利润成倒U型变化关系;碳交易价格与碳减排率、产量、闭环供应链期望利润成正向变化关系,而与回收率成反向变化关系;碳限额量不影响碳减排率、产量、废旧产品回收率,但与闭环供应链期望利润成成正向变化关系;回收率与碳减排率、产量成反向变化关系,而与闭环供应链期望利润成倒U型变化关系.     

模糊环境下基于再制造闭环供应链的博弈问题研究

研究了模糊环境下基于再制造闭环供应链的博弈问题,通过考虑存在于回收过程,制造(再制造)过程及需求过程中的模糊不确定性,建立了三种不同的再制造闭环供应链博弈模型,给出了制造商和回收商(零售商)的最优均衡决策,分析了制造商和回收商(零售商)博弈能力对废旧产品的回收,制造(再制造)产品的销售及系统成员利润的影响.利用数值算例对所得结果和关键参数进行了分析.     

基于产品生命周期的闭环供应链定价和协调策略研究

研究产品生命周期条件下一个制造商、一个零售商组成的闭环供应链的定价和协调策略:制造商第一周期只生产新品,从第二周期开始生产再制造品,并负责回收。建立了两周期、多周期和无限周期下的分散决策模型和多周期下的集中决策模型,得到最优定价和生产策略。结果表明:两周期中,制造商和零售商应根据不同的成本节约额制定不同的批发价、零售价和生产量。多周期中,当成本节约额比较小时,除第一和最后一个周期外,制造商和零售商应采取相同的定价和生产策略;当成本节约额比较大时,除第一和最后两个周期外,制造商和零售商应采取相同的定价和生产策略。无限周期中,除第一周期以外,制造商和零售商都应该采取相同的定价和生产策略。在有限周期情况下,制造商和零售商应通过在前期制定比较低的批发价和零售价,以提高生产量和销售量,使得后期的回收量增大,达到降低成本的目的。通过引入收益共享契约制定合适的批发价和销售收入及再制造收益共享比率可以协调整个闭环供应链。算例验证了上述结论。     

Comparison among three pull control policies: kanban, base stock, and generalized kanban

This paper is concerned with maketostock pull control policies. A classical policy is the kanban policy. Another policy, very easy to implement, is the base stock policy. These two policies contain one design parameter per stage. A general control policy, known as the generalized kanban policy, can also be used to implement the pull mechanism. The generalized kanban policy includes, as special cases, the kanban and the base stock policies. This policy uses two parameters for each stage of the production system. The aim of this paper is to provide qualitative and quantitative comparisons of these three policies. The results of our study will help to choose the policy to implement in order to control a production system. We give practical rules. We also show that if there is no delay in filling orders, all three policies have similar costs. However, for the systems studied, we show that, if there is a delay in filling orders, generalized kanban systems and base stock systems yield close to optimal costs, which are lower than costs of kanban systems for the same service quality.     

Government Debt, Budget Surplus, and Popularity of Politicians

This paper sets up a positive model of government behavior to determine the optimal fiscal policy of a politician who aims to reach a certain target level of national debt and remain popular at the same time. We model explicitly the response of the citizens to the fiscal policy set by the politician. To that end, we assume that citizens form an equilibrium acceptance rate of savings and adjust dynamically this savings rate to the currently prevailing levels of government debt and primary surplus. The difference between the equilibrium acceptance rate of savings as formed by the public and the fiscal policy actually chosen by the politician determines the politician popularity. Using the Pontryagin maximum principle, we derive the optimal level of the fiscal policy and investigate its local stability depending on the parameters of the model. We show that cyclical strategies [that is, phases of saving (primary surplus) and spending (primary deficit)], may be optimal.     

Public facility location using dispersion,population, and equity criteria

From a practical perspective, the paper demonstrates that the appropriate use of dispersion, population, and equity criteria can lead to fairly good solutions with respect to the p-median objective. The only stipulation is that the decision maker verifies (through simple constraint checks) that the chosen locations meet the dispersion, population, and equity criteria. An empirical investigation is conducted to obtain appropriate values for these parameters. From a location science perspective, a new location model that accounts for equity and efficiency simultaneously is studied and analyzed. Specifically, the p-maxian problem with side constraints on dispersion, population, and equity is developed, its NP-completeness established, and valid inequalities and bounds derived. Computational tests show encouraging results.     

Optimal policy for a dynamic,non-stationary,stochastic inventory problem with capacity commitment

This paper studies a single-product, dynamic, non-stationary, stochastic inventory problem with capacity commitment, in which a buyer purchases a fixed capacity from a supplier at the beginning of a planning horizon and the buyer’s total cumulative order quantity over the planning horizon is constrained with the capacity. The objective of the buyer is to choose the capacity at the beginning of the planning horizon and the order quantity in each period to minimize the expected total cost over the planning horizon. We characterize the structure of the minimum sum of the expected ordering, storage and shortage costs in a period and thereafter and the optimal ordering policy for a given capacity. Based on the structure, we identify conditions under which a myopic ordering policy is optimal and derive an equation for the optimal capacity commitment. We then use the optimal capacity and the myopic ordering policy to evaluate the effect of the various parameters on the minimum expected total cost over the planning horizon.     

Directed graphs,Hamiltonicity and doubly stochastic matrices

We consider the Hamiltonian cycle problem embedded in singularly perturbed (controlled) Markov chains. We also consider a functional on the space of stationary policies of the process that consists of the (1,1)‐entry of the fundamental matrices of the Markov chains induced by the same policies. In particular, we focus on the subset of these policies that induce doubly stochastic probability transition matrices, which we refer to as the “doubly stochastic policies.” We show that when the perturbation parameter ? is sufficiently small the minimum of this functional over the space of the doubly stochastic policies is attained very close to a Hamiltonian cycle, provided that the graph is Hamiltonian. We also derive precise analytical expressions for the elements of the fundamental matrix that lend themselves to probabilistic interpretation as well as asymptotic expressions for the first diagonal element, for a variety of deterministic policies that are of special interest, including those that correspond to Hamiltonian cycles. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004     

Optimal admission control for two station tandem queues with loss

We consider a two-station tandem queue with a buffer size of one at the first station and a finite buffer size at the second station. Silva et al. (2013) gave a criterion determining the optimal admission control policy for this model. In this paper, we improve the results of Silva et al. (2013) and also solve the problem conjectured by Silva et al. (2013).     

IS-LM-BP模型下的内外部均衡政策分析

引入IS-LM—BP模型,讨论调整内部均衡和外部均衡的政策问题,进而利用状态空间分析方法构造动态系统模型来分析宏观经济政策．基于政府预期的政策目标,通过状态反馈设计方法,以政府购买、货币供给等宏观经济政策工具来达到预期的政策效果．     

RECURSIVE UTILITY,PRODUCTIVE GOVERNMENT EXPENDITURE AND OPTIMAL FISCAL POLICY

This paper employs a stochastic endogenous growth model extended to the case of a recursive utility function which can disentangle intertemporal substitution from risk aversion to analyze productive government expenditure and optimal fiscal policy, particularly stresses the importance of factor income. First, the explicit solutions of the central planner＇s stochastic optimization problem are derived, the growth maximizing and welfare-maximizing government expenditure policies are obtained and their standing in conflict or coincidence depends upon intertemporal substitution. Second, the explicit solutions of the representative individual＇s stochastic optimization problem which permits to tax on capital income and labor income separately are derived ,and it is found that the effect of risk on growth crucially depends on the degree of risk aversion,the intertemporal elasticity of substitution and the capital income share. Finally, a flexible optimal tax policy which can be internally adjusted to a certain extent is derived, and it is found that the distribution of factor income plays an important role in designing the optimal tax policy.     

经济政策不确定性、金融市场压力与黄金市场的溢出效应研究

基于信息溢出视角,本文采用溢出指数模型,考察经济政策不确定性、金融市场压力与黄金市场溢出效应的强度和方向,并结合滚动窗口检验,捕捉溢出效应的时变特征。此外,本文还研究21个代表性国家经济政策不确定性与金融市场压力、黄金市场双向溢出效应的异质性。实证结果表明：经济政策不确定性、金融市场压力与黄金市场之间的溢出效应呈现显著的时变特征,溢出效应在金融危机期间呈现快速上升趋势,且体现为经济政策不确定性、金融市场压力对黄金市场的净溢出,金融市场压力在溢出效应中起着更重要的作用;正向的金融市场压力冲击比负向的金融市场压力冲击带来的溢出效应更大;各国的经济政策不确定性对黄金市场存在净溢出效应,但不同国家在溢出强度和规模上呈现出差异性。     

Min(N,V)--策略休假的M/G/1排队系统分析

在一个M／G／1休假排队系统中，同时考虑N-策略和多重休假策略，休假终止准则为任一个条件满足，我们称其为Min（N，V）-策略。本文给出了在此策略下的排队系统的稳态队长、忙期分布等基本指标。首次使用条件等待时间方法得到稳态等待时间的LST（Laplace-Stieltjes transform），同时还列举了一个应用的实例。最后指出本文模型是几个已研究模型的推广。