基于可控提前期和延迟供货的短生命周期产品库存模型

本文用斜坡型函数来描述短生命周期产品需求变化特征,用持有成本不断增加的形式来表示存货的无形变质所带来的损失,通过向供应商支付额外的赶工成本来缩短提前期,同时在允许缺货的情况下设置合理的缺货期价格折扣来控制订单的流失,即以价格折扣的损失来挽留住更多的顾客,使其总成本到达最优。本文在此基础上建立了短生命周期产品的库存模型,并提出了最优解的求解方法。     

基于需求预测的短生命周期产品订货策略研究

本文针对短生命周期产品的特点,考虑与需求因子相关的库存短缺拖后和无形变质,根据缺货时间点、订货时间点与产品到达成熟期的时间点之间的关系,建立基于短生命周期产品需求预测的3种订货策略模型:乐观订货策略,悲观订货策略和中庸订货策略模型,对模型进行了分析求解,对最优解的存在性进行了证明.然后根据实际销售数据进行需求预测和算例分析,分析各因子对于总库存成本、订货量、短缺拖后量、销售损失量以及最优订货策略的影响.最后通过订货策略分析,分析各因子对于最优订货策略的影响,并将它们划分为3种订货策略影响因子,分析结果可以指导企业在不同因子水平情况下如何调整订货策略,以降低总库存成本.     

持有成本和变质率时变的非立即变质品库存策略

本文主要研究非立即变质品的库存策略设计问题。以平均利润最大化为决策目标,构建了一个一般化的库存模型,假设需求受即时库存水平影响且在保鲜期和变质期内库存水平对需求的影响系数不同,持有成本和变质期内的变质率均随时间发生变化,系统允许缺货且短缺量部分延迟订购。进一步证明了当参数满足一定条件时,模型存在唯一的最优解。最后,采用牛顿法给出一些具体的数值算例,并对模型中主要参数的灵敏度进行了分析。结果显示:延长物品的保鲜期将有助于增加系统的平均利润;增加变质期内的需求比增加保鲜期内的需求更有利于增加系统的平均利润;对于变质率高的产品来说,其变质处理成本对最优策略和平均利润的影响不容忽视。此外,本文所构建的模型具有一般性,因此,其应用范围更加广泛。     

周期性需求下基于延迟订货的库存控制

本文在假设产品需求为周期性需求,订货周期为需求周期的整数倍,不能满足的需求在一定的时间间隔内允许缺货的前提下,提出一种确定性库存模型,并在此基础上,以满足单位时间内利润最大化为目标,研究并确定了优化订货批量、订货周期的时间间隔长度和缺货的时间长度的算法,最后给出算例,并验证了算法的可行性.     

需求率符合市场生命周期变化的易腐库存控制研究

本文建立了需求率符合产品市场生命周期变化的易腐库存模型,并给出了求解该模型的解析方法.应用此模型可对易腐产品的库存控制做出最优的决策.     

单位保管和短缺成本均为时变的生产库存模型

基于短缺量拖后率不相同时的边生产边需求库存模型,进一步考虑单位保管和缺货成本与时间呈线性或非线性关系,建立了相应的生产库存模型.运用Mathematica5.0对模型进行仿真寻优和主要参数的灵敏度分析,结果表明,单位保管和缺货成本对库存系统各项成本影响较大,在制定库存控制策略时必须重点考虑这两个因素.     

模糊环境下的生产库存模型研究

本文提出了一种同时考虑缺货和缺陷品的生产库存模型,研究了在模糊环境下的生产库存优化求解问题.生产库存模型中所有要素均采用梯形模糊数来描述,并采用梯级平均综合表示法对目标函数解模糊.算例表明在模糊环境下研究生产库存模型可以有效地解决生产库存环境的不确定性问题.     

部分延迟订购的Weibull分布变质品库存策略研究

研究需求依赖于即时库存、变质服从Weibull分布、部分延迟订购且延迟订购率与等待时间相关的变质品库存优化策略.当需求依赖于库存水平时,利润最大化问题不能简化为成本最小化问题,所以以利润最大化为目标构建库存模型,并证明了最优解的存在性和唯一性,同时给出应用牛顿迭代法求解模型的具体步骤.最后,通过算例给出了模型的应用并对参数的灵敏度进行了分析.结果表明:延迟订购阻力、缺货成本或机会成本的增加会降低系统的利润同时要求提升系统的服务水平;系统的平均利润对购买成本比较敏感,而服务水平对库存持有成本非常敏感.     

基于产品生命周期的战略库存与动态定价决策研究

本文考虑一个基于短周期产品供应商和零售商组成的两级供应链系统,在两个销售周期内,市场容量根据产品所处的生命周期变化而变化。文章研究了在承诺定价合同和动态定价合同下,零售商使用战略库存策略和战略缺货策略的条件,以及产品在不同生命周期下供应商和零售商的最优决策和利润。研究发现,战略库存策略和战略缺货策略在两种定价合同下都可能存在,产品所处生命周期和持有(缺货)成本的大小对供应链成员的决策和利润起着决定性作用。战略库存策略在产品处于发展期时可以有效降低产品第二期批发价格,但战略缺货策略却不具备议价效果。同时,当第二周期产品市场容量变化不剧烈,且持有成本较小时,零售商在动态定价合同下使用战略库存策略可以同时提高供应商和零售商利润,进而提高整体供应链效率;零售商在动态定价合同下使用战略缺货策略同样可以提高整体供应链效率,但当供应商决定供应链成员间的定价方式时,战略缺货策略始终不会存在。     

一类供应链中多产品的订购策略及实证研究

本文针对变质产品供应链,建立了多产品的库存模型,分析了基于五种不同订购策略下总成本函数的性质,提出了多种变质商吕的近似最优订购策略.并且运用本文的理论,对南京市某花卉礼品公司2004年9月的鲜切花订购决策进行了实证分析.     

Economic order quantity model with trade credit financing for non-decreasing demand

Researchers in the past have established their inventory lot-size models under trade credit financing by assuming that the demand rate is constant. However, from a product life cycle perspective, it is only in the maturity stage that demand is near constant. During the growth stage of a product life cycle (especially for high-tech products), the demand function increases with time. To obtain robust and generalized results, we extend the constant demand to a linear non-decreasing demand function of time. As a result, the fundamental theoretical results obtained here are suitable for both the growth and maturity stages of a product life cycle. In addition, we characterize the optimal solutions and obtain conclusions on important and relevant managerial phenomena. Lastly, we provide several numerical examples to illustrate the proposed model and its optimal solution.     

A quick response production strategy to market demand

The reason for considering the quick response production strategy to market demand is due to the rapid technology change, which results in decreasing market price and obsolescence. This study considers a production strategy of locating final production line in response to the changes in market demand and the continuous deterioration in stock. The demand rate is assumed to decrease exponentially with time while the price is assumed to decrease linearly with time. The purpose of this study is to derive the most economical site of final-production line that assembles products with short life cycle. The model considered in this research takes into account the sales revenue, the deteriorating cost, the carrying cost, the variable cost and the fixed cost of production. Although there is a higher labour and material cost when the production site is located near market point, the total profit increases due to quicker responsive time, smaller import tax, lower inventory and lesser deteriorating cost.     

时变供需下基于商业信用的零售商最优订货策略

论文在时变供需环境下,即市场需求为斜坡式时间函数及补货率依赖于市场需求情境下,探讨了基于商业信用的供应链中零售商最优订货策略。首先,根据商业信用期和零售商补货周期的关系,分两种情形构建了零售商库存模型;其次,根据零售商的库存模型,证明了其最优解的存在,并给出相关的命题和算法来求解零售商的最优库存策略;最后,通过数值算例和灵敏度分析来论证文中的有关结论。研究发现:当供应商给予零售商的商业信用期较短时,此时市场需求仍处于增长期,随着市场需求稳定时间点的增大,零售商的最优订货周期逐渐减小,最优订货量和年费用也逐渐减小;当供应商给予零售商的商业信用期较长时,此时市场需求已趋于稳定期,随着市场需求稳定时间点的增大,零售商的最优订货周期逐渐增大,最优订货量和年费用也逐渐增大;当供应商生产与市场需求依赖性逐渐增大时,零售商的最优订货周期逐渐增大,最优订货量及年费用也逐渐增大。     

Grocery Perishables Management

In this article, we study the joint pricing and inventory control problem for perishables when a retailer does not sell new and old inventory at the same time. At the beginning of a period, the retailer makes replenishment and pricing decisions, and at the end of a period, the retailer decides whether to dispose of ending inventory or carry it forward to the next period. The objective of the retailer is to maximize the long‐run average profit. Assuming zero lead time, we propose an efficient solution approach to the problem, which is also generalized to solve three extensions to the basic model. A feature of the present study is that we consider explicitly the influence of perishability on the demand. Among the insights gathered from the numerical analysis, we find that dynamic pricing aids extending shelf life and when disposal incurs a lower cost, or even a positive salvage value, the retailer is induced to dispose earlier since the benefit of selling new inventory offsets the loss due to disposal. We also observe that the faster the perceived rate of deterioration, the lower the threshold of the ending inventory for disposal. Perhaps a bit counter‐intuitive, maximizing profits does not mean eliminating disposals or expirations.     

Optimal price,warranty length and production rate for free replacement policy in the static demand market

In the present paper, a decision model is developed for producers in the static demand market to determine the optimal price, warranty length and production rate of a product to maximize profit based on the pre-determined life cycle. The free renewal warranty policy is considered under which failed products are renewed before the end of warranty length at no cost to consumers. The expected number of renewals based on warranty length is derived for Weibull life distributed products. The objective function includes both demand and cost functions, where production cost, warranty cost and inventory cost are involved. A solution approach using the maximum principle is described, and is applied to two specific cases of markets. The first case of market considers positive discount rate, and the second case of market considers zero discount rate. The economic sensitivity analysis is conducted to evaluate the effect of model parameters on the optimal solution. Some conclusions are drawn based on the sensitivity analysis.     

A Bayesian Inventory Model Using Real‐Time Condition Monitoring Information

Lack of coordination between machinery fault diagnosis and inventory management for spare parts can lead to increased inventory costs and disruptions in production activity. We develop a framework for incorporating real‐time condition monitoring information into inventory decisions for spare parts. We consider a manufacturer who periodically replenishes inventory for a machine part that is subject to deterioration. The deterioration is captured via condition monitoring and modeled using a Wiener process. The resulting degradation model is used to derive the life distribution of a functioning part and to estimate the demand distribution for spare parts. This estimation is periodically updated, in a Bayesian manner, as additional information on part deterioration is obtained. We develop an inventory model that incorporates this updated demand distribution and demonstrate that a dynamic base‐stock policy, in which the optimal base‐stock level is a function of some subset of the observed condition monitoring information, is optimal. We propose a myopic critical fractile policy that captures the essence of the optimal policy, but is easier to compute. Computational experiments indicate that this heuristic performs quite well relative to the optimal policy. Adaptive inventory policies such as these can help manufacturers to increase machine availability and reduce inventory costs.     

Optimizing inventory and marketing policy for non-instantaneous deteriorating items with generalized type deterioration and holding cost rates

This paper considers an inventory system with non-instantaneous deteriorating item in which demand rate is a function of advertisement of an item and selling price. This paper aids the retailer in maximizing the total profit by determining optimal inventory and marketing parameters. In contrast to previous inventory models, an arbitrary holding cost rate and arbitrary deterioration rate have been incorporated to provide general framework to the model. First, a mathematical model is formulated and then some useful theoretical results have been framed to characterize the optimal solutions. The necessary and sufficient conditions for the existence and uniqueness of the optimal solutions are also derived. An algorithm is designed to find the optimum solutions of the proposed model. Numerical examples are included to illustrate the algorithmic procedure and the effects of key parameters are studied to analyze the behavior of the model.     

An EOQ inventory model for items with Weibull distribution deterioration,ramp type demand rate and partial backlogging

In this paper, an EOQ inventory model is presented depleted not only by demand but also by Weibull distribution deterioration, in which the demand rate is assumed that with a ramp type function of time. In the model, shortages are allowed partial backlogging and the backlogging rate is variable and is dependent on waiting time for the next replenishment. The method is illustrated by three numerical examples, and sensitivity analysis of the optimal solution with respect to parameters of the system is carried out.