一类考虑机器可靠性的变质性物品供应商管理库存

在考虑机器可靠性和通货膨胀的情形下,建立一个供应商和一个订货商,在允许订货商缺货且缺货量部分拖后的易变质产品的供应商管理库存(VMI,Vendor Managed Inventory)模型,给出了数值算例、最优解及主要参数的图形分析,结果表明参数对供应链库存成本均有一定程度的影响,为VMI模式下的库存管理系统提供一些理论依据.     

VMI下价格补贴机制协调模型研究

以零售商和供应商组成的供应商管理库存(VMI)供应链系统为研究对象,考虑随机需求下VMI系统中可能存在滞销成本和缺货惩罚,建立传统、Stackelberg博弈、相同权力Nash协商、不同权力Nash协商的4种价格补贴机制的协调模型。通过数值分析得出:价格补贴机制下传统的VMI协调的不合理性;Stackelberg博弈的VMI协调达不到集成供应链整体收益,但可使零售商和供应商收益得到改善;相同权力和不同权力的Nash协商均能完美协调分散式VMI,零售商与供应商各自增加的收益在协商权力相同时是相等的,在协商权力不同时与自身协商权力正相关。     

基于 Multi-agent的库存管理优化

本文研究了供应商库存管理(vendor management inventory，VMI)系统优化问题。利用Multi—agent技术构建了VMI数学模型，VMI模型由三个模块组成，各个模块的功能分别由一个agent实现，借助于遗传算法实现了货物配送最优化。     

水产品供应商管理库存(VMI)模型的设计

供应商管理库存VMI（vendor managed inventory）技术是供应链管理理论出现以后提出来的一种新的库存管理模式，其主要目的是将供应链上的整体存货水平降到置低限度。结合水产品及其库存管理的特点，本文分析了水产品供应商管理库存（VMI）的基本特征，在此基础上构建了一个适用于水产品的VMI模型。     

需求依赖库存且有时变短缺拖后率的非立即变质物品库存模型

研究了时变短缺部分拖后条件下非立即变质性物品的库存补给模型,其中物品的变质率随时间变化而变化。当库存水平为正值时,市场需求受销售价格影响;当库存为负值时,不能满足的需求被部分拖后,拖后率与在缺货期间已经发生的缺货量有关。通过考虑短缺拖后率和变质率同时随时间变化对库存补给策略的影响,建立具有短缺量部分拖后的非立即变质性物品的库存模型,并且给出模型最优解存在的必要条件,得到一类更加符合实际情形的库存模型。最后,用数值算例说明模型的实际应用。     

VMI下供应链库存模型研究

分别建立了供应链在实行VMI模式前后的供应链整体、供应商及下游企业的定价、成本及利润模型,通过前后的比较分析了VMI模式的实施前期和实施一段时间后对供应链整体、供应商及其下游企业成本、利润、购买价格、订购量的影响。     

基于第三方的易变质产品库存决策

针对需求受价格影响和需求受价格、库存量共同影响的两种情况,考虑销售商允许缺货且缺货期间出现短缺量部分拖后,研究多个供应商、多个销售商情况下,供应商库存外包于第三方的易变质产品库存联合决策模型.对比分析两模型的结论表明,需求依赖当前销售价格和库存量情况下,考虑易变质产品库存问题更贴近实际,存在最优订货周期、最优销售价格使得供应链整体利益最大化,此时,供应链整体利润并不随着缺货率的增加而单调减小.     

双源采购跳跃-扩散库存控制模型

供应中断和退货会引发库存短缺和剧烈波动,所以,如何缓解它们的影响,成为当前企业管理者亟待解决的难题.在采用双源采购策略防御库存短缺和跳跃-扩散过程描述库存水平变化条件下,利用连续时间Markov链、水平穿越和鞅理论,分别确定了库存水平分布及循环的期望费用和时间函数,在此基础上,构建了系统长程平均费用率模型.最后,仿真结果表明,供应商的可靠性和中断类型,对最优控制策略和系统费用产生较大影响.另外,双源采购策略能够有效缓解供应中断对库存的影响,尤其是,当供应商的可靠性较低或中断类型均为频率低持续时间长时.     

基于RosettaNet标准的VMI系统的研究

供应商管理库存（VMI）通过降低供应链上的库存水平以及物料流转周期,从而降低了总成本,已经被越来越多地应用到企业的电子商务系统中。在传统的VMI管理模式中,传真、EMAIL等手工方式问题非常多;而使用EDI标准也存在费用高昂、交易流程定制复杂等问题。提出了一种基于RosettaNet标准的VMI系统的解决方案。它采用了基于Roset-taNet规范的标准流程,提供了稳定可靠的底层架构,能够完成数据高效的传输,并且具有一定的数据分析能力。     

基于RosettaNet标准的VMI系统的研究

供应商管理库存(VMI)通过降低供应链上的库存水平以及物料流转周期,从而降低了总成本,已经被越来越多地应用到企业的电子商务系统中。在传统的VMI管理模式中,传真、EMAIL等手工方式问题非常多;而使用EDI标准也存在费用高昂、交易流程定制复杂等问题。提出了一种基于RosettaNet标准的VMI系统的解决方案。它采用了基于Roset-taNet规范的标准流程,提供了稳定可靠的底层架构,能够完成数据高效的传输,并且具有一定的数据分析能力。     

Inventory model with a mixture of back orders and lost sales

Very few researchers have considered inventory models with partial backlogging. The models developed earlier considered a fraction of demand to be backordered while the remaining fraction is lost during the stock out period. In this paper we have developed an inventory model with partial backlogging, redefining the demand rate at a particular instant as a function of the amount of orders already backlogged at that instant of time. Infinite replenishment rate and zero lead time are assumed. Expressions for optimum order quantity and optimuim value of maximum inventory are obtained by minimizing the total system costs. The model is illustrated with a numerical example, including sensitivity analysis with respect to the backlogging parameter.     

A general model for EOQ inventory systems with partial backlogging and linear shortage costs

We present a mathematical model which generalises several known deterministic Economic Order Quantity (EOQ) inventory systems with partial backlogging. This inventory model considers purchasing cost, holding cost, shortage costs and replenishment cost. Shortage costs (backorder cost and lost sales cost) are both made up of a fixed cost and a variable cost which depends on the length of the waiting time for the next replenishment. The optimal policy is characterised through a sequential optimisation procedure. To illustrate the model, numerical examples and sensitivity results are given.     

A partial backlogging production-inventory lot-size model for deteriorating items with time-varying production and demand rate over a finite time horizon

In this article, I extend Balkhi ((2001), ‘On a Finite Horizon Production Lot Size Inventory Model for Deteriorating Items: An Optimal Solution’, European Journal of Operational Research, 132, 210–223), by considering a generalised mathematical production-inventory model for deteriorating items with partial backlogging. The demand, production and backlogging rates are assumed to be continuous and varying with time. The objective is to find the optimal production restarting and stopping time to keep the total relevant cost as low as possible. To ascertain the optimal solution exists, the conditions for the total relevant cost in the system which attains its global minimum are provided. In addition, based on the minimum total relevant cost, an alternative among the proposed four cases is also suggested. Finally, a numerical example and sensitivity analysis is illustrated and some management insights are presented.     

可延迟供货的冷轧生产库存问题之建模与优化

本文针对可延迟供货的冷轧生产系统,建立了以最小化库存成本、拖期惩罚和启动成本为目标的多阶段生产库存模型,模型中充分考虑了工序不允许停机的情况以及计划与调度之间的一致性问题.同时开发了基于变量分离的有效拉格朗日松弛求解算法,并使用120个基于实际生产数据的算例进行了仿真实验,计算结果显示该算法能够在合理的时间内得到高质量的解.     

Balancing stocks and backlogs with stochastic lead times: A special case

The paper gives compact, finite horizon and asymptotic results concerning an inventory system, that allows backlogging, with constant demand and costs but stochastic lead times, not necessarily i.i.d., under two special conditions. The special conditions are: (1) no crossovers of orders; (2) there are both shortage and stock build-up between any two consecutive orders. It is shown that the minimal total expected cost, namely, of holding inventory, shortages and replenishments, as well as the optimal replenishment times depend, among other parameters, only on the lead time variances as representatives of the stochastic component of the model. The results are direct extensions of the deterministic EOQ model and lend themselves to tractable sensitivity analysis. Further possible developments are discussed.     

An inventory model for deteriorating items with partial backlogging and permissible delay in payments

The paper deals with an inventory model with a varying rate of deterioration and partial backlogging rate under the condition of permissible delay in payments. The existing literature on the subject generally deal with situations where the payment of an order is made on the receipt of items by the inventory system and shortages are either completely backlogged or fully lost. In this paper, a varying deterioration rate of time and the condition of permissible delay in payments used in conjunction with the economic order quantity model are the focus of discussion. In addition, the shortages are neither completely backlogged nor completely lost assuming the backlogging rate to be inversely proportional to the waiting time for the next replenishment. Numerical examples are presented to illustrate the model.     

Optimal price and order size for a reseller under partial backordering

The problem of determining the optimal price and lot size for a reseller is considered in this paper. It is assumed that demand can be backlogged and that the selling price is constant within the inventory cycle. The backlogging phenomenon is modeled without using the backorder cost and the lost sale cost since these costs are not easy to estimate in practice. The case in which the selling price is fixed and therefore, demand is a known constant is also considered. Given the new way of modeling the backlogging phenomenon, the results for the case of constant demand are developed. Analysis is also presented for the reselling situation in which a nonperishable product is sold.Scope and purposePerishable products constitute a sizable component of inventories. A common question in a reselling situation involving a perishable (or a nonperishable) product is: What should be the size of the replenishment? If demand for the product is sensitive to price, then another question is: What should be the selling price? Although the ability to vary price within an inventory cycle is important, in many cases, the reseller may opt for a policy of constant selling price for administrative convenience. In this paper the pricing and/or lot sizing problem faced by a reseller is modeled assuming a general deterioration rate and a general demand function. The model allows for backlogging of demand. When a product is highly perishable, the reseller may need to backlog demand to contain costs due to deterioration. In this sense, perishability and backlogging are complementary conditions. Given that the problem entails revenue and costs, a natural objective function for the model is profit per period. The conventional approach to modeling the backlogging phenomenon requires the use of the backorder cost and the lost sale cost. These costs, however, are difficult to estimate in practice. A new approach is used in which customers are considered impatient. Hence the fraction of demand that gets backlogged at a given point in time is a decreasing function of waiting time. First the subproblem in which price is fixed is solved to determine the optimal inventory policy. The subproblem represents the important case in which the reseller has no flexibility to change the selling price. Then a procedure is developed for determining the optimal quantity and the selling price for the broader problem. The procedure can be implemented on a spreadsheet.     

The lot size-reorder level inventory system with customers impatience functions

In this paper, we study a continuous review inventory model with deterministic demand. The model allows shortages, which are partially backlogged. The backlogging is characterized using an approach in which customers are considered impatient. Total profit function is developed using three general costs: holding cost, order cost and shortage cost. Holding cost is based on average stocks and order cost is fixed per replenishment. In shortage cost, we include three significant costs: the unit backorder cost (depending on the shortage time), the goodwill cost (constant) and the opportunity cost. A general approach is presented to determine the economic lot size, the reorder level and the minimum total inventory cost. We consider two customers impatience functions to illustrate the application of the procedure. This paper extends several models studied by other authors.     

Analysing the effectiveness of vendor-managed inventory in a single-warehouse,multiple-retailer system

This paper considers a two-stage supply chain, consisting of a single warehouse and multiple retailers facing deterministic demands, under a vendor-managed inventory (VMI) policy. It presents a two-phase optimisation approach for coordinating the shipments in this VMI system. The first phase uses direct shipping from the supplier to all retailers to minimise the overall inventory costs. Then, in the second phase, the retailers are clustered using a construction heuristic in order to optimise the transportation costs while satisfying some additional restrictions. The improvement of the system's performance through coordinated VMI replenishments against the system with direct shipping only is shown and discussed in the comparative analysis section.     

Multi-item partial backlogging inventory models over random planninghorizon in random fuzzy environment

In this paper, some multi-item inventory models for deteriorating items are developed in a random planning horizon under inflation and time value money with space and budget constraints. The proposed models allow stock dependent consumption rate and partially backlogged shortages. Here the time horizon is a random variable with exponential distribution. The inventory parameters other than planning horizon are deterministic in one model and in the other, the deterioration and net value of the money are fuzzy, available budget and space are fuzzy and random fuzzy respectively. Fuzzy and random fuzzy constraints have been defuzzified using possibility and possibility–probability chance constraint techniques. The fuzzy objective function also has been defuzzified using possibility chance constraint against a goal. Both deterministic optimization problems are formulated for maximization of profit and solved using genetic algorithm (GA) and fuzzy simulation based genetic algorithm (FAGA). The models are illustrated with some numerical data. Results for different achievement levels are obtained and sensitivity analysis on expected profit function is also presented.Scope and purposeThe traditional inventory model considers the ideal case in which depletion of inventory is caused by a constant demand rate. However for more sale, inventory should be maintained at a higher level. Of course, this would result in higher holding or procurement cost, etc. Also, in many real situations, during a shortage period, the longer the waiting time is, the smaller the backlogging rate would be. For instance, for fashionable commodities and high-tech products with short product life cycle, the willingness for a customer to wait for backlogging diminishes with the length of the waiting time. Most of the classical inventory models did not take into account the effects of inflation and time value of money. But at present, the economic situation of most of the countries has been much deteriorated due to large scale inflation and consequent sharp decline in the purchasing power of money. So, it has not been possible to ignore the effects of inflation and time value of money any further. The purpose of this article is to maximize the expected profit of two inventory control systems in the random planning horizon.