供应链上游段VMI模式的共赢条件

选取上游层面VMI模式各参与者为研究对象.考虑实施上游层面VMI模式后,订货(配送)主动权的转移导致订货(配送)策略的不同,以及制造商对各零部件需求速率的不同导致其对各零部件的订货周期也不一致的情况.通过建立数学模型,对实施上游层面VMI模式前后各企业的经济效益进行比较,探讨实施VMI且制造商销售价格不变时,各供应商是否存在合理的销售价格涨幅区间,该区间的价格既能弥补供应商因管理制造商零部件库存多消耗的成本,也能使各制造商和供应商的经济效益都有所提高,实现共赢,为各企业更加长久的合作提供理论依据.     

Vendor-managed inventory: a review based on dimensions

Vendor-managed inventory (VMI) represents the methodology through which the upstream stage of a supply chain (vendor) takes responsibility for managing the inventories at the downstream stage (customer) based on previously agreed limits. VMI is another method by which supply chains can be managed, and, owing to centralised decision-making and constant information sharing, the benefits are much higher than in traditional supply chain case. However, there exists a lack of research that identifies the dimensions of VMI, benefits of VMI, methods, and levels used in the VMI environment. The focus of this paper is to explore the existing literature on VMI, to categorise it according to the criteria evaluated, and to present a systematic review. In this study, we have classified the review into three categories such as dimension-based, methodology-based, and level-based. From the thorough literature review, we have identified six dimensions of VMI: namely, inventory, transportation, manufacturing, general benefits, coordination/collaboration, and information sharing. In addition, there are, three methodological classifications: modelling, simulation, and case studies. Finally, we will consider the level-based classification. Based on the review, several recommendations that improve the performance of VMI are presented.     

基于VMI的医院供应管理

医院大部分药品及相关用品属于易逝品,针对该类产品的特点,将VMI(Vender Managed Inventory)方法引入到医院供应管理研究中,通过建立两级供应链库存定量模型(即供应商-医院关系模型),比较实施VMI方法前后,医院、供应商以及供应链总库存成本的变化情况.通过定量比较证实,实施VMI方法可以有效降低医院及供应链总库存成本,供应商的库存成本虽有所升高,但是可以通过转移支付方法,使供应商与医院达到利益均衡点,从而降低供应链总库存成本,获得pareto均衡.     

跨境VMI供货模式下生产-库存联合优化研究

研究基于跨境VMI(vendor managed inventory)供货模式下的生产-库存联合优化问题。以一个实际案例企业作为应用背景,比较了VMI供货模式和传统的供货模式在海运和空运2种运输方式下的不同特点及其对决策的影响。研究结果表明,对于案例企业而言,采用VMI供货模式的库存管理是可行的,考虑目前公司采用2种可选的运输模式,选择海运的总成本最低。通过对资金费用率、库存费用比率和缺货费用率进行灵敏度分析,探讨了不同环境变量对最优决策的影响。研究结果对跨境供应链多国生产型企业改善跨境物资采购和生产-库存决策有一定参考价值。     

VMI versus information sharing: an analysis under static uncertainty strategy with fill rate constraints

A vendor-managed inventory (VMI) relationship between a downstream retailer and an upstream vendor consists of two distinct components: (i) information sharing (IS) and (ii) a shift in decision-making responsibility. This study compares these two components of VMI in a two-stage serial supply chain based on the ‘static uncertainty’ strategy under dynamic and random demand with fill rate constraints. Numerical experiments are conducted using analytical models to identify the conditions where the incremental value of VMI over IS is significant. The results provide guidelines relevant to academia and supply chain practitioners in taking VMI adoption decision above and beyond IS according to their specific business environment.     

An analysis of the general benefits of a centralised VMI system based on the EOQ model

Within a vendor-managed inventory (VMI) agreement, the upstream supply chain member (the vendor) takes responsibility for managing the inventory of the downstream member (the customer) within specific levels previously agreed upon without the need of orders from the customer side to be placed. Therefore, the vendor can focus on optimising production efficiency and capacity planning, while the customer has to improve forecast accuracy. This paper analyses the benefits a VMI agreement could bring for a one-supplier, multiple-customer case through analysing two cases: a supply chain managed in a traditional manner and VMI when both the vendor and the customers belong to the same organisation. The analysis is based on the economic ordering quantity (EOQ) formula and its related total cost, and the novelty is captured by evaluating one vendor, multiple buyers, and multiple product situations. The modelling is done so as to capture the needs and factors which occur within the pharmaceutical industry and a numerical application will be executed with data from one of the main leaders within the pharmaceutical field.     

Comparing different coordination scenarios in a three-level supply chain system

The consignment stock (CS) policy, independently or coupled with vendor managed inventory (VMI), has been practised by businesses and shown to be profitable. It helps to reduce or eliminate out-of-stock instances caused by fluctuations in demand. CS brings several benefits to collaborating parties. Unlike the two-level supply chain models in the literature, this paper considers a three-level supply chain that consists of a supplier, a vendor and a buyer with CS policy agreements. The paper also examines four coordination scenarios (a combination of traditional and CS) in conjunction with a payment scheme between adjacent parties. Nine coordination cases (models) are provided. A sensitivity analysis is performed to study the effects of some parameters on the performance of the developed models. Most of the results showed that a combination of traditional and CS policies returned a higher total system profit.     

Vendor-managed inventory and the effect of channel power

We analyze decentralized supply chains that follow general continuous review (Q, R) inventory policies subject to vendor-managed inventory agreements where the supplier chooses the order quantity Q, and the retailer chooses the reorder point R. Within the VMI scenario, we explore the effect of divisions of channel power on supply chain and individual agent performance by examining different game theoretic models. Optimal policies and analytical results, including existence and uniqueness proofs for equilibrium solutions under VMI, are derived. Numerical results are provided to compare the effectiveness of VMI and to analyze different channel power relationships under a variety of environmental conditions. We find that VMI can result in considerable supply chain savings over traditional relationships and that the relative division of channel power can significantly effect the performance of VMI. Interestingly, we find that the greatest system benefits from VMI arise in asymmetric channel power relationships, but that individual agents lack the incentive to assume a leadership role.     

具有缺陷品的双渠道供应链库存优化策略

为研究双渠道供应链库存优化问题，考虑由一个网络零售商和一个传统零售商构成的缺陷品双渠道供应链系统，允许不同渠道零售商之间采用横向转运策略协调库存水平，引入渠道间消费者购买转移，运用马尔科夫链来描述零售商的库存状态，建立以库存成本最小为目标的数学模型，并运用遗传算法进行求解。通过对允许转运和不允许转运2种方案的对比，得出在分销缺陷产品的双渠道供应链中，双渠道间采取转运策略可以降低最优库存量和总成本；随着购买转移概率的增加和产品缺陷率的增加，转运策略带来的系统绩效均不断降低。     

短缺量拖后率与价格折扣相关变质品VMI模型

考虑短缺量拖后率与订货商给予顾客的价格折扣正线性相关,提出一种需求指数时变的变质物品供应商管理库存模型,研究了供应链最优库存策略。数值仿真和主要参数灵敏度分析表明,订货商在缺货期间向顾客提供价格折扣有利于降低丢单损失和系统库存总成本;当需求增长因子变化时,VMI系统应保持库存控制策略不变;当变质系数和拖后率上限变大时,VMI系统则应保持订货商补货次数和价格折扣不变,同时适当降低订货商服务水平。     

Vendor-managed inventory with consignment stock agreement for single vendor–single buyer under the emission-trading scheme

This paper presents a joint economic lot size (JELS) model for coordinated inventory replenishment decisions under the vendor-managed inventory (VMI) with consignment stock (CS) agreement and an emission-trading scheme. The paper assumes a single product that flows along a two-level supply chain system, with a single vendor and a single buyer. The total cost of the system is the performance measure, which is the sum of the vendor’s and the buyer’s total costs. The total cost includes the set-up and order costs, inventory holding costs, greenhouse gases (GHG) emissions tax and penalty costs. A mathematical model is proposed to determine: (1) the vendor’s production lot size quantity; (2) the number of shipments sent by the vendor to the buyer in a cycle; and (3) the production rate that minimises the total cost of the supply chain. Some numerical examples are carried out, as well as comparisons with the traditional JELS model for a classic two-level supply chain. Results show that the performance of the system is better when it is operated under a VMI with CS agreement, which is capable of reducing the traditional inventory holding costs and, for some values of given parameters, the GHG emissions tax and penalty costs.     

A supply chain model with vendor-managed inventory,consignment, and quality inspection errors

This paper considers the integration between quality control and production inventory control in supply chain management. Specifically, we study the effect of inspection errors on the costs incurred in a supply chain system with a single vendor and multiple buyers. In this system, the vendor enters into a vendor-managed inventory (VMI) and a consignment stock (CS) partnership with several buyers. We assume that the items made by the vendor are not in perfect quality, but they contain a given proportion of defective units. We also assume that quality inspection of these items by the buyers is subject to sampling errors. Three cases indicating to different levels of supply integration are considered: VMI–CS system, traditional system and integrated system. For each case, a mathematical model is formulated, an optimum solution is developed, and a numerical example is solved.     

A vendor-managed inventory scheme as a supply chain coordination mechanism

In this paper, we have considered a vendor-managed inventory (VMI) arrangement in a supply chain (SC), where the buyer imposes a penalty for shipments exceeding an upper limit. We have shown as how the industry practice of VMI under penalty can be used as a SC coordination mechanism. The vendor can influence the buyer to increase the batch size without making the buyer worse off. We also discuss how such a penalty scheme may be derived. Further, we have established the equivalence of VMI under deterministic demand with that of quantity discount models, thus highlighting the need to incorporate both cooperation and coordination perspectives while analysing SC collaboration mechanisms.     

Measure of the bullwhip effect considering the market competition between two retailers

In order to consider the market competition, a new supply chain with one supplier and two retailers is established in this paper. Two retailers employ different AR(1) demand processes, respectively, and an order-up-to inventory policy characterises the inventory decisions. The bullwhip effect in this supply chain is measured under the moving average forecasting technique. We investigate the effects of the lead time, the span of forecast, market competition and the consistency of demand volatility on the bullwhip effect using the algebraic analysis and numerical simulation. Conclusions indicate that different factors lead to the bullwhip effect following different patterns in the supply chain. Moreover, some suggestions are present to help managers to control parameters that yield the lower bullwhip effect.     

供应商管理库存的价格效应研究

通过建立数学模型,论证了VMI在供应链中收益的非负性;在此基础上还给出了供求均衡价格与订货成本比、库存成本比的函数关系,该公式说明当订货成本比与库存成本比相差比较大时,VMI可以有效降低均衡价格,否则均衡价格将会上升。     

考虑运输能力约束的VMI补货发货动态批量研究

考虑由一个供应商和多个零售商构成的VMI供应链,在供应商运输能力有限、可采用外包策略的情况下,研究了动态需求环境下供应链补货及发货批量策略问题.分析得出供应商最优补货及发货期结构满足"零库存补货"性质,进而利用动态规划方法提出一个多项式算法优化补货及发货策略,其计算复杂度为O(T3),且通过平衡各种成本,可得每个发货周...     

考虑随机市场需求和不同博弈地位的双渠道供应链策略分析

为研究供应链成员不同博弈地位下双渠道定价及随机库存问题,分别构建制造商主导、零售商主导及双方同等博弈地位的双渠道供应链博弈模型,考察随机市场需求对定价、库存及利润的影响,分析具有不同博弈地位的供应链策略差异,并通过数值仿真探讨最佳响应策略。结果表明,主导方凭借地位优势拥有更强的价格把控权及库存调配能力,获得更高收益;制造商主导型供应链具有更强的渠道整合能力,供应链的整体利润水平高于零售商主导型;同等博弈地位情形的博弈双方可根据共同市场信息及竞争对手策略更新自身策略,具有较低的库存风险,渠道定价越低,但双重边际效应降低了双方收益;市场需求波动越大,渠道定价、库存量及供应链利润均越大,此时主导方利润增幅大于追随者。     

考虑缺货成本的VMI利益分配

考虑缺货成本,从库存成本角度开展研究,通过对比实施VMI前后供应链库存成本模型,指出VMI短期内供应链收益来源于库存成本变化,且存在责任利益不一致的情况。针对供需双方不同地位,应用价格契约、斯坦科尔博格博弈模型与收益共享契约分别建立了零售商占优与供需双方地位平等情况下的利益分配模型,求解出零售商激励采购价格与收益共享系数的具体值,并采用算例进行分析。     

The role of spot market in a decentralised supply chain under random yield

We consider a decentralised supply chain with demand uncertainty, wherein a manufacturer sells a single product that consists of two components to the end consumer through an independent distributor. Assume that one component has a random yield, the manufacturer may rely on the spot market to replenish any shortage components after the random yield is realised. We identify the optimal product order, component production and replenishment decisions under two different situations. One is the traditional arrangement that the distributor decides the product procurement quantity and the manufacturer chooses the production quantity. The other is vendor-managed inventory (VMI) arrangement in which the manufacturer is responsible for both the order and the production decisions. The results show that the role of spot market can effectively offset the negative effects from production yield’s, market demand’s and component spot price’s variances. Consequently, the spot market leads to the cooperation between the manufacturer and the distributor, and improves the channel’s overall performance, in particular under the VMI arrangement when the wholesale price is sufficiently high.     

Revisiting rescheduling: MRP nervousness and the bullwhip effect

We study the material requirements planning (MRP) system nervousness problem from a dynamic, stochastic and economic perspective in a two-echelon supply chain under first-order auto-regressive demand. MRP nervousness is an effect where the future order forecasts, given to suppliers so that they may plan production and organise their affairs, exhibits extreme period-to-period variability. We develop a measure of nervousness that weights future forecast errors geometrically over time. Near-term forecast errors are weighted higher than distant forecast errors. Focusing on replenishment policies for high volume items, we investigate two methods of generating order call-offs and two methods of creating order forecasts. For order call-offs, we consider the traditional order-up-to (OUT) policy and the proportional OUT policy (POUT). For order forecasts, we study both minimum mean square error (MMSE) forecasts of the demand process and MMSE forecasts coupled with a procedure that accounts for the known future influence of the POUT policy. We show that when retailers use the POUT policy and account for its predictable future behaviour, they can reduce the bullwhip effect, supply chain inventory costs and the manufacturer’s MRP nervousness.