Strategic inventory in capacitated supply chain procurement

We study the strategic role of inventory in a sequential two‐period procurement setting, where the supplier's capacity in the first period is limited and the retailer has the option to hold inventory. We compare the equilibrium under a dynamic contract, where the decisions are made at the beginning of each period, and a commitment contract, where the decisions for both periods are made at the beginning of the first period. We show that there is a critical capacity level below which the outcomes under both types of contracts are identical. When the first period capacity is above the critical level, the retailer holds inventory in equilibrium and the inventory is carried due to purely strategic reasons; as capacity increases, so does the strategic role of inventory. The supplier always prefers lower capacity than the retailer, and the difference between supplier‐optimal and supply‐chain optimal capacities, and the corresponding profits, can be significant. Finally, we find that the retailer's flexibility to hold inventory is not always good for the participants or for the channel. Copyright © 2008 John Wiley & Sons, Ltd.     

基于零库存管理的供应商选择

基于建筑企业物资管理采用零库存的管理理念,提出了建筑企业供应商选择的基本指标,采用层次分析法分析了零库存条件下物资供应商的选择。并结合工程实例,建立AHP模型,介绍了在建筑企业零库存物资管理中如何进行供应商选择的方法。     

供应不确定下基于Supply-hub的供应商选择和库存协同决策

针对由供应商、Supply-hub和制造商组成的三级供应链的多产品供应商选择和库存协同问题,考虑供应商存在延迟交付风险、供应数量约束,以供应链运作成本最小为目标,构建整数规划模型。分析结果表明:在一定的条件下,总存在最优的供应商选择方案和库存策略;当供应商的延迟交付概率增加,供应链期望成本上涨;当供应商供应数量无限制时,减少最优订货批量可以弱化供应不确定性增加造成的影响;当供应商选择方案不变,订货提前期增加,供应链的运作成本以及最优订货批量不变;一种零部件提前期的变化不影响其他零部件的供应商选择和库存策略。     

A two-period newsvendor model for prepositioning with a post-disaster replenishment using Bayesian demand update

Humanitarian aid agencies usually resort to inventory prepositioning to mitigate the impact of disasters by sending emergency supplies to the affected area as quickly as possible. However, a lack of replenishment opportunity after a disaster can greatly hamper the effectiveness of the relief operation due to uncertainty in demand. In this paper, a prepositioning problem is formulated as a two-period newsvendor model where the response phase is divided into two periods. The model acknowledges the demand to be uncertain even after the disaster and utilises the Bayesian approach to revise the demand of the second period. Based on the revised demand, an order is placed at the beginning of the second period to be replenished instantaneously. A two-stage solution methodology is proposed to find the prepositioning quantity and post-disaster replenishment quantity, which minimise the total expected costs of relief operations. A numerical example is presented to demonstrate the solution methodology, and sensitivity analysis is performed to examine the effect of model parameters. The results highlight the indifferent characteristics shown by the replenishment quantity with the variation in model parameters.     

基于库存调剂的易逝品供应链合作利益分配问题探讨

本文将解决多人合作博弈问题的Shapley值方法用于解决两级易逝品供应链合作利益分配问题。考虑由一个供应商和两个零售商所组成的两级供应链模型,零售商与供应商不合作时,零售商根据供应商的批发价确定订货量,合作时共同决定库存,零售商之间的合作为共同决定订货量且通过库存调剂(转运)共享库存,三方合作可获最大利益,采用Shapley值法可合理分配合作利益,从而使合作更稳定。     

Optimal structure of joint inventory-pricing management with dual suppliers and different lead times

We consider a joint inventory-pricing control problem in a single-product, periodic-review, dual-supplier inventory system. The two suppliers have different lead times. One expedited supplier offers instantaneous replenishment, and one regular supplier requires an L-period lead time for delivery. The supply quantity is stochastic and the demand is price-dependent. For the expedited inventory replenishment, we characterize the optimal policy as a state-dependent almost-threshold policy by extending the stochastically linear in mid-point to a multidimensional setting. To investigate the optimal regular inventory replenishment and pricing policy, we propose the notions of partially stochastic translation (PST) and increasing partially stochastic translation (IPST), which help in obtaining the antimultimodularity preservation in dynamic programming problems. We provide properties, sufficient conditions, and examples for PST and IPST functions. By applying PST and IPST, we obtain the antimultimodularity of the profit functions. The antimultimodular profit functions ensure that the optimal regular ordering quantity and the optimal price are monotone in the current inventory level and outstanding order quantities. Moreover, we reveal that as the time interval increases, the effects of previous outstanding orders on the optimal regular ordering and pricing decisions are decreasing and increasing, respectively. PST and IPST also enable us to further characterize the optimal expedited ordering quantity as decreasing in the inventory level. However, the optimal expedited ordering quantity can be non-monotone with respect to the outstanding order quantities, as shown in the example.     

Joint decision of procurement lot-size,supplier selection,and carrier selection

The joint decision making of procurement lot-size, supplier selection, and carrier selection has potential to reduce buyer's purchasing expenditures. Furthermore, the total logistics cost can also come down through economies of scale in the purchasing and transportation costs, and reduction in supply chain disruptions such as rejections and late deliveries. We study a procurement setting in which a buyer needs to purchase a single product from a set of suppliers over finite discrete time periods to satisfy service level requirements. The suppliers offer all-unit quantity discounts, and transportation cost depends on carrier capacity as well as geographical location of suppliers. This paper proposes an integer linear programming model to simultaneously determine the timings of procurement, lot-sizes, suppliers and carriers to be chosen so as to incur the least total cost over the planning horizon. A numerical example is included to demonstrate the effectiveness of the proposed model in establishing tradeoffs among purchasing cost, transaction cost, and inventory holding cost. Sensitivity analysis has been carried out to understand the effects of the model parameters on the purchasing decisions and total cost. Managerial insights of this study serve as a reference for decision makers to develop effective procurement strategies.     

基于Mediator/Wrapper的VMI系统的研究

供应商管理库存（VMI）是一种新的供应链库存管理方法,通过应用VMI,可以提高企业的运作水平,降低供应商和生产商、零售商的成本.然而,在电子商务环境下,供应商与生产商或零售商是多对多的关系,VMI系统的数据间的通信变得十分庞大复杂,信息的管理也变得很困难.为此,本文提出使用Java和XML开发基于Mediator/Wrapper的VMI系统,通过Mediator构建一个以客户应用层、中介器层和数据源层三层VMI系统,使用XML作为中介器层的数据的标准以及客户应用层和中介器层的接口,并提供统一的描述数据的结构的框架,以便在Web上部署,同时Wrapper可以解决多个供应商和零售商之间的信息异构问题.     

基于供应链协调机制的物流成本优化能力分析

本文以一个供应商和一个采购商组成的二级供应链为例,建立同时考虑库存成本和运输成本的物流成本模型,比较分析传统供应链和供应商管理库存两种协调机制的物流成本优化能力。研究发现:在集中决策的情况下,两种协调机制的供应链物流成本是相同的;在分散决策的情况下,传统供应链的协调机制在采购商和供应商分别负担运输成本的两种情况下物流成本均不会优于供应商管理库存协调机制的物流成本;传统供应链在集中决策的情况下能够实现供应链物流成本的最优,在分散决策的情况下由供应商负担物流成本有利于物流成本的优化。     

阶跃型顾客需求下供应链系统恢复稳定能力研究

建立了由供应商、零售商和顾客构成的简单供应链的库存决策模型,证明了在顾客需求发生突变前库存是稳定的,需求突变后库存发生震荡,但经过一段时间后库存又趋向于新的稳定状态。计算了从库存发生震荡到库存重新恢复稳定所需要的时间,分析了影响库存恢复稳定时间的主要因素,利用Matlab软件仿真验证了计算结果,并提出了相关管理建议。     

Optimizing the credit term decisions in supply chain finance

We study a credit term determination problem in the context of a supplier-buyer supply chain. The supplier's credit term decision is simultaneously made with its production and inventory decisions, and most importantly, it is impacted by the buyer's order quantity. We present a new game-theoretic framework to model this problem, which captures the interaction between the supplier's credit term decision and the buyer's order decision in a multi-period setting. An exact method based on nonlinear programming is implemented to obtain the optimal solutions. We apply our methodologies on a real world case. The computational results show that our approach significantly outperforms the heuristics with fixed credit terms, and either a short or a long credit term can be sub-optimal for the supplier in profitability. Our work offers the first data-driven model and solution approach that assists purchasing and supply managers to make optimal dynamic credit term decision in conjunction with production, ordering and inventory decisions in a game-theoretic setting.     

基于Arena的随机需求和随机提前期二级库存仿真优化

讨论了由一个供应商和多个经销商组成的二级库存优化问题,该系统中每个经销商的客户需求以及供应商和经销商的订货提前期都是随机的,供应商和每个经销商都采用(T,s,S)混合策略进行库存管理。首先建立了该二级库存系统优化问题的数学模型,然后设计了解决该问题的仿真流程并基于仿真软件Arena建立了仿真模型,通过对由一个供应商和三个经销商所组成的二级库存系统的仿真实验表明,利用计算机仿真方法能够很好地解决随机需求和随机提前期的二级库存系统优化问题,其所得结果更贴近实际系统。     

Supply chain decisions and coordination in the presence of an imperfect spot market

This study considers a supply chain consisting of a commodity supplier and a final product manufacturer with uncertain demand. In addition to purchasing from the supplier through a forward contract, the manufacturer can adjust their inventory by trading the commodity in an online spot market after observing the actual demand. However, the spot market is imperfect in that transactions cannot be certainly realized and come with additional transaction costs. Furthermore, the spot price is volatile such that overly relying on the spot market is unwise. To investigate how the spot market affects the decisions and coordination in a supply chain, we develop a game-theoretical model incorporating spot trading. We derive the optimal ordering decision in a centralized supply chain, as well as the supplier's and manufacturer's equilibrium pricing and ordering decisions in a decentralized supply chain. The impact of the imperfect spot market on the optimal decisions and profits is analyzed. This study also demonstrates how the supply chain can be coordinated in the presence of an imperfect spot market. Finally, a numerical analysis is performed to examine the analytical results. Our results indicate that the spot market can generally improve the performance of the centralized supply chain and benefit the manufacturer in the decentralized one. However, it can be detrimental to the supplier. The supply chain can be coordinated by a revenue-sharing contract, and both parties' profits can be improved. Our findings suggest that the manufacturer could take advantage of the spot market, and the supplier should attempt to integrate or coordinate the supply chain to share the benefits of spot trading.     

长尾市场网络销售商的订单履行渠道选择模型

研究传统市场和长尾市场条件下,网络零售商保有库存策略和直运策略的选择模型。建立了单周期动态仿真模型,进行了算例仿真,测算了市场竞争、供应商折扣、零售商订购策略和消费者对网络销售方式的接受程度等影响因素对网络零售商总利润的影响。结果表明,在缺乏定价权的实际条件下,网络零售商要获得更高的销售利润,需要增加产品品类、争取更大的价格折扣、采购合适数量的产品、选择合适的订单履行渠道。在未来的长尾市场中,产品品类更多、竞争更激烈、消费者选择产品的视野更开阔,直运方式将代替保有库存方式成为许多网络零售商的主流订单履行方式。     

“牛鞭效应”下的供应链库存管理研究

为发挥库存在企业的运作过程中的作用。改善客户服务水平,在库存位置接近客户时,满足较高的客户服务要求。文章在讨论供应链库存管理中牛鞭效应的基础上,主要研究供应链库存管理办法,提出了供应商的库存管理、联合库存管理和利用第三方物流供应商来管理库存三种方法。使得适当的库存存在不仅保证销售活动的顺利进行,而且提高了实际销售量,有助于降低采购和运输成本,产生一定的经济效益。     

Rationality in supplier selection decisions: The effect of the buyer's national task environment

Our study sheds light on two fundamental questions in supply management: First, does adherence to highly rational decision processes help buyers make better supplier selection decisions? Second, is the influence of procedural rationality on decision effectiveness moderated by buyers’ (differently dynamic) task environments? We empirically test these questions using a sample of 150 supplier selection decisions taken in China and 150 decisions taken in Germany, countries that expose buyers to dynamic decision environments and stable decision environments, respectively. Our findings suggest that the influence of decision process rationality is stable across decision makers’ task environments. Both in China and in Germany, such process rationality is positively related with higher decision quality, and no significant differences in relationship strengths emerge between the two country samples.     

零库存趋势下连锁超市业物流配送系统新探

物流配送系统是连锁超市业的生命线。传统配送模式主要有供应商直通、连锁超市业自营配送以及第三方物流供应三种模式。零库存发展的趋势给传统的配送模式提出了新的挑战。文中以ABC分类法为指导思想,实现零库存为目标,对连锁超市业配送模式提出了新的解析。初步形成了A类商品供应商直通,B类商品连锁超市自营配送,以及C类商品第三方物流企业供应的三位一体模式。     

A pragmatic decision model for inventory management with heterogeneous suppliers

For enterprises, it is imperative that the trade-off between the cost of inventory and risk implications is managed in the most efficient manner. To explore this, we use the common example of a wholesaler operating in an environment where suppliers demonstrate heterogeneous reliability. The wholesaler has partial orders with dual suppliers and uses lateral transshipments. While supplier reliability is a key concern in inventory management, reliable suppliers are more expensive and investment in strategic approaches that improve supplier performance carries a high cost. Here we consider the operational strategy of dual sourcing with reliable and unreliable suppliers and model the total inventory cost where the likely scenario lead-time of the unreliable suppliers extends beyond the scheduling period. We then develop a Customized Integer Programming Optimization Model to determine the optimum size of partial orders with multiple suppliers. In addition to the objective of total cost optimization, this study takes into account the volatility of the cost associated with the uncertainty of an inventory system.     

VMI策略在旭电库存管理中的应用

首先研究了成功实施VMI的条件,如VMI协议、实施双方的VMI流程及对接技术、实施VMI的信息技术基础、VMI HUB技术以及运行模式的选择。然后,进行了实施前对供应商的培训及VMI实施描述,最后阐述了实施VMI后对旭电库存管理带来的好处。     

改进的库容有限多品种联合订货库存问题研究

在传统的库容有限多品种联合订货库存模型的基础上建立库容有限多个供货商(包括单一供货商)多品种联合订货的库存模型,并给出其算法的步骤和算例。证明改进的多品种订货的库存模型要优于传统的,品种定货库存模型。