A Capacitated Multi‐echelon Inventory Placement Model under Lead Time Constraints

We develop an inventory placement model in the context of general multi‐echelon supply chains where the delivery lead time promised to the customer must be respected. The delivery lead time is calculated based on the available stocks of the different input and output products in the different facilities and takes into account the purchasing lead times, the manufacturing lead times, and the transportation lead times. We assume finite manufacturing capacities and consider the interactions of manufacturing orders between time periods. Each facility manages the stocks of its input and output products. The size of customer orders and their arrival dates and due dates are assumed to be known as in many B2B situations. We perform extensive computational experiments to derive managerial insights. We also derive analytical insights regarding the manufacturing capacities to be installed and the impacts of the frequency of orders on the system cost.     

Dynamic Pricing and Inventory Management with Regular and Expedited Supplies

We consider a periodic‐review inventory system with regular and expedited supply modes. The expedited supply is faster than the regular supply but incurs a higher cost. Demand for the product in each period is random and sensitive to its selling price. The firm determines its order quantity from each supply in each period as well as its selling price to maximize the expected total discounted profit over a finite or an infinite planning horizon. We show that, in each period if it is optimal to order from both supplies, the optimal inventory policy is determined by two state‐independent thresholds, one for each supply mode, and a list price is set for the product; if only the regular supply is used, the optimal policy is a state‐dependent base‐stock policy, that is, the optimal base‐stock level depends on the starting inventory level, and the optimal selling price is a markdown price that decreases with the starting inventory level. We further study the operational impact of such supply diversification and show that it increases the firm's expected profit, reduces the optimal safety‐stock levels, and lowers the optimal selling price. Thus that diversification is beneficial to both the firm and its customers. Building upon these results, we conduct a numerical study to assess and compare the respective benefit of dynamic pricing and supply diversification.     

含交付时间不确定性的供应链协调策略研究

分析含有交付时间不确定性的季节性供应链管理问题.如果在供应链中共享供应商的交付时间不确定性信息,零售商可以调整订货量,减少销售损失,就有可能提高供应链的整体利润.分析指出,当交付时间不确定性程度大时,信息共享能提高改进供应链绩效的可能性,但不一定能提高供应链的整体绩效,因而,仅仅采用信息共享有应用价值,但有一定的局限性.进一步分析发现,存在能协调这种含有交付时间不确定性供应链策略,能使供应链达到整体绩效最大化,并且对供应链的利润进行分配,协调策略能有效地弥补信息共享的局限性.     

我国发展高端物流的必要性、问题及政策思路

高端物流是近年来在我国物流领域中逐步受到重视的物流模式。文章通过引入高端物流概念,分析其区别于中低端物流的特性,明确高端物流的定位,结合我国现阶段各方面的发展趋势,阐述当前发展高端物流的必要性,探讨发展过程中存在的问题,提出相应的政策建议和思路。     

供应链提前期供需联合优化库存模型研究

本文研究由生产商和客户组成的二级供应链库存联合优化问题, 假设提前期服从均匀分布, 提前期订货受生产商的生产行为和客户的订货行为的制约, 建立了以库存成本为目标函数的供应链提前期供需库存模型, 提出了联合优化解决方案, 证明了目标函数在最优订货量和最优订货次数处存在最小目标值。在此基础上, 分析了提前期对供应链库存联合优化决策的影响。数据分析表明, 联合优化决策方法的库存成本曲线始终在分散决策优化方法的成本曲线的下方, 因此联合决策方法是非常有效的。     

Sample Timing and Mathematical Considerations for Modeling Breath Elimination of Volatile Organic Compounds

Real-world exposure measurements are a necessary ingredient for subsequent detailed study of the risks from an environmental pollutant. For volatile organic compounds, researchers are applying exhaled breath analysis and the time dependence of concentrations as a noninvasive indicator of exposure, dose, and blood levels. To optimize the acquisition of such data, samples must be collected in a time frame suited to the needs of the mathematical model, within physical limitations of the equipment and subjects, and within logistical constraints. Additionally, one must consider the impact of measurement error on the eventual extraction of biologically and physiologically relevant parameters. Given a particular mathematical model for the elimination kinetics (in this case a very simple pharmacokinetic model based upon a multitenn exponential decay function that has been shown to fit real-world data extremely well), we investigated the effects on synthetic data caused by sample timing, random measurement error, and number of terms included in the model. This information generated a series of conditions for collecting samples and performing analyses dependent upon the eventual informational needs, and it provided an estimate of error associated with various choices and compromises. Though the work was geared specifically toward breath sampling, it is equally applicable to direct blood measurements in optimizing sampling strategy and improving the exposure assessment process.     

供应物流利益分配机制研究

以单供应商-单制造商-多个第三方物流企业组成的供应物流外包系统为对象进行研究,对直接外包模式和领导物流合作伙伴(LLP)模式下三方企业的利益分配问题进行讨论.建立多委托人-多代理人的成本整合模型并求解,比较分析了在直接外包模式与LLP模式下三方企业的成本分摊与利益分配情况.研究结果揭示:1)LLP模式与直接外包模式相比...     

鱼粉中掺入血粉、豆饼的鉴定

本次实验在鱼粉中按不同比例掺入血粉、豆饼 ,使其达到粗蛋白在掺假前后基本一致。根据国家标准的饲料测定方法 ,研究掺假前后鱼粉的理化指标变化及定性检测和显微镜检 ,从而为鱼粉中掺假物质的检测建立一种科学的方法     

The Manufacturer's Incentive to Reduce Lead Times

Although, ceteris paribus, reducing lead times may be desirable from an overall system perspective, an upstream party (e.g., a manufacturer) may have strong disincentives to offer shorter lead times, even if this came at no cost. We consider a setting in which the downstream party has the ability to exert a costly effort to increase demand (e.g., through sales promotions, advertising, etc.) during the selling season, and compare two situations: one where there is zero lead time (i.e., all demand can be satisfied after observing the demand realization), and one where orders need to be made before demand is realized. We identify two interacting effects that may inhibit shorter lead times. A so‐called “safety stock effect” can be observed when a lower risk of stocking out under short lead times induces the downstream party to alter her order quantity. A second effect, termed as “effort effect,” arises if shorter lead times impact the downstream party's optimal sales effort, and, as a consequence, lead to different order quantities. We provide a formal characterization of both effects, insight into how these effects interact, and show under which conditions the manufacturer has an incentive to offer shorter lead times.