物流与供应链管理InventoryManagementandRiskPooling.pptVIP

Inventory Management, Supply Contracts and Risk Pooling 沈厚才 博士(Dr. Houcai SHEN) 南京大学 hcshen@ /shizi/gerenhomepage/shenhc.htm Outline of the Presentation Introduction to Inventory Management The Effect of Demand Uncertainty (s,S) Policy Supply Contracts Risk Pooling Centralized vs. Decentralized Systems Practical Issues in Inventory Management Inventory Where do we hold inventory? Suppliers and manufacturers warehouses and distribution centers retailers Types of Inventory WIP raw materials finished goods Why do we hold inventory? Economies of scale Uncertainty in supply and demand Goals: Reduce Cost, Improve Service By effectively managing inventory: Xerox eliminated $700 million inventory from its supply chain Wal-Mart became the largest retail company utilizing efficient inventory management GM has reduced parts inventory and transportation costs by 26% annually Goals: Reduce Cost, Improve Service By not managing inventory successfully In 1994, “IBM continues to struggle with shortages in their ThinkPad line” (WSJ, Oct 7, 1994) In 1993, “Liz Claiborne said its unexpected earning decline is the consequence of higher than anticipated excess inventory” (WSJ, July 15, 1993) In 1993, “Dell Computers predicts a loss; Stock plunges. Dell acknowledged that the company was sharply off in its forecast of demand, resulting in inventory write downs” (WSJ, August 1993) Understanding Inventory The inventory policy is affected by: Demand Characteristics Lead Time Number of Products Objectives Service level Minimize costs Cost Structure Cost Structure Order costs Fixed Variable Holding Costs Insurance Maintenance and Handling Taxes Opportunity Costs Obsolescence 经济批量的定货模型 基本假设 经济批量定货的特点 最佳定货策略是在库存保管成本与订货固定成本之间权衡 保管成本（HQ/2）= 固定成本（KD/Q） 总库存成本对订货批量的变动不敏感 在订货扁离经济批量定货的80%到120%, 误差3% The Effect of Demand Uncertainty Most companies treat the world as if it were predictable: Production and inventory planning are based on forecasts of demand made far in advance of t