Valuing time in supply chains: Establishing limits of time-based competition

Over the past two decades the growth in international trade and the offshore migration of US manufacturing have created global supply chains with longer lead-times and slower response. This suggests that traditional supply chains have encountered limits to time-based competition in which the cost of faster replenishment exceeds the benefits. This paper explores and quantifies those limits to time-based competition in make-to-stock supply chains for functional products (products with stable demand over relatively long life cycles).     

An inventory and order admission control policy for production systems with two customer classes

In this paper we examine a Markovian single-stage system producing a single item to satisfy demand of two different customer classes. A simple threshold type heuristic policy is proposed for the joint control of inventories and backorders. Explicit forms of the steady-state probabilities under this policy are derived and used to assess the average profit rate of the system and determine the optimal control parameters. Certain properties of the average profit rate are established and used to develop computationally efficient algorithms for finding the optimal control parameter values. Numerical results show that the proposed policy is a very good approximation of the optimal policy and outperforms other commonly used policies.     

STRATEGIC INVENTORY OPTIMIZATION

A company's inventory metrics are often viewed as critical indicators of its supply chain performance although inventory costs are only a fraction of total supply chain costs comprised of supplier, manufacturing, transportation, and warehousing costs, as well as inventory costs. Moreover, inventories across the supply chain are dependent on acquisition and distribution decisions. We discuss how simulation and optimization models can be combined to integrate analysis of inventory and supply chain network design decisions in performing a total cost analysis. An application of the models to plans for distributing retail products to an expanding network of stores is reviewed.     

A serial mixed produce-to-order and produce-in-advance inventory model with multiple retailers

We formulate a general mixed produce-to-order and produce-in-advance inventory model having multiple stocking echelons and multiple retailers. We show that the problem to find an optimal inventory policy for such a model with a uniform or a normal demand distribution can be reduced to a general constrained optimization problem.     

Optimal economic ordering policy with deteriorating items under different supplier trade credits for finite horizon case

This paper develops and solves a general finite horizon trade credit economic ordering policy for an inventory model with deteriorating items under inflation and time value of money when shortages are not allowed. The time horizon is divided into different cycles each of which has its own demand rate and its own trade credit period offered from the supplier to his retailer so that the retailer should pay his supplier before or after the end of the permissible trade credit of that cycle. Up to the end of the trade credit of a cycle, the retailer is free of charge, but he is charged on an interest for those items not being sold before this end. The retailer can also earn the interest of the money from the generated sales revenue in any cycle by depositing such revenue into an interest bearing account. The objective of the retailer is then to minimize his net total relevant costs. A closed form of this net total cost is derived and the resulting model is solved. Then rigorous mathematical methods are used to show that, under some seemingly possible conditions, there exist a unique vector of the relevant decision variables that solve the underlying inventory system. A numerical example which shows the applicability of the theoretical results is given.     

A distribution-free newsvendor model with balking and lost sales penalty

In this paper, we extend the classical single period newsvendor model in an environment of customer balking, which occurs when customers are reluctant to buy a product if its available inventory falls below a threshold level. Since failure to make a sale usually results in a cost penalty, in addition to the opportunity cost of lost sales, we incorporate such costs in our model. Furthermore, we extend our model to include fixed ordering costs. Our analysis is based on the assumption that only the mean and the variance of the distribution of demand are known, without assuming any specific distributional form. We illustrate the concepts developed here through simple numerical examples and demonstrate the effectiveness of our approach by solving a set of 1000 randomly generated test problems.     

The MPS parameterization under lead time uncertainty

The supply planning of assembly systems under lead times uncertainty is studied. The used criteria is the sum of the average holding cost for the components, the average backlogging cost for the finished product, and the setup cost. The decision variables are the planned lead times of components and the periodic ordering quantity. A new generalized Newsboy model gives the optimal solution under the assumption that the lead times of the different types of components follow the same distribution probability, and that the holding costs per period of the ordered quantities are the same.     

关于器材保障供应链管理库存控制

结合器材保障供应链中存在的牛鞭效应，就实施供应链管理的一个重要方面——库存控制问题进行探讨，提出了实行供应商管理库存的库存控制策略，并就其实施作了初步研究。     

电子产品的回收物流库存控制研究

研究了价值随时间迅速衰减的电子类产品的回收物流库存控制系统。回收物流系统中既包含一般制造的新产品,也包含回收再制造的产品,而且该类产品的更新换代很快,产品生命周期很短。运用最优库存理论,推导出了在不同控制方式下的EOQ模型,以确定最优生产批量和最优再造批量。