We generalize the guaranteed-service (GS) model for multi-echelon safety stock placement to include capacity constraints. We first develop an extension of the single-stage base-stock model to include a capacity constraint. We then use this result to model a multi-stage system with a base-stock operating policy. We establish that we can adapt the existing algorithms for the unconstrained case to...

We study the optimal policy for a serial inventory system under periodic review when excess demand at the retailer (i.e., the most downstream stage) is lost. We focus on “high service level environments” (i.e., systems where the cost of a lost sale is high compared to inventory holding costs). These environments are typical of products whose margins are high relative to their holding costs. Whe...

We present a periodic review inventory model with multiple delivery modes and demand forecast updates. We generalize the notion of the base-stock policy for inventory system with multiple delivery modes. While base-stock policies are optimal for one or two consecutive delivery modes, it is not so otherwise. For multiple consecutive delivery modes, we show that only the fastest two modes have op...

We consider a single item assembled from two components. One of the components has a long leadtime, high holding cost and short review period as compared to the other one. We assume that net stocks are reviewed periodically, customer demand is stochastic and unsatisfied demand is back ordered. We analyze the system under two different policies and show how to determine the policy parameters min...

This paper analyzes a series inventory system with stationary costs and stochastic demand over an infinite horizon. A distinctive feature is that demand can be negative, representing returns from customers, as well as zero or positive. We observe that, as in a system with nonnegative demand, a stationary echelon base-stock policy is optimal here. However, the steadystate behavior of the system ...

The project work presented in this thesis has proposed solutions related to the control of production and work-in-process inventory in a multi-item multi-stage manufacturing system. A suitable base-stock inventory control policy is recommended to ensure that the desired service levels are maintained between production stages and for the final customers. Concept of coupling the production lines ...

We consider a spare parts stock point that serves an installed base of machines. Each machine contains the same critical component, whose degradation behavior is described by a Markov process. We consider condition based spare parts supply, and show that an optimal, condition based inventory policy is 20% more efficient on average than a standard, state-independent base stock policy. We further...

We consider a two-stage production-inventory system with demand at the downstream stage and returns at each stage. We characterize the structure of the optimal policy which is a complex state-dependent Base-stock policy. We also investigate four classes of policies : Fixed buffer, Base-stock echelon, Kanban and Half-optimal. We compare the performances of these policies and exhibit that the max...