Periodic Review Inventory Systems


Book Description

The focus of the work is twofold. First, it provides an introduction into fundamental structural and behavioral aspects of periodic review inventory systems. Second, it includes a comprehensive study on analytical and optimization aspects of a specific class of those systems. For the latter purpose, general solution methods for problems of inventory management in discrete time are described and developed along with highly specialized methods to solve very specific problems related to the model variants examined. The work is thus addressed to students and practitioners who seek a deeper understanding of managing inventories in discrete time as well as to software developers who require implementation aids on specific problems of inventory management.







Base Stock Policies for Periodic Review Inventory Systems


Book Description

We study two stochastic inventory systems. The first part deals with an (s, S) system system, and the second part with an ( R, T) system. In a (s, S) system, the inventory position of a product is reviewed regularly (every T periods), and, if it is found to be below a threshold s, an order is placed to bring the item's inventory position to the level S. In a (R, T) system, an order is placed every T periods to bring the inventory up to the base stock R; it is a special case of an (s, S) system, with s set at minus infinity.




Optimal Inventory Control Policy for Periodic-Review Inventory Systems with Inventory-Level-Dependent Demand


Book Description

We consider a setting in which inventory plays both promotional and service roles; that is, higher inventories not only improve service levels but also stimulate demand by serving as a promotional tool (e.g., as the result of advertising effect by the enhanced product visibility). Specifically, we study the periodic-review inventory systems in which the demand in each period is uncertain but increases with the inventory level. We investigate the multiperiod model with normal and expediting orders in each period, that is, any shortage will be met through emergency replenishment. Such a model takes the lost sales model as a special case. For the cases without and with fixed order costs, the optimal inventory replenishment policy is shown to be of the base-stock type and of the (s, S) type, respectively.




A Periodic Review Inventory System with S-Shaped Utility Function


Book Description

Prospect theory shows that human behavior in decision making can often be characterized by an S-shaped utility function. In this paper, we consider a periodic review inventory system with an exponential-type S-shaped utility function. The objective is to maximize the total expected utility over the planning horizon. We show that, for the single-period case without setup cost, a state-dependent order-up-to policy is optimal, to which it is not difficult to obtain the optimal order-up-to level. For the multi-period case without setup costs, we partially characterize the optimal policy when the demand distributions are log-concave, and present an iterative algorithm for computing the optimal policy. Numerical studies are conducted to illustrate the impact of parameters on the system performance and optimal policies. The results show that the ordering behavior of the inventory manager can be significantly different from those derived from the classical models. It is also shown that the approaches in this paper can be applied to both single-period and multi-period systems with setup costs for obtaining optimal policies.







An Optimal Expediting Policy for Periodic-Review Inventory Systems


Book Description

We analyze a periodic-review base-stock inventory system where outstanding orders can be expedited. Most inventory models assume that lead times are exogenously given, i.e., that orders arrive after a lead time that cannot be controlled by the inventory manager. However, in many situations inventory managers have the option to expedite open orders. We incorporate the expediting option into a periodic-review base-stock inventory model and solve the model optimally. We prove several structural properties of the model and show how the optimal solution can be computed efficiently. We numerically analyze the sensitivity of the inventory system with respect to the key parameters and quantify the benefit of order expediting using data from the service division of a global equipment manufacturer.