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We examine a possibly capacitated, periodically reviewed, single-stage inventory system where replenishment can be obtained either through a regular fixed lead time channel, or, for a premium, via a channel with a smaller fixed lead time. We consider the case when the unsatisfied demands are backordered over an infinite horizon, introducing the easily implementable, yet informationally rich dual-index policy. We show very general separability results for the optimal parameter values, providing a simulation-based optimization procedure that exploits these separability properties to calculate the optimal inventory parameters within seconds. We explore the performance of the dual-index policy under stationary demands as well as capacitated production environments, demonstrating when the dual-sourcing option is most valuable. We find that the optimal dual-index policy mimics the behavior of the complex, globally optimal state-dependent policy found via dynamic programming: the dual-index policy is nearly optimal (within 1% or 2%) for the majority of cases, and significantly outperforms single sourcing (up to 50% better). Our results on optimal dual-index parameters are generic, extending to a variety of complex and realistic scenarios such as nonstationary demand, random yields, demand spikes, and supply disruptions.
inventory/production, infinite horizon, policies, review/lead times, dual index, dual supply, uncertainty, stochastic
Veeraraghavan, S. K., & Scheller-Wolf, A. (2008). Now or Later: A Simple Policy for Effective Dual Sourcing in Capacitated Systems. Operations Research, 56 (4), 850-864. http://dx.doi.org/10.1287/opre.1080.0552
Date Posted: 27 November 2017
This document has been peer reviewed.