Production-inventory control policy under warm/cold state-dependent fixed costs and stochastic demand

Partial characterization and heuristics

Ozgun Caliskan Demirag, Youhua Frank Chen, Yi Yang

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The motivation for our study comes from some production and inventory systems in which ordering/producing quantities that exceed certain thresholds in a given period might eliminate some setup activities in the next period. Many examples of such systems have been discussed in prior research but the analysis has been limited to production settings under deterministic demand. In this paper, we consider a periodic-review production-inventory model under stochastic demand and incorporate the following fixed-cost structure into our analysis. When the order quantity in a given period exceeds a specified threshold value, the system is assumed to be in a "warm" state and no fixed cost is incurred in the next period regardless of the order quantity; otherwise the system state is considered "cold" and a positive fixed cost is required to place an order. Assuming that the unsatisfied demand is lost, we develop a dynamic programming formulation of the problem and utilize the concepts of quasi-K-convexity and non-K-decreasing to show some structural results on the optimal cost-to-go functions. This analysis enables us to derive a partial characterization of the optimal policy under the assumption that the demands follow a Pólya or uniform distribution. The optimal policy is defined over multiple decision regions for each system state. We develop heuristic policies that are aimed to address the partially characterized decisions, simplify the ordering policy, and save computational efforts in implementation. The numerical experiments conducted on a large set of test instances including uniform, normal and Poisson demand distributions show that a heuristic policy that is inspired by the optimal policy is able to find the optimal solution in almost all instances, and that a so-called generalized base-stock policy provides quite satisfactory results under reasonable computational efforts. We use our numerical examples to generate insights on the impact of problem parameters. Finally, we extend our analysis into the infinite horizon setting and show that the structure of the optimal policy remains similar.

Original languageEnglish (US)
Pages (from-to)531-556
Number of pages26
JournalAnnals of Operations Research
Volume208
Issue number1
DOIs
StatePublished - Jan 1 2013

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Inventory control
Heuristics
Stochastic demand
Optimal policy
Fixed costs
Production-inventory
Order quantity
Infinite horizon
Inventory systems
Costs
Optimal solution
Base-stock policy
Periodic review
Convexity
Ordering policy
Inventory model
Cost structure
Dynamic programming
Numerical experiment

All Science Journal Classification (ASJC) codes

  • Decision Sciences(all)
  • Management Science and Operations Research

Cite this

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title = "Production-inventory control policy under warm/cold state-dependent fixed costs and stochastic demand: Partial characterization and heuristics",
abstract = "The motivation for our study comes from some production and inventory systems in which ordering/producing quantities that exceed certain thresholds in a given period might eliminate some setup activities in the next period. Many examples of such systems have been discussed in prior research but the analysis has been limited to production settings under deterministic demand. In this paper, we consider a periodic-review production-inventory model under stochastic demand and incorporate the following fixed-cost structure into our analysis. When the order quantity in a given period exceeds a specified threshold value, the system is assumed to be in a {"}warm{"} state and no fixed cost is incurred in the next period regardless of the order quantity; otherwise the system state is considered {"}cold{"} and a positive fixed cost is required to place an order. Assuming that the unsatisfied demand is lost, we develop a dynamic programming formulation of the problem and utilize the concepts of quasi-K-convexity and non-K-decreasing to show some structural results on the optimal cost-to-go functions. This analysis enables us to derive a partial characterization of the optimal policy under the assumption that the demands follow a P{\'o}lya or uniform distribution. The optimal policy is defined over multiple decision regions for each system state. We develop heuristic policies that are aimed to address the partially characterized decisions, simplify the ordering policy, and save computational efforts in implementation. The numerical experiments conducted on a large set of test instances including uniform, normal and Poisson demand distributions show that a heuristic policy that is inspired by the optimal policy is able to find the optimal solution in almost all instances, and that a so-called generalized base-stock policy provides quite satisfactory results under reasonable computational efforts. We use our numerical examples to generate insights on the impact of problem parameters. Finally, we extend our analysis into the infinite horizon setting and show that the structure of the optimal policy remains similar.",
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Production-inventory control policy under warm/cold state-dependent fixed costs and stochastic demand : Partial characterization and heuristics. / Caliskan Demirag, Ozgun; Chen, Youhua Frank; Yang, Yi.

In: Annals of Operations Research, Vol. 208, No. 1, 01.01.2013, p. 531-556.

Research output: Contribution to journalArticle

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