Abstract
We consider a liquid type of a deteriorating item which is packaged by an outside supplier and is delivered to final customers by a distributor. Customers arrive according to a Poisson process and ask for an integer number of packages. Unsatisfied demands are backordered. The inventory is reviewed continuously and replenished from an external supplier with a positive deterministic lead time following an (r, nQ) policy. The product in each package deteriorates continuously over time during transportation and storage. Therefore, the distributor cannot deliver exactly one unit of usable material in each package. We develop a model to determine the optimal inventory control parameters and the required size of a package to minimize expected average costs and illustrate the benefit of this method compared to a sequential approach based on an example from practice.
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Acknowledgements
The authors acknowledge the helpful comments of two anonymous reviewers. This research was conducted while the first author was a visiting Ph.D. student at the University of Vienna.
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Appendix
Appendix
In Model 2, α is a continuous decision variable and we investigate the convexity of C{α, r, Q) according to α for given r and Q.
For the penalty cost Cp, t B depends on α
We also know
According to C P from (15) the first derivative of C P is
We conclude that:
The second derivative is
Using , expression (A.2) becomes
It is obvious that expression (A.3) is positive, so C(α, r, Q) is convex in α for any given r and Q.
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Molana, S., Davoudpour, H. & Minner, S. An (r, nQ) inventory model for packaged deteriorating products with compound Poisson demand. J Oper Res Soc 63, 1499–1507 (2012). https://doi.org/10.1057/jors.2011.154
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DOI: https://doi.org/10.1057/jors.2011.154