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Integrated lot sizing and production scheduling formulations: an application in a refractory cement industry

Abstract

This work presents an integrated lot sizing and scheduling problem for a large refractory cement manufacturer. Three mathematical formulations were addressed: two already presented in the literature, and one proposed as an alternative to the existing ones. This study aims to compare these formulations with respect to their performance and applicability as a decision support tool. One of these formulations uses continuous variables, whereas the others are based on time-indexed variables. These mathematical models address the specific concept of how variables and parameters are defined, requiring assumptions and particular settings to suit the real problem. In order to consider the different aspects of the practical situation, several instances were generated from uniform distributions based on real information. Extensive computational tests were run and, based on the results, the formulations were evaluated as a decision support tool and their efficiencies were compared.

Keywords:
Scheduling; Lot sizing; Production planning and control; Mathematical programming formulations

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