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Hybrid time slots sequencing model for a class of scheduling problems
Author(s) -
Castro Pedro M.,
Zeballos Luis J.,
Méndez Carlos A.
Publication year - 2012
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.12609
Subject(s) - scheduling (production processes) , computer science , wafer fabrication , mathematical optimization , job shop scheduling , heuristic , context (archaeology) , distributed computing , wafer , engineering , mathematics , artificial intelligence , schedule , electrical engineering , operating system , paleontology , biology
This article presents a new model for the short‐term scheduling of multistage batch plants with a single unit per stage, mixed storage policies, and multiple shared resources for moving orders between stages. Automated wet‐etching stations for wafer fabrication in semiconductor plants provide the industrial context. The uncommon feature of the continuous‐time model is that it relies on time grids, as well as on global precedence sequencing variables, to find the optimal solution to the problem. Through the solution of a few test cases taken from the literature, we show that new model performs significantly better than a pure sequencing formulation and better than a closely related hybrid model with slightly different sequencing variables. We also propose a new efficient heuristic procedure for extending the range of problems that can effectively be solved, which essentially solves relaxed and constrained versions of the full‐space model. © 2011 American Institute of Chemical Engineers AIChE J, 2012