A binary coding genetic algorithm for multi-purpose process scheduling: A case study

This paper presents a novel genetic algorithm (GA) for the scheduling of a typical multi-purpose batch plant with a network structure. Multi-purpose process scheduling is more difficult to deal with compared to single-stage or multi-stage process scheduling. A large amount of literature on this problem has been published and nearly all of the authors used mathematical programming (MP) methods for solution. In the MP methods, a huge number of binary variables, as well as numerous constraints to consider mass balance and sequencing of batches in space/time dimensions, are needed for the large-size problem, which leads to very long computational time. In the proposed GA, only a small part of the binary variables are selected to code into binary chromosomes, which is realized through the identification of crucial products/tasks/units. Due to the logical heuristics utilized to decode a chromosome into a schedule, only the feasible solution space is searched. Our genetic algorithm has first been devised with particular crossover for makespan minimization and then adjusted for production maximization. (C) 2010 Elsevier Ltd. All rights reserved