American Journal of Applied Sciences

Three Algorithms for Flexible Flow-shop Scheduling

Tzung-Pei Hong, Pei-Ying Huang, Gwoboa Horng and Chan-Lon Wang

DOI : 10.3844/ajassp.2007.887.895

American Journal of Applied Sciences

Volume 4, Issue 11

Pages 887-895

Abstract

Scheduling is an important process widely used in manufacturing, production, management, computer science, and so on. Appropriate scheduling can reduce material handling costs and time. Finding good schedules for given sets of jobs can thus help factory supervisors effectively control job flows and provide solutions for job sequencing. In simple flow shop problems, each machine operation center includes just one machine. If at least one machine center includes more than one machine, the scheduling problem becomes a flexible flow-shop problem. Flexible flow shops are thus generalization of simple flow shops. In this paper, we propose three algorithms to solve flexible flow-shop problems of more than two machine centers. The first one extends Sriskandarajah and Sethi’s method by combining both the LPT and the search-and-prune approaches to get a nearly optimal makespan. It is suitable for a medium-sized number of jobs. The second one is an optimal algorithm, entirely using the search-and-prune technique. It can work only when the job number is small. The third one is similar to the first one, except that it uses Petrov’s approach (PT) to deal with job sequencing instead of searchand- prune. It can get a polynomial time complexity, thus being more suitable for real applications than the other two. Experiments are also made to compare the three proposed algorithms. A trade-off can thus be achieved between accuracy and time complexity.

Copyright

© 2007 Tzung-Pei Hong, Pei-Ying Huang, Gwoboa Horng and Chan-Lon Wang. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.