Abstract

COMPANYS, Ramón  and  D' ARMAS, Mayra. Operation scheduling with setup times by local optimization algorithms. uct [online]. 2005, vol.9, n.35, pp.155-162. ISSN 1316-4821.

The objective of this work is to evaluate, by means of computer tests, the behavior of the direct heuristics algorithms and local optimization to solve the operation scheduling problem. This article refers to the operation sequence problem on a machine with families of products, where setup times are separated from the processing times, and are dependent on the sequence, with the objective of minimizing the sum of delays. The algorithms were codified in Visual Basic and 1000 samples were tested with a number of families between 4-6 and with a total number of pieces between 15-25. Computer results showed that: (a) Critical Index heuristic is the one that provides better initial solutions; (b) although with Earliest Due Date heuristic a greater number of worse initial solutions was obtained, with the application of the improvement heuristic, good results are achieved; (c) the use of a better initial solution does not guarantee a better result after the phase of local improvement (d) the capacity of improvement of the heuristic algorithms of local optimization is dependent on the initial heuristic used.

Keywords : Direct Heuristics Algorithms; Operation Algorithms; Operation Scheduling; Sequence-Dependent Setup Times.