Estudo da influência da programação do primeiro estágio em flow shop híbridos com tempos de setup explícitos

Abstract

This study addresses the problem of hybrid flow shop scheduling with se-quence-independent setup times. Four constructive heuristic methods (called LPT, TOTAL, SCT and LPST) were proposed with the aim of assessing the impact of the schedule of the first stage of production in this environment. The minimization of the total time to complete the schedule (makespan) was used as a performance criterion. The LPT method is based on the well-known Longest Processing Time rule, which organize tasks in the ascending order of the sum of processing times of all the stages. The TOTAL method uses the idea of Vogel Approximation Method, considering the matrix composed by the sum of processing and setup times of all stages. The SCT method chooses the pair machine-job that leads the Shortest Completion Time. And the LPST method assigns to the lower load machine the job with the largest sum of processing and setup times of the first stage. The results of computing experiments showed that the SCT method was much higher, with 55.3% of success, while LPT obtained 26.9%, TOTAL reached 16.4% and lastly LPST presented 2.2% of success.