A computational evaluation of constructive heuristics for the parallel blocking flow shop problem with sequence-dependent setup times

Imma Ribas,Ramon Companys

doi:10.5267/j.ijiec.2021.1.004

Abstract

This paper deals with the problem of scheduling jobs in a parallel flow shop environment without buffers between machines and with sequence-dependent setup times in order to minimize the maximum completion time of jobs. The blocking constraint normally leads to an increase in the maximum completion time of jobs due to the blockage of machines, which can increase even more so when setup times are considerable. Hence, the heuristic to solve this problem must take into account these specificities in order to minimize the timeout of machines. Because the procedures designed to solve the parallel flow shop scheduling problem must deal not only with the sequencing of jobs but also with their allocation to the flow shops, 36 heuristics have been tested in this paper, of which 35 combine sequencing rules with allocation methods while the last one takes a different approach that is more related to the nature of this problem. The computational evaluation of the implemented heuristics showed good performance of the heuristic designed especially for the problem (RCP0) when the setup times are considerable. Furthermore, the evaluation has also allowed us to propose a combined heuristic that leads to good solutions in a short CPU time.

Highlights

This paper addresses the problem of scheduling n jobs in F identical parallel flow shops without buffers and with sequencedependent setup times to minimize the maximum completion time of jobs
The way in which these two related decisions are taken can affect the performance of heuristics, since the timeout of machines can be affected by both blocking and setup times
The heuristics with allocation methods 1, 2, 4, and 5 first order the jobs according to a sequencing rule, the jobs are assigned to the lines according to a given criterion

Summary

Introduction

This paper addresses the problem of scheduling n jobs in F identical parallel flow shops without buffers and with sequencedependent setup times to minimize the maximum completion time of jobs (makespan). The Parallel Permutation Flow Shop scheduling problem is similar to the Distributed Permutation Flow Shop scheduling problem (DPFSP), which deals with scheduling jobs in several identical factories in which each has one flow shop (line) in the production system Both problems are conceptually different, the solution methods proposed for one can be used to solve the other. To the best of our knowledge, the PBFSP with sequence-dependent setup times, has not been studied before, for which we have designed different constructive heuristics that combine several sequencing rules and allocation strategies in order to provide simple methods for solving the problem.

Problem definition

Constructive heuristics

Computational evaluation

Findings

Conclusions