João Vitor Moccellin

A high quality solution constructive heuristic for flow shop sequencing

This paper addresses the flow shop sequencing problem. Following an investigation of the problem characteristics, a property of this scheduling problem is presented, and is used for the development of a new constructive heuristic with the objective of minimizing the total time to complete the schedule (makespan). The new method, denoted by N&M, is compared with the best constructive heuristic reported in the literature, named NEH. Results from computational experience have shown that for problems having up to 10 machines and 100 jobs, the new heuristic outperforms, on average, the NEH heuristic. There is no significant difference regarding computation effort for both NEH and N&M heuristics.

Reducing mean flow time in permutation flow shop

This paper deals with the traditional permutation flow shop scheduling problem with the objective of minimizing mean flowtime, therefore reducing in-process inventory. A new heuristic method is proposed for the scheduling problem solution. The proposed heuristic is compared with the best one considered in the literature. Experimental results show that the new heuristic provides better solutions regarding both the solution quality and computational effort.

Heuristic for flow shop sequencing with separated and sequence independent setup times

This paper deals with the permutation flow shop scheduling problem with separated and sequence-independent machine setup times. A heuristic method with the objective of minimizing the total time to complete the schedule is introduced. The proposed heuristic is based on a structural property of this scheduling problem, which provides an upper bound on the idle time of the machines between the completion of the setup task and the beginning of job processing. Experimental results show that the new heuristic outperforms two existing ones.

Métodos heurísticos construtivos para redução do estoque em processo em ambientes de produção flow shop híbridos com tempos de setup dependentes da sequência

This paper presents an investigation about the hybrid flow shop problem with asymmetric sequence dependent setup times and proposes constructive heuristic methods to minimize the mean flow time aiming at fast demand response and work in process reduction. The proposed heuristic methods were compared among themselves since no constructive heuristic method was found in the literature on the scheduling problem considered in this work. A study on the influence of the relation between the orders of magnitude of processing and setup time for each method was carried out. The influence of the scheduling procedure adopted was investigated to assess the performance of the methods use

Uma propriedade estrutural do problema de programação da produção flow shop permutacional com tempos de setup

This paper deals with the permutation flow shop scheduling problem with separated machine setup times. As a result of an investigation on the problem characteristics a structural property is introduced. Such a property provides an upper bound on the idle time of the machines between the setup task and the job processing. As an application of this property, the original scheduling problem with the makespan criterion can be heuristically solved by an analogy with the asymmetric traveling salesman problem.

Novas regras de prioridade para programação em flexible flow line com tempos de setup explícitos

This paper presents twelve methods for makespan minimization for flexible flow line scheduling problems. This environment is characterized by the ability of jobs to skip stages. Sequence-independent setup times, which can be either anticipatory or non-anticipatory, are also considered. The statistics used to evaluate the heuristic performances were the rate of success (in finding the best solution), the relative deviation, the standard deviation of the relative deviation and the average computation time. A lower bound for makespan was developed to evaluate the solution quality of the proposed methods. The computational tests proved the effectiveness of the heuristic based on the initial sequence using the descending order of the sum of the processing and setup times of all stages and the sequencing of subsequent stages by the order of the job release times.

ANÁLISE MULTI-CRITÉRIO NA PROGRAMAÇÃO DA PRODUÇÃO EM SISTEMAS NO-WAIT FLOW SHOP

Este artigo trata do problema de programacao de operacoes em um ambiente de producao no-wait flow shop, tendo como objetivo a minimizacao da soma ponderada entre a duracao total da programacao das tarefas e a soma dos tempos de fluxo das tarefas. A partir da analise das caracteristicas do problema, um novo metodo heuristico e apresentado e comparado com o melhor metodo da literatura. Os resultados experimentais mostraram a superioridade do novo metodo para o conjunto de problemas tratados em relacao a qualidade das solucoes obtidas.