A hybrid approach that combines dispatching rules and variable neighborhood search for flow shop problems

• Main Authors: Kai-ying Chen, 陳楷縈
• Other Authors: 盧銘勳
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/40662087252731449614

碩士 === 逢甲大學 === 工業工程與系統管理學研究所 === 100 === In a rapidly changing industrial environment, scheduling decisions are critical to resource allocations for industrial production. Manufacturers demand high utilization rates and effective allocations of resources. This research addresses flow shop scheduling problems; because these problems are NP-Hard, dispatching rules are combined with variable neighborhood search (VNS). Five different levels of buffer capacity are considered. Makespan and mean flow time are the relevant performance indicators. Analysis of schedules formed by exhaustive enumeration showed that for problems in simulation scene with few machines and few jobs, buffers were not required. Variable neighborhood search required less CPU time than exhaustive enumeration and also produced better solutions. Approximately optimal solution obtained by VNS were better than initial solution obtained by dispatching rules. The degree of improvement obtained by VNS was proportional to the variation in processing times. The results for problems with infinite buffers showed good makespan values, and the results for problems with no buffers showed good mean flow time values.