Minimizing makespan in a blocking flowshop using genetic algorithms

Article Abstract:

We consider the problem of minimizing the makespan of n jobs in an m-machine flowshop operating without buffers. Since there is no intermediate storage, a job here cannot leave a machine until the machine downstream is free. When that is the case, the job is said to be blocked. This "blocking flowshop" problem is known to be strongly NP-hard for the shop having more than two machines. In this paper, we develop a genetic algorithmic approach to solve large size restricted slowdown flowshop problems of which blocking flowshop problems are a special case. Abadi (Flowshop scheduling problems with no-wait and blocking environments: A mathematical programming approach. Ph.D Thesis, Department of Industrial Engineering, University of Toronto, Canada, 1995) has established a connection between the blocking flowshop problem and a no-wait flowshop in which jobs do not wait between operations. He uses the idea of deliberately slowing down the processing of certain operations. We utilize this concept to evaluate the makespan (fitness) of the solutions generated by genetic algorithms. Computational results indicate that a genetic algorithm with optimized parameters for controlling the evolution of solutions consistently performs significantly better than the heuristic for blocking flowshops developed in a recent Ph.D. thesis by Abadi. The comparison is made for the problems with sizes up to 20 machines and 250 jobs. [C] 2001 Published by Elsevier Science B.V. All rights reserved. Keywords: Manufacturing; Blocking flowshop; Slowing down; Genetic algorithm

United States, Research, Production (Economics)

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Developing material delivery processes in cooperation: an application example of the construction industry

Article Abstract:

A study developed a new method for the cooperative development of material delivery processes between construction firms and materials suppliers in the construction and building trades in Finland. The approach was tested on the Turku, Finland TULO project involving logistics development that was carried out between May 1994 and Feb 1995. Results derived from this case project and experiences on cooperative development that were gleaned from 14 construction firms and 11 material suppliers attest to the efficacy of the cooperative development approach.

Materials & Handling Management, Special Trade Contractors, Construction Trades, Methods, Management, Construction industry, Building tradespeople, Materials handling, Industrial suppliers, Delivery of goods, Deliveries (Transportation), Materials management, Material requirements planning

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