GA-based resource-constrained flow-shop scheduling model for mixed precast production

Precast production tasks mainly consist of reinforcement cage prefabrication, form fabrication, installment of reinforcement cages, mosaic or tiling fitting, placing concrete, steam curing, cleaning and finishing operations. These tasks are generally arranged as a flow shop process, in which all the precast elements are processed in the same processing order through all the tasks. The precast production needs to take into account the impact of limited resources, including equipment and skilled labor, on production makespan. Moreover, to economically and effectively utilize these valuable resources, mixed production gains a potential advantage over the conventional separate production under resource constraints. A resource-constrained mixed-production flow-shop scheduling system is proposed in this paper. A genetic algorithm-based searching technique is adopted in the system to provide the optimal or near-optimal combination of production sequences, resource utilization, and minimum makespan in consideration of resource constraints and mixed production. Sensitivity analysis is further conducted to identify the impact of mixed production strategies on the overall precast production makespan. (C) 2002 Elsevier Science B.V. All rights reserved.