Flow-shop sequencing using hybrid simulated annealing

Simulated annealing (SA) heuristics have been successfully applied on a variety of complex optimization problems. This paper presents a new hybrid SA approach for the permutation ¯ow-shop scheduling (FSS) problem. FSS is known to be NP-hard, and thus the right way to proceed is through the use of heuristics techniques. The proposed approach combines the characteristics of a canonical SA procedure together with features borrowed from the ®eld of genetic algorithms (GAs), such as the use of a population of individuals and the use of a novel, non-standard recombination operator for generating solutions. The approach is easily implemented and performs near-optimal schedules in a rather short computation time. Experiments over multiple benchmarks test problems show that the developed approach has higher performance than that of other FSS meta-heuristic approaches, generating schedules of shorter makespans faster. The experiments include comparisons between the proposed hybrid model, a genetic algorithm, and two other standard simulated annealing approaches. The ®nal solutions obtained by the method are within less than 1% in average from the optimal solutions obtained so far.