A HYBRID HARMONY SEARCH ALGORITHM FOR THE NO-WAIT FLOW-SHOP SCHEDULING PROBLEMS

This paper presents a hybrid harmony search (HHS) algorithm for solving no-wait flow shop scheduling problems with total flowtime criterion. First, an initial harmony memory (HM) is formed by taking advantage of the NEH heuristic. Second, the harmony memory is divided into several small groups and each group executes its evolution process independently. At the same time, groups share information reciprocally by dynamic re-grouping mechanism. Third, to stress the balance between the global exploration and local exploration, a variable neighborhood search algorithm is developed and embedded in the HHS algorithm. In addition, a speed-up method is applied to reduce the running time requirement. Computational simulation results based on the well-known benchmarks and statistical performance comparisons are provided. It is shown that the proposed HHS algorithm is superior to the recently published hybrid DE-based (HDE) algorithm and hybrid particle swarm optimization (HPSO) algorithm in terms of effectiveness and efficiency.