An Improved Local Search Method for Solving Job Shop Scheduling Problems

A Combined Algorithm for Solving Job Shop Scheduling Problems

“…The definition of a neighborhood is always important for improving the accuracy of solutions. A definition of neighborhood was proposed in the paper (Nakano et al, 2001) and an optimal size K of neighborhood was estimated by a large number of computational experiments. Figure 1 shows the definition of neighborhood.…”

“…A large number of computational experiments were carried out by using ILS and changing the parameter κ(= NH K ) (Nakano et al, 2001). The optimal size of neighborhood was obtained as κ = 0.54.…”

“…In the paper (Tian et al, 2000), a tabu search with a new neighborhood was proposed for reducing the term of memory and computational time. In another paper (Nakano et al, 2001), an improved local search method (ILS) with two search stages was proposed for solving JSSP. An optimal size of neighborhood was obtained from a large number of statistic experiments.…”

“…In this paper, a combined algorithm consisting of two stages of approaches is proposed for solving JSSPs. The first stage of approach called semi-active scheduling approach (SSA) is proposed for obtaining a local optimal solution in a short time by using ILS and the neighborhood search technique proposed in the paper (Nakano et al, 2001). The second stage of approach called active scheduling approach (ASA) is proposed for improving the solution obtained from SSA and for preventing the solution from trapping in the local minimum by making good use of the resources with reducing the idle time in the processes.…”

“…In addition, we assume that the total number of search points is limited in this paper. Therefore, the assignment of the local search effort and the global search effort, and the optimal size of the neighborhood are adopted according to the results obtained from the paper (Nakano et al, 2001). The proposed algorithm is applied to solving classical JSSPs, and the effectiveness is examined by comparing it with GA.…”