Abstract
A scheduling method has been developed for steelmaking process, in which the problem is formulated in the minimum cost flow problem and the solution is decided using the sequential search approach. Sequential search algorithm is one of the well-known optimization method, but it often results in local optimization. Above all, for an integer problem as scheduling, which has a complex discrete structure, a sequential search approach is not available in many cases. To cope with this difficulty such methods as simulated-annealing and genetic algorithm are recently attempted, but the processing time should be much shorter for some actual application.
On the other hand, in the development of the actual application systems, it is often effective to utilize heuristics and to find a feasible semi-optimal solution. In this paper, a new method is proposed which contains heuristic rules in the process of sequential search. Many heuristic neighborhoods are defined in the form of flow modification patterns, and are selected to modify the network flow using heuristics of finding a good solution in the proper scheduling problem. The developed method was applied to the scheduling system in a steel plant, and the effectiveness of this approach was revealed in the actual application.
