| This research addresses the Hot Strip Mill Production Scheduling Problem, a hard problem that arises in the steel industry when scheduling steel coil production. It can be modeled as a generalization of the Prize Collecting Traveling Salesman Problem, which is a generalization of the well-known Traveling Salesman Problem, with multiple and conflicting objectives and constraints.; The annual capacity of integrated steel plants is close to three million tons of coiled product, which means that the annual sales should amount to several million dollars. Fixed costs and initial investments at each of the facilities in the production chain are high. This requires that the company have a balance between capacities and demands at each production process. Although the hot strip mill operation is small relative to the magnitude of the total steel manufacturing process, its smooth and efficient operation is an important factor in overall plant profitability.; In this thesis we formulate this problem as a mathematical program and propose a heuristic method to determine good approximate solutions. The heuristic is based on Tabu Search and a new idea called "Cannibalization". This heuristic was applied to production data from Dofasco Inc., at Hamilton, Ontario, Canada. Comparison with actual production schedules indicates that the proposed method can produce significantly better schedules than the ones obtained with the current scheduling method. |
