Scheduling of steel-making and continuous casting system using the surrogate subgradient algorithm for lagrangian relaxation

How to make a good schedule in a computationally efficient manner and be able to assess the quality of schedule to improve the steel production and effectively assist the reschedule during the process of steel-making and continuous casting are the key factors for iron and steel production manufacturing productivity. The surrogate subgradient algorithm for lagrangian relaxation is introduced to solve the problem. The surrogate subgradient method can get a proper direction without solving all the separated charge´s schedule to optimize dual functions for separable steel-making and continuous casting schedule problems which are relaxed by lagrangian relaxation method. The results shows that this method can obtain better directions with less efforts and less times to get better schedule results.