Scheduling of steelmaking-continuous casting process using deflected surrogate Lagrangian relaxation approach and DC algorithm

This paper investigates a hybrid flowshop scheduling (HFS) problem in the steelmaking continuous casting (SCC) process. Firstly, a mathematical model is built for the SCC scheduling problem. By relaxing the machine capacity constraint, the SCC scheduling problem can be transformed into a DC (difference of convex functions) programming problem, which can solved by using DC algorithm. Under some reasonable assumptions, the convergence of the DC algorithm is analyzed. Secondly, we propose an effective and efficient deflected surrogate subgradient method with global convergence to solve the Lagrangian dual (LD) problem. Thirdly, a simple heuristic method is designed to obtain a feasible scheduling. Lastly, we report some computational experiments to demonstrate the effectiveness of the proposed surrogate subgradient method by comparing with other similar surrogate subgradient methods.