Modeling And Solution Of Supply Chain Coordination Scheduling Problem In Cold Rolling

Steel-plant-wide supply chain management is to integrate the multiple production stages in the enterprise together, and supply chain scheduling involves the scheduling problem in the supply chain environment. Until now, the results of supply chain scheduling are comparatively less than supply chain planning. From the practical aspect, cold rolling plant includes multiple production lines, the materials of some production lines are supplied by other production line, and each production line has distinguished evaluation standard, therefore the production lines in cold rolling plant compose the supply chain in cold rolling. With this background, this dissertation proposes supply chain coordination scheduling problem in cold rolling so as to reduce the total production costs. The main works in this dissertation include:(1) The supply chain coordination scheduling problem in cold rolling is to make the schedules of the coils in cold rolling, continuous annealing, hot galvanizing and hot dipped zinc aluminum production lines, with consideration of the technical restrictions and the evaluation standard of each production line and time cohesion among the schedules for the involved production lines, in order to reduce the total changeover costs.(2) For supply chain coordination scheduling problem in cold rolling, a mixed integer nonlinear programming (MINLP) model is established. Due to the difficulties to solve the MINLP model, it is equivalently transformed to a linear model. Finally, the model is solved by CPLEX.(3) A differential evolution algorithm (DE) is designed and developed to solve the supply chain coordination scheduling problem in cold rolling. In the algorithm, the improvement strategies include encoding and decoding method based on discrete sequence for tackling the difficulties of solving discrete optimization problem by classical DE, the redefinition of addition and multiplication operations in mutation, the crossover operator dependent of the iteration and the chromosomes selection operation based on greedy strategy. The effectiveness of differential evolution algorithm can be verified by comparing the results of the proposed differential evolution algorithm with CPLEX and the heuristic algorithm based on experience.(4) According to the practical production requirements in the surveyed steel company, the supply chain coordination scheduling module is developed, and the proposed differential evolution algorithm is embedded in the module. With a developed human-computer interactive interface, the module can make decision of the schedules of the coils in acid rolling, continuous annealing, hot galvanizing and hot dipped zinc aluminum production lines. Meanwhile, two parameter configuration modules for steel-making planning are developed.