Integrated operations scheduling with delivery deadlines

An integrated scheduling problem of supply and distribution operations in a make-to-order supply chain is considered. The supply chain consists of contracted suppliers, capacitated processing centers, and many demand points. Processing centers customize and/or configure semi-finished products supplied by suppliers to finished products in terms of the requirements of demand points: order quantity and delivery deadline. The problem is to find the assignment of both suppliers and demand points to processing centers and the schedules for supply and distribution operations such that the total costs of shipping and penalty that unfulfilled customer orders incur are minimized, subject to network capacity and deadline constraints. In this paper, a heuristic algorithm is developed, based on partial relaxation and median threshold, which makes it possible to avoid dealing with the generalized assignment problem, a strongly NP-hard problem, in the solution process. Computational tests are performed over test cases randomly generated to assess the performance of the proposed algorithm. As compared to the use of commercial optimization package, CPLEX, computational results show that the proposed algorithm is able to find a good near-optimal solution to this problem with remarkably less computational time.