Simultaneous batching and scheduling for chemical processing with earliness and tardiness penalties

We consider the problem of determining the allocation of demand from differ ent customer orders to production batches and the schedule of resulting bat ches to minimize the total weighted earliness and tardiness penalties in co ntext of batch chemical processing. The problem is formulated as a mixed-in teger nonlinear programming model. An iterative heuristic procedure that ma kes use of the network nature of the problem formulation is presented to ap proximate an optimal solution. An algorithm polynomial in the number of bat ches to produce is also presented that optimally solves the problem under s pecial cost structures.