SHORT-TERM SCHEDULING OF MULTIPRODUCT SINGLESTAGE BATCH PLANTS WITH PARALLEL LINES. Part one: BASIC MATHEMATIC FORMULATION

The short term scheduling of multiproduct singlestage batch plants with parallel lines involves the constraints of the release times and due dates of orders, as well as the sequence-dependent setup times and forbidden sub-sequences of orders production and the ready times of units. Taking the above constraints into consideration, this paper develops a short-term scheduling model for multiproduct singlestage batch plants with parallel lines using the notation of time slot and the continuous time domain representation. When the model is addressed, the allocation of orders and units to time slots is formulated as two sets of binary variables respectively. The model is formulated as a mixed integer linear programming (MILP) problem. It not only involves less binary variables than any other model based on the notation of time slot¹, but also can be used to optimize several types of objective functions. The second part of this paper introduces some heuristic rules, based on which the model is reformulated. A large number of examples are studied in the second part to demonstrate the effectiveness and applicability of the model.