INTEGRATED PRODUCTION AND DISTRIBUTION SCHEDULING ON A EUROPE-WIDE BASIS

We consider a large-scale scheduling problem in which three multipurpo se production facilities in different countries supply a large portfol io of fast moving consumer products to the European market. The operat ion of each multipurpose plant is characterised by complex internal de cisions concerning the allocation of production resources over the wee k-long planning horizon considered. In addition, there is a large degr ee of inherent flexibility in the overall system, particularly regardi ng which warehouses are served by which plant. As a consequence, in or der for the most efficient schedule to be found, all three plants must be considered in detail and simultaneously as one large production sy stem. We achieve this by using a very general scheduling representatio n allowing important features such as equipment change-overs and limit ed intermediate storage to be modelled. As the size of this fully deta iled formulation is beyond the scope of current computing resources, w e generate an approximate formulation from it in a formal way by aggre gating constraints. Its solution gives a tight upper bound on the prod uction capacity of the system and allows the problem to be decomposed into smaller sub-problems, each involving a single plant. Solving thes e sub-problems involves finding a detailed schedule separately for eac h plant using production targets set by the aggregate solution.