New scheduling problems with perishable raw materials constraints

In production manufacturing systems, raw materials that are required for the production process are supposed to be present in sufficient quantities. The ordering of these products is given by an inventory management policy. We consider in this paper raw materials, that are present in sufficient quantities and that can be stored for a long time in containers under specific conditions (temperature, pressure, ...). The peculiarity is that the quality of these raw materials decreases as soon as they are open for being used. At this moment, the product has to be used before a given deadline, or it is lost. Two types of objective functions are associated to the use of such raw materials: the total cost of lost products (economic objective) and the total quantity of lost products (environmental objective). We present in this paper this new scheduling framework, which brings new constraints and new objective functions. We show that the single machine problem with equal-length jobs and only one product is already NP-hard and we propose mathematical formulations for two single-machine problems and an MIP model, which is briefly evaluated.