The Unit-Operation-Stock Superstructure (UOSS) and the Quantity-Logic- Quality Paradigm (QLQP) for Production Scheduling in the Process Industries

It is well-known that production scheduling can be largely categorized into open and closed-shops (Graves (1981)). Open-shops are job-shops, flow-shops, machine-shops and project-shops and deal exclusively with the assignment, sequencing and timing decisions (Pinedo (1995)). Closed-shops on the other hand also deal with the same three decision-groups as open-shops but they also must decide on the sizing of lots, charges, batches and movements in order to properly program production especially with finite inventory capacity. Arguably open-shops are a subset of closed-shops. The purpose of this article is to overview a production model and its data which is comprehensive enough to schedule the breadth and depth of all plants found in the process industries. We achieve this by extending the state and resource-task networks (STN and RTN; Kondili et. al. (1993) and Pantelides (1994)) to explicitly include the aspects of limited routings between unit-operations and other unit-operations up and downstream in the material flow path as well as dealing directly with the complexity of charge/batch-splitting into movements. We call this novel production modeling approach the unit-operation-stock superstructure (UOSS) which is the cross-product of the physical (units) and the procedural (operations) models or substructures.