Assignment and sequencing models for the scheduling of process systems

This paper presents an overview of assignment and sequencing models that are used in the scheduling of process operations with mathematical programming techniques. Although scheduling models are problem specific, there are common features which translate into similar types of constraints. Two major categories of scheduling models are identified: single-unit assignment models in which the assignment of tasks to units is known a priori, and multiple-unit assignment models in which several machines compete for the processing of products. The most critical modeling issues are the time domain representation and network structure of the processing plant. Furthermore, a summary of the major features of the scheduling model is presented along with computational experience, as well as a discussion on their strengths and limitations.