Slot-based vs. global event-based vs. unit-specific event-based models in scheduling of batch plants

During the last two decades, the problem of short-term scheduling of multiporuct and multipurpose batch plants has gianed increasing attention in the academic, research and manufacturing communities, predominantly because of the challenges and the high economic incentives involved. In the last ten years, numerous formulations have been proposed in the literature based on continuous representations of time. These continuous-time formulations have proliferated due to their established advantages over discrete-time representations and are often compared with one another in terms of computational complexity. the various continuous-time models can be broadly classified into three distinct categories: slot based, global-event based, and unit-specific-event based formulations. In this paper, we compare and evaluate the performance of these models, based on our implementations, using a benchmark example problem from the literature. Two different objective functions: maximization of profit and minimization of makespan are considered.