Strengthening the continuous time formulation of a mixed plant cyclic scheduling problem

The problem addressed is the optimization of the cyclic schedule of a mixed plant in order to maximize its productivity. A mixed plant is composed of batch and continuous tasks. A batch task has a fixed processing time and outputs at the end a fixed amount of product. A continuous task is processed continuously and its decision variable is the processing rate at which this continuous task is performed. Both tasks consume resources whose capacity or availability is limited.