Resource-task network

A simpler and general discrete time scheduling formulation can also be derived by means of the Resource Task Network concept proposed by Pantelides [10], The major advantage of the RTN formulation over the STN counterpart arises in some problems involving many identical pieces of equipment. In these cases, the RTN formulation introduces a single binary variable instead of the multiple variables used by the STN model. The RTN-based model also covers all the features at the column on discrete time in Table 8.1. In order to deal with different types of resources in a uniform way, this approach requires only three different classes of constraints in terms ofthree types of variables defining the task allocation, the batch size, and the resource availability. Briefly, this model reduces the batch scheduling problem to a simple resource balance problem carried out in each predefined time period. 

This paper has addressed the optimal periodic scheduling of an industrial batch plant from a new perspective. The aim has been to select a convenient number of equipment units so as to rninirnize the total equipment allocation cost and hence achieve a trade-off between a low makespan and high free capacity. A decomposition method based on a Resource-Task Network discrete-time formulation has been proposed that, when compared to the solution of the full problem, was able to reduce the total computational effort by one order of magnitude without severely compromising optimality. 

Pinto etal. (2005) Resource Task Network unified MILP Maximization of annualized B... 

For the Resource-Task Network, RTN and considering directly the definitions established by Pantelides (1994) for Tasks and Resources the resulting RTN leads to 24 nodes (Figure 3). 

Barbosa-Pdvoa, A.P., Pantelides, C.C., 1997, Scheduling and design of multipurpose plants using the resource-task network unified framework. Computer Chem. Engng, 21b, S703-S708. 

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