CYCLE is an interface designed to use a program that applies the optimization algorithm developed by D. Birewar & I.E. Grossmann (1989) for zerowait scheduling of multiproduct batch plants. Given a multiproduct batch processing plant with M stages, Np different products, a total of N batches belonging to the Np products, and fixed processing and cleanup times, the algorithm finds an optimal schedule with the minimum cycle time or minimum makespan.
The following assumptions are considered:
The problem is modeled as an LP or MILP aggregated in the space of products, and the solution generated contains a group of schedules that can be easily derived with the algorithm implemented in CYCLE. Four cases are considered:

Min of cycle time considering single product campaigns

Min of cycle time considering mixed product campaigns

Min of makespan considering single product campaigns

Min of makespan considering mixed product campaigns
It is possible that the solution obtained includes subcycles or subtours. In this case, CYCLE eliminates them by applying a MILP formulation according toBirewar & Grossmann (1989).
This interface is written in language C and it is implemented on Windows NT, IBM RS6000, HP and SUN (SunOS and Solaris) workstations. The way this interface works is through the use of different menus; it is flexible and easy to use. Given the data of the problem, CYCLE creates a new GAMS file containing the model equations and optimizes the problem using the solvers
OSL, CPLEX or or SCICONIC for solving the LP and MILP.
CYCLE has been developed by Beatriz Bolio under the supervision of Ignacio E. Grossmann .
References for CYCLE:
Birewar, D. B. and I. E. Grossmann, Zerowait Scheduling for Multiproduct Batch Plants , I&EC RESEARCH, 1989, Vol. 28, No.9, pp. 13341345.
Bolio, Beatriz, Guidelines for CYCLE Interface, Carnegie Mellon University, Engineering Design Research Center, Pittsburgh, PA. 