No-wait flow shop problem with two mixed batching machines
Résumé
We study a problem of scheduling $n$ tasks in a no-wait flowshop consisting of two batching machines. Each task has to be processed by both machines. All tasks visit the machines in the same order. Batching machines can process several tasks in batch so that all tasks of the same batch start and complete together. The processing time of a batch on the first batching machine is equal to the maximal processing time of the tasks in this batch, and on the second batching machine is equal to the sum of the processing time of tasks in this batch. We assume that the capacity of any batch on the fist machine is bounded, and when a batch is completed on an upstream machine should immediately transferred to the dowstream machine. The aim is to make batching and sequencing decisions so that the makespan is minimized. We prove that the makespan minimization is NP-Hard in strong sense, and we give some well solvable cases.