This paper deals with a realistic variant of flowshop scheduling, namely the hybrid flexible flowshop. A hybrid flowshop mixes the characteristics of regular flowshops and parallel machine problems by considering stages with parallel machines instead of having one single machine per stage. We also investigate the flexible version where stage skipping might occur, i.e., not all stages must be vi...

We consider flowshop environments that consist of multiple stages and multiple machines in each stage. The flowshops are flexible in the sense that a task within a stage can be processed by any of the machines in the stage. We refer to this design as the hybrid flowshop. Our objective is to schedule a set of n jobs so as to minimize makespan. The problem is NP-complete even in the case of a sin...

The hybrid or flexible flowshop problem is a generalization of the flowshop in such a way that every job can be processed by one among several machines on each machine stage. In recent years a number of effective exact methods have been developed. A major reason for this progress is the development of new job and machine based lower bounds as well as the rapidly increasing importance of constra...

this paper considers the problem of scheduling hybrid flowshops with machine availability constraints (mac) to minimize makespan. the paper deals with a specific case of mac caused by preventive maintenance (pm) operations. contrary to previous papers considering fixed or/and conservative policies, we explore a case in which pm activities might be postponed or expedited while necessary. regardi...

Scheduling in chemical flowshops is one of a number of important industrial problems which are potentially amenable to solution using the genetic algorithm. However the problem is not trivial: flowshops run continuously, and for efficient operation those controlling them must be able to adjust the order in which products are made as new requests are received. In addition, there are in principle...

The paper describes an algorithm for solving the scheduling problem of a hybrid flowshop (flowshop with multiple processors, FSMP). The algorithm is a combination of genetic algorithm and tabu search, and the batch processes it is applied on are modeled by a model of time requirements. The paper describes the algorithm and compares its performance with other optimization techniques.

In this study, we consider a problem of estimating order flowtimes in two-stage hybrid flowshops, where orders arrive dynamically and various scheduling schemes can be used. To solve the problem, we devise several order flowtime estimation methods, and each method is specific to the scheduling scheme used in the shop. Whenever an order arrives, the flowtime of the order is estimated by using on...