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...

Solving efficiently complex problems using metaheuristics, and in particular local search algorithms, requires incorporating knowledge about the problem to solve. In this paper, the permutation flowshop problem is studied. It is well known that in such problems, several solutions may have the same fitness value. As this neutrality property is an important issue, it should be taken into account ...

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 deals with a flowshop scheduling problem with a special blocking RCb (Release when Completing Blocking). In some industrial environments, such flexible production systems can be encountered. Genetic algorithms are good methods to solve these problems. A method is proposed to further improve solutions already found by genetic algorithms. It consists in marking out recurrent genes asso...

In this article, we consider the minimization of the total tardiness in a flexible job-shop. In our knowledge, this criterion is not previously studied for this type of shop configuration. The total tardiness criterion was mainly considered in the single machine problem (Chu [Chu92] and Souissi et al. [SKC04]). Few references studied this criterion in a job-shop configuration. The priority rule...

Scheduling problems involving both earliness and tardiness costs became more important in recent years. This kind of problems include both earliness and tardiness penalties and tries to reduce them. In this study a case study from real world is investigated. Since the machine is bottle neck in the production line and all jobs have a common restrictive due date and different earliness and tardin...

The objective of this paper is to propose a scheduling problem for multiple automated guided vehicles (AGVs) in a manufacturing system. Considering the due date of AGVs requiring for material handling among shops in a job shop layout, their earliness and tardiness are significant in satisfying the expected cycle time and from an economic view point. Earliness results in AGVs waiting and tardine...

Two optimal algorithms, MTA* and MT-RBA*, are presented to find the optimal yard crane (YC) job sequence for serving a fleet of vehicles for delivery and pickup jobs with scheduled deadlines and predicted vehicle arrival times. The objective is to minimize the total tardiness of incoming vehicle jobs. This is important for minimizing vessel turnaround time. In the search for an optimal job sequ...

Quality control lead times are one of most significant causes of loss of time in the pharmaceutical and cosmetics industries. This is partly due to the organization of laboratories that feature parallel multipurpose machines for chromatographic analyses. The testing process requires long setup times and operators are needed to launch the process. The various controls are non-preemptive and are ...