C Rajendran

The problem of scheduling in a static flowshop with sequence-dependent setup times of jobs (FSDS) is considered in this paper. A new heuristic to minimize the sum of weighted flowtime of jobs in a FSDS is proposed. An improvement scheme is supplemented to enhance the quality of the heuristic solution. An extensive computational performance analysis has shown that the proposed heuristic is computationally faster and more effective in yielding solutions of better quality than the existing heuristic. An interesting observation is that even though the proposed heuristic aims to minimize the sum of weighted flowtime of jobs (just like the existing heuristic), it fares much better than the existing heuristic in minimizing the maximum weighted flowtime of a job too. © 1997 Elsevier Science Ltd.

This study has been carried out in a sugar industry located in Tamil Nadu, India. During the production period, the plant is shut down for a couple of shifts for periodic overhauling, corrective and minor preventive maintenance activities, and inspections. This periodic shutdown is necessary because in the event of breakdown of machines, the plant is forced to crush the same amount of cane (that would have been crushed during the breakdown period) towards the end of the season when the recovery factor is low. The problem is to determine the frequency of this periodic shutdown maintenance in order to minimize the downtime losses that are time-dependent. A simulation model is developed towards this endeavor. © 1993.

We consider in this article the development of new and efficient dispatching rules with respect to the objectives of minimizing mean flowtime, maximum flowtime, variance of flowtime, proportion of tardy jobs, mean tardiness, maximum tardiness and variance of tardiness. We present five new dispatching rules for scheduling in a job shop. Some of these rules make use of the process time and work-content in the queue of the next operation on a job, by following a simple additive approach, in addition to the arrival time and dynamic slack of a job. An extensive and rigorous simulation study has been carried out to evaluate the performance of the proposed dispatching rules against those rules such as the SPT, WINQ, FIFO and COVERT, and the best existing rule. It has been observed that the proposed rules are not only simple in structure, but also quite efficient in minimizing several measures of performance. The important aspects of the results of experimental investigation are also discussed in detail.

We present two new dispatching rules for scheduling in a job shop. These rules combine the process-time and work-content in the queue for the next operation on a job, by making use of additive and alternative approaches. An extensive and rigorous simulation study has been carried out to evaluate the performance of the proposed dispatching rules compared with those by the SPT rule, the WINQ rule, a random rule based on the SPT and WINQ rules, and the best existing rule. The important aspects of the results of the experimental investigation are also discussed in detail.

The problem of scheduling in flowshop and flowline-based cellular manufacturing systems (CMS) is considered with the objectives of minimizing makespan, total flowtime and machine idletime. We first discuss the formulation of time-tabling in a flowline-based CMS. A genetic algorithm is then presented for scheduling in a flowshop. The proposed genetic algorithm is compared with the existing multi-criterion heuristic, and results of the computational evaluation are presented. We introduce some modifications in the heuristic seed sequences, while using them to ¡nitialÍ7.e subpopulations in the algorithm for scheduling in a flowline-based CMS. The proposed algorithm is also found to perform well for scheduling in a flowline-based CMS. © 1996 Taylor & Francis Ltd.