IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

The problem of family and job scheduling in a flowline-based manufacturing cell is considered with the criterion of minimizing makespan, followed by the criterion of minimizing total flowtime, and finally with the bi-criteria of minimizing makespan and total flowtime. We reckon the presence of missing operations in the manufacturing cell and present the correct problem formulation for time-tabling. We then propose the Genetic Algorithm (GA) for part-family scheduling and then for job scheduling within part-families. The proposed algorithm is compared with the existing algorithm and results are reported. © 1994.

Department of Management Studies

Computers and Industrial Engineering

A genetic algorithm for family and job scheduling in a flowline-based manufacturing cell

We consider the flowshop scheduling problem with the twin-objective of minimizing makespan and total flowtime. We apply the Simulated Annealing (SA) technique to develop the proposed heuristic. Two new heuristics are proposed to provide the seed sequences for the SA heuristic. When compared with the existing heuristics, the proposed SA heuristic is found to perform much better. © 1994.

A simulated annealing heuristic for scheduling in a flowshop with bicriteria

Spare parts constitute a significant portion of the inventory in any manufacturing organisation. Specifying optimal inventory control policies for spares requires the use of forecasting techniques, ABC analysis, FSN analysis, VED analysis, etc. While the ABC and FSN analyses are straightforward, evaluation of the criticality of spares by using quantitative measures is difficult and problematic while performing VED analysis. This paper describes the use of Saaty's analytic hierarchy process for evaluating the criticality of spares. A three-level hierarchy has been suggested. Criteria influencing the criticality of different spare parts have been identified and the alternative modes for each criterion have been specified. The model has been used to obtain absolute measurements of criticality which can be compared with prespecified numerical limits for classifying spare parts as Vital, Essential, or Desirable. The model's working has been demonstrated through an illustration involving a spare part in the inventory system of a large manufacturing organisation. © 1994.

International Journal of Production Economics

Criticality analysis of spare parts using the analytic hierarchy process

The problem of scheduling in a cellular manufacturing system is considered with the objective of minimizing the sum of completion times (or total flow time) of jobs. A correct formulation of recursive equation for the flowline-based cellular manufacturing system is first proposed. Subsequently a heuristic is developed to obtain a sequence that minimizes total flow time in a flowline cell. The proposed heuristic makes use of the simulated annealing technique and is developed in two stages. A good initial heuristic seed sequence obtained in the first stage is improved upon by a proposed new variant of the simulated annealing technique wherein three different perturbation schemes have been experimented with. One of the perturbation schemes is newly proposed in this paper and is called the Adjacent interchange scheme. The proposed simulated annealing algorithm has been compared with the existing heuristics for minimizing flow time and has shown consistently good and superior solutions. © 1993 Taylor & Francis Group, LLC.

International Journal of Production Research

Scheduling in a cellular manufacturing system: A simulated annealing approach

In this paper we present a new dispatching rule which is dynamic and global in its structure. The rule adapts itself to the variation in the shop floor utilization level and assigns appropriate weights to the process time and due date information accordingly. Another important feature of the proposed rule is that the weights to the two components, viz. the process time and the due date components, differ from machine to machine. The results of a simulation study are presented to demonstrate the effectiveness of the rule with respect to the rules most commonly used in industry and the proven rules reported in the literature. The proposed rule is found to perform quite well with respect to mean flow time, mean tardiness and variation in tardiness. © 1993.

An efficient dynamic dispatching rule for scheduling in a job shop

We present two simple heuristic algorithms for scheduling to minimize makespan in the constrained (or no-wait) flowshop. While developing the heuristics, we first present the methods to obtain the initial seed sequences, and subsequently obtain better solutions by an improvement technique. When evaluated over a large number of problems of various sizes, the solutions yielded by the proposed heuristic algorithms are found to be reasonably accurate, and superior to the ones given by the existing heuristics. © 1993.

Heuristic algorithms for scheduling in the no-wait flowshop

Level scheduling involves the production of products in many batches with reasonably small batch quantities during a scheduling period. The problem under study is quite complex since products have different demand rates and the product setup time is sequence-dependent. First an analysis has been carried out to identify those products for which level scheduling will be carried out. Next the sequence of manufacture of these products is determined by considering the sequence-dependent matrix and using a heuristic algorithm. A simple expression for obtaining the number of maximum possible runs (or batches) of such a sequence is presented. © 1993.

Computers in Industry

Level scheduling in an automobile electrical ancillary industry

The problem of finding the best permutation schedule for a flowshop has engaged the attention of researchers for almost four decades. In view of its NP-completeness, the problem is not amenable to the development of efficient optimizing algorithms. A number of heuristics have been proposed, most of which have been evaluated by using randomly generated problems for a single measure of performance. However, real-life problems often have more than one objective. This paper discusses a live flowshop problem that has the twin objectives of minimizing the production run-time as well as the total flowtime of jobs. Five heuristics are evaluated in this study and some interesting findings are reported. © 1993 Taylor & Francis Group, LLC.

GENERAL

Production Planning and Control

Evaluation of heuristics for scheduling in a flowshop: A case study

In this article, a heuristic algorithm is presented for scheduling in a flowshop to minimize the total flowtime of jobs. A heuristic preference relation is developed and used as the basis for job insertion to build up the complete schedule. When evaluated over a large number of problems of various sizes, the proposed heuristic is found to be very effective in yielding optimal or near-optimal solutions and emerges superior to the existing heuristics. © 1993.

Heuristic algorithm for scheduling in a flowshop to minimize total flowtime

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.

Scheduling of maintenance activities in a sugar industry using simulation

Most algorithms on flowshop scheduling assume that every stage has a single processor or machine only. With a view to achieve the practical objective of minimizing total flowtime, a branch-and-bound algorithm for obraining a permutation schedule for the multi-stage flowshop with parallel processorsis presented. Computational experience with the proposed algorithm and the existing single-processor algorithms revelas that most of the parallel-processor problems are solved faster and easier. The performance of the existing procedures is also evaluated in the parallel-processor environment. Since the flowshop scheduling problem is NP-complete, a heuristic algorithm for scheduling in a two-stage parallel-processor flowshop is proposed. The heuristic solutions, when compared with the optimal solutions given by the proposed branch-and-bound method, are found to be near-optimal. © 1992.

European Journal of Operational Research

A multi-stage parallel-processor flowshop problem with minimum flowtime

Three heuristic algorithms for flowshop scheduling with the objective of minimizing total flowtime are presented in this paper. Since the flowshop scheduling problem has been found to be an NP-complete problem, the development of heuristic algorithms that guarantee fairly accurate solutions becomes necessary. The proposed algorithms are found to give consistently near-optimal solutions and fare better than the existing methods. © 1992.

An efficient heuristic approach to the scheduling of jobs in a flowshop

The existing algorithms for optimizing the flowshop scheduling problem with the objective of minimizing makespan assume that every stage has a single processor. This paper relaxes this assumption and presents a branch-and-bound algorithms for scheduling in the flowshop with parallel processors. The computational experience on the working of the algorithm is also reported. © 1992.

Scheduling in n-job, m-stage flowshop with parallel processors to minimize makespan

In this article we present two heuristic algorithms for scheduling in the constrained or continuous flow shop to minimize total flow time of jobs. Two heuristic preference relations are used as the basis for job insertion to build up a schedule by the heuristics. When evaluated over a large number of problems of various sizes, the heuristics are found to be very effective in yielding near‐optimal solutions. Copyright © 1990 Wiley Periodicals, Inc., A Wiley Company