C Rajendran

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.

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.

This paper is the second of two papers that deal with the problem of scheduling in the permutation flowshop and flowline-based manufacturing cell with the consideration of different buffer-space requirements (or different in-process inventory levels) for jobs and the constraints on buffer-storage capacity between machines. We consider two sets of twin objectives of scheduling: one set consists of minimizing the idle-time of machines and waiting-time of jobs, and another set consists of minimizing idletime of machines and weighted waiting-time of jobs. We present a bicriterion heuristic, with a variant, to obtain a sequence that minimizes the twin objectives under consideration. The heuristic works in two phases. The first phase, i.e., ‘initial seed-sequence generation phase’, deals with the development of a good seed sequence with respect to twin objectives under consideration. The second phase is the ‘improvement phase’ in which the seed sequence, obtained from the first phase, is improved by using a new perturbation technique called ‘multiple random insertion technique’. An extensive computational experimentation has been carried out to compare the performance of the proposed heuristic and its variant with those of the existing heuristics for scheduling in the buffer-constrained and flowline-based manufacturing systems under study. The results of the experimentation reveal that the proposed heuristic and its variant emerge to be better than the existing heuristics. © 1997 Taylor and Francis Group, LLC.

In this article we present a real-life study of a job shop manufacturing ball screws. The aim of the study is to suggest an efficient scheduling and due-date setting policy for the shop. Three different methodologies for setting parameter coefficients for due-date setting in a job shop are proposed. These methodologies are based on a search algorithm, simulated annealing algorithm, and a combination of simulated annealing algorithm and regression analysis. It is found that the combination of a simulated annealing algorithm with regression analysis provides better due-date estimates in minimizing the root mean square of lateness. © 1995 Taylor & Francis Group, LLC.

This paper presents a comparative study on the performance of dispatching rules in the following sets of dynamic manufacturing systems: flowshops and jobshops, and flowshops with missing operations and jobshops. Three new dispatching rules are proposed. We consider a total of 13 dispatching rules for the analysis of the relative performance 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. First, we carry out the simulation study in flowshops with jobs undergoing processing on all machines sequentially and in jobshops with random routeing of jobs. The results of the study reveal some interesting observations on the relative on the performance of the dispatching rules in these two types of manufacturing systems. Next, we consider flowshops with missing operations on jobs and jobshops with random routeing of jobs. We observe some interesting results in the sense that the performance of dispatching rules is being influenced by the routeing of jobs and shopfloor configurations.

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.

We address the problem of scheduling in a Kanban-controlled flowshop with dual blocking mechanisms. The flowshop is also characterized by missing operations for part-types. We first present recursive equations for time-tabling of containers in a given sequence. We then present two heuristics for scheduling with the objectives of minimizing the sum of weighted waiting-time of containers and weighted flowtime of part-types. An extensive computational evaluation of the proposed heuristics is also presented. © 1997 Taylor & Francis Group, LLC.

The problem of scheduling in a flowshop, where setup, processing and removal times are separable, is considered with the objective of minimizing makespan. Heuristic algorithms are developed by the introduction of simplifying assumptions into the scheduling problem under study. An improvement method is incorporated in the heuristics to enhance the quality of their solutions. The proposed heuristics and an existing heuristic are evaluated by a large number of randomly generated problems. The results of an extensive computational investigation for various values of parameters are presented. © 1997 Taylor & Francis Ltd.

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.

The problem of scheduling in flowshop and flowline-based manufacturing cell (or simply, a cell) is considered with the objective of minimizing mean tardiness of jobs. A heuristic algorithm, based on the simulated annealing (SA) technique, is developed. We propose a method for obtaining a seed sequence. We then present two perturbation schemes, the Random Insertion Perturbation Scheme and the Curtailed Random Insertion Perturbation Scheme. The proposed SA algorithm with two schemes is evaluated against the existing heuristics that seek to minimize mean tardiness of jobs. The results of the computational evaluation reveal that the proposed SA algorithm with two schemes performs better than the existing heuristics. A similar performance is also observed in the cell scheduling problem. We have also evaluated the effectiveness of the SA algorithm in minimizing the weighted mean tardiness of jobs. © 1998 Elsevier Science Ltd. All rights reserved.