Showing papers on "Job shop scheduling published in 1969"

Multiproject Scheduling with Limited Resources: A Zero-One Programming Approach

Abstract: A zero-one 0-1 linear programming formulation of multiproject and job-shop scheduling problems is presented that is more general and computationally tractable than other known formulations. It can accommodate a wide range of real-world situations including multiple resource constraints, due dates, job splitting, resource, substitutability, and concurrency and nonconcurrency of job performance requirements. Three possible objective functions are discussed; minimizing total throughput time for all projects: minimizing the time by which all projects are completed i.e., minimizing makespan; and minimizing total lateness or lateness penalty for all projects.

A Column Generation Algorithm for a Ship Scheduling Problem

Abstract: This paper describes an algorithm for a ship scheduling problem, obtained from a Swedish shipowning company The algorithm uses the Dantzig-Wolfe decomposition method for linear programming The subprograms are simple network flow problems that are solved by dynamic programming The master program in the decomposition algorithm is an LP problem with only zero-one elements in the matrix and the right-hand side Integer solutions are not guaranteed, but generation and solution of a large number of problems indicates that the frequency of fractional solutions is as small as 1–2 per cent Problems with about 40 ships and 50 cargoes are solved in about 25 minutes on an IBM 7090 In order to resolve the fractional cases, some integer programming experiments have been made The results will be reported in a forthcoming paper

The Influence of Setup Time on Job Shop Performance

Abstract: A job shop was simulated in order to determine the effect of different job priority rules involving setup times on shop performance. The seven priority rules tested were chosen on the basis that they could be implemented by job shop foremen. Assumptions in the simulation model were based on experience with an electronics company and published literature. The study indicates that, for a fully loaded shop, giving priority to be the job with the shortest actual setup time, regardless of its run time, gives the best overall performance result.

A Computer Aided Decision System

Abstract: The use of on-line, real-time computer-based information systems to augment managerial decision making raises interesting and significant questions. In search of operational answers, the authors have developed and conducted experiments with a time-sharing computer model. By modeling the dynamics of a job shop the authors were able both to make use of and to evaluate academic research in job shop scheduling. The authors have devised a specific apportionment of the problem environment which permits users of their information system to explore the effects of various combinations of heuristics and programmed decision rules. The response of over 300 managers and academicians who have participated in the experiments provides evidence of the practicality of such an approach to multi-dimensional, time-variant problem solving.

Job shop scheduling by means of simulation and an optimum-seeking search

Abstract: The paper discusses a job shop simulator designed for use in the scheduling of a set of jobs. The simulator has been implemented in the form of a Fortran program. The simulator can be used in conjunction with a search program that adjusts priority rule parameters in seeking an improved schedule.

Job Shop Scheduling with Regular Batch Arrivals

Abstract: This paper describes a simulation exercise of a hypothetical machine shop consisting of five non-identical machines. Jobs arrive in batches, each job having its own routing and operation time specifications, the average times being normally distributed. Nine alternative loading rules are investigated and the SI rule (the selection of the job with the shortest imminent operation) is found to be the most effective in reducing the mean job throughput time and delay factor, when the batch size is comparatively small. For large batches, however, the results suggest that the SI rule is not the most effective. Ways to reduce the variance of job waiting times are also investigated.

Junction Optimisation Technique

Abstract: where ai} > 0 is the minimum time interval which must elapse between an ordered pair of events of types i and j whether or not there are intermediate events. (5) The last requirement proves to be crucial in railway applications of the kind considered below, and marks the main point of divergence from standard transportation network theory. In its absence, the present problem reduces to a variant of the Travelling Salesman Problem (Reference 1) by regarding events as towns and equating time with distance. We are tacitly assuming in (4) and (5) above that real events have zero duration. In an application when this is not the case, the theory can still be applied by denning theoretical events as, say, the start of corresponding real events, provided that a constraint of the form (5) holds for the starting times. The basic scheduling problem can now be stated in the following form: 'Find a schedule for the events

The current state of research in job shop scheduling

Abstract: The state of the art of job shop research is investigated via the development of a framework within which problems and results may be described The bulk of the paper is devoted to the development of the framework and the research which arises from it Few explicit references are made to the large body of published research on the problem

Further extensions of the tanker scheduling problem

Abstract: : Several modifications to the Dantzig and Fulkerson tanker scheduling problem are described. The original formulation addressed the determination of the minimal number of homogeneous tankers needed to meet a fixed schedule of deliveries. An earlier modification considered an insufficient number of vehicles to make all deliveries and a set of utilities associated with each vehicle delivery. The maximum utility solution to this problem can be found using the Fulkerson out-of kilter algorithm. The paper further extends the vehicle constrained problem to allow a span of feasible delivery times in lieu of a fixed schedule. This extension results in nonintegral valued flows in the network, precluding the application of network algorithms. The concept of a generalized bundle constraint is presented and a column-generation linear programming solution technique is described. The paper considers extensions to a fleet of vehicles with differing characteristics. A solution technique for the multicommodity flow problem is described. (Author)