Showing papers on "Flow shop scheduling published in 1974"

A Loading and Balancing Methodology for Job Shop Control

Abstract: An algorithmic procedure is devised for loading and releasing work to a job shop environment. The objective of the procedure is the control and balance of workloads in the shop. The importance of s...

Two machine flow shop scheduling problems with sequence dependent setup times: A dynamic programming approach

Abstract: This paper considers the two different flow shop scheduling problems that arise when, in a two machine problem, one machine is characterized by sequence dependent setup times. The objective is to determine a schedule that minimizes makespan. After establishing the optimally of permutation schedules for both of these problems, an efficient dynamic programming formulation is developed for each of them. Each of these formulations is shown to be comparable, from a computational standpoint, to the corresponding formulation of the traveling salesman problem. Then, the relative merits of the dynamic programming and branch and bound approaches to these two scheduling problems are discussed.

Job Shop Scheduling with Due Dates and Variable Processing Times

Abstract: A multi-pass heuristic scheduling procedure developed for job scheduling problems with deterministic processing times is tested with processing times that are random variables. The heuristic procedure, which uses expected processing times, typically generates a delay schedule (i.e., a schedule in which some operations are delayed while the machine to process these operations is kept idle awaiting the arrival of another operation). Simulation is employed to compare the performance of the schedule generated by the heuristic procedure, a nondelay transformation of that schedule, and the nondelay schedules obtained with four single-pass dispatching rules. The criteria employed are fraction of jobs tardy, mean tardiness, variance of tardiness, and maximum tardiness. The delay schedule produced by the heuristic procedure was found to be markedly superior under certain conditions. Under other conditions, the relative performance of the scheduling rules appears highly problem dependent. Implications of these resu...

Minimizing Mean Flowtime in the Flow Shop with No Intermediate Queues

Abstract: This paper deals with the flow shop model in which no intermediate job queues are permitted. A branch and bound algorithm for minimizing mean flowtime is developed and detailed computational experience is reported. Experimental results suggest that this problem can be solved as readily as the makespan problem in the traditional flow shop model.

An Almost-Optimal Algorithm for the Assembly Line Scheduling Problem

Abstract: This paper considers a solution to the multiprocessor scheduling problem for the case where the ordering relation between tasks can be represented as a tree. Assume that we have n identical processors, and a number of tasks to perform. Each task T i requires an amount of time μ i to complete, 0 i ≤ k, so that k is an upper bound on task time. Tasks are indivisible, so that a processor once assigned must remain assigned until the task completes (no preemption). Then the "longest path" scheduling method is almost-optimal in the following sense.

Optimal scheduling of independent tasks on heterogeneous computing systems

Abstract: In this paper, the problem of optimal scheduling of independent tasks on heterogeneous computing systems is considered. Optimal scheduling algorithms which produce preemptive schedules with minimal completion times and non-preemptive schedules with minimal mean flow times are described. A bound on mean flow times also provides us with information concerning the relative merit of different multiprocessor systems.

Job Shop Scheduling with Due Dates and Overtime Capability

Abstract: A scheduling procedure is proposed for the static job shop problem with job due dates and overtime capability. An example is used to demonstrate the procedure and the generation of trade-off curves relating overtime and total tardiness for use in managerial evaluation of alternative schedules. Results are reported for a set of trial problems having 30 to 98 processing operations. An extension of the procedure is described for dynamic job shop scheduling.

An Implicit Enumeration Algorithm for the Nonpreemptive Shop Scheduling Problem

Abstract: The purpose of this paper is to report on the development and computational results of an implicit enumeration algorithm for the nonpreemptive shop scheduling problem. This algorithm is inspired by the disjunctive graph representation of the problem and is somewhat similar to the branch-and-bound approach. In order to guide the search, the algorithm employs a decision vector which is designed to reduce the number of iterations. Attention has been focused on improving the quality of the initial solution with minimum computational effort involved. The rapid convergence of the algorithm is demonstrated by solving problems with up to 1000 operations. The results obtained are compared favorably with a number of published procedures. Generalizations of the algorithm are also provided.

Scheduling Unit-Time Tasks with Limited Resources

Abstract: A set of tasks are to be scheduled on a multiprocessing system with s resources. Each task takes one unit time to complete, and requires certain amounts of resources. The schedule is to be consistent with a prescribed partial order relation on the task, and the total demand for each resource must not exceed a fixed amount at any instant. In this paper we analyze the worst-case behavior of several heuristic scheduling algorithms.

A Hierarchical Approach for a Naval Tender Job Shop Design.

Abstract: : A hierarchical approach for the determination of the manpower and machinery configuration for a naval tender machine shop is presented. The application of numerically controlled machine technology is stressed. A mixed integer programming model is developed to support aggregate decisions regarding machinery and manpower allocations. The job shop performance under the suggested aggregate characteristics is tested by a detailed simulation model. An iterative procedure links both models to ensure satisfactory overall performance. A typical naval tender machine shop workload is used in the model implementation. (Author)

Evaluation of various scheduling disciplines by computer systems

Abstract: The assignment of patients to examination rooms in a diagnostic radiology department can be categorized as a job-shop scheduling problem. This paper shows a way of using a GPSS (General Purpose Simulation System) discrete event simulation model to test, analyze and find the best heuristic scheduling algorithms that can be applied to patient flow in a diagnostic radiology department. Four main measures of performance are considered; waiting time before examination, total time in the system, utilization of staff and equipment, and the number of patients in the system at the end of a working day. Among the scheduling disciplines tested include the following six; smallest number of patients in each queue, smallest work load in each queue, shortest processing time (SPT), truncated SPT (with priorities), common queue (patients join a single queue versus multiple queues based on examination type), and truncated common queue. Numerical data of Temple University's Radiology Department are included, and results indicate that two scheduling disciplines are superior to the others. Finally, a feasibility study of implementing the findings with and without a computer are discussed.

Batch computer scheduling: A heuristically motivated approach

Abstract: Efficient scheduling of jobs for computer systems is a problem of continuing concern. The applicability of scheduling methodology described in the operations research literature is severely restricted by the dimensionality of job characteristics, the number of distinct resource types comprising a computer system, the non-deterministic nature of the system due to both interprocess interaction and contention, and the existence of a multitude of constraints effecting job initiation times, job completion times, and job interactions. In view of the large number of issues which must be considered in job scheduling, a heuristic approach seems appropriate. This paper describes an initial implementation of such an approach based upon a fast, analytically driven, performance prediction tool.

A Linear Program for Economic Lot Sizes using Labor Priorities

Abstract: This paper presents the development of a mathematical model to generate economic lot sizes, on a weekly basis, for an assembly-type shop. The model appears as a linear program which optimizes assigned labor priorities. Included is a description of the results achieved from a successful implementation of the model into the assembly operations. The paper also identifies this shop's problem within the general context of multi-product, multi-period scheduling. In particular, a certain class of scheduling problems is formulated using described techniques.

Schedule—constrained job scheduling in a multiprogrammed computer system

Abstract: The schedule-constrained job scheduling problem is defined as the problem of deciding what jobs should co-exist in the memory of a multiprogrammed computer to insure satisfactory schedule performance and adequate resource utilization. At the present time, the job scheduling function in many multiprogrammed computer systems is being accomplished in a suboptimal manner. In computer installations that must pay strict attention to schedule performance, the scheduling module of the operating system, because it does not consider schedule constraints, cannot be allowed to schedule jobs as they beome available for processing. Instead, human judgment must override the operating system by deciding which jobs should be input to the computer. To solve the schedule-constrained job scheduling problem, the author has developed and tested seven scheduling algorithms using a digital simulation model.

A note on steady-state results in queueing and job-shop scheduling:

Abstract: Most queueing models are based on assumptions of steady-state conditions, and most solutions of mathematical models in this field are almost entirely concerned with steady-state conditions. Elaborate queueing models (such as job-shop models) are not amenable to analytical solutions, and investigators have therefore to resort to simulation. The main objective, however, is still to derive values for such variables as the average waiting time and the average queue length that may be expected in the long run. In practice, obtaining this information may require long simulation exercises.

A Model for Predicting the Performance of a Job Shop

Abstract: This paper is concerned with presenting a method of modelling a job shop based on queueing theory. The model is very flexible and may be used to explore the relationships between the resources available in the shop (numbers and characteristics of machines, manpower levels and skills), the workload in the shop, the mode of operation of the shop (labour allocation and priority schemes) and the resulting level of congestion within the shop.

The scheduling of multiple disk drives

Abstract: Techniques for scheduling disk drives are of two types: those which schedule transfers (based on rotational position) and those which schedule seeks (based on cylinder position). A simulation model has been developed to evaluate both of these approaches in a multiple drive environment. Use of this model for a comparison of two techniques for transfer scheduling has recently been reported [13]. This paper presents additional results of that study and extends it with a preliminary exploration of seek scheduling effects. The results indicate that seek scheduling can be effective for large configurations only when used in conjunction with a transfer scheduling technique.