Showing papers on "Flow shop scheduling published in 1976"

Open Shop Scheduling to Minimize Finish Time

Abstract: A linear time algorithm to obtain a minimum finish time schedule for the two-processor open shop together with a polynomial time algorithm to obtain a minimum finish time preemptive schedule for open shops with more than two processors are obtained. It is also shown that the problem of obtaining minimum finish time nonpreemptive schedules when the open shop has more than two processors is NP-complete.

Due dates in job shop scheduling

Abstract: Much of job-shop scheduling research is based on the assumption that due dates are outside the control of the scheduler. The paper examines several procedures for specifying due dates, largely dependent on the expected processing time for jobs and on the level of congestion in the shop. The effect of these procedures is examined in the case of three loading rules (FIFO, St and SI∗) On waiting times, on missing due dates and on notional cost functions. The study is based on numerous simulations of a given shop operating at various levels of load ratio and the case of a fluctuating load is briefly examined.

Scheduling a Project Under Multiple Resource Constraints: A Zero-One Programming Approach

Abstract: An implicit enumeration (zero-one programming) algorithm is described for solving the multiple-constrained resource, project scheduling problem. The algorithm developed takes special advantage of the structure of the zero-one formulation, resulting in a significant decrease in the amount of computation time required to solve a given multi-resource problem. A description of the computer program for implementing the procedures developed is provided, as are detailed computation results. Because the multiple-constrained resource, project scheduling problem subsumes the job-shop scheduling and other related sequencing problems, extensions of our approach to the machine sequencing problem (along with limited computation results) are also reported.

Route Constrained Fleet Scheduling

Abstract: This paper attempts to provide some insight into the structure of a large class of fleet scheduling problems. Scheduling under fixed due date constraints is shown to be easily solved using a new formulation of the problem. Scheduling under flexible due date constraints is shown to be inherently complex, and strong evidence is given for asserting that no efficient polynomial bounded algorithm exists for solving this problem exactly. A fast heuristic approach is described which has worked well in some school bus scheduling applications.

Finding Some Essential Characteristics of the Feasible Solutions for a Scheduling Problem

Abstract: This note is concerned with some essential characteristics of the feasible solutions for a job-shop scheduling problem in which the jobs are constrained by fixed starting times and due dates. These characteristics are related to the scheduling order of operations on each machine and to the fixed starting and completion times for each operation. We present the basic principles enabling one to define these characteristics and propose a procedure for finding them.

Heuristic Scheduling of Activities under Resource and Precedence Restrictions

Abstract: This paper extends the field of heuristic algorithms for resource constrained scheduling problems in three important areas. First, an algorithm is introduced where the role of the heuristic scheduling urgency factor is expanded from one of solely determining the order in which activities are considered for scheduling at a given instant, to one of determining the combination of activities to be scheduled at this instant. Second, a new hybrid scheduling urgency factor capitalizing on the fact that this algorithm is sensitive to the absolute value rather than relative sequence of the urgency factors is introduced. Finally, a systematic approach to the evaluation of such algorithms is introduced. This includes the identification of relevant problem attributes and the adoption of evaluative concepts such as computational efficiency and analytic and systems effectiveness.

Flowshop sequencing problem with ordered processing time matrices: A general case

Abstract: The ordered matrix flow shop problem with no passing of jobs is considered. In an earlier paper, the authors have considered a special case of the problem and have proposed a simple and efficient algorithm that finds a sequence with minimum makespan for a special problem. This paper considers a more general case. This technique is shown to be considerably more efficient than are existing methods for the conventional flow shop problems.

An ordered flow-shop sequencing problem with mean completion time criterion†

Abstract: This paper investigates a subcategory of the classical n job m machine problem in which the processing times of different jobs are ' ordered '. An extremely simple algorithm is presented which obtains a sequence minimizing the mean completion time of all jobs. The proof of optimality is presented in the Appendix. The problem illustratos that although no efficient procedure exists to solve the classical flow-shop problem with the mean completion time criterion, it is possible to develop such a procedure for a specially structured problem.

The production capacity of job shops with limited storage space

Abstract: Suppose the number of jobs which can be stored in front of the machines in a job shop is limited. As a result, arriving jobs for which there is no space in the shop will form a shop queue. The production capacity or maximum departure rate of jobs from the shop will depend on the way in which jobs are selected from the shop queue for release to the machine queues. For a job shop with two identical machines and random routing of jobs a number of release rules are compared. It is shown that the production capacity is increased when the number of jobs in the shop is kept less than the available storage space. Among release rules independent'of job processing times and number of operations the optimum release rule is shown, using dynamic programming, to be the idle machine rule, i.e. only release a job to the shop when a machine would otherwise be idle.

The theory-practice gap in job-shop scheduling

Abstract: This job-shop scheduling problem is perhaps the most common form of industrial scheduling problem, it is also probably the most complex. This paper examines the nature of the problem and reviews the state of the art of scheduling theory and its relevance to the solution of practical problems.

Due-Dates and Instantaneous Load in the One-Machine Shop

Abstract: The due-date assignment problem occurs when due-dates are assigned within, rather than outside, a job shop. This study explores the importance of instantaneous and future shop loads in setting due-dates in shops operating under due-date dependent queue discipline. The assignment of due-dates to arriving jobs in an m-machine shop is formulated as a stochastic dynamic programming problem in the first part of this study. A computational experiment using dynamic programming is performed in the second part and due-dates are developed for specific instantaneous load conditions in a simulated one-machine shop. The importance of instantaneous and future shop loads for assigning due-dates in a one-machine shop, with constant interarrivals and exponential service times, is shown.

Technical Note—Johnson's Three-Machine Flow-Shop Conjecture

Abstract: In an epoch-setting paper on scheduling theory, Johnson determined an efficient algorithm for solving the two-stage flow-shop problem and two special cases of the three-stage problem. In his concluding remarks he suggested another special condition in which one would obtain a three-stage solution. We give an example to show that this conjecture is not quite true. A true statement is obtained, however, by only a slight strengthening of the original. The primary issue concerns the impact of the two-stage no-preference precedent rules on the three-stage problem.

Periodic Job Scheduling in a Distributed Processor System

Abstract: This investigation considers the problem of the nonpreemptive scheduling of a set of independent periodic jobs in a computer system characterized by a collection of processors, memories, and interconnection mechanisms. Such a collection of resources can be used to perform the functions of a process control environment as are found, for example, in the avionics of a military or commercial aircraft. The distribution of these resources permits weight, volume, power, cost, and reliability requirements to be satisfied. Each periodic job is characterized by its frequency and its execution time. The inverse of the frequency, the period, is assumed to be an integer, and the initiation time and the completion time of job must be strictly met. An optimal algorithm is developed for a job set whose members are related by a binary frequency distribution. That is, if the jobs in the set are ordered in terms of decreasing job execution frequency, then fi = 2fi+1. The optimal result is generalized to include conditions in which the jobs are related by fi = kfi+1, where k is an integer.

Two issues in the evaluation of job-shop schedules

Abstract: Two issues are examined concerning the evaluation of job-shop schedules. First, machine and labor cost/utilization are suggested as alternatives to physical utilization criteria. Secondly, an exploration is made of the use of Kiviat Charts as a means of integrating multidimensional criteria for the overall evaluation of the quality of job shop schedules.

A decision-making process for the real time control of a production unit†

Abstract: The scheduling of jobs on machines in a job-shop is considered using a multilevel decision-making structure The levels are coordinated by considering as constraints on one level the decision made on the preceding level For job-shop scheduling a tool is proposed to enable one to find and to analyse the set of feasible schedules in the light of the decision taken on the previous level The information obtained as to the earliest starting and latest finishing times for performing the operations, as well as the logical sequence constraints acts as decision aids for the scheduling of the operations The decision is made by choosing, from amongst the actions which are possible in the light of the overall objective, an action which takes into account secondary elements and considerations particular to the job-shop

On the Computational Complexity of a Generalized Scheduling Problem

Abstract: The parallel scheduling of a partially ordered set of tasks has received great attention. The partially ordered tasks can be viewed as components of a straight-line program. In this note, we discuss some aspects of the nonpreemptive parallel scheduling of a program with more general control structures. We examine the existence of optimal k-processor schedules, and in line with recent interest in the complexity of computer computations and algorithms, we study the complexity of constructing optimal k-processor schedules. In particular we show that, for every k > 1, any algorithm that would yield an optimal k-processor schedule of a loop-free program, when such a schedule exists, will be of exponential-time complexity.

Critical Ratio Scheduling with Queue Waiting Time Information: An Experimental Analysis

Abstract: The Critical Ratio and Slack Time priority scheduling rules have been applied by a number of firms in computer-based scheduling systems for manufacturing operations. One question in using these rules is whether queue waiting time estimates for individual machines should be used in making scheduling decisions. Simulation experiments are reported in this paper that measure the effect of including historical queue time data in the Critical Ratio and Slack Time rules. The results suggest that such data can adversely affect shop performance, measured using criteria such as job flow times, job lateness, and inventory system costs.

Systematic programming of scheduling algorithms

Abstract: This paper applies the technique of systematic (or structured) programming for programming scheduling algorithms as encountered in operating system design. Monitors are used for structuring scheduling algorithms and a synchronizing method is proposed for process scheduling. Some fairly difficult scheduling problems are solved systematically to illustrate the usefulness of the monitor concepts and the synchronizing method. Certain implementation aspects are also discussed.

Job shop scheduling—A case study

Abstract: A missile range is essentially a large-scale job-shop, involving prodigious amounts of test equipment and formidable problems of coordination. Because of its characteristics, a missile range can be considered a one-machine, N-job situation. For this problem the major scheduling methods were examined and tested, but all were discarded as unfeasible except one which used a Monte Carlo scheduling procedure adjoined with statistical stopping rules. An algorithm based on these ideas was constructed, and it has proven to be flexible and workable, providing predictably near optimum schedules for the missile range within a probabilistic and statistical framework. Even though there is not total implementation yet, considerable benefits to the missile range have already been experienced. For example, in order to automate the scheduling process, it was necessary to codify the goals of the range, something that had never been formalized before. This involved an unprecedented scrutiny and precision of definition of these goals, and from this study a reasonable numerical optimization criterion was constructed. Also, in order to use any automated scheduling algorithm, data files had to be stored on tape for ready access, which in turn has improved other operations on the missile range that were dependent on these data. Furthermore, the scheduling algorithm is providing conflict-free schedules in a few minutes of computer time.

Personnel scheduling in public systems: a survey

Abstract: In many public systems efficiencies may be realized by improved personnel scheduling. This paper surveys the literature on personnel scheduling in the public domain. Two general problems are considered: the daily scheduling problem where hourly employee work day patterns are determined and the weekly scheduling problem where day off and day on work week patterns are constructed. The daily problem is discussed in terms of scheduling with and without simultaneous work assignment; and the weekly problem is dichotomized into those schedules based on cyclical personnel requirements and those that are not.

A Series-Parallel Multiple-Criteria Model for a Scheduling Problem in the Dress-Making Industry

Abstract: In industrial scheduling problems, before finding suitable algorithms for solving mathematical programs, one often encounters difficulties in formulation and formalizing the problems themselves. This is especially the case when some optimal control is desired. There are several reasons for this: (a) It is difficult to arrive at a general agreement on defining what are precisely good (or optimal) operating conditions of the manufacturing process. (b) There are generally many criteria and constraints inter-related each to the other in a complex manner. (c) Data are not always available.

A time-sharing interactive program for class scheduling

Abstract: The purpose of this paper is to describe a time-shared class scheduling program that has been implemented and used for the past three years by the Oklahoma City Public Schools. The program uses heuristic procedures in an attempt to minimize student conflicts in a “modified modular scheduling” environment. In addition, the program is interactive so that the scheduler takes an active role in the scheduling decisions.

Simulation as a planning technique for a complex machine shop

Abstract: A deterministic simulation study of a complex machine shop consisting of 69 work centres is presented. The purpose of the simulation study was to develop a planning tool to evaluate effects on overtime, work centre bottlenecks, in-process inventory buildup, delivery delays and other output variables caused by individual part delays of different load mixes, modifications in work centre capacities, installation of more automated machinery, and modification in scheduling rules. The simulation programme and the machine shop it models are described. It was found that the developed simulation programme can be used as a useful planning tool for evaluating short-term and intermediate-term alternatives.