Showing papers on "Fair-share scheduling published in 1981"

Complexity of vehicle routing and scheduling problems

Abstract: The complexity of a class of vehicle routing and scheduling problems is investigated. We review known NP-hardness results and compile the results on the worst-case performance of approximation algorithms. Some directions for future research are suggested. The presentation is based on two discussion sessions during the Workshop to Investigate Future Directions in Routing and Scheduling of Vehicles and Crews, held at the University of Maryland at College Park, June 4–6, 1979.

A Review of Production Scheduling

Abstract: Production scheduling can be defined as the allocation of available production resources over time to best satisfy some set of criteria. Typically, the scheduling problem involves a set of tasks to be performed, and the criteria may involve both tradeoffs between early and late completion of a task, and between holding inventory for the task and frequent production changeovers. The intent of this paper is to present a broad classification for various scheduling problems, to review important theoretical developments for these problem classes, and to contrast the currently available theory with the practice of production scheduling. This paper will highlight problem areas for which there is both a significant discrepancy between practice and theory, and for which the practice corresponds closely to the theory.

Some scheduling techniques and an easily schedulable horizontal architecture for high performance scientific computing

Abstract: Horizontal architectures are attractive for cost-effective, high performance scientific computing. They are, however, very difficult to schedule. Consequently, it is difficult to develop compilers that can generate efficient code for such architectures. The polycyclic architecture has been developed specifically to make the task of scheduling easy. As a result, it has been possible to develop a powerful scheduling algorithm that yields optimal and near-optimal schedules for iterative computations. This novel architecture and this scheduling algorithm are the topic of this paper.

Optimal assignment of due-dates for a single processor scheduling problem

Abstract: Given processing times of n jobs on a single machine with penalties for earliness and tardiness and penalties associated with assignment of due-dates, the objective is to select optimal due-dates and optimal sequence. Scheduling procedure for the solution of this problem is presented along with proof of optimality and illustrative numerical examples.

The state of the art in the routing and scheduling of vehicles and crews

Abstract: This study rests on a fundamental consideration in the distribution of goods, namely, the determination of the most effective and efficient way to transport goods from plant to warehouses to customers. The main focus of this study is on vehicle/crew routing and scheduling. Related problems such as location, districting, and clustering are not discussed in detail. This report presents the state of the art in routing and scheduling of vehicles and crews. It discusses the theoretical bases surrounding many of the problems, and describes in detail many routing and scheduling applications. The report provides a classification of routing and scheduling problems according to their underlying characteristics; discusses many of the issues in implementation; and includes a comprehensive bibliography of references (more than 500 citations) relating to routing and scheduling. This report also presents conclusions and future research topics that include 1) a discussion of the prospects for using routing and scheduling models within real-world settings, and 2) a list of possible directions of future research in the area of routing and scheduling. The authors state that organizations are just starting to realize the potential for savings resulting from the automation of their routing and scheduling activities. They also advocate the development of general purpose computer software systems that would include a flexible interactive user interface, and a data-base system that is easy to understand and manipultate. (UMTA)

A Multiple Objective Nurse Scheduling Model

Abstract: The authors present a model for the nurse scheduling problem which works in two phases. In the first phase, the nurses are assigned their day-on/day-off pattern for the two-week scheduling horizon by a goal programming model which allows for consideration of the multiple conflicting objectives inherent in scheduling a nursing staff. The second phase makes specific shift assignments through the use of a heuristic procedure. The two-phase approach results in considerable reductions in problem size, thus reducing the solution effort. Extensions to the basic model are also examined.

A Guaranteed-Accuracy Round-off Algorithm for Cyclic Scheduling and Set Covering

Abstract: The problem of cyclic staff scheduling is solved by a linear programming round-off heuristic for which a bound on the absolute error is established. The quality of the bound is independent of the resource requirements. Moreover, the quality of the bound improves as the matrix of resource availability approximates the property of consecutive ones. The appropriateness of the heuristic is further established by showing that cyclic staff scheduling is NP-complete.

On Single-Machine Scheduling with Precedence Relations and Linear or Discounted Costs

Abstract: Some results of Sidney (Sidney, J. B. 1975. Decomposition algorithms for single machine sequencing with precedence relations and deferral costs. Opns. Res. 23 283–298.) concerning order-constrained...

One machine scheduling problem with dual criteria

Abstract: DUAL CRJ:TERIA Shigeji Miyazaki University of Osaka Prefecture (Received January 12, 1980; Revised August 28,1980) In this paper we deal with a one machine scheduling problem to minimize the mean weighted flow·time subject to the constraint that the job tardiness is not greater than a specified value. An algorithm to obtain. a pair· wise local optimum schedule for this problem has been pres,ented by Smith [4]. We give a necessary condition under which a pairwise local optimum schedule should not coincide with the global optimum one, and give an inlproved schedule for this cas,e. On the basis of the analysis, an efflcient algorithm is developed to obtain global optimum schedules for more cases than Smith's algorithm. Computational experiment is performed to show the quality of the solution, the computational time, and core memory size required for the algorithm in comparison with the previous three algorithms: Smith's, Bums', and DP.

Computational results for very large air crew scheduling problems

Abstract: The airline crew scheduling problem is typically formulated as a set covering problem. The Federal Express Corporation has recently implemented a heuristic crew scheduling system based on this model. The system has been implemented on an IBM 3033 computer. Computational results are presented for crew scheduling problems with up to 3000 rows and 15,000 columns. Results of operational quality are obtained in less than one hour of computer time. This model provides a prototype for a wide variety of large scale crew scheduling applications.

An investigation of the advantages of using a man-computer interactive scheduling methodology for job shops

Abstract: Scheduling has been a difficult problem for job shops which manufacture discrete parts. The research described in this paper investigates the hypothesis that interactive man-computer scheduling methodology is more effective in this task than a batch scheduling methodology. This hypothesis is investigated under eight different problem configurations generated by varying three job description parameters. The results have been evaluated statistically and the effectiveness of an interactive schedule compared to the slack-per-remaining-operation heuristic is investigated. Influences of the level of variation in job description parameters on the quality of the interactive schedule have also been analysed in this study. Results show that scheduling interactively is significantly more effective in most problem situations, and that the level of variation of some of the parameters has a significant impact on the quality of the interactive schedule.

On Optimal Scheduling Algorithms for Time-Shared Systems

Abstract: The problem of fmdlng those optimum scheduling algorithms for time-shared systems that mlmmize a cost function that depends on waiting time and required service time IS considered An optimality condmon which sometimes leads to infeasible algorithms is established The procedure is unproved upon by use of a mathematical programming technique but still does not always generate feasible algorithms. These results are used as upper bounds on the performance of known feasible algorithms so that it is possible to evaluate how close to optimal the present algorithms come.

Binary trees and parallel scheduling algorithms

Abstract: This paper examines the use of binary trees in the design of efficient parallel algorithms. Using binary trees, we develop efficient algorithms for several scheduling problems. The shared memory model for parallel computation is used. Our success in using binary trees for parallel computations, indicates that the binary tree is an important and useful design tool for parallel algorithms.

Crane Scheduling Problems

Abstract: Crane scheduling problems are introduced together with a descriptive general model. In particular, crane scheduling problems with one operation per job are investigated when arrival patterns are static or dynamic and when the processing times are arbitrary.

Vampires and tasc: two successfully applied bus scheduling programs. from the book computer scheduling of public transport

Abstract: Two bus scheduling programs are described; both have been used in practical situations. The earlier and more powerful program, VAMPIRES, consistently leads to savings of five per cent or more in vehicle numbers. TASC is a simpler program, easier to understand and use, which does not apparently achieve as much. Recent experience is that the simpler program is more acceptable to bus operators.

Hastus i: a mathematical programming approach to the bus driver scheduling problem. from the book computer scheduling of public transport

Abstract: This paper presents a mathematical programming formulation of the bus driver scheduling problem in a transit company. A relaxation of the problem and a solution strategy are described. The implementation and results obtained in Quebec City are briefly overviewed.

Bounds on Schedules for Independent Tasks with Similar Execution Times

Abstract: An open problem by Graham is solved. The problem considered is that of scheduling a set of n independent tasks nonpreemptively on m identical processors to minimize finish time. Let a.,o and ~o be the finish times of an optimal schedule and an arbitrary list schedule, respectively. The worst possible behavior of o~/w0 for tasks with similar execution times is investigated.

Experimentation with a computerized system for scheduling mass transit vehicles and crews. from the book computer scheduling of public transport

Abstract: An interactive model is proposed for simultaneous solution of the vehicle and driver scheduling problems. A non-interactive version has been programmed and has achieved results which compare favorably on test data with those achieved by manual methods. The model uses a network representation of the problem, and schedules are built up from the network using a series of matching processes.

Myopic heuristics for single machine scheduling problems

Abstract: For many years difficult combinatorial problems, such as scheduling problems, have been solved by the practitioner with heuristics. We suggest in this paper how to determine for which problems heuristics should be developed and, for a class of these problems, how to develop these procedures naturally. These results are motivated by theoretical results in computer science. The suggestion is numerically tested on a particular single machine scheduling problem.

Distributed task force scheduling in multi-microcomputer networks

Abstract: Efficient task scheduling techniques are needed for microcomputer networks to be used as general purpose computers. The Wave Scheduling technique, developed for the MICRO-NET network computer, co-schedules groups of related tasks onto available network nodes. Scheduling managers are distributed over a logical control hierarchy. They subdivide requests for groups of free worker nodes and send waves of requests towards the leaves of the control hierarchy, where all workers are located. Because requests from different managers compete for workers, a manager may have to try a few times to schedule a task force. Each task force manager actually requests slightly more workers than it really needs. It computes a request size which minimizes expected scheduling overhead, as measured by total idle time in worker nodes. Using a Markov queueing model, it is shown that Wave Scheduling in a network of microcomputers is almost as efficient as centralized scheduling.

A branch and bound network algorithm for interactive process scheduling

Abstract: A multi-facility multi-product production scheduling problem is considered in terms of a general class of process unit operations scheduling problems which are common in the refining and chemicals processing industries. A generalized network formulation is used to model the conversion of unit processing capacity to finished products. A specialized branch and bound algorithm is used to enforce the restriction that only one operation can be run per unit at any given time. The algorithm minimizes total costs, which consist of unit operating costs, processing costs, inventory holding costs, setup and changeover costs. A procedure is developed by which the setup and changeover costs are used to estimate bounds for the network model in the branch and bound algorithm. All other costs are incorporated in the network formulation. It is shown that the algorithm is more efficient in those problems for which the setup and changeover costs are small, or in problems in which a lower bound for the setup and changeover costs can be accurately estimated. The implementation of the algorithm in an interactive process scheduling system is discussed in terms of the human engineering factors involved.

M/G/1 Queues with Scheduling within Generations and Removable Server

Abstract: Two models of M/G/1 queues with removable server and scheduling within generations are considered in this paper. The scheduling policy considered here is the shortest processing time; the control policies are the multiple vacations policy and N-control policy. The Laplace-Stieltjes transforms of the waiting time distribution, the mean cost rates and the optimal control policies are derived for these two models. Properties of the delayed busy cycle are used in our analysis.

An introduction to multiprocessor scheduling

Abstract: This is a tutorial survey of recent results in the area of multiprocessor scheduling. Computational complexity theory provides the framework in which these results are presented. They involve on one hand the development of new polynomial optimization algorithms, and on the other hand the application of the concept of NP-hardness as well as the analysis of approximation algorithms