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Current trends in deterministic scheduling
 ANNALS OF OPERATIONS RESEARCH
, 1997
"... Scheduling is concerned with allocating limited resources to tasks to optimize certain objective functions. Due to the popularity of the Total Quality Management concept, ontime delivery of jobs has become one of the crucial factors for customer satisfaction. Scheduling plays an important role in ac ..."
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Cited by 20 (0 self)
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Scheduling is concerned with allocating limited resources to tasks to optimize certain objective functions. Due to the popularity of the Total Quality Management concept, ontime delivery of jobs has become one of the crucial factors for customer satisfaction. Scheduling plays an important role in achieving this goal. Recent developments in scheduling theory have focused on extending the models to include more practical constraints. Furthermore, due to the complexity studies conducted during the last two decades, it is now widely understood that most practical problems are NPhard. This is one of the reasons why local search methods have been studied so extensively during the last decade. In this paper, we review briefly some of the recent extensions of scheduling theory, the recent developments in local search techniques and the new developments of scheduling in practice. Particularly, we survey two recent extensions of theory: scheduling with a 1jobonrmachine pattern and machine scheduling with availability constraints. We also review several local search techniques, including simulated annealing, tabu search, genetic algorithms and constraint guided heuristic search. Finally, we study the robotic cell scheduling problem, the automated guided vehicles scheduling problem, and the hoist scheduling problem.
Scheduling with Unexpected Machine Breakdowns
, 1998
"... We investigate an online version of a basic scheduling problem where a set of jobs has to be scheduled on a number of identical machines so as to minimize the makespan. The job processing times are known in advance and preemption of jobs is allowed. Machines are noncontinuously available, i.e., the ..."
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Cited by 12 (0 self)
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We investigate an online version of a basic scheduling problem where a set of jobs has to be scheduled on a number of identical machines so as to minimize the makespan. The job processing times are known in advance and preemption of jobs is allowed. Machines are noncontinuously available, i.e., they can break down and recover at arbitrary time instances not known in advance. New machines may be added as well. Thus machine availabilities change online. We first show that no online algorithm can construct optimal schedules. We also show that no online algorithm can achieve a bounded competitive ratio if there may be time intervals where no machine is available. Then we present an online algorithm that constructs schedules with an optimal makespan of C OPT max if a lookahead of one is given, i.e., the algorithm always knows the next point in time when the set of available machines changes. Finally we give an online algorithm without lookahead that constructs schedules with a nearly opt...
Preemptive Scheduling with Variable Profile, Precedence Constraints and Due Dates
 Discrete Applied Mathematics
, 1993
"... This paper is concerned with the problem of scheduling preemptive tasks subject to precedence constraints in order to minimize the maximum lateness and the makespan. The number of available parallel processors is allowed to vary in time. It is shown that when an Earliest Due Date first algorithm pro ..."
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Cited by 9 (2 self)
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This paper is concerned with the problem of scheduling preemptive tasks subject to precedence constraints in order to minimize the maximum lateness and the makespan. The number of available parallel processors is allowed to vary in time. It is shown that when an Earliest Due Date first algorithm provides an optimal nonpreemptive schedule for unitexecution time (UET) tasks, then the preemptive priority scheduling algorithm, referred to as Smallest Laxity First, provides an optimal preemptive schedule for realexecutiontime (RET) tasks. When the objective is to minimize the makespan, we get the same kind of result between Highest Level First schedules solving nonpreemptive tasks with UET and the Longest Remaining Path first schedule for the corresponding preemptive scheduling problem with RET tasks. These results are applied to four specific profile scheduling problems and new optimality results are obtained. Keywords: Preemptive Scheduling, List Schedule, Priority Schedule, Variable P...
Scheduling of Jobs and Maintenance Activities on Parallel Machines
 35 th International Conference on Computers and Industrial Engineering
, 2000
"... Most machine scheduling models assume that the machines are available all the time. However, in many realistic situations, machines need to be maintained and hence may become unavailable during a certain period. In this paper, we study the problem of processing a set of jobs on parallel machines in ..."
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Cited by 9 (1 self)
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Most machine scheduling models assume that the machines are available all the time. However, in many realistic situations, machines need to be maintained and hence may become unavailable during a certain period. In this paper, we study the problem of processing a set of jobs on parallel machines in which each machine must be maintained once in the planning horizon. Our objective is to schedule jobs and maintenance activities so that total weighted completion time of jobs is minimized. Two cases are studied in this paper. In the first case, there is a sufficient amount of resource and hence different machines can be maintained simultaneously if necessary. In the second case, only one machine can be maintained at any given time. In this paper, we first show that, even when all the jobs have the same weight, both cases of the problem are NPhard. We then propose branch and bound algorithms based on the column generation approach for solving both cases of the problem. The algorithms are ca...
Profile Scheduling by List Algorithms
, 1994
"... The notion of profile scheduling was first introduced by Ullman in 1975 in the complexity analysis of deterministic scheduling algorithms. In such a model, the number of processors available to a set of tasks may vary in time. Since the last decade, this model has been used to deal with systems subj ..."
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The notion of profile scheduling was first introduced by Ullman in 1975 in the complexity analysis of deterministic scheduling algorithms. In such a model, the number of processors available to a set of tasks may vary in time. Since the last decade, this model has been used to deal with systems subject to processor failures, multiprogrammed systems, or dynamically reconfigured systems. The aim of this paper is to overview optimal polynomial solutions for scheduling a set of partially ordered tasks in these systems. Particular attentions are given to a class of algorithms referred to as list scheduling algorithms. The objective of the scheduling problem is to minimize either the maximum lateness or the makespan. Results on preemptive and nonpreemptive deterministic scheduling, and on preemptive stochastic scheduling, are presented.
Machine Scheduling with Availability Constraints
, 1999
"... In most scheduling literature the continuous availability of machines is assumed. However, in real world applications, this may not be the case. The machine may not be available during certain time periods due to deterministic or stochastic reasons. In this paper, the machine scheduling with availab ..."
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In most scheduling literature the continuous availability of machines is assumed. However, in real world applications, this may not be the case. The machine may not be available during certain time periods due to deterministic or stochastic reasons. In this paper, the machine scheduling with availability constraints for both deterministic and stochastic cases will be analyzed. The existing literature will be reviewed.
Machine Scheduling Performance with Maintenance and Failure
"... In manufacturing control, machine scheduling research has mostly dealt with problems either without maintenance or with deterministic maintenance when no failure can occur. This can be unrealistic in practical settings. In this work, an experimental model is developed to evaluate the effect of corre ..."
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In manufacturing control, machine scheduling research has mostly dealt with problems either without maintenance or with deterministic maintenance when no failure can occur. This can be unrealistic in practical settings. In this work, an experimental model is developed to evaluate the effect of corrective and preventive maintenance schemes on scheduling performance in the presence machine failure where the scheduling objective is to minimize schedule duration. We show that neither scheme is clearly superior, but that the applicability of each depends on several system parameters as well as the scheduling environment itself. Further, we show that parameter values can be chosen for which preventive maintenance does better than corrective maintenance. The results provided in this study can be useful to practitioners and to system or machine administrators in manufacturing and elsewhere.
Scheduling jobs on open shops with limited machine availability
 RAIRO Oper. Res
, 1997
"... Abstract. In this paper, open shop scheduling problems with limited machine availability are studied. Such a limited availability of machines may appear in many reallife situations, e.g. as preventive maintenance activities. Three types of jobs are distinguished: nonpreemptable, resumable and preem ..."
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Abstract. In this paper, open shop scheduling problems with limited machine availability are studied. Such a limited availability of machines may appear in many reallife situations, e.g. as preventive maintenance activities. Three types of jobs are distinguished: nonpreemptable, resumable and preemptable. An operation of a resumable job if not completed before a nonavailability period of a machine may be suspended and continued without additional cost when the machine becomes available. In the paper, results are given for the scheduling problems associated with the three types of jobs. For preemptable jobs polynomialtime algorithms based on the twophase method are proposed.
5.1.1 Identical Processors
"... This chapter is devoted to the analysis of scheduling problems in a parallel processor environment. As before the three main criteria to be analyzed are schedule length, mean flow time and lateness. Then, some more developed models of multiprocessor systems are described, imprecise computations and ..."
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This chapter is devoted to the analysis of scheduling problems in a parallel processor environment. As before the three main criteria to be analyzed are schedule length, mean flow time and lateness. Then, some more developed models of multiprocessor systems are described, imprecise computations and lot size scheduling. Corresponding results are presented in the four following sections. 5.1 Minimizing Schedule Length In this section we will analyze the schedule length criterion. Complexity analysis will be complemented, wherever applicable, by a description of the most important approximation as well as enumerative algorithms. The presentation of the results will be divided into subcases depending on the type of processors used, the type of precedence constrai^fer^nd to a lesser extent task processing times and the possibility of task preemption.
Scheduling with Limited Processor Availability
"... In scheduling theory the basic model assumes that all machines are continuously available for processing throughout the planning horizon. This assumption might be justified in some cases but it does not apply if certain maintenance requirements, breakdowns or other constraints that cause the machine ..."
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In scheduling theory the basic model assumes that all machines are continuously available for processing throughout the planning horizon. This assumption might be justified in some cases but it does not apply if certain maintenance requirements, breakdowns or other constraints that cause the machines not to be available for processing have to be considered. In this chapter we discuss results related to deterministic scheduling problems where machines are not continuously available for processing. Examples of such constraints can be found in many areas. Limited availabilities of machines may result from preschedules which exist mainly because most of the real world resources planning problems are dynamic. A natural approach to cope with a dynamic environment is to trigger a new planning horizon when the changes in the data justify it. However, due to many necessities, as process preparation for instance, it is mandatory to take results of earlier plans as fixed which obviously limits availability of resources for any subsequent plan. Consider e.g. ERP (Enterprise Resource Planning) production planning systems