Browsing by Subject "Parallel machine"

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    Parallel machine scheduling with flexible resources
    (2012) Edis E.B.; Oguz C.
    Parallel machine flexible resource scheduling (PMFRS) problems consider an additional flexible resource (e.g. operators), which can be freely allocated to any jobs and/or any machines and may speed-up the process in proportion to its amount. If job-machine assignment is unspecified, the problem is referred to as unspecified PMFRS (UPMFRS). This paper reviews the mathematical models of both PMFRS and UPMFRS problems in the literature and not only gives some extensions to the model of dynamic PMFRS problem but also presents integer programming (IP) models for static and dynamic UPMFRS problems with the objective of minimizing makespan. To solve large-sized dynamic PMFRS and UPMFRS problems, a relaxed IP based constraint programming (CP) approach is also proposed. All IP models and the proposed IP/CP approach are tested with an extensive computational study. The results of the computational experiments are discussed with respect to the major parameters of the problem and conclusions are drawn. © 2012 Elsevier Ltd. All rights reserved.
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    Solution approaches for simultaneous scheduling of jobs and operators on parallel machines; [Paralel makinelerde işlerin ve makine operatörlerinin birlikte çizelgelenmesi problemine çözüm yaklaşimlari]
    (2012) Edis E.B.; Oǧuz C.; Özkarahan I.
    In literature, most of the studies related to parallel machine scheduling problems assume that jobs require only machines as the processing resources and accordingly deal with simply job-machine scheduling problem. However, in real-life manufacturing environments, jobs may also require additional resources. A common example of additional resources is cross-training workers that perform tasks related with different machines. This study handles a real-life problem that requires simultaneous scheduling of jobs and operators over the parallel machines. Operators are responsible for monitoring the machines, unloading the parts and trimming extra material. These tasks may not require an operator's full attention during the processing of a job at one machine. In this context, a significant distinguishing feature of the investigated problem is that an operator can be assigned to more than one machine through the specified time periods. While determining the machines that an operator has to deal with during the same scheduling periods, the physical closeness of the machines should also be taken into account. For the problem on hand, with the aim of minimizing the completion time of the last job, integer and constraint programming models have been developed. The models have been evaluated through the test problems with different parameters, and their performances have been discussed. Finally, the applicability of the proposed constraint programming model on the real-life problem has been shown.
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    Parallel machine scheduling with additional resources: Notation, classification, models and solution methods
    (Elsevier B.V., 2013) Edis E.B.; Oguz C.; Ozkarahan I.
    Majority of parallel machine scheduling studies consider machine as the only resource. However, in most real-life manufacturing environments, jobs may require additional resources, such as automated guided vehicles, machine operators, tools, pallets, dies, and industrial robots, for their handling and processing. This paper presents a review and discussion of studies on the parallel machine scheduling problems with additional resources. Papers are surveyed in five main categories: machine environment, additional resource, objective functions, complexity results and solution methods, and other important issues. The strengths and weaknesses of the literature together with open areas for future studies are also emphasized. Finally, extensions of integer programming models for two main classes of related problems are given and conclusions are drawn based on computational studies. © 2013 Elsevier B.V. All rights reserved.