Browsing by Subject "Lot Streaming"
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Item Open Access Lot streaming in flow shops(Bilkent University, 1994) Topaloğlu, EnginLot streaming is permitting partial transfer of processed portions of a job to downstream machines, thus allowing ovelapping operations. The primary motivation is to improve the measures of performance by the quick movement of work in the shop. In this thesis, we study various forms of the lot streaming problem in flow shops to derive the characteristics of optimal solutions. We first analyze single job lot streaming problems, then extend the results to multi-job problems. When there is a single job, the lot streaming problem is to find the best transfer batch sizes that optimizes the given criterion. We consider three different measures of performance, job, sublot and item completion time criteria. We derive a closed form solution for a special case of job completion time criterion. Under sublot completion time criterion, when the first machine has the largest processing time, we show that partial transfers of equal size are optimal. We propose two polynomial time algorithms for the problem in which only two transfer batches are permitted between each consecutive machines for sublot and item completion time criteria. In multi-job lot streaming problems, the sequencing and lot streaming decisions must be considered simultaneously. For multi-job problems we investigate the hierarchical application of lot streaming and sequencing decisions.Item Open Access Lot streaming in multi stage shops(Bilkent University, 1994) Şen, AlperIn this thesis, a number of lot streaming problems in flow, open and job shops are investigated. Lot streaming is the process of splitting a job to allow for overlapping of its operations on various machines resulting in shorter completion times. When there is a single job, the problem is to find the size of the transfer batches (“sublots”) which minimizes a given performance measure (e.g., makespan, mean flow time). Multi-job problems are harder, since sequencing and sizing decisions must be made simultaneously. Most of the current research in lot streaming is concerned with minimum makespan problems in flow shops. In this study, other performance measures and shop structures are also analyzed. Optimal sublot sizes are derived for the single job two machine flow shop mean flow time problem. Solution methods are proposed for the minimum makespan problem in open shops both for multiple job and single job cases.Item Open Access Lot streaming in open shops(Elsevier, 1998-10) Sen, A.; Benli, O.We study lot streaming in shops in which the order the jobs are to be processed is immaterial. For a single job case, the properties of the optimal routing is determined. For the multi job case, two machine shops are analyzed. It is shown that lot streaming will improve makespan only if there is a job with large processing times. We show that there can be at most one such job and derive the optimal sublot sizes and their sequence. c 1999 Elsevier Science B.V. All rights reserved.