A Generalized Cambridge Ring is a queueing system that can be used
as an approximate model of some material handling systems used in modern
factories. It consists of one or more vehicles that carry cargo from origins
to destinations around a loop, with queues forming when cargo temporarily
exceeds the capacity of the system. For some Generalized Cambridge Rings
that satisfy the usual traffic conditions for stability, it is demonstrated that
some nonidling scheduling polices are unstable. A good scheduling policy
will increase the efficiency of these systems by reducing waiting times and by
therefore also reducing work in process (WIP). Simple heuristic policies are
developed which provide substantial improvements over the commonly used
first-in-first-out (FIFO) policy. Variances are incorporated into previously
developed fluid models that used only means to produce a more accurate
partially discrete fluid mean-variance model, which is used to further reduce
waiting times. Optimal policies are obtained for some simple special cases, and
simulations are used to compare policies in more general cases. The methods
developed may be applicable to other queueing systems. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/6530 |
| Date | 14 October 2009 |
| Creators | Bauer, Daniel Howard |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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