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David R. Alexander I. M. Premachandra Toshikazu Kimura 《Annals of Operations Research》2010,181(1):641-659
This paper analyzes the synchronization process of an assembly-like queueing system in which two distinct types of items/customers
arrive at separate buffers, according to independent Poisson processes, so as to be synchronized into pairs at a synchronization
node. Once a pair is synchronized it then queues up for service from a single server on a first-in-first-out basis as pairs.
It is assumed that the service times of pairs are exponentially distributed and that the system has infinite capacity. Despite
their practical significance, such queueing systems have not been adequately treated in the literature due to their transience
or null recurrence. We first investigate the transient and asymptotic properties of the synchronization process’ first two
moments, both analytically and numerically. Motivated by the observed asymptotic behavior, we then propose an M/M/1 approximation to describe the behavior of such assembly-like queueing systems. Finally, a numerical study of the proposed
approximation reveals that it performs sufficiently well for practical applications. 相似文献
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J. Premachandra C. Kumudinie W. Zhao J. E. Mark T. D. Dang J. P. Chen F. E. Arnold 《Journal of Sol-Gel Science and Technology》1996,7(3):163-175
Hybrid organic-inorganic composites were prepared by precipitating silica into hydroxypolybenzoxazole (HPBO) and sulfopolybenzobisthiazole (SPBT) polymers, with interfacial bonding between the phases improved by use of isocyanatopropyltriethoxy silane and N, N-diethylaminopropyltrimethoxy silane, respectively. The materials were transparent, and scanning electron micrographs indicated a uniform distribution of silica particles of domain sizes less than 1 m. Values of the tensile modulus and tensile strength of the HPBO-silica composites were found to increase with the silica content. Values of the modulus of the SPBT-silica composites also increased in this manner, but the improvements in tensile strength were nearly independent of the amount of silica. The composites exhibited thermal decomposition temperatures of approximately 400–500°C, and the thermal stability was significantly increased for both HPBO and SPBT materials with increase in silica content. The water absorption amount for both types of composites decreased significantly compared to that of the pure polymers, suggesting excellent weatherability. 相似文献
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