Browsing by Author "Ke, Jyh-Bin"

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A HEURISTIC ALGORITHM FOR THE OPTIMIZATION OF M/M/s QUEUE WITH MULTIPLE WORKING VACATIONS
(2012-02-01)
Wu, Chia-Huang
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Wang, Kuo-Hsiung
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Ke, Jau-Chuan
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Ke, Jyh-Bin
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工業工程與管理學系
This paper focuses on an M/M/s queue with multiple working vacations such that the server works with different service rates rather than no service during the vacation period. We show that this is a generalization of an M/M/1 queue with working vacations in the literature. Service times during vacation period, or during service period and vacation times are all exponentially distributed. We obtain the useful formula for the rate matrix R through matrix-geometric method. A cost function is formulated to determine the optimal number of servers subject to the stability conditions. We apply the direct search algorithm and Newton-Quasi algorithm to heuristically find an approximate solution to the constrained optimization problem. Numerical results are provided to illustrate the effectiveness of the computational algorithm.
Optimal management for a finite M/M/R queueing system with two arrival modes
(2007)
Wang, Kuo-Hsiung
;
Ke, Jyh-Bin
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Pearn, W. L.
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工業工程與管理學系
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Department of Industrial Engineering and Management
We consider an M/M/R queueing system with finite capacity N, where customers have two arrival modes under steady-state conditions. It is assumed that each arrival mode is serviced by one or more servers, and that the two arrival modes have equal probabilities of receiving service. Arrival times of the customers and service times of the severs follow an exponential distribution. A cost model is developed to determine the optimal number of servers and the optimal system capacity. The minimum expected cost, the optimal number of servers, the optimal system capacity, and various system characteristics are obtained for some designated system parameters' values. Sensitivity for the minimal cost is also investigated.