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# Queue size discipline unlimited fifo d 22 queuing

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Unformatted text preview: lation Queue Size Discipline Unlimited FIFO D – 22 Queuing Models Model Name Example D Limited Limited population (finite population) Shop with only a dozen machines that might break Number of Channels Number of Phases Arrival Rate Pattern Service Time Pattern Single Single Poisson Exponential Population Queue Size Discipline Limited FIFO D – 23 Model A – Single-Channel 1. Arrivals are served on a FIFO basis and every arrival waits to be served regardless of the length of the queue 2. Arrivals are independent of preceding arrivals but the average number of arrivals does not change over time 3. Arrivals are described by a Poisson probability distribution and come from an infinite population D – 24 Model A – Single-Channel 4. Service times vary from one customer to the next and are independent of one another, but their average rate is known 5. Service times occur according to the negative exponential distribution 6. The service rate is faster than the arrival rate D – 25 Model A – Single-Channel λ = Mean number of arrivals per time Mean period period µ = Mean number of units served per time Mean period period Ls λ = Average number of units (customers) in Average the–system (waiting and being served) tµ λ he = Ws1 = Average time a unit spends in the Average µ–λ system (waiting time plus service time) system = D – 26 Model A – Single-Channel Lq = Average number of units waiting Average in the queue in λ2 = µ(µ – λ ) µ(µ Wq = Averag...
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## This document was uploaded on 02/19/2014.

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