Transcript Queues - Junior University :: Homepage

Queues
Examples of Queue Problems
Post Office
(Each counter with all services v Different counters
for different services)
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T-Mobile Customer Service
(How many operators to employ and when ?)

Airport
(What is the chance that the aircraft will have to
wait before landing ?)
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Basic Language of Queues
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Arrivals (Probability distribution)
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Service mechanism
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Queue discipline
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Service time variability
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Service discipline
Variability of arrivals
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Number of arrivals changes in each time
period.
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Assume 2 arrivals cannot occur
simultaneously.
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Assume infinite queue potential
Service mechanism
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Usually controlled
Single channel or multi-channel
(eg. Toll booths, ASDA etc)

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Multiple channels may be in series
Queue discipline
Jockeying
 Balking
 FIFO
 LIFO
 Random
 Queue jumping
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Service Time variability
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Measured by a frequency distribution
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Might be affected by numbers in the
queue
Service discipline
Fixed batches
(eg. Tour of mine shaft)
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Fish shop
(eg. Battered cod is just cookin’)
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Which is best ?
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(a) 3 channels in parallel each operating at
mean service rate = 10 per hour;
OR
(b) 1 channel with a mean service rate of
30 per hour ?
The answer is …
(b) By 2.6 minutes per customer !
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OK .. Now look at the Excel worksheet.