DCT Analysis

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DCT Analysis
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Concepts
UML-like class model of essential classes and
actions.
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Conceptual model
Simplest model connected queues. More advanced
models differ between 3 classes of trucks and
various actions of crane.
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Essence 2 connected queues. (only 8 exceptions
out of 500)
Most important parameters rk (keeper occupation
rate) rc (crane occupation rate)
Assume M/D/1 queues (exp arrival, const
processing) if rk rc, then crane queue empty. If
rk lt rc, then average queue length keeper
C/(1-rk) average queue length cranekeeper
C/(1-rc) (approximately for some constant C)
If e.g. rk 0.9 and rc 0.91, then keeper queue
10C and crane queue C. Greatest capacity problem
with crane, though! c.f. Arena model DCT.doe in
"examples" directory.
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Problem large queues keeper queue
largest. Causes keeper occupation rate too
high, also crane capacity? Crane queue
waiting time 35 of keeper waiting time, so crane
capacity is an issue!
Solutions increase keeper productivity. Investiga
te crane occupation rate. Increase crane
productivity also.
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Short-term temporary solution increase working
hours. Cost extra payment to workers, which is
manageable ("business is booming"). Benefits
less dissatisfaction of customers.
Longer term solution for keeper problem use IT!
Crane solutions (in any combination) - faster
crane - double queue - improve container storage
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Assignments

• 4-5 assignments throughout the course
• Bonus for exam max. 2 points
• Bonuses awarded for overall qualityand nice
  parts (e.g. concepts, problem analysis and
  suggestions).
• This assignmentscore 8 full bonus
  (.4)OK(7) small bonus (.2)

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Impression

• Much enthousiasm and hard work.
• Some reports were very good (talent or
  experience). Need course?
• Others need not despair.Hopefully course will
  help you.