SOLUTIONS MANUAL for Stochastic Modeling: Analysis and ...
SOLUTIONS MANUAL for Stochastic Modeling: Analysis and ...
SOLUTIONS MANUAL for Stochastic Modeling: Analysis and ...
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122 CHAPTER 9. TOPICS IN SIMULATION OF STOCHASTIC PROCESSES<br />
so a complete cycle is approximately s/6 + 8 hours.<br />
The number of orders <strong>for</strong> the summer is<br />
720<br />
s/6+8<br />
The expected number of lost bags is<br />
( ) 720<br />
(48)<br />
s/6+8<br />
And the average stock level is<br />
1/2(s/6)s<br />
s/6+8<br />
11. To obtain a rough-cut model we will (a) ignore the interaction of loading bays <strong>and</strong><br />
<strong>for</strong>klifts, <strong>and</strong> (b) treat all service times as exponentially distributed (later we refine<br />
(b)).<br />
• Adding a <strong>for</strong>k lift.<br />
We first treat the number of bays as unlimited.<br />
λ = 6.5 trucks/hour<br />
1/µ = 15 minutes = 1/4 hour<br />
BasedonanM/M/3model<br />
w q =0.05hours=3minutes<br />
l q = 0.3 trucks<br />
ρ = λ = 6.5 ≈ 0.54 utilization<br />
3µ 12<br />
Now treating the bays as servers we use an M/M/4 model with<br />
λ =6.5<br />
1/µ = 15 + 15 = 30 minutes = 1/2 hour<br />
w q = 0.41 hour = 25 minutes<br />
l q = 2.7 trucks in the lot<br />
Approximate total time: 0.41 + 0.05 + 1/2 = 0.96 hour ≈ 58 minutes.<br />
• Adding a bay<br />
Again start by treating the bays as unlimited, <strong>and</strong> the <strong>for</strong>klifts as an M/M/2 with<br />
λ =6.5<br />
1/µ = 1/4