Business > QUESTIONS & ANSWERS > Review_Sheet_2_-_Managing_Variability-_Solutions. (All)

Review_Sheet_2_-_Managing_Variability-_Solutions.

Document Content and Description Below

Review Sheet 2: Managing Variability1 Suggested Answers 1. A Petroleum Refinery* An integrated petroleum company is considering expansion of its one unloading facility at its Australian refinery. ... Due to random variations in weather, loading delays, and other factors, ships arriving at the refinery to unload crude oil arrive according to the Poisson distribution (CVa=1) with an average arrival rate of 8 ships per week. Service time is exponential with an average service rate of 12 ships per week (CVS=1) Mean arrival rate of ships to facility: = 8 ships / week Mean service time per ship at facility (capacity of facility):  = service rate = 12 ships / week Mean utilization rate of facility:  = 8 ships per week/ 12 ships per week = 0.666 (66.6% busy) a) Current performance measures: i. What is the average number of ships waiting to gain access to the single unloading facility? Little’s Law tells us that Lq  Wq , so once we find Wq, we will have Lq. Because arrivals are Poisson, CVA2  1, and because service times are exponential, CVS2  1. Also note that  1/   0.0833 weeks.     67(weeks) (weeks) 0.1 1 1 1 2 (1 0.666) 0.666 0.0833 1 2 (1 ) 2 2        Wq CVA CVS    and thus, Lq   Wq  8ships/week  0.167 weeks 1.336 ships 1 Problems are rated for difficulty: * = Relatively easy, for first review of concepts; ** = Challenging, assumes good understanding of the concepts; *** = Advanced, assumes full understanding of the concepts and creativity in application. [Show More]

Last updated: 2 years ago

Preview 1 out of 6 pages

Buy Now

Instant download

We Accept: