8.5 Exercises
Exercise 8.1 Consider the STEM Career Fair Mixer of Example 7.7. Change the model so that the implementation uses
the DistancesModel class to represent the travel distances. Use the moveTo() function to model the movement of the students within the STEM Career Fair. Compare your results to the implementation in Chapter 7.
Exercise 8.2 Consider the implementation of the tandem queue with constrained movement in Section 8.2.3. Change the model so that the implementation uses the following movable resource allocation rules.
MovableResourceAllocateInOrderListedRuleFurthestMovableResourceAllocationRuleLeastUtilizedMovableResourceAllocationRuleRandomMovableResourceAllocationRule(with stream 4)
Compare your results with those of Section 8.2.3. Which rule do you recommend and why?
Exercise 8.3 Consider the implementation of the Test and Repair Shop of Section 8.3. Change the model so that the implementation uses the following movable resource allocation rules.
MovableResourceAllocateInOrderListedRuleFurthestMovableResourceAllocationRuleLeastUtilizedMovableResourceAllocationRuleRandomMovableResourceAllocationRule(with stream 4)
Compare your results to the results of Section 8.3. Which rule do you recommend and why?
Exercise 8.4 Reconsider Exercise 7.2. Assume that there is a pool of 3 workers that perform the transport between the stations. Assume that the transport time is triangularly distributed with parameters (2, 4, 6) all in minutes. Make an assessment for the company for the appropriate number of workers to have in the transport worker pool.
Exercise 8.5 Consider the implementation of the Test and Repair Shop of Section 8.3. Re-analyze this situation and recommend an appropriate number of transport workers.
Exercise 8.6 Reconsider Exercise 8.4. The distances between the four stations (in feet) are given in the following table. After the parts finish the processing at the last station of their sequence they are transported to an exit station, where they begin their shipping process.
| Station | A | B | C | D | Exit | |
| A | – | 50 | 60 | 80 | 90 | |
| B | 55 | – | 25 | 55 | 75 | |
| C | 60 | 20 | – | 70 | 30 | |
| D | 80 | 60 | 65 | – | 35 | |
| Exit | 100 | 80 | 35 | 40 | – |
There are 2 fork trucks in the system. The velocity of the fork trucks varies within the facility due to various random congestion effects. Assume that the fork truck’s velocity between the stations is triangularly distributed with parameters (3, 4, 5) miles per hour. Simulate the system for 30000 minutes and discuss the potential bottlenecks in the system.
Exercise 8.6 Reconsider the Test and Repair example from Section 8.3 In this problem, the workers have a home base that they return to whenever there are no more waiting requests rather than idling at their last drop off point. The home base is located at the center of the shop. The distances from each station to the home base are given in as follows.
| Station | Diagnostics | Test 1 | Test 2 | Test 3 | Repair | Home base | |
| Diagnostics | – | 40 | 70 | 90 | 100 | 20 | |
| Test 1 | 43 | – | 10 | 60 | 80 | 20 | |
| Test 2 | 70 | 15 | – | 65 | 20 | 15 | |
| Test 3 | 90 | 80 | 60 | – | 25 | 15 | |
| Repair | 110 | 85 | 25 | 30 | – | 25 | |
| Home base | 20 | 20 | 15 | 15 | 25 | – |
Rerun the model using the same run parameters as the chapter example and report the average number of requests waiting for transport. Give an assessment of the risk associated with meeting the contract specifications based on this new design.
Exercise 8.7 (This problem is based on an example on page 223 of (Pegden, Shannon, and Sadowski 1995). Used with permission) Reconsider Exercise 7.11. Assume that all parts are transferred by using two fork trucks that travel at an average speed of 150 feet per minute. The distances (in feet) between the stations are provided in the table below.
| Enter | Workstation | Paint | New Paint | Pack | Exit | |
|---|---|---|---|---|---|---|
| Enter | – | 325 | 445 | 445 | 565 | 815 |
| Workstation | – | 120 | 130 | 240 | 490 | |
| Paint | – | 250 | 120 | 370 | ||
| New Paint | – | 130 | 380 | |||
| Pack | – | 250 | ||||
| Exit | – |
The distances are symmetric. Both the drop-off and pickup points at a station are at the same physical location. Once the truck reaches the pickup/drop-off station, it requires a load/unload time of two minutes.
Analyze this system to determine any potential bottleneck operations. Report on the average flow times of the parts as a whole and individually. Also obtain statistics representing the average number of parts waiting for allocation of a transporter and the number of busy transporters. Run the model for 600,000 minutes with a 50,000 minute warm up period.