1. Lab Module 05 Entity Routing
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

2. Objectives and Outline
Lab Objectives
Continue learning basic Simio modeling
Learn two different methods to route entities in Simio
Link Selection Weights
Dynamic routing using node lists
Lab Outline
Video 1 – Using Selection Weights for probabilistic routing
Video 2 – Using Selection Weights for conditional routing
Video 3 – Using Node Lists for dynamic routing
Video 4 – Assignments
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

3. Video 1 – Using Selection Weights for Routing
Adjust
Arrive
Inspect
Depart
80% Pass
20% Fail
TV final adjustment and inspection process
TVs arrive at the rate of 20/hour (exponential interarrival times)
Adjustment takes approximately 2 minutes (uniformly distributed between 1.75 and 2.25)
Inspection takes approximately 1.75 minutes (exponentially distributed)
20% of inspected TVs are found to need re-adjustment
Interested in Time In System, Number In System, Utilizations of Adjust and Inspect
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

4. Re-entrant Flow and Effective Arrival Ratep l
1-p
𝜆 ′ =𝜆+𝑝 𝜆 ′
𝜆 ′ = 𝜆 1−𝑝
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

5. Selection Weights 𝑝 𝑖 = 𝑤 𝑖 𝑗=1 𝑛 𝑤 𝑗wn
Link selection probability for link i :
𝑝 𝑖 = 𝑤 𝑖 𝑗=1 𝑛 𝑤 𝑗
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

6. Video 2 – Conditional Routing Using Selection Weights
Maximum of 3 adjustments for a given TV
Adjust
Arrive
Inspect
Depart
80% Pass
20% Fail
TV final adjustment and inspection process
TVs arrive at the rate of 20/hour (exponential interarrival times)
Adjustment takes approximately 2 minutes (uniformly distributed between 1.75 and 2.25)
Inspection takes approximately 1.75 minutes (exponentially distributed)
20% of inspected TVs are found to need re-adjustment
Interested in Time In System, Number In System, Utilizations of Adjust and Inspect
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

7. Video 3 – Dynamic Routing Using Node Lists
Server1
Arrive
Depart
Server2
Server3
Approx. 10 minutes
Approx. 5 minutes
Approx. 1 minute
Arrival rate: 60/hour
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

8. Video 4 - Assignment Using the TV Adjust/Inspect model:
“Fix” the issue where the TV’s are adjusted the 4th (and inspected) time even though we know that they will be rejected after inspection. Hint: Start by inserting a Basic Node in the path from the Inspect server back to the Adjust server.
Create a reference property for the maximum number of adjustments allowed and develop an experiment that compares the configurations with values 1, 2, 3, 4, 5, 100.
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved

9. Video 4 - Assignment
Using the dynamic routing model (from the third video):
Develop an experiment with 25 replications using a run length of 500 hours with a 250 hour warm-up and responses for the three server utilizations, the entity time in system (TIS) and entity number in system (NIS)
Using the base model, compare the 5 performance metrics using the following routing alternatives:
Probabilistic routing using the selection weights 6/78, 12/78, and 60/78
Preferred order with capacity 5 buffers at each server
Using AssociatedStationOverload with no buffers (capacity 0 buffers)
Using AssociatedStationOverload with capacity 5 buffers
Using the shortest queue length with infinite capacity buffers
Copyright © Jeffrey S. Smith and Simio LLC | All Rights Reserved