1. CS 450 Modelling and Simulation Dr. X

2. Topics Time Discrete and Continuous Simulation Simulation Design Process

3. Simulation Accuracy Can it ever be perfect? When is it good enough?

4. Coin Toss Simulation

5. Time Time is nature’s way of keeping everything from happening all at once. -Anonymous

6. Time in Simulations Core of everything that happens Events are anchored by when they occur Independent variable that exists in ALL simulations

7. Event Timeline

8. Time in Simulations AnimationAnimation Timeline

9. Continuous Simulations Examples: – Physical processes – Chemical Processes How to: – Use mathematical functions – Convert analog to digital Sample rate Visualization

10. Discrete Simulations Distinct, identifiable events Events occur at specific times Time in between does not interest us Example: queuing models, tetris

11. When Discrete Becomes Continuous

12. Hybrid Simulations

13. How to simulate time Sequencing Set Data Collection Events Continuous State Evaluation Animation timeline

14. States and Events

15. Simulation Design: what is important? Can we include all the details of a real system? How do we decide what is important?

16. Needs Analysis Performance gap in training simulation – Scale – Risk – Complexity – Product Design

17. Needs Analysis When is simulation not appropriate? – Simple technology would work as well or better – Not enough data – Real life activity is less expensive, not dangerous – Incomplete understanding of the system – Uncertain objectives

18. Step-Wise Refinement 1.Original System 2.Observable Elements 3.Conceptual Model 4.Operational Model 5.Computer Implementation

19. Step-Wise Refinement

21. The OR Approach 1. Problem formulation 2. Construction of the model 3. Model validation 4. Using the model, evaluate various available alternatives (solution) 5. Implementation and maintenance of the solution

23. Fill the table Original System System Activities Observable Elements Obtainable Data Simulation Events Simulation Input Data Collectible Data Traffic Intersection Computer Network NY City under the attack of Vampires Ebola virus in Africa

24. References The Guide to Computer Simulations and Games, By Katrin Becker and J.R.Parker, Wiley (Chapter 5) Computer Simulation Techniques: The Definitive Introduction, by Harry Perros, http://www4.ncsu.edu/~hp/simulation.pdf http://www4.ncsu.edu/~hp/simulation.pdf CS 45024