Chapter 3

1. Chapter 3 Simulation Software

2. Outline • Introduction • Comparison of simulation packages with programming languages • Classification of simulation software • Desirable software features • Examples of application-oriented simulation packages Prof. Huei-Wen Ferng

3. Several Features for Discrete-Event Simulation Models • Generating random numbers • Generating random variates • Advancing simulated time • Determining the next event • Adding/deleting records • Collecting statistics and reporting results • Detecting error conditions Prof. Huei-Wen Ferng

4. Outline • Introduction • Comparison of simulation packages with programming languages • Classification of simulation software • Desirable software features • Examples of application-oriented simulation packages Prof. Huei-Wen Ferng

5. Advantages of Using a Package • Significant decreasing of time and cost • Natural framework • Models are easier to modify and maintain • Better error detection Prof. Huei-Wen Ferng

6. Advantages of General-Purpose Programming • Less execution time • Greater programming flexibility • Lower software cost Prof. Huei-Wen Ferng

7. Outline • Introduction • Comparison of simulation packages with programming languages • Classification of simulation software • Desirable software features • Examples of application-oriented simulation packages Prof. Huei-Wen Ferng

8. General-Purpose v.s. Application-Oriented Simulation Packages • General-purpose simulation is suitable for specific requirements • Application-oriented simulation package is designed to be used for a certain class of applications Prof. Huei-Wen Ferng

9. Review of Modeling Approaches • Event-scheduling • Process approach Prof. Huei-Wen Ferng

10. Prof. Huei-Wen Ferng

11. Prof. Huei-Wen Ferng

12. Common Modeling Elements • Simulation packages typically include • Entities: travel through some part of the simulated system, and then us usually destroyed. • Attributes: are pieces of information stored with the entity. • Resources: entity may require resources • Queues: if a requested resource is not available, then it joins a queue. Prof. Huei-Wen Ferng

13. Prof. Huei-Wen Ferng

14. Outline • Introduction • Comparison of simulation packages with programming languages • Classification of simulation software • Desirable software features • Examples of application-oriented simulation packages Prof. Huei-Wen Ferng

15. Desirable Software Features • General capabilities, including flexibility and ease of use • Hardware and software considerations • Animation • Statistical features • Customer support and documentation • Output reports and plots Prof. Huei-Wen Ferng

16. General Capabilities • Modeling flexibility • Ability to define and change attributes etc. • Ability to use mathematical expressions and functions • Ability to create new modeling constructs and to modify existing ones • Ease of use • Hierarchical modeling Prof. Huei-Wen Ferng

17. General Capabilities (Cont’d) • Good debugging aids • Follow a single entity through the model to see if it is processed correctly • See the state of model every time a particular event occurs • See the value of certain attributes or variables • Fast model execution speed • User-friendly model front ends Prof. Huei-Wen Ferng

18. General Capabilities (Cont’d) • To automatically simulate different scenarios • Be able to invoke external routines • To be easily initialized in a nonempty and idle state • The state of a simulation can be saved at the end of a run • Lower cost Prof. Huei-Wen Ferng

19. Hardware and Software Requirements • Types of computers • Windows-based PCs? • UNIX workstations? • Apple computers? • Etc. • The amount of RAM • Operation systems supported Prof. Huei-Wen Ferng

20. Animation and Dynamic Graphics • Some of use of animation • Easy communication with a manager or non-technical people • Debugging the simulation program • Showing that a simulation is not valid • Suggesting improved operational procedures • Training operational personnel • Promoting communication among the project team Prof. Huei-Wen Ferng

21. Animation and Dynamic Graphics (Cont’d) • Two fundamental types of animation • Concurrent and post-processed (playback) • Desire features for animation • Providing default animation • To create high-resolution icons • Library of standard icons • Smooth movement of icons • A control to speed up or slow down • Be possible to zoom in/out • Use vector-based graphics rather than pixel-based graphics • Be possible to import CAD drawings • To display dynamic graphics and statistics Prof. Huei-Wen Ferng

22. Statistical Capabilities • Having a good random-number generator • Independent replication of the simulation models • Each run uses separate sets of different random numbers • Each run uses the same initial conditions • Each run resets the statistical counters Prof. Huei-Wen Ferng

23. Statistical Capabilities (Cont’d) • A statistically sound method • Be able to determine a warm-up period based on making pilot runs • To specify what performance measures to collect • Allow to perform statistical experiment designs • Optimization? Prof. Huei-Wen Ferng

24. Customer Support and Documentation • Public training • Customized training • Good documentation • Free demo disk • Money-back free trial of the software • Newsletters Prof. Huei-Wen Ferng

25. Output Reports and Graphics • Be possible to customize reports • Reports at intermediate nodes are available • Database to store results • To export individual model output observations Prof. Huei-Wen Ferng

26. Outline • Introduction • Comparison of simulation packages with programming languages • Classification of simulation software • Desirable software features • Examples of application-oriented simulation packages Prof. Huei-Wen Ferng

27. Package Examples • Manufacturing • AutoMod, Arena etc. • Communications networks • OPNET, NS2, Q+, Bones, etc. Prof. Huei-Wen Ferng