Chapter 1 - Introduction to Simulation

Question 1

What is a simulation?

Answer 1

The imitation of the operation of a real-world pross or system over time

(uses mathematical models to simulate behaviour)

motivated by ‘what if’ questions about the real-world systems

Question 2

Why use simulations?

Answer 2

• to study complex system and its internal interactions
• to observe the effect of informational, organizational, and environmental changes on a system’s behaviours
• to improve the performance of a system
• to verify analytic solutions
• to help visualize a system

Question 3

When to not simulate?

Answer 3

• can solve problem with common sense
• can solve problem analytically
• if experiment is less expensive
• simulation is more expensive than potential savings from the simulation results
• no data is available for system

Question 4

Advantages of simulation

Answer 4

• can study system for new features or scenarios without disrupting the real system
• testing of new products
• feasibility studies
• ‘what if’ questions answered

Question 5

Disadvantages of simulation

Answer 5

• special training required for model building
• can be difficult to interpret
• can be time consuming and expensive

Question 6

Examples of application areas

Answer 6

• industrial manufacturing
• semiconductor fabrication
• business processing
• engineering and project management
• operations research
• military
• health care

Question 7

What is a system?

Answer 7

• A GROUP OF OBJECTS THAT ARE JOINED TOGETHER IN REGULAR INTERACTIONS OR INTERDEPENDENCE TOWARDS THE ACCOMPLISHMENT OF SOME PURPOSE

Question 8

Entity

Answer 8

object of interest

Question 9

attribute

Answer 9

property of entity (ex. type of customer/type of account)

Question 10

Activity

Answer 10

duration of time

Question 11

state

Answer 11

represented by state variables (state of the system)
- a collection of variables that relate the state of the system depending on the input (ex. # busy tellers or length of line)

Question 12

event

Answer 12

incident that changes the state of a system (ex. arrival of a new customer)

Question 13

delay

Answer 13

unwanted wait time

Question 14

discrete system

Answer 14

state variables take only discrete values

Question 15

continuous system

Answer 15

state variables change continuously over time

Question 16

What is a model?

Answer 16

a representation of a system for the purpose of studying that system

• a simplification of a system (may have/need different models of the same system to investigate different parts of the system)
• model should be sufficiently realistic to obtain valid conclusions about the actual system
• NO MODEL IS PERFECT

Question 17

static model

Answer 17

equation is regulated by algebraic equation (ex. V = IR)

Question 18

dynamic model

Answer 18

differential equations
- needs past inputs to calculate (initial conditions of model)

Question 19

Deterministic model

Answer 19

systems have a single output (no randomness)

Question 20

stochastic model

Answer 20

uses statistical distributions to predict certainty of results

Question 21

Steps in a simulation study

Answer 21

1. problem formulation
2. setting of objectives and overall project plan
3. model conceptualization
4. data collection
5. model translation
6. verify model
7. Experimental design
8. production runs and analysis
9. more runs
10. documentation and reporting
11. implementation

(this is an iterative process)