intro modeling1

7/27/2019 Intro Modeling1

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INTRODUCTION TO MODELING

AND SIMULATION


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Lesson 1: Introduction to Modeling and simulation

1.0 Modeling Concepts1.1 What is a Model?

1.2 Why models are developed?

1.3 Types of Model1.4 When to use Model?

1.5 Characteristics of a good model

1.6 Principles of Modeling


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INTRODUCTORY ACTIVITY

Enumerate instances/situations/scenarios where youuse/apply models and why?

Write a short essay (maybe 1-3 printed pages) answering

the question

Why do we use a model? simulation to studysomething?


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1. Three (3) main types of models

Process

Physical

Mathematical


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2. Things which can be modeled?

System

Environment

Bahaviour


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3. Applications of simulation

Aid to thought

Communication

Training

Prediction

Experimentation

Entertainment


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answers

4. Advantages of Simulation


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Quick Review

1. Things which can be modeled2. Types of models

3. Applications of simulation

4. Types/Categories of Simulation5. Advantages of simulation

6. Categories of simulation


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1.1 What is a Model?

The wordmodel

is derived from Latin word

modellus and itsmeaning is mould or pattern (physical model).

A representation of an object, a system, or an idea in some form other

than that of the entity itself.

A model is a set of assumptions/approximations about how the system

works A modelis a simplified representation of a system at some particular

point in time or space intended to promote understanding of the real

system.

The representation of an object in some form other than the form of

the object itself, usually for the purpose of study or experimentation


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1.3 Classification of Models

1. Physical: an actual representation

2. Schematic: a pictorial representation

3. Descriptive: a verbal description

4. Mathematical: components are described mathematically,in the form of equations

5. Heuristics: descriptive model based on rules; algorithmic; -

computer based (monte-carlo simulation)

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Physical

(Prototypes)

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Analytical

(Mathematical)

2

1

q

q q

W W

L W

13

Single Stage Queuing Model

1W

L W

1

)( nNPn


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Computer

(Monte Carlo Simulation)

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Descriptive

(Performance analysis)

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Simulation

vs.

Real World


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Schematic

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Examples of Models in Vehicle Design

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1.4 When to use Model

To fly a simulator is safer and cheaperthan the real airplane. For precisely this reason, models are used in industry,

commerce

and military: it is very costly, dangerous and often impossible

tomake experiments with real systems.

Provided that models are adequate descriptions of reality(they are

valid), experimenting with them can save money, sufferingand even time.

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1.4 CHARACTERISTICS OF A GOOD MODEL

Close approximation to the real system

Simple to understand

Goal directed

Easy to control

Complete on important issues

Adaptive and easy to update

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1.5 PRINCIPLES OF MODELING

1. Do not build a complicated model when a simple one will suffice.

2. Beware of modeling the problem to fit the technique.3. The deduction phase of modeling must be conducted rigorously

(conclusions one draws from results).

4. Models should be validated prior to implementation.

5. A model should never be taken too literally.

Modelinginvolves observing a system, noting the various components, then

developing a representation of the system that will allow for further study of orexperimentation on the system.


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1.5 PRINCIPLES OF MODELING cont.

6. A model should never be pressed to do, nor criticized for failing todo, that for

which it was never intended.

7. Beware of overselling a model.

8. Some of the primary benefits of modeling are associated with the

process of

developing the model.

9. A model cannot be any better than the information going into it.

10. Models cannot replace decision makers.


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Quick Review

1. Applications of simulation2. Types/Categories of Simulation

3. Advantages of simulation


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MODELING AND SIMULATION QUOTES

ONE OF THE GREAT VALUES OF SIMULATION IS ITS ABILITY

TO EFFECT A TIME AND SPACE COMPRESSION ON THE

SYSTEM, ESSENTIALLY ALLOWING ONE TO PERCEIVE, IN A

MATTER OF MINUTES, INTERACTIONS THAT WOULD NORMALLY

UNFOLD OVER VERY

LENTGHY TIME PERIODSGene Bellinger


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Summary: MODELING AND SIMULATION

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