1ENMA 6010: System Modeling, Simulation, and Analysis - Overview© 2009 – Mark PolczynskiAll rights reserved

BA (Before AutoCad)

People have been building amazingly complex systems for a long time.

In the old days, for example, ship designs often consisted of exact scale models.

Basically, the designer said:Build a ship exactly like this,(except bigger).

Today, these models adorn theshelves of maritime museumsand hobby shops.

But originally, these modelswere essential to systemdesign and construction.

2ENMA 6010: System Modeling, Simulation, and Analysis - Overview

3ENMA 6010: System Modeling, Simulation, and Analysis - Overview

Modern System Design

Today, being much advanced over ourancestors, we generally say:

“Build a system something like this…”

And, what we get, of course, is somethinglike the system we want.

Now, technological advances enable us to conceive of ever-larger systems of ever-increasing complexity and interdependency.

The result is that often the systems we are designing and buildingdeviate further and further from what it is that we originally imagined.

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The complexity of the systems we are buildingis approaching that of human behavior.

For these systems, we have incomplete a-priori knowledge of:

• Nature - design/function:How a particular system would behave under all possibleexpected and unexpected conditions.

• Nurture - environment/history:How previous and current external factors cause temporary

and permanent changes in the behavior of a system.

• Growth - changes in nature and nurture:How the behavior of the system will be required to change over time in order to remain viable.

Complex systems can behave as irrationally as people!

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Like human beings, system behaviors can be:

- Difficult to understand and predict,

- Often appear illogical, inconsistent, even self-destructive.

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Problem: As systems become larger, more complex, and more interdependent, the task of conceptualizing and specifying function and design increases dramatically.

Solution: Go back to the old ways!

The basic premise of this course is that the best design specification for large complex systems is a descriptive model of the system.

This course is all about:

•Modeling, simulating, and analyzing systems…

•In ways that completely and accurately capture the behavior of the desired system implementation.

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What is this course NOT about?

•This course is not about AutoCad, Simulink, or rapid prototyping.

•These topics are well-covered by the Mechanical Engineering Department.

•Rather, we cover a wide range of general tools from many different disciplines which can be used to model, simulate, and analyze large complex systems.

•The intent is to provide the current or perspective engineering manager with an overview of a wide range of tools in the system modeling toolbox.

•This will help the student:• Understand the strengths and limitations of available tools,• Select appropriate tools,• Evaluate the results of using the tools.

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What this course is NOT about – Part 2

•This course is not about training expert practitioners in the use of the tools covered.

•In fact, it is assumed that as engineering managers, students may never themselves actually apply the tools.

•However, as managers, students can be expected to manage teams and/or projects that utilize these tools.

•To that end, this course provides the student with the chance to apply the tools to real-world problems,

•Thereby providing the understanding and technical credibility to effectively manage the use of such tools.

ENMA 6010: System Modeling, Simulation, and Analysis - Overview 9

Goals of System Modeling:

1.To focus on important system features while downplaying less important features,

2.To verify that we understand the user’s environment,

3.To discuss changes and corrections to the user’s requirements at low cost and with minimal risk,

4.To verify that we have documented our understanding in a way that would allow others to construct/maintain the system.

ENMA 6010: System Modeling, Simulation, and Analysis - Overview 10

Characteristics of Good Models:

1.Graphical, with support for detailed text descriptions: Picture is worth a thousand words picture links to a thousand words.

2.Top-down partitionable: Globe Continents Countries etc…

3.Minimally redundant: Make changes in just one place in the model.

4.Transparent: Requires no expertise in model building to understand the model.

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Modeling tools we will be using in this course:

1.Context Diagram: Scope and boundaries of model.

2.Entity Relationship Diagram: Interactions between system elements.

3.Entity Flow Diagram: Movement of patients and materials.

4.State Transition Diagrams: Transitions between system wait states.

5.Process Flow Diagrams: Decisions controlling system behavior.

6.Causal Loop Diagram: System cause and effect relationships.

7.IBIS Analysis: Description of “fuzzy” decisions.

8.Monte Carlo Simulation: Entity flow and resource utilization.

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State transition diagram

State transition diagram

Entity relationship

diagram

Entity relationship

diagram

Process flow

diagram

Process flow

diagram

Entity flow diagram

Entity flow diagram

Part 1of this Course

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Danger:

Because we are pulling modeling techniques from different fields,we will occasionally run into terminology conflicts, e.g.:

Data flow diagram Entity flow diagram