cs144 - 01 - structure of system

8/8/2019 CS144 - 01 - Structure of System

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Simulation & Modeling

Kardi Teknomo, PhD

Some of the materials in this slide are my summary from Principle of System by Jay W. Forrester,Productivity, 1971


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Kardi Teknomo, PhD

Overview System

System Boundary

ass ca on o ys ems:

Open System

Positive feedback system

Ne ative feedback s stem


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Objective By the end of this lesson you should be


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Kardi Teknomo, PhD

1. System Definition: System is a grouping of

a common purpose

A system is a part of some potential reality

where we are concerned with s ace-timeeffects and causal relationship among parts ofthe system

A system may include people as well asphysical parts


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Kardi Teknomo, PhD

System as a black box We define a system to be a closed world

integral parts of the system from items

outside


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Example of System: Family Family is a system for living and raising

Picture source: or.ucr.edu


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Example of System: AutomobileAutomobile is a system of components

transportation

Picture Source:


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Example of System: WarehouseA warehouse and loading platform is a

Picture Source:http://www.rrii.com/images/Arlington_Warehouse_Pic.gif


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Kardi Teknomo, PhD

Example of System: management Management is a system of people for

activity of business

Picture source: http://www.ingres.com/images/about/group-pic-management.jpg


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Kardi Teknomo, PhD

Example of System: Web Web is an ecosystem

ys ems w n e we eBay

Blogosphere

Digg Flickr

MySpace

Picture source:

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/WorldWideWebAroundWikipedia.png/800px-WorldWideWebAroundWikipedia.png


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Discussion & Exercise

Can you find other system?

a are e componen s o e sys em What is the purpose of the system?


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2. Structure

Definition: A structure is effective

observation in any field of knowledge

Without an organizing structure,

observations, practices and conflictingincidents


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Interacting Components

Any specified behavior of a system must

interacting components.

Those components lie within a boundarythat defines and encloses the system


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Example of Structure: Physics

The law of Physics is a structure to

nature.

This structure of physical knowledge isthe foundation of todays technology

Picture source:https://reader009.{domain}/reader009/html5/0524/5b06b009e8b72/5b06b011c7d72.jpg


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Example of Structure: System Management

Management system is a structure to

psychological, industrial and economic


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Causal Thinking

Causal thinking is the key to organizing

Instead of cause, affect or influence

can be used to describe the relatedcomponents in the system


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Understand Cause & Effect

Some are logical (e.g. physics)

Money happiness

Some are not e. . sociolo economics Use of seatbelts reduced highway

fatalities

Shortened daylight hours increasedsuicide rates


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3. System Boundary

Where is the boundary, that

components, within which the dynamic


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Self-contained system

Self-Contained System: nothing flow in

Most s stem are not self-contained They function in an environmentthat


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Difficulty in defining Boundary

1. Difficult to decide at what level the

Subopmitization: decision that optimize

optimal for the system as a whole

.overlapping parts with other system

. cu o e ne e n age w eenvironment


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Closed System

In concept, a feedback system is a closed.

Its dynamic behavior arises within its

internal structure

behavior mode being investigated must


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Building Blocks

Within the system boundary the basic.

Interconnection of feedback loops form a

system


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4. Classification of System

System can be classified into

pen sys em

Feedback (closed) system


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4a. Open System

An open system is one characterized by

the outputs are isolated from and have

It is not aware of (observe and react to ) itsown performance

Its past action oes not contro uture action


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Kardi Teknomo, PhD

Example of Open system: Watch

A watch, taken by itself, is an open

own inccuracy and adjust itself

Picture source: https://reader009.{domain}/reader009/html5/0524/5b06b009e8b


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Example of Open System: Car

A car is an open system which by itself is

past nor does it have a goal of where to

Picture source: http://www.global-rental.com


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Discussion: open system

Can you find other open system?

xp a n w y o you n s an opensystem


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4b. Feedback System

It is also called Closed System

A feedback system has a closed loop structure

system back to control future action

Feedback system control action is influenced by theresults of its own previous action or past behavior

Its past action control present and future action


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Feedback Loop

Well conceived systems contain feedack loop.

Feedback involves monitoring the actual

behavior to standards

Information about deviation from standard is

system so that effective action can be taken

K di T k PhD


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Kardi Teknomo, PhD

Category of Feedback System

There are two classes of feedback

Positive feedback: growth

ega ve ee ac : goa see ng

Kardi Teknomo PhD


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4b1. Positive Feedback System

Positive feedbackgenerates growth

that generate still greater action

It is in the positive feedback form ofsystem structure that one finds the forcesof growth

Kardi Teknomo PhD


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Example (+) Feedback System

Bacteria multiply to produce more bacteria

are generated

Picture source:http://www.scharfphoto.com/fine_art_prints/archives/199812-053-Soil-Bacteria.

In this positive feedback system the generation

accumulated from past growth of bacteria

Kardi Teknomo PhD


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4b2. Negative Feedback System

Negative feedback system seeks a goal

to achieve the goal

It is in the negative feedback, or goalseeking, structure of systems that onefinds the causes offluctuation and

instability

Kardi Teknomo, PhD


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Kardi Teknomo, PhD

Example (-) Feedback System: AC

Air conditioning system of a house is controlledb a thermostat which re onds to the heat

previously produced by the AC

Picture source:http://www.rd.com/images/tfhimport/2001/May01_Air_Conditioner_Clean/20010501_Air_Conditioner_Clean_page002img001_size2.jpg

Kardi Teknomo, PhD


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AC (cont)

Because the heat already produced by

generation of heat, the AC system

the goal of proper temperature

Kardi Teknomo, PhD


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,

Example (-) Feedback System

A watch and its owner form a negative

compared with the correct time as a goal

eliminate error

Picture source:

https://reader009.{domain}/reader009/html5/0524/5b06b009e8b72/5b06b02038

Kardi Teknomo, PhD


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View Point

Whether a system should be classified as an

intrinsic to the particular assembly of parts butdepend on the observers view point in definingthe purpose of the system

You can always broaden the scope and purposeof the system to change from open to feedback

system and from feedback to open system

Kardi Teknomo, PhD


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Review Classification of Systems

System:

pen sys em:

Past action does not control future action

r y :

Past action controls future action

Positive feedback loop

Ne ative feedback loo

Depend on observers viewpoint

Kardi Teknomo, PhD


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Summary

You have learned in this lesson about

ys em n ng

System definition

ystem structure

System boundary

Kardi Teknomo, PhD


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Discussion & Exercise: System Structure

Please select any system that interesting

Can you draw the system structure?

Specify the parts or components of

system as variables of the system Then draw arrow to connect the influence

of one art to the other art

Kardi Teknomo, PhD


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Discussion: Boundary

Define from your system:

ow e var a es n uence o er var a e

Is it a closed or open system?

an you in some ee ac oop

Can you draw the system boundary (to makea c ose sys em

Kardi Teknomo, PhD


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Discussion Points

Define from your system:

Is it open or feedback system?

How the variable influence other variable

loops

Keep your discussion for next week

Kardi Teknomo, PhD


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Tips

When there is a double arrow in the influence,

that have not been specified

Select variables that can be measured

uantitativel b an means

direct effect (increase or decrease). Indirecteffect indicates lack of variables in between

Kardi Teknomo, PhD


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Tips

Change level of details of some variables to

cs144 - 01 - structure of system

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