18oktsystem concepts

8/12/2019 18OktSystem Concepts

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SystemConcepts

Jurusan

Teknik

Industri

ITS


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Asystemisanorganize assem yo components. Organize meanst at

there existspecialrelationshipsbetweenthecomponents.

Thes stemdoessomethin i.e.itexhibitsbehaviours thatareuni ueto

the system.

Eachcomponentcontributestowardsthebehaviour ofthesystemandits

.

independent effecton

the

system.

Groupsofcomponentswithinthesystemmaybythemselveshave

properties.

Thesystemhasanoutside anenvironment whichprovidesinputs

.

Thesystemhasbeenidentifiedbysomeonetobeofspecialinterestfora

given purpose.


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Theseparationbetweenthesystemandits

environmentmeans

that

there

is

aboundar .

Infact,boundaryselectionisthemostcritical

. Outthere&insideusview


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ecomp ex yo rea emay esuc a we avenooronlyincompleteknowledge oftheinnerworkingsofa

system,even

if

we

are

able

to

identify

the

physical

components.

Oftenthemajorreasonforthislackofknowledgeisthat.

Inother

cases,

the

relationships

between components

are

onlypartiallyunderstood

Inothersituationsthetransformationprocessisknownexactly.However, ratherthanrepresentitinfulldetail,itma be ade uate to view the inner workin as a black box

andsimplyexpressthevariousactivitiesofthetransformation processbyasinglefunctionalrelationship


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Discretesystems(adiscretesystemchangesits

stateat

discrete

points

in

time)

Thenumberoftelephonelinesorthenumberof

operatorsbusy

Inapredator/prey

system,

the

state

is

described

by

thenumberofpredatorsand numberofpreyaliveat

anypointintime

Inthe

loom repair

system,

two

state

variables

of

primeinterestarethenumberofmachines operating

andthenumberofmachinesbrokendown


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ContinuousSystem(thestateofthesystem

chan escontinuousl )

Manyindustrialprocesses,particularlyinchemical

,

continuoussystems.

maintainthebodytemperaturewithinanarrow

.


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Deterministic&StochasticSystem

Ifthe

behaviour of

as stem

is

redictable

in

ever

detailthesystemisdeterministic.Forexample,

thesolars stem animated neon advertisin si ns

thatgo

through

aregular

pattern,

asequence

of

trafficli htsalon aonewa street

Ifthebehaviourofasystemis notcompletely

inputs,thesystemsarecalledstochasticsystems.


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TheSteadyStateofaProbabilistic

System toc ast c systems nt e ongrunten toapproac a

state

of

equilibrium, also

called

a

steady

state.

This

systemstartsoutfrom.

equilibrium.Small

or

large random

disturbances,

e.g.

a

suddenrandomsurgeofemergencycalls,oraseverestorminanecologicalsystem,maydisruptsystem

behaviour and

push

it

away

from these

long

run

averages. u neac case, esys emw gra ua yapproachthe sameoranewstateofequilibriumagain.


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ee ac sacommon ea ureo mos sys ems,

both

human

activity

systems

and natural

systems.

.

Feedbackcanactpositivelyornegatively.

thefuture

state

of

the

system

and

some

reference

state,suchasan equilibriumstateoradesiredtargets a e. no erwor s, esys ems a e en s odeviatemoreandmorefromitsreferencestate.

,

discrepancybetweenthefuturestateandthereferencestate


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reecon onsarenee e oexerc secon ro oversys embehaviour:

Atar et

ob ective

or

oal

for

the

s stem

to

reach.

For

a

deterministicsystemthis maybeaparticularstateofthesystem.Forstochasticsystemsitmaybea desirablesteady

.

Asystem

capable

of

reaching

the

target

or

goal.

The

difficultyisthatforstochasticsystemstheremaybenowayo guaran ee ng a sgoa severreac e .

Somemeansofinfluencingsystembehaviour.Thesearethe

control in uts decisions decision rules or initial states .Howthesecontrolinputsaffectsystem behaviour isan

importantaspectofstudyingsystems.


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OpenLoopControl

FeedForwardControl


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Inputs imposedonthesystembasedonlyon

the

redictionof how

the

s stem

behaviour

respondstothem.Noaccountistakenofhow

inputs.


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Information aboutthesystembehaviour,

ossibl

in res onseto

revious

control

inputs,isfedbacktothecontrollerfor

.

adjustthe

control

signals.

Therearetwomechanism:

Feedback

control

Selfregulation


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Reacts tochangesinsomecriticalstatevariables

or outputs.Rather

than

react

to

events

after

they

havehappened,afeedforwardcontrol

mechanism redictshowchan esinin uts

(uncontrollableor

controllable)

are

likely to

affect

s stem behaviour and then sends control si nals

thatwillmaintainsystem behaviour ascloselyas

,

counteracting the effectsofinputdisturbances


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TheProblemSituation

JurusanTeknikIndustriITS


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Thecontextwithinwhichtheproblemoccurs.Itisthesum oraggregateofallaspectsthatcanormayaffectorshapethe

problemorissueof concern.


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Thedecisionmaker

Theassociateddecisioncriterion

The

performance measure

action

The contextinwhichtheproblemoccurs


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no ec ve s een owar sw c e or s rec e , anaim,goalorendofaction anambulanceservicewants

tofind

the

best

location in

asmall

city,

where

best

is

interpretedasreachinganyemergencyasquicklyaspossible

judgment ordecision

is

based.

Both

principle

and

standardimplyarule.Soacriterionis theruleusedfor

achieved tominimizethesumofall timestoreach

every

road

location

in

town,

to

minimize

the

sum

of

the

square

mes ,

om n m ze

emax mum

me

e ween

theambulanceservice andanylocationsinthecity.


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Definethesixproblemelementsfor

Emer enc

callcentre

roblem

Vehicleroutingproblem


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Definethestakeholdersfor

Emer enc

callcentre

roblem

Vehicleroutingproblem


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Goa s:

Acquiringasufficiently

complete

and

detailed

un erstan ngo t epro ems tuat on orasuccessfulsystemintervention

onthe

outcome

Mindmaps

Cognitive maps


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enyout n a outsomet ng ap enomenon,anissue,oraproblem ahostofthoughtsareevokedin

,

,

,

andaims,dataandfacts,andthepossibleactionsandreactionsb ourselforother eo leorentitiesinvolved

andtheir

consequences, both

planned

and

unplanned,

desirableandundesirable,thatresultfromsuchactions,an t ewi ercontextorenvironmento ita .Amin

mapisallthis(orajudiciously chosensubset)putdown

,

,


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Thethingsarearrangedinameaningfulwayby

showin

as ectsclosel

related in

rou s,

b

linesthatconnectthingswhicharerelated,and

betweenitems.

No

formal

conventions

are

used.


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at ert ans owt evar ousaspects nwor sors ortsentences,P.Checkland [1993/99]suggestsdrawinga

everything!)theobserverknowsaboutthesituationstudied. Notethattermrich icturedoesnot inthefirst

place,mean

adrawing.

It

is simply

amore

colourful term

forasituationsummary.Itscartoonlikerepresentationisca e aric picture iagram.However,t isisrat er

clumsyandlong.Soifitis clearfromthecontext,wewill

.


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sys emmo e sarepresen a ono a essen apartsofasystem

:

Iconic

Mathematical

Simple

Easytomanipulate&communicatewith

Ada tive


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CONSTRAINTS DECISION

FEEDBACKS

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