Basicfeatures
Thebasicfeaturesofthesystemstructure:stability,hierarchy,openness,andrelativity.
Thesystemstructureisalsousedtodescribethedivisionanddefinitionoftheinterfacesbetweenalllevelsofmachinesinthecomputersystem,aswellastheallocationoffunctionsaboveandbelowtheinterfacesatalllevels.Eachlevelhasitsownsystemstructure.
Composition
Concept
Acollectionofinterconnectedsystemelementsorganizedaccordingtoacertainrulefromthepurposeofthesystem.
Elements
Inthemostbasicsense,thesystemiscomposedofinterrelatedelements.Elementsrefertothebasiccomponentsoftheinternalstructurethatdonotneedtobedecomposedandinvestigatedforthepurposeoftheresearchsystem.Forexample,anairlineownsaircraft,staff,andvariousequipment.Thesearetheelementsintheairlinesystem.
Large-scalesystemsandsubsystems
Somesystems,especiallylarge-scalesystems,canbedecomposedintoseveralsubsystemstofacilitateresearch.Subsystemsplayanelementalroleintheactivitiesoflarge-scalesystems,butwhenitisnecessarytoexaminethestructureofsub-systems,theycanbebrokendownintosmallersub-systems.Forexample,acountryisalarge-scalesystem,whichconsistsofpoliticalsubsystems,Itiscomposedofeconomicsubsystem,culturaleducationsubsystem,nationalsecuritysubsystem,etc.Andthesesubsystemsarecomposedofseveralsmallersubsystems,suchastheeconomicsubsystemiscomposedofindustry,agriculture,commerce,transportationandothersubsystems.Element-subsystem-systemisacertainwayofexpressingthehierarchicalstructureofthesystem,andthisdecompositionisnotunique.
Relevanceofelementsandsubsystems
Theinterrelationship(function,influence,relationship,etc.)betweenelementsorsubsystemsisanotheraspectofthesystemstructure.Twodifferentsystemscanbecomposedofsetsofelementsthatareidenticaltoeachother,buttheelementshavedifferentassociations.Forexample,aninductancecoilandacapacitorcanbeassociatedindifferentways(suchasseries,parallel)toformaseriesresonancesystemoraparallelresonancesystem.Therefore,twosystemswithdifferentstructuresmayhavedifferentelementsinthetwosystems,ortheymayhavethesameelementsbutdifferentassociationsbetweentheelements.
Systemarchitecturediagram
Thesystemstructurecanberepresentedbythesystemstructurediagram(seefigure).Inthefigure,thebigcirclesrepresentsthesystem,andthesmallcircleinsidesiss1,s2,...,snrepresentsanelementorsubsystem,andthelinebetweenthesmallcirclesrijrepresentstheassociationbetweensiandsj.