外文翻译高级数据库应用.docx

外文翻译高级数据库应用.docx

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外文翻译高级数据库应用

毕业设计（论文）

外文翻译

题目高级数据库应用

专业信息与计算科学

班级

学生

指导教师

AdvancedDatabaseApplications

The1990shaveseensignificantchangesinthecomputerindustry.Indatabasesystems,wehaveseenthewidespreadacceptanceofRDBMSsfortraditionalbusinessapplications,suchasorderprocessing,inventorycontrol,banking,andairlinereservations.However,existingRDBMSshaveproveninadequateforapplicationswhoseneedsarequitedifferentfromthoseoftraditionalbusinessdatabaseapplications.Theseapplicationsinclude:

■computer-aideddesign（CAD）;

■computer-aidedmanufacturing（CAM）;

■computer-aidedsoftwareengineering（CASE）;

■officeinformationsystems（OIS）andmultimediasystems;

■digitalpublishing;

■eographicinformationsystems（GIS）;

■interactiveanddynamicWebsites.

Computer-aideddesign（CAD）

ACADdatabasestoresdatarelatingtomechanicalandelectricaldesigncovering,forexample,buildings,aircraft,andintegratedcircuitchips.Designsofthistypehavesomecommoncharacteristics:

■Designdataischaracterizedbyalargenumberoftypes,eachwithasmallnumberofinstances.Conventionaldatabasesaretypicallytheopposite.Forexample,theDreamHomedatabaseconsistsofonlyadozenorsorelations,althoughrelationssuchasPropertyForRent,Client,andViewingmaycontainthousandsoftuples.

■Designsmaybeverylarge,perhapsconsistingofmillionsofparts,oftenwithmanyinterdependentsubsystemdesigns.

■Thedesignisnotstaticbutevolvesthroughtime.Whenadesignchangeoccurs,itsimplicationsmustbepropagatedthroughalldesignrepresentations.Thedynamicnatureofdesignmaymeanthatsomeactionscannotbeforeseenatthebeginning.

■Updatesarefat-reachingbecauseoftopologicalorfunctionalrelationships,tolerances,andsoon.Onechangeislikelytoaffectalargenumberofdesignobjects.

■Often,manydesignalternativesarebeingconsideredforeachcomponent,andthecorrectversionforeachpartmustbemaintained.Thisinvolvessomeformofversioncontrolandconfigurationmanagement.

■Theremaybehundredsofstaffinvolvedwiththedesign,andtheymayworkinparallelonmultipleversionsofalargedesign.Evenso,theend-productmustbeconsistentandcoordinated.Thisissometimesreferredtoascooperativeengineering.

Computer-aidedmanufacturing（CAM）

ACAMdatabasestoressimilardatatoaCADsystem,inadditiontoadditiontodatarelatingtodiscreteproduction（suchascarsonanassemblyline）andcontinuousproduction（suchaschemicalsynthesis）.Forexample,inchemicalmanufacturingtherewillbeapplicationsthatmonitorinformationaboutthestateofthesystem,suchasreactorBesseltemperatures,flowrates,andyields.Therewillalsobeapplicationsthatcontrolvariousphysicalprocesses,suchasopeningvalves,applyingmoreheattoreactorvessels,andincreasingtheflowofcoolingsystems.Theseapplicationsareoftenorganizedinahierarchy,withatop-levelapplicationmonitoringtheentirefactoryandlower=levelapplicationsmonitoringindividualmanufacturingprocesses.Theseapplicationsmustrespondinrealtimeandbecapableofadjustingprocessestomaintainoptimumperformancewithintighttolerances.Theapplicationsuseacombinationofstandardalgorithmsandcustomrulestorespondtodifferentconditions.Operatorsmaymodifytheserulesoccasionallytooptimizeperformancebasedoncomplexhistoricaldatathatthesystemhastomaintain.Inthisexample,thesystemhastomaintainlargevolumesofdatathatishierarchicalinnatureandmaintaincomplexrelationshipsbetweenthedata.Itmustalsobeabletorapidlynavigatethedatatoreviewandrespondtochanges.

Computer-aidedsoftwareengineering（CASE）

ACASEdatabasestoresdatarelatingtostagesofthesoftwaredevelopmentlifecycle:

planning,requirementscollectionandanalysis,design,implementation,testing,maintenance,anddocumentation.AswithCAD,designsmaybeextremelylarge,andcooperativeengineeringisthenorm.Forexample,softwareconfigurationmanagementtoolsallowconcurrentsharingofprojectdesign,code,anddocumentation.Theyalsotrackthedependenciesbetweenthesecomponentsandassistwithchangemanagement.Projectmanagementtoolsfacilitatethecoordinationofvariousprojectmanagementactivities,suchastheschedulingofpotentiallyhighlycomplexinterdependenttasks,costestimation,andprogressmonitoring.

Networkmanagementsystems

Networkmanagementsystemscoordinatethedeliveryofcommunicationservicesacrossacomputernetwork.Thesesystemsperformsuchtasksasnetworkpathmanagement,problemmanagement,andnetworkplanning.Aswiththechemicalmanufacturingexamplewediscussedearlier,thesesystemsalsohandlecomplexdataandrequirereal-timeperformanceandcontinuousoperation.Forexamples,atelephonecallmightinvolveachainofnetworkswitchingdevicesthatrouteamessagefromsendertoreceiver,suchas:

Node

Link

Node

Link

Node

Link

Node

WhereeachNoderepresentsaportonanetworkdeviceandeachLinkrepresentsasliceofbandwidthreservedforthatconnection.However,anodemayparticipateinseveraldifferentconnectionsandanydatabasethatiscreatedhastomanageacomplexgraphofrelationships.Torouteconnections,diagnoseproblems,andbalanceloadings,thenetworkmanagementsystemshavetobecapableofmovingthroughthiscomplexgraphinrealtime.

Officeinformationsystems（OIS）andmultimediasystems

AnOISdatabasestoresdatarelatingtothecomputercontrolofinformationinabusiness,includingelectronicmail,documents,invoices,andsoon.Toprovidebettersupportforthisarea,weneedtohandleawiderrangeofdatatypesotherthannames,addresses,dates,andmoney.Modernsystemsnowhandlefree-formtext,photographs,diagrams,andaudioandvideosequences.Forexample,amultimediadocumentmayhandletext,photographs,spreadsheets,andvoicecommentary.Thedocumentsmayhaveaspecificstructureimposedonthem,perhapsdescribedusingamark-uplanguagesuchasSGML（StandardizedGeneralizedMarkupLanguage）,HTML（HyperTextMarkupLanguage）,orXML（eXtendedMarkupLanguage）,aswediscussinChapter29.

Documentsmaybesharedamongmanyusersusingsystemssuchaselectronicmailandbulletin-boardsbasedonInternettechnology.Again,suchapplicationsneedtostoredatathathasamuchricherstructurethantuplesconsistingofnumbersandtextstrings.Thereisalsoanincreasingneedtocapturehandwrittennotesusingelectronicdevices.AlthoughmanynotescanbetranscribedintoASCⅡtextusinghandwritinganalysistechniques,mostsuchdatacannot.Inadditiontowords,handwrittendatacanincludesketches,diagramsandsoon.

IntheDreamHomecasestudy,wemayfindthefollowingrequirementsforhandlingmultimedia.

■ImagedataAclientmayqueryanimagedatabaseofpropertiesforrent.Somequeriesmaysimplyuseatextualdescriptiontoidentifyimagesofdesirableproperties.Inothercasesitmaybeusefulfortheclienttoqueryusinggraphicalimagesoffeaturesthatmaybefoundindesirableproperties（suchasbaywindows,internalcornicing,orroofgardens）.

■VideodataAclientmayqueryavideodatabaseofpropertiesforrent.Somequeriesmaysimplyuseatextualdescriptiontoidentifythevideoimagesofdesirableproperties.Inothercasesitmaybeusefulfortheclienttoqueryusingvideofeaturesofthedesiredproperties（suchasviewsoftheseaorsurroundinghills）.

■AudiodataAclientmayqueryanaudiodatabasethatdescribesthefeaturesofpropertiesforrent.Somequeriesmaysimplyuseatextualdescriptiontoidentifythedesiredproperty.Inothercasesitmaybeusefulfortheclienttouseaudiofeaturesofthedesiredproperties（suchasthenoiselevelfromnearbytraffic）.

■HandwrittendataAmemberofstaffmaycreatenoteswhilecarryingoutinspectionsofpropertiesforrent.Atalaterdata,heorshemaywishtoquerysuchdatatofindallnotesmadeaboutaflatinNovarDrivewithdryrot.

Digitalpublishing

Thepublishingindustryislikelytoundergoprofoundchangesinbusinesspracticesoverthenextdecade.Itisbecomingpossibletostorebooks,journals,papers,andarticleselectronicallyanddeliverthemoverhigh-speednetworkstoconsumers.Aswithofficeinformationsystems,digitalpublishingisbeingextendedtohandlemultimediadocumentsconsistingoftext,audio,image,andvideodataandanimation.Insomecases,theamountofinformationavailabletobeputonlineisenormous,intheorderofpetabytes（1015bytes）,whichwouldmakethemthelargestdatabasesthataDBMAhaseverhadtomanage.

Geographicinformationsystems（GIS）

AGISdatabasestoresvarioustypesofspatialandtemporalinformation,suchasthatusedinlandmanagementandunderwaterexploration.Muchofthedatainthesesystemsisderivedfromsurveyandsatellitephotographs,andtendstobeverylarge.Searchesmayinvolveidentifyingfeaturesbased,forexample,onshape,color,ortexture,usingadvancedpattern-recognitiontechniques.

Forexample,EOS（EarthObservingSystem）isacollectionofsatelliteslaunchedbyNASAinthe1990stogatherinformationthatwillsupportsci8entistsconcernedwithlong-termtrendsregardingtheearth’satmosphere,oceans,andland.Itisanticipatedthatthesesatelliteswillreturnoverone-thirdofapetabyteofinformationperyear.ThisdatawillbeintegratedwithotherdatasourcesandwillbestoredinEOSDIS（EOSDataandInformationSystem）.EOSDISwillsupplytheinformationneedsofbothscientistsandnon-scientists.Forexample,schoolchildrenwillbeabletoaccessEOSDIStoseeasimulationofworldweatherpatterns.Theimmensesize