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.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
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