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简介：Cloudcomputingisatechnologythatprovidesuserswithalargestoragespaceandanenormouscomputingpower.However,theoutsourceddataareoftensensitiveandconfidential,andhencemustbeencryptedbeforebeingoutsourced.Consequently,classicalsearchapproacheshavebecomeobsoleteandnewapproachesthatarecompatiblewithencrypteddatahavebecomeanecessity.Forprivacyreasons,mostoftheseapproachesarebasedonthevectormodelwhichisatimeconsumingprocesssincetheentireindexmustbeloadedandexploitedduringthesearchprocessgiventhatthequeryvectormustbecomparedwitheachdocumentvector.Tosolvethisproblem,weproposeanewmethodforconstructingasecureinvertedindexusingtwokeytechniques,homomorphicencryptionandthedummydocumentstechnique.However,1)homomorphicencryptiongeneratesverylargeciphertextswhicharethousandsoftimeslargerthantheircorrespondingplaintexts,and2)thedummydocumentstechniquethatenhancestheindexsecurityproduceslotsoffalsepositivesinthesearchresults.Theproposedapproachexploitstheadvantagesofthesetwotechniquesbyproposingtwomethodscalledthecompressedtableofencryptedscoresandthedoublescoreformula.Moreover,weexploitasecondsecureinvertedindexinordertomanagetheusers'accessrightstothedata.Finally,inordertovalidateourapproach,weperformedanexperimentalstudyusingadatacollectionofonemilliondocuments.Theexperimentsshowthatourapproachismanytimesfasterthananyotherapproachbasedonthevectormodel.

简介：

简介：Thebuildinginformationmodel/modeling(BIM)technologyiscurrentlyappliedinabroadrangeofapplicationsandresearchforfacilitymanagement,whiletheBIM-basedmobileFMisdifficultowingtovariousfactorsandenvironments.Forexample,themobileapplicationsusuallyrequirefrequentcross-equipmentcompatibility.ThispaperproposesareasonableBIM-basedFMcross-platformframeworkanddevelopsamobileapplicationonthebasisofanexistingBIM-basedFMsystem.ThedevelopedmobileapplicationisappliedinacasestudyofametrostationprojectinGuangzhoutoverifyitseffectivenessinFMpractice.IthelpsmaintenancestaffinviewingBIMs,accessingrelatedinformation,andupdatingmaintenancerecordsinauniqueplatform.ThetestresultsdemonstratethattheproposedBIM-basedcross-platformframeworkmeettheFMapplicationrequirementsandsupportstheextensionofFMfunctions.