简介:DespiteextensiveresearchonR-trees,mostoftheproposedschemeshavenotbeenintegratedintoexistingDBMSowingtothelackofprotocolsofconcurrencycontrol.R-linktreeisanacceptabledatastructuretodealwiththisissue,butproblemslikephantomstillexist.Inthispaper,wefocusonaconflictdetectionschemebasedonR-linktreeforcompleteconcurrencycontrol.Anin-memoryoperationcontrollistisdesignedtosuspendconflictingoperations.Themainfeaturesofthisapproachare(1)itcanbeimplementedeasilyanddoesnotneedanyextrainformation;(2)Nodeadlocksareinvolvedinlockingscheme;(3)Non-conflictingoperationsarenotrestricted;and(4)PhantomproblemsinR-linktreeareavoidedthroughbeforehandpredication.Theexperimentresultsshowthatthisschemeiscorrectandgainsbettersystemperformance.
简介:Inthisnotesomerecurrencerelationsforthedimensionsofthesplinespacesonsocalled0-starsarepresented.
简介:TheS-RHTtechnologyisdevelopedbyFRIPPforresiduehydrotreatinginthefixedbedinordertoprocessthehighsulfurcrudeandincreasetheyieldoflightdistillates.Thetechnologycanbeusedfortreatingvariouskindsofatmosphericresidues(AR)orvacuumresidues(VR)withatotalmetalcontentlessthan150ppmundertheoperatingconditionsofatemperaturerangingfrom360-410℃,ahydrogenpartialpressureof14-15MPa,aLHSVof0.20-0.30h-1andahydrogentooilratioof700-1000.AcertainamountoflightproductscanbeobtainedandthehydrotreatedatmosphericresiduecanfullymeettheneedsforthefeedstocktoRFCCorablendingfeedstocktoFCC.BasedontheS-RHTtechnology,a2Mt/aresiduehydrotreatingunithasbeenconstructedandsuccessfullystartedupatMaomingPetrochemicalCompanybytheendof1999.
简介:Toavoidtheinaccurateestimationoftheactiveuser'snumberandthecorrespondingperformancedegradation,anovelPOR-basedUserIdentificationDetector(UID)isproposedfortheCodeDivisionMultipleAccess(CDMA)systems.ThenewdetectoradoptsthePowerofR(POR)techniqueandtheMultipleSignalClassification(MUSIC)method,whichdoesnotrequiretheestimationofactiveusers'number,andobtainslowerfalsealarmprobabilitythanthesubspace-basedUIDinthemultipathchannels.However,fromouranalysis,increasingtheordermdoesnotimprovetheperformance.Therefore,whenmisone,theperformanceofthenewdetectorismaximal.