学科分类
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19 个结果
  • 简介:AlatticeBoltzmannnumericalmodelingmethodwasdevelopedtopredictskinconcentrationaftertopicalapplicationofadrugontheskin.ThemethodisbasedonD2Q9latticespacesassociatedwiththeBhatnagar-Gross-Krook(BGK)collisiontermtosolvetheconvection-diffusionequation(CDE).Asimulationwascarriedoutindifferentrangesofthevalueofbound,whichisrelatedtoskincapillaryclearanceandthevolumeofdiffusionduringapercutaneousabsorptionprocess.Whenatypicaldrugisusedontheskin,thevalueofcorrespondstotheamountofdrugabsorbedbythebloodandtheabsorptionofthedrugaddedtotheskin.Theeffectofwasstudiedforwhentheregionofskincontactisalinesegmentontheskinsurface.

  • 标签: Lattice BOLTZMANN method Bhatnagar-Gross-Krook (BGK) Single
  • 简介:Acombustionmodelofalarge-scalesupercriticalcirculatingfluidizedbed(CFB)boilerwasdevelopedforcomprehensivecomputational-fluid-dynamicsanalysis.Themodelincorporatesgas-solidhydrodynamics,coalcombustion,heattransferonheatexchangesurfacesinthefurnace,andheattransferbetweenfumaceandworkingmediumintheheattransfertubes.Insimulatingthedenseanddilutephasesinthefumace,thegas-solidhydrodynamicsisbasedontheEuler-Eulermodelandenergy-minimizationmultiscaledragmodel.Coalcombustionentailsevaporation,devolatilization,charcombustion,gashomogeneousreaction,andpollutantemission.Thecoefficientofheattransferbetweengas-solidandthewaterwallisestimatedusingtheclusterrenewalmodel,andforradiation,thediscreteordinatemodelisused.Moreover,thermohydraulicprocessesinthemembranewallarealsoineludedintheheattransferprocess.Themodelwassuccessfullyappliedinsimulationsofa350-MWsupercriticalCFBboiler.Detaileddistributionsofsolidsconcentration,oxygen,heatflux,andworkingmediumtemperatureintheboilerfurnacearepresented.

  • 标签: COMPREHENSIVE combustion model COMPUTATIONAL fluid dynamic
  • 简介:Intheanalysisanddesignofimportantstructureswithrelativelylonglifespans,thereisaneedtogeneratestrongmotiondataforpossiblelargeevents.Thesourceofanearthquakeischaracterizedbythespatialdistributionofsliponthefaultplane.Forfutureevents,thisisunknown.Inthispaper,astochasticearthquakesourcemodelisdevelopedtoaddressthisissue.Here,1Dand2DstochasticmodelsforslipdistributiondevelopedbyLavalléeetal.(2006)areused.Therandomfieldassociatedwiththeslipdistributionisheavy-tailedstabledistributionwhichcanbeusedforlargeevents.Using236pastrupturemodels,thespectralscalingparameterandthefourstableorLevy’sparametersagainstempiricalrelationshipforknownquantitieslikemagnitudeorfaultlengtharedeveloped.Themodelisvalidatedwithdatafrom411stationsof1999Chi-Chiearthquake.Thesimulatedresponsespectrumshowedgoodagreementtoactualdata.Furthertheproposedmodelisusedtogenerategroundmotionforthe1993KillariEarthquakewherestrongmotiondataisnotavailable.Thesimulatedmeanpeakgroundvelocitywasinturnrelatedtotheintensity(MSK)andcomparedagainstvaluesintheliterature.

  • 标签: STOCHASTIC SLIP distribution GROUND MOTION Levy’s
  • 简介:Aratmodelofchronictympanicmembraneperforationwasdevelopedtobeusedinthesearchofnewmaterialsforthesealingoftheseperforations.AlongitudinalstudywascarriedoutinratssubjectedtoincisionalmyringotomyfollowedbytheapplicationofmitomycinCaloneorwithdexamethasone.Ratswerecheckedatdays3,7,10,14andweeklythereafteruntilperforationclosure,forupto6months.Theadditionofdexamethasoneisakeycomponentinordertoobtainachronicopening.Myringotomiestreatedwithsalinehadameanhealingtimeof8.5days.At8weeks,between62.5%and77.7%oftympanicmembranestreatedwithmitomycinCanddexamethasoneremainedperforatedandat6monthsthisnumberfellto21.4%.Thistechniqueisabletomaintainmosttympanicmembraneperforationspatentforatleast8weeks.Thisratmodelisadequateforitsuseinpreclinicalortranslationalresearch.

  • 标签: ANIMAL model CHRONIC tympanic MEMBRANE PERFORATION
  • 简介:MarmaraSea,locatedbetweenBlackSeaandAegeanSea,isanimportantseaforoceanengineeringactivities.Inthisstudy,wavepowerpotentialofMarmaraSeawasinvestigatedusingthethirdgenerationspectralwind-wavemodelMIKE21SWwithunstructuredmesh.WinddatawasobtainedfromECMWFERA-Interimre-analyseswinddatasetat10mwithaspatialresolutionof0.1?fortheperiodof1994to2014.ThenumericalmodelwascalibratedwithmeasuredwavedatafromabuoystationlocatedinMarmaraSea.Meshoptimizationwasalsoperformedtoobtainthemostsuitablemeshstructureforthestudyarea.ThisstudyisthefirstthatdealtwiththedeterminationofwaveenergypotentialofMarmaraSea.Thenumericalmodelresultsarepresentedintermsofmonthly,seasonalandannualaverageofwavepowerflux(kWm-1).Themaximumwavepowerfluxis1.13kWm-1andoccursinNovember.Theoverallannualmeanwavepowerfluxduring1994–2014isfoundtobe0.27kWm-1intheoffshoreregions.

  • 标签: MARMARA Sea MIKE 21 SW WAVE
  • 简介:ThegoalofthisstudyistoanalyzethestatisticsofthebackscattersignalfrombovinecancellousboneusingaNakagamimodelandtoevaluatethefeasibilityofNakagami-modelparametersforcancellousbonecharacterization.Ultrasonicbackscattermeasurementswereperformedon24bovinecancellousbonespecimensinvitroandthebackscattersignalswerecompensatedforthefrequency-dependentattenuationpriortotheenvelopedetection.ThestatisticsofthebackscatterenvelopeweremodeledusingtheNakagamidistribution.Ourresultsrevealthatthebackscatterenvelopemainlyfollowedpre-Rayleighdistributions,andthedeviationsofthebackscatterenvelopefromRayleighdistributiondecreasedwithincreasingbonedensity.TheNakagamishapeparameter(i.e.,m)wassignificantlycorrelatedwithbonedensities(R=0.78–0.81,p<0.001)andtrabecularmicrostructures(|R|=0.46–0.78,p<0.05).Thescaleparameter(i.e.,?)andsignal-to-noiseratio(SNR)alsoyieldedsignificantcorrelationswithbonedensityandstructuralfeatures.Multiplelinearregressionsshowedthatbonevolumefraction(BV/TV)wasthemainpredictoroftheNakagamiparameters,andmicrostructureproducedsignificantlyindependentcontributiontothepredictionofNakagamidistributionparameters,explaininganadditional10.2%ofthevarianceatmost.TheinvitrostudyshowedthatstatisticalparametersderivedwithNakagamimodelmightbeusefulforcancellousbonecharacterization,andstatisticalanalysishaspotentialforultrasonicbackscatterboneevaluation.

  • 标签: ULTRASONIC backscatter CANCELLOUS BONE STATISTICAL analysis
  • 简介:Anumericalmodelofthesteelcatenaryriser(SCR)isbuiltbasedontheslenderrodmodel.Theslenderrodmodel,whichdescribesthebehavioroftheslenderriserintermsofthecenterlineposition,cansolvethegeometricalnonlinearityeffectively.Inamarineenvironment,theSCRisunderthecombinedinternalflowandexternalloads,suchaswaveandcurrent.Ageneralanalysisconsidersonlytheinertialforceandthedragforcecausedbythewaveandcurrent.However,theinternalflowhasaneffectontheSCR;itisessentialtoexplorethedynamicresponseoftheSCRwiththeinternalflow.TheSCRalsosufferstheliftforceandthefluctuatingdragforcebecauseofthecurrent.Finiteelementmethodisutilizedtosolvethemotionequations.Theeffectsoftheinternalflow,waveandcurrentonthedynamicresponseoftheSCRareconsidered.TheresultsindicatethattheincreaseoftheinternalflowdensityleadstothedecreaseofthedisplacementoftheSCR,whiletheinternalflowvelocityhaslittleeffectontheSCR.ThedisplacementoftheSCRincreaseswiththeincreaseofthewaveheightandperiod.AndtheincreasingwaveperiodresultsinanincreaseinthevibrationperiodoftheSCR.ThecurrentvelocitychangesthedisplacementsoftheSCRinx-andz-directions.ThevibrationfrequencyoftheSCRiny-directionincreaseswiththeincreaseofthecurrentvelocity.

  • 标签: steel CATENARY RISER slender ROD model
  • 简介:Somestudieshavesuggestedthatearlysurgicaltreatmentcaneffectivelyimprovetheprognosisofcervicalspinalcordinjurywithoutradiologicalabnormality,butnoresearchhasfocusedonthedevelopmentofaprognosticmodelofcervicalspinalcordinjurywithoutradiologicalabnormality.Thisretrospectiveanalysisincluded43patientswithcervicalspinalcordinjurywithoutradiologicalabnormality.Sevenpotentialfactorswereassessed:age,sex,externalforcestrengthcausingdamage,durationofdisease,degreeofcervicalspinalstenosis,JapaneseOrthopaedicAssociationscore,andphysiologicalcervicalcurvature.Amodelwasestablishedusingmultiplebinarylogisticregressionanalysis.Themodelwasevaluatedbyconcordantprofilingandtheareaunderthereceiveroperatingcharacteristiccurve.Bootstrappingwasusedforinternalvalidation.Theprognosticmodelwasasfollows:logit(P)=-25.4545+21.2576VALUE+1.2160SCORE-3.4224TIME,whereVALUEreferstothePavlovratioindicatingtheextentofcervicalspinalstenosis,SCOREreferstotheJapaneseOrthopaedicAssociationscore(0–17)aftertheoperation,andTIMEreferstothediseaseduration(frominjurytooperation).Theareaunderthereceiveroperatingcharacteristiccurveforallpatientswas0.8941(95%confidenceinterval,0.7930–0.9952).Threefactorsassessedinthepredictivemodelwereassociatedwithpatientoutcomes:agreatextentofcervicalstenosis,apoorpreoperativeneurologicalstatus,andalongdiseaseduration.Thesethreefactorscouldworsenpatientoutcomes.Moreover,thediseaseprognosiswasconsideredgoodwhenlogit(P)≥-2.5105.Overall,themodeldisplayedacertainclinicalvalue.ThisstudywasapprovedbytheBiomedicalEthicsCommitteeoftheSecondAffiliatedHospitalofXi’anJiaotongUniversity,China(approvalnumber:2018063)onMay8,2018.

  • 标签: nerve REGENERATION SURGICAL prognostic model CERVICAL
  • 简介:Thefishbonemodelisasimplifiednumericalmodelformoment-resistingframesthatiscapableofmodellingtheeffectsofcolumn-beamstrengthandstiffnessratios.Theapplicabilityofthefishbonemodelinsimulatingtheseismicresponsesofreinforcedconcretemoment-resistingframesofdifferentsetsofcolumn-beamstrengthandstiffnessratiosareevaluatedthroughnonlinearstatic,dynamicandincrementaldynamicanalysisonsixprototypebuildingsof4-,8-and12-stories.Theresultsshowthatthefishbonemodelispracticallyaccurateenoughforreinforcedconcreteframes,althoughtheassumptionofequaljointrotationdoesnotholdinallcases.Inadditiontothegroundmotioncharacteristicsandthenumberofstoriesinthestructures,theaccuracyofthemodelalsovarieswiththecolumn-beamstiffnessandstrengthratios.Themodelperformsbetterforstrongcolumn-weakbeamframes,inwhichthelateraldriftpatternsarebettercontrolledbythecontinuousstiffnessprovidedbythestrongcolumns.Whentheinelasticdeformationislarge,theaccuracyofthemodelmaybesubjectedtolargerecord-to-recordvariability.Thisisespeciallythecaseforframesofweakcolumns.

  • 标签: FISHBONE MODEL reinforced concrete frame strong
  • 简介:Withthegrowingpopularityofcloud-baseddatacenternetworks(DCNs),taskresourceallocationhasbecomemoreandmoreimportanttotheefficientuseofresourceinDCNs.Thispaperconsidersprovisioningthemaximumadmissibleload(MAL)ofvirtualmachines(VMs)inphysicalmachines(PMs)withunderlyingtree-structuredDCNsusingthehosemodelforcommunication.Thelimitationofstaticloaddistributionisthatitassignstaskstonodesinaonce-and-for-allmanner,andthusrequiresaprioriknowledgeofprogrambehavior.Toavoidloadredistributionduringruntimewhentheloadgrows,weintroducemaximumelasticityscheduling,whichhasthemaximumgrowthpotentialsubjecttothenodeandlinkcapacities.Thispaperaimstofindtheschedulewiththemaximumelasticityacrossnodesandlinks.Wefirstproposeadistributedlinearsolutionbasedonmessagepassing,andwediscussseveralpropertiesandextensionsofthemodel.Basedontheassumptionsandconclusions,weextendittothemultiplepathscasewithafattreeDCN,anddiscusstheoptimalsolutionforcomputingtheMALwithbothcomputationandcommunicationconstraints.Afterthat,wepresenttheprovisionschemewiththemaximumelasticityfortheVMs,whichcomeswithprovableoptimalityguaranteeforafixedflowschedulingstrategyinafattreeDCN.Weconducttheevaluationsonourtestbedandpresentvarioussimulationresultsbycomparingtheproposedmaximumelasticschedulingschemeswithothermethods.Extensivesimulationsvalidatetheeffectivenessoftheproposedpolicies,andtheresultsareshownfromdifferentperspectivestoprovidesolutionsbasedonourresearch.

  • 标签: data center network (DCN) CLOUD DISTRIBUTED
  • 简介:Background:Preventinganteriorcruciateligament(ACL)injuriesisimportanttoavoidlong-termadversehealthconsequences.Identifyingbarrierstoimplementationofthesepreventionprogramsiscrucialtoreducingtheincidenceoftheseinjuries.OurpurposewastoidentifybarriersofimplementationforACLinjurypreventionprogramsandsuggestmechanismsforreducingthebarriersthroughapplicationofaSocioEcologicalModel(SEM).Methods:StudiesinvestigatingACLpreventionprogrameffectivenessweresearchedinMedlineviaPubMedandtheCochraneLibrary,andasubsequentreviewofthereferencesoftheidentifiedarticles,yielded15articlestotal.Inclusioncriteriaencompassedprospectivecontrolledtrials,publishedinEnglish,withACLinjuriesastheprimaryoutcome.Studieswereindependentlyappraisedby2reviewersformethodologicalqualityusingthePEDroscale.Barrierstoimplementationwereidentifiedwhenreportedinatleast2separatestudies.ASEMwasusedtosuggestwaystoreducetheidentifiedbarriers.Results:Fivebarrierswereidentified:motivation,timerequirements,skillrequirementsforprogramfacilitators,compliance,andcost.TheSEMsuggestedwaystominimizethebarriersatalllevelsofthemodelfromtheindividualthroughpolicylevels.Conclusion:IdentificationofbarrierstoprogramimplementationandsuggestinghowtoreducethemthroughtheSEMisacriticalfirststeptowardenablingACLpreventionprogramstobemoreeffectiveandultimatelyreducingtheincidenceoftheseinjuries.

  • 标签: Anterior CRUCIATE LIGAMENT INJURY PREVENTION Barriers
  • 简介:Inthisstudy,wesimulatedtyphoonwavesintheshallowwatersaroundtheZhoushanIslandsusingtheWaveWatch-III(WW3)modelversion5.16,thelatestversionreleasedbytheNationalOceanicandAtmosphericAdministration.Specifically,weusedin-situmeasurementstoevaluatetheperformanceofsevenpackagesofinput/dissipationsourcetermsintheWW3model.WeforcedtheWW3modelbywindfieldsderivedfromacombinationoftheparametricHollandmodelandhigh-resolutionEuropeanCenterforMedium-RangeWeatherForecasts(ECMWF)winddataina0.125°grid,hereincalledH-Ewinds.WetrainedtheH-EwindsbyfittingashapeparameterBtobuoy-measuredobservations,whichresultedinasmallestrootmeansquareerror(RMSE)of3ms?1forB,whentreatedasaconstant0.4.Then,weappliedtheseveninput/dissipationtermsofWW3,labelledST1,ST2,ST2+STAB2,ST3,ST3+STAB3,ST4,andST6,tosimulatethesignificantwaveheight(SWH)upto5mduringtyphoonsFungwongandChan-homaroundtheZhoushanIslands.WethencomparedtheSWHsofthesimulatedwaveswiththosemeasuredbythein-situbuoys.TheresultsindicatethatthesimulationusingST2performsbestwithanRMSEof0.79mfortyphoonFung-wongandanRMSEof1.12mfortyphoonChan-hom.Interestingly,wefoundthesimulatedSWHresultstoberelativelyhigherthanthoseoftheobservationsintheareabetweenHangzhouBayandtheZhoushanIslands.Thisbehaviorisworthyoffurtherinvestigationinthefuture.

  • 标签: WAVES TYPHOON WAVEWATCH-III Zhoushan ISLANDS
  • 简介:Thelargedesignfreedomofvariable-stiffness(VS)compositematerialpresupposesitspotentialforwideengineeringapplication.PreviousresearchindicatesthatthedesignofVScylindricalstructureshelpstoincreasethebucklingloadascomparedtoquasi-isotropic(QI)cylindricalstructures.Thispaperfocusesontheanti-bucklingperformanceofVScylindricalstructuresundercombinedloadsandtheefficientoptimizationdesignmethod.Twokindsofconditions,bendingmomentandinternalpressure,andbendingmomentandtorqueareconsidered.Influencesofthegeometricaldefects,ovality,onthecylinder'sperformancesarealsoinvestigated.Toincreasethecomputationalefficiency,anadaptiveKrigingmeta-modelisproposedtoapproximatethestructuralresponseofthecylinders.InthisimprovedKrigingmodel,amixedupdatingruleisusedinconstructingthemeta-model.Ageneticalgorithm(GA)isimplementedintheoptimizationdesign.TheoptimalresultsshowthatthebucklingloadofVScylindersinallcasesisgreatlyincreasedascomparedwithaQIcylinder.

  • 标签: Variable-stiffness composite Optimal anti-buckling DESIGN Combined
  • 简介:ScaleeffectofISWsloadsonFloatingProductionStorageandOffloading(FPSO)isstudiedinthispaper.TheapplicationconditionsofKdV,eKdVandMCCISWstheoriesareusedinthenumericalmethod.ThedepthaveragedvelocitiesinducedbyISWsareusedforthevelocity-inletboundary.Threescalerationumericalmodelsλ=1,20and300wereselected,whichthescaleratioisthesizeratioofnumericalmodelstotheexperimentalmodel.Thecomparisonsbetweenthenumericalandformerexperimentalresultsareperformedtoverifythefeasibilityofnumericalmethod.Thecomparisonsbetweenthenumericalandsimplifiedtheoreticalresultsareperformedtodiscusstheapplicabilityofthesimplifiedtheoreticalmodelsummarizedfromtheloadexperiments.Firstly,thenumericalresultsofλ=1numericalmodelshowedagoodagreementwithformerexperimentalandsimplifiedtheoreticalresults.ItisfeasibletosimulatetheISWsloadsonFPSObythenumericalmethod.Secondly,thecomparisonsbetweentheresultsofthreescalerationumericalmodelsandexperimentalresultsindicatedthatthescaleratioshavemoresignificantinfluenceontheexperimentalhorizontalforcesthantheverticalforces.Thescaleeffectofhorizontalforcesmainlyresultsfromthedifferentviscosityeffectsassociatedwiththemodel’sdimension.Finally,throughthecomparisonsbetweenthenumericalandsimplifiedtheoreticalresultsforthreescaleratiomodels,thesimplifiedtheoreticalmodelofthepressuredifferenceandfrictionforcesexertedbyISWsonFPSOisappliedforlarge-scaleorfull-scaleFPSO.

  • 标签: scale effect FPSO internal SOLITARY wave
  • 简介:Throughthehydrogenationexperimentsforremovalofolefinimpuritiesineffluentmixtureobtainedfromalkylationreactorforlinearalkylbenzenesynthesis,thereactionkineticswasstudied.TheexperimentalresultsshowedthatthecatalyticactivityofPd/Al2O3amongfourkindsofcatalystswasthehighest,andtheolefinconversionreached100%whenthereactiontemperaturewashigherthan140℃.Thekineticmodelwasestablishedthroughparametersestimation.Theexperimentalvalidationofthekineticmodelshowedthatthekineticmodelhadhighersimulationaccuracy.Theresultsofpredictionbythekineticmodelindicatedthatwiththeintensificationofreactionconditions,theolefinconversionwouldincreaseandthebromineindexofthelinearalkylbenzenewoulddecrease.UndertheconditionscoveringaWHSVof2.0h-1,atemperatureof90℃,andahydrogenpartialpressureof1.5MPa,theolefinconversionwas99.67%,andthebromineindexofthelinearalkylbenzenecouldbereducedtolessthan20.00mgBr/(100g).

  • 标签: HYDROGENATION reaction kinetics linear ALKYLBENZENE REMOVAL
  • 简介:Environmentalloadistheprimaryfactorinthedesignofoffshoreengineeringstructuresandoceancurrentistheprincipalenvironmentalloadthatcausesunderwaterstructuralfailure.Incomputationalanalysis,thecalculationofcurrentloadismainlybasedonthecurrentprofile.Thecurrentprofilemodel,whichisbasedonastructuralfailurecriterion,isconducivetodecreasingtheuncertaintyofthecurrentload.Inthisstudy,weusedprototypemonitoringdataandtheempiricalorthogonalfunction(EOF)methodtoinvestigatethecurrentprofileintheSouthChinaSeaanditscorrelationwiththedesignofunderwaterstructuralstrengthandthedynamicdesignoffatigue.Theunderwaterstructuralstrengthdesigntakesintoaccountthesizeofthestructureandtheservicewaterdepth.Weproposeprofilesfortheoverallandlocaldesignsusingtheinversefirst-orderreliabilitymethod(IFORM).Weextractedthecharacteristicprofilecurrent(CPC)ofthemonitoredseaareatosolvedynamicdesignproblemssuchasvortex-inducedvibration(VIV).WeusedrandomsamplingtoverifythefeasibilityofusingtheEOFmethodtocalculatetheCPCfromthecurrentdataandidentifiedthemainproblemsassociatedwithusingtheCPC,whichdeservecloseattentioninVIVdesign.Ourresearchconclusionsprovidedirectreferencesfordeterminingcurrentloadinthisseaarea.Thisanalysismethodcanalsobeusedintheanalysisofotherseaareasorfieldvariables.

  • 标签: CURRENT PROFILE model failure criteria PROTOTYPE
  • 简介:Theaccuracyoflaser-inducedbreakdownspectroscopy(LIBS)quantitativemethodisgreatlydependentontheamountofcertifiedstandardsamplesusedfortraining.However,inpracticalapplications,onlylimitedstandardsampleswithlabeledcertifiedconcentrationsareavailable.Anovelsemi-supervisedLIBSquantitativeanalysismethodisproposed,basedonco-trainingregressionmodelwithselectionofeffectiveunlabeledsamples.Themainideaoftheproposedmethodistoobtainbetterregressionperformancebyaddingeffectiveunlabeledsamplesinsemi-supervisedlearning.First,effectiveunlabeledsamplesareselectedaccordingtothetestingsamplesbyEuclideanmetric.Twooriginalregressionmodelsbasedonleastsquaressupportvectormachinewithdifferentparametersaretrainedbythelabeledsamplesseparately,andthentheeffectiveunlabeledsamplespredictedbythetwomodelsareusedtoenlargethetrainingdatasetbasedonlabelingconfidenceestimation.Thefinalpredictionsoftheproposedmethodonthetestingsampleswillbedeterminedbyweightedcombinationsofthepredictionsoftwoupdatedregressionmodels.Chromiumconcentrationanalysisexperimentsof23certifiedstandardhigh-alloysteelsampleswerecarriedout,inwhich5sampleswithlabeledconcentrationsand11unlabeledsampleswereusedtotraintheregressionmodelsandtheremaining7sampleswereusedfortesting.Withthenumbersofeffectiveunlabeledsamplesincreasing,therootmeansquareerroroftheproposedmethodwentdownfrom1.80%to0.84%andtherelativepredictionerrorwasreducedfrom9.15%to4.04%.

  • 标签: LIBS EFFECTIVE unlabeled samples CO-TRAINING SEMI-SUPERVISED
  • 简介:ThepolycrystallinephaseWO3/g-C3N4wassynthesizedunderstirringusingtungstenicacid(H2WO4)andgraphiticcarbonnitride(g-C3N4)asrawmaterials.ThecatalystwascharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),energydispersivespectroscopy(EDS),theFouriertransforminfraredspectroscopy(FT-IR),andtheBrunauer-Emmett-Telleranalysis(BET).ThepolycrystallinephaseWO3/g-C3N4wasdeterminedbyXRDtechnique.TheoxidativedesulfurizationprocesswasinvestigatedusingWO3/g-C3N4asthecatalyst,30%hydrogenperoxide(H202)astheoxidant,and1-butyl-3-methylimidazoliumtetrafluoroborate([bmim]BF4)ionicliquids(ILs)astheextractant.Theoperatingconditions,includingH2WO4amount,ILdose,H2O2volume,temperature,catalystdosage,andtypesofsulfurcompounds,weresystematicallyresearched.Thedesulfurizationratecouldreach98.46%forremovingdibenzothiophene(DBT)fromthemodeloilunderoptimalreactionconditions.Inaddition,thecatalyticactivitywasslightlydecreasedafterfiverecyclesofcatalysts.Thereactionkineticsanalysisshowsthattheoxidativedesulfurizationsystemwasinaccordwiththefirst-orderreactionkineticsequation.Themechanismofoxidativedesulfurizationwasproposed.

  • 标签: oxidative DESULFURIZATION WO3/g-C3N4 heterogeneous CATALYSIS EXTRACTANT
  • 简介:WehavecomprehensivelyinvestigatedthefrustratedJ1-J2-J3Heisenbergmodelonasimplecubiclattice.Thismodelallowsthreeregimesofmagneticorder,viz.,(π;π;π),(0;π;π)and(0;0;π),denotedasAF1,AF2,andAF3,respectively.Theeffectsoftheinterplayofneighboringcouplingsonthemodelarestudiedintheentiretemperaturerange.Thezerotemperaturemagneticpropertiesofthismodelarediscussedutilizingthelinearspinwave(LSW)theory,nonlinearspinwave(NLSW)theory,andGreen’sfunction(GF)method.ThezerotemperaturephasediagramsevaluatedbytheLSWandNLSWmethodsareillustrated,andareobservedtoexhibitdifferentparameterboundaries.Incertainregionsandalongtheparameterboundaries,thepossiblephasetransformationsdrivenbytheparametersarediscussed.TheresultsobtainedusingtheLSW,NLSW,andGFmethodsarecomparedwiththoseobtainedusingtheseriesexpansion(SE)method,andareobservedtobeingoodagreementwhenthevalueofJ2isnotclosetotheparameterboundaries.ThegroundstateenergiesobtainedusingtheLSWandNLSWmethodsareclosetothatobtainedusingtheSEmethod.Atfinitetemperatures,onlytheGFmethodisemployedtoevaluatethemagneticproperties,andthecalculatedphasediagramisobservedtobeidenticaltotheclassicalphasediagram.Theresultsindicatethatattheparameterboundaries,atemperature-drivenfirst-orderphasetransitionbetweenAF1andAF2mayoccuralongtheboundaryline.AlongtheAF1-AF3andAF2-AF3boundarylines,AF3islessstablethanAF1andAF2.OurcalculatedcriticaltemperatureagreeswiththatobtainedusingMonteCarlosimulationsandpseudofermionfunctionalrenormalizationgroupscheme.

  • 标签: QUANTIZED SPIN models quantum phase TRANSITIONS