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简介：Experimentsshowthatsiltsandsiltysoilsexhibitcontractionfollowedbydilationduringshearingandtheslopeoffailurelinedecreasesatlargestrains,termedasphasetransformationbehaviour.Thispaperistodevelopanewmicromechanicalstress-strainmodelthataccountsforthephasetransformationbehaviourbyexplicitlyemployingthephasetransformationlineanditsrelatedfrictionangles.Theoverallstrainincludesplasticslidingandplasticcompressionamonggrains.Theinternal-frictionangleatthephasetransformationstateandthevoidstatevariableareemployedtodescribethephasetransformationbehaviour.ThemodelisexaminedbysimulatingundrainedanddrainedtriaxialcompressiontestsperformedonPiteasilts.Thelocalstress-strainbehaviourforcontactplanesisalsoinvestigated.更多还原

简介：Inphasefieldfracturemodelsthevalueoftheorderparameterdistinguishesbetweenbrokenandundamagedmaterial.Atcrackfacestheorderparameterinterpolatessmoothlybetweenthesetwostatesofthematerial,whichcanberegardedasphases.Thecrackevolutionfollowsimplicitlyfromthetimeintegrationofanevolutionequationoftheorderparameter,whichiscoupledtothemechanicalfieldequations.Amongotherphenomenaphasefieldfracturemodelsareabletoreproducecracknucleationininitiallysoundmaterials.Fora1Dsettingithasbeenshownthatcracknucleationistriggeredbythelossofstabilityoftheunfractured,spatiallyhomogeneoussolution,andthatthestabilitypointdependsonthesizeoftheconsideredstructure.Thisworknumericallyinvestigatestowhichextendsizeeffectsarereproducedbythe2Dphasefieldmodel.Exemplarily,afiniteelementstudyoftheholesizeeffectisperformedandthesimulationresultsarecomparedtoexperimentaldata.

简介：ThepresentstudyinvestigatedtheinfluenceofhightemperatureoxidationandreductionpretreatmentsontheleachingrateofPanzhihuailmenite.Theas-pretreatedilmenitewasleachedwith20%HClat105℃.Theleachingprocesswascontrolledbythephasesandmicrostructuresthatevolvedduringthepretreatmentprocesses.Theleachingkineticsofpurehematite,ilmeniteandpseudobrookitewerecharacterizedtoclarifythephaseeffectontheiron-leachingrate;therateofironleachingoccursinthefollowingorderintheHClsolution:hematite（ferriciron）>ilmenite（ferrousiron）>>pseudobrookite（ferriciron）.Therefore,theoften-citednotionthatferrousirondissolvesfasterinHClsolutionsthanferricironwhenexplainingthepretreatmenteffectsisinaccurate.Moreover,theoxidationpretreatment（at600-1000℃for4h）cannotdestroythedensestructureofthePanzhihuailmenite.Therefore,theinfluenceexertedbytheoxidationontheleachingprocessisprimarilydeterminedbythephasechange;oxidationat600and700℃slightlyincreasedtherateofironleachingbecausetheilmenitewastransformedintohematite,whiletheoxidationat900-1000℃significantlyreducedtherateofironleachingbecauseapseudobrookitephaseformed.Thereductioneffectwassubsequentlyinvestigated;theas-oxidizedilmenitewasreducedunderH2at750℃for30min.Thereductionsignificantlyacceleratedtherateofsubsequentironleachingsuchthatnearlyalloftheironhaddissolvedafterleachingfor2hin20%HClat105℃.Thisenhancediron-leachingrateismainlyattributedtothecracksandholesthatformedduringthereductionprocess.

简介：Duetotheexistenceofspatialwalk-offand/orgroup-velocitymismatcheffects,pump-to-signalphasetransferbecomesinevitableduringparametricamplification.Weexperimentallydemonstratethatinhybridseededopticalparametricamplifiers(OPAs)thatincludetwoOPAstagesseededbythesignalandidlerwaves,respectively,thephaseoftheoutputsignalcanberestoredtoitsinitialvalue,althoughtherearespatialandtemporalphasefluctuationsonthepumpsource.Thismethodsignificantlyrelaxestherequirementforhighpumpbeamquality,whichisalwaysverystringentinparametricamplificationsystems.Withtheintroductionofthisschemeintobirefringentphase-matchingOPAsorchirped-pulseOPAs,itshouldbepromisingtoachieveintensefemtosecondlaserpulsesthatareclosetothediffractionlimitinspaceandultra-highcontrastintime,simultaneously.

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简介：Inresponsetothechallengeinherentinclassicalhigh-dimensionalmodelsofrandomgroundmotions,afamilyofsimulationmethodsfornonstationaryseismicgroundmotionswasdevelopedpreviouslythroughemployingawave-grouppropagationformulationwithphasespectrummodelbuiltuponthefrequencycomponents’starting-timeofphaseevolution.Thepresentpaperaimsatextendingtheformulationtothesimulationofnon-stationaryrandomseismicgroundmotions.ThegroundmotionrecordsassociatedwithN–ScomponentofNorthridgeEarthquakeatthetype-IIsiteareinvestigated.Thefrequencycomponents’starting-timeofphaseevolutionofisidentifiedfromthegroundmotionrecords,andisprovedtoadmittheGammadistributionthroughdatafitting.Numericalresultsindicatethatthesimulatedrandomgroundmotionfeatureszeromean,non-stationary,andnon-Gaussianbehaviors,andthephasespectrummodelwithonlyafewstarting-timesofphaseevolutioncouldcomeupwithasoundcontributiontothesimulation.更多还原

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简介：Asoneofcandidatesforthefuelcladdingorstructurematerialusedinfourthgenerationfissionandfusiondemonstratereactor,MAXphasehasthepropertiesofbothceramicandmetal,suchashighmeltingpoint,hightemperaturestability,gooderosionresistanceandradiation-damagetolerance[1;2].Maxphaseisaseriesofceramicsofnanolamellarandhexagonalstructure.Mrepresentstransitionelement.Arepresentsthethirdorfourthmaingroupelement.XrepresentNandC.Inthedesignoflead-cooledfastreactor,itisrequiredthatthematerialshouldendurethecorrosionofliquidPb-Bialloy.Therefore,understandingoftheoxidelayersandtheirgrowthmechanismsinLBEisfundamentallyimportantforthedevelopmentofcandidatematerials.

简介：Themainpurposeofthisstudyistosurveynumericallycomparisonoftwophaseandsinglephaseofheattransferandflowfieldofcopper-waternanofluidinawavychannel.Thecomputationalfluiddynamics(CFD)predictionisusedforheattransferandflowpredictionofthesinglephaseandthreedifferenttwo-phasemodels(mixture,volumeoffluid(VOF),andEulerian).Theheattransfercoefficient,temperature,andvelocitydistributionsareinvestigated.Theresultsshowthatthedifferencesbetweenthetemperaturefieldinthesinglephaseandtwo-phasemodelsaregreaterthanthoseinthehydrodynamicfield.Also,itisfoundthattheheattransfercoefficientpredictedbythesinglephasemodelisenhancedbyincreasingthevolumefractionofnanoparticlesforallReynoldsnumbers;whileforthetwo-phasemodels,whentheReynoldsnumberislow,increasingthevolumefractionofnanoparticleswillenhancetheheattransfercoefficientinthefrontandthemiddleofthewavychannel,butgraduallydecreasealongthewavychannel.

简介：Asupercriticalcarbondioxide(ScCO2)assistedphaseinversionwasdevelopedtoproducemicroporouspoly(vinylidenefluoride)(PVDF)membraneswhosemorphologycharacteristicsarisefrombothliquid-liquiddemixingandsolid-liquiddemixing(crystallization).ThisresultwasconfirmedbyFouriertransforminfraredspectroscopy(FTIR),fromwhichbothαandβcrystalswerefound.Asrevealedbycontactangleexperiment,thePVDFmembranespreparedviaScCO2assistedphaseinversionweremorehydrophobiccomparedwiththecontrolmembraneproducedviaconventionalimmersionprecipitationtechnique.Inparticular,thesamplewith15wt%PVDFpreparedat45°Cand13MPaexhibitedacontactangleof142°,whichwasmainlycausedbythemultilevelmicro-andnano-structure.Theeffectsofpolyethyleneglycol(PEG),polyvinylpyrrolidone(PVP)andlithiumchloride(LiCl)onthestructuresandcrystalformwereinvestigated.PVPpromotedtheformationofβphasecrystalform,whilePEGbooststheevolutionofαphase.LiClrestrainedthecrystallizationdegreeofPVDFmembraneunderScCO2.

简介：Weinvestigatetheeffectsofspontaneouslygeneratedcoherence(SGC)onboththesteadyandtransientgainpropertiesinafour-levelinverted-Y-typeatomicsysteminthepresenceofaweakprobe,twostrongcoherentfields,andanincoherentpump.Forthesteadyprocess,wefindthattheinversionlessgainmainlyoriginsfromSGC.Inparticular,wecanmodulatetheinversionlessgainbychangingtherelativephasebetweenthetwofields.Moreover,theamplitudeofthegainpeakcanbeenhancedandtheadditionalgainpeakcanappearbychangingthedetuningofthecouplingfield.Asforthetransientprocess,thetransientgainpropertiescanalsobedramaticallyaffectedbytheSGC.ComparedtothecasewithoutSGC,thetransientgaincanbegreatlyenhancedwithcompletelyeliminatedtransientabsorptionbychoosingtheproperrelativephasebetweenthetwofields.Andtheinverted-Y-typesystemwithSGCcanbesimulatedinbothatomicandsemiconductorquantumwellsystemsavoidingtheconditionsofSGC.

简介：与gigapores和meso-macropores包含层次bimodal毛孔结构的多孔的聚合物祷告(PPB)被导致聚合的阶段分离(果仁)和乳剂模板技术在一只杯子里准备毛状的microfluidic设备(GCMD)。制造过程由使乳化包含了water-in-oil乳剂的准备水的答案进包含porogen的单体答案。乳剂被增加进GCMD制作(water-in-oil)-in-water两倍乳剂微滴。搬运人的流动率连续阶段强烈影响了形成机制和微滴的尺寸。从滴下到微滴的jetting和尺寸转变的形成机制随搬运人的流动率的增加从550m减少了到250m连续阶段。准备微滴为聚合被开始由联机对形式PPB紫外照耀。因为从乳剂模板获得的porogen和gigapores的存在，在这些祷告的meso-macropores被果仁产生。毛孔形态学和PPB的毛孔尺寸分发被扫描电子显微镜学和水银侵入porosimetry(MIP)广泛地调查。因为在乳剂和搬运人的水阶段之间的不同osmolarities，新毛孔形态学在与传统的理论不同的祷告的边被形成连续阶段。bimodal毛孔结构的形态学和比例能被改变porogen的类型和数量调节。

简介：Carbondioxidetransformationtofuelsorchemicalsprovidesanattractiveapproachforitsutilizationasfeedstockanditsemissionreduction.Herein,wereportagas-phaseelectrocatalyticreductionofCO_2inanelectrolyticcell,constructedusingphosphoricacid-dopedpolybenzimidazole(PBI)membrane,whichallowedoperationat170°C.Pt/CandPtMo/CwithvariableratioofPt/Mowerestudiedasthecathodecatalysts.TheresultsshowedthatPtMo/CcatalystssignificantlyenhancedCOformationandinhibitedCH_4formationcomparedwithPt/Ccatalyst.CharacterizationbyX-raydiffraction,X-rayphotoelectronspectroscopyandtransmissionelectronmicroscopyrevealedthatmostMospeciesexistedasMoO_3inPtMo/CcatalystsandtheinteractionbetweenPtandMoO_xwaslikelyresponsiblefortheenhancedCOformationratealthoughthesebicomponentcatalystsingeneralhadalargerparticlesizethanPt/Ccatalyst.

简介：Wereportanovelapproachtoobtainingaclassicalblue-greenexcitableCaS:Eu2+phosphorwithdesiredredemissionbymicrowave(MW)firingprocedureintheabsenceofaddingelementalsulphur.ThedisturbingeffectofMWelectromagneticfieldondecompositionofCaSO4intoCaSactivatedbyeuropiumisdistinctlyobservedtogivepurehostphasewithoutaddinganyelementalsulphurandcarbon.ThehostphaseevolutionisobservedtobehighlydependentonthevariationofappliedMWpowerfromX-raydiffraction(XRD)patternsandthecorrespondingphotoluminescence(PL),andamaximumPLintensityat1100WofMWpowerisacquiredfortheobtainedpurerhostphase.Thenon-thermalandnon-equilibriumeffectsbyMWarerevealedtocorrelatewiththeinteractionbetweenpolarstructureofthehostandappliedelectromagneticfield.Theresultsdemonstrateanoptionalproceduretopreparethisred-emittingphosphorinaneffective,environment-friendlyandscalableapproachforphosphorproductionintheapplicationofbio-illuminationforplantcultivationandartificialphotosynthesis.