简介:WetheoreticallyinvestigatednegativeentropySofbiopolymerwhichpassesthroughananometerpore(suchasα-hemolysin),especiallyenteringprocessandescapingprocess,onthebasisofwhichwealsostudiedbiopolymerentering-poretimeτent,biopolymerenteringmeanvelocityvent,biopolymerescaping-poretimeτesc,andbiopolymerescapingmeanvelocityvesc,respectively.Ourresultsillustratethattheenteringandescapingprocessesofbiopolymerdependonitsnegativeentropy,andenteringprocessismoredifficultthanescapingprocessforbiopolymertranslocation.Thistremendousdifferencebetweenthetwoprocesseswillofferausefulengineeringhintforsinglemacromoleculeidentification.
简介:Thispaperproposesanautomaticmethodofporecombinationrecognition,whichisanimportantfeaturetohardwoodrecognition.Afterextractingedgefromwoodmicroscopiccross-section,basedonareahistogramofthesimilarcircleregions,themethodclassifiesallregionsintotwoclasseswithmaximumbetween-classvariance,soastodistinguishtheporefromothertextures,whicharesimilarinshapesbutdifferentinsizes.Meanwhile,secondobjectivefunctionaboutaverageareaofclosedregionsisusedtoimprovetheporesegmentationperformance.Atlast,themethodusesadjacencydegreeofporesettojudgeporecombination.Theexperimentsdemonstratethatthetaskofporesegmentationcanbecompletedsuccessfullyforallkindsofporedistributionandcombination,andalsothecorrectcombinationsofporesaregiven.
简介:DuringthereactionbetweencalciumsorbentsandSO2,calciumsorbentsarefirstcalcinedandconvertedintoCaO.CaOcanbeobtainedbycalciningCa(OH)2orCaCO3.Theporosityofthesorbentisincreasedbecauseofcalcinationandisdecreasedbecauseofsulfurization.InthecalcinationprocessH2OorCO2isescapedfromtheparticlesandporesareformedinparticles.ThereactionorconvertrateofCaOisinfluencedstronglybytheporestructurecharacters.FromCa(OH)2toCaOtheescapevelocityofH2Ooritsmasstransferisoneofthekeyfactorsinfluencingtheporeforming.Duringcalcinationprocessdifferentheatingvelocity,differentheatingtimeandtemperatureweresuggested.Thetemperaturerisingrateandcalciningtemperatureplayimportantroletotheporestructure.TheconvertratesofCaOobtainedthroughdifferentcalciningconditionswereinvestigatedexperimentally.SomeinterestingresultswereshowedthatthecalciumutilizationofCaOparticlesisdeterminednotonlybythespecialsurfaceareaandtotalporevolume,butalsobypore-sizedistribution.Themainfactorinfluencingthesulfationistheporediameterdistributionatlowersulfationtemperature.Forhigherreactiontemperaturespecificvolumeistheimportantreason.Butpore-sizedistributionisstronglyinfluencedbyheatfluxandtemperatureinthecalciningprocess.
简介:ChloridecontentandthepHvalueoftheporesolutionintheneighborhoodofsteelreinforcementaredecisiveparametersforinitiationandrateofcorrosion.Theporesolutionofcementmortarandhardenedcementpastehasbeenexpressedfromtheporespacebyhighpressureintheinvestigation.Theinfluenceofthewater-cementratio,age,andadditionofchloridetothefreshmixonchloridecontentintheporesolutionhasbeendeterminedbyionchromatography.AtthesametimethepHvalueoftheporesolutionhasbeendetermined.Thedissolvedchloridecontentdecreaseswithincreaseinthewater-cementratio.Theamountofboundchlorideincreaseswithtime,butitdecreaseswithdecreasingcontentofdissolvedchlorideintheporesolution.Asignificantinfluenceofcarbonationonthedissolvedchloridecontentoftheporesolutionhasbeenobserved.Withcompletecarbonation,thedissolvedchloridecontentincementmortarandhardenedcementpasteincreasesbyafactorbetween2and12.Theboundchloridedecreasesby27%-4%.Asexpected,thepHvaluedecreasesfromaround13.2toaslowas8.0duetocarbonation.ItcanbeconcludedthatcarbonationnotonlylowersthepHvaluebutliberatesboundchloride.Thisisoneobviousreasonwhythecombinedactionofchloridepenetrationandcarbonationacceleratessteelcorrosionandshortenstheservicelifeofreinforcedconcretestructures.
简介:Adensityfunctionaltheoryisappliedtocalculatingthelocaldensityprofilesofcolloidsconfinedinaslit-likeporeaswellastheradialdistributionfunctionsofbulkcolloids.Theinteractionbetweenthecolloidalparticlesisdescribedusingahard-coreYukawamodel.TheexcessHelmholtzenergyfunctionalisacombinationofthemodifiedfundamentalmeasuretheoryofYuandWu(2002)forthehard-corecontributionandacorrectedmean-fieldtheoryfortheattractivecontribution.ComparisonwiththeresultsfromtheMonteCarlosimulationsshowsthatthecorrectedtheoryimprovesthedensityprofilesofcolloidsinthevicinityofcontactovertheoriginalmean-fieldtheory.Boththepresentcorrectedtheoryandsimulationssuggestthattherearedepletionanddesorptionforthecolloidwithstrongattractionbetweenparticlesatlowtemperature.
简介:Inmidsummer,theChineseAssociationforInternationalUnderstanding(CAFIU)welcomedthefirstgroupofJordanguests.AttheinvitationofCAF...
简介:Byutilizinghardtemplatemethodtoadjustthemesoporelength,andalkaliactivationtogeneratemicropores,twohierarchicalporouscarbons(HPCs)wereprepared.Withcontrollingoftheirmesoporelengthandtheactivationconditions,thecomplexsystemcomposedbyHPCsandelectrolytewassimplifiedandtheeffectofmesoporelengthontheperformanceofHPCsaselectrodesinsupercapacitorswasinvestigated.Itisfoundthatwiththemesoporelengthgettingsmaller,theorderedareagetssmallerandthaggregationoccurs,whichiscausedbythehighsurfaceenergyofsmallgrains.HPCwithlongpore(HPCL)exhibitsadonut-likemorphologywithwell-definedorderedmesoporesandaregularorientationwhileinHPCwithshortpores(HPCS),shortmesoporesareonlyorderlydistributedinsmallregionsLongerorderedchannelsformunobstructedwaysforionstransportintheparticleswhileshorterchannels,onlyorderlydistributedinsmallareas,resultsinblockedpaths,whichmayhindertheelectrolytionstransport.Duetotheunobstructedstructure,HPCLexhibitsgoodratecapabilitywithacapacitancretentionrateover86%ascurrentdensityincreasingfrom50mA/gto1000mA/g.ThespecificcapacitanceofHPCLderivedfromthecyclicvoltammetrytestat10mV/sisupto201.72F/g,whilethespecificapacitanceofHPCSisonly193.65F/g.
简介:Theactivatedaluminaasacatalystcarrierwerewidelyusedinautomotiveexhaustcatalystsunderhightemperature,suchas,petroleumrefiningcatalysts,hydrogenationandhydrodesulfurizationcatalystcarrierinChinaandabroad.γ-Al2O3wasthecatalystcarrierthatwasthemostwidelyusedandthebestcarrierofimprovedspecificsurfacearea.However,theactivationofthecoatingconsistedofγ-Al2O3wereusuallytransformedintoα-Al2O3at800oC,causingincreaseddensity,reducedspecificsurfacearea,andthecollapseresultofporestructure.Whilethetemperaturereached1200oC,activationofcoatingdetachedfromthecarrier,theresistanceofflowinggasincreased,catalyticactivitydecreased.AdditionofLa2O3stabilizedtheγ-Al2O3crystalstructure,whichwouldkeeptheactivationstabilityofcoatingatahightemperatureandinhibitactivityloss.Theactivatedaluminacarriertreatedwiththesolid-pore-expandingagentcontaining[La(EDTA)]-thatsynthesizedusingsolidandsolid-hybridapproachwiththethermalstabilizerlanthanaandEDTAatthehigh-temperaturehada10-30μmlargeporeporousnetwork-likestructure,afteraluminawascalcinedat1200oCfor1h.Thespecificsurfaceareaoffourspecimenwerebeyond120m2/g,whilethesamplespecificsurfaceareaofx([La(EDTA)]-)=1%wasupto150.36m2/g.
简介:Aseriesofregularwaveexperimentshavebeendoneinalarge-scalewaveflumetoinvestigatethewave-inducedporepressurearoundthesubmarineshallowlyembeddedpipelines.Themodelpipelinesareburiedinthreekindsofsoils,includinggravel,sandandsiltwithdifferentburialdepth.Theinputwaveschangewithheightandperiod.Theresultsshowthattheamplitudesofwave-inducedporepressureincreaseasthewaveperiodincrease,anddecayfromthesurfacetothebottomofseabed.Higherporepressuresarerecordedatthepipelinetopandthelowerporepressuresatthebottom,especiallyinthesandseabed.Thenormalizedpressurearoundpipelinedecreasesastherelativewaterdepth,burialdepthorscatteringparametersincrease.Forthesiltseabed,thewavelettransformhasbeensuccessfullyusedtoanalyzethesignalsofwave-inducedporepressure,andtheoscillatoryandresidualporepressurecanbeextractedbywaveletanalysis.Higheroscillatorypressuresarerecordedatthebottomandthelowerpressuresatthetopofthepipeline.However,higherresidualpressuresarerecordedatthetopandthelowerpressuresatthebottomofthepipeline.
简介:Porestructurecharacteristicsofrockareagreatconcernforresearchersandpractitionersinrockmechanicsandrockengineeringfields.Inthisstudy,mercuryintrusionporosimetry(MIP)wasusedtomeasureporesizedistribution,aswellasseveralimportantindexparametersofporestructure,forsevencommontypesofdeepsedimentaryrockswithatotaloffiftyrocksamples.Resultsshowasimilarporesizedistributionpatternoftherocksamplesinthesamelithologicalgroup,butremarkabledifferencesamongdifferentlithologicalgroups.Amongseveninvestigatedrocktypes,mudstonehasthesmallestporosityof3.37%,whileconglomeratehasthelargestvalueof18.8%.Itisalsofoundthattheporosityofrocktypeswithfinergrainsizeislowerthanthosewithcoarsergrainsize.Meanwhile,acomparisonoffrequencydistributionattenintervalsofpore-throatdiameteramongseventypesofsedimentaryrocksrevealsthatdifferentrocktypeshavedifferentdominantpore-sizeranges.Furthermore,permeabilityoftheinvestigatedsedimentaryrocksampleswasderivedbasedonMIPdatausingreportedtheoreticalequations.Amongsevenrocktypes,mudstonehasthelowestaveragedpermeability(3.64×10-6mD)whileconglomeratehasthehighestone(8.59×10-4mD).Frommudstonetoconglomerate,rockpermeabilityincreaseswithanincreaseofgrainsize,withonlyanexceptionofsiltstonewhichhasarelativelylargerporosityvalue.Finally,regressionanalysisshowthatthereisagoodfitting(R2=0.95)betweenpermeabilityandporositywhichcouldbeeasilyusedtoderivereliablepermeabilityvaluesofsimilarkindsofengineeringrocks.
简介:Aseriesofsisalbasedactivatedcarbonfiberswerepreparedwithsteamactivationattemperaturefrom750℃to900℃.Theirporestructureswerecharacterizedthroughtheirnitrogenadsorptionisothermsat77Kusingdifferenttheories.Theresultsshowedthatt-plotmethodandDR-plotmethodcouldsuitablybeusedtocharacterizethemesoporestructureandthemulti-stagedistributionofporesizeofactivatedcarbonfibers.Italsoshowedthattheporesizewidenswiththeincreaseofactivationtemperature.
简介:Porepresureindepboreholes:ItsmeasurementandrelationwithseismicactivitiesJIANLIGAO(高建理)SHIZONGSUN(孙世宗)JIANMINDING(丁健民)GU...
简介:ThemolecularsieveVPI-5wassynthesizedbyusingvariousorganicamines(DEA,Di-PA,DBA,DPenA,TBA,DEOAandTEOA)asthestructure-directingagent.TheuseofDPAenlargedtherangeofthecrystallizationtemperaturefrom110℃to190℃inthesynthesisofVPI-5,whiletheuseofTEOAchangedthecompositionofthereactantsinabroadvariety.DiaminesarethetypicalaminesinthesynthesisofVPI-5.AmongthemDBAandDPAarethemostfavoritestructure-directingagentsforthesynthesisofVPI-5molecularsieve.
简介:Centrifugeexperimentsarecarriedouttoinvestigatetheresponsesofsuctionbucketfoundationsunderhorizontaldynamicloading.Theeffectsofloadingamplitude,thesizeofthebucketandthestructuralweightonthedynamicresponsesareinvestigated.Itisshownthat,whentheloadingamplitudeisoveracriticalvalue,thesandattheupperpartaroundthebucketsoftensorevenliquefies.Theliquefactionindex(excessporepressuredividedbyinitialeffectivestress.Inthispaper,thedevelopmentaldegreeofexcessporepressureisdescribedbyliquefactionindex)decreasesfromtheupperparttothelowerpartofthesandfoundationintheverticaldirectionanddecreasesfromneartofarawayfromthebucket′ssidewallinthehorizontaldirection.Largesettlementsofthebucketandthesandaroundthebucketareinducedbythehorizontaldynamicloading.Thedynamicresponsesofthebucketofasmallerheight(whenthediameteristhesame)areheavier.Acycliccracksomedistancenearthebucketoccursinthesand.
简介:Anumericalmethodisproposedfortheelasto-plasticityandpore-pressurecoupledanalysisonthepulloutbehaviorsofaplateanchor.Thebounding-surfaceplasticity(BSP)modelcombinedwithBiot’sconsolidationtheoryisemployedtosimulatethecyclicloadinginducedelasto-plasticdeformationofthesoilskeletonandtheaccompanyinggeneration/dissipationoftheexcessporewaterpressure.Thesuctionforcegeneratedaroundtheanchorduetothecyclicvariationoftheporewaterpressurehasmucheffectonthepulloutcapacityoftheplateanchor.Thecalculatedpulloutcapacitywiththeproposedmethod(i.e.,thecoupledanalysis)getslowerthanthatwiththeconventionaltotalstressanalysisforthecaseoflong-termsustainedloading,butslightlyhigherforthecaseofshort-termmonotonicloading.Thecyclicloadinginducedaccumulationofporewaterpressuremayresultinanobviousdecreaseofthestiffnessofthesoil-plateanchorsystem.