简介:U-shapedmicro-nanochannelscangeneratesignificantflowdisturbanceaswellaslocallyamplifiedelectricfield,whichgivesitselfpotentialtobemicrofluidicmixers,electrokineticpumps,andevencelllysisprocess.NumericalsimulationisutilizedinthisworktostudythehiddencharacteristicsoftheU-shapedmicro-nanochannelsystem,andtheeffectsofkeycontrollingparameters(theexternalvoltageandpressure)onthedeviceoutputmetrics(current,maximumvaluesofelectricfield,shearstressandflowvelocity)wereevaluated.Alargeportionofcurrentflowingthroughthewholesystemgoesthroughthenanochannels,ratherthanthemiddlepartofthemicrochannel,withitsvalueincreasinglinearlywiththeincreaseofvoltage.Duetothelocaliondepletionnearmicro-nanofluidicjunction,significantlyenhancedelectricfield(asmuchas15foldatV=1VandP0=0)aswellasstrongshearstress(leadingtoelectrokineticflow)isgenerated.Withincreasingexternalpressure,bothelectricfieldandshearstresscanbeincreasedinitially(duetoshorteningofdepletionregionlength),butaresuppressedeventuallyathigherpressureduetothedestructionofiondepletionlayer.Insightsgainedfromthisstudycouldbeusefulfordesigningnonlinearelectrokineticpumpsandothersystems.
简介:Perovskite-typeLa1-xCexMnO3(x=0-10%)catalystswerepreparedbyflamespraypyrolysisandtheiractivitiesduringthecatalyticoxidationofbenzenewereexaminedoverthetemperaturerangeof100-450℃.ThestructuralpropertiesandreducibilityofthesematerialswerealsocharacterizedbyX-raydiffraction(XRD),N2adsorption/desorption,H2temperature-programmedreduction(H2-TPR)andX-rayphotoelectronspectroscopy(XPS).TheincorporationofCewasfoundtoimprovethebenzeneoxidationactivity,andtheperovskiteinwhichxwas0.1exhibitedthehighestactivity.Phasecompositionandsurfaceelementalanalysesindicatedthatnon-stoichiometriccompoundswerepresent.TheincorporationofCehadanegligibleeffectonthespecificsurfaceareaoftheperovskitesandhencethisfactorhaslittleimpactonthecatalyticactivity.IntroductionofCe44+resultedinmodificationofthechemicalstatesofbothB-siteionsandoxygenspeciesandfacilitatedthereducibilityoftheperovskite.ThesurfaceMn4+/Mn3+ratiowasincreasedasaresultofCe4+substitution,whileadecreaseinthesurface-adsorbedO/latticeO(Oads/Olatt)ratiowasobserved.Therelationshipbetweenthesurfaceelementalratiosandcatalyticactivitywasestablishedtoallowabetterunderstandingoftheprocessbywhichbenzeneisoxidizedoverperovskites.
简介:ThisisoneoftheapplicationsofPart(Ⅰ),inwhichtheangularstiffness,andthecorrespondingstressdistributionsofU-shapedbellowswerediscussed.Thebellowswasdividedintoprotrudingsections,concavesectionsandringplatesforthecalculationthatthegeneralsolution(Ⅰ)withitsreducedformtoringplateswereusedrespectively,butthecontinuityofthesurfacestressesandthemeridianrotationsateachjointofthesectionswereentirelysatisfied.Thepresentresultswerecomparedwiththoseoftheslenderringshellsolutionproposedearlierbytheauthors,thestandardsoftheExpansionJointManufacturersAssociation(EJMA),theexperimentandthefiniteelementmethod.Itisshownthatthegoverningequationandthegeneralsolution(Ⅰ)areveryeffective.
简介:Thispaperfollowstheworkof[1,2].Therearesomeprogressindealingwithmoderatelysmallrotations(thesquaresofrotationanglesaretheorderofmagnitudeofstrains)ofmiddlesurfacenormalsofinsideandoutsideringshellsandcompressedangleofbellows.Calculationresultsagreewithexperimentswell.Tobellowdesign,themethodgiveninthispaperisofpracticalvalueandthediscussionoftheinfluenceofcompressedangleoncharacteristicrelationishelpful.
简介:基于状态空间模型的许多传统滤波算法都基于Rn空间中的高斯分布模型,但当状态向量中包含角变量或方向变量时,难以达到理想的效果。针对J.T.Horwood等提出的nS?R流形上的GaussVonMises(GVM)多变量概率密度分布,扩展了狄拉克混合逼近方法,给出了联合分布的GVM逼近方法,推导了后验分布的GVM参数计算公式,设计了量测更新状态估计算法。将J.T.Horwood等的时间更新算法与所提出的量测更新算法相结合,可实现基于GVM分布的递推贝叶斯滤波器(GVMF)。仿真结果表明,当状态向量符合GVM概率分布模型时,GVMF对角变量的估计明显优于传统的扩展卡尔曼滤波器。