学科分类
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20 个结果
  • 简介:AnFEanalysisprocedurewaspresentedtopredictthebehaviorofsoilogeogridinterctionunderautomobileloading.Thedynamicinteractionsbetweenthetransversebars,thelongitudinalribsandthesoilweresimulatedbyasystemconsistingofnonlinearsprings,dashpotsandmasses,tostudythedeformationpropertiesofthereinforcedsoil.Theequivalentstiffnessanddampingratioscouldbedeterminedwiththeshakingtable.Thedynamicresponsesofareinforcedsubgradewereanalyzedwiththe3Dfiniteelementapproach.Thisapproachisprogrammedandappliedtoanalyzethesoilogeogridinteractionunderdynamicloading.Thecomparativeanalysisoftheresponseofthereinforcedsubgradeandthatofthesubgradewithoutreinforcementshowsthatthegeogridplacedatthebottomofthebaselayermayeffectivelyreducetheaccumulativeplasticdeformationduetothecyclicautomobileloading.

  • 标签: 道路力学 车辆负载 路基加固 变形 弹性减阻装置系统
  • 简介:Uniformlysizedα-Fe2O3hexagonalplateletsweresynthesizedbyahydrothermalprocessusingFe(OH)3suspensionandlargeamountofNaOH.ThereactionproductswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),selectedareaelectrondiffraction(SAED),andavibratingsamplemagnetometer(VSM).Theresultsshowthatthehexagonalplateletsarefine,monodisperseandconsistingofsingle-crystals.Themagnetichysteresis(M-H)curveofthesamplesmeasuredatroomtemperatureindicatesthattheα-Fe2O3micro-plateletsexhibitferromagneticbehaviorswithrelativelylowcoercivity.

  • 标签: Fe2O3 六角片状 单分散 水热法合成 振动样品磁强计 扫描电子显微镜
  • 简介:AnewapproachtoproducesuperfineWC-Copowderbydirectreductionandcarbonizationisproposed.Water-solublesaltscontainingWandCowereusedasrawmaterials.Tungstenandcobaltoxidepowder(CoWO4/WO3)wasfirstformedbyaspray-pyrolysistechnique,whichwasthenmixedwithcarbonblackandconvertedtoWC-Cocompositepowderat950℃for4hinN2atmosphere.Theresultingpowderhasaparticlesizeof100-300nm.

  • 标签: 碳化钨 碳化 合成粉末 干馏技术 高温分解 微观结构
  • 简介:Theobjectivestressrateisaratherimportantprobleminmechanicsoffinitedeformation.Inthispaper,theobjectivestressrateinco-movingcoordinateisderivedbyapplyingnonlineargeometricfieldtheoryofdeformation.Problems.suchaxlargeextensioncoupledwithrotation,andlargesheardeformation,areexemplifiedbyusingthenewformula.ComparingwithJaumann’sstressrateandotherformulaepresentedincurrentliterature,thenewresultappearstobethereasonableoneinco-movingcoordinatesystem.

  • 标签: rotation COORDINATE FORMULAE RATE decomposed FRAMES
  • 简介:Inco-ionicconductingsolidoxidefuelcell(SOFC),bothoxygenion(O2)andproton(H+)cantransportthroughtheelectrolyte,generatingsteaminboththean-odeandcathode.ThusthemasstransportphenomenonintheelectrodesisquitedifferentfromthatinconventionalSOFCwithoxygenionconductingelectrolyte(O-SOFC)orwithprotonconductingelectrolyte(H-SOFC).Thegenerationofsteaminbothelectrodesalsoaffectstheconcentrationover-potentiallossandfurthertheSOFCperformance.However,nodetailedmodelingstudyonSOFCswithco-ionicelectrolytehasbeenreportedyet.Inthispaper,anewmathematicalmodelforSOFCbasedonco-ionicelectrolytewasdevelopedtopredictitsactualperformanceconsideringthreemajorkindsofoverpotentials.Ohm'slawandtheButler-Volmerformulawereusedtomodeltheionconductionandelectrochemicalreactions,respectively.Thedustygasmodel(DGM)wasemployedtosimulatethemasstransportprocessesintheporouselectrodes.Parametricsimulationswereperformedtoinvestigatetheeffectsofprotontransfernumber(tH)andcurrentdensity(jtotal)onthecellperformance.Itisinterestingtofindthattheco-ionicconductingSOFCcouldperformbetterthanO-SOFCandH-SOFCbychoosinganappropriateprotontransfernumber.Inaddition,theco-ionicSOFCshowssmallerdifferencebetweentheanodeandcathodeconcentrationoverpotentialsthanO-SOFCandH-SOFCatcertaintHvalues.TheresultscouldhelpmaterialselectionforenhancingSOFCperformance.

  • 标签: 固体氧化物燃料电池 离子导电 电解质 数学分析 质量传递过程 电池性能
  • 简介:有从30~80nm的尺寸的Fe3O4nanoparticles被湿milling铁粉末在一家行星的球工厂综合。阶段作文和同样综合的产品的形态学被X光检查衍射(XRD)测量,扫描电子显微镜学(SEM)和传播电子显微镜学(TEM)。NanosizedFe3O4粒子被湿milling准备金属性的铁粉末(?200网孔,99%)在与不锈钢装备的一家行星的球工厂,使用的小瓶与50:1并且以300rpm的旋转速度的ball-to-powder团比率在提取的水下面熨球。在这个方法的铁球的使用在Fe3O4formation起了一个关键作用。现在的技术简单,这个过程是容易的执行。

  • 标签: 行星球磨机 湿磨法 四氧化三铁 钠米颗粒
  • 简介:AconstitutiveequationtheoryofOldroydfluidBtype,i.e.theco-rotationalderivativetype,isdevelopedfortheanisotropic-viscoelasticfluidofliquidcrystalline(LC)polymer.Analyzingtheinfluenceoftheorientationalmotiononthematerialbehaviorandneglectingtheinfluence,theconstitutiveequationisappliedtoasimplecaseforthehydrodynamicmotionwhentheorientationalcontributionisneglectedinitandtheanisotropicrelaxation,retardationtimesandanisotropicviscositiesareintroducedtodescribethemacroscopicbehavioroftheanisotropicLCpolymerfluid.UsingtheequationfortheshearflowofLCpolymerfluid,theanalyticalexpressionsoftheapparentviscosityandthenormalstressdifferencesaregivenwhichareinagoodagreementwiththeexperimentalresultsofBaeketal.Forthefiberspinningflowofthefluid,theanalyticalexpressionoftheextensionalviscosityisgiven.

  • 标签: 各向异性粘性流体 非牛顿流 各向异性材料方程 外延流 液晶聚合体
  • 简介:Multi-walledcarbonnanotubes(MWNTs)with20nmouterdiameterwerepreparedbychemicalvapordepositionofethyleneusingultrafinesurface-modifiedacicularα-Fecatalystparticles.ThegrowthmechanismofMWNTsonthelargercatalystparticlesareattributedtotheinteractionbetweentheFenanoparticleswiththesurface-modifiedsilicalayer.Thisinteraction-mediatedgrowthmechanismisillustratedbystudyingtheelectronic,atomicandcrystalpropertiesofsurface-modifiedcatalystsandMWNTsproductsbycharacterizationwithX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM),highresolutiontransmissionelectronmicroscopy(HRTEM),thermalgravimetricanalysis(TGA)andRamanspectra.

  • 标签: 碳纳米管 多壁碳纳米管 MWNTS 表面修正 成长机制 纳米材料
  • 简介:W,N共同做TiO2nanoparticles被一个solgel方法综合。准备样品被X光检查衍射(XRD)描绘,域排放扫描电子显微镜学(FE-SEM),传播电子显微镜学(TEM),Fourier变换红外线的光谱学(英尺红外),X光检查光电子光谱学(XPS)和弥漫的反射spectrophotometry(医生)。结果证明共同做的光催化剂是有22.5nm的最小的粒子尺寸的实质上一致的球形的粒子。比作未做的TiO2,N-TiO2和P-25,W的吸收边,N共同做转移到更长的波长的TiO2和它为在Xe灯(350W)下面的甲基橘子(瞬间)的降级的photocatalytic活动更高。

  • 标签: N-TiO2 光催化剂 共掺杂 场发射扫描电子显微镜 光驱动 傅里叶变换红外光谱
  • 简介:在现在的纸,最大的Lyapunov代表为一种合作尺寸被调查在上的二个分叉系统一三维中央对由围住的噪音的参量的刺激歧管、使\O遭到。由使用一个不安方法,一个一个维的阶段散开过程的不变的措施的表情为三个案例被获得,在哪个矩阵B的不同形式,那在噪音刺激术语被包括,被假定然后作为结果,为一个维的阶段散开过程的所有三种单个边界被分析。经由Monte-Carlo模拟,我们发现不变的措施的分析表情遇见数字的很好。并且而且,P分叉行为为一个维的阶段散开过程被调查。为为一个维的阶段散开过程的单个边界的三个案例,最后,最大的Lyapunov代表的分析表达式为随机的分叉系统被介绍。

  • 标签: 最大LYAPUNOV指数 有界噪声 分岔行为 系统 扩散过程 兴奋
  • 简介:这篇论文在磁铁矿(Fe3O4)的弱磁性的帮助地的合成上论述试验性的结果在一个氧化一起沉淀方法的nano粒子,与没有磁性的正式就职的盒子相比。XRD结果证明在220G下面的弱磁性的正式就职能从goethite(α-FeOOH)加速阶段转变到磁铁矿(Fe3O4),并且影响水晶结构,粒子尺寸/形态学和磁铁矿nano粒子的磁性的反应综合。另外,在合成反应的FeCl2答案的更高的集中导致了更好的粒子,有或没有磁性的正式就职。

  • 标签: 纳米粒子 辅助合成 共沉淀法 磁铁矿 弱磁场 氧化
  • 简介:Carbonnanotube(CNTs)/Fe-Ni/TiO2nanocompositephotocatalystshavebeensynthesizedbyaninsitufluidizedbedchemicalvapordeposition(FBCVD)method.ThecompositephotocatalystswerecharacterizedbyXRD,Ramanspectroscopy,BET,FESEM,TEM,UV-visspectroscopy,andXPS.TheresultsshowedthattheCNTsweregrowninsituonthesurfaceofTiO2.Fe(lll)inTiO2showednochemicalchangesinthegrowthofCNTs.Ni(Ⅱ)waspartlyreducedtometalNiintheFBCVDprocess,andthemetalNiactedasacatalystforthegrowthofCNTs.ThephotocatalyticactivitiesofCNTs/Fe-Ni/TiO2decreasedwiththeriseoftheFBCVDreactiontemperature.ForthesamplesynthesizedatlowFBCVDtemperature(500℃),morethan90%andnearly50%ofmethylenebluewereremovedunderUVirradiationin180minandundervisiblelightirradiationin300min,respectively.TheprobablemechanismofsynergisticenhancementofphotocatalysisontheCNTs/Fe-Ni/TiO2nanocompositeisproposed.

  • 标签: 纳米复合光催化剂 化学气相沉积 纳米复合材料 碳纳米管 二氧化钛 原位合成
  • 简介:PureAl2O3-2SiO2powderswerepreparedbysol-gelandcoprecipitationmethods,andtheiralkaliactivationreactivitieswerecompared.Thealkali-activationreactivityofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbythecoprecipitationmethod.Thepowderswereinvestigatedby27AIand29Simagic-anglespinningnuclearmagneticresonancespectroscopy(MASNMR)tounderstandtherelationshipbetweentheirstructureandalkali-activationreactivity.The27AlMASNMRdatashowedthatthefive-coordinateAIcontentofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbycoprecipitation.Thehighercontentoffive-coordinateAlcorrespondedtohigheralkali-activationreactivity.The29SiMASNMRdatashowedthatforthepowderpreparedbythesol-gelmethod,siliconwasreplacedbyaluminumatsecondarycoordinationsitesofthecentralSiatomsduringcalcination.However,forthepowderpreparedbysingle-batchcoprecipitation,themainchangewasfromalowdegreeofpolycondensationtoahighdegreeofpolycondensation.

  • 标签: 魔角旋转核磁共振 活化反应 固体碱 核磁共振光谱 粉末 化学合成