学科分类
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68 个结果
  • 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: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: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: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:ThecharacteristicsofsuspendedsedimentimagecanbereflectedbythecoefficientsofbiorthogonalwavelettransformofCDF(2,2).Basedonthepowerdistributionindifferentscales,anadaptivealgorithmisproposedinthispaper,wherebythecoefficientsareadjustednon-linearly.Theparticleinformationcanbewellretainedwhiletheuselessbackgroundisremoved.Inthisway,satisfactorybinaryimagecanbeobtainedforfurtheranalysisofthesedimentparticle.

  • 标签: 沉积物 悬浮图像 颗粒物 双正交微波 能量分布
  • 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:TiO2@ZrO2@Y2O3:有coremultishell结构的Eu3+合成粒子通过layer-by-layer(LBL)的联合被综合自己组装方法和一个solgel过程。获得的样品与扫描电子被描绘显微镜学(SEM),传播电子显微镜学(TEM),X光检查光电子光谱学(XPS),X光检查衍射(XRD),和荧光spectrophotometry。结果证明合成粒子有coremultishell结构,球形的形态学,和狭窄的尺寸分布。TiO2核心上的ZrO2层的存在能有效地阻止在TiO2核心和Y2O3壳之间的反应;为在在TiO2@ZrO2@Y2O3的TiO2核心和Y2O3壳之间的反应的温度:Eucoremultishell黄磷能被300提高

  • 标签: 光致发光特性 二氧化钛 氧化锆 铕核 Y2O3 纳米TiO2
  • 简介:TheinfluenceofNa2SO4ontheformationofZnOwhiskerswasinvestigatedinthispaper.ZnOwhiskerswithaspectratiosofupto50weresynthesizedbydissolvingε-Zn(OH)2precursorinNaOH/Na2SO4solutionatroomtemperature,followedbyagingoftheresultingsolutionat140℃for6h.Fouriertransforminfraredspectroscopy,Ramanspectroscopy,andX-rayphotoelectronspectroscopyanalysesrevealedthatSO42-ionswereprimarilyadsorbedonthe(100)planeoftheZnOwhiskersviaanouter-spherecomplexconfiguration(O-H…O),therebypromotingtheone-dimensionalgrowthofZnOwhiskersalongthec-axis.

  • 标签: 氧化锌晶须 硫酸钠溶液 水热合成 X射线光电子能谱分析 傅立叶变换红外光谱 ZnO晶须
  • 简介:基于各向异性非结构网格生成技术,开发了面向复杂几何和复杂湍流燃烧问题的自适应求解算法,并进行了程序代码的可靠性验证工作,展示了各向异性网格自适应算法在降低问题求解规模、提高火焰面和流场计算精度等方面的优势.应用该自适应求解技术准确捕捉到了一维预混层流火焰、二维对冲火焰和三维本生灯湍流火焰的流场信息,火焰面附近的温度、速度、组分等物理量与实验值吻合很好.对一款富油-快速混合-贫油(rich—bum,quick-mix,lean-burn,RQL)低排放发动机燃烧室进行了计算分析,发现了燃烧室内的热声不稳定现象.

  • 标签: 各向异性非结构网格 湍流燃烧 自适应求解
  • 简介:TiO2nanoparticlesweresynthesizedbyahomogeneouscontrolledprecipitationmethodusingindustrialtitaniumsulfate(Ti(SO4)2).TheobtainedpowderswerecharacterizedbyX-raydiffraction(XRD),transmissionelectronmicroscope(TEM),Fouriertransforminfraredspectroscopy(FTIR)andICPplasmaspectrometer.EDTAwasusedascomplexingagenttoimprovethepurityandtheformationofTiO2nanoparticles.Experimentalresultsindicatedthatthehigh-purityTiO2nanoparticleswere20nminmeansizeandnearlymonodispersed.

  • 标签: 二氧化钛 纳米粒子 乙二胺四乙酸 配位
  • 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
  • 简介:HomogeneousNi2+-dopedtitaniagelwassynthesizedbyasol-gelprocess,andthexerogelwasthenobtainedthroughaginganddrying,leadingtotheformationofNi/TiO2nanocompositeafterheattreatmentunderasuitablereducingatmosphere.TheresultingnanocompositewascharacterizedbyTGA-DSC,TEM,XRDandBETmethods.Theresultsshowthatthestructureandgrainsizeofthenanocompositescouldbemanipulatedbyalteringtheheat-treatmentconditions,andthatthenanocompositepossessesamesoporousstructurewithaporeradiusofca.28nmandaspecifictheanatase-rutilephasetransformation.

  • 标签: 纳米混合物 二氧化钛 二氧化镍 热处理 微观结构
  • 简介:DrivenbycuriosityaboutpossibleflightoptionsfortheChang’e-2spacecraftafteritremainsattheSun-EarthL2point,effectiveapproachesweredevelopedfordesigningpreliminaryfuel-optimalnear-Earthasteroidflybytrajectories.Theapproachesincludetheuseofmodifiedunstablemanifolds,gridsearchofthemanifolds’parameters,andatwo-impulsemaneuverfororbitalphasematchingandz-axisbiaschange,andaredemonstratedtobeeffectiveinasteroidtargetscreeningandtrajectoryoptimization.Asteroidflybysareexpectedtobewithinadistanceof2×107kmfromtheEarthowingtotheconstrainedEarth-spacecraftcommunicationrange.Inthiscase,thespacecraft’sorbitalmotionissignificantlyaffectedbythegravitiesofboththeSunandtheEarth,andtherefore,theconceptofthe"heliocentricoscillating-Keplerorbit"isproposed,becausetheclassicalorbitalelementsoftheflybytrajectoriesreferencedintheheliocentricinertialframeoscillatesignificantlywithrespecttotime.Theanalysisandresultspresentedinthisstudyshowthat,amongtheasteroidswhoseorbitsarethemostaccuratelypredicted,"Toutatis","2005NZ6",or"2010CL19"mightbeencounteredbyChang’e-2inlate2012or2013withtotalimpulseslessthan100m/s.

  • 标签: 近地小行星 飞行轨迹 地球 太阳 轨道运动 不稳定流形