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15 个结果
  • 简介:Asymmetrictree-likebranchednetworksareexploredbygeometricalgorithms.Basedonthenetwork,ananalysisofthethermalconductivityispresented.Therelationshipbetweeneffectivethermalconductivityandgeometricstructuresisobtainedbyusingthethermal-electricalanalogytechnique.Inallstudiedcases,aclearbehaviourisobserved,whereangle(δ,θ)amongparentbranchingextendedlines,branchesandparameterofthegeometricstructureshavestrongereffectsontheeffectivethermalconductivity.Whentheangleδisfixed,theopticaldiameterratioβisdependentonangleθ.Moreover,γandmarenotrelatedtoβ.Thelongerthebranchis,thesmallertheeffectivethermalconductivitywillbe.Itisalsofoundthatwhentheangleθ<δ/2,thehighertheiterationmis,thelowerthethermalconductivitywillbeandittendstozero,otherwise,itisbiggerthanzero.Whenthediameterratioβ1<0.707andangleδisbigger,theoptimalkoftheperfectratioincreaseswiththeincreaseoftheangleδ;whenβ1>0.707,theoptimalkdecreases.Inaddition,theeffectivethermalconductivityisalwayslessthanthatofsinglechannelmaterial.Thepresentresultsalsoshowthattheeffectivethermalconductivityoftheasymmetrictree-likebranchednetworksdoesnotobeyMurray'slaw.

  • 标签: 有效导热系数 网络 树形 几何结构 几何算法 行为观察
  • 简介:Theeffectofnanoparticleaggregationonthethermalconductivityofnanocompositesornanofluidsistypicallynonnegligible.Auniversalmodel(Maxwellmodel)includingnanoparticleaggregationismodifiedinordertopredictthethermalconductivityofnanocompositesmoreaccurately.Thepredictedthermalconductivitiesofsilicaandtitaniananoparticlepowdersarecomparedfirstwiththatmeasuredbyahot-wiremethodandthenwiththoseinpreviousexperimentalworks.Theresultsshowthatthereisgoodagreementbetweenourmodelandexperiments,andthatnanoparticleaggregationinananocompositeenhancesthethermalconductivitygreatlyandshouldnotbeignored.Becauseitconsiderstheeffectofaggregation,ourmodelisexpectedtoyieldprecisepredictionsofthethermalconductivityofcomposites.

  • 标签: 纳米复合材料 通用模型 聚集作用 热导率 复合纳米粒子 二氧化钛纳米粉
  • 简介:Thetwo-dimensionalRayleigh-Taylorinstabilityproblemissimulatedwithamultiple-relaxation-timediscreteBoltzmannmodelwithagravityterm.Viscosity,heatconductivity,andPrandtlnumberef-fectsareprobedfrommacroscopicandnonequilibriumviewpoints.Inthemacrosense,bothviscosityandheatconductionshowasignificantinhibitoryeffectinthereaccelerationstage,whichismainlyachievedbyinhibitingthedevelopmentoftheKelvin-Helmholtzinstability.Beforethis,thePrandtlnumbereffectisnotsensitive.Viscosity,heatconductivity,andPrandtlnumbereffectsonnonequilib-riummanifestationsandthedegreeofcorrelationbetweenthenonuniformityandthenonequilibriumstrengthinthecomplexflowaresystematicallyinvestigated.

  • 标签: discrete BOLTZMANN model/method multiple-relaxation-time RAYLEIGH-TAYLOR instability nonequilibrium
  • 简介:我们在场为聚合物的有效热传导性(等等)的一个实验模型合成那在填料尺寸分发上包括相关性—选择为Rosin-Rammler分发。等等基于某些假设被决定,到一个模型的连接真实合成材料A的行为合成材料B,充满了单音维的填料。到为等等的马模型的这些假设的申请被介绍。新模型和它的典型方程的确认从参考用试验性的数据被执行。比较由使用尺寸分发法律显示出那一很好在新模型(为ETC的尺寸分发模型)和参考的方程之间合适试验性的结果被获得甚至为大量的部分,大约多达50%。

  • 标签: 有效导热系数 粒度分布法 复合聚合物 Maxwell模型 填料 高分子复合材料
  • 简介:基于靠近房间的铝泡沫的内部结构的特征,这份报纸试图说明重建的过程靠近房间的铝的内部结构在Monte-Carlo方法和重建的模型的分数维的特征起泡沫。而且,二进制数组方法被分析重建的模型建议,靠近房间的铝泡沫的热传导性模型被建立。同时,有不同的孔的泡沫材料的热传导性被二进制数组方法计算,并且计算的值在引用与试验性的结果与一致,它证明这些方法的正确性。

  • 标签: 闭孔泡沫铝 导热系数 分形结构 重构 蒙特卡罗方法 内部结构
  • 简介:Alloymaterialshaveattractedincreasingattentionsbecausetheypossesssuperiorelectricalconductivitywhichcancontributetoexcellentelectrochemicalperformance.HereinadendriticNi3Calloymaterialhasbeenpreparedbythepyrolysisofnickelacetylacetonateemployingoleylamineasareductantand1-octadeceneoroctadecaneasthesolvent.Thecurrent–voltagecurvesindicatingthattheelectricalconductivityofNi3Cishigherthanthatofnickeloxide.Electrochemicaltestingindicatesthatahighspecificcapacityof390C/gisfoundinalkalineelectrolyteat0.5A/g,anddeliverexcellentratecharacteristicaswellascyclelife.Theexcellentelectrochemicalperformancemaybeattributedtoitshighelectricalconductivityanddendriticnanostructurethatcanpromotediffusionofelectrolyteions.Inaddition,theAC//Ni3Casymmetricsupercapacitorhasbeenassembledatacellvoltagesbetween0and1.6V,achievingamaximumenergydensityof37Wh/kg(atapowerdensityof0.3995kW/kg),andthismanifeststhattheNi3Calloyisapromisingelectrodematerialforelectrochemicalenergystorage.

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  • 简介:Inthispaper,anewmeasurmenttechniquefordeterminingthermalconductivityofsemitransparentmediainthetemperaturerange300-800Kisreported.TheexperimentalsetupisbasedonthesteppowerforcedtransienthotwiretechniqueItisassumedthattheradiativecontributiontotheheattransferprocessarisesfromemission,Notfromabsorption.Inthiscase,applicationofthe'thermalquadruples'methodallowsaverysimpleconstructionofanalyticalmodelsoftheexperimentalsetup.Theparametersensityvityanalysisdemonstratesthatthethermalconductivityofsemitransparentmeidiacanbedeterminedfromthehotwiretemperatureresponse,Theexperimentalresultsofakindofglassbetween300and800Karepresented.

  • 标签: 半透明介质 热导率 热线法
  • 简介:现在的学习在拉长的柱体上面对magnetohydrodynamics和热产生/吸收系数在威廉森液体的停滞点流动上揭示homogeneous/hetereogeneous反应的效果。进一步,可变热电导率和热层化的效果也被考虑。管理部分微分方程在类似转变的帮助下被变换成平常的微分方程。系统联合了非线性的平常的微分方程然后被射击解决技术。MATLAB射击代码被比较在限制情况与以前出版的工作验证。当现在的结果与MATLAB内建的功能bvp4c相比时,结果进一步被加强。突出的参数的效果为速度,温度和集中侧面图形地被商讨。为不同参数的皮磨擦系数和Nusselt数字在桌子的帮助下被调查。

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  • 简介:Thelocalthermalconductivityofpolycrystallinealuminumnitride(AlN)ceramicsismeasuredandimagedbyusingascanningthermalmicroscope(SThM)andcomplementaryscanningelectronmicroscope(SEM)basedtechniquesatroomtemperature.ThequantitativethermalconductivityfortheAlNsampleisgainedbyusingaSThMwithaspatialresolutionofsub-micrometerscalethroughusingthe3ωmethod.Athermalconductivityof308W/m·Kwithingrainscorrespondingtothatofhigh-puritysinglecrystalAlNisobtained.Theslightdifferencesinthermalconductionbetweentheadjacentgrainsarefoundtoresultfromcrystallographicmisorientations,asdemonstratedintheelectronbackscattereddiffraction.Amuchlowerthermalconductivityatthegrainboundaryisduetoimpuritiesanddefectsenrichedinthesesites,asindicatedbyenergydispersiveX-rayspectroscopy.

  • 标签: 扫描电子显微镜 氮化铝陶瓷 扫描热显微镜 热导率测量 显微镜技术 互补
  • 简介:AseriesofRbxCs1-xAg4I5(x=0-1)thinfilmsweregrownbyvacuumevaporationonNaCIcrystalsubstratesat350K.Theabsorptionspectraofthesefilmsweremeasuredat80Kinthewavelengthrangefrom240nmto400nm.ItisshownthatsuperionicconductorthinfilmsofquaternarycompoundRb0.5Cs0.5Ag4I5andternarycompoundRbAg415canbeobtainedatx=0.5-0.6andx=0.7-1,respectively.Atx=0.65,thecombinedcompoundfilmofthemixtureof30mol%RbAg4I5and70mol%Rb0.5Cs0.5Ag4I5ispresented.Then,basedonthespectralpositionsoftheA1andA2peaks,wedeterminedthattheRb0.5Cs0.5Ag4I5excitoncouplingenergyRexis0.21eV,theforbiddenzonewidthEgis3.82eVandtheexcitonradiusaexis0.70hm.Furthermore,theionicconductivitiesofsuperionicconductorthinfilmsofRbAg4I5andRb0.5Cs0.5Ag4I5andtheirmixturefilmareinvestigated,respectively,inthetemperaturerange303K-393K.

  • 标签: 吸收光谱 离子传导性 超离子导体薄膜 真空演化
  • 简介:现在的分析在非线性的热放射的影响下面经过常常动人的表面讨论伊灵·鲍威尔nanofluid的边界层流动。热和集体转移机制在身体上合适的对流边界条件下面被检验。可变热电导率和化学反应的效果也被考虑。用Homotopy分析方法(火腿)的所有深奥分布的系列答案被获得。统治嵌入的流动参数的影响通过图形的插图被讨论。在与温度的关系的热放射参数表演增加趋势介绍,这被观察。然而,化学反应参数展出减少的行为对集中分发。

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  • 简介:粉状的LiCr0.35Mn0.65O2的电的传导性在温度范围在高压力下面被测量直到26.22GPa由使用一个钻石铁砧房间的300413K。电导率和激活热含量在5.36GPa和21.66GPa不连续地变化,这被发现。在压力范围1.105.36GPa,压力增加激活热含量并且减少散布的搬运人,它最后导致传导性增加。在压力范围6.3221.66GPa和22.6026.22GPa,有压力增加的激活热含量减少,它有积极贡献到电的电导率增加。二导致压力的结构的阶段转变被发现由在原处在高压力下面X光检查衍射,它导致电导率和激活热含量的不连续的变化。

  • 标签: 电导率测量 高压力 相变行为 压力范围 活化焓 温度范围