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.
简介:Theeffectofnanoparticleaggregationonthethermalconductivityofnanocompositesornanofluidsistypicallynonnegligible.Auniversalmodel(Maxwellmodel)includingnanoparticleaggregationismodifiedinordertopredictthethermalconductivityofnanocompositesmoreaccurately.Thepredictedthermalconductivitiesofsilicaandtitaniananoparticlepowdersarecomparedfirstwiththatmeasuredbyahot-wiremethodandthenwiththoseinpreviousexperimentalworks.Theresultsshowthatthereisgoodagreementbetweenourmodelandexperiments,andthatnanoparticleaggregationinananocompositeenhancesthethermalconductivitygreatlyandshouldnotbeignored.Becauseitconsiderstheeffectofaggregation,ourmodelisexpectedtoyieldprecisepredictionsofthethermalconductivityofcomposites.
简介:Thetwo-dimensionalRayleigh-Taylorinstabilityproblemissimulatedwithamultiple-relaxation-timediscreteBoltzmannmodelwithagravityterm.Viscosity,heatconductivity,andPrandtlnumberef-fectsareprobedfrommacroscopicandnonequilibriumviewpoints.Inthemacrosense,bothviscosityandheatconductionshowasignificantinhibitoryeffectinthereaccelerationstage,whichismainlyachievedbyinhibitingthedevelopmentoftheKelvin-Helmholtzinstability.Beforethis,thePrandtlnumbereffectisnotsensitive.Viscosity,heatconductivity,andPrandtlnumbereffectsonnonequilib-riummanifestationsandthedegreeofcorrelationbetweenthenonuniformityandthenonequilibriumstrengthinthecomplexflowaresystematicallyinvestigated.
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.
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。
简介:Thelocalthermalconductivityofpolycrystallinealuminumnitride(AlN)ceramicsismeasuredandimagedbyusingascanningthermalmicroscope(SThM)andcomplementaryscanningelectronmicroscope(SEM)basedtechniquesatroomtemperature.ThequantitativethermalconductivityfortheAlNsampleisgainedbyusingaSThMwithaspatialresolutionofsub-micrometerscalethroughusingthe3ωmethod.Athermalconductivityof308W/m·Kwithingrainscorrespondingtothatofhigh-puritysinglecrystalAlNisobtained.Theslightdifferencesinthermalconductionbetweentheadjacentgrainsarefoundtoresultfromcrystallographicmisorientations,asdemonstratedintheelectronbackscattereddiffraction.Amuchlowerthermalconductivityatthegrainboundaryisduetoimpuritiesanddefectsenrichedinthesesites,asindicatedbyenergydispersiveX-rayspectroscopy.
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.
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。
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。