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242 个结果
  • 简介:Inthisarticlewedefineasurfacefiniteelementmethod(SFEM)forthenumericalsolutionofparabolicpartialdifferentialequationsonhypersurfacesFinR~(n+1).ThekeyideaisbasedontheapproximationofFΓbyapolyhedralsurfaceΓ_hconsistingofaunionofsimplices(trianglesforn=2,intervalsforn=1)withverticesonF.AfiniteelementspaceoffunctionsisthendefinedbytakingthecontinuousfunctionsonΓ_hwhicharelinearaffineoneachsimplexofthepolygonalsurface.WeusesurfacegradientstodefineweakformsofellipticoperatorsandnaturallygenerateweakformulationsofellipticandparabolicequationsonΓ.Ourfiniteelementmethodisappliedtoweakformsoftheequations.Thecomputationofthemassandelementstiffnessmatricesaresimpleandstraightforward.Wegiveanexampleoferrorboundsinthecaseofsemi-discretizationinspaceforafourthorderlinearproblem.Numericalexperimentsaredescribedforseverallinearandnonlinearpartialdifferentialequations.Inparticularthepowerofthemethodisdemonstratedbyemployingit,tosolvehighlynonlinearsecondandfourthorderproblemssuchassurfaceAllen-CahnandCahn-Hilliardequationsandsurfacelevelsetequationsforgeodesicmeancuryatureflow.

  • 标签: 表面偏微分方程 表面有限元法 测地曲率 三角形表面 抛物线方程
  • 简介:Aminopropyl,ethylenediamine,ethenylandglycidoxygroupsfunctionalizednanoparticles,withaveragediametersrangingfrom4to6nmandcontaining1.17mmolofgroups/g,arereadilyobtainedfromnanodiamondsmodifiedwithsilanecouplingagent.Forthestudyofthesenanoparticles,TEM,IRS,XPS,andTGanalysismethodshavebeenused.

  • 标签: 表面改性 纳米粒子 官能团 纳米材料 XPS分析 IRS分析
  • 简介:Thetimeevolutionofoxygenplasmatreatedpolystyrene(PS)surfaceswasinvestigateduponstoringthemintheairundercontrolledhumidityconditions.Themethodsofwatercontactangle,X-rayphotoelectronspectroscopy(XPS),sumfrequencygeneration(SFG)vibrationalspectroscopy,andatomicforcemicroscopy(AFM)wereusedtoinferthesurfacepropertiesandstructure.ChemicalgroupscontainingoxygenwereformedonthePSsurfacewiththeplasmatreatment,demonstratedbywatercontactangleandXPS.Thesurfacepolaritydecayedmarkedlyontime,asassessedbysteadyincreaseinthewatercontactangleasafunctionofstoragetime,fromzerotoaround60°.Theobserveddecayisinterpretedasarisingfromsurfacerearrangementprocessestoburyingpolargroupsawayfromtheuppermostlayerofthesurfaces,whichisincontactwithair.Ontheotherhand,XPSresultsshowthatthechemicalcompositioninthefirst3nmsurfacelayerisunaffectedbythesurfaceaging,andthedepthprofileofoxygenisessentiallythesamewithtime.ApossiblechangeofPSsurfaceroughnesswasexaminedbyAFM,anditshowedthattheincreaseofwatercontactangleduringsurfaceagingcouldnotbeattributedtosurfaceroughness.Thus,itisconcludedthatsurfaceagingisattributabletosurfacereorganizationandthemotionofoxygencontaininggroupsisconfinedwithintheXPSprobingdepth.SFGspectroscopy,whichisintrinsicallyinterface-specific,wasusedtodetectthechemicalstructureofPSsurfaceatthemolecularlevelaftervariousagingtimes.Theresultsareinterpretedasfollows.DuringtheagingoftheplasmatreatedPSsurfaces,theoxygencontaininggroupsundergoreorientationprocessestowardthepolymerbulkand/orparalleltothesurface,whiletheCH2moietystandsuponthePSsurface.Ourresultsindicatethatthesurfaceconfigurationchangesdonotrequirelargelengthscalesegmentalmotionsormigrationofmacromolecules.Motionsthatareresponsibleforsurfaceconfigurationchangescoul

  • 标签: 聚苯乙烯 氧等离子体 湿度 表面处理
  • 简介:Thisreviewfocusedontherecentreportsrelatedtothefunction,characterizationandmodificationofoxygen-containingsurfacegroupsofactivatedcarbon(AC).TheOxygen-containingsurfacegroupswerebrieflydescribed,andthemostfrequentlyusedtechniquesforcharacterizationoftheoxygen-containingsurfacegroupsonACswerealsobrieflystated.Adetaileddiscussionoftheeffectsoftheoxygen-containingsurfacegroupsontheadsorptivecapacityofACwasgiven.Therecentprogressesinmodificationoftheoxygen-containingsurfacegroupsofACwerealsoreviewed.

  • 标签: 活性碳 含氧表面基团 表面化学 表面修饰 吸附能力
  • 简介:Ahybridmodeofone-andtwo-surfacemultipactoronthegrooveddielectricsurfaceisstudiedindetailusingbothananalyticalapproachandtwo-dimensionalparticle-in-cell(2DPIC)simulations.WhenthegroovewidthLeE0/(4πmef2),bothslopesmayhavethemultipactors.TheelectronsurfacedensityofthemultipactordischargehasasharpincreaseatthelengthL=eE0/(4πmef2).

  • 标签: 介质表面 混合模式 倍增 刻槽 电子密度 PIC
  • 简介:Theplasmonicnanogapantennaisanefficientradiatingorreceivingopticaldevice.Theresonancebehaviorofopticalantennasiscommonlyattributedtotheexcitationofalocalizedsurfaceplasmonresonance(LSPR),whichcanbetheoreticallydefinedasthequasi-normalmode(QNM).ToclarifythephysicaloriginoftheLSPR,webuildupananalyticalmodeloftheLSPRbyconsideringamultiplescatteringprocessofpropagativesurfaceplasmonpolaritons(SPPs)ontheantennaarms.ThemodelcancomprehensivelyreproducethecomplexeigenfrequencyandthefielddistributionofQNMsoftheantenna,unveilingthattheLSPRarisesfromaFabry–PerotresonanceofSPPs.Byfurtherapplyingthecomplexpoleexpansiontheoremofmeromorphicfunctions,thefieldoftheantennaunderilluminationbyanearbydipoleemittercanbeanalyticallyexpandedwithQNMs,whichwellpredictsthefrequencyresponseoftheenhancementfactorofradiation.ThepresentmodelestablishesexplicitrelationsbetweentheconceptsoftheLSPRandthepropagativeSPPandintegratestheadvantagesoftheFabry–PerotandQNMformalismsofnanogapantennas.

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  • 简介:柱体hydrogel在几何学简单并且容易综合,广泛地因此被用来调查hydrogel的胀大/缩小的不稳定性,许多不稳定性模式在文学被积累。不过,这种唯一的配置的不稳定性模式形成的机制充分远离是被理解。我们使用了并且延长,并且执行了抑制柱体hydrogel的胀大导致稳定性的线性不安分析聚合物胶化的最近发达的非线性的理论进圆柱的坐标。我们导出压力和联系平衡方程的增长明确的表达。我们为不稳定性的发作获得了批评条件并且在hydrogel的稳定性图上在细节探查了各种各样的参数的效果。稳定性图的变化的物理意思也被解释。

  • 标签: 不稳定性 水凝胶 非线性理论 胀缸 表面 高分子凝胶
  • 简介:PolysiliconMicroelectromechanicalsystems(MEMS)arethesubjectofintensiveresearches.SurfacechemistryandtopographyofaMEMSteststructurefabricatedatSandiaNationalLaboratory,USA,werestudiedbymeansofscanningelectronmicroscopy(SEM),X-rayphotoelectronspectroscopy(XPS)andatomicforcemicroscopy(AFM).XPSC()andSi2,spectrafromthepolysilieoncomponents,siliconnitridesubstrateandareferencesiliconwaferwerecompared.Theresultsconfirmthepresenceofaself-assembledmonolayer(SAM)ontheMEMSsurface.Anisland-likemorphologywasfoundonbothpolysiliconandsiliconnitridesurfacesoftheMEMS.Theislandstaketheformofcaps,beingupto0.5μmindiameterand20nminheight.Itisconcludedthattheco-existenceofcolumnargrowthandequiaxedgrowthduringthelowpressurechemicalvapordeposition(LPCVD)oftheselayersleadstotheobservedmorphologyandtheislandsarecapstothecolumnarstructures.

  • 标签: 微电机系统 表面性质 X射线光电子光谱 化学气相沉积 扫描电子显微镜
  • 简介:Surfaceeffectsonthepersistencelengthofquasi-one-dimensionalnanomaterialsareinvestigatedbyusingthetheoryofsurfaceelasticityandthecore–shellmodelofnanobeams.Asimpleandunifiedexpressionisprovidedtodeterminethepersistencelengthofnanowiresandnanotubeswithanyregularpolygonalcross-sections.Itisdemonstratedthatsurfaceeffectshaveadistinctinfluenceonthepersistencelengthwhenthecharacteristicsizesofmaterialsshrinktonanometers.Thisworkishelpfulnotonlyforunderstandingthesize-dependentbehaviorofnanomaterialsbutalsoforthedesignofdevicesbasedonnanotubesornanowires.

  • 标签: 表面效应 纳米管 纳米线 长度 一维纳米材料 尺寸缩小
  • 简介:为了在大气的踪迹部件,包括煤气阶段的化学过程的acoupled盒子模型,热力学的平衡处理的喷雾器,和异构的化学药品上探索异构的化学过程的可能的影响,在灰尘的表面上处理,黑碳(BC)和海盐被设置在喷雾器表面上模仿异构的化学的效果,并且分析影响异构的过程的主要因素。结果显示在空气的喷雾器表面上的异构的化学过程将影响踪迹气体例如的集中H2O2,HO2,O3,NO2,NO3,HNO3和SO2,和象SO42那样的喷雾器?,NO3吗?并且NH4+。敏感测试建议异构的进程的影响的大小强烈取决于喷雾器集中和系数在框模型使用了的表面举起。然而,异构的化学过程上的温度的影响是更加少些。HNO3的renoxification将影响象氮氧化物和臭氧那样的对流层的部件。

  • 标签: 气溶胶浓度 化学过程 表面吸收 非均相 建模 耦合模型
  • 简介:TheeffectsofσandΦmesonsonthesurfaceredshiftofaneutronstarhavebeeninvestigatedwithintheframeworkofrelativisticmeanfieldtheoryforthebaryonoctet{n,p,Λ,Σ,Σ0,Σ+,Ξ,Ξ0}system.ItisfoundthatcomparedwiththosewithoutconsideringthecontributionsofσandΦmesons,thesurfaceredshiftdecreasesandthatcorrespondingtothemaximumvalueofthemassalsodecreasesfrom0.2540to0.2236,aboutby12%.Meanwhile,itisalsofoundthatincludingσandΦmesons,theM/Randthatcorrespondingtothemaximummassdecrease.

  • 标签: 表面红移 中子星 介子 相对论平均场理论 最大值 重子
  • 简介:Solution-drivenmeshadaptationisbecomingquitepopularforspatialerrorcontrolinthenumericalsimulationofcomplexcomputationalphysicsapplications,suchasclimatemodeling.Typically,spatialadaptationisachievedbyelementsubdivision(hadaptation)withaprimarygoalofresolvingthelocallengthscalesofinterest.Asec-ond,less-popularmethodofspatialadaptivityiscalled'meshmotion'(radaptation);thesmoothrepositioningofmeshnodepointsaimedatresizingexistingelementstocapturethelocallengthscales.Thispaperproposesanadaptationmethodbasedonacombinationofbothelementsubdivisionandnodepointrepositioning(rhadaptation).Bycombiningthesetwomethodsusingthenotionofamobilityfunction,theproposedapproachseekstoincreasetheflexibilityandextensibilityofmeshmotionalgorithmswhileprovidingasomewhatsmoothertransitionbetweenrefinedregionsthanispro-ducedbyelementsubdivisionalone.Further,inanattempttosupporttherequirementsofaverygeneralclassofclimatesimulationapplications,theproposedmethodisde-signedtoaccommodateunstructured,polygonalmeshtopologiesinadditiontothemostpopularmeshtypes.

  • 标签: 表面网孔产生 网孔适应 网孔优化 气候模型
  • 简介:Inordertoestimatetheerosionratesofsomeplasmafacingcomponentmaterials,thesputteringyieldsofMo,Wanddeuterium-saturatedLibombardedbyfusionchargedparticlesarecalculatedbyapplicationofnewsputteringphysicsdescriptionmethodsbasedonthebipartitionmodelofiontransporttheory.ThecomparisonswithMontecarlocalculationandexperimentalresultsaremade.Thesedatamightbeusefultoestimatethelifetimeofplasmafacingcomponentsandtoanalysetheimpuritylevelincoreplasmaoffusionreactors.

  • 标签: 等离子体物理 溅射模型 聚变反应堆 粒子输运 蒙特卡洛模拟
  • 简介:Thispaperdemonstratesanewprocessofthephotolithographytechnology,usedtofabricatesimplyfinepatterns,byemployingsurfaceplasmoncharacter.Thesub-wavelengthperiodicsilicastructureswithuniformsilverfilmareusedastheexposuremask.Accordingtothetraditionalsemiconductorprocess,thegratingstructuresarefabricatedatexposingwavelengthof436nm.Atthesametime,itprovidesadditionalandquantitativesupportofthistechniquebasedonthefinite-differencetime-domainmethod.Theresultsoftheresearchshowthatsurfaceplasmoncharacteristicsofmetalscanbeusedtoincreasetheopticalfieldenergydistributiondifferencesthroughthesilicastructureswithsilverfilm,whichdirectlyimpactontheexposureoffollowingphotosensitivelayerindifferentregions.

  • 标签: 表面等离子体 光刻技术 有限差分时域法 半导体工艺 等离子体特性 二氧化硅
  • 简介:Thispaperreportsonalaboratory-basedstudycarriedouttoevaluatetheeffectivenessofsurfacetreatmentsonthedurabilityofconcreteandsuggestsanumberofdifferentevaluationmethodologiesforassessingtheperformanceofvarioussurfacetreatments.Durabilityofuntreatedandtreatedconcretespecimenswasevaluatedbymeasuringchloridediffusion,chargepassingcapacity,airpermeabilityandwaterabsorption.Atotalofsixconcretesurfacetreatmentswereselectedtorepresentdifferentgenerictypes,includingcoating,penetrantandmixed-usetreatments.Resultsshowthattheconcretespecimenswithacoatingprocedurehaveabetterlong-termperformanceandeffectivenessthanthespecimenswiththepenetranttreatments.Thisworkalsoindicatesthatthewettinganddryingcyclestestcanbeusedtoassesstheweatherabilityofthesurfacetreatments.TheASTMC1202andtheAutoclamairpermeabilitytestcanbeusedtoevaluatetheeffectivenessofsurfacetreatmentsquantitatively.Furtherworkisneeded,however,toassessthelongevityofthevarioussurfacetreatments.

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  • 简介:Inthispaper,anewtypeofresonantBrewsterfilters(RBF)withsurfacereliefstructureforthemultiplechannelsisfirstpresentedbyusingtherigorouscoupled-waveanalysisandtheS-matrixmethod.Bytuningthedepthofhomogeneouslayerwhichisunderthesurfacereliefstructure,themultiplechannelsphenomenonisobtained.Longrange,extremelylowsidebandsandmultiplechannelsarefoundwhentheRBFwithsurfacereliefstructureisilluminatedwithTransverseMagneticincidentpolarizationlightneartheBrewsteranglecalculatedwiththeeffectivemediatheoryofsubwavelengthgrating.Moreover,thewavelengthsofRBFwithsurfacereliefstructurecanbeeasilyshiftedbychangingthedepthofhomogeneouslayerwhileitsopticalpropertiessuchaslowsidebandreflectionandnarrowbandarenotspoiledwhenthedepthischanged.Furthermore,thevariationofthegratingthicknessdoesnoteffectivelychangetheresonantwavelengthofRBF,buthavearemarkableeffectonitslinewidth,whichisveryusefulfordesigningsuchfilterswithdifferentlinewidthsatdesiredwavelength.

  • 标签: 谐振布鲁斯特滤波器 共轭波分析 S矩阵法 有效介质理论