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500 个结果
  • 简介:PARAMETRICSURFACE/SURFACEINTERSECTIONZengXianglin;WangQifu;ZhouJi;YuJunPARAMETRICSURFACE/SURFACEINTERSECTION¥ZengXianglin;Wan...

  • 标签: PARAMETRIC SURFACE INTERSECTION SUBDIVISION SOLID MODELING
  • 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:Inthispaper,amethodtoconstructasurfacewithpointinterpolationandnormalinterpolationispresented.Analgorithmtoconstructthediscreteinterpolationisalsopresented,whichhasthetimecomplexityO(NlogN),whereNinthenumberofscatteredpoints.

  • 标签: 计算机图形学 计算机辅助设计 插值曲面
  • 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
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  • 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:不同类的表面空气放射转移的复杂性是大气的物理和大气的放射的地里的最前的问题之一。迄今为止,短波放射上的表面性质的影响很好没被学习。日报向下出现最近的FLASHFlux/CERES的短波放射(快Longwave和短波Fluxes_Time插入内推并且空间地一般水准/云并且地球绚烂的精力系统)卫星数据与被作比较在situ数据。比较显示二个数据集合之间的差别与相对扁平的地面相比在崎岖地面上不稳定、大,并且卫星产品的吝啬的绝对错误到达31.4Wm<啜class=“a-plus-plus”>在崎岖地面上的2(12.3%)。把/CERES产品基于SSF(单个卫星脚印),分发上的表面性质的影响向下,表面短波放射(DSSR)被分析。在西藏的高原上的DSSR上的表面性质的影响在附近两次在在一样的纬度(东方中国西方的和平、副热带的诺思太平洋)定位的二个另外的区域象那一样大。模拟在I3RC(三维的放射代码的国际Intercomparision)的帮助下被执行蒙特卡罗3D放射的转移社区模型。结果证明DSSR作为表面反照率增加增加。而且,如果云的空间分发是更不一致的,DSSR上的表面反照率的影响更大。这些结果将贡献放射的转移建模的3D和卫星倒置算法的改进的发展,这被希望。

  • 标签: 短波辐射 表面性质 青藏高原 大气辐射传输 地表 表面性能
  • 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:Surfacewavescompriseanimportantaspectoftheinteractionbetweentheatmosphereandtheocean,soadynamicallyconsistentframeworkformodellingatmosphere-oceaninteractionmusttakeaccountofsurfacewaves,eitherimplicitlyorexplicitly.Inordertocalculatetheeffectofwindforcingonwavesandcurrents,andviceversa,itisnecessarytoemployaconsistentformula-tionoftheenergyandmomentumbalancewithintheairflow,wavefield,andwatercolumn.Itisveryadvantageoustoapplysur-face-followingcoordinatesystems,wherebythesteepgradientsinmeanflowpropertiesneartheair-waterinterfaceinthecross-interfacedirectionmayberesolvedoverdistanceswhicharemuchsmallerthantheheightofthewavesthemselves.Wemayaccountforthewavesexplicitlybyemployinganumericalspectralwavemodel,andapplyingasuitabletheoryofwave–meanflowinteraction.Ifthemeanflowissmallcomparedwiththewavephasespeed,perturbationexpansionsofthehydrodynamicequationsinaLagrangianorgeneralizedLagrangianmeanframeworkareuseful:forstrongerflows,suchasforwindblowingoverwaves,thepresenceofcriticallevelswherethemeanflowvelocityisequaltothewavephasespeednecessitatestheapplicationofmoregeneraltypesofsurface-followingcoordinatesystem.Theinteractionoftheflowofairandwaterandassociateddifferencesintemperatureandtheconcentrationofvarioussubstances(suchasgasspecies)givesrisetoacomplexboundary-layerstructureatawiderangeofverticalscales,fromthesub-millimetrescalesofgaseousdiffusion,toseveraltensofmetresfortheturbulentEkmanlayer.Thebal-anceofmomentum,heat,andmassisalsoaffectedsignificantlybybreakingwaves,whichacttoincreasetheeffectiveareaofthesurfaceformasstransfer,andincreaseturbulentdiffusivefluxesviatheconversionofwaveenergytoturbulentkineticenergy.

  • 标签: 相互波 表面电流 湍流 坐标系统
  • 简介:Surfacenanocrystallization(SNC)hasprovedtobeaneffectiveapproachtoimprovetheoverallpropertiesofbulkmetallicmaterials.Recently,anewsurfacenanocrystallizationtechnique,i.e.,surfacemechanicalgrindingtreatment(SMGT),wasdeveloped.Inthiswork,agradientnano-microstructurewasachievedinthesurfacelayeroftheAISI52100steelbyusingSMGT.Weobtainedaminimumgrainsizeofabout7nminthetopsurfacelayer.Thetotalthicknessofthedeformedlayerisover200micrometer.Meanwhilethesurfaceroughnessisratherlow.Ferritegrainsweredeformedtodifferentextentsvaryingwithdepthfromthetopsurface.Gradientgrainsizeswereformedfromtopsurfacetodeepmatrixwhichofferedagreatopportunitytostudytherefinementprocessoftheferritegrains.Itisfoundthatdislocationactivitiesplayadominantroleintheprocess.Attheinitiatestage,dislocationsaccumulatedandinteractedtoformdensedislocationwallsandcells.Increasingstrainandstrainrateinducedmoredislocationwallsincells,formingfinercells.Thisprocedurecontinueduntilnanograinsformedatthetopmostsurface.Theexistenceofcementiteparticlesinferritematrixgreatlyfacilitatestheferriterefinementprocess.Boundariesbetweenferritesandcementitesofferedmanydislocationsourceswhichacceleratethepropagationofdislocations.Dislocationwallswereblockedbycementiteswhichcertainlyleadtofinerdislocationcells.Theexistenceofcementitesmakesiteasiertogeneratefreshdislocationwallsinsub-microngrains.Astraingradientwasformedfromacementiteparticletosurroundingferritegrains.Thisstraingradientgivesrisetomoregeometricnecessarydislocations.Asferritegrainsizedecreasedlessthanthatofcementiteparticles,fragmentationoccurredincementites.Hardsecondphasewasusuallyconsideredasbrittle.Inthiswork,evidencesofdeformation(tracesofdislocationactivities)incementitesweredistinct.Sincethestressconcentrationinthephaseboundary(espec

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  • 简介:Avariationaldataassimilationmethodisproposedtoestimatethenear-surfacesoilmoistureandsurfacesensibleandlatentheatfluxes.Themethodmergesthefivepartsintoacostfunction,i.e.,thedifferencesofwind,potentialtemperature,antispecifichumiditygradientbetweenobservationsandthosecomputedbytheprofilemethod,thedifferenceoflatentheatfluxescalculatedusingtheECMWFlandsurfaceevaporationschemeandtheprofilemethod,andaweakconstraintforsurfaceenergybalance.Byusinganoptimalalgorithm,thebestsolutionsarefound.ThemethodistestedwiththedatacollectedatFeixiStation(31.41°N,117.08°E)supportedbytheChinaHeavyRainExperimentandStudy(HeRES)during7-30June2001.Theresultsshowthatestimatednear-surfacesoilmoisturescanquicklyrespondtorainfall,andtheirtemporalvariationisconsistentwiththatofmeasurementsofaveragesoilmoistureover15-cmtopdepthwithamaximumerrorlessthan0.03m~3m~(-3).ThesurfaceheatfluxescalculatedbythismethodareconsistentwiththosebytheBowenratiomethod,butatthesametimeitcanovercometheinstabilityproblemoccurringintheBowenratiomethodwhenthelatterisabout-1.Meanwhile,thevariationalmethodismoreaccuratethantheprofilemethodintermsofsatisfyingthesurfaceenergybalance.Thesensitivitytestsalsoshowthatthevariationalmethodisthemoststableoneamongthethreemethods.

  • 标签: 土壤湿度 热能量 可变模型
  • 简介:LOCALINTERPOLATINGBLENDEDB-SPLINESURFACEANDITSCONVERSIONTOTHENURBSSURFACEWangLazhu;ZhuXinxiongLOCALINTERPOLATINGBLENDEDB-SPLI...

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  • 简介:Understandingthetransformationofliquidsteeltosolidsteelisthemostfundamentalaspectofcontinuouscasting;however,itremainsacomplexsubjectwithanumberofunresolvedissues.Inthispaper,thefollowingaspectsofmoldoperationwhichgiverisetosub-surfacedefectswillbediscussed;meniscussolidification,surfaceandinterfacialenergies,effectsofgasbubbles,andthedynamicnatureoftheliquidslag-liquidsteelinterface.

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  • 简介:Aporosity-freeandcontamination-freesurfacelayerwithgrainsizesrangingfromnanometertomicrometerinFesampleswasobtainedbysurfacemechanicalattritiontreatment(SMAT)technique.MechanicalandwearpropertiesofthesurfacelayerintheSMATedandannealedFesamplesweremeasuredbymeansofnanoindentationandnanoscratchtests,respectively.ExperimentalresultsshowedthatthehardnessofthesurfacelayerintheSMATedFesampleincreasedevidentlyduetothegrainrefinement.TheelasticnoduliofthesurfacelayersintheSMATedandannealedFesampleswereunchanged,independentofgrainsizeinthepresentgrainsizeregime.ComparedwiththeoriginalFesample,thewearresistanceenhancedandthecoefficientoffrictiondecreasedinthesurfacelayeroftheSMATedFesample.

  • 标签: 机械性能 耐磨损性能 纳米晶体材料
  • 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:闪锌矿(110)的电子性质出现忍受Fe,Mn和Cd杂质在闪锌矿的铜激活上用杂质的密度功能的理论,和效果被计算被调查。计算结果显示Fe和Mn杂质缩小闪锌矿表面的乐队差距并且导致变到传导乐队的费密水平。由Fe3d和Mn3d组成的杂质层次在乐队差距的轨道的出现对从原子价乐队的电子转移有益到传导乐队并且支持表面电导率和电气化学的活动。Fe和Mn杂质不能被Cu原子代替的结果表演,它为Cu原子,因此忍受Fe和忍受Mn闪锌矿减少交换地点(Zn)是难的被铜激活。Cd杂质在闪锌矿表面的电子结构上有小效果;然而,Cd原子被Cu原子容易代替,并且这是忍受Cd闪锌矿能容易被漂浮的原因。

  • 标签: 表面活化 闪锌矿 铜原子 晶格缺陷 表面性能 量子力学