简介：Thispaperdescribestheuseofoverlappinggridsforthecalculationofflowaroundsingleandmultiple-particleconfigurationsatthemicroscale.ThebasicequationsforcalculationarethoseforconservationofmassandmomentumwhicharesolvedusingacommonFinite-Volumeformulation.Thehydrodynamicparticle-particleandparticle-wallinteractioncanbecalculatedbyusinganoverlappingorChimeragridscheme.Withthegridstructuringprocedureitispossibletousesimpleandstructuredgridsaroundtheparticlesandtheoverallmaingridgeometry.Theparticlegridsarelappedoverthemaingridsuchthattheycanmoveindependentlyaftereachtimestepwithoutremeshingthewholegeometry.Thepapergivesresultsforthevalidationofthecodedevelopedforgeneraltestcases,forarotatingellipsoidinsimpleshearflow,theflowaroundparticlesattachedtoawall,themotionofaparticleinthevicinityofawallandsomeresultsfortheflowthroughapackedbedconfiguration.

简介：U-shapedmicro-nanochannelscangeneratesignificantflowdisturbanceaswellaslocallyamplifiedelectricfield,whichgivesitselfpotentialtobemicrofluidicmixers,electrokineticpumps,andevencelllysisprocess.NumericalsimulationisutilizedinthisworktostudythehiddencharacteristicsoftheU-shapedmicro-nanochannelsystem,andtheeffectsofkeycontrollingparameters(theexternalvoltageandpressure)onthedeviceoutputmetrics(current,maximumvaluesofelectricfield,shearstressandflowvelocity)wereevaluated.Alargeportionofcurrentflowingthroughthewholesystemgoesthroughthenanochannels,ratherthanthemiddlepartofthemicrochannel,withitsvalueincreasinglinearlywiththeincreaseofvoltage.Duetothelocaliondepletionnearmicro-nanofluidicjunction,significantlyenhancedelectricfield(asmuchas15foldatV=1VandP0=0)aswellasstrongshearstress(leadingtoelectrokineticflow)isgenerated.Withincreasingexternalpressure,bothelectricfieldandshearstresscanbeincreasedinitially(duetoshorteningofdepletionregionlength),butaresuppressedeventuallyathigherpressureduetothedestructionofiondepletionlayer.Insightsgainedfromthisstudycouldbeusefulfordesigningnonlinearelectrokineticpumpsandothersystems.

简介：Fabricationofmicrogratingsusingafemtosecondlaserexposuresystemisexperimentallyinvestigatedfortheelectronmoirémethod.Microholesandlinesarefirstlyetchedforparameterstudy.Gratingprofileistheoreticallyoptimizedtoformhighqualitymoirépatterns.Forademonstration,aparallelgratingisfabricatedonaspecimenofquartzglass.Theminimumlinewidthandthedistancebetweentwoadjacentlinesarebothsettobe1μm,andthefrequencyofgratingis500lines/mm.Theexperimentalresultsindicatethatthequalityofgratingsisgoodandtherelativeerrorofthegratingspitchisabout1.5%.Basedonmoirémethod,scanningelectronmicroscope(SEM)moirépatternsareobservedclearly,whichmanifeststhatgratingsfabricatedwiththefemtosecondlaserexposureissuitableformicroscaledeformationmeasurement.

简介：Transmissionofelasticwavesthroughamicrogapbetweentwosolidswithconsiderationoffrictionalcontactisinvestigated.ByusingtheFourieranalysistechniqueandthecorrectivesolutionmethod,thenonlinearboundaryproblemisreducedtoasetofalgebraicequations.Numericalresultsexhibitthelocationsandextentsofseparation,slip,andstickzones,theinterfacetractions,andtheenergypartition.Theeffectsofgapwidth,frictionalcoefficients,andtheincidentangleonthewavetransmissionarediscussedindetail.Theresultsshowthathigherharmonicsaregeneratedduetothelocalcontact/slipattheinterface.

简介：Smallconcentrationsofahigh-molecular-weightpolymerhavebeenusedtocreateso-called'elasticturbulence'inamicro-scaleserpentinechannelgeometry.Itisknownthattheinteractionoflargeelasticstressescreatedbytheshearingmotionwithinthefluidflowwithstreamlinecurvatureoftheserpentinegeometryleadsinitiallytoapurely-elasticinstabilityandthenthegenerationofelasticturbulence.Weshowthatthiselasticturbulenceenhancestheheattransferatthemicro-scaleinthisgeometrybyupto300%undercreepingflowconditionsincomparisontothatachievedbytheequivalentNewtonianfluidflow.

简介：Wingfappingandmorphingcanbeverybenefcialtomanagingtheweightofmicroairvehiclesthroughcouplingtheaerodynamicforceswithstabilityandcontrol.Inthisletter,harvestingenergyfromthewingmorphingisstudiedtopowercameras,sensors,orcommunicationdevicesofmicroairvehiclesandtoaidinthemanagementoftheirpower.Theaerodynamicloadsonfappingwingsaresimulatedusingathree-dimensionalunsteadyvortexlatticemethod.Activewingshapemorphingisconsideredtoenhancetheperformanceofthefappingmotion.Agradient-basedoptimizationalgorithmisusedtopinpointtheoptimalkinematicsmaximizingthepropellentefciency.Tobeneftfromthewingdeformation,weplacepiezoelectriclayersnearthewingroots.Gausslawisusedtoestimatetheelectricalharvestedpower.Wedemonstratethatenoughpowercanbegeneratedtooperateacamera.Numericalanalysisshowsthefeasibilityofexploitingwingmorphingtoharvestenergyandimprovingthedesignandperformanceofmicroairvehicles.

简介：Indentationisasimpleandnondestructivemethodtomeasurethemechanicalpropertiesofsoftmaterials,suchashydrogels,elastomersandsofttissues.Inthiswork,wehavedevelopedamicro-indentationsystemwithhigh-precisiontomeasurethemechanicalpropertiesofsoftmaterials,wheretheshearmodulusandPoisson’sratioofthematerialscanbeobtainedbyanalyzingtheload–relaxationcurve.Wehavevalidatedtheaccuracyandstabilityofthesystembycomparingthemeasuredmechanicalpropertiesofapolyethyleneglycolsamplewiththatobtainedfromacommercialinstrument.Themechanicalpropertiesofanothertypicalpolydimethylsiloxanesamplesubmergedinheptanearemeasuredbyusingconicalandsphericalindenters,respectively.ThemeasuredvaluesofshearmodulusandPoisson’sratioarewithinareasonablerange.

简介：Inthispaper,weproposeaninstantaneousphase-steppingmethodfordeterminingphasedistributionofinterferencefringesutilizingacamerathatisequippedwithamicro-polarizerarrayonthesensorplane.AnopticalsetupofpolarizationinterferometryusingaMach–Zehnderinterferometerwithtwopolarizersisconstructed.Lightemergingfromtheinterferometerisrecordedusingacamerathathasamicro-polarizerarray.Thismicro-polarizerarrayhasfourdifferentopticalaxes.Thatis,animageobtainedbythecameracontainsfourtypesofinformationcorrespondingtofourdifferentopticalaxesofthepolarizer.Thefourimagesseparatedfromtheimagerecordedbythecameraarereconstructedusinggraylevelinterpolation.Subsequently,thedistributionsoftheStokesparametersthatrepresentthestateofpolarizationarecalculatedfromthefourimages.ThephasedistributionoftheinterferencefringepatternproducedbytheMach–ZehnderinterferometeristhenobtainedfromtheseStokesparameters.Theeffectivenessoftheproposedmethodisdemonstratedbymeasuringastaticcarrierpatternandtime-variantfringepatterns.Itisemphasizedthatthismethodisapplicabletotime-variantphenomenabecausemultipleexposuresareunnecessaryforsufficientdataacquisitioninthecompletionofthephaseanalysis.

简介：Liquidmicro-jets,producedfromgasdynamicvirtualnozzles(GDVNs),areusedassamplecarriersforinteractionwithX-raybeaminserialfemtosecondcrystallography(SFX).Anumericalinvestigationoftheeffectofthefocusinggastypeontheliquidmicro-jetproperties(itslengthandthickness)ispresented.ThestudycomplementsourpreviousresearchontheinfluenceofoperatingconditionsandthenozzlegeometryonGDVNperformance.Theinfluenceofhelium,argon,carbondioxideandnitrogengases(atafixedmassflowrateof1.6×104mg/min)onfocusingpurewaterjet(flowrateof33μl/min)isanalysed.

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简介：基于Si的多层的结构广泛地在当前的微电子学被使用。在他们的准备期间，一些不同类的剩余应力被导致，导致在接口错配和表面精力和平导致结构失败之间的竞争。这个工作在多层的半导体heterostructure在剩余应力的测量上介绍方法学的研究。扫描电子显微镜学(SEM)，micro-Raman光谱学(太太)，和传播电子显微镜学(TEM)被使用测量多层的结构的几何参数。在拉曼光谱和压力/紧张在上之间的关系[100]并且[110]水晶取向被决定分别地启用表面和剖面图剩余压力分析。基于印射结果的拉曼，沿着多层的heterostructure的深度的剩余应力的分发成功地被获得。

简介：Inthispaper,aclustermodelinparticleflowcodewasusedtosimulategranitespecimensafterheattreatmentunderuniaxialcompression.Theresultsdemonstratedthatmicro-cracksarerandomlydistributedinthespecimenwhenthetemperatureisbelow300?C,andhavepartialcoalescencewhenthetemperatureisupto450?C,thenformmacro-crackswhenthetemperatureisabove600?C.Thereismoreinter-granularcrackingthanintra-granularcracking,andtheirratioincreaseswithincreasingtemperature.Themicro-cracksarealmostconstantwhenthetemperaturedecreasesfrom900?Ctoroomtemperature,exceptforquartzα–βphasetransitiontemperature(573?C).Thefractureevolutionprocessisobviouslyaffectedbythesecracks,especiallyat600–900?C.Elevatedtemperatureleadstoeasilydevelopeddisplacementbetweenthegrains,andthecapacitytostorestrainenergybecomesweaker,correspondingtotheplasticityofgraniteafterheattreatment.

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简介：Thenonlineardynamicandstaticdeflectionofamicro/nanogyroscopeunderDCvoltagesandbaserotationareinvestigated.Thegyroscopeundertakestwocoupledbendingmotionsalongthedriveandsensedirectionsandsubjectedtoelectrostaticactuationsandintermolecularforces.Thenonlineargoverningequationsofmotionforthesystemwiththee?ectofelectrostaticforce,intermoleculartractionsandbaserotationarederivedusingextendedHamiltonprinciple.Underconstantvoltage,thegyroscopefindsthepreformedshape.First,thedeflectionofthemicro/nanogyroscopeunderelectrostaticforcesisobtainedbystaticanddynamicanalyses.Furthermore,thestaticanddynamicinstabilityofthesystemareinvestigated.Afterwardtheoscillatorybehaviorofthepre-deformedmicro/nanogyroscopearoundequilibriumisstudied.Thee?ectsofintermolecularandnonlinearparametersonthestaticanddynamicdeflection,naturalfrequenciesandinstabilityofthemicro/nanogyroscopearestudied.Thepresentedmodelcanbeusedtoexactlydeterminestaticandthedynamicbehaviorofvibratorymicro/nanogyroscopes.

简介：Inthisstudy,wedevelopedageneralmethodtoanalyticallytackleakindofmovableboundaryproblemfromtheviewpointofenergyvariation.Havinggroupedtheadhesionofamicro-beam,dropletandcarbonnanotube(CNT)ringonasubstrateintooneframework,weusedthedevelopedlineofreasoningtoinvestigatetheadhesionbehaviorsofthesesystems.Baseduponthederivedgoverningequationsandtransversalityconditions,explicitsolutionsinvolvingthecriticalparametersandmorphologiesforthethreesystemsaresuccessfullyobtained,andthentheparameteranalogiesandcommoncharacteristicsofthemarethoroughlyinvestigated.Thepresentedmethodhasbeenverifiedviatheconceptofenergyreleaserateinfracturemechanics.Ouranalysesprovideanewapproachforexploringthemechanismofdifferentsystemswithsimilaritiesaswellasforunderstandingtheunityofnature.Theanalysisresultsmaybebeneficialforthedesignofnano-structuredmaterials,andholdpotentialforenhancingtheirmechanical,chemical,opticalandelectronicproperties.

简介：Numerousexperimentalevidencesshowthatthegrainsizemaysignificantlyaltertheyieldstrengthofmetals.Similarly,in-strengthenednickel-basedsuperalloys,theprecipitatesizealsoinfluencestheiryieldstrength.Then,howtodescribesuchtwokindsofsizeeffectsontheyieldstrengthisaverypracticalchallenge.Inthisstudy,accordingtoexperimentalobservations,acollinearmicro-shear-bandsmodelisproposedtoexplorethesesizeeffectsonmetalmaterials’yieldstrength.Ananalyticalsolutionforthesimplemodelisderived.Itrevealsthattheyieldstrengthisafunctionofaveragegrain-sizeorprecipitate-size,whichisabletoreasonablyexplainsizeeffectsonyieldstrength.Thetypicalexamplevalidationshowsthatthenewrelationshipisnotonlyabletopreciselydescribethegrain-sizeeffectinsomecases,butalsoabletotheoreticallyaddresstheunexplainedHall-Petchrelationshipbetweentheγprecipitatesizeandtheyieldstrengthofnickel-basedsuperalloys.

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简介：锁泉华的microfibrous网络由8m(dia)的3vol.%组成镍microfibers被利用了骗诱100200mdia的30vol.%。多孔的Al2O3。ZnO和CaO然后被早期的湿受精方法高度驱散到骗诱的Al2O3的毛孔表面上。由于表面区域，毛孔尺寸/粒子尺寸，热传导性，和空体积的唯一的联合，当在甲醇蒸气改过使用了时，产生microfibrous催化剂composites提供了催化的床反应和利用效率的重要改进。粗略地甲酸盐的260mL/min，包括>70%H2，<5%公司和踪迹CH4，与>97%甲醇变换，能在我们骗诱的新奇microfibrous的1cm3床卷被生产在470湩瑡潩?潰祬敭r合成的ZnO-CaO/Al2O3催化剂?鑈я鑈я8

简介：Anoveltwo-stagereductionprocessforsynthesisofultrafinenickelpowderwithahighpurityandlowdensityinafluidizedbedreactorhasbeendevelopedinthiswork.TherawultrafineNiOparticlesarefirstpre-reducedusinghydrogenatlowertemperatures(340-400℃),followedbyfurtherreductionathighertemperatures(500-600℃).Theself-agglomerationofNiparticlesformedduringlow-temperaturereductiondecreasesthesinteringactivityofthenewlyformedultrafineNiparticles,leadingtogoodfluidizationquality,evenforthesubsequenthigh-temperaturereductionprocess.TheagglomeratedNiparticleshaveahighNicontent(above99wt%),alowdensity(0.78g/cm~3)andauniformparticlesize(approximately100μm).Aconceptdesignforanoveltwo-stagefluidizedbedreactorprocessusedtoproducehigh-purityNipowderwasalsoproposed.Thisapproachmaybeextendedtothesynthesisofotherultrafine/nanosizedmetalsormetaloxidesthroughafluidizationmethod.