简介:Anovelfabricationprocessformicropatternswithcurvaturewasintroduced.Thecurvedstructuresweremadebycompensatingrectangularmicrostructureswithliquidphotoresistlayer.Becauseofthesurfacetensionoftheliquidinmicroscale,variousshapesofmeniscuscanbemadeonthemicrochannels.Themicrochannelsweremadeonthesiliconsubstrateinadvance,andthentheliquidlayerwascoatedonthemicrochannels.Fromthenatureofliquidbehavior,thecurvedpatternswithsmoothsurfaceareobtained,whichcannotbemadeeasilywiththeconventionalmechanicalmachining,aswellaswiththemicrofabricationprocesses,suchaswetanddryetching.Withthisprinciple,itisexpectedthatthesmoothandcurvedsurfacescanbemadebysimpleprocessesandtheresultscanbeappliedwidely,suchasopticalpatterns.
简介:WereportamonolithicTm:YLFmicrolaserinthisLetter.Inordertoimprovetherelaxationoscillationofthelaser,bothendsofthecrystalarecoated,makingtheTm:YLFcrystalitselfaresonantcavity.Themicrolaserispumpedbya792nmlaserdiodeoperatedinthecontinuouswave(CW)mode.Weobtainmaximumoutputpowersof7.78and10.4Watthetotalincidentpowerof43.6Wwithfocuslensesof37.5and40mm,respectively,correspondingtotheslopeefficienciesof25.6%and40.0%andtheoptical–opticalconversionefficienciesof17.8%and23.8%.Itisclearthattheamplitudeoftherelaxationoscillationissmallerandthebeamqualityisbetterwiththefocuslengthof37.5mm;however,thelaserwiththefocuslengthof40mmproducesahigheroutputpowerandamorestablewavelengthcenteringat1878.44nm.
简介:WhatisacredibleseismicprecursorinobservationofdeformationArealseismicprecursoroughttoberesultedfromthevariationsintheearthstrainandstress.Thedeformationobservationcanprovidetheinformationduringearthquakegestationandoccurrenceperiodforus.Usuallytheseismicprecursorscanbedividedintofieldandepicentralregionprecursors.Theprecursorinformationisveryusefulforseismicpredictionfromepicentralregionornearepicentralregion.Micro-deformationobservationmainlyincludestilt,strainandgravityobservation.ComparedwithGPS,geodesyandmobiledeformationobservation,micro-deformation(tilt,strain)showsthechangeofdeformationwhichiscontinualinalimitedvolumewithdominantobservedrangeof10(6~10(10m.Becausethevariationofthecrustalnatureandcrackingcanbedirectlyobtainedbymicro-deformationobservation,itisaneffectivewaytofindmiddle-shorttermandshort-termprecursor.
简介:Inthisstudy,micro-hollowcathodedischarge(MHCD)isinvestigatedbyafluidmodelwithdrift-diffusionapproximation.TheMHCdeviceisacathode/dielectric/anodesandwichstructurewithoneholeofadiameterD=200μm.ThegasisaNe/Xemixtureatapressurep=50~500Torr.Theevolutionsofthedischargeshowthattherearetwodifferentdischargemodes.AtlargerpDthedischargeplasmaandhighdensityexcitedspeciesexpandalongthecathodesurfaceand,aringeddischargemodeisformed.AtsmallerpD,thedischargeplasmaandtheexcitedspeciesexpandalongtheaxisofthecathodeaperturetoformacolumnardischarge.
简介:Thispaperdescribestheuseofoverlappinggridsforthecalculationofflowaroundsingleandmultiple-particleconfigurationsatthemicroscale.ThebasicequationsforcalculationarethoseforconservationofmassandmomentumwhicharesolvedusingacommonFinite-Volumeformulation.Thehydrodynamicparticle-particleandparticle-wallinteractioncanbecalculatedbyusinganoverlappingorChimeragridscheme.Withthegridstructuringprocedureitispossibletousesimpleandstructuredgridsaroundtheparticlesandtheoverallmaingridgeometry.Theparticlegridsarelappedoverthemaingridsuchthattheycanmoveindependentlyaftereachtimestepwithoutremeshingthewholegeometry.Thepapergivesresultsforthevalidationofthecodedevelopedforgeneraltestcases,forarotatingellipsoidinsimpleshearflow,theflowaroundparticlesattachedtoawall,themotionofaparticleinthevicinityofawallandsomeresultsfortheflowthroughapackedbedconfiguration.
简介:Inthispaper,wepresentahighspeedautofocussystemformicrosystemapplicationsanddesignalook-up-tablebasedautofocusingalgorithmforapplicationswhenatargetobjectisalwaysvisible,e.g.,manufacturingpartswithalignmentfiducials.Weperformanevaluationof24focusmeasurestoverifythatwhichfocusmeasureisthebestforthelook-up-tablebasedmethod.Fromtheevaluation,wefindthattheChebyshevmoments-basedfocusmeasure(CHEB)isthemostsuitable.Furthermore,wealsodevelopalook-up-tablebasedautofocussystemthatusesCHEBasthefocusmeasure.Intrainingphase,weofflineconstructatablefromtrainingimagesofanobjectthatarecapturedatseverallensdistances.Eachentryoftableconsistsoffocusmeasurecomputedfromimageandlensdistance.Inworkingphase,givenaninputimage,thealgorithmfirstcomputesthefocusmeasureandthenfindsthebestmatchfocusmeasurefromthetableandlooksupthecorrespondinglenspositionformovingitintothein-focusposition.Ouralgorithmcanperformautofocusingwithinonly2stepsoflensmoving.Theexperimentshowsthatthesystemcanperformhighspeedautofocusingofmicroobjects.
简介:Anoveldischargedeviceisdesignedonthebasisoftheconfigurationofmicro-hollowcathodedischarge(MHCD).ByusingmanyMHCDsinparallelconnection,amicro-dischargearraycanbeconstructed.Withthemicro-dischargearray,ahigh-pressurehigh-currentdensityglowdischargeplasmascanbeformedtomakeaplasmadisplaypanel(PDP).Anairdischargeexperimentisfinishedwiththedischargedevice.Thestabledirectcurrentglowdischargeisformedunderthepressurefrom20Torrto500Torr.Thevoltage-currentcharacteristiccurveandthedischargephotographarenoted.Thevoltage-currentcharacteristiccurvehasapositivedifferentialresistancecoefficientonthewholedischargerange.Theestimatedcurrentdensityreaches70.1A/cm3,thepowerdensityis3.6×104W/cm3,andtheelectrondensityisintheorderof1013cm-3atp=200TorrandID=10mA.TheexperimentalresultsindicatethatthedesigneddischargedeviceisappropriateforPDP.
简介:JiaXiangdejustdidn’tknowwhattodowhen,fiveyearsago,helosthisjobatastate-ownedchemicalfactory.Hewasgivenmi"unemploymentpay"of200yuan(US$24.1)permonthforhisfamilyofseven."Mywilehadnojobandlifewasreallyhardforus,"herecalls."IhadthoughtIwouldbedoneforuntilthegovernmentsteppedintohelp.Igotapettyloanfromthegovernment,andthathashelpedmeturnanewleafinlife."
简介:TheRamanspectrafromleukemiccellline(HL60)andnormalhumanperipheralbloodmononuclearceils(PBMCs)areobtainedbyconfocalmicro-Ramanspectroscopyusingnear-infraredlaser(785nm)excitation.Thescanningrangeisfrom500to2000cm-1.ThetwoaverageRamanspectraofnormalPBMCsandcarcinomacellshavecleardifferencesbecausetheirstructureandamountofnucleicacid,protein,andothermajormoleculesarechanged.Thespectraarealsocomparedandanalyzedbyprincipalcomponentanalysis(PCA)todemonstratethetwodistinctclustersofnormalandtransformedcells.Thesensitivityofthistechniqueforidentifyingtransformedcellsis100%.更多还原
简介:Micro-retailenterprises(MREs)havehadtoadapttochangingconditionsinregardstomobilepayments(m-payments)andaccesstoloans.TheauthorsbuiltonthepublishedresultsoftwoprevioussurveysofMREs.Onethousandninehundredandninety-eightMREsinfourcitiesinChinaweresurveyedinMayandJuneof2018todeterminetheuseandimportanceofm-paymentstotheirbusiness,theiraccesstoloans,andpatternsofentrepreneurship.Whilesometrendsremainunchanged,atleasttwosignificantfindingsemerge.M-paymentshavenotonlygainedalmostuniversalacceptancebyMREsinChina;theyaretheoverwhelminglypreferredpaymentmethod.Inourlastpaper,wearguedthat“m-paymentsmayrepresentaformofleapfroggingtechnologywhichwillspurgrowthinthissector”andthispaperprovidesadditionalevidencethisisoccurring.M-paymentsshoweverysignofbeinganexampleofaleapfroggingtechnologythatisquicklychangingtherulesforretailintheMREsectorandopeningnewopportunitiesforbusinesseswhileloweringtransactioncosts,reducingfraud,andimprovingcustomersatisfaction.Thereareintriguingimplications,includingchangestothepaceofm-paymentsreplacingcreditcards.Second,whileitremainstruethatoverall,accesstoloansforMREsislimited;thereisagreatdealofvariationbetweentier-onecitiesandtier-twoandtier-threecities.
简介:Anexperimentalstudywascarriedouttoinvestigatetheinfluenceofdoubletwisted-tapeinserts(DTs)inmicro-fintubes(MFs)onheattransfer,frictionfactorandthermalperformancefactorcharacteristicsofthecompounddevicesinthefollowingconfigurations:(1)twistedtapesactedinthesamedirection(forco-swirl)whileMFandtwistedtapesactedinthesame(parallel)direction(MF-CoDTs:P),(2)twistedtapesactedinthesamedirection(forco-swirl)whilemicro-fintubeandtwistedtapesactedinoppositedirections(MF-CoDTs:O)and(3)twistedtapesactedinoppositedirectionsforcounterswirl(MF-CDTs).TheMFaloneandtheMFequippedwithasingletwistedtapeinparallel/oppositearrangementwerealsoconsideredforcomparison.TheexperimentswereconductedfortheflowswiththeReynoldsnumbersbetween5650and17000,underuniformheatfluxcondition.TheexperimentalresultsindicatethatMF-CDTsinducestrongerswirl/turbulenceflow,resultinginhigherheattransferrate,frictionfactorandthermalperformancefactorthanothercombineddevices.ThethermalperformancefactorsassociatedwiththeuseofMF-CDTswerefoundtobehigherthanthoseassociatedwiththeusesofMF-CoDTs:P,MF-CoDTs:OandMFaloneupto9.3%,6.5%and56.4%,respectively.TheempiricalcorrelationsdevelopedusingthepresentexperimentaldatafortheNusseltnumber,frictionfactorandthermalperformancefactorarealsoreported.
简介:Naturalsurfaceswithsuperhydrophobicpropertiesoftenhavemicroorhierarchicalstructures.Inthispaper,thewettingbehavioursofasingledropletonbiomimeticmicrostructuredsurfaceswithdifferentroughnessparametersareinvestigated.Atheoreticalmodelisproposedtostudywettingtransitions.Theresultsoftheoreticalanalysisarecomparedwiththoseofexperimentindicatingthattheproposedmodelcaneffectivelypredictthewettingtransition.Furthermore,anumericalsimulationbasedonthemesoscaleLatticeBoltzmannMethod(LBM)isperformedtostudydynamiccontactangles,contactlines,andlocalvelocityfieldsforthecasethatadropletdisplaysonthemicrostructuredsurface.Asphericalwaterdropletwithrs=15μmfallsdowntoabiomimeticsquare-postpatternedsurfaceundertheforceofgravitywithaninitialvelocityof0.01m·s-1andaninitialverticaldistanceof20μmfromdropletcentretothetopofpots.Inspiteofahigherinitialvelocity,thedropletcanstillstayinaCassiestate;moreover,itreachesanequilibriumstateatt≈17.5ms,whencontactangleis153.16°whichisslightlylowerthanthepredictionofCassie-Baxter’sequationwhichgivesθCB=154.40°.
简介:Dopedmicro-crystallinesiliconfilmsaredepositedattemperaturesaslowas400℃bythecatalyticchemicalvapordepositionmethodusingasilaneandhydrogengasmixture.ElectricalpropertiessuchasthecarrierconcentrationandtheHallmobilityareinvestigatedforvariousmeasuringtemperatures.Itisfoundthatthegrainsofmicro-crystallinesiliconarepreferentiallyorientedalongthe(220)direction,andthattheHallmobilityislargerthan8cm^2·V^-1·s^-1,thecarrierconcentrationisabout1×10^17cm^-1-1×10^19cm^-3atroomtemperature.