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: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:Wereportedacoaxial,micro-dielectricbarrierdischarge(micro-DBD)reactorandaconventionalDBDreactorforthedirectconversionofmethaneintohigherhydrocarbonsatatmosphericpressure.Theeffectsofinputpower,residencetime,dischargegapandexternalelectrodelengthwereinvestigatedformethaneconversionandproductselectivity.Wefoundtheconversionofmethaneinamicro-DBDreactorwashigherthanthatinaconventionalDBDreactor.Andataninputpowerof25.0W,theconversionofmethaneandthetotalC2+C3selectivityreached25.10%and80.27%,respectively,withamicro-DBDreactorof0.4mmdischargegap.Finally,anonlinearmultipleregressionmodelwasusedtostudythecorrelationsbetweenbothmethaneconversionandproductselectivityandvarioussystemvariables.ThecalculateddatawereobtainedusingSPSS12.0software.Theregressionanalysisillustratedthecorrelationsbetweensystemvariablesandbothmethaneconversionandproductselectivity.
简介:Theanalysisofstableisotopesofcarbonandoxygenindifferentcarbonaterocksbythephosphoricacidmethodisnoteasierthanthatbythelasersamplingmethoddevelopedinrecentyears,whichopticallyfocuseslaserbeamswithsufficientenergyonamicroareaofathinsectioninavacuumsampleboxviamicroscope.CO2producedbyheatingdecompositionofcarbonatewaspurifiedbythevacuumsystem,andthestableisotopicvaluesofcarbonandoxygenwerecalculatedandanalyzedonamassspectrometer.Thispaperadoptedthelasermicro-samplingtechniquetoanalyzethestableisotopesofcarbonandoxygenindolomite,carbonatecement,stromatoliteanddifferentformsofdawsonite(donbassite).Resultsindicatedthatthelasermicro-samplingmethodiseffectiveinanalyzingcarbonatecompositionandcouldbeaconvincingproofforjustificationoncarbonatecompositionanalysis.
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:Micro-poredCA6-MAlightweightmaterialwithCA6:MAmassratioof7:3waspreparedusingAl(OH)3.MgCO3andCaCO3asstartingmaterials,andanthracite.sweetpotatostarchandanthracite+sweetpotatostarchasporeformingagent(PFA)withanadditionof10mass%.20mass%and30mass%.respectively.Thestartingmaterialsweredrymixed.wetco-milledinaballmillfor1h.slipcastintocylindricalspecimenswithadiameterof60mm.andthencalcinedat1450℃for3h.WiththeincreaseofPFAaddition.apparentporosityincreases,andbulkdensitydecreases.TheinfluenceofdifferentPFAsonpropertiesofthemicro-poredLWCA6-MAaggregatewasinvestigated.TheachievedCA6-MA.byadding30%sweetpotatostarch.hasaporosityof76.8%.bulkdensityof0.78g·cm-3andmedianporesizeof1.90μm.
简介:Inthisstudy,wedevelopedageneralmethodtoanalyticallytackleakindofmovableboundaryproblemfromtheviewpointofenergyvariation.Havinggroupedtheadhesionofamicro-beam,dropletandcarbonnanotube(CNT)ringonasubstrateintooneframework,weusedthedevelopedlineofreasoningtoinvestigatetheadhesionbehaviorsofthesesystems.Baseduponthederivedgoverningequationsandtransversalityconditions,explicitsolutionsinvolvingthecriticalparametersandmorphologiesforthethreesystemsaresuccessfullyobtained,andthentheparameteranalogiesandcommoncharacteristicsofthemarethoroughlyinvestigated.Thepresentedmethodhasbeenverifiedviatheconceptofenergyreleaserateinfracturemechanics.Ouranalysesprovideanewapproachforexploringthemechanismofdifferentsystemswithsimilaritiesaswellasforunderstandingtheunityofnature.Theanalysisresultsmaybebeneficialforthedesignofnano-structuredmaterials,andholdpotentialforenhancingtheirmechanical,chemical,opticalandelectronicproperties.
简介:Micro-arcoxidation(MAO)processwascarriedoutinanoptimizeddualelectrolytesystemtofabricateacompact,smooth,andcorrosionresistantcoatingonZK60Mgalloy.Themicrostructuralcharacteristicsofcoatingwereinvestigatedbyscanningelectronmicroscopy(SEM)coupledwithanenergydispersivespectrometer(EDS)andX-raydiffraction(XRD).Testofmasslosswasconductedata3.5%NaClsolutiontoassesstheresistancetocorrosion.ThebondingstrengthbetweenthecoatingandZK60substratewasevaluatedusingscratchexperiment.TheresultsrevealthatMgAl2O4andMgOarethemainphasesofceramiccoatingobtainedinthedualelectrolytesystem.Thecorrosionrateofcoatingpreparedintheoptimizeddualelectrolyteisonly0.0061gám-2áh-1,whichdemonstratesexcellentcorrosionresistance.Thisismainlyduetothecompact,uniformcoatingwithhighbondingstrength.
简介:Sulphonatednano-structuredmicro-porousionexchangepolymers,knownassulphonatedPolyHIPEPolymers(s-PHPs)wereusedinsyngascleaningtoinvestigatetheirimpactontarcomposition,concentrationanddewpointdepressionduringthegasificationoffuelcanebagasseasamodelbiomass.Theresultsshowedthatthes-PHPsusedasasecondarysyngastreatmentsystem,washighlyeffectiveatadsorbingandreducingtheconcentrationofallclassoftarsinsyngasby95%-80%whichresultedintardewpointdepressionfrom90℃to73℃.Itwasshownthattarsunderwentchemicalreactionswithins-PHPs,indicatingthattardiffusionfromsyngaswasdrivenbychemicalpotential.Itwasalsoobservedthats-PHPsalsocapturedashformingelementsfromsyngas.Theuseofs-PHPsingasificationaswellasinanintegratedthermochemicalbiorefinerytechnologyisdiscussedsincethetarloadeds-PHPscanbeusedasnaturalherbicidesintheformofsoiladditivestoenhancethebiomassgrowthandcropyield.
简介:摘要目的观察60µɡ重组乙型肝炎疫苗(酵母)用于无应答人群的免疫成功率和免疫效果。方法将经常规剂量和程序接种3剂乙肝疫苗后,查血无乙肝表面抗体产生的无应答人群病例130例,分成观察组和对照组各65例。观察组应用深圳泰康生物制品有限公司生产的60µɡ重组乙型肝炎疫苗(酵母)采用一针接种;对照组再次按常规剂量和程序接种3剂乙肝疫苗,观察两组免疫效果和不良反应。结果观察组抗体阳转率(90.77%),明显高于对照组(63.08%),两组均未发生严重不良反应。结论60µɡ重组乙型肝炎疫苗(酵母)安全性良好,免疫成功率高,对于常规免疫无应答人群的免疫效果更好。