简介:Wemeasuretheelectromagneticdegreeoftemporalcoherenceandtheassociatedcoherencetimeforquasi-monochromaticunpolarizedlightbeamsemittedbyanLED,afilteredhalogenlamp,andamultimodeHe–Nelaser.ThemethodisbasedonobservingattheoutputofaMichelsoninterferometerthevisibilities(contrasts)oftheintensityandpolarization-statemodulationsexpressedintermsoftheStokesparameters.Theresultsareingoodagreementwiththosededuceddirectlyfromthesourcespectra.Themeasurementsarerepeatedafterpassingthebeamsthroughalinearpolarizersoastoelucidatetheroleofpolarizationinelectromagneticcoherence.Whilethepolarizervariestheequal-timedegreeofcoherenceconsistentlywiththetheoreticalpredictionsandalterstheinnerstructureofthecoherencematrix,thecoherencetimeremainsalmostunchangedwhenthelightvariesfromunpolarizedtopolarized.Theresultsareimportantintheareasofapplicationsdealingwithphysicalopticsandelectromagneticinterference.
简介:Accurateaerodynamicmeasurementsinthehypersonicflowoflargeaircraftmodelsintunnelshavepracticalsignificance,butposeasignificantchallenge.Novelaerodynamicforcemeasurementmethodshavebeenproposed,butlacktheoreticalsupport.Theformsoftheforcesignalstechniquesforsignalprocessingandcalculationofaerodynamicsareespeciallyproblematic.Atheoreticalstudyisconductedtoinvestigatethedynamicpropertiesbasedonmodelsofthedraw-rodsystemandslenderrods.Theresultsindicatethattheinertiaitemcanbeneglectedintherodgoverningequation;further,thesolutionsshowthatthesignalsofeachrodareacombinationofaerodynamicsignals(withaconstantvalue)andsinesignals,whichcanbeverifiedbyexperimentalshocktunnelresults.Signalprocessingandaerodynamicscalculationtechniquesarealsofoundtobeachievableviatheflatpartofthesignals.
简介:ThespinHalleffectoflight(SHEL)canbeobservedbythedarkstripresultingfromweakmeasurement.WefindthattheSHELofapartiallycoherentbeam(PCB)hasasimilarphenomenonaswell.However,thedarkstripintheSHELofaPCBcannotbeexplainedbyconsideringthebeamasanassemblanceofcoherentspeckles.Also,thedarkstripinaPCBisnotpurelydark.Byanalyzingtheautocorrelation,weshowthattheSHELofaPCBistheresultofoverlappingcoherentspeckles'SHEL.Wefurtherproveourconclusionbyadjustingconvergenceandincidentangles.Finally,wedevelopaqualitativetheorytoclarifytheSHELofaPCB.
简介:Aliquidmodifiedphotoniccrystalfiber(PCF)integratedwithanembeddeddirectionalcouplerandmulti-modeinterferometerisfabricatedbyinfiltratingthreeadjacentairholesoftheinnermostlayerwithstandard1.48refractiveindexliquids.Therefractiveindexofthefilledliquidishigherthanthatofbackgroundsilica,whichcannotonlysupportthetransmittingrodmodesbutalsothe'liquidmodifiedcore'modespropagatingbetweenthePCFcoreandtheliquidrods.Hence,thelightpropagatingintheliquidmodifiedcorecanbeefficientlycoupledintothesatellitewaveguidesunderthephase-matchingconditions,resultinginadramaticdecreaseoftheresonantwavelengthintensity.Furthermore,thereisamulti-modeinterferenceproducedbymodifiedcoremodesandrodmodes.Suchacompact(~0.91cm)deviceintegratedwithanembeddedcouplerandinterferometerisdemonstratedforhigh-sensitivitysimultaneoustemperature(~14.72nm∕℃)andstrain(~13.01pm∕με)measurement.
简介:这份报纸为numberresolved主人方程的推导论述波浪功能途径的全面评论,在mesoscopic系统为对运输和测量的描述使用。评论包含重要修正案,澄清在主人方程和他们的有效性的推导的微妙的点。这在这个题目上完成更早的工作。推导不假定弱结合,这被表明环境和水库,而是需要仅仅高偏导状况。这个条件为Markovian主人方程的有效性是很必要的,广泛地为对不同物理过程的现象学的描述使用。
简介:Inthispaper,recentmeasurementsoftipvortexflowwithandwithoutcavitationcarriedoutinCavitationMechanismTunnelofChinaShipScientificResearchCenter(CSSRC)arepresented.TheelliptichydrofoilwithsectionNACA662-415wasadoptedastestmodel.High-speedvideo(HSV)camerawasusedtovisualizethetrajectoryoftipvortexcoreandtheformoftipvortexcavitation(TVC)indifferentcavitationsituations.LaserDopplervelocimetry(LDV)wasemployedtomeasurethetipvortexflowfieldinsometypicalsectionsalongthevortextrajectorywiththecaseofcavitationfree.Stereoparticleimagevelocimetry(SPIV)systemwasusedtomeasurethevelocityandvorticitydistributionswithandwithoutcavitation.Seriesmeasurementresultssuchasvelocityandvorticitydistributions,thetrajectoryoftipvortexcore,thevortexcoreradius,cavitysizeandcavitationinceptionnumberwereobtained.Theresultsdemonstratedthattheminimumpressurecoefficientinthevortexcoreobtainedbyflowfieldmeasurementwasquitecoincidentwiththetipvortexcavitationinceptionnumberobtainedundertheconditionofhighincomingvelocityandlowaircontent.AndTVCwoulddecreasethevortexstrengthcomparingwiththecasewithoutcavitation.
简介:Inthisstudy,thepracticalmethodologiesaredescribedforthedeterminationofthefactorsfortheselfabsorptioneffect(Fs),spectralinterferences(Fcsi),andtruecoincidencesummingeffects(Fcoi),whichareusedindirectgamma-spectrometricmeasurementofradionuclidessuchas210Pb,238U,234Th,226Ra,214Pb,228Ac,208Tl,214Bi,137Csand40Kinsamples.Tovalidatetheappliedmethods,certifiedreferencematerials(CRMs)oflakeandstreamsedimentsweremeasuredwithann-typeGermanium(Ge)detector-calibratedusingamultinuclidereferencesource.Thehighestself-absorptioncorrectionfactorsrangedfromFs1.44-2.10for46.5keVpeak(210Pb)andFs?1.25-1.60for63.3keVpeak(234Th)lyinginthelowenergyregionofthespectrum.Thesystematicinfluencewasobservedfor186.2keV(226Ra)peakduetospectralinterferenceswiththe235Ucontribution.Forthispeak,Fcsiischangedfrom0.921to0.955.Additionally,thepresentstudysuggeststhattruecoincidencesumming(TCS)effectsarenotdominant,exceptfor208Tland214BiforwhichFcoirangedfrom1.179to1.192anrangedfrom1.140to1.151,respectively.
简介:Anonlinearitymeasurementofthecharge-coupleddevice(CCD)arrayspectrometerusingfluxadditionandcomparisonmethodisdescribed.Thelightwithvariouscolorsfromthecolorfullightemittingdiode(LED)lightsourceisappliedtomeasurethenonlinearityofthespectrometeratdifferentwavelengths,respectively.Anhigh-endCCDarrayspectrometeristested.ForcolorfulLEDlightsources,thenonlinearityfactorsoftheCCDarrayspectrometer(absolutevalue)areasfollows:k<0.8%forwhitelight,k<1.1%forredlight,k<2.2%forgreenlightandk<4.7%forbluelight.Byusingthosequasi-monochromaticlightsources,itisshownthatthenonlinearitydependsonthewavelength.Itisimportanttobewarinessaboutthespectralnonlinearityandrelateduncertaintyevaluationwhenthenarrow-bandlightsourceistested.
简介:Thestressintensityfactor(SIF)isacriticalparameterassociatedwiththefracturebehaviourofmaterials.Inthispaper,weselectthedisplacementfunctionaroundacracktipastheshapefunctionofthedigitalimagecorrelation(DIC),whichmakesitpossibletodirectlycalculatetheSIFbythecorrelationscheme.Moreover,weuseanon-rectangularsubset,whichcanreducetheinfluenceofplasticdeformationandcrackwidthontheDICmeasurementaccuracy.WemeasuredtheSIFofamodeIcrackinasuper-hardaluminiumalloyspecimentoverifytheperformanceoftheproposedmethod.OurexperimentalresultsshowthataDICwithaspecificshapefunctioncanbeusedtoaccuratelyandefficientlycalculatetheSIF.Furthermore,wealsopresentapracticalapplicationofourproposedmethodfordeterminingtheSIF,crackpropagationangleandcracktipdisplacement.
简介:生物织物的吸收系数是在biomedicine的一个重要参数,但是它的决心仍然是挑战。在这份报纸,我们用集中photoacoustic成像技术和圆柱的扩散纤维(CDF)的内部轻照耀确定建议一个方法目标光吸收系数。为墨水吸收器的吸收系数第一在一样的刺激通过photoacoustic和spectrophotometric大小被决定,它表明这个方法的可行性。另外,有几集中的墨水吸收器的光吸收系数被测量。最后,二维的扫描photoacoustic图象被获得。光吸收系数测量和吸收器的同时的photoacoustic成像non-invasively是方法的典型特征。这个方法能为血氧浸透,基于吸收的成像和治疗的非侵略的决心起一个重要作用。
简介:为紧张和温度测量的一个光纤维传感器与纤维基于长时期纤维栅栏(LPFG)串联了布拉格栅栏(FBG)结构理论上并且试验性地被建议了并且认识到。有类似的敏感的二微观结构不能被用于的理论分析表演加倍参数测量。LPFG是由CO2激光的micromachined,并且FBG是由excimer激光的micromachined。为确认和比较,二FBG和一LPFG与三条传播山谷被串联,也就是在1536.3nm,在1551.2nm的LPFG山谷,和在1577.3nm的FBG2山谷的FBG1山谷。建议传感器的温度和紧张特征在4570椠歮愠獢牯敢獲愠敲映物瑳祬搠瑥牥業敮?桴潲杵?桰瑯慯潣獵楴?湡?灳'虪沟茲滀髷疇罐鏇V畳敲敭瑮?瑡琠敨猠浡?被测量硥楣慴楴湯?桷捩?敤潭獮牴瑡獥琠敨映慥楳楢楬祴漠?桴獩洠瑥潨d
简介:TheprecisionofplasmaelectrondensityandFaradayrotationanglemeasurementisakeyindicatorforfar-infraredlaserinterferometer/polarimeterplasmadiagnosis.Toimprovetheprecision,anewmulti-channelhighsignal-to-noiseratioHCOOHinterferometer/polarimeterhasbeendevelopedontheHL-2Atokamak.Ithasahigherlevelrequirementforphasedemodulationprecision.Thispaperintroducesanimprovedreal-timefastFouriertransformalgorithmbasedonthefieldprogrammablegatearray,whichsignificantlyimprovestheprecision.Wealsoapplyareal-timeerrormonitoringmodule(REMM)andastableerrorinhibitingmodule(SEIM)forprecisioncontroltodealwiththeweaksignal.Wetesttheinterferometer/polarimetersystemwiththisimprovedprecisioncontrolmethodinplasmadischargeexperimentsandsimulationexperiments.Theexperimentalresultsconfirmthattheplasmaelectrondensityprecisionisbetterthan1/3600fringeandtheFaradayrotationanglemeasurementprecisionisbetterthan1/900fringe,whilethetemporalresolutionis80ns.ThisperformancecanfullymeettherequirementsofHL-2A.
简介:WeinvestigatethesensitivityoftheangularrotationmeasurementwiththemethodofhomodynedetectioninSU(2)andSU(1,1)interferometersbyemployingorbitalangularmomentum(OAM).BycombiningacoherentbeamwithavacuumbeaminanSU(2)interferometer,wegetthesensitivityoftheangularrotationmeasurementas1/(2N1/2l).WecansurpassthelimitoftheangularrotationmeasurementinanSU(1,1)interferometerbycombiningacoherentbeamwithavacuumbeamorasqueezedvacuumbeamwhentheprobebeamhasOAM.Withoutinjection,thesensitivitycanreach1/(2N1/2l).Inaddition,byemployinganotherconstructionofanSU(1,1)interferometerwherethepumpbeamhasOAM,withthesameinjectionofanSU(1,1)interferometer,thesensitivityoftheangularrotationmeasurementcanbeimprovedbyafactorof2,reaching1/(4Nl).Theresultsconfirmthepotentialofthistechnologyforprecisionmeasurementsinangularrotationmeasurements.