简介:WeproposeapromisingschemetodecelerateaCWmolecularbeambyusingared-detunedquasi-cwsemi-Gaussianlaserbeam(SGB).WestudythedynamicalprocessofthedecelerationforaCWdeuteratedammonia(ND3)molecularbeambyMonte-Carlosimulationmethod.OurstudyshowsthatwecanobtainaND3molecularbeamwitharelativeaveragekineticenergylossofabout10%andarelativeoutputmolecularnumberofmorethan90%byusingasinglequasi-cwSGBwithapowerof1.5kWandamaximumopticalwelldepthof7.33mK.
简介:Aliquid-nitrogen-cooledTm,Ho:YLFlaserisconstructedwitha10-mm-longTm(6%)andHo(0.5%)co-dopedyttriumlithiumfluoridecrystalpumpedbyalaserdiodeoperatingat792nm.ThelaseroutputpowerisimprovedbycoolingtheTm,Ho:YLFcrystalfrom300to77K.Whenthecrystaliskeptat77K,thelaserthresholdpumppoweris230mW,theslopeefficiencyis27.4%,andthemaximumoptical-to-opticalefficiencyis19.9%.Atthesametime,therelationbetweentheinputpowerandtheoutputpoweratdifferenttemperaturesisobtained.
简介:TheenergymodelwasfoundedtocalculatethecriticalpowerofkeyholeformationbyusingthelimitprincipleinCW(continuouswave)Nd:YAGlaserdeeppenetrationweldingprocess.Themodelwasvalidatedbyexperiments.Theresultsshowthattherearetwoerrorsbetweenthecalculatedcriticalpowerofkeyholeformationandthatofexperiments:oneisthatthecalculatedresultsislessthanthoseofexperiments,whichiscausedbynotconsideringtheenergylossby!heatconductioninthemodelofkeyholeformation.Theotheristhatthereis0/9mmerrorbetweentheaxisofthecalculatedcurveofcriticalpowerwithlocationoflaserfocusandthatofexperimentalcurve,whichisinducedbytheexcursionoflaserfocusinlaserdeeppenetrationwelding.Atlast,thetwoerrorswererevisedaccordingtotheanalysesoftheerrors.
简介:针对基于周期模糊函数的伪码调相连续波雷达信号的参数提取,分析了在有限采集时间下噪声对参数估计精度的影响。首先推导了伪码调相连续波雷达信号的周期模糊函数,给出了基于周期模糊函数的参数估计方法;然后分析了参数估计受噪声影响的原因,推导了在模糊函数变换中,这些由噪声所产生项(不期望项)的均值和方差,并进行了仿真分析。结果表明,截获信号模糊函数的噪声项方差及噪声功率大小与有限采样时间有关,随着采样数据的增大,噪声的方差趋于无限小,对参数估计精度的影响也越来越小。
简介:AsimulationmethodforthethermalanalysisofInAlAs/InGaAs/InPmid--infraredquantumcascadelasers(QCLs)basedonfinite--elementmethod(FEM)ispresented.ThethermaldistributionoftheQCLsonsubstrate--sideorepilayer--sidemountingformsissimulatedandtheresultsarecompared.Resultsshowthattheepilayer--sidemountingformhasmuchbetterheatdissipationcapabilitythanthesubstrate--sidemounting.
简介:摘要电涡流测功机和其他的测量设备不同的是,它即是测量设备又是发动机的负载,发动机的功率完全消耗在侧功机上,通过改变测功机的励磁电流,测功机可以改变发动机的负荷,检测发动机在各种负载下的运行情况。