简介:Asimpleandeffectivegreedyalgorithmforimageapproximationisproposed.Basedonthematchingpursuitapproach,itischaracterizedbyareducedcomputationalcomplexitybenefitingfromtwomajormodifications.First,ititerativelyfindsanapproximationbyselectingMatomsinsteadofoneatatime.Second,theinnerproductcomputationsareconfinedwithinonlyafractionofdictionaryatomsateachiteration.Themodificationsareimplementedveryefficientlyduetothespatialincoherenceofthedictionary.Experimentalresultsshowthatcomparedwithfullsearchmatchingpursuit,theproposedalgorithmachievesaspeed-upgainof14.4~36.7timeswhilemaintainingtheapproximationquality.
简介:摘要:基于L波段250W的GAN功放管,本文成功实现一款800W的固态脉冲功率放大模块;实验结果表明,该脉冲功率放大器可应用于L频段高占空比脉冲功率发射机中。
简介:本文针对EXB841经典IGBT驱动电路存在的不足:过流保护阈值过高、存在虚假过流、负偏压不足,过流无保护自锁及无报警电路。因此,提出一款新型的IGBT模块驱动器TX—K841L,它延迟时间小,工作频率高,驱动能力强,可直接代换EXB841。通过实验测试其在逐波过流和连续过流时(实行软关断,PWM信号封锁)的情况,进一步验证了此驱动器的控制器端可靠而且稳定。而且它还可根据用户需要设定IGBT的短路阈值电压、保护盲区时间、软关断斜率,以及提供了故障反馈保护的接口,使产品的适用性得到极大提高,已经在逆变器、不问断电源、电焊机、伺服系统、轨道交通等领域获得了广泛的应用。
简介:Areviewontheprogressofpowerful2μmsilicafibersourcesinpastdecadesispresented.Wereviewthestate-of-the-artrecordsandrepresentativeachievementsof2μmhigh-average-powercontinuouswave,pulsedfiberlasersandamplifiers,andpowerfulsuperfluorescentsources.Challengeswhichlimitthefurtherpowerscalingof2μmsilicafibersourcesarediscussed,includingpumpingbrightnesslimitation,thermalproblem,andnonlineareffects.Potentialandpromisingroadmapstogobeyondtheselimitations,liketandempumpingandbeamcombining,arediscussed.Prospectsofpowerful2μmsilicafibersourcesarealsopresentedintheendofpaper.
简介:Atpresent,chaoticcommunicationshavebeenwidelystudied.However,theseresearchesmainlyfocusonthebinarysystemswhiletheresearchesofM-arychaoticcommunicationsarenotextensive.Tochangethesituation,achaosM-arymodulationmethodbasedonphaseplanepartitionofHamiltonmapisproposed.Firstly,thechaoticmodelofHamiltonmapanditsphaseplanefeaturesaredescribed,andthenthewayofcreatingthechaosM-arymodulationisdiscussed.Next,toevaluatetheproposedmethod,thesystemsimulationresultsandanalysisaregiven.Finally,thechaosM-arymodulationmethodisappliedtocommunications.
简介:Self-organizedIn0.5Ga0.5As/GaAsquantumislandstructureemittingat1.35μmatroomtemperaturehasbeensuccessfullyfabricatedbymolecularbeamepitaxy(MBE)viacycled(InAs)1/(GaAs)1monolayerdepositionmethod.Photoluminescence(PL)measurementshowsthatverynarrowPLlinewidthof19.2meVat300Khasbeenreachedforthefirsttime,indicatingeffectivesuppressionofinhomogeneousbroadeningofopticalemissionfromtheIn0.5Ga0.5Asislandsstructure.Ourresultsprovideimportantinformationforoptimizingtheepitaxialstructuresof1.3μmwavelengthquantumdot(QD)devices.