简介:Asimpleandeffectivegreedyalgorithmforimageapproximationisproposed.Basedonthematchingpursuitapproach,itischaracterizedbyareducedcomputationalcomplexitybenefitingfromtwomajormodifications.First,ititerativelyfindsanapproximationbyselectingMatomsinsteadofoneatatime.Second,theinnerproductcomputationsareconfinedwithinonlyafractionofdictionaryatomsateachiteration.Themodificationsareimplementedveryefficientlyduetothespatialincoherenceofthedictionary.Experimentalresultsshowthatcomparedwithfullsearchmatchingpursuit,theproposedalgorithmachievesaspeed-upgainof14.4~36.7timeswhilemaintainingtheapproximationquality.
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.
简介:如何使网络的主干与支干的连接既能满足带宽需要又能满足不同的传输距离的需求呢?长城公司于前不久推出了金长城GES-1524M新款交换机,该产品是国内首家推出的,能从100M直接升级至1000M的通用型交换机产品。金长城GES-1524M交换机基于性能高强而便于扩展的设计思想,通过提供一个集成于单一机箱的10/100MbpsUTP快速以太网接口和1个插槽,构架了一个高速灵活的以太网主干解决方案。对于主干与支干的连接来说,GES-1524M交换机提供一种可扩展的灵活配置插槽,其1000Base-LX最大传输距离可达10km,100Base-FX最大传输距离可达60km。金长城GES-1524M交换机,不仅为用户提供从核心主干到分支的全系列介质和全系列传输速率的连接,而且为到桌面提供了较高的带宽。长城推出GES-1524M新款交换机
简介:Inrecentyears,thepotentialofrenewablegreenenergysourceshasbeenextensivelystudied.Theproventechnologywhichisphotovoltaicsolarcellsstrictlydependsondaylightandproduceslow-efficiently.Toovercometherestrictions,onetechnologystudiedisthroughharvestingthethermalradiationenergywhichcanprovidea24-hourenergysource.Thecontinuityofenergysourcespromisesverygoodenergyconversionespeciallyformilitaryapplications.Thisarticlepresentsanewstructurethatcanharvesttheabundantthermalradiationenergyintousableenergyatthewavelengthof10μm.Arectangularstructurewithaperturbationslitwasdesignedtointegratewitharectifiercircuitforgreenenergyconversion.Theslittunneljunctionguidedtheelectromagneticfieldintoajunctionwheretheenergycouldbecollectedandconverted.Anenhancementfactorofapproximately110.6canbeachievedbyaperturbationslitlengthof1.0μm.Theresultsextractedfromtheproposeddesignpromiseabettercandidatetoovercomethedisadvantagesofphotovoltaicsolarcellsforenergyharvestingdevices.