简介:A2-cmlongBragggratingwithreflectivityof~99.95%inB/Gecodopedopticalfiberwithouthydrogenloadingwascreatedbyphase-maskmethodwithapulsedKrFexcimerlaserat248nm.DCandACcomponentsofrefractiveindexchangewereanalyzedbymonitoringtransmissionspectrumevolutionduringthewritingprocessoffiberBragggrating.Therelationsoftheevolutionofcenterwavelengthandreflectivitywithnumberofpulseswererespectivelyinvestigated.
简介:随着广播式自动相关监视(ADS-B)技术的推广应用,作为ADS-B体系的组成部分的ADS-B地面站已经成为保障ADS-B使用效能的重要环节。在探讨ADS-B基本理论的基础上,对ADS-B地面站的架构、功能、规划与建设等方面进行了分析,并提出了相关设计方法和理念。
简介:Anautomaticdependentsurveillancebroadcast(ADS-B)systemhasserioussecurityproblems,andthedatacanbespoofedduringbroadcastingprecisepositioninformationofaircraft.AsolutionoftheADS-Bsystemdataauthenticationbasedontheellipticcurvecipher(ECC)andX.509certificateisproposed.ItcanavoidthekeydistributionproblembyusingthesymmetrickeyalgorithmandpreventtheADS-Bdatafrombeingspoofedthoroughly.ExperimentaltestresultsshowthatthesolutionisvalidandappropriateinADS-Buniversalaccesstransceiver(UAT)mode.
简介:Theopticalparametersforthreesamplesofintrinsic,dopedSianddopedMg(AlxGa1-x)yIn1-yPpreparedbytheMOCVDonGaAssubstrateweremeasuredbyusingellipsometryandwerecalculatedbythetwo-layerabsorptionfilmmodel.Theresultsobtainedwerediscussed.Thegrownratesandthicknessofoxidiclayerontheintrinsic(AlxGa1-x)yIn1-yPsurfaceexposedintheatmospherewerestudied.Alineardependenceofoxidiclayerthicknessonthetimewasobtained.