简介：CognitiveRadio(CR)systembasedonOrthogonalFrequencyDivisionMultipleAccess(OFDMA),suchasWirelessRegionalAreaNetworks(WRAN)andWorldwideInteroperabilityforMicrowaveAccess(WiMAX),oftenattempttoimproveperformanceviadynamicradioresourcemanagement,whichischaracterizedasconcurrentprocessingofdifferenttrafficandnondeterministicsystemcapacity.Itisessentialtodesignandevaluatesuchcomplexsystemusingpropermodelingandanalysistools.Inthepreviouswork,mostofthecommunicationsystemsweremodeledasMarkovChain(MC)andStochasticPetriNets(SPN),whichhavetheexplicitlimitationinevaluatingadaptiveOFDMACRsystemwithwideareatraffic.Inthispaper,wedevelopanexecutabletop-downhier-archicalColoredPetriNet(CPN)modelforadaptiveOFDMACRsystem,andanalyzeitsperformanceusingCPNtools.TheresultsdemonstratethattheCPNcanmodeldifferentradioresourcemanage-mentalgorithmsinCRSystems,andtheCPNtoolsrequirelesscomputationaleffortthanMarkovmodelusingMatlab,withitsflexibilityandadaptabilitytothetrafficswhicharrivalintervalandprocessingtimearenotexponentiallydistributed.

简介：英国广播公司(无线电广播网)(BBCNetworkRadio)于1922年创办。该公司有5个对内广播电台，1个对外广播电台，用43种语言向全世界各国播放节目。英国广播公司(电视台)(BBCTelevision)于1936年开始播放电视，有两个台：BBC1主要播放新闻、宗教、体育、歌剧及少儿和娱乐节目，BBC2主要播放音乐、艺术、喜剧、教育及一些特别节目。

简介：Tocollectneuronalactivitydatafromawake,freelybehavinganimals,wedevelopedminiaturetelemetryrecordingsystem.Theintegratedsystemconsistsoffourmajorcomponents:1)Microelectrodesandmicro-driverassembly,2)analogfrontend(AFE),3)programmablesystemonchip(PSoC),and4)radiotransceiverandtheLabVIEWwereusedasaplatformforthegraphicuserinterface.Theresultshowedthesystemwasabletorecordandanalyzeneuronalrecordingsinfreelymovinganimalsandlastedcontinuouslyforatimeperiodofaweekormore.Thisisveryusefulforthestudyoftheinterdisciplinaryresearchofneuroscienceandinformationengineeringtechniques.Thecircuitsandarchitectureofthedevicescanbeadaptedforneurobiologyandresearchwithothersmallanimals.

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简介：INTRODUCTIONAsEnglishteachers,wehavedevotedalotoftimetotheteachingoflisteningcomprehensionusingradiobroadcasts.WebeganbyusingVOAnewsinspecialEnglishwithfreshmenandamixtureofnewsinspecialEnglishandstandardnewsbroadcastswithsophomores.LaterBBCnewswasused.Weaccumulatedaconsiderableamountofexperienceanddidsomeresearchintothedesignoflisteningcomprehensionexercises.Thisarticlediscusseshowlisteningabilitymaybeimprovedbyusingsuchbroadcasts.

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简介：ElectrondensityisakeyparametertocharacterizeMartianionosphericstructureanddynamics.BasedontheephemerisandauxiliaryinformationderivedfromtheSpacecraft,Planet,Instruments,C-matrix,andEvents(SPICE)toolkit,wecalculatedthebendingangleofsignalpathfromthefrequencyresidualsmeasuredbytheMarsExpressRadioScienceExperiment(MaRS)oftheMarsExpress(MEX)missionundertheassumptionofasphericallysymmetricionosphere.Westratifiedtheionosphereintolayersandassumedalinearchangeofbendinganglebetweenlayers,toderiveprofilesinradialdistanceofrefractivitywiththeoptimizedparametersofupperintegrallimitof4890kmandbaselinecorrectionboundaryof3690km.Meanwhile,wealsocomparedtheretrievedelectrondensityprofilesbetweenthefrequencyresidualsofthesingle-frequencyanddifferentialDopplerofthedual-frequency.Intotal,~640electrondensityprofilesofMartianionospherebetweenApril2004andApril2015wereretrievedsuccessfully.Thereare24profilesidentifiedmanuallythatexhibitanadditionalsporadiclayeroccurrencebelowthenormaltwo-layers.Wealsofoundthatthepeakaltitudeofthislayerincreaseswiththemainpeakaltitude.

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简介：第四代(4G)无线通讯系统被部署了或不久在许多国家被部署。与无线移动设备和服务的爆炸，然而，仍然有一些挑战，不能甚至被4G提供，例如光谱危机和内部房间的干扰。电信操作符转弯了承诺自己分享可得到的资源，包括硬件和软件资源。因此与相互的基础结构，‘integration’应该被加亮，特别在第五代(5G)被期望到的无线系统超过2020被部署。在文章的作者建议了潜在的细胞的体系结构，并且讨论了内部操作员的收音机接口为5G的基于的同步(肋骨)无线通讯系统。内部操作员的肋骨和典型情形的一个计划，与相应干扰的分析一起被给。分享的参数，内部操作员的肋骨的发信号的协作和为肋骨的信号(RS)设计也是的听的引用的分析执行了。

简介：ThesecondaryusageofspectrumhasbeeninvestigatedinCognitiveRadio(CR)networktoresolvingthespectrumscarcityissueinwirelesscommunication.WhenPrimaryUsers(PU)whoownthespectrumappear,spectrumhandoffisneededtomaintainthecommunicationsofSecondaryUsers.ButthedecisionmakingofspectrumhandoffisachallengeissueforCRnetwork,becausetheinputofdecisionmaking,whichobtainthroughspectrumsensing,isheterogeneousandinexact.Inthispaperwewillusefuzzylogiccontroltheorytosolvethisissueandmakeuseofnewinformationforhandoffoperation:theprobabilityofPU'soccupancyatacertainchannel.Ournewalgorithmcanmakemoreintelligentdecisioncomparedtosimpletraditionalspectrumhandoffdecisionmakingandreducetheprobabilityofspectrumhandoff,alsotheperformanceofSU'scommunicationcanbeenhanced.

简介：还记得那些校园里哑哑作响的广播台吗？还记得一到中午,或者临近晚饭时分就开始播音的校园广播吗？

简介：Influenceofpulsedpowertransmissiononradiowaveenvironmentisinvestigated.Thepowerpulsesaretransmittedintermittentlyinpulsedpowernetworkthatisalreadyproposedforanalternativeofupcomingsmartgrids.Incontrasttoconventionalpowertransmissionwithcontinuouselectriccurrentoflowfrequencysinewave,pulsedpowertransmissionmayaffectsurroundingfieldwithhighfrequencyradionoises.Inthispaper,basedontheanalysisofelectricfieldstrengtharoundapowerline,theradionoisesgeneratedbyvariousformsofpulsedpowertransmissionareevaluated.Asaresult,twopointsarederived.First,thoughthetotalofgeneratedradionoisepowerobviouslyexceedsthatofconventionalpowertransmissions,peakstrengthofelectricfieldratherfallsbehindtheconventionalone.Second,concerningtheinfluenceontheradiowaveofthelowestfrequency40kHzthatisactuallyusedforstandardtimeandfrequencysignal,thenoiseintensitypossiblyexceedstheweakradiosignaltoleranceaccordingtotheshapeofeachpowerpulsetransmitted.

简介：Inthisbriefreportweproposeasimplemodelbasedonthepropertiesofanelectriccapacitorundershort-circuitconditionsasapossiblemechanismofradioemissionsassociatedwithearthquakes.Thismodelcanbeconsideredascomplementarytoothermodelsconcerningthesameproblem.

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简介：Inrecentyears,radiooccultation(RO)technologymakinguseofglobalpositioningsystem(GPS)signalshasbeenexploitedtoobtainprofilesofatmosphericparametersintheneutralatmosphere.Inthispaper,theROrefractivityprofilesobtainedfromtheConstellationObservingSystemforMeteorology,IonosphereandClimate(COSMIC)missionarestatisticallycomparedwiththeobservationsof38radiosondestationsprovidedbytheAustralianBureauofMeteorologyduringtheperiodfrom15July2006through15July2007.Di?erentcollocationcriteriaarecomparedatfirst,andCOSMICROsoundingsthatoccurwithin3hoursand300kmofradiosondemeasurementsareusedforthefinalstatisticalcomparison.TheoverallresultsshowthattheagreementsbetweentheCOSMICrefractivityprofilesandtheradiosondesoundingsfromthe38stationsareverygoodat0–30kmaltitude,withmeanabsoluterelativerefractivitydeviationsoflessthan0.5%.Latitudinalcomparisonsindicatethattherearenegativerefractivitydeviationsinthelowertroposphereoverthelowlatitudeandmiddlelatituderegionsandlargestandarddeviationsexistinthelowertroposphereoflowlatituderegions,whichcanreachupto～6%.ThecomparisonsofCOSMICROrefractivityprofilesandradiosondeobservationsfor3polarstationsinfourdifferentseasonsindicatethattheaccuracyofGPSROprofilesisbetterintheAustralsummerandautumnthanintheAustralspringandwinterduringtheyearfromSeptember2006toAugust2007.

简介：这篇文章在认知收音机基于收到的信号力量介绍经典定位方法并且提出认知收到收音机的信号力量(CR-RSS)解决找到主要用户的第二等的用户的问题并且成功估计主要用户的地点和传播力量的本地化算法。通过认知收音机网络的建立，在CR-RSS途径评估第二等的用户，采样和环境因素的数字到结果。后果证明这个途径罐头有效地找到主要用户，在认知无线电的本地化的技术能帮助网络优化。