学科分类
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98 个结果
  • 简介:树修剪是一个有效算法减少范围察觉(SD)的复杂性为多重输入多重产量(MIMO)通讯系统。怎么决定修剪统治的树,以及由在表演之间的折衷和复杂性能被完成的,仍然是一个开的问题。在这份报纸,修剪算法的一棵树基于最小的均方差(MMSE)被建议察觉。建议算法自从MMSE察觉的复杂性,第一预先形成MMSE察觉是很低的。然后,修剪的限制将被放根据MMSE答案的放大路径度量标准。复杂性和表演上的规模因素和他们的影响的选择也被讨论。通过分析和模拟,复杂性与可以忽略的表演降级和另外的计算显著地被减少,这被显示出。

  • 标签: MMSE MIMO 检测器 修剪 树木 多输入多输出
  • 简介:Intrusiondetectioncanbeessentiallyregardedasaclassificationproblem,namely,dis-tinguishingnormalprofilesfromintrusivebehaviors.Thispaperintroducesboostingclassificationalgorithmintotheareaofintrusiondetectiontolearnattacksignatures.Decisiontreealgorithmisusedassimplebaselearnerofboostingalgorithm.Furthermore,thispaperemploysthePrincipleCom-ponentAnalysis(PCA)approach,aneffectivedatareductionapproach,toextractthekeyattributesetfromtheoriginalhigh-dimensionalnetworktrafficdata.KDDCUP99datasetisusedintheseex-perimentstodemonstratethatboostingalgorithmcangreatlyimprovetheclassificationaccuracyofweaklearnersbycombininganumberofsimple“weaklearners”.Inourexperiments,theerrorrateoftrainingphaseofboostingalgorithmisreducedfrom30.2%to8%after10iterations.Besides,thispaperalsocomparesboostingalgorithmwithSupportVectorMachine(SVM)algorithmandshowsthattheclassificationaccuracyofboostingalgorithmislittlebetterthanSVMalgorithm’s.However,thegeneralizationabilityofSVMalgorithmisbetterthanboostingalgorithm.

  • 标签: 入侵检测 BOOSTING算法 机器学习 网络安全
  • 简介:Themeasurementtechniquesoffemtosecondspectroscopyareeffectivemethodtoinvestigateultrafastdynamics,theyarewidelyusedinthefieldsofphysics,chemistryandbiology.Inthispaper,theprinciple,experimentsetupandtheapproachestodealwiththeexperimentdatawerepresented.Thendifferentmeasurementtechniquessuchastransientabsorptionspectroscopy,photonechoes,opticalKerreffectanddegeneratefour-wavemixingwereexplainedwithspecialexamples.Atlast,theapplicationprospectofmeasurementtechniquesoffemtosecondspectroscopywasforecasted.

  • 标签: 飞秒激光器 超快动力学 第四混频 泵浦探测
  • 简介:Modernnetworksystemshavemuchtroubleinsecurityvulnerabilitiessuchasbufferoverflow,bugsinMicrosoftInternet,sensornetworkroutingprotocoltoosimple,securityflawsofapplications,andoperatingsystems.Moreover,wirelessdevicessuchassmartphones,personaldigitalassistants(PDAs),andsensorshavebecomeeconomicallyfeasiblebecauseoftechnologicaladvancesinwirelesscommunicationandmanufacturingofsmallandlow-costsensors.Therearetypologiesofvulnerabilitiestobeexploitedinthesedevices.Inordertoimprovesecurities,manymechanismsareadopted,includingauthentication,cryptography,accesscontrol,andintrusiondetectionsystems(IDS).Ingeneral,intrusiondetectiontechniquescanbecategorizedintotwogroups:misusedetectionandanomalydetection.Themisusedetectionsystemsusepatternsofwell-knownattacksorweakspotsofthesystemstoidentifyintrusions.Theweaknessofmisusedetectionsystemsisunabletodetectanyfuture(unknown)intrusionuntilcorrespondingattacksignaturesareintrudedintothesignaturedatabase.Anomalydetectionmethodstrytodeterminewhetherthedeviationisfromtheestablishednormalusagepatternsornot.Thecriticalsuccessofanomalydetectionreliesonthemodelofnormalbehaviors.

  • 标签: 入侵检测系统 异常检测方法 传感器网络 安全漏洞 个人数字助理 误用检测
  • 简介:Oneofthemainrequirementsofcognitiveradiosystemsistheabilitytodetectthepresenceoftheprimaryuserwithfastspeedandpreciseaccuracy.Toachievethat,apossibletwo-stagespectrumsensingschemeissuggestedinthispaper.Morespecifically,afastspectrumsensingalgorithmbasedontheenergydetectionisintroducedfocusingonthecoarsedetection.Acomplementaryfinespectrumsensingalgorithmadoptsone-ordercyclostationarypropertiesofprimaryuser'ssignalsintimedomain.Sincetheone-orderfeaturedetectionisperformedintimedomain,thereal-timeoperationandlow-computationalcomplexitycanbeachieved.Also,itdrasticallyreduceshardwareburdensandpowerconsumptionasopposedtotwo-orderfeaturedetection.Thesensingperformanceoftheproposedmethodisstudiedandtheanalyticalperformanceresultsaregiven.Theresultsindicatethatbetterperformancecanbeachievedinproposedtwo-stagesensingdetectioncomparedtotheconventionalenergydetector.

  • 标签: 循环平稳特性 无线电系统 检测技术 特征检测 能量检测 一阶
  • 简介:Theautomaticdetectionoffacesisaveryimportantproblem.Theeffectivenessofbiometricauthenticationbasedonfacemainlydependsonthemethodusedtolocatethefaceintheimage.Thispaperpresentsahybridsystemforfacesdetectioninunconstrainedcasesinwhichtheillumination,pose,occlusion,andsizeofthefaceareuncontrolled.Todothis,thenewmethodofdetectionproposedinthispaperisbasedprimarilyonatechniqueofautomaticlearningbyusingthedecisionofthreeneuralnetworks,atechniqueofenergycompactionbyusingthediscretecosinetransform,andatechniqueofsegmentationbythecolorofhumanskin.Awholeofpictures(facesandnofaces)aretransformedtovectorsofdatawhichwillbeusedforlearningtheneuralnetworkstoseparatebetweenthetwoclasses.Discretecosinetransformisusedtoreducethedimensionofthevectors,toeliminatetheredundanciesofinformation,andtostoreonlytheusefulinformationinaminimumnumberofcoefficientswhilethesegmentationisusedtoreducethespaceofresearchintheimage.Theexperimentalresultshaveshownthatthishybridizationofmethodswillgiveaverysignificantimprovementoftherateoftherecognition,qualityofdetection,andthetimeofexecution.

  • 标签: 混合动力系统 侦测 自动检测功能 离散余弦变换 鲁棒 人脸图像
  • 简介:Thispaperpresentsahumandetectionsysteminavision-basedhospitalsurveillanceenvironment.Thesystemiscomposedofthreesubsystems,i.e.backgroundsegmentationsubsystem(BSS),humanfeatureextractionsubsystem(HFES),andhumanrecognitionsubsystem(HRS).ThecodebookbackgroundmodelisappliedintheBSS,thehistogramoforientedgradients(HOG)featuresareusedintheHFES,andthesupportvectormachine(SVM)classificationisemployedintheHRS.Bymeansoftheintegrationofthesesubsystems,thehumandetectioninavision-basedhospitalsurveillanceenvironmentisperformed.Experimentalresultsshowthattheproposedsystemcaneffectivelydetectmostofthepeopleinhospitalsurveillancevideosequences.

  • 标签: 视频监控 人体检测 检测系统 特征提取 支持向量机 子系统
  • 简介:Whenthereturnscomefromtwoormoreunresolvedtargets(thesignalsarenotresolvedinthefrequencyortimedomains)inamonopulseradarsystem,thedirection-of-arrival(DOA)estimateindicatedbythemonopulseratioisnotthetrueinformationofthetrackedtarget.Thenthetrackingsystemsisinfluenced.Anapproachhasbeenproposedtodetectwhetherthereturnscomefromasingletargetortwounresolvedtargets.Theaboveapproachisextendedfromtwotothreeunresolvedtargets.Thesimulationindicatesthatthedetectionprobabilityunderthethreeunresolvedtargetsisnotsuretoexceedthedetectionprobabilityunderthetwounresolvedtargets.

  • 标签: DOA 单脉冲雷达 检测概率 时域
  • 简介:Forfacedetectionundercomplexbackgroundandillumination,adetectionmethodthatcombinestheskincolorsegmentationandcost-sensitiveAdaboostalgorithmisproposedinthispaper.First,byusingthecharacteristicofhumanskincolorclusteringinthecolorspace,theskincolorareainYCbCrcolorspaceisextractedandalargenumberofirrelevantbackgroundsareexcluded;thenforremedyingthedeficienciesofAdaboostalgorithm,thecost-sensitivefunctionisintroducedintotheAdaboostalgorithm;finallytheskincolorsegmentationandcost-sensitiveAdaboostalgorithmarecombinedforthefacedetection.Experimentalresultsshowthattheproposeddetectionmethodhasahigherdetectionrateanddetectionspeed,whichcanmoreadapttotheactualfieldenvironment.

  • 标签: 人脸检测 ADABOOST算法 复杂背景 照度 肤色分割 颜色空间
  • 简介:Inordertoovercometheexistingdisadvantagesofofflinelasershockpeeningdetectionmethods,anonlinedetectionmethodbasedonacousticwavesignalsenergyisprovided.Duringthelasershockpeening,anacousticemissionsen-soratadefinedpositionisusedtocollecttheacousticwavesignalsthatpropagateintheair.Theacousticwavesignalissampled,stored,digitallyfilteredandanalyzedbytheonlinelasershockpeeningdetectionsystem.Thenthesystemgetstheacousticwavesignalenergytomeasurethequalityofthelasershockpeeningbyestablishingthecorrespondencebetweentheacousticwavesignalenergyandthelaserpulseenergy.ThesurfaceresidualstressesofthesamplesaremeasuredbyX-raystressanalysisinstrumenttoverifythereliability.Theresultsshowthatboththesurfaceresidualstressandacousticwavesignalenergyareincreasedwiththelaserpulseenergy,andtheirgrowthtrendsareconsistent.Finally,theempiricalformulabetweenthesurfaceresidualstressandtheacousticwavesignalenergyisestablishedbythecubicequationfitting,whichwillprovideatheoreticalbasisforthereal-timeonlinedetectionoflasershockpeening.

  • 标签: LASER shock PEENING ACOUSTIC WAVE LASER
  • 简介:Thispaperpresentsafault-detectionmethodbasedonthephasespacereconstructionanddataminingapproachesforthecomplexelectronicsystem.TheapproachforthephasespacereconstructionofchaotictimeseriesisacombinationalgorithmofmultipleautocorrelationandΓ-test,bywhichthequasi-optimalembeddingdimensionandtimedelaycanbeobtained.Thedataminingalgorithm,whichcalculatestheradiusofgyrationofunit-masspointaroundthecentreofmassinthephasespace,candistinguishthefaultparameterfromthechaotictimeseriesoutputbythetestedsystem.Theexperimentalresultsdepictthatthisfaultdetectionmethodcancorrectlydetectthefaultphenomenaofelectronicsystem.

  • 标签: 数据采集 故障检测 混沌时间序列 相位空间重建 拓扑结构
  • 简介:动态察觉基于光学传感器和变化雷达是一个新方法检测飞行帮助灯的发光紧张。光学传感器能得到每盏灯的照明信息,变化雷达得到距离信息,然后数据合并技术被用来计算每盏灯的发光紧张。修改这个动态察觉系统的错误的一个方法被介绍。它由基于光学传感器使用山峰价值察觉估计每盏灯的精确位置避免累积错误和测量搬运人的旅行错误,然后修改光的纵向距离信息和横向的位置信息。察觉和变化系统的表演被一些实验验证并且出现在图画。

  • 标签: 光学传感器 测距雷达 动态检测 发光强度 飞行辅助照明
  • 简介:Compressivesensingisarevolutionaryideaproposedrecentlytoachievemuchlowersamplingrateforsignals.Intheimageapplicationwithlimitedresourcesthecameradatacanbestoredandprocessedincompressedform.Analgorithmformovingobjectandregiondetectioninvideousingacompressivesamplingisdeveloped.Thealgorithmestimatesmotioninformationofthemovingobjectandregionsinthevideofromthecompressivemeasurementsofthecurrentimageandbackgroundscene.Thealgorithmdoesnotperforminversecompressiveoperationtoobtaintheactualpixelsofthecurrentimagenortheestimatedbackground.Thisleadstoacomputationallyefficientmethodandasystemcomparedwiththeexistingmotionestimationmethods.Theexperimentalresultsshowthatthesamplingratecanreduceto25%withoutsacrificingperformance.

  • 标签: 视频压缩 移动物体 抽样框 侦测 数据图像 采样算法
  • 简介:Asimpleinstrumentforthereal-timemeasurementofalgaeconcentrationandmappingdescribed.Theinstrumentusesapulsedshortarcxenonflashlampastheexcitedlightsources.Boththeexcitinglightandthefluorescencefromalgaechlorophyllaretransmittedalongafiberbundle.Themeasurementsensivitivityisanalyzedandtheexperimentresultisgiven.Theinstrumentispracticaltoin-situmeasurementatsea.

  • 标签: 光纤荧光计 海藻浓度 时实测量 叶绿素α
  • 简介:Visualfiredetectiontechnologiescandetectfireandalarmwarningsearlierthanconventionalfiredetectors.Thisstudyproposesaneffectivevisualfiredetectionmethodthatcombinesthestatisticalfirecolormodelandsequentialpatternminingtechnologytodetectfireinanimage.Furthermore,theproposedmethodalsosupportsreal-timefiredetectionbyintegratingadaptivebackgroundsubtractiontechnologies.Experimentalresultsshowthattheproposedmethodcaneffectivelydetectfireintestimagesandvideos.ThedetectionaccuracyoftheproposedhybridmethodisbetterthanthatofCelik’smethod.

  • 标签: 火灾探测技术 序列模式 视觉 检测图像 火灾探测器 探测方法
  • 简介:交通灯察觉和识别为在城市的环境的自治开车是必要的。一个照相机基于算法因为即时柔韧的交通灯察觉和识别被建议,并且特别为自治车辆设计了。尽管当前的可靠交通灯识别算法操作在进行中的井,他们中的大多数主要在一个固定位置为察觉被设计,在真实世界的条件下面的自治车辆上的效果仍然是有限的。一些方法在自治车辆上完成高精确性,但是没有高精确的priori地图的帮助,他们不能通常工作。作者为这个问题介绍了一个基于照相机的算法。处理流动的图象能被划分成三步,包括预处理,察觉和识别。第一,red-green-blue(红绿蓝)颜色空间作为预处理的主要内容被变换成hue-saturation-value(HSV)。在察觉步,同时,先验的颜色阀值方法被用于起始的过滤优先的知识被执行扫描景色以便快速建立候选人区域。为识别,面向的坡度(公猪)的这张文章使用直方图展示并且也支持向量机器(SVM)认出交通灯的状态。我们的自治车辆上的建议系统被评估。与投票的计划,建议罐头在城市的enviroment为自治车辆提供足够的精确性。

  • 标签: 自动驾驶汽车 识别算法 交通灯 检测 城市环境 交通信号灯
  • 简介:Inmausoleummurals,existingbubblesareonekindofthemostharmfuldefectsfortherepairandprotectionofrelics.Forthisreason,itisnecessarytodetectbubbles,especiallytheoneswithsmallsize.Amethodtodetectthesmallbubbleswithenhancedterahertz(THz)imagesisproposed.Tosimulatethebubblesinthemausoleummurals,circulargrooveshavebeenhiddenintheplasterandthenmeasuredbytheTHzreflectedtimedomainspectroscopyimagingsystem.Toobservethesmallbubblesinmurals,acomprehensiveenhancementalgorithmisadoptedtoprocesstheobtainedTHzimages.Withtheenhancedmethod,thecirculargroovesinthemuralscanbeobservedclearly,evenforthecirculargroovewithadiameterof1.5mm.Theresultsindicatethattheproposedcomprehensivemethodcanbeusedtodetectthetinydefectsofmurals.

  • 标签:
  • 简介:Whentheclassicalconstantfalse-alarmrate(CFAR)combinedwithfuzzyC-means(FCM)algorithmisappliedtotargetdetectioninsyntheticapertureradar(SAR)imageswithcomplexbackground,CFARrequiresblock-by-blockestimationofcluttermodelsandFCMclusteringconvergestolocaloptimum.Toaddresstheseproblems,thispaperpro-posesanewdetectionalgorithm:knowledge-basedcombinedwithimprovedgeneticalgorithm-fuzzyC-means(GA-FCM)algorithm.Firstly,thealgorithmtakestargetregion’smaximumandaverageintensity,area,lengthoflongaxisandlong-to-shortaxisratiooftheexternalellipseasfactorswhichinfluencethetargetappearingprobability.Theknowledge-baseddetectionalgorithmcanproducepreprocessresultswithouttheneedofestimationofcluttermodelsasCFARdoes.AfterwardtheGA-FCMalgorithmisimprovedtoclusterpre-processresults.IthasadvantagesofincorporatingglobaloptimizingabilityofGAandlocaloptimizingabilityofFCM,whichwillfurthereliminatefalsealarmsandgetbetterresults.TheeffectivenessoftheproposedtechniqueisexperimentallyvalidatedwithrealSARimages.

  • 标签: 目标检测 知识 改进遗传算法 全局寻优能力 FCM聚类 模糊C均值
  • 简介:DespiteextensiveresearchonR-trees,mostoftheproposedschemeshavenotbeenintegratedintoexistingDBMSowingtothelackofprotocolsofconcurrencycontrol.R-linktreeisanacceptabledatastructuretodealwiththisissue,butproblemslikephantomstillexist.Inthispaper,wefocusonaconflictdetectionschemebasedonR-linktreeforcompleteconcurrencycontrol.Anin-memoryoperationcontrollistisdesignedtosuspendconflictingoperations.Themainfeaturesofthisapproachare(1)itcanbeimplementedeasilyanddoesnotneedanyextrainformation;(2)Nodeadlocksareinvolvedinlockingscheme;(3)Non-conflictingoperationsarenotrestricted;and(4)PhantomproblemsinR-linktreeareavoidedthroughbeforehandpredication.Theexperimentresultsshowthatthisschemeiscorrectandgainsbettersystemperformance.

  • 标签: 冲突探测 协作控制 R联接树 幻想 多维数据结构
  • 简介:Anoveladaptiveswitchingfilter(ASF)basedondirectionaldetectionisproposedfordenoisingtheimagesthatarehighlycorruptedbyimpulsenoise.Theproposedalgorithmemploysanefficientnoisedetectionmechanism.Itfirstemploysanefficientmethodtoestimatethedifferencesbetweenthecurrentpixelanditsneighborsalignedwith28directions.Thecurrentnoisepixelisreplacedbyamedianorameanvaluewithinanadaptivefilterwindowwithrespecttodifferentnoisedensities.Experimentalresultsshowthattheproposedapproachcannotonlyachieveverylowmiss-detectionratioandfalse-alarmratioevenuptohighnoisecorruption,butalsopreservethedetailedinformationofanimageverywell.

  • 标签: 自适应滤波器 过滤器 脉冲检测 切换 相邻像素 脉冲噪声