简介:Intheopennetworkenvironment,maliciousattackstothetrustmodelhavebecomeincreasinglyserious.Comparedwithsinglenodeattacks,collusionattacksdomoreharmtothetrustmodel.Tosolvethisproblem,acollusiondetectorbasedontheGNalgorithmforthetrustevaluationmodelisproposedintheopenInternetenvironment.Byanalyzingthebehavioralcharacteristicsofcollusiongroups,theconceptofflattingisdefinedandtheG-Ncommunityminingalgorithmisusedtodividesuspiciouscommunities.Onthisbasis,acollusioncommunitydetectormethodisproposedbasedonthebreakingstrengthofsuspiciouscommunities.Simulationresultsshowthatthemodelhashighrecognitionaccuracyinidentifyingcollusionnodes,soastoeffectivelydefendagainstmaliciousattacksofcollusionnodes.
简介:Animprovedgeneticalgorithmforsearchingoptimalparametersinn-dimensionalspaceispresented,whichencodesmovementdirectionanddistanceandsearchesfromcoarsetoprecise.Thealgorithmcanrealizeglobaloptimizationandimprovethesearchefficiency,andcanbeappliedeffectivelyinindustrialoptimization,dataminingandpatternrecognition.
简介:ThisletterpresentsanewchunkingmethodbasedonMaximumEntropy(ME)modelwithN-foldtemplatecorrectionmodel.Firsttwotypesofmachinelearningmodelsaredescribed.Basedontheanalysisofthetwomodels,thenthechunkingmodelwhichcombinestheprofitsofconditionalprobabilitymodelandrulebasedmodelisproposed.Theselectionoffeaturesandruletemplatesinthechunkingmodelisdiscussed.ExperimentalresultsfortheCoNLL-2000corpusshowthatthisapproachachievesimpressiveaccuracyintermsoftheF-score:92.93%.ComparedwiththeMEmodelandMEMarkovmodel,thenewchunkingmodelachievesbetterperformance.
简介:Blindrecognitionofconvolutionalcodesisnotonlyessentialforcognitiveradio,butalsofornon-cooperativecontext.Thispaperisdedicatedtotheblindidentificationofratek/nconvolutionalencodersinanoisycontextbasedonWalsh-Hadamardtransformationandblockmatrix(WHT-BM).Theproposedalgorithmconstructsasystemofnoisylinearequationsandutilizesallitscoefficientstorecoverparitycheckmatrix.Itisabletomakeuseoffault-tolerantfeatureofWHT,thusprovidingmoreaccurateresultsandachievingbettererrorperformanceinhighrawbiterrorrate(BER)regions.Moreover,itismorecomputationallyefficientwiththeuseoftheblockmatrix(BM)method.
简介:AgeneralizedspectralGreen’sfunctionformulationofN-layersubstratestructureisgivenwiththreedimensionsources,whichisasetofclosedformformulas.Afull-waveanalysismodelforrectangularmicrostripantennascoveredwithN-dielectriclayershasbeenestablishedbyusingtheabovespectralGreen’sfunction.Theunknownsurfacecurrentdensityontheniicrostrippatchforsuchstructureisfoundasasolutionofanintegralequation.TheinputVSWRandradiationpatternsoftheantennaarealsoobtained.Thenumericalresultshavebeenverifiedbytheexperimentalresults.
简介:Coexistenceandinteroperabilitybetween20MHzand40MHzdeviceandmodesofop-erationsarestressedinstandardIEEE802.11nsystem.Itismandatetoreportthebothsub-channelsstatestoMediumAccessControl(MAC)atreceiver,sincefor40MHzdevice,itshouldservenotonly20MHzbutalso40MHzsignalsreceiving.Bothenergydetectionandcarriersenseareemployedtodetectchannelstate.Inthecaseof20/40Mmode,thepowerdifferencebetweenthetwosub-channelsisalsodetectedinordertoreportthechannelstateaccurately.Thesimulationresultsdemonstratethattheperformanceoftheproposedmethodsaremuchbetterthanthemethodswhichjustemployenergydetection.Besides,thesimulationresultsshowthattheproposedmethodsensurethatthechannelsensingisnotaroadblockofIEEE802.11nsystemdesign.
简介:TheanalysisofsolarcellperformancehasbeendonebysimulatingtheexternalI-Vcharacteristicsofn^+/p/p^+singlecrystalsiliconsolarcellunderhighlightintensityand1.5airmass(AM).Thismethodallowsthemaximizationofsolarcellefficiency.Tofabricatelow-costn^+/p/p^+singlecrystalsiliconsolarcells,solidsourceofdopedphosphorousandboronwasused.