简介:ThisarticledescribesalocalerrorestimatorforGlimm'sschemeforhyperbolicsystemsofconservationlawsandusesittoreplacetheusualrandomchoiceinGlimm'sschemebyanoptimalchoice.Asaby-productofthelocalerrorestimator,theprocedureprovidesaglobalerrorestimatorthatisshownnumericallytobeaveryaccurateestimateoftheerrorinL1(R)foralltimes.Althoughthereispartialmathematicalevidencefortheerrorestimatorproposed,atthisstagetheerrorestimatormustbeconsideredad-hoc.Nonetheless,theerrorestimatorissimpletocompute,relativelyinexpensive,withoutadjustableparametersandatleastasaccurateasotherexistingerrorestimators.Numericalexperimentsin1-DforBurgers'equationandforEuler'ssystemareperformedtomeasuretheasymptoticaccuracyoftheresultingschemeandoftheerrorestimator.
简介:Inubiquitouscomputing,datashouldbeabletobeaccessedfromanylocation,andthecorrectnessofdatabecomesvitalduringthecommunication.Supposethatmanyuserssigndifferentmessagesrespectively,beforeforwardingorsendingthesemessages,thentheverifiermustspendalotofcomputingtimetoverifytheirsignatures.Consequently,theaggregatesignatureschemeisaneffectivemethodofimprovingefficiencyinthiskindofsystems,whichprovidestheconveniencefortheverifier.Inthispaper,weproposeanewcertificatelessaggregatesignatureschemewhichisefficientingeneratingasignatureandverification.ThisschemeisprovablysecureundertheextendedcomputationalDiffie-Hellmanassumption.
简介:Vehielesenlistedwitheomputing,sensingandcommunicatingdevicescancreatevehicularnetworks,asubsetofcooperativesystemsinheterogeneousenvironments,aimingatimprovingsafetyandentertainmentintraffic.Invehicularnetworks,avehicle’sidentityisassociatedtoitsowner’sidentityasauniquelinkage.Therefore,itisofimportancetoprotectprivacyofvehiclesfrombeingpossiblytracked.Obviously,theprivacyprotectionmustbescalablebecauseofthehighmobilityandlargepopulationofvehicles.Inthiswork,wetakeanon-trivialsteptowardsprotectingprivacyofvehicles.Asprivacydrawspublicconcerns,wefirstlypresentprivacyimplicationsofoperationalchallengesfromthepublicpolicyperspective.Additionally,weenvisionvehicularnetworksasgeographicallypartitionedsubnetworks(cells).Eachsubnetworkmaintainsalistofpseudonyms.Eachpseudonymincludesthecell’sgeographicidandarandomnumberashostid.Beforestartingcommunication,vehiclesneedtorequestapseudonymondemandfrompseudonymserver.Inordertoimproveutilizationofpseudonyms,weaddressastochasticmodelwithtime-varyingarrivalanddeparturerates.Ourmaincontributionincludes:1)proposingascalableandeffectivealgorithmtoprotectprivacy;2)providinganalyticalresultsofprobability,varianceandexpectednumberofrequestsonpseudonymservers.Theempiricalresultsconfirmtheaccuracyofouranalyticalpredictions.
简介:Theperformanceofmassivemultiple-inputmultiple-output(MIMO)systemislimitedbypilotcontamination.Toreducethepilotcontamination,uplinkanddownlinkprecodingalgorithmsareputforwardbasedoninterferencealignmentcriterion.Intheuplinkreceivingprocessing,thetargetfunctionalignsthepilotcontaminationandtheinterferencesignalstothesamenullspaceandacquiresthemaximalspacedegreeofthedesiredsignals.Theuplinkreceivingprecodingmatrixissolvedonmaximalsignaltointerferenceplusnoiseratio(SINR)criterionconsideringtheimpactofthepilotcontaminationonchannelestimations.Theuplinkreceivingprecodingmatrixisusedasthedownlinktransmittingprecodingmatrix.Exploitingthechannelreciprocity,itisprovedthat,iftheuplinkreceivingprecodingmatrixachievesmaximalSINR,theidenticalprecodingmatrixcanbeusedinthedownlinktransmissionandacquiresmaximalsignaltoleakageplusnoiseratio(SLNR).Simulationsshowthatthespectrumefficiencyoftheproposedalgorithmcanreachabout1.5timeshigherthanthatofpopularmatchedfiltering(MF)precodingalgorithm,andabout1.1timeshigherthanmulti-cellminimummeansquareerror(MMSE)precodingalgorithm.Theperformanceoftheproposedalgorithmcanbeimprovedapproximatelylinearlywiththeincreasingofthenumberofantennas.
简介:Quantumalgorithmsbringgreatchallengestoclassicalpublickeycryptosystems,whichmakescryptosystemsbasedonnon-commutativealgebraicsystemshoptopic.Thebraidgroups,whicharenon-commutative,haveattractedmuchattentionasanewplatformforconstructingquantumattack-resistantcryptosystems.Aringsignatureschemeisproposedbasedonthedifficultyoftherootextractionproblemoverbraidgroups,whichcanresistexistentialforgeryagainsttheadaptivelycho-sen-messageattackundertherandomoraclemodel.
简介:Thispaperpresentsfuzzy-baseddesignforthecontrolofoverheadcrane.Insteadofanalyzingthecomplexnonlinearcranesystem,theproposedapproachusessimplebuteffectivewaytocontrolthecrane.Therearetwinfuzzycontrollerswhichdealwiththefeedbackinformation,thepositionoftrolleycraneandtheswingangleofload,tosuppresstheswayandacceleratethespeedwhenthecranetransportstheheavyload.Thisapproachsimplifiesthedesigningprocedureofcranecontroller;besides,thetwincontrollermethodreducestherulenumberwhenfulfillingthefuzzysystem.Finally,experimentalresultsthroughthecranemodeldemonstratetheeffectivenessofthescheme.
简介:在这篇文章,一个Grassmannianprecoding多用户多重输入多重产量(MU-MIMO)为downlink传播的计划被建议。建议MU-MIMO计划将表现安排并且precoding同时在库驻扎,增加获得多用户差异获得和precoding,最大化系统能力。precoding方法与Grassmannianprecoding有关,它扩大点对点的单个用户的Grassmannianprecoding到point-to-multipoint多用户Grassmannianprecoding。它比单身的用户MIMO(SU-MIMO)系统提供进一步重要的系统能力改进并且也超过块diagonalization(BD)在一样的模拟环境下面的算法。
简介:Takingtheadvantageoftheliftingscheme'scharactersthatcanbuildwavelettransformsfortransformingfromintegertointegerandthequalityofthereconstructingimageisindependentofthetopologywayadoptedbytheboundary,animagefusionalgorithmbasedonliftingschemeisproposed.Thispaperdiscussesthefundamentaltheoryofliftingschemefirstlyandthenaftertakingtransformanalysisaccordingtoakindofimagesthatneedtobeconfused.
简介:Aquantitativeschemeisputforwardinourworkofforecastingthestormrainfalloftyphoonsforspecificsites.Usingtheinitialparameters,weathersituationsandphysicalquantitiesaswellasnumericalweatherpredictionproducts,theschemeconstructsmultivariate,objectiveandsimilaritycriteriaforenvironmentalfactorsforthetimebetweenthecurrentandforthcomingmomentwithinthedomainofforecast.Throughdefininganon-linearsimilarityindex,thisworkpresentsacomprehensiveassessmentofthesimilaritybetweenhistoricalsamplesoftyphoonsandthosebeingforecastintermsofcontinuousdynamicstatesunderthemultivariatecriteriainordertoidentifysimilarsamples.Thehistoricalrainfallrecordsofthesimilarsamplesareusedtorunweightedsummarizationofthesimilarityindextodeterminesite-specificandquantitativeforecastsoffuturetyphoonrainfall.Samplesresemblingthetyphoonbeingforecastareselectedbydefininganon-linearsimilarityindexcomposedofmultiplecriteria.Trialtestshavedemonstratedthatthisschemehaspositivepredictionskill.
简介:MM5,它是PSU/NCAR中央放大非静水力学的有限区域的模型,并且它毗连当模特儿的系统在这篇论文被使用。由使用二假数据吸收的台风的一个最佳的起始的条件策划的作者产生的背景回答的拿的T106分析数据,和某数字模仿试验的行为。No.9608typhoon(葛洛丽亚)的结果证明最佳的起始的地有一些戏剧的改进,例如台风中心,更弱的台风发行量和台风的不完全的内部结构的不精密的位置,它被数据的缺乏在海上引起。一些改进在轨道预报被做了。通过几个比较实验,BDAscheme优化的初始化比GFDL计划和它的台风路经预报更好被发现更合理。