简介:Anovelefficienttrackinitiationmethodisproposedfortheharshunderwatertargettrackingenvironment(heavyclutterandlargemeasurementerrors):tracksplitting,evaluating,pruningandmergingmethod(TSEPM).Trackinitiationdemandsthatthemethodshoulddeterminetheexistenceandinitialstateofatargetquicklyandcorrectly.Heavyclutterandlargemeasurementerrorscertainlyposeadditionaldifficultiesandchallenges,whichdeteriorateandcomplicatethetrackinitiationintheharshunderwatertargettrackingenvironment.Therearethreeprimaryshortcomingsforthecurrenttrackinitiationmethodstoinitializeatarget:(a)theycannoteliminatetheturbulencesofcluttereffectively;(b)theremaybeahighfalsealarmprobabilityandlowdetectionprobabilityofatrack;(c)theycannotestimatetheinitialstateforanewconfirmedtrackcorrectly.Basedonthemultiplehypothesestrackingprincipleandmodifiedlogic-basedtrackinitiationmethod,inordertoincreasethedetectionprobabilityofatrack,tracksplittingcreatesalargenumberoftrackswhichincludethetruetrackoriginatedfromthetarget.Andinordertodecreasethefalsealarmprobability,basedontheevaluationmechanism,trackpruningandtrackmergingareproposedtoreducethefalsetracks.TSEPMmethodcandealwiththetrackinitiationproblemsderivedfromheavyclutterandlargemeasurementerrors,determinethetarget’sexistenceandestimateitsinitialstatewiththeleastsquaresmethod.What'smore,ourmethodisfullyautomaticanddoesnotrequireanykindmanualinputforinitializingandtuninganyparameter.Simulationresultsindicatethatournewmethodimprovessignificantlytheperformanceofthetrackinitiationintheharshunderwatertargettrackingenvironment.
简介:Ahigher-orderboundaryelementmethod(HOBEM)forsimulatingthefullynonlinearregularwavepropagationanddiffractionaroundafixedverticalcircularcylinderisinvestigated.Thedomaindecompositionmethodwithcontinuityconditionsenforcedontheinterfacesbetweentheadjacentsub-domainsisimplementedforreducingthecomputationalcost.Byadjustingthealgorithmofiterativeprocedureontheinterfaces,fourtypesofcouplingstrategiesareestablished,thatis,Dirchlet/Dirchlet-Neumman/Neumman(D/D-N/N),Dirchlet-Neumman(D-N),Neumman-Dirchlet(N-D)andMixedDirchlet-Neumman/Neumman-Dirchlet(MixedD-N/N-D).Numericalsimulationsindicatethatthedomaindecompositionmethodscanprovideaccurateresultscomparedwiththatofthesingledomainmethod.Accordingtothecomparisonsofcomputationalefficiency,theD/D-N/Ncouplingstrategyisrecommendedforthewavepropagationproblem.Asforthewave-bodyinteractionproblem,theMixedD-N/N-Dcouplingstrategycanobtainthehighestcomputationalefficiency.
简介:Thispaperfirstproposesanewapproachforpredictingthenonlinearwavetroughdistributionsbyutilizingatransformedlinearsimulationmethod.ThelinearsimulationmethodistransformedbasedonaHermitetransformationmodelwherethetransformationischosentobeamonotoniccubicpolynomialandcalibratedsuchthatthefirstfourmomentsofthetransformedmodelmatchthemomentsofthetrueprocess.TheproposednewapproachisappliedforcalculatingthewavetroughdistributionsofanonlinearseastatewiththesurfaceelevationdatameasuredatthecoastofYuraintheJapanSea,anditsaccuracyandefficiencyareconvincinglyvalidatedbycomparisonswiththeresultsfromtwotheoreticaldistributionmodels,fromalinearsimulationmodelandasecondordernonlinearsimulationmodel.Finally,itisfurtherdemonstratedinthispaperthatthenewapproachcanbeappliedtoallthesituationscharacterizedbysimilarnondimensionalspectrum.