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简介：Thisreportdescribesanewmethod,theself-searchingmethod,tofindeigenraysinanoceanwherethereisathree-dimensionalsoundspeedperturbationblobonauniformsoundspeedbackground.Comparedwiththetraditionalshootingmethod,thismethodcanreducethenumberofraycalcula-tionsbyabouttwoordersofmagnitude,andaneigenraycanbefoundbycom-puterprogramwithoutmanualintervention.

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简介：Thestudyofwaveguideinvariantinunderwateracousticsisoneofattractedtopicsinrecent30years.Theinterferencesofdirectwaveandreflectwavefromseasurfaceandseabottomofunderwatertargetradiatednoiseinherenttheinformationoftargetdistance.Extractionofthesedistanceinformationwillprovideapossiblenewwayinpassiverangingforunderwatertarget.ThetheoreticalanalysisandtheresultsofatseaexperimentsshowthattheLOFAR(LowFrequencyAnalysisRecord)figureinherentlycontainstherangeandmovinginformationofpassiveacousticsources,eveninthesituationthatthereceiverisonlyonesinglehydrophone.Thetheoreticalanalysisofextractionoftargetdistanceinformationbyusingwaveguideinvariantispresentedinthispaper.Itisshownthat,basedontheinterferencestriationpatternoftarget,thehydrophonearraysystemispossibletoextractthedistanceinformationwithquitehigharraygain.Althoughthemathematicalconstrainconditionsinforminginterferencestriationpatternaredifferentforindividualarrayelement,butitisprovedthatthedifferencesoftimedelaysbetweenarrayelementscanbeusedincompensationofbeamforming.Thetheoreticalanalysis,systemsimulationandsomeresultsofatseaexperimentshowanewwayinpassiverangingandtargetrecognition.

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