简介：

简介：

简介：

简介：Thispapergivesthedirectivityfunctionofasectoralmul-ti-elementcylinderarray,analyzeitsphasefactor,explainindetailthesideloberejectionbyselectingthenumberofelements,bafflingandamplitudeweighting.Theyareparticularlyusefulfordirectionaltrackingofacousticalsignalandtargetlocating.

简介：Twocoupled-modemethods,namelyDGMCM(Direct-Global-MatrixCoupledModeMethod)andCCMM(ConsistentCoupled-ModeMethod),areanalyzedandcompared.First,bothofthesetwomethodsprovidetwo-waysolutions,andhencetheyareaccuratemodels.Second、theseriesoflocalverticalmodesinDGMCMconvergesasfastasthatinCCMM,whereasDGMCMhasamoretolerablerequirementofthenumberofsegmentsthanCCMM.Third,thesetwomodelsobtainthefieldsolutionbysolvingthecoupled-modesystemwithdifferentcoefficientmatrices,inwhichthecomputationaletfortfortherequiredparametersisalmostthesame.Finally,DGMCMcanhandlesomeproblemswhicharedifficultforCCMM,suchasinawaveguidewitharoughbottom,alinesourcelocatedrightontopofaslopingbottom,orinthepresenceofmultiplesources.InDGMCM,closed-formexpressionsforcouplingmatricesinatwo-layerwaveguidearegiven.Inaddition.theformulationfortheline-sourceprobleminplanegeometryisderivedtoupdateCCMM.