简介：TheevaluationofcreepdamagesofCr-Mo-Vsteelusedinthegasturbineofpowerplanthasbeencarriedoutusingtheline-focus-beam(LFB)acousticmicroscopy.Thevelocityofleakysurfaceacousticwave(LSAW)propagatednearthespecimensurfacewasusedforthequantitativeevaluations,whichwasmeasuredbyLFBacousticmicroscopyusingthev(z)curveanalysismethod.IthasbeenshownthatwiththeincreaseofcreepdamagefractionofmetalmaterialtheLSAWvelocitydecreasesobviously,whichsuggeststhepossibilityofnondestructiveandquantitativeevaluationsofcreeddamagesinmetalmaterialsbyacousticmicroscopy.

简介：Amorerelaxedsufficientconditionfortheconvergenceoffiltered-XLMS(FXLMS)algorithmispresented.Itispointedoutthatifsomepositiverealconditionforsecondarypathtransferfunctionanditsestimatesissatisfiedwithinallthefrequencybands,FXLMSalgorithmconvergeswhateverthereferencesignalislike.Butiftheabovepositiverealconditionissatisfiedonlywithinsomefrequencybands,theconvergenceofFXLMSalgorithmisdependentonthedistributionofpowerspectraldensityofthereferencesignal,andtheconvergencestepsizeisdeterminedbythedistributionofsomespecificcorrelationmatrixeigenvalues.ApplyingtheconclusionabovetotheDelayedLMS(DLMS)algorithm,itisshownthatDLMSalgorithmwithsomeerroroftimedelayestimationconvergesincertaindiscretefrequencybands,andthewidthofwhicharedeterminedonlybythe"time-delayestimationerrorfrequency"whichisequaltoonefourthoftheinverseofestimatederrorofthetimedelay.