简介:Onthehypothesisthattheturbulentflowispracticallynotaffectedincharacterbypulsationoftheflow,theformulaforsoundpressurelevelofpulsedjetnoiseisobtainedin90°directionand1meterawayfromthenozzle.Thesteadyjetnoiseis,then,aspecialcasewhenthepulsatingfrequencyiszero.Theresultsagreewellwithexperiments.
简介:Onthebasisofspectrummomentdescriptionofasignal,evolutionaryvectorisdeveopedtodescribeslowlytime-varyingnoiseprocesses.Itdescribesthemaintime-varyingpropertiesofasignal.Applicationstoaircraftflying-overnoisearepresented.
简介:Fromtheevolutionaryvectordeacriptionofslowlysime-varyingnoiseprocess,ameasurefornon-stationarityisdeveloped.Itincludesboththenon-stationaritiesofpowerandofspectrumshape.Asasingleparameter,itisacomparablequantityfordifferentprocesses.Applicationtotheanalysisofprecisegearboxisprescnted.