简介:Theeffectofsystemmismatchesonanadaptivelinearconstrainedgeneralizedsidelobecanceller(LC-GSC)isdiscussedinthispaper.Basedonthearraygainindex,twoclassicsystemmismatches,thedirectionofarrival(DOA)mismatchandthemismatchesarisingfromarraydisturbance,arestudied,respectively.Toobtaintheeffectivemethodsforcompensatingforthesystemmismatches,weanalyzetheperformanceoftheimprovedLC-GSCwiththediagonalloadingandadditionalconstraints(suchasthedirectionalconstraintsandderivativeconstraints).Thecomputersimulationsshowthatthetechniquesofdiagonalloadingandadditionalconstraintscaneffectivelycompensateforthesystemmismatches.Thelossofarraygainscanbecontrolledwithin3dBinthepresenceof20%ofarraydisturbancesorDOAmismatchwhenthesignal-to-noiseratioislessthan10dB.Theanalysisillustratesthattheproposedcompensationmethodsarevalidandfeasible.
简介:Thispaperpresentsaschemetoidentifyandcompensatethetimingmismatchesbetweentwochannelsfortimeinterleavedphotonicanalog-to-digitalconverters(TIPADCs).Theimpactofelectro-opticsamplingisremovedbypreprocessingfirstly.ThenacalibrationmethodcombiningchoppingprocessingandaHilberttransformisproposedtoidentifythetimingmismatches,whichcanbefurthercompensatedbyusingvariousmaturecompensationalgorithms.Theprincipleoftheproposedmethodisderivedtheoretically.Theperformanceoftheschemeisanalyzedbysimulation.Theresultsshowthattheharmonicinducedbytimingmismatchescanbesuppressedbymorethan30dBusingtheproposedcorrectionscheme.
简介:Inthispaper,6mmthick2219-T6aluminumalloywasjoinedbymeansofvariablepolaritytungsten-arcwelding(VP-TIG)andtheinfluenceofgradientmismatchesonVP-TIGjointsisinvestigated.Theaveragetensilestrengthofthejointsreduces32%,53%and59%,whenthemismatchofthejointwas0.635mm,1.44mm,1.83mm,respectively.Incompletepenetration,additionalbendingmoment(Ma)anddecreaseofeffectiveloadregionareaareconsideredtoexplainthisphenomenon.Thefracturelocationoftensilespecimensoccurredattheweldzone(WZ)closetopartialmeltzone(PMZ),correspondingtoasharpdeclineofmicrohardnessfromPMZtoWZ.Theoriginalpositionoffractureisfoundatweldtoe,whereincompletepenetrationformsduetotheintroductionofgradientmismatches.