简介:Theaccuratedetectionofcooperativetargetsplaysakeyandfoundationalroleinunmannedaerialvehicle(UAV)landingautonomously.Thestandardmethodbasedonfixedthresholdistoosusceptibletobothilluminationvariationsandinterference.Toovercomeissuesabove,arobustdetectionalgorithmwithtripleconstraintsforcooperativetargetsbasedonspectralresidual(TCSR)isproposed.Firstly,bydesigninganasymmetriccooperativetarget,whichcomprisesredbackground,greenHandtriangletarget,thecapturedoriginalimageisconvertedintoaLabcolorspace,whosesaliencymapisyieldedbyconstructingthespectralresidual.Then,thetripleconstraintsaredevelopedaccordingtothepriorknowledgeofthecooperativetarget.Finally,thesalientregioninsaliencymapisconsideredasthecooperativetarget,anditmeetsthetripleconstraints.ExperimentalresultsincomplexenvironmentsshowthattheproposedTCSRoutperformsthestandardmethodsinhigherdetectionaccuracyandlowerfalsealarmrate.
简介:ThestainlessFe-Mn-Sishapememoryalloy(SMA)coatingwaspreparedonthesurfaceofAISI304stainlesssteel.Theprincipalresidualstressmeasuredbythemechanicalhole-drillingmethodindicatesthattheFe-Mn-SiSMAcladdingspecimenpossessesalowerresidualstresscomparedwiththe304stainlesssteelcladdingspecimen.Themeanstressvaluesoftheformerandthelatteron10-mm-thicksubstrateare4.751MPaand7.399MPa,respectively.What’smore,theirdeformationvalueson2-mm-thicksubstrateareabout0°and15°,respectively.Meanwhile,thevariationtrendandthevalueoftheresidualstresssimulatedbytheANSYSfiniteelementsoftwareconsistwithexperimentalresults.TheX-raydiffraction(XRD)patternshowsε-martensiteexistsinFe-Mn-SiSMAcoating,whichverifiesthemechanismoflowresidualstress.That’stheγ→εmartensitephasetransformation,whichrelaxestheresidualstressofthespecimenandreducesitsdeformationinthelasercladdingprocessing.