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简介:
简介:
简介:Thestressintensityfactor(SIF)isacriticalparameterassociatedwiththefracturebehaviourofmaterials.Inthispaper,weselectthedisplacementfunctionaroundacracktipastheshapefunctionofthedigitalimagecorrelation(DIC),whichmakesitpossibletodirectlycalculatetheSIFbythecorrelationscheme.Moreover,weuseanon-rectangularsubset,whichcanreducetheinfluenceofplasticdeformationandcrackwidthontheDICmeasurementaccuracy.WemeasuredtheSIFofamodeIcrackinasuper-hardaluminiumalloyspecimentoverifytheperformanceoftheproposedmethod.OurexperimentalresultsshowthataDICwithaspecificshapefunctioncanbeusedtoaccuratelyandefficientlycalculatetheSIF.Furthermore,wealsopresentapracticalapplicationofourproposedmethodfordeterminingtheSIF,crackpropagationangleandcracktipdisplacement.
简介:Randomphasemasksplayakeyroleinopticalimageencryptionschemesbasedondoublerandomphasetechnique.Inthispaper,amixedchaoticmethodisproposed,whichcanefficientlysolvesomeweaknessesthatone-dimensional(1-D)singlechaoticmapsencountertogeneraterandomphasemasks.Basedonthechaoticrandomphasemasks,opticalimageencryptionanddecryptionarerealizedwithasingle-shotdigitalholographictechnique.Intheproposedencryptionscheme,theinitialvalueandparametersofmixedchaoticmapsserveassecretkeys,whichisconvenientforthekeymanagementandtransmission.Moreover,italsopossesseshighresistanceagainststatisticalattack,brute-forceattack,noiseattackandshearattack.Simulationresultsandsecurityanalysisverifythevalidityandsecurityoftheproposedencryptionscheme.