简介：Single-gritgrindingofa2.5Dwovencompositewasinvestigatedbythefinite-elementmethod(FEM)usingaunit-cellmodel.Accordingtoourhypotheses,theaxisofthewarpyarnwasasinusoidalcurveandthecrosssectionoftheweftyarnwasshapedlikeabiconvexlens.AVUMATsubroutinewasusedtoconstructtheconstitutivemodelofthe2.5Dwovencomposite.ThegrindingprocessofthecompositewasanalyzedusinganFEMsimulationwiththeABAQUS/Explicitsoftware.Avalidationexperimentwasalsocarriedout.Thesimulationresultsshowedthatagrindingcrackwaswellsimulated.Furthermore,thejunctionsbetweenthewarpyarnandweftyarnwerefoundtobeseriouslydamagedandcrackswereobservedtoextendoutwardalongthewarpfiberduringgrinding,ingoodagreementwiththeexperimentalresults.Inaddition,thestrainofweftyarnswasobviouslygreaterthanthatofwarpyarnswhenthegrindingdirectionwasperpendiculartotheweftyarnsandparalleltotheaxisofthewarpyarns.Theseresultsdemonstratethatthemesostructurestronglyinfluencesthegrindingdamageinflictedonwovencomposites.

简介：Randomphasemasksplayakeyroleinopticalimageencryptionschemesbasedondoublerandomphasetechnique.Inthispaper,amixedchaoticmethodisproposed,whichcanefficientlysolvesomeweaknessesthatone-dimensional(1-D)singlechaoticmapsencountertogeneraterandomphasemasks.Basedonthechaoticrandomphasemasks,opticalimageencryptionanddecryptionarerealizedwithasingle-shotdigitalholographictechnique.Intheproposedencryptionscheme,theinitialvalueandparametersofmixedchaoticmapsserveassecretkeys,whichisconvenientforthekeymanagementandtransmission.Moreover,italsopossesseshighresistanceagainststatisticalattack,brute-forceattack,noiseattackandshearattack.Simulationresultsandsecurityanalysisverifythevalidityandsecurityoftheproposedencryptionscheme.

简介：针对“观察DNA和RNA在细胞中的分布”实验出现的问题，提出了改进方法：在染色过程中材料不进行盐酸水解，通过调整混合染液中吡罗红和甲基绿的比例，以达到最佳染色效果；选择火葱和分蘖洋葱的鳞叶表皮作为植物材料的实验效果更好。通过上述实验方法的改进，可以得到稳定的、可重复的理想结果。