简介：Theviscousflowfieldaroundtwo-dimensionalflapping(heavingandpitching)foilswasnumericallycomputed.Thestructuralcharacteristicsofcaudalvorticeswereinvestigatedandthecontourcurvesatdifferentphaseangleswereobtained.Therelationshipsbetweenthestructuralcharacteristicsofthevorticesandtheforceactingonthefoilandbetweenthewidthsofthecaudalvortexstreetandofthecaudalflowfieldwereanalyzed.Amethodtodeterminethesheddingfrequencyofthevorticeswasproposed.

简介：Bionicnon-smoothsurfaces(BNSS)canreducedrag.Muchattentionhasbeenpaidtothemechanismofshearstressreductionbyriblets.Themechanismofpressureforcereductionbybionicnon-smoothsurfacesonbodiesofrevolutionhasnotbeenwellinvestigated.InthisworkCFDsimulationhasrevealedthemechanismofdragreductionbyBNSS,whichmayworkinthreeways.First,BNSSonbodiesofrevolutionmaylowerthesurfacevelocityofthemedium,whichpreventsthesuddenspeedupofaironthecrosssection.Sothebottompressureofthemodelwouldnotbedisturbedsharply,resultinginlessenergylossanddragreduction.Second,themagnitudeofvorticityinducedbythebionicmodelbecomessmallerbecause,duetothesculpturing,thegrowthoftinyairbubblesisavoided.Thusthelargemomentofinertiainducedbylargeairbubbleisreduced.Thereductionofthevorticitycouldreducethedissipationoftheeddy.Sothepressureforcecouldalsobereduced.Third,thethicknessofthemomentumlayeronthemodelbecomeslesswhich,accordingtotherelationshipbetweenthedragcoefficientandthemomentumthickness,reducesdrag.

简介：Theheadmounteddisplay(HMD)iswidelyusedinvirtualrealitytechnology.IncommonHMD,however,thebinoculardisparityissettoanequalfixedvalueintheentirerangeofview.SuchHMDsystemshaveseveralshortcomingswhenusedforwideviews.Inthisstudy,inordertorealizeanaturalstereosensationofHMDwithwideview,wemeasurethecharacteristicsofbinocularstereoperceptionandbinocularlightperception.Resultsshowthatboththestereoacuityandlightsensitivitydecreaseastheretina'seccentricityincreasesfromfoveatoperiphery.However,thedecreaseofthestereoacuityismorerapidthanthatofthelightsensitivity.Theseresultssuggestthatthebinoculardisparityattheperipheralfieldshouldbesmall,otherwisedoubleimageswouldbeobservedinsteadofastereoview.Basedontheresultswedeveloparelativebinocularstereoacuitymodelwhichcanbeapplied{orthedesignofHMDsystemswithwideview.