简介：Asamanifestationoftheunderlyingphysicalnature,quailtumoscillationswiththeappliedmagneticfield(B)areoneofthemostimportanttopicsincondensedmatterphysics.Theresearchhistorycanbetrackedto1930whenLevShubnikovandW.J.deHaasobservedShubnikov-deHaas(SdH)oscillationsinthemagnetoresistance(MR)ofbismuthcrystals.Sincethen,researchershaveobservedquantumoscillationsindiversematerials,includingmetals,metalliccompounds,semimetals,semiconductorsandeveninsulators,aswellasinartificialmesoscopicmicrostructures.Nowadays,quantumoscillationdetectedbymagnetotransportinvestigationhasbeenapowerfultooltodetectthephysicalpropertiesinsolid-statesystems.

简介：ItisdifficulttodesignaplatewithwideattenuationzonesinlowfrequencyregionbasedonBraggscatteringmechanism.Aplatewithperiodicrhombusholesisoptimizedanddesigned.Basedonthefiniteelementmethodunderperiodicboundaryconditions,thein-planedispersioncurvesofperiodicallyperforatedplatearecalculatedviaCOMSOL.ThefrequencyresponsesofperiodicallyperforatedplateareinvestigatedviaANSYSsimulation.Theplateswithperiodicholesaresuspendedanddynamicallytestedundersinusoidalexcitations.Theresultsshowthataperiodicallyperforatedplatewithrhombusholeshaswiderattenuationzonesthanplateswithcircularandhexagonalholes.Materialpropertieshaveagreatinfluenceonattenuationzones:nitrile-butadienerubberandsiliconrubbercaneasilyobtainlow-frequencyzones,whileincreasingporositycreateslowerandwiderzones.Thewidthofattenuationzoneincreasesasthehorizontalangleoftherhombusholesincreases.Ananalysisoftheattenuationzones'generationmechanismshowsthattheplatewithperiodicholesexhibitscharacteristicsofBraggscatteringandlocalresonantphononiccrystal,indicatinganinherentrelationshipbetweentwotypesofmechanisms.Theoptimizedplatehasacompleteattenuationzonerangingfrom5281.76-8824.30Hz.Thevibrationsaresignificantlyreducedwhenthenumberofperiodsisnolessthantwo.Theattenuationrangeobtainedviathenumericalmethodisgenerallyconsistentwiththeexperiment.Theresearchshedslightonthenoiseinsulationplateandhasthepotentialtoimprovethesoundenvironmentinvariousapplicationsduetoitssimplemanufacturing.

简介：Parametricresonanceisoneofthemostimportantissuesinthestudyofdynamicalbehaviorofstructures.Inthispaper,dynamicinstabilityofamoderatelythickrectangularplateonanelasticfoundationisinvestigatedinthecaseofparametricandexternalresonancesduetoperiodicpassageofmovingmasses.Thegoverningcoupledpartialdifferentialequations(PDEs)ofthesystem,withconsiderationofthefirst-ordersheardeformationtheory(FSDT)orMindlinplatetheory,arepresentedandtheyarereducedtoasetofordinarydifferentialequations(ODEs)withtime-dependentcoefficientsusingtheGalerkinprocedure.Allinertialcomponentsofthemovingmassesareadoptedinthedynamicalformulation.Instabilitysurveyiscarriedoutforthreedifferentloadingtrajectoriesconsiderablyinterestedinmanypracticalapplicationsoftheissue,i.e.rectilinear,diagonalandorbitingtrajectories.Inordertoanalyzetheresonanceconditions,theincrementalharmonicbalance(IHB)methodisintroducedtocalculateinstabilityboundaries,aswellasexternalresonancecurvesinparametersplane.Acomprehensivestudyisdonetoassesseffectsofthicknessratioandfoundationstiffnessontheresonanceconditions.Itisfoundthatanincreaseintheplate'sthicknessratioleadstoareductioninvaluesofcriticalparameters.Moreover,itisobservedthatincreasingthefoundationstiffnessmovestheinstabilityregionsandresonaneecurvestohigherfrequenciesofthemovingmassesandalsoleadstofurtherstabilityoftheparametricallyexcitedsystematlowerfrequencies.TimeresponsesimulationsdoneviaRunge-KuttamethodconfirmedtheresultspredictedbyIHBmethod.

简介：Highspatialfrequencylaserinducedperiodicsurfacestructures(HSFLs)onsiliconsubstratesareoftendevelopedonflatsurfacesatlowfluencesnearablationthresholdof0.1J/cm2,seldomonmicrostructuresormicrogroovesatrelativelyhigherfluencesabove1J/cm^2.ThisworkaimstoenrichthevarietyofHSFLs-containinghierarchicalmicrostructures,byfemtosecondlaser(pulseduration:457fs,wavelength:1045nm,andrepetitionrate:100kHz)inliquids(waterandacetone)atlaserfluenceof1.7J/cm^2.TheperiodofSi-HSFLsintherangeof110–200nmisindependentofthescanningspeeds(0.1,0.5,1and2mm/s),lineintervals(5,15and20μm)ofscanninglinesandscanningdirections(perpendicularorparalleltolightpolarizationdirection).ItisinterestinglyfoundthatbesidesnormalHSFLswhoseorientationsareperpendiculartothedirectionoflightpolarization,bothclockwiseoranticlockwiserandomlytiltedHSFLswithamaximaldeviationangleof50°ascomparedtothoseofnormalHSFLSsarefoundonthemicrostructureswithheightgradients.RamanspectraandSEMcharacterizationjointlyclarifythatsurfacemeltingandnanocapillarywavesplayimportantrolesintheformationofSi-HSFLs.ThefactthatnoHSFLsareproducedbylaserablationinairindicatesthatmoderatemeltingfacilitatedwithultrafastliquidcoolingisbeneficialfortheformationofHSFLsbyLALs.Onthebasisofourfindingsandpreviousreports,asynergisticformationmechanismforHSFLsathighfluencewasproposedanddiscussed,includingthermalmeltingwiththeconcomitanceofultrafastcoolinginliquids,transformationofthemoltenlayersintoripplesandnanotipsbysurfaceplasmonpolaritons(SPP)andsecond-harmonicgeneration(SHG),andmodulationofSi-HSFLsdirectionbybothnanocapillarywavesandthelocalizedelectricfieldcomingfromtheexcitedlargeSiparticles.