简介：磨擦，一枚戒指有弹性地支持了的一个磁盘的阶段特征被调查并且过去常解释僵硬增加现象的机制。只要磨擦被维持，磁盘上的磁盘和旋转的团之间的平均阶段差别毫无疑问是不到蟺/2。当磨擦完成时，阶段差别快速来临到蟺。这行为独立于磨擦系统的物理参数。理论结果是与实验验证的品质上。关键词僵硬增加现象-阶段特征-磨擦转子这个工程被支持由在里面英国的皇家学会和中国(10672006)的国家自然科学基础的来交情。

简介：SomeofthemainprogressontheinvestigationofthemechanismofthewaveformationinexplosiveweldingattheInstituteofMechanicsissummarizedandotters’previousworksarere-viewed.OursystematicexperimentsandanalysisdonotsubstantiatethetheoryofwaveformationbasedonKarmanvortex-streetanalogyorHelmholtzinstability.Onthecontrary,theyshowthatmateri-alstrengthinsensitivetostrainrateplaysanimportantrole.Asimplehydro-plasticmodelispresentedtoexplainthemainfeaturesregardingtheinterracialwaveformationandtoestimatethemagnitudeofwavelength.Theresultisinbroadagreementwithexperiment.

简介：Amodifiedsnap-throughmechanismisusedinanelectromagneticenergyharvestertoimproveitseffectiveness.Itmainlycomprisesthreespringsthatarecon-figuredsothatthepotentialenergyofthesystemhastwostableequilibriumpoints.Inparticular,thesmallvibrationbehavioroftheharvesteraroundoneoftheequilibriumsisofinterest.Amulti-scalemethod(MSM)isusedtoanalyzethefrequencyresponsecurve.Twosnap-throughmechanismsareconsidered.Onehasbothhorizontalandverti-calsprings.Theotherhasonlyhorizontalsprings.Thefrequencyresponsecurvesofthesetwoclassesarecomparedunderthesameexcitationandelectricloadingconditions.Thelatterexhibitsmorebendingofthefrequencyresponsecurvethantheformerone.Theresultsarealsovalidatedbysomenumericalwork.TheaveragedpowersubjecttotheGaussianwhitenoiseiscalculatednumerically,andtheresultsdemonstratethatbi-stableenergyharvestingwithonlyhorizontalspringscanoutperformthemechanismwithbothhorizontalandverticalspringsforthesamedistancebetweentwoequilibriums.

简介：NumericalsimulationsandexperimentalresearcharebothcarriedouttoinvestigatethecontrolledeffectofspanwiseoscillatingLorentzforceonaturbulentchannelflow.ThevariationsofthestreaksandtheskinfrictiondragareobtainedthroughthePIVsystemandthedragmeasurementsystem,respectively.Theflowfieldinthenear-wallregionisshownthroughdirectnumericalsimulationsutilizingspectralmethod.Theexperimentalresultsareconsistentwiththenumericalsimulationresultsqualitatively,andboththeresultsindicatethatthestreaksaretiltedintothespanwisedirectionandthedragreductionutilizingspanwiseoscillatingLorentzforcescanberealized.Thenumericalsimulationresultsrevealmoredetailofthedragreductionmechanismwhichcanbeexplained,sincethespanwisevorticitygeneratedfromtheinteractionbetweentheinducedStokeslayerandintrinsicturbulentflowinthenear-wallregioncanmakethelongitudinalvorticestiltandoscillate,andleadstoturbulencesuppressionanddragreduction.

简介：Intermediatefilamentsareoneofthekeycomponentsofthecytoskeletonineukaryoticcells,andtheirmechanicalpropertiesarefoundtobeequallyimportantforphysiologicalfunctionanddisease.Whilethemechanicalpropertiesofsinglefulllengthfilamentshavebeenstudied,howthemechanicalpropertiesofcrosslinksaffectthemechanicalpropertyoftheintermediatefilamentnetworkisnotwellunderstood.Thispaperappliesamesoscopicmodeloftheintermediatenetworkwithvariedcrosslinkstrengthstoinvestigateitsfailuremechanismundertheextrememechanicalloading.Itfindsthatrelativelyweakercrosslinksleadtoamoreflawtolerantintermediatefilamentnetworkthatisalso23%strongerthantheonewithstrongcrosslinks.Thesefindingssuggestthatthemechanicalpropertiesofinterfacialcomponentsarecriticalforbioinspireddesignswhichprovideintriguingmechanicalproperties.

简介：Atheoreticalmodelingapproachaswellasanunsteadyanalyticalmethodisusedtostudyaerodynamiccharacteristicsofwingflappingwithasymmetricstroke-cyclesinconnectionwithanobliquestrokeplaneduringinsectforwardflight.Itisrevealedthattheaerodynamicasymmetrybetweenthedownstrokeandtheupstrokeduetostroke-asymmetricalflappingisakeytounderstandtheflowphysicsofgenerationandmodulationoftheliftandthethrust.Predictedresultsforexamplesofgivenkinematicsvalidatemorespecificallysomeviewpointsthatthewingliftismoreeasilyproducedwhentheforwardspeedishigherandthethrustisharder,andtheliftandthethrustaregeneratedmainlyduringdownstrokeandupstroke,respectively.Theeffectsofthreecontrollingparameters,i.e.theanglesoftiltedstrokeplane,thedifferentdownstrokedurationratios,andthedifferentanglesofattackinbothdown-andup-stroke,arefurtherdiscussed.Itisfoundthatlargerobliqueanglesofstrokeplanesgeneratelargerthrustbutsmallerlift;largerdownstrokedurationratiosleadtolargerthrust,whilemakinglittlechangeinliftandinputaerodynamicpower;andagain,asmallincreaseoftheangleofattackindownstrokeorupstrokemaycauseremarkablechangesinaerodynamicperformanceintherelevantstroke.

简介：Laboratoryexperimentswereconductedtostudythespallationbehaviourofthermalbarriercoatings(TBCs)onaero-engineturbinebladesmanufacturedbytheelectron-beamphysicalvapourdepositiontechnique(EB-PVD).Intactbladeswereheatedattemperature1135°Cinafurnaceforcertaintimeandthencooledtotheroomtemperatureinthelaboratorycondition.Itwasfoundthatnospallationoccurredduringcooling,butspallationhappenedatconstantroomtemperatureaftercooling.Thespallationmechanismisstudiedbyusingthemechanicalmodeldeveloped(Harvey2017andWang2017),whicharebasedonthehypothesisofpocketsofenergyconcentration(PECs).Someobservationsofthespallationbehaviourarewellpredictedbythemodel.

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简介：Insulatorsonhigh-voltageUansmissionlinesarealmosttheonlyman-madestructuresontheEarth'ssurfaceintendedforlong-termoperationunderstrongelectricfields.AftersamplesofnaturalcontaminantparticleswerecollectedfrominsulatorsurfacesinChina,itwasfoundthattheparticlediameterdistribution(PDD)wasmainlyconcentratedinthe5-50μmrange.Toanalyzethestatisticalcharacteristicsoftheseparticles,thisworkstudiesthephysicalprocessesofparticlecollisionandadhesionusingthetheoriesofhydrodynamicsandcollisiondynamics.Thephysicalmodelconsiderscouplingofthefluidfieldandtheelectricfield,introducesanadhesioncriterion,andestablishesaparticleandsurfacecollisionmodel.Theeffectsofrelativehumidity,windspeed,aerodynamicshape,electricfieldtype,andelectricfieldstrengthonparticleadhesionwereanalyzed.Theresultsshowthattherelativehumidityandwindspeedhaveverysignificanteffectsandtheinfluencesoftheelectricfieldtypeandtheelectricfieldstrengthareobvious,buttheinfluenceoftheaerodynamicshapeisrelativelyweak.Thesimulationresultssupportthestatisticalcharacteristicsdeterminedinthiswork.Thephysicalmodelestablishedhereprovidesreferencevaluesforstudyoftheadhesioncharacteristicsofparticlesonsurfacesunderelectricfields.

简介：AmodelofcrosslinkerunbindingisimplementedinahighlycoarsegrainedgranularmodelofF-actincytoskeleton.WeemploythisspecificgranularmodeltostudythemechanismsofthecompressiveresponsesofF-actinnetworks.ItisfoundthatthecompressiveresponseofF-actincytoskeletonhasdependencyonthestrainrate.TheevolutionofdeformationenergyinthenetworkindicatesthatcrosslinkerunbindingeventscaninducetheremodellingofF-actincytoskeletoninresponsetoexternalloadings.TheinternalstressinF-actincytoskeletoncanefficientlydissipatewiththehelpofcrosslinkerunbinding,whichcouldleadtothespontaneousrelaxationoflivingcells.

简介：Toanalyzethedynamicmechanismofunusualactivitiesofthesubtropicalhigh,thespace-timevaribleseparationofthepartialdifferentialvortexequationsiscarriedoutwithGalerkinmethodsbasedontheheatforceandthewhirlmovementdissipationeffect.Aimingatthesubjectiveandman-madeconventionalmethodofchoiceinthespacebasisfunctions,weproposetocombinetheempiricalorthogonalfunction(EOF)analysiswiththegeneticalgorithmtoinversethespacebasisfunctionsfromtheactualsequenceoffields.Agroupoftrigonometricfunctionsarechosenasageneralizedspacebasisfunction.Withtheleast-squareserrorofthebasisfunctionandEOFtypicalfields,andwiththecompleteorthogonalityofbasisfunctions,wecangetthedual-boundfunction.Ageneticalgorithmisthenintroducedtocarryoutsurfacefittingandcoeffcientoptimizationofthebasisfunction.Asaresult,theobjectiveandreasonableconstantdifferentialequationofthesubtropicalhighisobtainedbyinversion.Finally,basedontheobtainednonlineardynamicsmodel,thedynamicbehaviorandmechanismofthesubtropicalhighisanalyzedanddiscussedundertheinfluenceofheatforce.Wefindthatsolarradiationandzonaldifferencesinlandandseaareimportantfactorsimpactingthepotentialfieldandflowfieldchangesofthesubtropicalareas.Thesefactorsleadtostrengthchangesofthesubtropicalhighandmedium-termadvance/retreatactivities.Theformerisagradualchange,whilethelattershowsmorebreakcharacteristics.Meaningfulresultsareobtainedintheanalysis.

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简介：Theseeminglycontradictoryunderstandingsoftheinitialcrushstressofcellularmaterialsunderdynamicloadingsexistintheliterature,andacomprehensiveanalysisofthisissueiscarriedoutwithusingdirectinformationoflocalstressandstrain.Localstress/straincalculationmethodsareappliedtodeterminetheinitialcrushstressesandthestrainratesatinitialcrushfromacell-basedfiniteelementmodelofirregularhoneycombunderdynamicloadings.Theinitialcrushstressunderconstant-velocitycompressionisidenticaltothequasi-staticone,butlessthantheoneunderdirectimpact,i.e.theinitialcrushstressesunderdifferentdynamicloadingscouldbeverydifferenteventhoughthereisnostrain-rateeffectofmatrixmaterial.Apower-lawrelationbetweentheinitialcrushstressandthestrainrateisexploredtodescribethestrain-rateeffectontheinitialcrushstressofirregularhoneycombwhenthelocalstrainrateexceedsacriticalvalue,belowwhichthereisnostrain-rateeffectofirregularhoneycomb.Deformationmechanismsoftheinitialcrushbehaviorunderdynamicloadingsarealsoexplored.Thedeformationmodesoftheinitialcrushregioninthefrontofplasticcompactionwavearedifferentunderdifferentdynamicloadings.

简介：Octahedron-likeBaMoO4microcrystalsweresynthesizedbytheco-precipitationmethodatroomtemperatureandprocessedinmicrowave-hydrothermalat413Kfordifferenttimes(from30minto5h).ThesemicrocrystalswereanalyzedbyX-raydiffraction(XRD),field-emissiongunscanningelectronmicroscopy(FEG-SEM)andtransmissionelectronmicroscopy(TEM).XRDpatternsshowedthatthismaterialpresentsatetragonalstructurewithoutthepresenceofdeleteriousphases.FEG-SEMandTEMmicrographsrevealedthattheBaMoO4microcrystalspresentanoctahedron-likemorphologywithagglomeratenatureandpoly-disperseparticlesizedistribution.Thesemicrographsalsoindicatedthatthemicrocrystalsgrowalongthe[001]direction.Theobservedcrystallographicplanesinthesestructuresweremodeledcomputationallyandacrystalgrowthmodelwasproposedinordertoexplainthemorphologicalchangesasafunctionofprocessingtime.

简介：Basedonourpreviouswork,self-excitedvibrationofamulti-degree-of-freedomsystemcausedbydryfrictionbetweentwoelasticstructuresisinvestigatedusingtheChineseculturalrelicdragonwashbasinasanexample.Somenewcharacteristicsoftheself-excitedvibrationinthiskindofsystemarefound.Theconditionsunderwhichself-excitedvibrationoccursatlow-orderorhigh-ordermodesarediscussed.Effectsofchangesinparametersofthesystemontheself-excitedvibrationareanalyzed.ThevibrationmechanismofthewaterdropletsspurtingphenomenonoftheChineseculturalrelicdragonwashbasinisfurtherexplained.Thisinvestigationpresentsanewideaformodelingtheself-excitedvibrationcausedbydryfrictioninteractionbetweentwoelasticstructures.