学科分类
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4 个结果
  • 简介:Withtheincreaseinminingdepth,mineheatharmhasappearedtobemoreprominent.Themineheatharmcouldberesolvedorreducedbyicerefrigeration.Thus,icetransportationthroughpipelinebecomesacriticalproblem;typicallyflowresistanceoccursintheelbow.Inthepresentstudy,accordingtotheanalysisofthesurfacemorphologyoffishscale,abiomimeticfunctionalsurfacestructurefortheinteriorwallofelbowisdesigned.Basedonthetheoryofliquid-solidtwophaseflow,aCFDnumericalsimulationofice-watermixtureflowingthroughtheelbowiscarriedoutusingfiniteelementmethod.Conventionalexperimentsofpressuredropandflowresistanceforbothbionicandcommonelbowsareconductedtotesttheeffectofthebionicelbowonflowresistancereduction.Itisfoundthatwiththeincreaseintheicemassfractionintheice-watermixture,theeffectofbionicelbowonresistancereductionbecomesmoreobvious.

  • 标签: BIONIC ELBOW two phase FLOW ICE
  • 简介:Thefracturetoughnessofhardbiomaterials,suchasnacre,bovinehoofwallandbeetlecuticle,isassociatedwithfibrousorlamellarstructuresthatdeflectorstopgrowingcracks.Theirhardnessandreducedmodulusweremeasuredbyusingananoindenterinthispaper.Micro/nanoscalecracksweregeneratedbynanoindentationusingaBerkovichtip.Nanoindentationofnacreandbovinehoofwallresultedinpile-uparoundtheindent.Itwasfoundthatthefracturetoughness(KC)ofbovinehoofwallisthemaximum,thesecondisnacre,andtheelytracuticleofdungbeetleistheleastone.

  • 标签: 生物材料 断裂韧度 纳米压入技术 仿生学
  • 简介:Thehumanfootisaverycomplexstructurecomprisingnumerousbones,muscles,ligamentsandsynovialjoints.Astheonlycomponentincontactwiththeground,thefootcomplexdeliversavarietyofbiomechanicalfunctionsduringhumanlocomotion,e.g.bodysupportandpropulsion,stabilitymaintenanceandimpactabsorption.Theseneedthehumanfoottoberigidanddampedtotransmitgroundreactionforcestotheupperbodyandmaintainbodystability,andalsotobecompliantandresilienttomoderateriskyimpactsandsaveenergy.Howdoesthehumanfootachievetheseapparentconflictingfunctions?Inthisstudy,weproposeaphase-dependenthypothesisfortheoveralllocomotorfunctionsofthehumanfootcomplexbasedonin-vivomeasurementsofhumannaturalgaitandsimulationresultsofamathematicalfootmodel.Wepropsethatfootfunctionsarehighlydependentongaitphase,whichisamajorcharacteristicsofhumanlocomotion.Inearlystancejustafterheelstrike,thefootmainlyworksasashockabsorberbymoderatinghighimpactsusingtheviscouselasticheelpadinbothverticalandhorizontaldirections.Inmid-stancephase(~80%ofstancephase),thefootcomplexcanbeconsideredasaspringyrocker,reservingexternalmechanicalworkusingthefootarchwhilstmovinggroundcontactpointforwardalongacurvedpathtomaintainbodystability.Inlatestanceafterheeloff,thefootcomplexmainlyservesasaforcemodulatorlikeagearbox,modulatingeffectivemechanicaladvantagesofankleplantiflexormusclesusingmetatarsal-phalangealjoints.Asoundunderstandingofhowdiversefunctionsareimplementedinasimplefootsegmentduringhumanlocomotionmightbeusefultogaininsightintotheoverallfootlocomotorfunctionsandhencetofacilitateclinicaldiagnosis,rehabilitationproductdesignandhumanoidrobotdevelopment.

  • 标签: 生物力学 人脚 运动模式 减震器
  • 简介:Theobjectiveofthisstudyistoinvestigatethebiomechanicalfunctionsofthehumanankle-tootcomplexduringthestancephaseofwalking.Thethree-dimensional(3D)gaitmeasurementwasconductedbyusinga3Dinfraredmulti-camerasystemandaforceplatearraytorecordtheGroundReactionForces(GRF)andsegmentalmotionssimultaneously.Theankle-footcomplexwasmodelledasafour-segmentsystem,connectedbythreejoints:talocruraljoint,sub-talarjointandmetatarsophalangealjoint.Thesubject-specificjointorientationsandlocationsweredeterminedusingafunctionaljointmethodbasedontheparticleswarmoptimisationalgorithm.TheGRFmomentarmsandjointmomentsactingaroundthetalocruralandsub-talarjointswerecalculatedovertheentirestancephase.Theestimatedtalocruralandsub-talarjointlocationsshownoticeableobliquity.Thekinematicandkineticresultsstronglysuggestthatthehumanankle-footcomplexworksasamechanicalmechanismwithtwodifferentconfigurationsinstancephaseofwalking.TheseleadtoasignificantdecreaseintheGRFmomentarmstherebyincreasingtheeffectivemechanicaladvantagesoftheankleplantarflexormuscles.Thisreconfigurablemechanismenhancesmuscleeffectivenessduringlocomotionbymodulatingthegearratiooftheankleplantarflexormusclesinstance.Thisstudyalsorevealsmanyfactorsmaycontributetothelocomotorfunctionofthehumanankle-footcomplex,whichincludenotonlyitsre-configurablestructure,butalsoitsobliquelyarrangedjoints,thecharacteristicheel-to-toeCentreofPressure(COP)motionandalsothemediallyactingGRFpattern.Althoughthehumanankle-footstructureisimmenselycomplex,itseemsthatitsconfigurationandeachconstitutivecomponentarewelltunedtomaximiselocomotorefficiencyandalsotominimiseriskofinjury.Thisresultwouldadvanceourunderstandingofthelocomotorfunctionoftheankle-footcomplex,andalsotheintrinsicdesignoftheankle-footmusculoskeletalstructure.Moreover,this

  • 标签: ANKLE FOOT talocrural JOINT sub-talar JOINT