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16 个结果
  • 简介:Itiswellknownthatsurfaceroughnesshasaveryimportanteffectonsuperhydrophobicity.TheWenzelandCassie-Baxtermodels,whichcorrespondtothehomogeneousandheterogeneouswettingrespectively,arecurrentlyprimaryinstructionsfordesigningsuperhydrophobicsurfaces.However,theparticulardropshapethatadropexhibitsmightdependonhowitisformed.Awaterdropcanoccupymultipleequilibriumstates,whichrelatetodifferentlocalminimalenergy.Insomecases,bothequilibriumstatescanevenco-existonasamesubstrate.Thustheapparentcontactanglesmayvaryandhavedifferentvalues.WediscusshowtheWenzelandCassie-Baxterequationsdeterminethehomogeneousandheterogeneouswettingtheoretically.Contactangleanalysisonhierarchicalsurfacestructureandcontactanglehysteresishasbeenputspecificattention.Inparticular,westudytheenergybarrieroftransitionfromCassie-BaxterstatetoWenzelstate,basedonexistingachievementbypreviousresearchers,todeterminethepossibilityofthetransitionandhowitcanbeinterpreted.Ithasbeendemonstratedthatsurfaceroughnessandgeometrywillinfluencetheenergyrequiredforadroptogetintoequilibrium,nomatteritishomogeneousorheterogeneouswetting.

  • 标签: SUPERHYDROPHOBIC surface contact ANGLE WETTING TRANSITION
  • 简介:Experimentalstudywasconductedforboundary-layersonasharp5°half-angleconeof400mmlengthatanglesofattack.ThemodelwastestedintheT-326hypersonicwindtunnel(ITAM)atfreestreamMachnumberM=5.95.Meanandfluctuationwallcharacteristicsoftheboundarylayeraremeasuredat0°2°3°and4°anglesofattackfordifferentstagnationpressures.PulsationmeasurementsarecarriedoutbymeansofALTPsensor.Pressureandtemperaturedistributionsalongthemodelareobtained,andtransitionbeginningandendlocationshavebeenfound.Boundarylayerstabilizationwiththeincreaseofangleofattackandthedecreaseofstagnationpressureisobserved.Highfrequencypulsationsinherenttohypersonicboundarylayer(secondmode)havebeendetected.

  • 标签: 可压缩边界层 角锥 实验 高超声速风洞 温度分布模型 特征测量
  • 简介:-Thevariationoftheamplitudeofwaveswithvaryingincidentangleswhenwavespropagatethroughatypicalapproachchannelisdiscussedbyanumericalcalculationmethod,theresultofwhichshowsthattheinfluenceofthechannelonwavepropagationisobvious.Whenthewavepropagationdirectionisincoincidencewiththechannelaxis,thewaveamplituderatiowilldecreasewiththeincreaseofpropagationdistance.Whentheincidentangleis15-30,thereappearsanareaoflargerwaveamplituderatioonthesideslopefacingthewaves,butattheanotherside,thewaveamplituderatioisgenerallysmall,indicatingthatthechannelhasashieldingeffect.Whenwavespropagateacrossthechannelperpendicularly,thewaveamplituderatiocanbecalculatedwiththeshallowwatercoefficient.

  • 标签: approach CHANNEL water wave VARYING INCIDENT
  • 简介:Thispaperaimstoinvestigatethehydrodynamicbehaviorofatensionlegplatform(TLP)whenthetendonconnectionanglesarevariedat90°,70°,50°,and30°.ThreedifferenttypesofloadingconditionsareappliedtotheTLP.Conditionsinclude100-yearhurricanestormperiod,regularwavesandnoloading.TheTLPdisplayedmajorresponseinthepitchdegreeoffreedom.Amaximumreductionof14%inpitchrotationisachievedwhen100-yearhurricanestormconditionsareappliedtotheTLP.Thisoccurredin0°loadingsat30°tendonconnectionangleascomparedto90°tendonconnectionangle.Reductioninpitchrotationisalsoachievedintheregularwaveloadings.Amaximumof9%inpitchrotationisachievedduring0°waveloadingat30°tendonconnectionangleascomparedto90°.Whenthetendonconnectionangleisreducedfrom90°to30°,thenaturalfrequencyoftheTLPincreasedbothinpitchandyawdegreesoffreedomby2.55%and2.40%,respectively.

  • 标签: TENDON CONNECTION IRREGULAR WAVES Regular WAVES
  • 简介:Whencharacterizingflowsinminiaturizedchannels,thedeterminationofthedynamiccontactangleisimportant.Bymeasuringthedynamiccontactangle,theflowpropertiesoftheflowingliquidandtheeffectofmaterialpropertiesontheflowcanbecharacterized.Amachinevisionbasedsystemtomeasurethecontactangleoffrontorrearmenisciofamovingliquidplugisdescribedinthisarticle.Inthisresearch,transparentflowchannelsfabricatedonthermoplasticpolymerandsealedwithanadhesivetapeareused.Thetransparencyofthechannelsenablesimagebasedmonitoringandmeasurementofflowvariables,includingthedynamiccontactangle.Itisshownthatthedynamicanglecanbemeasuredfromaliquidflowinachannelusingtheimagebasedmeasurementsystem.AnimageprocessingalgorithmhasbeendevelopedinaMATLAB?environment.Im-agesaretakenusingaCCDcameraandthechannelsareilluminatedusingacustommaderinglight.Twofittingmethods,acircleandtwoparabolas,areexperimentedandtheresultsarecomparedinthemeasurementofthedynamiccontactangles.

  • 标签: 数字图像处理 机器视觉 微观射流技术 图像测量 微通道
  • 简介:Afocusingtransformbasedminimumvariancemethod(FTMV)isproposedforestimatingtheazimuthanglesofwidebandsignals.TheestimationerrorofDirectionofArrival(DOA)inthetraditionalMinimumVariance(MV)methodduringthearraydirectionchangingwiththeshipcanbeeliminatedbyfocusingthesamplecovariancematricesinwidebandontoasinglenarrowband,andaccumulatingthebeamformeroutputsonazimuth.Then,theazimuthanglesofsignalscanbeestimatedaccurately.ExperimentalresultsshowthattheFTMVmethodismoreefficientandrobustthantheMVmethodinthiscase.

  • 标签: 声纳 信号处理 DOA 空间谱 常规聚束
  • 简介:我们在场为双向波浪方程移植的有效降噪策略。三种主导的人工制品类型被一个优化成像条件分析并且消除。我们讨论以前未解决的像横梁的人工制品,它可能被引起由向下从来源和单个地震射击的接收装置方面播送并且向上散布波浪跨关联。这人工制品有相对强壮的crosscorrelation,但是不从反射镜带有用信息。像横梁的人工制品广泛地存在在预先叠成像并且近似有象有用地震信号的一样的振幅。在大多数情况中,在图象的协调人工制品被方向性地宣传精力引起。基于wavefield坡度获得的繁殖角度,我们识别人工制品精力并且处于成像条件减去它的贡献。由这个过程,大多数人工制品能精确地被消除,包括直接波浪人工制品,散布人工制品,和beamlike人工制品。这个方法独立于wavefield增殖者并且如果需要,是容易的适应几乎所有当前的波浪方程迁居方法。当这个方法处理物理人工制品起源,很少损坏被引起到地震信号。过滤的额外的k域能另外提高叠的结果图象质量。这个方法在超级宽角度的单程的迁居成功并且我们能在另外的双向波浪方程迁居并且特别在反向的时间移植期望它的成功。

  • 标签: 波动方程偏移 传播 去噪 地震信号 成像条件 图像质量
  • 简介:Inordertoenhancethebearingcapacityofnon-circulargearpair,thenon-circulargearpairwithdoublegeneratinganglesisproposedbasedonthedesignideaofunsymmetricalgearwithdoublepressureangles.Thetoothprofileisdesignedbygeneratingcuttingtheory,thepurerollingmathematicmodelthatthecenterlineofunsymmetricalrackrollalongnon-circularpitchcurveisbuilt,thedigitalmodelofnon-circulargearwithdoublegeneratinganglesiscreatedthroughtheseconddevelopmentmethodofCADsoftware,andthenthedrivecharacteristicandtoothstrengthareanalyzed.Theresultsshowthatthedesignmethodfordoublegeneratinganglesnon-circulargearproposedinthispaperisfeasible,whichissignificanttoimprovethebearingcapacityofnon-circulargearpair.

  • 标签: 非圆齿轮副 设计方法 非对称齿轮 二次开发方法 承载能力 数字化模型
  • 简介:Weexperimentallydemonstratehighopticalqualityfactorsilicamicrodiskresonatorsonasiliconchipwithlargewedgeanglesbyreactiveionetching.For2-μm-thickmicroresonators,wehaveachievedwedgeanglesof59°,63°,70°,and79°withopticalqualityfactorsof2.4×10~7,8.1×10~6,5.9×10~6,and7.4×10~6,respectively,from~80μmdiametermicroresonatorsinthe1550nmwavelengthband.Also,for1-μm-thickmicroresonators,wehaveobtainedanopticalqualityfactorof7.3×10~6withawedgeangleof74°.

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  • 简介:Background:Investigationsofrunninggaitamongbarefootandpopulationshaverevealedadiversityoffootstrikebehaviors,withsomepreferentiallyemployingarearfootstrike(RFS)asthefoottouchesdownwhileothersemployamidfootstrike(MFS)orforefootstrike(FFS).Here,wereportfootstrikebehaviorandjointanglesamongtraditionalHadzahunter-gathererslivinginNorthernTanzania.Methods:Hadzaadults(n=26)andjuveniles(n=14)ranatarangeofspeeds(adults:mean3.4±0.7m/s,juveniles:mean3.2±0.5m/s)overanoutdoortrackwaywhilebeingrecordedviahigh-speeddigitalvideo.Footstriketype(RFS.MFS.orFFS)andhindlimbsegmentanglesatfootstrikewererecorded.Results:HadzamenpreferentiallyemployedMFS(86.7%ofmen),whileHadzawomenandjuvenilespreferentiallyemployedRFS(90.9%and85.7%ofwomenandjuveniles,respectively).NoFFSwasrecorded.Speed,thepresenceoffootwear(sandalsvs.barefoot),andtrialdurationhadnoeffectonfootstriketype.Conclusion:UnlikeotherhabituallybarefootpopulationswhichpreferFFSwhilerunning.HadzamenpreferredMFS.andHadzawomenandjuvenilespreferredRFS.SexandagedifferencesinfootstrikebehavioramongHadzaadultsmayreflectdifferencesinrunningexperience,withmenlearningtopreferMFSastheyaccumulatemorerunningexperience.

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  • 简介:在坚硬地在任意的角度连接的二个无限的盘子的角落接口的颤动精力传播被波浪途径学习以便调查堵住使用减少把波浪传播弄弯的飞机的质量的效果。二个本地坐标系统被介绍,暗示管理盘子的典型阻抗或堵住质量的相应比率的六个新非维的系数被介绍简化传播和思考系数的明确的表达。五件样品在experiment.Discussions被测试以插入损失基于在预言和实验之间的比较被执行。在角落接口堵住质量象“一个lowpass过滤器”一样行动,这被结束,为在某些频率上面的颤动变细有效。在“变细乐队”的TL和IL的价值每每统一一些堵住的团在惯性的集体时刻统一“变细乐队”的长度和乐队宽度主要取决于质量。

  • 标签: 阻塞质量 结构 板材 传输 平面弯曲波
  • 简介:所谓的blisks,即不可分地bladed磁盘,被描绘由很低粘滞抑制的材料并且使flutter预言更批评。在那个框架,展示片和高eigenfrequency的复杂变丑的空间汽轮机blisk的二维的数字研究(>40kHz)被执行。模拟基于不稳定的雷纳兹平均Navier司烧在频率域线性化的计算并且在重叠在于一不稳定线性(及时)压力地,由泛音不安产生了,在之上一稳定非线性(在空间)流动。空气动力学的抑制系数在节的直径的一个范围上被计算,并且片被预言气动弹性变形地稳定。然而,强烈变化发生并且自从在稳定性的突然、大的偏差出现,是相当批评的。在那上下文,从串联宣传的波浪的性质被评估。如此的一条途径关于罐头也宣传到的不安提供基本知识远地(切上模式)或腐烂(截止模式)。流动的能力被不稳定的不安从串联被转移到的方法强烈影响抑制或放大片运动,这被期望远地。波浪的性质首先从上述的线性化的结果被估计,当时,他们是评估经分解并且最后比较。尽管有分析模型的强壮的假设,一个好协议被发现。结果显示出在cut-on/cut-off条件和稳定性之间的清楚的关联。最不稳定的配置在插头在入口和没有波浪对应于截止模式。没有从串联的出去的波浪,片是容易的不太稳定:从片颤动的体力必然被浪费或由串联发送了。

  • 标签: 颤振稳定性 数值模拟 涡轮叶盘 空间 相位角 亚音速