学科分类
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63 个结果
  • 简介:Semi-periodicstructuresnamelyinclinedwavystructures(IWS)areexperimentallyobservedincompressiblemixinglayersattwoconvectiveMachnumbers(Mc=0.11and0.47).FlowstructuresarevisualizedbythelaserinducedplanarlaserMiescattering(PLMS)technique.TwomethodsaredevelopedtoinvestigatethespatialdistributionandgeometryofIWS:(1)thedominantmodeextraction(DME)method,toextractthedominantmodesofIWSfromthestreamwisegray-levelfluctuation,and(2)thephasetracking(PT)method,toidentifytheshapeofIWS.TheresultssuggestthatpressureperturbationsaccountfortheformationofIWSintheinitialmixingregionandthejointefectofdilatationandcoherentvorticesenhancesIWSinthewelldevelopedregion.Thelargetransverse(cross-flow)scaleoftheIWSandtheirrelationtocoherentvortices(CV)indicatethatthedisturbanceoriginatedfromCVinthemixingcenterpropagatesfarintothefreestreams.TheDMEandthePTmethodareshowntobetheefectivetoolstostudythegeometricalfeaturesofwavystructuresincompressibleshearflows.

  • 标签: 可压缩混合层 波浪结构 几何形状 MIE散射 周期结构 波纹结构
  • 简介:Compressedthinlayersofceramicfiberinsulationareusedashightemperatureinsulatinglayersaswellasmechanicalsupportforcatalystcoatedceramicmonolithsinautomotiveemissioncontroldevices.Minimizationofenergylosses,choiceofmaterialandthicknessofcompressedinsulatinglayerarebasedonknowledgeoftheirthermalphysicalproperties.Currently,consistentmeasurementsofmaterialsinacompressedstate,astheywouldbeinemissioncontrolapplications,areabsentduetotheabsenceofsuitablemethodsforsuchtests.Atestmethodwasdevelopedformeasurementofthethermalconductivityofcompressedthinfiberlayers.Thispapersummarizestheresultsofthermalconductivityanddiffusivitymeasurementsof27compressedfiberalumina-silica-vermiculitematerialsintherangeof200-950℃.Thermalphysicalpropertiesasafunctionoftemperature,density/mechanicalpressure,thicknessandcompositionofinsulatinglayersarepresented.Thewholesetofexperimentaldataisgeneralizedon3Dsurfaceplotsanddescribedbypolynomialfunctions.Thepossibleheattransfermechanismsgoverningapparentthermalconductivityofpressedinsulationlayersarediscussed.

  • 标签: 压缩状态 陶瓷纤维 绝缘层 排放控制装置 表观导热系数 热物理性能
  • 简介:Climatologyoftheisothermallayerdepth(ILD)andthemixedlayerdepth(MLD)hasbeenproducedfromin-situtemperature-salinityobservationsintheEastChinaSea(ECS)since1925.ThemethodsappliedontheglobalareusedtocomputetheILDandtheMLDintheECSwithatemperaturecriterionΔT=0.8℃fortheILD,andadensitycriterionwithathresholdΔσθcorrespondingtofixedΔT=0.8℃fortheMLD,respectively.WiththederivedclimatologyILDandMLD,themonthlyvariationsofthebarrierlayer(BL)andthecompensationlayer(CL)intheECSareanalyzed.TheBLmainlyexistsintheshallowwaterregionoftheECSduringApril-Junewiththicknesslargerthan15m.FromDecembertonextMarch,theareaalongtheshelfbreakfromnortheastofTaiwanIslandtothenortheastECSischaracterizedbytheCL.Twokindsofmaintemperature-salinitystructuresoftheCLinthisareaaregiven.

  • 标签: 等温层深度 混合层深度 阻挡层 东海
  • 简介:Atheoreticalinvestigationiscarriedouttostudytheexistence,formationandbasicpropertiesofionacoustic(IA)doublelayers(DLs)inamagnetizedbi-ionplasmaconsistingofwarm/coldionsandBoltzmanndistributedelectrons.Basedonthereductiveperturbationtechnique,anextendedKortewegde-Vries(KdV)equationisderived.Thepropagationoftwopossiblemodes(fastandslow),andtheirevolutionareinvestigated.Theeffectsofobhqueness,magnitudeofthemagneticfield,ionconcentration,polarityofions,andiontemperatureontheIADLprofileareanalyzed,andthentherangesofparametersforwhichtheIADLsexistareinvestigatedindetails.

  • 标签: ION ACOUSTIC WAVES bi-ion PLASMA DOUBLE-LAYERS
  • 简介:Throughderivingexpressionsrelatingthedip-angle((?)_m)ofthelowerboundaryofalayertotheacousticvelocity(v_m)ofthelayerandotherpre-determinableparameters,v_mand(?)_mcanbetakenassimultaneouslyiterativevariableswhilesolvingShah‘sequations.Consequentlythepreviousmethodofcomputingv_mand(?)_mpresentedbyZHANGS.isimproved,andtheaccuracyofsolutionsincreasedgreatly.

  • 标签: ITERATIVE arbitrarily successive CALCULATING instead operations
  • 简介:一个沉积地质的模型被建立以便学习隧道沙身体的地震思考特征。合成地震射击集合用声学的波浪方程被模仿然后prestack时间被移植。在想象的数据上,思考特征和即时属性被分析,抑制木头的阻抗倒置被测试。因为波浪领域干扰,试验性的结果证明地震事件毫无疑问不对应于隧道沙身体并且出现的地震模式不代表实际的。波浪干扰形成的地震事件可以在沙身体解释导致错误和陷井。在即时地震属性和沉积的沙之间的相应关系很好没被建立。抑制木头的阻抗倒置改进隧道沙的决定。然而,如果转换分辨率被强迫太高,与起始的模型有关的人工制品可以发生。

  • 标签: 地震反射性状 河床砂 波场模拟 阻抗倒置
  • 简介:Thevelocityprofile,turbulenceintensityprofile,streakystructureandburstingfrequencyinturbulentboundarylayersoveraflatplatewithcompliantcoatingswereinvestigatedbyLaserDopplerAnemometryandcondi-tionalsamplingtechniques.Thisexperimentledtotheconclusionsthatinboundarylayerflowsonacompliantwall,ascomparedwiththatonarigidwall,theloglawregionwasextendedfurtherawayfromthewall,andthatthemaximumvalueofeachturbulenceintensityprofileinthenearwallregionwasreducedandtheburstingfrequencyobviouslydecreasedwiththecompliantcoatings.Onepointworthyofnoticewasthattheaboveresultswereverymuchlikethoseofpolymerdragreductionexperiments.

  • 标签: compliant COATING COHERENT STRUCTURE
  • 简介:这份报纸被建议理解卟啉层的相互作用,两价的分子由使用abinitio和密度在他们的内部区域交往功能的理论(DFT)方法。我们不使用了,公司,和O2与卟啉层交往的两价的分子。有有N4核心的tetra-pyrrlic戒指的最普通的集中Fe的metalloporphyrin结构为学习被选择。卟啉卟啉的优化(P我-PII)和卟啉两价的分子--卟啉(P我-AB-PII)(AB=没有,公司,和O2)建筑群用HF被执行方法。为了理解planarity并且拨出叠,卟啉并且也缩放推断在卟啉层之间的两价的分子的分离P我-AB-PII建筑群(在哪儿AB=没有,公司,并且O2)用结构的性质和分子的静电的潜力(MEP)被分析。MEP用与6-31+G*基础一起的DFT的功能的B3PW91为P我-PII和P我-AB-P从HF获得的II建筑群方法。

  • 标签: 相互作用 铁卟啉 层结构 化学研究 双原子分子 密度泛函理论
  • 简介:Thestabilitycharacteristicsoflaminarboundarylayersovercompliantwallswasstudiedbythelineartheory.Unlikethepreviousauthors,thecoupledmotionofthefluidandsolidwasrequiredtosat-isfythecontinuityconditionsofboththevelocityandstressattheinterface.Resultsofcalculationsshowthatasthespeedratioordensityratioexceedsacertainthresholdvalue,thetwotypesofunstablewaveswillnolongerbedistinguishable,andthetangentialcomponentofthedisturbancestressisnolongernegligi-ble.Sotheneglectofit,asthepreviousauthorsdid,isunjustified.

  • 标签: STABILITY BOUNDARY LAYER compliant WALL
  • 简介:ThispaperpresentsanewfamilyofsolutionstothesingularlyperturbedAllen-Cahnequationα~2Δu+u(1-u~2)=0inasmoothboundeddomainΩR~3,withNeumannboundaryconditionandα>0asmallparameter.Thesesolutionshavethepropertythatasα→0,theirlevelsetscollapseontoaboundedportionofacompleteembeddedminimalsurfacewithfinitetotalcurvatureintersecting?Ωorthogonallyandthatisnon-degeneraterespectto?Ω.Theauthorsprovideexplicitexamplesofsurfacestowhichtheresultapplies.

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  • 简介:2017年4月22日,“层像Layers——大卫·歌诗坦个展”将于北京今日美术馆l、2层盛大开幕。本次展览展出大卫·歌诗坦十年来创作的近百件剪切式雕塑,展览时间将持续到2017年5月16日。此次雕塑展览全面地展现了大卫·歌诗坦独特的个人艺术风格,将“剪切式雕塑”配以斑谰的色彩,作品的表达主题贴近人们的日常生活,在增强感染力的同时更能让观众产生思想共鸣。

  • 标签: 歌诗 大卫 雕塑展览 展览时间 艺术风格 日常生活
  • 简介:Atechniqueispresentedforcreatingsurface-adheringdustlayersunderdefinedconditions,andcharacterizingandstressingthelayerscreated.Theproceduredescribedisshowntobesuitableforthequantitativeevaluationoftheeffectsofdifferentparameterssuchasparticlesize,porosityandsurfaceroughnessetc.onthestabilityofparticlelayers.

  • 标签: 粒子层流 结构强度 层流分离 应力特征
  • 简介:Thispapergivesanintroductionintothedissipationintegralmethod.Thegeneralintegralequationsforthethree-dimensionalcasearederved.Itisfoundthatforapracticalcalculationalgorithmtheintegralmonentumequationandtheintegralenergyequationaremsotuseful.UsingTwodifferentsetsofmeanvelocityprofilesthehyperbolicalcharacterofadissipationintegralmethodisshown.Testcasesfortwo-andthree-dimensionalboundarylayersareanalysedanddiscussed.Thepaperconcludeswithadiscussionoftheadvantagesandlimitsofdissipationintegralmethods.

  • 标签: 湍流边界层 积分方法 流体力学
  • 简介:TheeffectsofgrowthtimeonthestructureandmorphologyofcubicGaNnucleationlayersonGaAs(001)substratesbymetalorganicchemicalvapordeposition(MOCVD)havebeeninvestigatedusingasynchrotronX-raydiffraction(XRD).TheXRDresultsshowthattheGaN111reflectionsat54.75°inχareameasurablecomponent,howeverthe002reflectionsparalleltoGaAs(001)surfacearenotdetected.TheXRDΦscansandpolefiguresgiveaconvincingproofthattheGaNnucleationlatyersshowexactlythecubicsymmetricalstructure.Thecoherencelengthsalongtheclose-packed<111>directionestuimatedfromthe111peakarenanometerorderofmagnitude,Theoptimalphotoluminescence(PL)spectrumwasobtainedfromthecubicGaNepilayerdepositedonthenucleationlayerfor60sec.

  • 标签: GaN 成核层 GAAS衬底
  • 简介:Inthispaper,usingLin'sintegralidentitytechnique,weprovetheoptimaluniformconvergenceθ(N_x~(-2)In~2N_x+N_y~(-2)In~2N_y)intheL~2-normforsingularlyper-turbedproblemswithparaboliclayers.Theerrorestimateisachievedbybilinearfi-niteelementsonaShishkintypemesh.HereN_xandN_yarethenumberofelementsinthex-andy-directions,respectively.Numericalresultsareprovidedsupportingourtheoreticalanalysis.

  • 标签: 抛物线方程 椭圆问题 有限元分析 收敛性
  • 简介:作者调查Prandtl边界层理论能严厉地为被验证的边界层的一些例子。所有为与各种各样的Dirichlet边界条件(指定速度)装备的牛顿的液体与不可压缩的海军司烧方程他们被联系。这些例子包括一个家庭(非线性的3D)飞机平行流动,一个家庭(非线性)有在边界的一致注射和吸的平行管子流动,以及流动。我们也在建立Prandtl类型理论的有效性识别关键成分,即,一光谱海军司烧系统的近似答案上的限制由联合Prandtl类型系统的inviscid答案和解决方案构造了。这是除与Prandtl类型系统的well-posedness有关的著名问题以外的一个另外的困难。看起来主要阻塞到确认光谱限制状况是边界层的可能的分离。这些例子的一个普通主题也经由在边界压制速度正常到边界或由注射和吸以便是边界层的分离的抑制光谱限制能被验证。一条元定理然后被介绍它盖住这里考虑的所有盒子。

  • 标签: STOKES方程 边界层理论 不可压缩 DIRICHLET边界条件 kes系统 边界层分离
  • 简介:Thespatialevolutionof2-Ddisturbancesinsupersonicsharpconeboundarylayerswasinvestigatedbydirectnumericalsimulation(DNS)inhighordercompactdifferencescheme.Theresultssuggestedthat,althoughthenormalvelocityinthesharpconeboundarylayerwasnotsmall,theevolutionofamplitudeandphaseforsmallamplitudedisturbanceswouldbewellinaccordancewiththeresultsobtainedbythelinearstabilitytheory(LST)whichsupposestheflowwasparallel.Theevolutionofsomefiniteamplitudedisturbanceswasalsoinvestigated,andthecharacteristicoftheevolutionwasshown.Shockletswerealsofoundwhentheamplitudeofdisturbancesincreasedoversomevalue.

  • 标签: 直接数字模拟 混乱问题 振幅 相位 流体力学