简介:Theturbulentfluxesforsensibleandlatentheatandmomentumarecomputedandanalysesarecarriedoutaboutthefactorsintermsofthefluxes,withtheprofilemethods,basedonthedatafromtheTibetan(Xi-zang)PlateauMeteorologicalExperimentin1986(TIPMEX-86).Itisshownthatthefluxesofvariouskindshaveevidentdiurnalvariation,andeachdecademeandiurnalvariationisquitedifferentfromothers.Thesensibleheatfluxisabout2/3lessinJulythaninJune.Theresultsindicatethattheaverageddragcoefficient,C_d,andtheaveragedbulktransfercoefficientofsensibleheat,C_h,are0.0052and0.0075respectively,fortheperiod13to28inJuneforNagqu.ButforLhasa,themeanC_dis0.0056,andthemeanC_his0.0085,fortheperiodofJune11toJuly20.ItisfoundthatC_dandC_harenotonlythefunctionofwindvelocity,butalsoinfluencedbystabilityconditionsandwindandtemperaturegradients.
简介:现在的学习考虑发展混合被开始二条免费溪流合并形成的层由一个裂解槽盘子分开了。在粒子分散上调查旋涡的结构的影响,当时,数字模拟被进行速度比率,定义为R=U_∞-U_(-∞)/U_∞+U_(-∞),是0。5。大旋涡的模拟(LES)被采用理解大规模旋涡的结构的效果在质点分散上由theKelvin-Helmholtz不稳定性发源。有粒子的苍蝇灰缩放10,50,100,150,并且200um分别地在二维的混合层的起源被装载。Itis证实粒子分散强烈取决于大规模旋涡的结构的运动。粒子分散被在经历配对相互作用的混合的层跟随粒子轨道数字地设想。
简介:Verticallyexploringthecharacteristicsofthetyphoonboundarylayer(TBL)playsanimportantroleinrecognizingtyphoonstructure.TheboundarylayerradialdirectionandtangentialwindcharacteristicsofTyphoonUsagibasedontheobservationaldataofthreeboundarylayerwindprofilerstationsalongtherouteofTyphoonUsagi(No.1319)andbycombiningwithsoundingdata.Theresultsshowthat:(1)maximumtangentialwindappearsinthevicinityoftheeyeareaofUsagi,anditbasicallymaintainsaheightofaround1800mwhenUsagikeepsastrongtyphoonlevel,withtherapidlydecreasingstrengthofUsagiafteritlands,thespeedofthemaximumtangentialwindanditsverticalrangebothdecrease;(2)theheightofthemaximumtangentialwindisclosetothatoftheinflowlayertopofthetyphoon,andisgreaterthanthatoftheboundarylayerestimatedonthebasisofRichardsonnumberorpotentialtemperaturegradient,whiletheheightofmixedlayerjudgedonthebasisofthesignal-to-noiseratio(SNR)oritsgradientisusuallylow;(3)thetheboundarylayerheightcanreachhigherthan2100mbeforeUsagilands.Whenthetyphoonleveloraboveisachieved,theboundarylayerheightobservedbyvariousstationsdoesnotchangemuch,basicallystayingatbetween1200and1600m.WiththedecreasingstrengthofUsagiafteritslandfall,theboundarylayerheightrapidlydrops.
简介:Temporalmodedirectnumericalsimulationwasdonefortheprocessoflaminar-turbulenttransitioninanincompressibleboundarylayeronaflatplate.Theanalysisoftheresultsshowedthatduringthebreakdownprocessoflaminar-turbulenttransition,themodificationofthemeanflowprofilebythedisturbancesledtoaremarkablechangeinitsstabilitycharacteristics,manifestedinthesignificantenlargementofthelinearunstablezoneandthemaximumamplificationrate,andledtothatmanymoredisturbanceswereexcitedandenhancedrapidly,correspondinglytheturbulentenergyalsoincreasedrapidly,andthemeanflowprofilesevolvedswiftlyfromlaminartoturbulent.Itwasalsofoundthatiftheobliquewavesintheinitialdisturbancesdidnotformsymmetricalpairs,thesubsequentspan-wisemeanvelocitieswould,ingeneral,benonzeroduetononlinearinteraction,whichwouldhaveagreateffectonthestabilitycharacteristicsandalsoimpliedthattheturbulenceobtainedbydirectnumericalsimulationmightnotbefullyarandomprocess.
简介:Thispaperreportsthatanexperimentalstudyisconductedtoexaminethedynamicsoftheoutflowintwo-layerexchangeflowsinachannelconnectingbetweentwowaterbodieswithasmalldensitydifference.TheexperimentsrevealthegenerationofKelvin-Helmholtz(KH)instabilitieswithinthehydraulicallysub-criticalflowregionofthechannel.Duringmaximalexchange,thoseKHinstabilitiesdevelopsintolarge-amplitudeKHwavesastheyescapethechannelexitintothereservoir.Thepropagationspeed...
简介:Theresearchisabouttheeffectofalayerofvaryingdensityofsea-bottomsedimentsonspatialcorrelationofsea-bottombackscattering.Therelationshipbetweenscatteringcrosssectionandspatialcorrelationisthatbackscatteringcrosssectiondecreasesquicklyandthespatialcorrelationbecomesstrongerastheincidentangleincreases.Therefore,thedensitydepthprofileisintroducedintosea-bottomhigh-frequencybackscatteringechomodel,whichisusedtosimulatesea-bottombackscatteringandcalculatethefunctionofspatialcorrelation.Theinfluenceofthedensitygradientonspatialcorrelationofsea-bottombackscatteringisinvestigatedbyanalyzingtherelationsbetweenverticalgradientofdensityandthescatteringcrosssection.Ascanbeseenfromthesimulationresults,theimpactofthedensitygradientonthespatialcorrelationisfoundmoresignificant.Whilethedensitygradientincreases,thescatteringcross-sectionandtheradiusofthespatialcorrelationbroaden,thespatialcorrelationbecomesstronger.Atthesametime,thescatteringcross-sectiondecreasesmorequicklyastheincidentangleincreases.
简介:Background:Understoryplantsrepresentsthelargestcomponentofbiodiversityinmostforestecosystemsandplaysakeyroleinforestfunctioning.Despitetheirimportance,theinfluenceofoverstory-layercompositiononunderstoryplantdiversityisrelativelypoorlyunderstoodwithindeciduous-evergreenbroadleavedmixedforests.Theaimofthisworkwastoevaluatehowtreeoverstory-layercompositioninfluencesonunderstory-layerdiversityinthreeforesttypes(monospecificdeciduousNothofaguspumilio(Np),monospecificevergreenNothofagusbetuloides(Nb),andmixedN.pumilio-N.betuloides(M)forests),comparingalsobetweentwogeographicallocations(coastandmountain)toestimatedifferencesatlandscapelevel.Results:Werecorded46plantspecies:4ferns,12monocots,and30dicots.Canopy-layercompositioninfluencestheherb-layerstructureanddiversityintwodifferentways:whilemixedforestshavegreatersimilaritytoevergreenforestsintheunderstorystructuralfeatures,deciduousandmixedweresimilarintermsofthespecificcompositionofplantassemblage.Deciduouspurestandswerethemostdiverse,meanwhileevergreenstandswereleastdiverse.Lackofexclusivespeciesofmixedforestcouldrepresentatransitionwhereevergreenanddeciduouscommunitiesmeetandintegrate.Moreover,landscapehasamajorinfluenceonthestructure,diversityandrichnessofunderstoryvegetationofpureandmixedforestslikelyassociatedtothemagnitudeandfrequencyofnaturaldisturbances,wheremountainforestnotonlyhadhighestherb-layerdiversitybutalsomoreexclusivespecies.Conclusions:OurstudysuggeststhatmixedNothofagusforestsupportscoexistenceofbothpuredeciduousandpureevergreenunderstoryplantspeciesanddifferentassemblagesincoastalandmountainsites.Maintainingthemixtureofcanopypatchtypeswithinmixedstandswillbeimportantforconservingthenaturalpatternsofunderstoryplantcompositioninsouthernbeechmixedforests.
简介:Basedontheresearchoftheconvectiveboundarylayer(CBL)temperaturefieldinaconvectivetank,thispaperstudiesthecharacteristicsoftheCBLvelocityfieldintheconvectivetank.Aluminiumpowder(400orders)isusedasatracerparticleintheapplicationoftheparticleimagevelocimetry(PIV)technique.Theexperimentdemonstrates:thevelocitydistributioninthemixedlayerclearlypossessesthecharacteristicsofCBLthermals;thevelocitydistributioninthetopzoneofthemixedlayershowsentrainmentlayercharacteristics;theverticaldistributionofturbulentcharacteristicvariablesisreasonable,whichissimilartofieldobservationsandothertankresults;theerroranalysisdemonstratesthevalidityofaluminiumpowder,whichimpliesthereliabilityoftheresults.
简介:轧了nanorods被磁控管劈啪作响和加氨系统综合,并且Tb中间的层的厚度被改变学习效果在上轧了nanorods。结果被扫描电子测试显微镜学(SEM),X光检查衍射(XRD),传播电子显微镜学(TEM),高分辨率的传播电子显微镜学(HRTEM),和光致发光(PL)系列。结果证明Tb层的厚度在形式,质量,和光性质上有明显的效果轧了nanorods。在房间温度的PL系列在368点显示出一座很强壮的排放山峰?nm和弱排出物在387点达到顶点?当Tb层是20时,为生产样品的山峰的nm,和紧张到达最大值?nm。最后,20的最佳的厚度?为综合的Tb中间的层的nm轧了nanostructures被完成。
简介:TheDebyeequationwithslit-smearedsmallanglex-rayscattering(SAXS)dataisextendedformanidealtwo-phasesystemtoapseudotwo-phasesystemwiththepresenceoftheinterfacelayer,andasimpleaccuratesolutionisproposedtodeterminetheaveragethicknessoftheinterfacelayerinporousmaterials.ThismethodistestedbyexperimentalSAXSdata,whichweremeasuredat25℃,oforgano-modifiedmesoporoussilicapreparedbycondensationoftetraethoxysiland(TEOS)andmethyltriethoxysilane(MTES)usingnon-ionicneutralsurfactantastemplateunderneutralcondition.
简介:在精力平衡实验期间,patch-to-patch灌溉在一块纵贯的面向的棉花地里在土壤潮湿产生了坡度。从相对干燥的在上游的补丁由于强壮的水平移流开发相对弄湿下游的补丁的内部边界层(IBL)与占优势的在北方的风联系了。这产生了多重尺寸的大旋涡,它在IBL在骚乱的结构上有重要影响。在IBL以内在二高度测量的风速度,温度,湿度,和精力流动的力量系列和cospectra被介绍并且过去常在表面层骚乱上调查IBL的影响。系列和cospectra被外部骚乱极大地在低频率提高。这些骚乱的山峰频率没随着高度变化。系列和cospectra典型地收敛了并且与在高频率的堪萨斯光谱平行(在惯性的子域)。当表面层是稳定的时,在水平风速度的系列的清楚的差距在中间的频率存在。结果显示在在上游的对流边界层发源的大旋涡在表面层骚乱的系列和cospectra上有可观的影响。这些大旋涡的影响更大(1)当IBL比IBL什么时候没存在在近的表面层是开发得好的时,(2)在比在底层高级,并且(3)当大气的表面层(ASL)比ASL什么时候是稳定的不稳定时。这些大旋涡的长度规模与在实验地点的表面异质的主导的规模一致。
简介:Atunablephotoniccrystal(PC)filterisproposedwiththetwistednematic(TN)liquidcrystal(LC)asadefectlayer.Thepolarizationsensitiveperformanceandtheeigenmodesareanalyzed.Theresultsshowthattherearetwokindsoftransmissionmodes,namelyoande,whenthevoltageislow.Thedifferentmodescanbeselectedbyrotatingthefilteraxially.Theemodeshiftstowardtheshorterwavelengthsideastheappliedvoltageincreases.Thenthepeaksoftwomodesmergeintoeachotherandthepolarizationsensitiveperformancedisappears.Thephotonicbandgapisinsensitivetothevoltage.Thetunablerangeofthefilteris53nm.
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简介:SeasonalvariationandtopographyofthemixedlayerintheSeaofJapanarestudiedbycomparisonofresultsfromlong-termobservationdataanalysisandfromnumericalsimulationwiththeMHIoceanicmodel(Shapiro.1998.MarineHydrophysicalJournal,6:26~40).ThedataareretrievedfromOceanographicAtlasoftheBeringSea,OkhotskSea,andJapan/EastSea(Rostov,Rostov,Dmitrieva,etal.2003.PacificOceanography,1(1):70~72).Thesimulatedandlong-termpatternsarecompared.Animpactofsurfacebuoyancyflux,wind,andconvergence/divergenceofsurfacecurrentsuponthemixedlayerintheSeaofJapanisanalyzed.
简介:Thesingle-layerlatticedcylindricalshellisoneofthemostwidelyadoptedspace-framedstructures.Inthispaper,freevibrationpropertiesanddynamicresponsetohorizontalandverticalseismicwavesofsingle-layerlatticedcylindricalshellsareanalyzedbythefiniteclementmethodusingANSYSsoftware.Inthenumericalstudy,wherehundredsofcaseswereanalyzed,theparametersconsideredincludedrise-spanratio,length-spanratio,surfaceloadandmembersectionsize.Moreover,tobetterdefinetheactualbehaviorofsingle-layerlatticedshells,thestudyisfocusedonthedynamicstressresponsetobothaxialforcesandbendingmoments.Basedonthenumericalresults,theeffectsoftheparametersconsideredonthestressesarediscussedandamodifiedseismicforcecoefficientmethodissuggested.Inaddition,someadvicebasedontheserescarchresultsispresentedtohelpinthefuturedesignofsuchstructures.