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97 个结果
  • 简介:Thispaperpresentsreal-timemonitoringdataandanalysisresultsofthenon-stationaryvibrationsofanoperationalwindturbine.Theadvancedtime-frequencyspectrumanalysisrevealsvariednon-stationaryvibrationswithtimevaryingfrequencies,whicharecorrelatedwithcertainsystemnaturalmodescharacterizedbyfiniteelementanalysis.Undertheeffectsofstrongwindload,thewindturbinesystemexhibitscertainresonancesduetobladepassingexcitations.Thesystemalsoexhibitscertaininstabilitiesduetothecouplingofthetowerbendingmodesandbladeflapwisemodewithbladepassingexcitationsunderthevariationofwindspeed.Ananalyticalmodelisusedtoelaboratethenon-stationaryandinstabilityphenomenaobservedinexperimentalresults.ThepropertiesofthenonlinearinstabilitiesareevaluatedbyusingLyapunovexponentestimation.

  • 标签: wind turbine condition MONITORING NON-STATIONARY vibrations
  • 简介:Windshearreflectsthatthewindfieldisnotuniform,whichisoneoftheprimaryfactorswhichmaketheretrievalofthewindfielddifficult.Basedonvolumevelocityprocess(VVP)windfieldretrievaltechnique,theintensityofwindshearisidentifiedinthispaper.Afteranalyzingthetraditionaltechniquesthatrelyonthedifferenceofradialvelocitytoidentifywindshear,afixeddifferenceamongradialvelocitiesthatmaycausefalseidentificationinauniformwindfieldwasfound.Becauseofthenon-uniformityinwindshearareas,thedifferenceofretrievedresultsbetweensurroundinganalysisvolumescanbeusedasameasurementtoshowhowstrongthewindshearis.AccordingtotheanalysisofasevereconvectiveweatherprocessthatoccurredinGuangzhou,itcanbefoundthattheareasofwindshearappearedwiththestrengthsignificantlylargerthaninotherregionsandthemagnitudegenerallylargerthan4.5m/(s·km).Besides,bycomparingthevariationofwindshearstrengthduringtheconvection,itcanbefoundthatnewcellswillbemorelikelytogeneratewhenthestrengthisabove3.0m/(s·km).Therefore,theanalysisofstrongwindshear'smovementanddevelopmentishelpfultoforecastingsevereconvections.

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  • 简介:Thegeophysicalmodelfunction(GMF)describestherelationshipbetweenabackscatteringandaseasurfacewind,andenablesawindvectorretrievalfrombackscatteringmeasurements.ItisclearthattheGMFplaysanimportantroleinanoceanwindvectorretrieval.TheperformanceoftheexistingKu-bandmodelfunctionQSCAT-1isconsideredtobeeffectiveatlowandmoderatewindspeedranges.However,intheconditionsofhigherwindspeeds,theexistingalgorithmsdivergealarmingly.owingtothelackofinsitudatarequiredfordevelopingtheGMFforthehighwindconditions,theQSCAT-1appearstooverestimatethes0,whichresultsinunderestimatingthewindspeeds.Severalmatch-upQuikSCATandspecialsensormicrowave/imager(SSM/I)windspeedmeasurementsofthetyphoonsoccurringinthewestPacificOceanareanalyzed.TheresultsshowthattheSSM/Iwindexhibitsbetteragreementwiththe'besttrack'analysiswindspeedthantheQuikSCATwindretrievedusingQSCAT-1.Onthebasisofthisevaluation,acorrectionoftheQSCAT-1modelfunctionforwindspeedabove16m/sisproposed,whichusesthecollocatedSSM/IandQuikSCATmeasurementsasatrainingset,andaneuralnetworkapproachasamultiplenonlinearregressiontechnologytechnology.InordertovalidatetherevisedGMFforhighwinds,themodifiedGMFwasappliedtotheQuikSCATobservationsofHurricaneIOKE.ThewindestimatedbytheQuikSCATforTyphoonIOKEin2006wasimprovedwiththemaximumwindspeedreaching55m/s.AnerroranalysiswasperformedusingthewindfieldsfromtheHollandmodelasthesurfacetruth.TheresultsshowanimprovedagreementwiththeHollandmodelwindwhencomparedwiththewindestimatedusingtheQSCAT-1.However,largebiasstillexisted,indicatingthattheeffectsofrainmustbeconsideredforfurtherimprovement.

  • 标签: 模型函数 地球物理 台风 应用 检索 转基因食品
  • 简介:ThisstudyinvestigatedtheflowcharacteristicsalteredbyJangBogoAntarcticResearchStationusingcomputationalfluiddynamics(CFD)modeling.ThetopographyandbuildingsaroundJangBogoStationwereconstructedwithcomputeraided-designdataintheCFDmodeldomain.Wesimulated16caseswithdifferentinflowdirections,andcomparedtheflowcharacteristicswithandwithoutJangBogoStationforeachinflowdirection.Thewinddatarecordedbythesite’sautomaticweatherstation(AWS)wereusedforcomparison.WindroseanalysisshowedthatthewindspeedanddirectionaftertheconstructionofJangBogoStationwerequitedifferentfromthosebeforeconstruction.Wealsoinvestigatedhowvirtualwindfenceswouldmodifytheflowpatterns,changingthedistanceofthefencefromthestationaswellastheporosityofthefence.Forwesterlyinflows,whentheAWSwasdownwindofJangBogoStation,thedecreaseinwindspeedwasmaximized(-81%forwest-northwesterly).ThewindspeedreductionwasalsogreaterasthedistanceofthefencewasclosertoJangBogoStation.Withthesamedistance,thefencewithmediumporosity(25%–33%)maximizedthewindspeedreduction.Theseresultssuggestthatthelocationandmaterialofthewindfenceshouldbeselectedcarefully,orAWSdatashouldbeinterpretedcautiously,forparticularprevailingwinddirections.

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  • 简介:Withtheadvancesof数字天气模拟和更新的减少的数据吸收骑车,表面观察数据吸收在数据吸收系统变得越来越重要。一个更好的数据吸收系统应该在表面层包含热力学的进程的限制,这广泛地被接受。在这份报纸,因此,一个新表面风观察操作员在全球、地区性的吸收预言System_3D变化(GRAPES_3D-Var)被利用,与在行星的边界层(PBL)的热力学的过程的限制。为了研究这新表面的能力,在吸收弯屈观察操作员并且预报,一系列实验被使用GRAPES模型操作。主要结果显示表面风观察操作员的这个新方法与GRAPES模型一起在预报上有积极影响。

  • 标签: 数字天气模拟 预报 表面风 数据吸收 热力学的过程的限制 葡萄
  • 简介:Windspeedscalinginsimilaritylawinwind-generatedwavesandthedragcoefficientarestudied.Inanalyzingthedatainthewindwavechannel,itisfoundthattheu.scalinggreatlyreducesthescatterintheU10scaling.Theu.scalinghasmuchlessscatterthanthescalingusingotherwindspeeds.Thefrictionvelocityseemstoplayadistinctiveroleinwavegrowth.Theresultisimportantintheapplicationsofthesimilaritylawandinwavemodeling.Intheoryitgivesaninsightintothemechanismofwindwaveinteraction.Itisfoundthatwavesteepnessisimportantininfluencingthedragcoefficient.Thevariabilityofthecoefficientsinthecurrentlywidelyuseddragformcanbeexplainedbythedifferencesinwavesteepnessintheobservations.Adragcoefficientmodelwithwindspeedandwavesteepnessasparametersisproposed.AnexplanationforKahma'sresultthattheu.scalingdoesnotreducethescatterintheU10scalingisgiven.

  • 标签: 风速 波浪 摩擦系数 海洋
  • 简介:AnellipticalwindfieldmodeloftyphoonsisputforwardbasedonthecharacteristicsofthetyphoonwindfieldsoccurringintheYellowSeaandBohaiSea.Bycontrastingitwiththecirculartyphoonwindfieldmodel,itisfoundthattheellipticalmodelcanadequatelyrepresenttherealwindfieldandtracetheprocessofatyphoonstormsurge.Thenumericallysimulatedresultsofstormsurgesbyusingtheellipticalmodelareingoodagreementwiththeobservationsandmarkedlybetterthanthosebyusingthecircularmodel.

  • 标签: 台风 椭圆风场模型 黄海 渤海 风暴潮 数值模拟
  • 简介:Themainintentionofthepresentstudyistoreducewind,wave,andseismicinducedvibrationsofjackettypeoffshorewindturbines(JOWTs)throughanewlydevelopedvibrationabsorber,calledtunedliquidcolumngasdamper(TLCGD).UsingaSimulink-basedmodel,ananalyticalmodelisdevelopedtosimulateglobalbehaviorofJOWTsunderdifferentdynamicexcitations.ThestudyisfollowedbyaparametricstudytoexploreefficiencyoftheTLCGDintermsofnacelleaccelerationreductionunderwind,wave,andearthquakeloads.StudyresultsindicatethatoptimumfrequencyoftheTLCGDisratherinsensitivetoexcitationtype.Inaddition,whilethegaininvibrationcontrolfromTLCGDswithhighermassratiosisgenerallymorepronounced,heavyTLCGDsaremoresensitivetotheirtunedfrequencysuchthatill-regulatedTLCGDwithhighmassratiocanleadtodestructiveresults.ItisrevealedthatawellregulatedTLCGDhasnoticeablecontributiontothedynamicresponseoftheJOWTunderanyexcitation.

  • 标签: 调谐频率 地震作用 SIMULINK模型 机组性能 液柱 海上
  • 简介:一个城市的边界层模型(UBLM)被合并大楼的效果与改进一部分拖系数和一顶高度分布式的华盖拖长度规模。改进UBLM被使用与不同height-to-width比率在北京区域上在三典型的城市的块上模仿风地。为比较,在一样的块上的风地被明确地解决大楼的一个城市的子域规模模型模仿。从二个不同方法模仿的风地在好同意。然后,为北京的二维的造的词法特征和城市的华盖参数从造高度数据详细说明被导出。最后,experiements被进行用改进UBLM在北京在风地上调查大楼的效果。

  • 标签: 建筑物高度 北京地区 形态特征 风场模拟 城市街区 边界层模式
  • 简介:不同于在行星的边界层的风骚乱光谱上的以前的研究,这调查集中于高高度(15km)在各种各样的天气下面的风精力光谱和骚乱光谱调节。快Fourier变换(快速傅里叶变换)被用来基于风介绍在高高度(15km)计算风精力和骚乱光谱密度雷达(WPR)大小。在在高高度的稳定的天气条件下面的骚乱光谱在2的一个频率范围以内在力量被表示吗??

  • 标签: 风廓线雷达 频谱分析 雷达测量 高海拔地区 快速傅立叶变换 天气条件
  • 简介:Spectralcharacteristicsofwind-generatedwavesinlabortaoryarepresentedonthebasisofasystematicmeasurementinalarge-scalewind-wavechannelandcomparedwiththoseinthefield.Ama-rkedcharacteristicsofthemeasuredspetraistheexistenceofsecondaryspectrum-peak.Thedependenceofspectralpeak-frequency,peak-valueandzeroth-ordermomentonwindspeedandfetcharepresentedandfoundroughlysimilartothoseinthefieldrepresentedbytheJONSWAPspectrum,regardlessofthedifferencesincoefficient.Thespectralslopeβathigh-frequenciesarefoundsomewhatgreaterthanthoseoffieldwind-wavesinbothcasesofdeepandshallowwaters.Exceptforthelow-frequencypart,thespec-tralformsmeasuredindifferentwindconditionsaresimilarandfitfortheJONSWAPspectrumwithγ=6andβ=5.5.Somerelevantproblemsarediscussed.

  • 标签: wind-wave CHANNEL SPECTRAL characteristics JONSWAP SPECTRUM
  • 简介:Bytheuseofthe3/2powerlawpresentedbyTobacombinedwiththesignificantwaveenergybalanceequationforwindwave,windwavegrowthatalimitedfetchisanalyticallyinvestigated.Thenewwindwavegrowthrelations(WWGRs)areanalyticallyderivedwithshelteringcoefficientandwinddragcoefficientasparameters.Thegeometricalaverageofobservationalvaluesofshelteringcoefficientandthearithmeticaverageofobservationalvaluesofwinddragco-efficientareappliedtodeterminethenewWWGRs.ComparisonswithexistingempiricalWWGRsaremade.

  • 标签: WIND WAVE WIND WAVE GROWTH RELATION
  • 简介:在极的坐标并且与在热带气旋的包裹速度在线性变化并且表面压力的分发同意Fujita公式的想象基于原始方程,一套方程被导出,它描述中央压力的不安的影响,风地上的热带气旋的运动的热带气旋,方向和速度的位置。热带气旋的动能的第二顺序近似能被方程在线性近似下面描述,这被证明。台风Wipha(2007)被选择验证上述解释方法,并且结果证明风地的解释方法以前能给很好的结果乍见陆地热带气旋,当不做明显的改进在以后时乍见陆地。在这份报纸的动态解释方法对近改进热带气旋的风地的预报到海岸适用。

  • 标签: 热带气旋 动力学解释 风场 表面压力分布 解释方法 运动速度
  • 简介:由风和水的复杂侵蚀,是也叫的aeolian-fluvialinteractions,在干旱、半干旱的区域是一个重要侵蚀过程和风景。在风和水过程,空间环境转变和时间的环境变化之间的连接的Theeffectiveness是决定风神河的相互作用的geomorphologicsignificance的三个主要驱动力。作为互连的建筑群和内部联合系统,由风和水的复杂侵蚀有空间时间的变化特征。由风和水的复杂侵蚀的过程能被划分成palaeoenvironmental过程和当代的过程。在干燥陆地的早工作经常被归因于倡导an'aeolianist'或一个“河成论者”的二所学校之一观点,因此是直到1930年代关于由风和水的复杂侵蚀的研究被进行了。有二个障碍,由风和水限制复杂侵蚀的研究。第一,怎么在不同时间、空间的规模转变仍然是未解决的;并且第二,研究方法论仍然是不成熟的。以后,侵蚀,在风中的复域土壤侵蚀度和水蚀愿望的机制和控制是关于由风和水的复杂侵蚀的研究的焦点。

  • 标签: 风水复合侵蚀 生态系统 生态环境 半干旱地区
  • 简介:-Driftcurrentinducedbywindandwavesisinvestigatedwithphase-averagedNavier-StokesequationinwhichtheReynoldsstressisclosedbyk-εmodel.Thegoverningequationsaresolvedbythefinitevolumemethodinasystemofnonorthogonalcoordinateswhichisfittedtothephase-averagedwavesurface.Thepredicteddriftcurrentisfairlyreasonableandthedragcoefficientofsea-surfacepredictedwiththenewlydevelopedinterfaceconditionsshowsgoodagreementwithpreviousmeasurementswhenbreakingwavesdonotexist.

  • 标签: DRIFT averaged REYNOLDS NAVIER fairly COORDINATES
  • 简介:在这研究,越过从1956~2004的中国的最大的风速度(WSmax)变化基于观察车站数据被分析,并且为20462065和20802099的WSmax的变化用三个全球气候模型被投射(GFDL_CM2_0,CCCMA_CGCM3,并且MRI_CGCM2)那参予了IPCC第四份评价报告(AR4)。观察到年度、季节的WSmax和强风天的频率显示出明显的衰退趋势。年度WSmax每十年由约1.46ms1减少了,并且强风天的数字从1956~2004每十年到3.0天减少了。年度、季节的WSmax减少的振幅比年度、季节的平均的风速度(WSavg)的那些大。变弱东方亚洲冬季和夏天季风在整个中国上是为WSmax和WSavg的不同减少的原因。在东南的WSmax的减少中国的沿海的区域与在中国和减少的数字的冷波浪的减少的紧张有关(并且减少的紧张)land-falling,台风在西北太平洋发源。全球气候模型GFDL_CM2_0,MRI_CGCM2,和EBGCM(上面的整体提及三个全球气候模型)一致地建议年度、季节的WSmax价值将相对19812000在20462065和20802099期间减少。模型也建议在为整个中国的WSmax的减少在20462065和20802099期间与冷波浪的减少的紧张和冬季季风的减少的紧张有关,并且在在东南的WSmax的减少中国的沿海的区域在一样的时期期间相应于在在夏天的西北太平洋上的热带气旋的减少的数字。

  • 标签: 中国 最大风速 政府间气候变化专门委员会 东南沿海地区 全球气候模型 东亚冬季风
  • 简介:Athree-dimensionalnumericalmodel,EFDC(environmentalfluiddynamicscode)isappliedtothePamlicoRiverEstuary(PRE)ineasternNorthCarolinaoftheUnitedStatestoexaminethewindimpactonpollutantagedistributionsandresidencetime.Aseriesofmodelexperimentsrepresentingbasecase,remote-wind-inducedwaterlevelset-upandlocalwindscasesareconducted.ModelresultsindicatethatthepollutantmeanageandthesystemresidencetimearefunctionsofgravitationalcirculationinthePRE.Thesystemresponsestoremote-wind-inducedwaterlevelset-uparedifferentindifferentportionsofthePRE.Undersuchcondition,dissolvedsubstancesintheupstreamportionofthePREhaveayoungerageandshorterresidencetime(comparedwiththebasecase),bycontrast,theyhaveaolderageandlongerresidencetimeinthedownstreamportionofthePRE.Upriveranddownriverlocalwindsappeartohaveoppositeimpactsonpollutantagedistributions.ThesubstancesareretainedmuchlongerwithinthePREunderupriverwindthanthoseunderdownriverwind.Themodelresultsalsosuggestthatacross-riverwindsmayleadtolongerresidencetimethroughenhancedturbulencemixing,whichslowsdownthegravitationalcirculationinthePRE.

  • 标签: 帕姆利科湾 浅湾 重力循环 盐量
  • 简介:CallaghanandWhite(2009)putforwardtheautomatedwhitecapextraction(AWE)techniquetodeterminethewhitecapcoverage(W).AnimprovedAWEwasusedtoanalyzeimagescollectedintheSouthChinaSeaduring2012and2013andinwesternPacificduring2015todetermineW.Theinfluencesofmeteorologicalandoceanographicfactorsonwhitecapcoveragewereinvestigatedinthisstudy.ItisfoundthatWincreaseswithwindspeed.ScalefactorandexponentofparameterizationforW(U10)varygreatlyindifferentmodels.Overall,thereisalargerscatterofWatlowwindspeedthanathighwindspeed.Wdecreaseswiththeincreasingofwaveage.Comparedwithwindspeed,thescatterofWissmallerwithwaveage,whichmeanstheimpactofwaveageonthewhitecapcoverageismorerobustundervariousenvironmentalconditions.ThereisnosignificantdependenceonSSTandwhitecapcoverageseemstoweaklydecreasewithSST.Wdecreaseswiththeatmosphericstability.RelationshipbetweenWandwindspeedchangewhenswellsaredominant.SwellcansuppresswavebreakinganddecreaseW.Theeffectisindependentofthedeflectionanglebetweenwindwaveandswell.

  • 标签: whitecap COVERAGE AWE WAVE age SST
  • 简介:MultivariateObjectiveAnalysisofWindandHeightFieldsintheTropicsS.K.Sinha,S.G.NarkhedkarandS.Rajamani(IndianinstituteofTropical...

  • 标签: MULTIVARIATE OPTIMUM INTERPOLATION scheme DIVERGENT part