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

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简介：请家长帮忙制作背景，使Alfi能在山上自由上下。1在鞋盒里画出高山的场景图。2用铅笔穿透盒子顶部，把线轴套在铅笔上。

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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：Theauthorshadinventedtheuniquewindpowerunitcomposedofthelarge-sizedfrontwindrotor,thesmall-sizedrearwindrotorandthepeculiargeneratorwiththeinnerandtheouterrotationalarmatureswithouttheconventionalstator.Thisunitiscalled'IntelligentWindPowerUnit'bytheauthors.Thefrontandtherearwindrotorsdrivetheinnerandtheouterarmatures,respectively,whiletherotationaltorqueiscounter-balancedbetweenbotharmatures/windrotors.Thispaperdiscussesexperimentallytheacousticnoisefromthefrontandtherearwindrotors.Theacousticnoise,inthecounter-rotatingoperation,isinducedmainlyfromtheflowinteractionbetweenbothrotors,andhasthedominantpowerspectrumdensityatthefrequencyofthebladepassinginteraction.Thenoiseiscausedmainlyfromtheturbulentfluctuationduetotheflowseparationontheblade,whentherearwindrotorstopsorrotatesinthesamedirectionasthefrontwindrotor.

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.

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：TosolvetheproblemintheabsenceofpermeabilityalgorithminChina’sforestryindustrystandard"TechnicalSpecificationforOasisShelterBeltConstruction(LY/T1682—2006)",bydefiningandcalculatingtheforeststructuralparameters-porosityβ,stumpagesurfaceporosityS",stumpagevolumeporosityV’,abovegroundsurfaceareadensityC,abovegroundbulkdensityW,therelationsamongthesestructuralparametersandtheirrelationswithwindpermeabilitycoefficientα,shelterbeltwidthDandmeandiameterofbranchdwerecalculated,whichisexpressedas:W=V’/D=dC/4=dS’/4D=-πdlnβ/4D=-0.1πZdlnα/D.Itisproofedthatthemainstructuralparametershavehomogeneityanddifferentstructuralparametersareofinheritanceandconsistencyonthenature,thereisnoexclusivityinthestrictsense,andisconvertibleundercertainconditions,whichisconvenientforevaluatingthewind-resistanceeffectofshelterbelt.AsetofcomputationalformulasforwindeffectevaluationoffarmlandshelterbeltindryandsandyareainnorthernChinaisderived.

简介：Thispaperpresentsanapplicationofgain-scheduling(GS)controltechniquestoafloatingoffshorewindturbineonabargeplatformforaboveratedwindspeedcases.Specialemphasisisplacedonthedynamicsvariationofthewindturbinesystemcausedbyplantnonlinearitywithrespecttowindspeed.Theturbinesystemwiththedynamicsvariationisrepresentedbyalinearparameter-varying(LPV)model,whichisderivedbyinterpolatinglinearizedmodelsatvariousoperatingwindspeeds.Toachievecontrolobjectivesofregulatingpowercaptureandminimizingplatformmotions,bothlinearquadraticregulator(LQR)GSandLPVGScontrollerdesigntechniquesareexplored.ThedesignedcontrollersareevaluatedinsimulationswiththeNREL5MWwindturbinemodel,andcomparedwiththebaselineproportional-integral(PI)GScontrollerandnon-GScontrollers.ThesimulationresultsdemonstratetheperformancesuperiorityofLQRGSandLPVGScontrollers,aswellastheperformancetrade-offbetweenpowerregulationandplatformmovementreduction.

简介：(1)Chinaisvastinterritoryandrichinnaturalresources.Ithasdiversifiedpopula-tionanditsenergyresourcesareunevenlydistributed.Inthepastmorethantenyears,therehasbeenagreatgapbetweende-mandandsupplyinelectricity.Inordertosolvethisproblem,theChineseGovern-mentpaysgreatattentiontodevelopwindenergyandnewenergypoliciesofsuitabletothelocalconditions,multi-functionsfor

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。

简介：Windpowerpredictioniscrucialtotheoperationofthepowersystemaccommodatingalargeamountofwindpower.Fromtheperspectiveofpowerdispatch,thispaperdiscussesthecurrentsituationsofthetechnology,systembuilding,predictionerrors,theindexforevaluatingwindpowerpredictionsystemandthemainbodiesresponsiblefortheprediction.Itdelvesintotheexistingproblemssuchasincompletebasicdata,poorpredictionaccuracy,shortpredictiontimescale,aswellaslackingofpredictioninmostwindfarms.Suggestionsonimprovementareproposedincludingenhancingtheconstructionofwindpowerpredictionsystemonboththegridsideandthewindfarmside,speedingupthedevelopmentofultra-shorttermwindpowerpredictionsystem,deepeningtheresearchonwindpowerpredictiontechnology,strengtheningtheconstructionoftechnicalstandardsystemandcarryingoutcross-sectorcooperation.

简介：风，是指由于气压分布不均匀而产生的，与地面大致平行的空气流动。提到风，我们首先便会想到wind。但除此之外，还有breeze、gale、typhoon等等。

简介：Windspeedscalinginsimilaritylawinwind-generatedwavesandthedragcoefficientarestudied.Inanalyzingthedatainthewindwavechannel,itisfoundthattheu.scalinggreatlyreducesthescatterintheU10scaling.Theu.scalinghasmuchlessscatterthanthescalingusingotherwindspeeds.Thefrictionvelocityseemstoplayadistinctiveroleinwavegrowth.Theresultisimportantintheapplicationsofthesimilaritylawandinwavemodeling.Intheoryitgivesaninsightintothemechanismofwindwaveinteraction.Itisfoundthatwavesteepnessisimportantininfluencingthedragcoefficient.Thevariabilityofthecoefficientsinthecurrentlywidelyuseddragformcanbeexplainedbythedifferencesinwavesteepnessintheobservations.Adragcoefficientmodelwithwindspeedandwavesteepnessasparametersisproposed.AnexplanationforKahma'sresultthattheu.scalingdoesnotreducethescatterintheU10scalingisgiven.