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500 个结果
  • 简介:Theturbulencestructuresnearashearedair-waterinterfacewereexperimentallyinvestigatedwiththehydrogenbubblevisualizationtechnique.Sur-faceshearwasimposedbyanairflowoverthewaterflowwhichwaskeptfreefromsurfacewaves.Resultsshowthatthewindshearhasthemaininfluenceoncoher-entstructuresunderair-waterinterfaces.Low-andhigh-speedstreaksformintheregionclosetotheinterfaceasaresultoftheimposedshearstress.Whenacertainairflowvelocityisreached,'turbulentspots'appearrandomlyatlow-speedstreakswithsomecharacteristicsofhairpinvortices.Atevenhighershearrates,theflowneartheinterfaceisdominatedprimarilybyintermittentburstingevents.Thecoher-entstructuresobservednearshearedair-waterinterfacesshowqualitativesimilaritieswiththoseoccurringinnear-wallturbulence.However,afewdistinctivephenomenawerealsoobserved,includingthefluctuatingthicknessoftheinstantaneousboundarylayerandverticalvorticesinburstingprocesses,whichappeartobeassociatedwiththecharacteristicsofair-waterinterfaces.

  • 标签: AIR-WATER interface surface SHEAR COHERENT structures
  • 简介:到空气的从水的健全传播由于在空气和水阻抗之间的一个大对比是很弱的,这是传统的信仰。最近,提高的健全传播和空气水接口的异常透明性被介绍了。声音由在深度局部性的沉没浅深度单极点来源产生了的空气水接口状态的异常透明性不到1/10声音波长,能与全向的模式被播送进空气。产生声音与古典光线理论预言相比有高35倍的力量。在这份报纸,通过空气水接口鸣传播为一局部性在水下浅深度来源被检查。完成这,在空气水的二阶段的媒介的二阶段的联合Helmholtz波浪方程被商业有限元素解决基于的COMSOLMultiphysics软件。不同健全来源在的压力振幅的比率二不同在水下并且空气坐标对来源深度(D)的非维的比率被计算并且分析到健全波长()。获得的结果与试验性的数据相比,好同意被显示。

  • 标签: 空气-水界面 声音传输 数值研究 低频声 平滑 异常声音
  • 简介:Intheair-waterquantumkeydistribution(QKD),theirregularseasurfacehassomeinfluenceonthephotonpolariza-tionstate.Thewindisconsideredasthemainfactorcausingtheirregularity,sothemodelofirregularseasurfacebasedonthewindspeedisadopted.Therelationshipsofthequantumbiterrorratewiththewindspeedandtheinitialincidentanglearesimulated.Therefore,themaximumsecuretransmissiondepthofQKDisconfirmed,andthelimita-tionofthewindspeedandtheinitialincidentangleisdetermined.Thesimulationresultsshowthatwhenthewindspeedandtheinitialincidentangleincrease,theperformanceofQKDwillfalldown.Undertheintercept-resendattackcondition,themaximumsafetransmissiondepthofQKDisupto105m.Torealizesafecommunicationsinthesafedivingdepthofsubmarines(100m),theinitialincidentangleisrequestedtobenotexceeding26~,andwiththeinitialincidentan~leincreased,thelimitationofwindspeedisdecreased.

  • 标签: IRREGULAR sea surface quantum key distri-aution
  • 简介:OnthebasisofdatacollectedintheJiaozhouBayinJuneandJuly2003,theDICdistributioninseawaterisstudied,andanaverageair-seafluxofCO2isestimated.TheresultsshowthatthecontentofDICinsidethebayismarkedlyhigherthanoutsidethebayinJune,butthecontentofDICoutsidethebayismarkedlyhigherthaninsidethebayinJuly.ThetrendofDICdistributioninsidethebayissimilar,viz.thecontentisthemaximuminthenortheast,thendecreasesgraduallytowardthewest,andthecontentistheminimuminthewest.Thetotaltrendofverticaldistributionistoincreasegraduallyfromsurfacetobottom.ThischaracteristicofDICdistributionisdeterminedbyJiaozhouBayhydrologyandthereisacloserelationbetweenDICandparticulateN,P.AverageCO2fluxacrossthesourceforatmosphericCO2inJuneandJuly,andthetotalCO2fluxfromseawaterintoatmosphereisabout740tinJuneand969tinJuly.

  • 标签: 胶州湾 二氧化碳 密度指示控制器
  • 简介:Experimentalresultsonthethermalcharacteristicsofair-watersprayimpingementcoolingofhotmetallicsurfacearepresentedanddiscussedinthispaper.Thecontrollinginputparametersinvestigatedwerethecombinedairandwaterpressures,platethickness,waterflowrate,nozzleheightfromthetargetsurfaceandinitialtemperatureofthehotsurface.Theeffectsoftheseinputparametersontheimportantthermalcharacteristicssuchasheattransferrate,heattransfercoefficientandwettingfrontmovementweremeasuredandexamined.Hotflatplatesamplesofmildsteelwithdimension120mminlength,120mmbreadthandthicknessof4mm,6mm,and8mmrespectivelyweretested.Theairassistedwaterspraywasfoundtobeaneffectivecoolingmediaandmethodtoachieveveryhighheattransferratefromthesurface.Higherheattransferrateandheattransfercoefficientswereobtainedforthelesseri.e,4mmthickplates.Increaseinthenozzleheightreducedtheheattransferefficiencyofspraycooling.Ataninletwaterpressureof4barandairpressureof3bar,maximumcoolingrates670℃/sandaveragecoolingrateof305.23℃/swereachievedforatemperatureof850℃ofthesteelplate.

  • 标签: 空气压力 金属表面 热特性 水射流 冲击冷却 受控
  • 简介:Theresearchofpropagationcharacteristicsofair-to-watersoundtransmissionisofgreatimportancetothedetectionofaerialtargetsfromunderwater.Inordertostudythepropagationcharacteristicsofair-to-watersoundtransmissioninshallowwater,StateKeyLaboratoryofAcoustics,InstituteofAcoustics,conductedanexperimentintheSouthChinaSeainMarch,2013.Duringtheexperiment,multi-frequencysignalstransmittedbyahooterhungonaresearchshipwerereceivedbyanunderwaterhydrophone,andthedistancebetweenthehooterandthehydrophonewasfrom2.4kmto9.8kmapproximately.Throughanalyzingexperimentaldatainthiswork,theexperimentalair-to-watertransmissionlossatfrequencies128Hzand256Hzisestimatedupto9.8kminrange,anditsoscillationstructureisevident.Thewave-numberintegrationapproachisusedtosimulatetheoreticalair-to-watertransmissionlosses,whichareingoodagreementwithexperimentalvaluesandtoexplaintheexperimentalair-to-watersoundtransmissioncharacteristics.

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  • 简介:Basedontheremotesensingdata,theradiosondedataandprecipitationdataobservedbyweatherstations,distributionsofatmosphericwater-vaporandcloudmotionwindovertheQilianMountainsareanalyzed.Moreover,onthebasisofwater-vaporandcloudmotionwindanalyses,relationsofatmosphericwater-vapordistributionwithprecipitation,atmosphericcirculation,andterrainareinvestigated.Theresultsshowthatdistributionsofatmosphericwater-vaporandprecipitationintheQilianMountainsareaffectedbythewesterlybelt,thesoutherlymonsoon(theSouthAsianmonsoonandplateaumonsoon),andtheEastAsianmonsoon.InthenorthwestQilianMountains,water-vaporandprecipitationaxeentirelyaffectedbythewesterlybelt,andthereisnootherdirectionwater-vaportransportexceptwesterlywater-vaporflux,hence,thenorthwestregionisregardedasthewesterlybeltregion.Inthesouthandmiddleofthemountains,water-vaporismainlycontrolledbythesoutherlymonsoon,37.7%ofthetotalwater-vaporisfromthesouth,especiallyinsummer,thesoutherlywater-vaporfluxaccountsfor55.9%ofthetotal,andfurthermorethewater-vaporcontentinthesoutherlyflowismorethanthatinthewesterlyflow.Thesoutherlymonsoonwater-vaporisinfluencedbytheSouthAsianmonsoonfromtheIndianOceanandtheplateaumonsoonintheQinghai-TibetanPlateau,thus,thesouthandmiddleregioniscalledsoutherlymonsoonregion.ButinthenortheastQilianMountains,theEastAsianmonsoonisthemainclimatesystemaffectingthewater-vapor.Besideswestandnorthwestwater-vaporfluxes,therearealotofeasterlywater-vaporfluxesinsummer.Thefrequencyofeasterlycloudmotionwindsinsummerhalfyearaccountsfor27.1%ofthetotal,thoughthefrequencyisnothigh,itisthemainwater-vaporsourceofsummerprecipitationinthisregion,therefore,thenorthwestregionisamarginalregionoftheEastAsianmonsoon.Ontheotherhand,atmosphericwater-vapor,precipitation,andconversionrateofwater-vaporintopre

  • 标签: 卫星监控数据 祁连山 大气水蒸气 云层
  • 简介:TheaimofthisworkisanimprovementoftheparameterizationofthesoilmoistureintheschemeoftheLandSurfaceProcessModel(LSPM)forapplicationsoverdesertareas.Infact,inverydryconditions,thewatervapourfluxplaysanimportantroleintheevaporationprocessesandinfluencestheundergroundprofilesofhumidityandtemperature.TheimprovedversionofsoilmoistureparametcrizationintheLSPMschemehasbeencheckedbyusingthedatatakenfromthedatabaseofthefieldexperimentHAPEX-Sahel(Hydrology-AtmospherePilotExperimentintheSahel,1990-1992).ModelsimulationsrefertothreedifferentstationslocatedinNiger(Fallow,MilletandTigersites)whereinputdataforLSPMandobservationsweresimultaneouslyavailable.TheresultsofsimulationstakingintoaccountthewatervapourfluxinthesoilmodelLSPM,seemtocomparebetterwiththeobservedbehaviourofsoilmoistureandturbulentheatfluxesthanthoseoverlookingthewatervapourflux,confirmingthegreatimportanceofthewatervapourinsuchdryconditions.

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  • 简介:Effectsofdischargemode,voltageapplied,sizeofthenozzledischargeelectrodeandflowrateofwateronthegenerationofhydroxylradicalwereinvestigatedinairdischargewithatomizedwater,byusingopticalemissionspectroscopy(OES).Waterwasinjectedintothedischargeregionthroughthedischargenozzleelectrode,andalargeamountoffinewaterdrops,formedanddistributedinthedischargeregion,wereobserved.ItwasfoundthatnegativeDCcoronadischargewasmoreeffectivetogeneratethehydroxylradicalsincomparisontopositiveDCcoronadischargeornegativepulseddischarge.Alargerouterdiameterofthenozzleelectrodeorastrongerelectricfieldisbeneficialforhydroxyl-radicalgeneration.Moreover,thereisacriticalvalueintheflowrateofatomizedwateragainstthedischargevoltage.Belowthiscriticalvalue,hydroxyl-radicalgenerationincreaseswiththeincreaseinflowrateofthewater,whileabovethisvalue,itdecreases.Inaddition,itisobservedthatOESfromthedischargeismainlyintheultravioletdomain.Theresultsarehelpfulinthestudyofthemechanismandapplicationofplasmainpollution-controlineitherairorwater.

  • 标签: 羟自由基 放电模式 空气放电 雾化水 光谱测量 光发射
  • 简介:Inthiswork,weperformanumericalstudyofawaterflowoverasteppedspillway.ThisflowisdescribedbytheReynoldsaveragedNavier-Stokesequation(RANS)associatedwiththeturbulencek-εmodel.Theseequationsaresolvedusingacommercialsoftwarebasedonthefinitevolumeschemeandanunstructuredmesh.Theair-waterflowwasmodeledusingvolumeoffluid(VOF)andmultiphasicmethods.Thecharacteristicsoftheflowwereinvestigatedincludingthetotalpressure,thevelocityprofile,etc..Weanalyzetheeffectsontheflowstructureofthestepsandcountermarchinclination,theairinjectionthroughthecountermarchintothewaterflowandthedynamicswaterdischarges.Resultsshowthattheinclinationofthecountermarchrelativetotheverticalandtheairinjectionintothewaterflowincreasethetotalpressureintheneighbourhoodofthesteps.

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  • 简介:Dielectricbarrierdischarge(DBD)excitatedbypulsedpowerisapromisingmethodforproducingnonthermalplasmaatatmosphericpressure.DischargecharacteristicinaDBDwithsaltwateraselectrodesbyahome-madeunipolarnanosecond-pulsepowersourceispresentedinthispaper.Thegeneratoriscapableofprovidingrepetitivepulseswiththevoltageupto30kVanddurationof70nsata300Ωresistiveload.Appliedvoltageanddischargecurrentaremeasuredundervariousexperimentalconditions.TheDBDcreatedbetweentwoliquidelectrodesshowsthatthedischargeishomogeneousanddiffuseinthewholedischargeregime.Spectradiagnosisisconductedbyanopticalemissionspectroscopy.Theairplasmahasstrongemissionfromnitrogenspeciesbelow400nm,notablythenitrogensecondpositivesystem.

  • 标签: 常压等离子体 空气等离子 脉冲电源 水电极 纳秒 介质阻挡放电
  • 简介:空气鈥攕e的过程新鲜的水交换在在大气的科学和地球物理的液体动力学(LASG)的国家重点实验室开发的全球鈥?海洋鈥擜tmosphere陆地鈥擲y茎模型成功地被包括。联合集成的结果证明气候飘移成功地被控制了。在对表面的变化的海洋循环的回答上分析新鲜的水或在为咸度的流动状况下面的海洋旋转起来阶段是由空至海的新鲜的水流动联合的实现的关键的咸度强迫表演。这研究也证明nthly,omaly联合计划(MMFA)的鈥擣lux鈥擜n由于和张(1998)向前带了的修改鈥擬o对每日的空气鈥攕e合适不仅联合而且为每日的新鲜的水流动联合的热流动。关键词新鲜的水流动-由空至海的联合-Thermohaline循环这个工作被国家关键工程(资助No.96-908-02-03)共同支持,优秀国家关键实验室研究工程(资助No.49823002)和在资助鈥?白·仁·吉·胡亚下面的中国科学院(CAS)?为联合气候模型鈥的鈥淰alidation?

  • 标签: FRESH water flux AIR-SEA COUPLING THERMOHALINE
  • 简介:AvisualizedinvestigationwascarriedoutontheeffectofthedivergingangleonthebubblemotionandinterfacialbehaviorinaVenturi-typebubblegenerator.Itwasfoundtwoorthreelargevortexesformedinthedivergingsection,resultinginstrongreentrantjetflowinthefrontofthebubblesorslugsrushingoutofthethroat.Thejetflowinreturnbumpsintotheongoingbubblesorslugs,leadingtostronginteractionbetweenthegasandliquidphases.Thediverginganglehassignificantinfluenceonthereentrantflowprocessandtheperformanceofthebubblegeneratoraswell.Increasingthedivergingangleresultsinthereentrantflowmovingfurtherforwardtotheupstreamandintensifiestheinteractionbetweenthetwophases.Asaconsequence,thebreakuporcollapseofbubblesbecomesmoreviolent,wherebyfinerbubblesaregenerated.Assuch,thereentrantflowstronglylinkstotheperformanceoftheVenturichanneltakenasabubblegenerator,andthatamoderateincreaseinthediverginganglecanimproveitsperformancewithoutadditionalincreaseinflowresistancelikethatbyincreasingliquidflowrate.

  • 标签: VENTURI CHANNEL REENTRANT jet flow process
  • 简介:Insituphotochromicprocessinthemonolayerofaphotochromicspiropyranderivativewithoutlongalkylchain,wasinvestigated.Thephotochromismattheair/waterinterfaceunderdiffernetsurfacepressureswasstudiedbysurfacepressure-areaisotherms,surfacepressure-timecurves,area-timecurvesandBrewsteranglemicroscopy.Bothformsofthecompoundwerefoundtoformmonolayersattheair/waterinterfacealthouhgitdoesnothavelongalkylchain.Alargeareaexpansioninthemonolayercorrespondingtoazreo^thorderreactionwasfoundattheinitialstageoftheUVlightirradiation.Aseriesofdynamicinvestigationsrevealedthatathighpressureafterphasetransitioninthemonolayer,thesurfacepressurechangesgreatlyumderalternativeirradiationofUVandvisiblelight.Anobviousmorphologicalchangeaccompanyingwiththephotochromismwasobservedinsitu.

  • 标签: 空气/水界面 光致变色 螺吡喃 朗缪尔单分子层
  • 简介:Wedescribeafewmathematicaltoolswhichallowtoinvestigatewhetherair-waterinterfacesexist(underprescribedconditions)andaremechanicallystableandtemporallypersistent.Intermsofphysics,air-waterinterfacesaregovernedbytheYoung-Laplaceequation.Mathematicallytheyaresurfacesofconstantmeancurvaturewhichrepresentsolutionsofanonlinearellipticpartialdifferentialequation.Althoughexplicitsolutionsofthisequationcanbeobtainedonlyinveryspecialcases,itis-undermoderatelyspecialcircumstances-possibletoestablishtheexistenceofasolutionwithoutactuallysolvingthedifferentialequation.Wealsoderivecriteriaformechanicalstabilityandtemporalpersistenceofanairlayer.Furthermorewecalculatethelifetimeofanon-persistentairlayer.Finally,weapplythesetoolstotwoexampleswhichexhibitthesymmetriesof2Dlattices.TheseexamplescanbeviewedasabstractionsofthebiologicalmodelrepresentedbytheaquaticfernSalvinia.

  • 标签: interfaces air LAYERS differential geometry stability
  • 简介:Electro-hydraulicimpulsewater-airmixingjetbywhichthequalityofmetalmaterialscanbeimprovedisdescribedinthispaper.Theexperimentalresultsprovedthatthehardnessandthemicro-hardnessofthesurfacelayerofmetalmaterialscanbeimprovedwiththismethod,forexample,themicrohardnessofCrWMncanbeincreasedby35.62percent.

  • 标签: 空气 两相流 金属材料 表面性质 机械强度