学科分类
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21 个结果
  • 简介:Offshoredrillingandproductionoperationscanresultinspillsorleaksofhydrocarbonsintoseabedsediments,whichcanpotentiallycontaminatethesesedimentswithoil.Ifthisoillatermigratestothewatersurfaceithasthepotentialfornegativeenvironmentalimpacts.Forpropercontingencyplanningandtoavoidlargerconsequencesintheenvironment,itisessentialtounderstandmechanismsandratesforhydrocarbonmigrationfromoilcontainingsedimentstothewatersurfaceaswellashowmuchwillremaintrappedinthesediments.Itisbelievedthattheamountofoiltransportedoutofthesedimentcanbeaffectedbytidalpumping,acommonformofsubterraneangroundwaterdischarge(SGD).However,wecouldfindnostudyexperimentallyinvestigatingthephenomenonoffluidflowinsubseasedimentscontainingoilandtheeffectsoftidalpumping.Thisstudypresentsanexperimentalinvestigationoftidalpumpingtodetermineifitisapossiblemechanismthatmaycontributetotheappearanceofanoilsheenontheoceansurfaceaboveasedimentbedcontainingoil.AnexperimentalapparatuswasconstructedofclearPVCpipeallowingforoilmigrationtobemonitoredasitflowedoutofasandpackcontainingoil,whiletidalpressureoscillationswereappliedinthreedifferentmanners.Theeffectoftidalpumpingwassimulatedviacompressionofairabovethewater(whichsimulatedtheincreasingstaticheadfromtidalexchange).Experimentalresultsshowthatsustainedoilreleaseoccurredfromalltests,andtestswithoscillatingpressureproducedforlongerperiodsoftime.Furthermore,theexperimentalresultsshowedthattheoilmigrationratewasaffectedbygrainsize,oilsaturation,andoscillationwavetype.Inalloscillatingexperimentstherateandultimaterecoverywaslessthanthecomparablestaticexperiments.Fortheconditionsstudied,theexperimentalresultsindicatethatwithanoscillatingpressureontopofasandpack,movementofanon-replenishingsourceofoilissuppressed

  • 标签:
  • 简介:我们实现在我们87Rb空间寒冷原子钟,它在单程的模式操作。几修正在我们的以前的物理、光的系统上被做。在最高的察觉地区的有效原子信号与87%被增加到2.5次抽效率。冷原子云的温度被1.4K增加。我们在抽的激光紧张和detuning上学习有效信号获得和抽的效率的依赖。转变的效果被讨论。这种技术可以在未来空间寒冷原子钟被使用。

  • 标签: 冷原子钟 制备 光泵 原子空间 泵浦效率 光学系统
  • 简介:TheStokesspectruminthestimulatedRamanscattering(SRS)isverycomplicated.Inthisarticle,weusebothGaussianandLorentzapproximationtoinvestigatethegainpropertiesofmulti-pumpingbroadbandRamanamplifier,andpresentsomeschemesforflatteningthegain.Alltheresultsshowthattheflatnessofthegainspectrumiscloselyrelatedtothepumpingfrequencygrid.ByresearchingthegainpropertiesofRamanamplifiersofsuchITU-TfibersasG.652,G.653,G.655andlargeeffectiveareanon-zerodispersionflatteningfiber,wefindthattheRamangainisassociatedwiththefibertypeanditstransmissioncharacteristics,especiallyitdecreaseswiththeincreaseoftheeffectivecorearea.

  • 标签: 光纤通信 多波长抽运 RAMAN放大器 SRS
  • 简介:Comparedwithendpumpingfibercombiner,oneoftheadvantagesforsidepumpingcombineristheunlimitedpumpingpoints,whichmeansmulti-pointorcascadedsidepumpingcanberealized.However,thelossmechanismofthecascadedstructureisrarelydiscussed.Inthispaper,wepresentthenumericalandexperimentalinvestigationaboutthelossmechanismofatwo-stage-cascadedsidepumpingcombinerbasedontapered-fusedtechnique.Theinfluenceoflossmechanismonthecouplingefficiencyandthermalloadofthefibercoatingisanalyzedaccordingtosimulationsandexperimentswithdifferenttaperingratiosforthefirststage.Basedontheanalysis,acascadedcomponentwithtotalpumpcouplingefficiencyof96.4%handlingapumppowerof1088Wisachievedbyemploying1018nmfiberlaserasthepumpsource.Futureworktofurtherimprovetheperformanceofacascadedsidepumpingcombinerisdiscussedandprospected.

  • 标签: FIBER COMBINER FIBER laser SIDE PUMPING
  • 简介:Itispresentedthatthereisapumpingeffectatitsbaseinthedevelopmentprocessofacumulus.Inthestrongeststageofcumulusdevelopment,thepumpingismainlyproducedbythebuoyanceatthebase,andmaybetakenasthefirstapproximationoftheascendingspeedatthebase.Theresultsofnumericalcalculationsandsimulationsoffourobservedradarechoesshowthatasthefirstapproximation,theheightofair-masscumulusmaybesimulatedbyHaltinermodelintheabsenceofob-servedascendingspeedsatthebase,andtheHaltinermodelcanbecharacterizedbythesensitivityofthecumulusdevelopmenttothevirtualtemperatureexcessoverenvironmentatthebase.

  • 标签: PUMPING ascending EXCESS lifting distinguished adding
  • 简介:A2-DLatticeBoltzmannMethod(LBM)coupledwithaSub-GridStress(SGS)modelisproposedandvalidatedbyflowsaroundanon-submergedspurdikeinachannel.AndthentheLBM-SGSmodelisfurtherappliedtoflowsinapumping-stationforebay.ShallowwaterequationsarenumericallysolvedbytheLBMandtheturbulencecanbetakenintoaccountandmodeledefficientlybytheLargeEddySimulation(LES)model.Thebounce-backschemeofthenon-equilibriumpartofthedistributionfunctionisusedattheinletboundary,thenormalgradientofthedistributionfunctionissetaszeroattheoutletboundaryandthebounce-backschemeisappliedtothesolidwalltoensurenon-slipboundaryconditions.Firstly,themodelsuccessfullypredictstheflowcharacteristicsaroundaspurdike,suchascirculatingflow,velocityandwaterdepthdistributions.TheresultsareverifiedbytheexperimentaldataandcomparedtotheresultsobtainedbyconventionalSmagoringskyModel(SM)ofLES.Finally,theLBM-SGSmodelisusedtofurtherpredicttheflowcharacteristicsinaforebay,suchassecondaryflowandwaterlevel.Thecomparisonsshowthatthemodelschemehasthecapacitytosimulatecomplexflowsinshallowwaterwithreasonableaccuracyandreliability.

  • 标签: SGS模型 流动特性 抽水站 制程 加工 雷射
  • 简介:ThewaveCoriolis-Stokes-Force-modifiedoceanmomentumequationsarereviewedinthispaperandthewaveStokestransportispointedouttobepartoftheoceancirculations.UsingtheEuropeanCentreforMedium-RangeWeatherForecasts40-yearreanalysisdata(ERA-40data)andtheSimpleOceanDataAssimilation(SODA)version2.2.4data,themagnitudeofthistransportiscomparedwiththatofwind-drivenSverdruptransportanda5-to-10-precentcontributionbythewaveStokestransportisfound.Bothtransportsarestrongerinborealwinterthaninsummers.Thewaveeffectcanbeeithercontributionorcancellationindifferentseasons.ExaminationwithKuroshiotransportverifiessimilarseasonalvariations.Theclarificationoftheefficientwaveboundaryconditionhelpstounderstandtheroleofwavesinmasstransport.Itactsassurfacewindstressandcanbefunctionaldowntothebottomoftheageostrophiclayer.Thepumpingvelocitiesresultingfromwave-inducedstressarezonallydistributedandaresignificantinrelativelyhighlatitudes.Furtherworkwillfocusonthemodelperformanceofthewave-stress-changed-boundaryandtheroleofswellsintheeasternpartoftheoceans.

  • 标签: 海洋环流 运输 大众 季节性变化 流通 数值天气预报
  • 简介:BackgroundThrombocytopeniaisacommoncomplicationofIABP.Untilnow,thereisnounifiedconclusionsabouttheincidence,characteristics,riskfactorsandtheprognosisofIABPrelatedthrombocytopenia.MethodsInthisstudy,thedataofpatientswithACSundergoingPCIandIABPwereretrospectivelyanalyzed.Allenrolledpatientsweredividedintothrombocytopeniagroupandnon-thrombocytopeniagroupaccordingtotheoccurrenceofthrombocytopeniaafterinsertionofIABP.Thebaselinedataofthetwogroupswerecompared,andthepossibleriskfactorsofthrombocytopeniaandtheirimpactonprognosiswereanalyzedbychi-squaretestandlogisticregressionanalysis.ResultsSixty-twopatientswereenrolledinthisstudy.TherateofIABPassociatedthrombocytopeniawas25.8%(16/62)ofallpatients.OlderagewasanindependentriskfactorofIABPassociatedthrombocytopenia(OR:3.625;95%confidenceinterval:1.016-12.935;P=0.047).TheincidenceofTIMIbleedingeventswashigherinthrombocytopeniagroup[75.0%(12/16)vs.43.5%(20/46),P=0.042].Therateofin-hospitaldeathwassimilarbetweenthetwogroups[18.8%(3/16)vs.17.4%(8/46),P=1.0].ConclusionIABPassociatedthrombocytopeniaoccursin25.8%ofpatientswithACSundergoingPCIandcorrelateswithincreasedTIMIbleedingevents.OlderagemaypredictIABPassociatedthrombocytopenia.

  • 标签: acute coronary syndrome intra-aortic BALLOON PUMPING
  • 简介:RelativerolesofEkmantransportandEkmanpumpingindrivingsummerupwellingintheSouthChinaSea(SCS)areexaminedusingQuikSCATscatterometerwinddata.ThemajorupwellingregionsintheSCSarethecoastalregionseastandsoutheastofVietnam(UESEV),eastandsoutheastofHainanIsland(UESEH),andsoutheastofGuangdongprovince(USEG).ItisshownthattheEkmantransportduetoalongshorewindsandEkmanpumpingduetooffshorewindstresscurlplaydifferentrolesinthethreeupwellingsystems.InUESEV,EkmanpumpingandEkmantransportareequallyimportantingeneratingupwelling.TheEkmantransportincreaseslinearlyfrom0.49SvinMayto1.23SvinAugust,whiletheEkmanpumpingincreasesfrom0.36to1.22Svduringthesameperiod.InUESEH,themeanestimatesofEkmantransportandEkmanpumpingare0.14and0.07Sv,respectively,indicatingthat33%ofthetotalwind-drivenupwellingisduetoEkmanpumping.InUSEG,themeanEkmantransportis0.041SvwiththepeakoccurringinJuly,whileEkmanpumpingismuchsmaller(0.003onaverage),indicatingthattheupwellinginthisareaisprimarilydrivenbyEkmantransport.Inthesummersof2003and2007followingElNio-SouthernOscillation(ENSO)events,bothEkmantransportandEkmanpumpingdecreaseinUESEVduetotheabnormallyweaksouthwestmonsoon.Duringthesameevents,however,EkmantransportisslightlyenhancedandEkmanpumpingisweakenedinUESEHandUSEG.

  • 标签: 交通运输 中国南海 EKMAN抽吸 海上 夏季 驱动
  • 简介:backgroundToinvestigatetheeffectofintra-aorticballoonpumping(IABP)onno-reflowphenomenoninprimarypercutaneouscoronaryintervention(PCI)forST-ElevationMyocardialInfarction(STEMI).MethodsClinicaldataof22acutemyocardialinfarctionpatientsafterPCIwithangiographicno-reflowphenomenonwereretrospectivelyanalyzedbetweenJanuary2006andDecember2009.12patientsunderwentIABP,other10patientsascontrolgroup.Weobserveddifferenceofcardiacstructure,brainnatriureticpeptide(BNP)andventricularsystolicfunctionbetweentwogroup,aswellascardiacinjurymarkers(MYO,CK-MB,cTnI)inbothgroupsonthedaysof1,2,3,5,7,10afterthedifferentinterventions.Inaddition,cardiacstructureandventricularsystolicfunctionincludingleftatriummedialdiameter(LAMD),leftventricularmedialdiameter(LVMD),leftventricularejectionfraction(LVEF)wasevaluatedafter10days,3months,6months.Finally,statisticswasusedtoanalysisthedata.ResultsTheseveralvasoactivesubstancesaswellascardiacinjurymarkersandLAMD,LVMD,LVEFof10days,3months,6monthsofIABPgroupweresignificantdifferencewithcontrolgroup(P<0.05).BNPtargetsofIABPgroupcomparedwiththecontrolgroupnosignificantdifference(P>0.05).ConclusionsIABPhaseffectsonprognosisinSTEMIpatientswhoperformedPCIwithangiographicno-reflowphenomenon,whichisconducivetorecoveryofheartfunction.

  • 标签: PCI 主动脉 球囊 急性心肌梗死 心脏结构 应用
  • 简介:Steelproductionremainsanenergy-intensiveindustryinaworldwherethereisanever-increasingemphasisonloweringenergycosts,reducinggreenhousegasemissions,ensuringenvironmentalcompliance,andimprovingproductionrates.Asthegrowthindemandforspecialitysteelscontinuesitssteadyincrease,andnewmarketopportunitiesforeverhighersteelperformanceappear,significantglobalattentionisfocusedonsecondarysteelprocessing,andontheVD,VODandRHprocesses.Onenewtechnologyisabletoaddressalloftheseissuesandconcernstogether-theintegratedladletankvacuumdegassingstationequippedwiththenewmodularmechanicalvacuumpumpingsystems.Thispaperwillexaminetheeconomicandenvironmentalbenefits,operationalcharacteristics,andrecentresultsprovidedbysuchsteeldegassinginstallations.

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  • 简介:Anall-fiberizedandnarrow-bandwidthmasteroscillatorpoweramplification(MOPA)systemwithrecordoutputpowerof4kWlevelandslopeefficiencyof78%isdemonstrated.Tandempumpingstrategyistentativelyintroducedintothenarrow-bandwidthMOPAsystemforthermallyinducedmodeinstability(TMI)suppression.ThestimulatedBrillouinscattering(SBS)effectisbalancedbysimplyusingone-stagephasemodulationtechnique.Withdifferentphasemodulationsignals,SBSlimitedoutputpowersof336W,1.2kWand3.94kWarerespectivelyachievedwithspectralbandwidthsaccountingfor90%powerof~0.025,0.17and~0.89nm.Comparedwithourprevious976nmpumpingsystem,TMIthresholdisoverallboostedtobe>5timesinwhichtandempumpingincreasestheTMIthresholdof>3times.Thebeamquality(M~2factor)oftheoutputlaseriswellwithin1.5belowtheTMIthresholdwhileitisultimatelysaturatedtobe1.86withtheinfluenceofTMIatmaximaloutputpower.ExceptforSBSandTMI,stimulatedRamanscattering(SRS)effectwillbeanotherchallengeforfurtherpowerscaling.InsuchahighpowerMOPAsystem,multidetrimentaleffects(SBS,SRSandTMI)willcoexistandmaybemutual-coupled,whichcouldprovideawellplatformforfurthercomprehensivelyinvestigatingandoptimizingthehighpower,narrow-bandwidthfiberamplifiers.

  • 标签: advanced LASER technology and APPLICATIONS design
  • 简介:TheaveragepoweroffiberlasershasbeenscaleddeeplyintothekWregimeinthepastyears.However,stimulatedRamanscattering(SRS)isstillamajorfactorlimitingfurtherpowerscaling.Here,wehavedemonstratedforthefirsttime,tothebestofourknowledge,thesuppressionofSRSinahalf10kWtandempumpingfiberamplifierusingchirpedandtiltedfiberBragggratings(CTFBGs).Withspeciallyself-designedandmanufacturedCTFBGsinsertedbetweentheseedlaserandtheamplifierstage,amaximumSRSsuppressionratioof>15dBinspectrumisobservedwithnoreductioninlaserefficiency.WithoneCTFBG,theeffectiveoutputpowerisimprovedto3.9kWwithabeamqualityM2factorof~1.7from<3.5kWwithanM2factorof>2;withtwoCTFBGs,theeffectivelaserpowerreaches4.2kWwithanincreasingratioof20%andanM2factorof~1.8,andfurtherpowerimprovementislimitedbythepowerandperformanceofthe1018nmpumpsources.ThisworkprovidesaneffectiveSRSsuppressionmethodforhigh-powerall-fiberlasers,whichisusefulforfurtherpowerscalingofthesesystems.

  • 标签: EFFECTIVE stimulated Raman 10 KW
  • 简介:40-GHzclockmodulatedsignalasapumptoimprovetheefficiencyoffour-wavemixing(FWM)-basedwavelengthconversionina26.5-kmdispersionshiftedfiber(DSF)isinvestigated.TheexperimentalresultsdemonstratethattheconjugatedFWMcomponenthashigherintensitywiththeclockpumpingthanthatwiththecontinuous-wave(CW)lightpumping.TheimprovementofFWM-basedwavelengthconversionefficiencyisnegligiblewhenthepumppowerislessthanBrillouinthreshold.ButwhenthepumppowerisgreaterthanBrillouinthreshold,theimprovementbecomessignificantandincreaseswiththeincrementofpumppower.Theimprovementcanincreaseupto9dBifpumppowerreaches17dBm.

  • 标签: 四波段 波长 色散 光纤