学科分类
/ 5
90 个结果
  • 简介:Thispaperfocusesontheflowcharacteristicandlocalresistanceofnon-Newtonianpowerlawfluidinacurved90°bendpipewithcircularcross-sections,whicharewidelyusedinindustrialapplications.Byemployingnumericalsimulationandtheoreticalanalysisthepropertiesoftheflowandlocalresistanceofpowerlawfluidunderdifferentworkingconditionsareobtained.ToexplorethechangeruletheexperimentiscarriedoutbychangingtheReynoldsnumber,thewallroughnessanddifferentdiameterratioofelbowpipe.ThevariationofthelocalresistancecoefficientwiththeReynoldsnumber,thediameterratioandthewallroughnessispresentedcomprehensivelyinthepaper.TheresultsshowthatthelocalresistanceforcecoefficienthardlychangeswithReynoldsnumberofthepowerlawfluid;thewallroughnesshasasignificantimpactonthelocalresistancecoefficient.Asthepipewallroughnessincreasing,thecoefficientoflocalresistanceforcewillincrease.Themainreasonoftheinfluenceoftheroughnessonthelocalresistancecoefficientistheincreaseoftheeddycurrentregioninthepowerlawfluidflow,whichincreasesthekineticenergydissipationofthemainflow.Thispaperprovidestheoreticalandnumericalmethodstounderstandthelocalresistancepropertyofnon-Newtonianpowerlawfluidinelbowpipes.

  • 标签: 非牛顿幂律流体 局部阻力系数 弯管 壁面粗糙度 雷诺兹数 流动特性
  • 简介:Heathandlinghasbeenasignificantproblemofthehighpowerfiberlasersystemsastheoutputpowerincreasesrapidly.Claddingpowerstripper(CPS)whichisusedtodealwiththeunwantedopticalpowerandlightisrequiredforhighercoolingability.Sothemethodsofstrippingtheunwantedlightattractedmuchattentionrecently,andthethermaleffectisgiven.However,fewinvestigationsfocusonthedissipationoftheheatconvertedfromtheunwantedlight.Inthispaper,anapproachofactivecoolingforCPSisdemonstrated.ThisisachievedbyusingmicrochannelcoolingtechnologyinheatsinkinginCPStoimprovetheefficiencyofheatexchange.InordertoexplainthemechanismofCPSthefunctionofitandconsistenceofcategoriesoftheunwantedlightaredetailedfirstly.Thenmicrochannelheatsinkingisproposedandverifiedbytheheatexchangetheory.Atlast,thedesignoftheCPSwithmicrochannelheatsinkingisshownandfollowingexperimentisconducted.Thefinaltemperatureofthedevicewith1000WcladdingpowerwasdemonstratedatlasttoverifytheabilityofheatdistributionoftheCPScomponent.ThissuggeststhattheseCPSscanbeusedtostripeathousandofwattsoflightinhighpowerdoublecladdingfiberlasers.

  • 标签:
  • 简介:Atypeofnovelinverterpowersupplysystemforhigh-powertwin-wirepulsedgasmetalarcwelding(GMAW)ispresentedmainlyfordealingwiththedisadvantagesoftheconventionalpowersupplyfortwin-wirepulsedGMAWofwhichtheoutputpowerisgenerallydifficulttoincreaseduetolimitationsofthepowerofsemiconductorsandthepowerdensityofmagneticdevices.Inthepowersuppliesforthemasterandslavearcs,thedigitalsignalprocessor(DSP)TMS320F28335isusedtoformtheDSP-basedsynergiccontrolsystemforparallelhigh-powerpulsedGMAW,whichachieveshigh-poweroutputoftwoparallelinverterscontrolledbyasingleDSP;master-slavecommunicationisachievedbyusingecontrollerareanetwork(eCAN)moduleofDSP,thusrealizinganti-phasepulseoutputofhigh-powertwin-wirepulsedGMAWandreducingtheinterferencebetweentwinarcs.Theexperimentresultsdemonstratethatthedesignedinverterpowersupplysystemforhigh-powertwin-wirepulsedGMAWcanbringabouthigh-powerefficiencyofwelding,stableweldingprocessandproperformationofwelds.

  • 标签: 脉冲熔化极气体保护焊 逆变电源系统 GMAW焊 大功率脉冲 双丝 DSP控制
  • 简介:Wepresenttheworkflowofthedesign,realizationandtestingofdeformablemirrorssuitableforhighpowerdiodepumpedsolid-statelasers.Itstartswiththestudyoftheaberrationtobecorrected,andthenitcontinueswiththedesignoftheactuatorspositionandcharacteristic.Inthispaper,wepresentandcomparethreedeformablemirrorsrealizedformulti-Jlevellaserfacilities.Weshowthatwiththesamedesignconceptitispossibletorealizedeformablemirrorsforothertypesoflasers.Asanexample,wereporttherealizationofadeformablemirrorforfemtosecondlasersandforaCWCO2laser.

  • 标签: ADAPTIVE OPTICS CLOSED LOOP deformable MIRROR
  • 简介:Whenexposedtointenseelectromagneticfields,thequantumvacuumisexpectedtoexhibitpropertiesofapolarizablemediumakintoaweaklynonlineardielectricmaterial.Variousschemeshavebeenproposedtomeasuresuchvacuumpolarizationeffectsusingacombinationofhigh-powerlasers.Motivatedbyseveralplannedexperiments,weprovideanoverviewofexperimentalsignaturesthathavebeensuggestedtoconfirmthispredictionofquantumelectrodynamicsofrealphoton–photonscattering.

  • 标签: Heisenberg–Euler photon–photon scattering VACUUM BIREFRINGENCE VACUUM
  • 简介:Non-lineardynamics,fractals,periodicoscillations,bifurcations,chaos,andotherterminologieshavebeenusedtodescribehumanbiologicalsystemsintheliteratureforafewdecades.Theeightmanuscriptsincludedinthisspecialissuediscussedthehistoricalbackground,selectedtheoretical

  • 标签: 非线性动力学 动态世界 周期振荡 生物系统 分岔 混沌
  • 简介:In2016,thepowersupplyinCSRmwasdigitalizedtofurtherimprovethereliabilityofoperation.Anewvectorrecticationtechniqueisdevelopedfortheresearchofadvancedpowersupplyandelectricalrelatedtechnologies.AnumberofEMCandelectricalsafetytestingitemsforHIMMWuweipowersupplieshasbeencompleted.DigitalizationupgradeofthepowersupplyCSRmpowersupply,including30setsquadrupolemagnetpowersupply,6setssextupolemagnetpowersupplyand8setsbipolarcorrectmagnetpowersupply,weretransformedbyusingofdigitalcontrollersbasedonFPGA.Fig.1displaysthemeasurementresultsofthenewdigitalpowersupplyofquadrupolemagnet,thecurrenterror(attop)was1.7610?5,thetrackinger-rorwas5.2810?5.Theperformanceandreliabilityofthepowersupplyhavebeengreatlyimproved.

  • 标签:
  • 简介:三桶、四桶近海有转移力量的结构的一种新形式的风力量基础在这被建议纸,和foundation-soil-transition结构的综合有限元素模型被使用ABAQUS建立。建议基础的带的能力在垂直负担,水平负担和弯曲时刻下面被学习。多斗式的基础的垂直适用能力能被垂直适用能力粗略地估计,这能被看见单个桶;三桶的基础计划的水平适用能力被排水量控制,当四桶的基础计划的被土壤的内部力量控制时。而且,带的能力被形成由的全面结构提供在土壤前多斗式失败。与常规单个桶的基础相比,主要有紧张和压力,被用于多斗式的基础,以便基础的带的能力能充分被利用。土壤失败的概率能很好与建议多斗式的基础被减少,并且转移力量的结构的压力传播通过有可变剖面图的钢横梁是更一致的。

  • 标签: 天津大学学报 英文版
  • 简介:Laserdriversareanenablingfactortoinertialconfinementfusion,becauselaserdiodesmustbeusedinsteadofflashlamps.Wediscussthelimitationsoflaserdiodearraysandshowwhatstepstheindustryistaking.Thepumppowerrequirementsoflarge-scaleprojectssuchasLIFEorHiPERarewithinreachofsemiconductorlaserdiodeassemblies.Pulsedlightoutputpowersperlaserbarshavebeenaround300Wperbar,asintheJenoptik940nmbarspreviouslyusedforpumpingtheYb:YAGslabsintheDiPOLEproject.Byredesigningthesemiconductorlaserstructures500Wperbarisnowcommerciallyavailablefor808,880and940nmpumpwavelengths.Theconstructionofoneinertialfusionpowerplantwillrequireanamountofsemiconductorlaserchipsinexcessofthecurrentannualproductionbytwoordersofmagnitude.Thisaddstotheengineeringtaskofimprovingthedevicecharacteristicsachallengetoproductioncapacity.Whiletheindustrybenefitsfromtherecentboostinsolid-statelightingthatactsasatechnologydriver,cooperationbetweenmanufacturerswillbeimperative,andtothisendweproposestandardizationefforts.

  • 标签: DIODE pumped DPSSL HIGH-ENERGY class IFE
  • 简介:Inmanydomainsofphysics,methodsfordealingwithnon-perturbativeaspectsarerequired.Here,IwanttoarguethatagoodapproachforthisistoworkontheBoreltransformsofthequantitiesofinterest,thesingularitiesofwhichgivenon-perturbativecontributions.ThesesingularitiesinmanycasescanbelargelydeterminedbyusingthealiencalculusdevelopedbyJeanEcalle.Mymainexamplewillbethetwopointfunctionofamasslesstheorygivenasasolutionofarenormalizationgroupequation.

  • 标签: Schwinger-Dyson equations SERIES resommation ALIEN CALCULUS
  • 简介:Alow-thresholdRamaneffectinakilowattytterbium-dopednarrowbandfiberamplifiersystemisreported.TheRamanStokeslightat1120nmisachievedwiththetotaloutputpowerofonly~400W,indicatingthattheRamanthresholdofthiskilowattcodirectionalpumpedcontinuouswavefiberamplifierismuchlowerthanthepredictedvalueestimatedbytheclassicformula.Tofigureoutthemechanismofthisphenomenon,simulationsbasedonthegeneralstimulatedRamanscattering(SRS)modelareanalyzedindicatingthatthekeyfactoristhecouplingbetweenfour-wavemixing(FWM)andSRS.Thesimulationresultsareingoodagreementwithourexperiments.

  • 标签: 光纤放大器 拉曼效应 低阈值 窄带 高功率 受激拉曼散射
  • 简介:Anon-intrusivedesignformonitoringeverydayactivitiesofanelderlypersonispresented.Theproposedsystemisintendedtobeusedinthebedroom,allowingtheelderstostayathomeinasafeenvironment.Therequiredhardwaredesignissimpleinstructureandcosteffective.ThesensordesignisimplementedbyusingcapacitivesensorsandanArduinomicrocontrollerunit.Andarealtimegraphicaluserinterfaceisimplementedtomonitortheelderlyperson.Theperformanceanalysisshowsthatthesensordesignisabletodifferentiatebetweenahumanbodyandahousepet.

  • 标签: 室内环境 侵入性 行为活动 监测 电容式传感器 硬件设计
  • 简介:A2-DdepthaveragedRNGk-εmodelisdevelopedtosimulatetheflowinatypicalreachoftheUpperYellowRiverwithnon-monotonicbanks.Inordertotakeaccountoftheeffectofthesecondaryflowinabend,themomentumequationsaremodifiedbyaddinganadditionalsourceterm.Acomparisonbetweenthenumericalsimulationandthefieldmeasurementsindicatesthattheimproved2-DdepthaveragedRNGk-εmodelcanimprovetheaccuracyofthenumericalsimulation.Anarcsplineinterpolationmethodisdevelopedtointerpolatethenon-monotonicriverbanks.Themethodcanalsobereasonablyappliedforthe2-Dinterpolationoftheriverbedlevel.Throughacomparisonofthewatersurfacegradientssimulatedinthesevenbendsofthestudiedreach,someanalyticalformulaeareimprovedtoreasonablycalculatethelongitudinalandtransversegradientsinmeanderingriverreaches.Furthermore,thepositionsofthemaximumwaterdepthandthemaximumvelocityinatypicalbendarediscussed.

  • 标签: 黄河上游 非单调 数值研究 银行 k-ε模型 样条插值法
  • 简介:Wedemonstrateadiode-pumpTm3+t-dopedall-fiberlaseroperatingat1908nmbasedonamasteroscillatorpoweramplifier(MOPA)configuration.Inourwork,152Woflaseroutputpowerisgeneratedbyatotalincidentpumppowerof434Wat790nm,correspondingtothetotalopticalefficiencyof35%.Thelaserwavelengthis1908.29nm.Tothebestofourknowledge,itisthehighestoutputpowerreachedaround1908nmwithsuchanarrowlinewidthof0.18nmbasedonaMOPAconfiguration.

  • 标签: 全光纤激光器 功率放大器 主振荡器 配置 光谱线宽 TM
  • 简介:Withthedevelopmentofsmartgrid,residentshavetheopportunitytoscheduletheirhouseholdappliances(HA)forthepurposeofreducingelectricityexpensesandalleviatingthepressureofthesmartgrid.Inthispaper,weintroducethestructureofhomeenergymanagementsystem(EMS)andthenproposeapoweroptimizationstrategybasedonhouseholdloadmodelandelectricvehicle(EV)modelforhomepowerusage.Inthisstrategy,theelectricvehiclesarechargedwhenthepriceislow,andotherwise,aredischarged.Byadoptingthiscombinedsystemmodelunderthetime-of-useelectricityprice(TOUP),theproposedschedulingstrategywouldeffectivelyminimizetheelectricitycostandreducethepressureofthesmartgridatthesametime.Finally,simulationexperimentsarecarriedouttoshowthefeasibilityoftheproposedstrategy.Theresultsshowthatcrossovergeneticparticleswarmoptimizationalgorithmhasbetterconvergencepropertiesthantraditionalparticleswarmalgorithmandbetteradaptabilitythangeneticalgorithm.

  • 标签: EMS smart grid scheduling space state of charge time-of-use electricity price vehicle-to-grid technology(V2G) technology