学科分类
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40 个结果
  • 简介:Theβ-decaysofneutron-richcarbon,nitrogenandfluorineisotopeshavebeensys-tematicallystudiedusingtheOXBASHshellModel.Inthepsd,spsdandspsdpfmodelspace,weusetheWBPinteractiontocalculatethehalf-livesandneutronemissionprobabilitiesofneutron-richcarbonandnitrogenisotopes,respectively.WiththeUSD(W)andCWinteractions,wecalculatethehalf-livesandneutronemissionprobabilitiesofneutron-richfluorineisotopeinthesdmodelspace,respectively.Thecalculatedhalf-livesandneutronemissionprobabilitiesrepro-ducerecentexperimentaldataverywell.Itseemstoshowthattheparticlesoftheneutron-richcarbonandnitrogenisotopesaremainlyexcitedinthespsdspace.Theβ-decayof21Ntotheneutronboundstatesin21Oismostlythefirstforbiddentransitionwhichmakestheneutronemissionprobabilityincrease.Thetheoreticalcalculationofβ-decayof25Fto25NewithCWinteractionshowsthatCWinteractionisbetterthanUSDinteraction.

  • 标签: 丰中子核 衰变 氮同位素 中子发射 模型空间 半衰期
  • 简介:Plasmasourceperformanceparameters,includingplasmaejectiondensityandvelocity,greatlyaffecttheoperationofashort-conduction-timeplasmaopeningswitch(POS).Inthispaper,theplasmasourceusedinthePOSofQiangguangIgeneratorischosenasthestudyobject.AtfirstthePOSworkingprocessisanalyzed.TheresultshowsthattheopeningperformanceofthePOScanbeimprovedbyincreasingtheplasmaejectionvelocityanddecreasingtheplasmadensity.Theinfluenceofthecableplasmagunstructureandnumberontheplasmaejectionparametersisexperimentallyinvestigatedwithtwochargecollectors.Finallyasemi-empiricalmodelisproposedtodescribetheexperimentalphenomenon.

  • 标签: 等离子体断路开关 等离子体源 性能参数 导通时间 等离子体密度 等离子体喷射
  • 简介:Opticalemissionspectroscopy(OES)wasappliedforplasmacharacterizationduringtheerosionofasphaltenesubstrates.Anamountof100mgofasphaltenewascarefullyappliedtoanelectrodeandexposedtoair-plasmaglowdischargeatapressureof1.0Torr.Theplasmawasgeneratedinastainlesssteeldischargechamberbyanacgeneratoratafrequencyof60Hz,outputpowerof50Wandagasflowrateof1.8L/min.Theelectrontemperatureandiondensitywereestimatedtobe2.15±0.11eVand(1.24±0.05)×1016m-3,respectively,usingadoubleLangmuirprobe.OESwasemployedtoobservetheemissionfromtheasphalteneexposedtoairplasma.BothmolecularbandemissionfromN2,N+2,OH,CH,NH,O2aswellasCN,andatomiclightemissionfromVandHγwereobservedandusedtomonitortheevolutionofasphalteneerosion.Theasphalteneerosionwasanalyzedwiththeaidofascanningelectronmicroscope(SEM)equippedwithanenergydispersiveX-ray(EDX)detector.TheEDXanalysisshowedthatthetimeevolutionofelementsC,O,SandVweresimilar;andthechemicalcompositionoftheexposedasphaltenesremainedconstant.Particlesizeevolutionwasmeasured,showingamaximumsizeof2307μmafter60min.Thisbehaviorismostlikelyrelatedtoparticleagglomerationasafunctionoftime.

  • 标签: 空气等离子 发射光谱仪 沥青基材 侵蚀过程 离子反应 表面分析
  • 简介:Ananalyticalstudyispresentedonthemodaldispersioncharacteristics,groupvelocity,andeffectivegroup,aswellasthephaseindexofaternaryonedimensionalplasmaphotoniccrystalforanobliquelyincidentelectromagneticwaveconsideringtheeffectofcollisionsinplasmalayers.Thedispersionrelationisderivedbyusingthetransfermatrixmethodandtheboundaryconditionsbasedonelectromagnetictheory.Thedispersioncurvesareplottedforboththenormalphotonicbandgapstructureandtheabsorptionphotonicbandgapstructure.Itisfoundthattheincreaseintheangleofincidenceshiftsthephotonicbandgaptowardhigherfrequencies.Also,thecutofffrequencyisindependentofcollisions.

  • 标签: 倾斜入射 等离子体 电磁波 碰撞 晶体性能 一维
  • 简介:Inthepaper,relativisticfilamentationofintenselaserbeamininhomogeneousplasmaisinvestigatedbasedonthenonparaxialregiontheory.Theresultsshowthat,relativisticnonlinearityplaysamainroleinbeamfilamentation,andplasmainhomogeneityfurtherreinforcesthebeamfilamentation.Thecombinationeffectsofrelativisticnonlinearityandplasmainhomogeneitycangenerateparticularlyintenseandshortpulselaser.However,plasmainhomogeneityleadstoobviousfilamentationinstability.

  • 标签: 非均匀等离子体 强激光束 相对论 成丝 不均匀性 短脉冲激光
  • 简介:AwaterplasmawasgeneratedbyDCarcdischargewithahafniumembeddedrodtypecathodeandanozzle-typeanode.Thedischargecharacteristicswereexaminedbychangingtheoperationparameterofthearccurrent.Thedynamicbehaviorofthearcdischargeledtosignificantfluctuationsinthearcvoltageanditsfrequency.Analysesofthehighspeedimageandthearcvoltagewaveformshowedthatthearcdischargewasintherestrikemodeanditsfrequencyvariedwithinseveraltensofkilohertzaccordingtotheoperatingconditions.Thelargerthermalplasmavolumewasgeneratedbythehigherflowfromtheformingsteamwithahigherrestrikefrequencyinthehigherarccurrentconditions.Inaddition,thecharacteristicsofthewaterplasmajetwereinvestigatedbymeansofopticalemissionspectroscopytoidentifytheabundantradicalsrequiredinanefficientwastetreatmentprocess.

  • 标签: 水等离子体 放电特性 直流电弧 应用 环境 电弧放电
  • 简介:Lowtemperatureairplasmawasusedasthemutationtoolforpenicillin-producingstrainPenicilliumchrysogenum.ThedischargeconditionswereRFpowerof360W,temperatureof40℃inasealedchamber,andpressureof10Pato30Pa.Theresultshowedthatthekineticsofthesurvivalratefollowedatypicalsaddle-shapedcurve.Basedonastatisticanalysis,atthetreatingdurationof10min,thepositivemutationratewasashighas37.5%whilethenegativemutationratewaslow.Thecolonialmorphologychangedobviouslywhentheplasmatreatingdurationreachedorexceeded45min.Afterbothprimaryandsecondaryscreening,amutantdesignatedasaPc051310withhighproductivityofpenicillinwasobtained,andastrongmutageniceffectonP.chrysogenumwasobservedintheprocess.Itwasprovedthatafterfivegenerations,themutantaPc051310stillexhibitsahighproductivity.Alltheresultsprovethattheplasmamutationmethodcouldbedevelopedasaconvenientandeffectivetooltobreedhigh-yieldstrainsinthefermentationindustry,whileexpandingtheplasmapplicationatthesametime.

  • 标签: 低温空气等离子体 产黄青霉 诱变效应 诱变育种 青霉素产生菌 宾夕法尼亚州
  • 简介:Basedonthefundamentalideasconcerningmicrowaveattenuationinplasma,weobtainanewexpressionoftransmissionattenuationofmicrowavesasafunctionoftheincidentwavefrequency.Andwithreasonablehypothesis,analyticalformsoftheelectrondensityandtheelectron-neutralcollisionfrequencyarederivedfromtheequationsofthetransmissionattenuationofmicrowavesattwonearfrequencies.Thismethodgivesaneffectiveandeasyapproachtodiagnosetheunmagnetizedplasma.

  • 标签: 非磁化等离子体 诊断理论 解析表达式 双频 碰撞频率 微波衰减
  • 简介:AmedicalcastCoCrMoalloywascoatedbyplasmanitridingprocesstoenhancethewearresistance.Themicrostructures,phasesandmicro-hardnessofnitridedlayerswereinvestigatedbyatomicforcemicroscopy(AFM),scanningelectronmicroscopy(SEM),X-raydiffraction(XRD)andmicro-hardness.Tribologicalpropertieswereinvestigatedonapin-on-discweartesterunder25%bovineserumsolutions.Theexperimentalresultsshowedthatplasmanitridingwasapromisingprocesstoproducethick,hardandwearresistantlayersonthesurfaceofCoCrMoalloy.TheharderCrNandCr2Nphasesformedontheplasmanitridedlayerwiththecompactnano-crystallinestructure.Comparedwiththeuntreatedsample,allnitridedsamplesshowedthelowerwearratesandhigherwearresistanceatdifferentappliedloadsandnitridingtemperatures.Itwasconcludedthattheimprovementofwearresistancecouldbeascribedtotheformationofthickerandhardernitridedlayerswiththespecificmicrostructuresonnitridedsurfaces.

  • 标签: 英文摘要 材料科学 优秀论文 科技学报
  • 简介:Theglidingarccanofferhighenergyefficiencyandselectivityforchemicalreactionsandhasbeenwidelyappliedinmaterialprocessing,environmentalprotectionandotherindustrialareas.Butthedischargeproperties,measurementofplasmaparametersandrelatedphysicalpro-cessesoftheglidingarcdischargestillneedtofurtherstudied.Inthisstudy,theglidingarcwasdrivenbythetransversemagneticfieldtoproducethenon-equilibriumplasmaathighpressure.Theparametersoftheplasmaatourobservedpointweremeasuredbyopticalmethods.Theexperimentalresultshowsthattheelectrontemperatureisabout0.6eVandtheheavyparticletemperatureisapproximately2987±250K.

  • 标签: 等离子体参数 滑动弧放电 横向磁场 测量 驱动 非平衡等离子体
  • 简介:Magnetohydrodynamic(MHD)acceleratorisproposedasanextgenerationpropulsionsystem.Itcanbeusedtoincreasetheperformanceofapropulsionsystem.TheobjectiveofthisstudyistoinvestigatetheperformanceofMHDacceleratorusingnon-equilibriumairplasmaasworkinggas.Inthisstudy,thefundamentalperformanceofMHDacceleratorsuchasflowperformanceandelectricalperformanceisevaluatedatdifferentlevelsofappliedmagneticfieldusing1-Dnumericalsimulation.ThenumericalsimulationisdevelopedbasedonasetofdifferentialequationswithMHDapproximation.TosolvethissetofdifferentialequationstheMacCormackschemeisused.AspecifiedchanneldesignedanddevelopedatNASAMarshallSpaceFlightCentreisusedinthenumericalsimulation.Thecompositionofthesimulatedairplasmaconsistsofsevenspecies,namely,N2,N,O2,O,NO,NO+,ande-.Theperformanceofthenon-equilibriumMHDacceleratorisalsocomparedwiththeequilibriumMHDaccelerator.

  • 标签: 空气等离子 MHD 加速器 非平衡 数值分析 MacCormack格式
  • 简介:Inourpreviouswork,aplasmaapproachforsingleattosecondpulse(AP)generationwasproposed.Afew-cyclerelativisticcircularlypolarizedlaserpulsewillinduceasingledrasticoscillationofplasmaboundary,fromwhichhigh-orderharmonicsandfurthermoreanultra-intensesingleAPcanbegeneratednaturallyafteritisreflected.Analyticalmodelandsimulationsbothdemonstratethattheprocessismostlyefficientasthepulsedurationisclosetotheplasmarespondingtime.Theeffectsofplasmadensityrampareanalyzedhere,suggestingthattheproposalisstillquiteefficientwithappropriatedensitygradientintheramp.Atlast,acombinedapproachisemployedtoobtainsingleAPwith30fsincidentlaser.Therelativelylarge-durationpulseisfirstlyshortenedbyadensitydroppingthinfoil,andthenreflectedfromanoverdenseplasmatarget.One-dimensionalsimulationshowsthata600assinglelightpulseisgeneratedwithpeakintensityof3×1020W/cm2.

  • 标签: 等离子体边界 阿秒脉冲 脉冲产生 超强 脉冲持续时间 等离子体密度
  • 简介:Waterisanimportantcomponentinplantcellswithplantaquaporinbeingthemajorproteinforwatertransportinandbetweenplantcells.Asasubfamilyofplantaquaporins,theplasmamembraneintrinsicproteins(PIPs)locatedintheplasmamembraneareclassic,highwater,selectivechannelproteins.ThispaperfocusesonrecentadvancesinthemolecularbiologyofPIPsconcerningstructuralcharacteristics,biologicalfunction,andaregulationmechanism.PIPspossesstwohighlyconserveddomains:GGGANXXXXGYandTGI/TNPARSL/FGAAI/VI/VFWF/YN.PIPscanalsobedividedintotwophylogeneticsubgroupsnamedPIP1andPIP2.PIP1possesseslongerNterminalsequencesandshorterCterminalsequencesthanPIP2withconservedaminoacidsequencesrespectively.StudiesoftransgenicplantsandexpressioninXenopusoocytescellsindicatethatPIPsnotonlymayfacilitatetransportofwaterandsmallneutralsoluteslikeCO2andglycerin,buttheyalsopossessmanyphysiologicalfunctions.Thefunctionsofplantaquaporinsareregulatedbymanyfactorsincludingpost-translationalmodification,heteromerization,pHvalue,anddivalentcations.TheseresultsindicatedthatPIPsactasapivotalroleinwaterandsmallneutralsolutestransportinplants.

  • 标签: BOTANY plasma membrane INTRINSIC proteins(PIPs) function
  • 简介:Intheplasmasheathanarrowplasmachannelgeneratedbyultraintenselaserpulsesissimplifiedasaspecialcylindricalandhollowplasmawaveguidewiththeinfinitethicknessoftheplasmacladding.Theelectromagneticwave(EM)propagationpropertiesoftheplasmachannelnearthecutoffandfarfromthecutoffareconsidered.TheoreticalanalysisshowsthatTE0mandTM0mandhybridmodesemergeintheplasmachannel,whichisinfluencedbythenormalizedfrequencyparameterBandnumericalapertureNA.Thecutoffsofthevariousmodesareapproximated.Single-modeoperationispossiblewithoutahigh-frequencylimitationinthechannel.

  • 标签: 等离子体通道 电磁波 传播理论 预制 超强激光脉冲 离子通道
  • 简介:电子温度和电子数字密度是在血浆的描述的重要参数。在电子温度和土壤血浆的电子数字密度由激光产生了的这份报纸,脱离在不同分泌物电压与毫微秒分泌物火花结合了被学习了。Saha-Boltzmann阴谋并且空拓宽被用来决定温度和电子数字密度。本地热平衡在毫微秒火花被完成,这被证明提高的血浆。提高的光排放,到噪音比率的信号和以在不同火花电压的信号紧张的相对标准差的稳定性详细被调查。一个相对稳定的分泌物过程在带的试验性的配置下面与10kV分泌物电压的使用被观察。

  • 标签: 土壤温度 电子密度 等离子体 Stark加宽 电子数密度 放电电压
  • 简介:导致激光的血浆今天代表普遍分光镜的排放来源。它能容易用紧缩、可靠的毫微秒被产生材料的一个大变化上的搏动的激光。它为例如有导致激光的故障光谱学(解放)的spectrochemical分析的申请变得那么流行一个人趋于忘记导致它的产生并且管理它的进化的复杂物理、化学的过程。这篇评论文章的目的是总结必要的背景从它的产生理解并且描述导致激光的血浆到它的扩大进周围的气体。目的是不详细说明每个过程的细节;在文学为那有众多的专业化论文和书。这里的目标是在必要理解元素需要从一个复杂过程把导致激光的血浆描述为结果的一份一样的报纸聚在一起。这些元素能在背景气体在象激光事相互作用,材料的激光脱离,热、电离的气体的光、热力学的性质,或血浆繁殖那样的几块相关却独立的地里被驱散。我们相信那介绍以一条全面的路并且在这份报纸的有限的页理解导致激光的血浆的元素的整体将对进一步的开发有用并且优化LIBS技术的使用。每次如此的说明变得可能、有用,在我们的实验室获得的试验性的结果被用来说明学习物理过程。

  • 标签: 激光诱导等离子体 等离子体光谱 发射源 纳秒脉冲激光 光谱化学分析 物理过程
  • 简介:教育改革的大环境促使教育界既要注重教法的研究与创新,又要积极探索和构建与之相适应的评价模式。作为一种新的英语教学模式,RICH教学法在教学组织上有自己独特的优势,但教学效果如何还需科学而完善的评测。以RICH教学法为载体,探讨如何把先进的语言评价理论与职业院校英语教学的具体实践结合起来,探讨RICH视角下的职业院校英语教学评价模式的实施步骤和可操作性,构建一套一种态度+两类考试+三项能力+一个目标的评价模式(即1231评价模式).推动职业院校英语教学评价模式的改革。

  • 标签: RICH教学模式 职业院校 英语教学评价模式 契合点
  • 简介:Azero-dimensionalmodelwhichincludes56speciesofreactantsand427reactionsisusedtostudythebehaviorofchargedparticlesinatmosphericplasmaswithdifferentionizationdegreesatlowaltitude(near0km).TheconstantcoefficientnonlinearequationsaresolvedbyusingtheQuasi-steady-stateapproximationmethod.Theelectronlifetimesareobtainedforafterglowplasmawithdifferentinitialvalues,andthetemporalevolutionsofthemainchargedspeciesarepresented,whicharedominantinreactionprocesses.Theresultsshowthattheelectronnumberdensitydecaysquickly.Thelifetimesofelectronsareshortenedbyabouttwoorderswithincreasingionizationdegree.Electronsthenattachtoneutralparticlesandproducenegativeions.Whentheinitialelectrondensitiesareintherangeof1010~1014cm3,thenegativeionshavesufficientlyhighdensitiesandlonglifetimesforairpurification,disinfectionandsterilization.Electrons,O2,O4,CO4andCO3arethedominantnegativespecieswhentheinitialelectrondensityne0≤1013cm3,andonlyelectronsandCO3areleftwhenne0≥1015cm3.N+2,N+4andO+2aredominantinthepositivechargesforanyionizationdegree.Otherpositivespecies,suchasO+4,N+3,NO+,NO+2,Ar+2andH3O+·H2O,aredominantonlyforacertainionizationdegreeandinacertainperiod.

  • 标签: 大气等离子体 低海拔地区 带电粒子 电离度 电子数密度 演变
  • 简介:Atypeofelectricaldischargecalledslidingdischargewasdevelopedtogenerateplasmaaerodynamicactuationforflowcontrol.Athree-electrodeplasmasheetactuatordrivenbyrepetitivenanosecondpulseswithanegativeDCcomponentwasusedtogenerateslidingdischarge,whichcanbecallednanosecond-pulseslidingdischarge.Thephenomenologyandbehaviouroftheplasmasheetactuatorwereinvestigatedexperimentally.Dischargemorphologyshowsthattheformationofnanosecond-pulseslidingdischargeisdependentonthepeakvalueoftherepetitivenanosecondpulsesandnegativeDCcomponentappliedontheplasmasheetactuator.Comparedtodielectricbarrierdischarge(DBD),theextensionofplasmainnanosecond-pulseslidingdischargeisquasi-diffusive,stable,longerandmoreintensive.TestresultsofparticleimagevelocimetrydemonstratethatthenegativeDCcomponentappliedtoathirdelectrodecouldsignificantlymodifythetopologyoftheflowinducedbynanosecond-pulseDBD.Bodyforceinducedbythenanosecond-pulseslidingdischargecanbeapproximatelyintheorderofmN.BoththemaximumvelocityandthebodyforceinducedbyslidingdischargeincreasesignificantlyascomparedtosingleDBD.Therefore,nanosecond-pulseslidingdischargeisapreferableplasmaaerodynamicactuationgenerationmode,whichisverypromisinginthefieldofaerodynamics.

  • 标签: 等离子体片 纳秒脉冲 直流分量 脉冲驱动 脉冲放电等离子体 执行机构