学科分类
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34 个结果
  • 简介:AfewCT-basedvoxelphantomswereproducedtoinvestigatethesensitivityofMonteCarlosimulationsofX-raybeamandelectronbeamtotheproportionsofelementsandthemassdensitiesofthematerialsusedtoexpressthepatient'sanatomicalstructure.Thehumanbodycanbewelloutlinedbyair,lung,adipose,muscle,softboneandhardbonetocalculatethedosedistributionwithMonteCarlomethod.TheeffectsofthecalibrationcurvesestablishedbyusingvariousCTscannersarenotclinicallysignificantbasedonourinvestigation.ThedeviationfromthevaluesofcumulativedosevolumehistogramderivedfromCT-basedvoxelphantomsislessthan1%forthegiventarget.

  • 标签: 蒙特卡洛法 核辐射 临界分布计算 标定曲线 计算机断层摄影
  • 简介:Asanimportantnon-ferrousmetalstructuralmaterialmostusedinindustryandproduction,aluminum(Al)alloyshowsitsgreatvalueinthenationaleconomyandindustrialmanufacturing.HowtoclassifyAlalloyrapidlyandaccuratelyisasignificant,popularandmeaningfultask.Classificationmethodsbasedonlaser-inducedbreakdownspectroscopy(LIBS)havebeenreportedinrecentyears.AlthoughLIBSisanadvanceddetectiontechnology,itisnecessarytocombineitwithsomealgorithmtoreachthegoalofrapidandaccurateclassification.Asanimportantmachinelearningmethod,therandomforest(RF)algorithmplaysagreatroleinpatternrecognitionandmaterialclassification.ThispaperintroducesarapidclassificationmethodofAlalloybasedonLIBSandtheRFalgorithm.TheresultsshowthatthebestaccuracythatcanbereachedusingthismethodtoclassifyAlalloysamplesis98.59%,theaverageofwhichis98.45%.ItalsorevealsthroughtherelationshiplawsthattheaccuracyvarieswiththenumberoftreesintheRFandthesizeofthetrainingsamplesetintheRF.Accordingtothelaws,researcherscanfindouttheoptimizedparametersintheRFalgorithminordertoachieve,asexpected,agoodresult.TheseresultsprovethatLIBSwiththeRFalgorithmcanexactlyclassifyAlalloyeffectively,preciselyandrapidlywithhighaccuracy,whichobviouslyhassignificantpracticalvalue.

  • 标签: LASER-INDUCED BREAKDOWN spectroscopy(LIBS) random forest(RF) aluminum(Al)alloy
  • 简介:Theaccuracyoflaser-inducedbreakdownspectroscopy(LIBS)quantitativemethodisgreatlydependentontheamountofcertifiedstandardsamplesusedfortraining.However,inpracticalapplications,onlylimitedstandardsampleswithlabeledcertifiedconcentrationsareavailable.Anovelsemi-supervisedLIBSquantitativeanalysismethodisproposed,basedonco-trainingregressionmodelwithselectionofeffectiveunlabeledsamples.Themainideaoftheproposedmethodistoobtainbetterregressionperformancebyaddingeffectiveunlabeledsamplesinsemi-supervisedlearning.First,effectiveunlabeledsamplesareselectedaccordingtothetestingsamplesbyEuclideanmetric.Twooriginalregressionmodelsbasedonleastsquaressupportvectormachinewithdifferentparametersaretrainedbythelabeledsamplesseparately,andthentheeffectiveunlabeledsamplespredictedbythetwomodelsareusedtoenlargethetrainingdatasetbasedonlabelingconfidenceestimation.Thefinalpredictionsoftheproposedmethodonthetestingsampleswillbedeterminedbyweightedcombinationsofthepredictionsoftwoupdatedregressionmodels.Chromiumconcentrationanalysisexperimentsof23certifiedstandardhigh-alloysteelsampleswerecarriedout,inwhich5sampleswithlabeledconcentrationsand11unlabeledsampleswereusedtotraintheregressionmodelsandtheremaining7sampleswereusedfortesting.Withthenumbersofeffectiveunlabeledsamplesincreasing,therootmeansquareerroroftheproposedmethodwentdownfrom1.80%to0.84%andtherelativepredictionerrorwasreducedfrom9.15%to4.04%.

  • 标签: LIBS EFFECTIVE unlabeled samples CO-TRAINING SEMI-SUPERVISED
  • 简介:ApoolcooledexperimentalmagnetbasedonthecopperstabilizedNbTisuperconductingwirewasdesigned,fabricatedandtested,inordertoevaluatetheengineeringdesignofthedipolesuperconductingmagnetforthecollectorring(CR)ofthefacilityforantiprotonandionresearch(FAIR)project.Inthispaper,theexperimentalsetupincludingquenchprotectionsystemwaspresented.Performanceoftheliquidheliumpoolcooledtestwasintroduced.Alloftheresultsindicateboththeperformanceofconductorandtheexperimentalsuperconductingmagnetunderlowtemperatureisstable,whichsuggeststheengineeringdesignarefeasiblefortheformalmagnetinCRoftheFAIRproject.

  • 标签: 实验装置 超导磁体 集电环 工程设计 性能测试 NBTI
  • 简介:Thetriple-to-doublecoincidenceratio(TDCR)methodofliquidscintillationcount-ingisanabsolutemeasurementmethodofradioactivity.TheformulationoftheTDCRmethodandtheestablishedTDCRliquidscintillationcounterarepresentedinthispaper.TheNISTstandardreferencematerial(SRM)oftritiumwaterwasmeasuredtoverifytheperformanceoftheTDCRliquidscintillationcounter.

  • 标签: 氚水 液体闪烁计数器 标准化 标准参考物质 测量方法 NIST
  • 简介:An8-channelHCNlaserinterferometerwillbeinstalledonHL-2Ainnearterm.InordertogetthespatialprofileoftheelectrondensityBarrnumericalmethodisadoptedtorealizetheAbelinversion.InthisarticletheresultoftheAbelinversionbyMatlabGUIisgivenwhichcanbeupdatedtoprocessthemeasureddataofthe8-channellaserinterferometerandprovidethespatialdistributionoftheelectrondensity.

  • 标签: 等离子体物理 托卡马克装置 数值计算 亚伯倒置 MATLAB
  • 简介:Inapoloidalfield(PF)convertermodule,fuseprotectionisofgreatimportancetoensurethesafetyofthethyristors.Thefuseispre-selectedinatraditionalwayandthenverifiedbyfiniteelementanalysis.A3DphysicalmodelisbuiltbyANSYSsoftwaretosolvethethermalelectriccoupledproblemoftransientprocessincaseofexternalfault.Theresultshowsthatthismethodisfeasible.

  • 标签: 保护设计 保险丝 有限元法 ANSYS软件 应用 有限元分析
  • 简介:Implementationofaweb-basedlogbooksystemonEASTisintroduced,whichcanstorethecommentsfortheexperimentsintoadatabaseandaccessthedocumentsviavariouswebbrowsers.Thethree-tiersoftwarearchitectureandasynchronousaccesstechnologyareadoptedtoimprovethesystemeffectively.Authorizeduserscanviewtheinformationofreal-timedischarge,commentsfromothersandsignalplots;add,delete,orrevisetheirowncomments;searchsignaldataorcommentsundercomplicatedsearchconditions;andcollectrelevantinformationandoutputittoanexcelfile.Thewebpagescanbeautomaticallyupdatedafteranewdischargeiscompletedandwithoutrefreshment.

  • 标签: WEB浏览器 日志系统 实验 EXCEL文件 华东 接入技术
  • 简介:Theneutronfluxmonitor(NFM),asasignificantdiagnosticsystemintheInternationalThermonuclearExperimentalReactor(ITER),willplayanimportantroleinthereadingsofaseriesofkeyparametersinthefusionreactionprocess.AsthecoreofthemainelectronicsystemoftheNFM,theneutron-gammapulseshapediscrimination(n-γPSD)candistinguishtheneutronpulsefromthegammapulseandotherdisturbingpulsesaccordingtothethresholdsoftherisingtimeandtheamplitudepre-installedontheboard,thedoubletimingpointCFDmethodisusedtogettherisingtimeofthepulse.Then-γPSDcanprovideanaccurateneutroncount.

  • 标签: 脉冲形状 中子通量 判别方法 国际热核实验堆 国际热核实验反应堆 检测
  • 简介:Athreedimensionalbounce-averagedFokker-Planck(FP)numericalcodehasbeennewlydevelopedbasedonfullyimplicititerativesolvingmethod,andrelativisticeffectisalsoincludedinthecode.Thecodehasbeentestedagainstvariousbenchmarkcases:OhmicconductivityinthepresenceofweakOhmicelectricfield,runawaylossesofelectronsinthepresenceofstrongOhmicelectricfield,lowerhybridcurrentdriveandelectroncyclotroncurrentdriveviatwo-orthree-dimensionalsimulation.Allthetestcasesrunfastandcorrectlyduringcalculations.Asaresult,thecodeprovidesasetofpowerfultoolsforstudyingradiofrequencywaveheatingandcurrentdriveintokamakplasmas.

  • 标签: FOKKER-PLANCK方程 托卡马克等离子体 求解方法 电子回旋电流驱动 迭代 低杂波电流驱动
  • 简介:Non-contactmagneticmeasurementmethodisaneffectivewaytostudytheairarcbehaviorexperimentally.Oneofthecrucialtechniquesistosolveaninverseproblemfortheelectromagneticfield.Thisstudyisdevotedtoinvestigatingdifferentalgorithmsforthiskindofinverseproblempreliminarily,includingthepreconditionedconjugategradientmethod,penaltyfunctionmethodandgeneticalgorithm.Thefeasibilityofeachalgorithmisanalyzed.Itisshownthatthepreconditionedconjugategradientmethodisvalidonlyforfewarcsegments,theestimationaccuracyofthepenaltyfunctionmethodisdependentontheinitialconditions,andtheconvergenceofgeneticalgorithmshouldbestudiedfurtherformoresegmentsinanarccurrent.

  • 标签: 电磁场逆问题 应用算法 测量方法 反问题 预处理共轭梯度法 预条件共轭梯度法
  • 简介:Neutrondiagnostics,includingfluxandenergyspectrummeasurements,havebeenappliedontheexperimentaladvancedsuperconductingtokamak(EAST).TheabsolutecalibrationofneutronyieldshasbeenachievedbyacalculationmethodusingtheMonteCarloautomaticmodeling(MCAM)systemandtheMonteCarloN-Particles(MCNP)code.Sincetheneutronyieldiscloselyrelatedwiththeiondensityandtemperature,itisagoodmeasureofplasmaperformance,especiallythewaveheatingeffect.Inioncyclotronrangeoffrequencies(ICRF)experiments,theincreaseintheiontemperaturederivedbytheneutronyieldindicatesaneffectiveplasmaheating.Minorityprotonsdampalargefractionofthetotalwavepower,andthentransferpartoftheenergytodeuteriumbycollisions.NeutronspectrummeasurementsalsoindicatethatnotailiscreatedbyhighenergydeuteronsduringICRFheating.However,theiontemperaturederivedbytheneutronyieldisconsistentwiththeresultbyusingapoloidalX-rayimagingcrystalspectrometer(PXCS),showingareliabletransportcalculation.

  • 标签: 等离子体性能 中子产额 ICRF 计算 中子能谱测量 暖气
  • 简介:Atriggerdeviceandatriggeredpseudosparkswitch(TPSS)weredesignedbasedonsurfaceflashovertechnology,inordertomeettherequirementsfrompresentpulsepowertechnol-ogyandpulsecurrenttesttechnologysuchasalonglifetime,reliabilityinawidevoltagerange,ashortdelaytime,aswellassmalldelayjitters.Thetriggerdevicesweremadefromdifferentdielectricmaterials,withtheirpermittivitiesfromtenstothousands.ThetriggercharacteristicsofTPSSwereinvestigated.Theresultsindicatethatthehigh-dielectrictriggerdeviceshowsbetterperformanceandhigheremittedchargeoftheelectronemissionwithinalladjustedparametersincludingthegaspressureandappliedvoltage.Forthedielectricmaterialwithrelativepermittiv-ityε_rof3460,whenthegaspressureis7Pa,thehold-offvoltageofTPSSis28kV,theminimumtriggerswitchvoltagedropsto128V,theminimumdischargingdelaytimeanddelayjitterarelessthan35nsand6ns,respectively,andthereliableoperationcanbereachedwithinaverylargerangeofchargingvoltage,between0.46%and99%ofitsself-breakdownvoltage.

  • 标签: 触发器特性 伪火花开关 沿面闪落特性 实验研究
  • 简介:Breakdowncharacteristicsofagapbreakdownloadwasinvestigatedinthispaper,andareverselyswitcheddynistor(RSD)dischargecircuitwasdesignedbasedontheload.Basedonthecharacteristicsoftheload,theRSDdischargecircuitwasimprovedandoptimized.Thevolumeofthemagneticswitchwasreduced.ToprotectthethyristorandRSD,adiodewasantiparallelyconnectedwiththethyristor,whichreducedthetimerequirementwhenapowervoltagewasappliedtoRSD.Experimentalresultsshowthecircuitdesignedinthispapercanswitchahighvoltageandhighcurrentsmoothly,andallowsthepowervoltagetochangeinawiderrange.

  • 标签: 击穿特性 放电间隙 反向 实验 负荷 放电电路
  • 简介:Amulti-objectivehybridgeneticbasedoptimizationalgorithmisproposedaccordingtothemulti-objectivePropertyofinverseplanning.Itisbasedonhybridadaptivegeneticalgorithmwhichcombinesthesimulatedannealing,usesadaptivecrossoverandmutation,andadoptsnichedtournamentselection.Theresultoftheteatcalculatationdemonstratesthatanexcellentconvergingspeedcanbeachievedusingthisapproach.

  • 标签: 反转计划 多目标优化 遗传算法 等离子物理
  • 简介:Ageneratoroftheglidingarcjet(GAJ),whichisdrivenbyatransversemagneticfield,isdevelopedtoproducenon-equilibriumplasmaatatmosphericpressure.ThegastemperatureisestimatedusingthespectrumofOHradicalstobeabout2400±400K.Thedeterminationsofelectrontemperatureandelectrondensitybyusingaline-ratiomethodareelaboratedfortheglidingarcjetplasma.Thisline-ratiomethodisbasedonacollisional-radiativemodel.Theexperimentresultsshowthatelectrontemperatureisabout1.0eVandelectrondensityisabout6.9×1014cm-3.Obviously,theplasmaofGAJisinanon-equilibriumstate.

  • 标签: 等离子体参数 大气压力 滑动弧 非平衡等离子体 线路 流通