学科分类
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38 个结果
  • 简介:与作为分别地散布和镜子的部件使模型和零平均数的随机的窦状隙褪色的改进瑞利一起,一个随机的模拟模型为使波形褪色的瑞利和Rician的产生被建议。与存在相比随机的模型,建议模拟器需要仅仅一试用就算样品的数字不足够大,获得需要的统计性质。而且,建议模拟模型能直接为不同褪色的情形产生多重uncorrelated波形,例如单个输入的单个产量的频率选择隧道和多重输入的多重产量的隧道。建议模拟器有效、精确的表演评估和比较表演。

  • 标签: 莱斯衰落 模拟器 瑞利 频率选择性衰落信道 随机模拟模型 输出通道
  • 简介:ComputingtheeigenvalueofsmallestmodulusanditscorrespondingeigneveclorofanirreduciblenonsingularM-matrixAisconsidered,ItisshownthatiftheentriesofAareknownwithhighrelativeaccuracy,itseigenvalueofsmallestmodulusandeachcomponentofthecorrespondingeigenvectorwillbedeterminedtomuchhigheraccuracythanthestandardperturbationtheorysuggests.Analgorithmispresentedtocomputethemwithasmallcomponentwisebackwarderror,whichisconsistentwiththeperturbationresults.

  • 标签: IRREDUCIBLE NONSINGULAR M-MATRIX BACKWARD ERROR componentwise
  • 简介:Weexperimentallydemonstrateextractionofsiliconwaveguidegeometrywithsubnanometeraccuracyusingopticalmeasurements.Effectiveandgroupindicesofsilicon-on-insulator(SOI)waveguidesareextractedfromtheopticalmeasurements.AnaccuratemodellinkingthegeometryofanSOIwaveguidetoitseffectiveandgroupindicesisusedtoextractthelinewidthsandthicknesseswithinrespectiveerrorsof0.37and0.26nmonadiefabricatedbyIMECmultiprojectwaferservices.Adetailedanalysisofthesettingoftheboundsfortheeffectiveandgroupindicesispresentedtogettherightextractionwithimprovedaccuracy.

  • 标签: MZI ACCURATE EXTRACTION MEASUREMENT
  • 简介:Anefficientandaccuratemethodforsolvingthetwo-dimensionalHelmholtzequationindomainsexteriortoelongatedobstaclesisdevelopedinthispaper.Themethodisbasedonthesocalledtransformedfieldexpansion(TFE)coupledwithaspectral-GalerkinsolverforellipticaldomainusingMathieufunctions.Numericalresultsarepresentedtoshowtheaccuracyandstabilityoftheproposedmethod.

  • 标签: 椭圆函数 声散射 光谱法 有效率 亥姆霍兹方程 聚四氟乙烯
  • 简介:Weperformanalysisforafiniteelementsmethodappliedtothesingularself-adjointproblem.Thismethodusescontinuouspiecewisepolynomialspacesforthetrialandthetestspaces.WefitthetrialpolynomialspacebypiecewiseexponentialsandweapplysoexponentiallyfittedGalerkinmethodtosingularself-adjomtproblembyapproximatingdrivingtermsbyLagrangepiecewisepolynomials,linear,quadraticandcubic.Wtmeasuretheerroeinmaxnorm.Weshowthatmethodisoptimalofthefirstorderintheerrorestimate,WealsogivenumericalresultsfortheGalerkinapproximation.

  • 标签:
  • 简介:Forthestabilityrequirementofnumericalresultants,themathematicaltheoryofclassicalmixedmethodsarerelativelycomplex.However,generalizedmixedmethodsareautomaticallystable,andtheirbuildingprocessissimpleandstraightforward.Inthispaper,basedontheseminalideaofthegeneralizedmixedmethods,asimple,stable,andhighlyaccurate8-nodenoncompatiblesymplecticelement(NCSE8)wasdevelopedbythecombinationofthemodifiedHellinger-Reissnermixedvariationalprincipleandtheminimumenergyprinciple.Toensuretheaccuracyofin-planestressresults,asimultaneousequationapproachwasalsosuggested.NumericalexperimentationshowsthattheaccuracyofstressresultsofNCSE8arenearlythesameasthatofdisplacementmethods,andtheyareingoodagreementwiththeexactsolutionswhenthemeshisrelativelyfine.NCSE8hasadvantagesoftheclearingconcept,easycalculationbyafiniteelementcomputerprogram,higheraccuracyandwideapplicabilityforvariouslinearelasticitycompressibleandnearlyincompressiblematerialproblems.ItispossiblethatNCSE8becomesevenmoreadvantageousforthefractureproblemsduetoitsbetteraccuracyofstresses.

  • 标签: Modified H-R MIXED variational principle Partial-mixed
  • 简介:WiththedevelopmentofCMOSandMEMStechnologies,theimplementationofalargenumberofwirelessdistributedmicro-sensorsthatcanbeeasilyandrapidlydeployedtoformhighlyredundant,self-configuring,andadhocsensornetworks.Tofacilitateeaseofdeployment,thesesensorsoperateonbatteryforextendedperiodsoftime.Aparticularchallengeinmaintainingextendedbatterylifetimeliesinachievingcommunicationswithlowpower.Forbetterunderstandingofthedesigntradeoffsofwirelesssensornetwork(WSN),amoreaccurateenergymodelforwirelesssensornodeisproposed,andanoptimaldesignmethodofenergyeffcientwirelesssensornodeisdescribedaswell.DifferentfrompowermodelsevershownwhichassumethepowercostofeachcomponentinWSNnodeisconstant,thenewonetakesintoaccounttheenergydissipationofcircuitsinpracticalphysicallayer.Itshowsthattherearesomeparameters,suchasdatarate,carrierfrequency,bandwidth,Tsw,etc,whichhaveasignificanteffectontheWSNnodeenergyconsumptionperusefulbit(EPUB).Foragivenqualityspecification,howenergyconsumptioncanbereducedbyadjustingoneormoreoftheseparametersisshown.

  • 标签: WSNS 能量模式 最优设计 通信技术
  • 简介:HippocampalvolumelossisanimportantbiomarkerindistinguishingsubjectswithAlzheimer’sdisease(AD)anditsmeasurementinmagneticresonanceimages(MRI)isinfluencedbypartialvolumeeffects(PVE).Thispaperdescribesapost-processingapproachtoquantifyPVEforcorrectionofthehippocampalvolumebyusingaspatialfuzzyC-means(SFCM)method.Thealgorithmisevaluatedonadatasetof20T1-weightedMRIscanssampledattwodifferentresolutions.Thecorrectedvolumesforleftandrighthippocampus(HC)whichare23%and18%forthelowresolutionand6%and5%forthehighresolutiondatasets,respectivelyarelowerthanhippocampalvolumeresultsfrommanualsegmentation.ResultsshowtheimportanceofapplyingthistechniqueinADdetectionwithlowresolutiondatasets.

  • 标签: 体积损失 容积效应 准确测量 海马 阿尔茨海默氏病 高分辨率
  • 简介:Crustalstructureandaccuratehypocenterde┐terminationalongtheLongmenshanfaultzoneZHUZHAO1)(赵珠)JUNFAN1)(范军)SI-HUAZHENG2)(郑斯华)AK...

  • 标签: LONGMENSHAN fault zone P WAVE S
  • 简介:Distinguishingwithtraditionaltoothprofileofspiralbevelandhypoidgear,itproposedanewtoothprofilenamelythesphericalinvolute.Firstly,anewtheoryofformingthesphericalinvolutetoothprofilewasproposed.Then,thistheorywasappliedtocompleteparametricderivationofeachpartofitstoothprofile.Forenhancingtheprecision,theSWEEPmethodusedforformationofeachpartoftoothsurfaceandG1stitchingschemaforobtainingaunifiedtoothsurfaceareputforwardandmadetheapplicationintheaccuratemodeling.Lastly,owingtothehigheraccuracyoftoothsurfaceofoutputtedmodel,itgavesomeoptimizationapproaches.Givennumericalexampleaboutthemodelcanshowthatthisdesignedgearwithsphericalinvolutetoothprofilecanachievefastandaccurateparametricmodelingandprovideafoundationfortoothcontactanalysis(TCA)indigitizeddesignandmanufacture.更多还原

  • 标签: 螺旋锥齿轮 渐开线齿形 精确建模 齿面接触分析 渐开线齿廓 数字化设计
  • 简介:ACCURATE PIPE TOP-ENTRY JUNCTION MODEL FOR STEADY AND UNSTEADY FLOWSACCURATEPIPETOP-ENTRYJUNCTIONMODELFORSTEADYANDUNSTEADYFLO...

  • 标签: numerical simulation PIPE networks top-entry JUNCTION
  • 简介:介绍基于ENN计划构造了一个高精确的差别计划的研究。ENN计划和几高顺序精确性的概述中央计划;数字方法使用了;在加权的功能和计划的精确性之间的关系。

  • 标签: ENN SCHEME WENO SCHEME Shock-boundary-layer interaction.
  • 简介:ICSED(ImprovedClusterShadeEdgeDetection)algorithmandothervariousmethodstoaccuratelyandefficientlydetectedgesonsatellitedataarepresented.ErrorratecriterionisusedtostatisticallyevaluatetheperformancesofthesemethodsindetectingoceanicfeaturesforbothnoisefreeandnoisecontaminatedAVHRR(AdvancedVeryHighResolutionRadiometer)IRimagewithKuroshio.Also,practicalexperimentsindetectingtheeddyofKuroshiowiththesemethodsarecarriedoutforcomparison.ResultsshowthattheICSEDalgorithmhasmoreadvantagesthanothermethodsindetectingmesoscalefeaturesofocean.Finally,theeffectivenessofwindowsizeofICSEDmethodtooceanicfeaturesdetectionisquantitativelydiscussed.

  • 标签: detecting AVHRR Roberts OCEANIC PIXEL DETAILS
  • 简介:Inthiswork,afastandaccuratestationaryalignmentmethodforstrapdowninertialnavigationsystem(SINS)isproposed.IthasbeendemonstratedthatthestationaryalignmentofSINScanbeimprovedbyemployingthemultipositiontechnique,butthealignmenttimeoftheazimutherrorisrelativelylonger.Overhere,thetwo-positionalignmentprincipleispresented.OnthebasisofthisSINSerrormodel,afastestimationalgorithmoftheazimutherrorfortheinitialalignmentofSINSonstationarybaseisderivedfullyfromthehorizontalvelocityoutputsandtheoutputrates,andthenovelazimutherrorestimationalgorithmisusedforthetwo-positionalignment.Consequently,thespeedandaccuracyoftheSINS'sinitialalignmentisenhancedgreatly.Thecomputersimulationresultsillustratetheefficiencyofthisalignmentmethod.

  • 标签: 惯性导航系统 初始调节 KALMAN滤波器 可观察性 定位基
  • 简介:ThispaperderivestheLindellformulabasedonthegeneralizedvariationalprinciple.ForthecomplexdielectricconstantmeasurementofasmalllossydielectricrodwithRayleigh-Ritzmethod,anaccuratevariationalanalysisisgiven.Theconceptofcomplexfrequencyisintroducedingeneral,andthestabilityofthesolutionisdiscussed.Comparingwiththeresultofperturbationmethod,itisconcludedthatthedeviationofperturbationalgorithmshouldbetakenintoconsideration.

  • 标签: General VARIATIONAL principle Lindell FORMULATION Complex
  • 简介:在这份报纸,结果在导致激光的故障光谱学(解放)的第一应用上被介绍为在alpha石蜡的Mg集中的量的决心的技术。这种技术在与传统的方法的那些可比较的Mg集中给精确性,这被表明,作为ICP-OES,在短时间并且没有对样品准备的需要。为500ppb的顺序的Mg的察觉的限制被表明。而且,关于合适的刻度曲线和察觉(LOD)的限制的定义的实现的简短讨论被报导。CLC数字TP274

  • 标签: α-石蜡 镁含量 精确测量 激光诱导击穿光谱
  • 简介:Anewapproachisproposedtoaccuratelydeterminethethicknessoffilms,especiallyforultra-thinfilms,throughspectrum-fittingwiththeassistanceofaninterferencelayer.Thedeterminationlimitcanreachevenlessthan1nm.Itsaccuracyisfarbetterthanthatofthetraditionalmethods.Thisdeterminationmethodisverifiedbyexperiments,andthedeterminationlimitisatleast3.5nmcomparedwiththeresultsofatomicforcemicroscope(AFM).Furthermore,adoubleinterference-aidedspectrafittingmethodisproposedtoreducetherequirementsofthedeterminationinstruments,whichthusallowsonetodeterminethefilm’sthicknesswithalow-precisioncommonspectrometerandtogreatlylowerthecost.Itisaveryhigh-precisiondeterminationmethodforon-siteandin-situapplications,especiallyforultra-thinfilms.

  • 标签: 测定仪器 拟合方法 光谱仪 原子力显微镜 超薄薄膜 干涉