PMF软件参数

美国环保局认可的EPAPMF3.0模型软件Signaltonoiseratios(S/N=meanconcentration/meanuncertainty)信噪比S/N=平均浓度/平均不确定度（方法不唯一）Coefficientsofvariation(CV=standarddeviation/meanconcentration)变量系数CV=标准差/平均浓度（标准差=n2ii11(XX)n）《3.0使用向导》P15ItisadvisedthatFPEAKvaluesrangebetween−1and1,withpositivevaluescausingextremesintheFmatrix(valuesnear0or1)andnegativevaluescausingextremesintheGmatrix.Inthepresentwork,FPEAKiszeroforallPMF2solutions,whichcorrespondstothedefaultsetting.Theconcentrationvalueswereusedforthemeasureddata,andthesummationoftheanalyticaluncertaintyandonethirdofthedetectionlimitvaluewereusedastheoveralluncertaintyassignedtoeachmeasuredvalue.Themissingdatawerereplacedbythegeometricmeanofcorrespondingspecies,andfourtimesofgeometricmeanweretakenasthecorrespondinguncertainties.Valuesbelowthedetectionlimitwerereplacedbyhalfofthedetectionlimitvalues,andtheiroveralluncertaintiesweresetatfivesixthofthedetectionlimitvalues.Theuncertaintyofthevariableswascalculatedbasedonthedetectionlimitsandtheconcentrationofeachelectrometer:5/6ofthedetectionlimit(DL)wasusedascorrespondinguncertaintyfordatabelowthedetectionlimit(BDL).TheuncertaintiesfordataabovetheDLwerecalculatedaccordingtotheequationσij=DL/3+c×xij,whereσij=uncertainty,DL=detectionlimit,c=constant(0.1ifxij3DL,0.2ifxij≤3DL),andxij=concentrationoftheithvariableonthejthcase.Forstretchesalongwhichparticleconcentrationsequaledtozeroforacertainsizerange,thedatawerereplacedbyDL/2forthatsize.FPEAKvaluesbetween0.2and−0.2weretestedtoassesstheinfluenceofrotationsonthesolution,andthefinalvaluewassettoFPEAK=0.