简介：Thisstudytestedfivemethodswidelyusedinestimatingthecompletemagnitudes(MC)ofearthquakecatalogs.Usingcatalogsofobservedearthquakeproperties,wetesttheperformanceofthesefivealgorithmsunderseveralchallengingconditions,suchassmallvolumeofeventsandspatial-temporalheterogeneity,inordertoseewhetherthealgorithmsarestableandinagreementwithknowndata.Wefindthatthemaximumcurvaturemethod(MAXC)hasperfectstability,butwillsignificantlyunderestimateMCunlessheterogeneityisabsent.MCestimatedbytheb-valuestabilitymethod(MBS)requiresmanyeventstoreachastableresult.Resultsfromthegoodnessoffitmethod(GFT)wereunstablewhenheterogeneityloweredthefitnesslevel.Theentiremagnituderangemethod(EMR)isrelativelystableinmostconditions,andcanreflectthechangeinMCwhenheterogeneityexists,butwhentheincompletepartoftheearthquakecatalogisdismissed,thismethodfails.Themedian-basedanalysisofthesegmentslopemethod(MBASS)cantoleratesmallsamplesize,butisincapableofreflectingthemissingdegreeofsmalleventsinaftershocksequences.InconditionswhereMCchangesrapidly,suchasinaftershocksequences,observingthetimesequencedirectlycangiveapreciseestimationofthecompletesub-catalog,butonlywhenthenumberofeventsavailableforstudyislargeenoughcantheMAXC,GFT,andMBSmethodsgiveasimilarlyreliableestimation.

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简介：Weanalyzed360permanentandcampaignGPSdatafrom1999to2017inthesouthernSichuan-Yunanblock,andobtainedcrustalhorizontaldeformationinthisregion.Then,wederivedthestrainrateusingamulti-scalesphericalwaveletmethod.ResultsrevealacomplexpatternoftectonicmovementinthesouthernSichuan-Yunnanblock.ComparedtothestableEurasianplate,themaximumrateofthehorizontaldeformationinthesouthernSichuan-Yunnanblockisapproximately22mm/a.TheXiaojiangfaultshowsasignificantlylowerdeformation—aleft-lateralstrike-slipmovementof9.5mm/a.TheHonghefaultclearlyshowsacomplexsegmentaldeformationfromthenorthtosouth.ThenorthernHonghefaultshows4.3mm/arightstrike-slipwith6.7mm/aextension;thesouthernHonghefaultshows1.9mm/arightstrike-slipwith1.9mm/aextension;thejunctionzoneintheHongheandLijiang–Xiaojinhefaultsshowsanobviousclockwise-rotationdeformation.Thestraincalculationresultsrevealthatthemaximumshear-strainrateinthisregionreaches70nstrain/a,concentratedaroundtheXiaojiangfaultandatthejunctionoftheHongheandLijiang–Xiaojinhefaults.Wenotethatmostoftheearthquakeswithmagnitudesof4andabovethatoccurredinthisregionwerewithinthehighshearstrain-ratezonesandthestrainrategradientboundaryzone,whichindicatesthatthemagnitudeofstrainaccumulationiscloselyrelatedtotheseismicactivities.Comparisonofthefastshear-wavepolarizationdirectionoftheupper-crustwiththeupper-mantleanisotropyandthedirectionofthesurfaceprincipalcompressivestrainrateobtainedfromtheinversionoftheGPSdatarevealsthatthedirectionofthesurfaceprincipalcompressivestrainisbasicallyconsistentwiththefastshear-wavepolarizationdirectionoftheuppercrustanisotropy,butdifferentfromthepolarizationdirectionoftheuppermantle.OurresultssupportthehypothesisthattheprincipalelementsofthedeformationmechanisminthesouthernSichuan-Yunnanblockaredeco

简介：Amapoftheaverageatomicnumberoflunarrockandsoilcanbeusedtodifferentiatelithologyandsoiltypeonthelunarsurface.Thispaperestablishesalinearrelationshipbetweentheaverageatomicnumberoflunarrockorsoilandthefluxofpositionannihilationradiation(0.512-MeVgamma-ray)fromthelunarsurface.TherelationshipisconfirmedbyMonteCarlosimulationwithdatafromlunarrockorsoilsamplescollectedbyLuna(Russia)andApollo(USA)missions.AmapoftheaverageatomicnumberofthelunarrockandsoilonthelunarsurfacehasbeenderivedfromtheGamma-RaySpectrometerdatacollectedbyChang’e-1,anunmannedChineselunar-orbitingspacecraft.Inthemap,thehigheraverageatomicnumbers(ZA>12.5),whicharerelatedtodifferenttypesofbasalt,areinthemariaregion;thehighestZA(13.2)readingsareassociatedwithSinusAestuum.ThemiddleZA(~12.1)regions,intheshapeofirregularovalrings,areinWestOceanusProcellarumandMareFrigoris,whichseemstobeconsistentwiththedistributionofpotassium,rareearthelements,andphosphorusasauniquefeatureonthelunarsurface.Theloweraverageatomicnumbers(ZA<11.5)arefoundtobecorrelatedwiththeanorthositeonthefarsideoftheMoon.

简介：Twoassumptionsaretypicallymadewhenradarechosignalsfromprecipitationareanalyzedtodeterminethemicro-physicalparametersofraindrops:(1)theraindropsareassumedtobespherical;(2)multiplescatteringeffectsareignored.Radarcrosssections(RCS)areusuallycalculatedusingRayleigh'sscatteringequationwiththesimpleadditionmethodintheradarmeteorologicalequation.Weinvestigatetheextenttowhichconsiderationoftheeffectsofmultiplescatteringandofthenon-sphericalshapeswithinactualraindropswarmswouldresultinRCSvaluessignificantlydifferentfromthoseobtainedbyconventionalanalyticalmethods.First,weestablishsphericalandnon-sphericalraindropmodels,withGamma,JD,JT,andMPsizedistributions,respectively.WethenuseXFDTDsoftwaretocalculatetheradarcrosssectionsoftheaboveraindropmodelsattheS,C,XandKuradarbands.OurXFDTDresultsarethencomparedtoRCSvaluescalculatedbytheRayleighapproximationwithsimpleadditionmethods.Wefindthat:(1)RCSvaluescalculatedusingmultiplescatteringXFDTDsoftwarediffersignificantlyfromthosecalculatedbythesimpleadditionmethodatthesamebandforthesamemodel.Inparticular,forthesphericalraindropmodels,therelativedifferencesinRCSvaluesbetweenthemethodsrangefromamaximumof89.649%toaminimumof43.701%;forthenon-sphericalraindropmodels,therelativedifferencesrangefromamaximumof85.868%toaminimumof11.875%.(2)OurmultiplescatteringXFDTDresults,comparedtothoseobtainedfromtheRayleighformula,againdifferatallfoursizedistributions,byrelativeerrorsof169.522%,37.176%,216.455%,and63.428%,respectively.Whennonsphericaleffectsareconsidered,differencesinRCSvaluesbetweenourXFDTDcalculationsandRayleighcalculationsaresmaller;attheabovefoursizedistributionstherelativeerrorsare0.213%,0.171%,7.683%,and44.514%,respectively.RCSvaluescomputedbyconsideringmultiplescatteringandnon-sphericalparticleshapesarelargerthanRayleighRCS

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