简介：Inthispaper,theauthorsobtainacharacteristicthatacompleteRiemannianmanifoldturnsintoahyperbolicspaceform.

简介：<正>AssociatedwitheachfinitedirectedquiverQisaquasi-hereditaryalgebra.theso-calledtwisteddoubleofthepathalgebrakQ.Characteristictiltingmodulesoverthisclassofquasi-hereditaryalgebrasareconstructed.Theirendonorphismalgebrasareexplicitlydescribed.Itturnsoutthatthisclassofquasi-hereditaryalgebrasisclosedundertakingtheRingeldual.

简介：<正>Propertiesofcontinuoussolutionsofasecondorderpolynomial-likeiteratedfunctionalequationaregivenbyconsideringitscharacteristic.Ausefulmethodtodiscussthegeneralcaseisdescribedindeedinthisprocedure.

简介：ThispaperproposestheRiceconditionnumbersforinvariantsubspace,singularsubspacesofamatrixanddeflatingsubspacesofaregularmatrixpair.Thefirst-orderperturbationestimationsforthesesubspacesarederivedbyapplyingperturbationexpansionsoforthogonalprojectionoperators.

简介：Inthispaper,anewmethodfornumericallysolvingnonlinearconvection-dominateddiffusionproblemsisdevisedandanalysed.Thediscretetimeapproximationswithtimesteppingalongcharactcristicsarecstablishedandsolvedinspacesposscssingreproducingkernelfunctions.Ateachtimestep,theexactsolutionoftheapproximateproblemisgivenbyexplicitexpression.Thecomputationaladvantageofthismethodisthattheschemesareabsolutelystable,andareexplicitlysolvableaswell.Thestabilityanderrorestimatesarederived.Somenumericalresultsaregiven.

简介：ＴＨＥＵＮＩＱＵＥＮＥＳＳＡＮＤＣＯＮＴＩＮＵＯＵＳＤＥＰＥＮＤＥＮＣＥＦＯＲＣＨＡＲＡＣＴＥＲＩＳＴＩＣＣＡＵＣＨＹＰＲＯＢＬＥＭＯＦＰＡＲＴＩＡＬＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＬｕａｎＷｅｎｇｕｉ（栾文贵）（ＣｏｍｐｕｔｉｎｇＣｅｎｔ...

简介：Inthispaperweshallgivethecharacteristicdifferencemethodsfortwophasedisplacemeatprobleminnaturallyfracturedreservoirs.Weshallprovetheexistence,uniquenessoftheapproximatesolutionandaprioridiscreteL2-errorestimates.

简介：Inthispaper,weimplementalternatingdirectionstrategyandconstructasymmetricFVEschemefornonlinearconvection-diffusionproblems.ComparingtogeneralFVEmethods,ourmethodhastwoadvantages.First,thecoefficientmatricesofthediscreteschemeswillbesymmetricevenfornonlinearproblems.Second,sincethesolutionofthealgebraicequationsateachtimestepcanbeinvertedintothesolutionofseveralone-dimensionalproblems,theamountofcomputationworkissmaller.WeprovetheoptimalH1-normerrorestimatesoforderO(△t2+h)andpresentsomenumericalexamplesattheendofthepaper.

简介：Thesoftwareforoil-gastransportandaccumulationistodescribethehistoryofoil-gastransportandaccumulationinbasinevolution.Itisofgreatvalueinrationalevaluationofprospectingandexploitingoil-gasresources.Themathematicalmodelcanbediscribedasacoupledsystemofnonlinearpartialdifferentialequationswithmovingboundaryvalueproblem.Foragenericcaseofthethree-demensionalboundedregion,bithisthesis,theeffectsofgravitation、buoyancyandcapillarypressureareconsidered,weputforwardakindofcharacteristicfinitedifferenceschemesandmakeusethickandthingridstoformacompleteset,andofcalculusofvaviations,thechangeofvariable,thetheoryofpriorestimatesandtechniques,Optimalorderestimatesinl~2normarederivedfortheerrorinapproximateassumption,Thuswehavecompletelysolvedthewell-knowntheoreticalproblemproposedbyJ.Douglas,Jr.

简介：Inthiswork,systemofparabolicequationswithdiscontinuouscoefficientsisstudied.Thedomaindecompositionmethodmodifiedbyacharacteristicfiniteelementprocedureisapplied.Afunctionisdefinedtoapproximatethefluxesoninnerboundariesbyusingthesolutionatthepreviouslevel.Thustheparallelismisachieved.Convergenceanalysisanderrorestimatearealsopresented.

简介：Petroleumsciencehasmaderemarkableprogressinorganicgeochcmistryandintheresearchintothetheoriesofpetroleumorigin,itstransportandaccumulation.Inestimatingtheoil-gasresourcesofabasin,theknowledgeofitsevolutionaryhistoryandespeciallythenumericalcomputationoffluidflowandthehistoryofitschangesunderheatisvital.Themathematicalmodelcanbedescribedasacoupledsystemofnonlinearpartialdifferenticalequationswithinitial-boundaryvalueproblems.Thisthesis,fromactualconditionssuchastheeffectoffluidcompressibilityandthethree-dimensionalcharacteristicoflarge-scalescience-engineeringcomputation,weputforwardakindofcharacteristicfiniteelementalternating-directionschemesandobtainoptimalorderestimatesinL~2normfortheerrorintheapproximateassumption.

简介：Akindofsecond-orderimplicitfractionalstepcharacteristicfinitedifferencemethodispresentedinthispaperforthenumericallysimulationcoupledsystemofenhanced(chemical)oilproductioninporousmedia.Sometechniques,suchasthecalculusofvariations,energyanalysismethod,commutativityoftheproductsofdifferenceoperators,decompositionofhigh-orderdifferenceoperatorsandthetheoryofaprioriestimatesareintroducedandanoptimalordererrorestimatesinl~2normisderived.Thismethodhasbeenappliedsuccessfullytothenumericalsimulationofenhancedoilproductioninactualoilfields,andthesimulationresultsarequiteinterestingandsatisfactory.