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简介：Inthispaper,basedonthesymboliccomputingsystemMaple,thedirectmethodforLiesymmetrygroupspresentedbySen-YueLou[J.Phys.A:Math.Gen.38(2005)L129]isextendedfromthecontinuousdifferentialequationstothedifferential-differenceequations.Withtheextendedmethod,westudythewell-knowndifferential-differenceKPequation,KZequationand(2+1)-dimensionalANNVsystem,andboththeLiepointsymmetrygroupsandthenon-Liesymmetrygroupsareobtained.

简介：InordertodevelopthepracticalapproximationmodelssuitabletoflowfieldsatlowMachnumberwithlargetemperaturedifference,theinfluenceofdifferenceinapproximationmodelsonnumericalsolutionswasinvestigatedbysolvingthenaturalconvectioninthe3-Denclosureswithverticalsidewallsdifferentiallyheatedandtheheatedbottomwallusing3approximationmodels,thatisBoussinesqapproximation,lowMachNumberapproximationandapproximationmodelproposedbyMlaouah.Asresultsofthesimulation,theeffectsofthedifferencesinthethreeapproximationmodelsonthenumericalsolutionsbecomeclear.

简介：TheresearchonthenumericalsolutionofthenonlinearLelandequationhasimportanttheoreticalsignificanceandpracticalvalue.TosolvenonlinearLelandequation,thispaperoffersaclassofdifferenceschemeswithparallelnaturewhicharepurealternativesegmentexplicit-implicit(PASE-I)andimplicit-explicit(PASI-E)schemes.Italsogivestheexistenceanduniqueness,thestabilityandtheerrorestimateofnumericalsolutionsfortheparalleldifferenceschemes.TheoreticalanalysisdemonstratesthatPASE-IandPASI-Eschemeshaveobviousparallelism,unconditionallystabilityandsecond-orderconvergenceinbothspaceandtime.ThenumericalexperimentsverifythatthecalculationaccuracyofPASE-IandPASI-EschemesarebetterthanthatoftheexistingalternatingsegmentCrank-Nicolsonscheme,alternatingsegmentexplicit-implicitandimplicit-explicitschemes.ThespeedupofPASE-Ischemeis9.89,comparedtoclassicalCrank-Nicolsonscheme.ThustheschemesgivenbythispaperarehighefficientandpracticalforsolvingthenonlinearLelandequation.

简介：Adaptivegridmethodsareestablishedasvaluablecomputationaltechniqueinapproximatingeffectivelythesolutionsofproblemswithboundaryorinteriorlayers.Inthispaper,wepresenttheanalysisofanupwindschemeforsingularlyperturbeddifferential-differenceequationonagridwhichisformedbyequidistributingarc-lengthmonitorfunction.Itisshownthatthediscretesolutionobtainedconvergesuniformlywithrespecttotheperturbationparameter.Numericalexperimentsillustrateinpracticetheresultofconvergenceprovedtheoretically.

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简介：介绍为菲希尔构造了有限差别计划的一个班的研究部分微分方程。逻辑方程的解决方案的性质；高保真度算法的建设；数字方法和preliminaries。

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简介：基于非破坏性的检查的实际状况，合成散布的计算模型被使用三维的一半空间建立有限差别时间领域，和蒙特卡罗方法被用来在建议计划与粗糙解决光表面的问题。而且，缺点粒子为一种更复杂的状况作为周期的粒子被观察。以便在光表面内获得缺点的散布贡献，差别雷达十字节被增加进模型在数字，分离距离，不同深度和缺点的不同材料的效果上分析选择计算。不同事件角度的效果也被讨论。数字结果详细被分析表明最好的位置由为事件角度在固定的度的步检测在光表面发现缺点。

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

简介：Todealwiththestaircaseapproximationprobleminthestandardfinite-differencetime-domain(FDTD)simulation,thetwo-dimensionalboundaryconditionequations(BCE)methodisproposedinthispaper.IntheBCEmethod,thestandardFDTDalgorithmcanbeusedasusual,andthecurvedsurfaceistreatedbyaddingtheboundaryconditionequations.Thus,whilemaintainingthesimplicityandcomputationalefficiencyofthestandardFDTDalgorithm,theBCEmethodcansolvethestaircaseapproximationproblem.TheBCEmethodisvalidatedbyanalyzingnearfieldandfarfieldscatteringpropertiesofthePECanddielectriccylinders.TheresultsshowthattheBCEmethodcanmaintainasecond-orderaccuracybyeliminatingthestaircaseapproximationerrors.Moreover,theresultsoftheBCEmethodshowgoodaccuracyforcylinderscatteringcaseswithdifferentpermittivities.

简介：Thesub-land/sub-pitaffectsthecharacteristicofthetrackingerrorsignalwhichisgeneratedbytheconventionaldifferentialphasedetection(DPD)methodinthesignalwaveformmodulationmulti-level(SWML)read-onlydisc.Tosolvethisproblem,thispaperproposesanewtrackingerrordetectionmethodusingamplitudedifference.Basedonthediffractiontheory,theamplitudedifferenceisproportionaltothetrackingerrorandisfeasibletobeusedforobtainingtheoff-trackinformation.Theexperimentalsystemoftheamplitudedifferencedetectionmethodisdeveloped.Theexperimentalresultsshowthatthetrackingerrorsignalderivedfromthenewmethodhasbetterperformanceinuniformityandsignal-to-noiseratiothanthatderivedfromtheconventionalDPDmethodintheSWMLread-onlydisc.

简介：Thefinite-dmerencetime-domam（FDTD）methodisproposedforanalyzingthesurfaceacousticwave（SAW）propagationintwo-dimensional（2D）piezoelectricphononiccrystals（PCs）atradiofrequency（RF）,andalsoexperimentsareestabhshedtodemonstrateitsanalysisresultofthePCs’bandgaps.TheFDTDmethodtakesthepiezoelectriceffectofPCsintoaccount,inwhichperiodicboundaryconditionsareusedtodecreasememory/timeconsumptionandtheperfectlymatchedlayerboundaryconditionsareadoptedastheSAWabsorberstoattenuateartificialreflections.TwoSAWdelaylinesareestabhshedwith/withoutpiezoelectricPCslocatedbetweeninterdigitaltransducers.Byremovingseveralechoeswithwindowgatingfunctionintimedomain,delaylinestransmissionfunctionisachieved.ThePCs’transmissionfunctionsandbandgapsareobtainedbycomparingtheminthesetwodelaylines.WhenAluminum/128°YX-LiNbO3isadoptedasscatterandsubstratematerial,thePCs’bandgapiscalculatedbythisFDTDmethodandCOMSOLrespectively.ResultsshowthatcomputationalresultsofFDTDagreewellwithexperimentalresultsandarebetterthanthatofCOMSOL.

简介：Wereporttheinvestigationontheperformanceofanamplificationassisteddifferencefrequencygeneration(AA-DFG)systemdrivenbypulsedpumpandcontinuous-waveprimarysignallasers.AmonolithictandemlithiumniobatesuperlatticewasemployedasthenonlinearcrystalwithauniformgratingsectionfortheDFGprocess,followedbyachirpsectionfortheopticalparametricamplificationprocess.Theimpactsofpumppulseshape,primarysignalpower,inputbeamdiameter,andcrystalstructureonthepump-to-idlerconversionefficiencyoftheAA-DFGsystemwerecomprehensivelystudiedbynumericallysolvingthecoupledwaveequations.Itisconcludedthatsquarepumppulseandhighprimarysignalpowerarebeneficialtohighpump-to-idlerconversionefficiency.Inaddition,tighterinputbeamfocusandsmallerDFGlengthproportioncouldredeemthereductioninconversionefficiencyresultingfromwideracceptancebandwidthsfortheinputlasers.Webelievethatsuchsystemscombiningthemeritsofhighstabilityinheritedfromcavity-freeconfigurationandhighefficiencyattributedfromthecascadednonlinearconversionshouldbeofgreatinteresttoawidecommunity,especiallywhenthepulseshapingtechniqueisincorporated.

简介：Asystemofm(≥2)linearconvection-diffusiontwo-pointboundaryvalueproblemsisexamined,wherethediffusiontermineachequationismultipliedbyasmallparameterεandtheequationsarecoupledthroughtheirconvectiveandreactivetermsviamatricesBandArespectively.Thissystemisingeneralsingularlyperturbed.Unlikethecaseofasingleequation,itdoesnotsatisfyaconventionalmaximumprinci-ple.CertainhypothesesareplacedonthecouplingmatricesBandAthatensureexis-tenceanduniquenessofasolutiontothesystemandalsopermitboundarylayersinthecomponentsofthissolutionatonlyoneendpointofthedomain;thesehypothesescanberegardedasastrongformofdiagonaldominanceofB.Thissolutionisdecomposedintoasumofregularandlayercomponents.Boundsareestablishedonthesecompo-nentsandtheirderivativestoshowexplicitlytheirdependenceonthesmallparameterε.Finally,numericalmethodsconsistingofupwindingonpiecewise-uniformShishkinmeshesareprovedtoyieldnumericalsolutionsthatareessentiallyfirst-orderconver-gent,uniformlyinε,tothetruesolutioninthediscretemaximumnorm.NumericalresultsonShishkinmeshesarepresentedtosupportthesetheoreticalbounds.

简介：本文中的“税”，除另有说明外，均专指企业所得税。一、负债的计税基础、暂时性差异和递延所得税的一般原理（一）负债的计税基础《企业会计准则第18号——所得税》（以下简称18号准则）规定：负债的计税基础，是负债的账面价值减去未来期间计算应纳税所得额时按照税法规定可予抵扣的金额。

简介：现有文献关于空间差异环境专利授权的最优合同基于固定费与可变费，而不是更一般的授权合同。针对这一问题，分析了厂商间的两部制最优专利授权策略。无论专利大小如何，授权合同同时包括固定费与可变费项，不授权不是最优的。专利对内部人的激励高于外部人。与专利发明之前比较，专利增加社会福利但不增加消费者剩余。