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简介:可变的步尺寸的新多项式明确的表达线性multistep方法被介绍,在每个k步方法被k的一个固定集合描绘的地方-1或k参数。这构造包括最大的顺序的所有方法(p=k为生硬,并且p=k+1为nonstiff问题)。由建设支持时间步adaptivity,新明确的表达不基于扩大古典固定的步尺寸方法;相反古典的方法是在一个统一框架以内修理了步尺寸限制被获得。方法在Matlab被实现,与本地错误评价和大量步尺寸控制器。这为处于现实主义的运作的条件调查并且比较不同multistep方法提供一个平台。计算实验证明新multistep方法构造和实现有利地比作存在软件,尽管可变顺序还没被包括了。
简介:Theinversescatteringproblemsaretodetectthepropertyofobstaclesfromthemeasurementsoutsidetheobstacles.Oneofimportantresearchareasinthistopicistherecoveryofboundarypropertyforimpenetrableobstacles.Inthispaper,wewouldliketogiveabriefreviewabouttherecentlydevelopedsingularsourcemethods.Therearethreedifferentmethodsinthiscategory,namely,linearsamplingmethod,pointsourcemethodandprobemethod.Wealsopresentsomerecentnewresultsabouttheprobemethod.
简介:SomepeoplearesuspiciousoforalEnglishlearningfortheyhavebeenaccustomedtotheoldtraditionalclassroomtraining.Thispaperdiscussessomenewteachingtechniquesinoralclass,whichbreaksthetraditionalteachingmethods.Ifteachersareawareoftheadvantagesofthesenewmethodsandputthemintopractice,thenwecancreatealivelyandnaturalatmospheresothatthestudentswilllosetheirinhibitionandlearnEnglishhappily.Themainpointofthispaperisthatthebestteachingmethodcanproducethebesteffectanditshouldbeacombinationofsomeflexibleandvariousapproachesratherthanonlyonesingleteachingmethodaswellasthecooperationofteacherandstudents.
简介:TeachingvocabularyTherearedifferentwayswecanusetoteachvocabularytochildren.Forexample,wecanuserealobjectswhenteachingschoolthings,suchas"book","pen","pencil","ruler",etc.Canweuserealobjectstoteach"car","train",and"plane"?Alsohowcanweteachwordssuchas"happy","excited","sad","tired",etc.?Lookatthefollowinggroupsofwordsanddis-cusswhattypesofwordstheyareandwaysofteachingthem.
简介:AclassofparallelnonlinearmultisplittingAORmethodsissetupbydirectlymultisplittingthenonlinearmappingF:DCR^n→R^nforsolvingthenonlinearsystemofequationsF(x)=0.Thedifferentchoicesoftherelaxationparameterscanyieldalltheknownandalotofnewrelaxationmethodsaswellasalotofnewrelaxationparallelnonlinearmultisplittingmethods.Thetwo-sidedapproximationpropertiesandtheinfluencesonconvergencefromtherelaxationparametersaboutthenewmethodsareshown,andthesufficientconditionsguaranteeingthemethodstoconvergegloballyarediscussed.Finally,alotofnumericalresultsshowthatthemethodsarefeasibleandefficient.
简介:Weintroducemultilevelaugmentationmethodsforsolvingoperatorequationsbasedondirectsumdecompositionsoftherangespaceoftheoperatorandthesolutionspaceoftheoperatorequationandamatrixsplittingscheme.Weestablishageneralsettingfortheanalysisofthesemethods,showingthatthemethodsyieldapproximatesolutionsofthesameconvergenceorderasthebestapproximationfromthesubspace.Theseaugmentationmethodsallowustodevelopfast,accurateandstablenonconventionalnumericalalgorithmsforsolvingoperatorequations.Inparticular,forsecondkindequations,specialsplittingtechniquesareproposedtodevelopsuchalgorithms.Thesealgorithmsarethenappliedtosolvethelinearsystemsresultingfrommatrixcompressionschemesusingwavelet-likefunctionsforsolvingFredholmintegralequationsofthesecondkind.Forthisspecialcase,acompleteanalysisforcomputationalcomplexityandconvergenceorderispresented.Numericalexamplesareincludedtodemonstratetheefficiencyandaccuracyofthemethods.IntheseexamplesweusetheproposedaugmentationmethodtosolvelargescalelinearsystemsresultingfromtherecentlydevelopedwaveletGalerkinmethodsandfastcollocationmethodsappliedtointegralequationsofthesecondkind.Ournumericalresultsconfirmthatthisaugmentationmethodisparticularlyefficientforsolvinglargescalelinearsystemsinducedfromwaveletcompressionschemes.
简介:Thispaperfirstestablishesthepriorglobedynamicalmodelbygeophysics,whichisasolidearthelasticdeformationmodel.Then,theparametersoftheglobedynamicmodelcanbeobtainedbyinvertingthegeodeticdata.Theinversemethodcanbeusedinseismologyandgeology,andtomakeearthquakeprediction.
简介:ConsiderthelinearsystemAx=b,(1)whereA∈Rn×nisnonsingular.TheadditiveSchwarzmethodwasintroducedinthelastcentury.Recently,themethodhasbeenusedforsolvinggeneralalgebraicsystemoflinearequations(1)inparal-lelcomputer(see[1]).Thisiterativemethodcanbeconsideredasageneralmultisplit-ting,inwhichthecorrespondingiteratesxn,l,l=1,2,…,k,aregivenby
简介:Inthisreview,weintendtoclarifytheunderlyingideasandtherelationsbetweenvariousmultigridmethodsrangingfromsubsetdecomposition,toprojectedsubspacedecompositionandtruncatedmultigrid.Inaddition,wepresentanovelgloballyconvergentinexactactivesetmethodwhichiscloselyrelatedtotruncatedmultigrid.Thenumericalpropertiesofalgorithmsarecarefullyassessedbymeansofadegenerateproblemandaproblemwithacomplicatedcoincidenceset.
简介:Thispaperdealswiththenumericalsolutionofinitialvalueproblemsforpantographdifferentialequationswithvariabledelays.Weinvestigatethestabilityofonelegθ-methodsinthenumericalsolutionoftheseproblems.Sufficientconditionsfortheasymptoticstabilityofθ-methodsaregivenbyFourieranalysisandErgodictheory.
简介:土壤体积密度的测量为理解土壤的物理、化学、生物的性质是重要的。精确、快速的土壤体积密度测量技术在农业试验性的研究起一个重要作用。这评论是存在测量方法的一篇全面摘要并且为未来开发评估他们的优点,劣势,错误的潜在的来源,和方向。这些技术能广泛地作为直接、间接的方法被分类。直接方法包括核心,土块,和挖掘采样,而间接方法包括放射和回归途径。核心方法最广泛地被使用,但是为采样使用多重土壤深度耗时、困难。coring柱体的尺寸使用了,操作员经验,采样深度,并且在原处显著地玷污潮湿内容影响它的精确性。土块方法是合适的因为有重黏土的使用,和它的精确性依赖于设备刻度,弄干时间,和操作员经验,但是这个过程复杂、耗时。挖掘技术最通常被用来评估森林土壤的体积密度,但是把他们不能与大毛孔在土壤被使用,他们的测量精确性被土壤质地和分析的类型强烈影响的主要限制选择。间接方法看起来比直接途径有更大的精确性,但是有更高的费用,是更复杂的,并且要求更大的操作员经验。一如此的途径使用gamma放射,和它的精确性被土壤深度强烈影响。当他们能做间接大小,回归方法是节俭的,但是这些取决于土壤质地和有机物内容和地理、气候的性质的好、优秀数据。另外,它的精确性象大多数另外的途径一样,与采样深度减少。