简介:在这份报纸,我们学习联合与ILU(0)因式分解过滤分解的修改正切的频率的合成preconditioner。光谱合成preconditioner的性质被Fourier分析的途径检验。我们由合成preconditioner说明preconditioned矩阵的那个条件数字被Oasymptotically围住(...)在一个标准模型问题上。合成preconditioner的性能与与不连续的系数从PDE的discretization产生的几个问题上的另外的preconditioners相比。数字结果证明建议合成preconditioner的性能比另外的相对preconditioners优异。[从作者抽象]
简介:Inmagneticresonanceelastography,oneseekstoreconstructtheshearmodulusfrommeasurementsofthedisplacementfieldinthewholebody.Inthispaper,wepresentanoptimizationapproachwhichsolvestheproblembysimplyminimizingadiscrepancyfunctional.Inordertorecoveracomplexanomalyinahomogenousmedium,wefirstobservethattheinformationcontainedinthewavefieldshouldbedecomposedintotwoparts,a'near-field'partintheregionaroundtheanomalyanda'far-field'partintheregionawayfromtheanomaly.Aswillbejustifiedboththeoreticallyandnumerically,separatingthesescalesprovidesalocalandprecisereconstruction.
简介:Thepurposeofthispaperistostudythecascadicmultigridmethodforthesecondorderellipticproblemswithcurvedboundaryintwo-dimensionwhicharediscretizedbytheisoparametricfiniteelementmethodwithnumericalintegration.WeshowthattheCCGmethodisaccuratewithoptimalcomplexityandtraditionalmultigridsmoother(likesymmetricGauss-Seidel,SSORordampedJacobiiteration)isaccuratewithsuboptimalcomplexity.
简介:Inthispaper,finitevolumemethodonunstructuredmeshesisstudiedforaparabolicconvection-diffusionproblemonanopenboundedsetofR^d(d=2or3)withRobinboundarycondition.UpwindingapproximationsareadaptedtotreatboththeconvectiontermandRobinboundarycondition.Bydirectlygettingstartfromtheformulationofthefinitevolumescheme,numericalanalysisisdone.Byusingseveraldiscretefunctionalanalysistechniquessuchassummationbyparts,discretenorminequality,etal,thestabilityanderrorestimatesontheapproximatesolutionareestablished,existenceanduniquenessoftheapproximatesolutionandthe1stordertemporalnormandL^2andH^1spacialnormconvergencepropertiesareobtained.
简介:Asanimportantmodelinquantumsemiconductordevices,theSchrodinger-Poissonequationshavegeneratedwidespreadinterestsinbothanalysisandnumericalsimulationsinrecentyears.Inthispaper,wepresentGaussianbeammethodsforthenumericalsimulationoftheone-dimensionalSchrodinger-Poissonequations.TheGaussianbeammethodsforhighfrequencywavesoutperformthegeometricalopticsmethodinthattheformerareaccurateevenaroundcaustics.ThepurposesofthepaperarefirsttodeveloptheGaussianbeammethods,basedonourpreviousmethodsforthelinearSchrodingerequation,fortheSchrodinger-Poissonequations,andthenchecktheirvalidityforthisweakly-nonlinearsystem.
简介:在生物体之发光断层摄影术(BLT)问题,在从光信号的一个小动物内的生物体之发光来源分发在动物身体表面上检测了的一构造份量上。BLT问题是提出病的,经常,Tikhonov规则化被用来获得稳定的近似答案。在常规Tikhonov规则化,选择一个合适的规则化参数平衡近似解决方案的精确性和稳定性是关键的。在这份报纸,一个参数依赖者联合了基于的复杂边界方法(CCBM)Tikhonov规则化被用于放射的转移方程(RTE)管理的BLT问题。由适当地处于知更鸟边界条件调整参数,我们完成一个重要性质:调整答案关于规则化参数是一致地稳定的以便规则化参数能被选择完全基于答案精确性的考虑。分离纵标的有限元素的方法被用来计算数字答案。数字结果被提供说明建议方法的表演。
简介:TheextendedsystemofnondegeneratesimplebifurcationpointoftheNavier-Stokesequationsisconstructedinthispaper,duetoitsderivativehasablocklowertriangularform,wedesignaNewton-likemethod,usingtheextendedsystemandsplittingiterativetechniquetocomputetranscriticalnondegeneratesimplebifurcationpoint,wenotonlyreducescomputationalcomplexity,butalsoobtainquadraticconvergenceofalgorithm.
简介:Inthispaper,weconsiderthelocaldiscontinuousGalerkinmethod(LDG)forsolv-ingsingularlyperturbedconvection-diffusionproblemsinone-andtwo-dimensionalset-tings.TheexistenceanduniquenessoftheLDGsolutionsareverified.Numericalex-perimentsdemonstratethatitseemsimpossibletoobtainuniformsuperconvergencefornumericalfluxesunderuniformmeshes.Thankstotheimplementationoftwo-typedif-ferentanisotropicmeshes,i.e.,theShishkinandanimprovedgrademeshes,theuniform2p+1-ordersuperconvergenceisobservednumericallyforbothone-dimensionalandtwo-dimensionalcases.
简介:介绍在光滑的开的弧上为Helmholtz方程建议了第一个客气的不可分的方程的一个数字答案的研究。照方法使用了;数字例子。
简介:有多域和三倍的连接点的椭圆形的接口问题在工程和科学有宽应用程序。然而,角落奇特为大多数存在方法使它成为一个挑战性的问题。一个精确、有效的方法被需要。在这份报纸,有non-body-fitting格子的一个有效非传统的有限元素方法被建议与多域和三倍的连接解决椭圆形的接口问题。结果方程的线性系统是积极的明确如果为在领域的椭圆形的方程的矩阵系数是积极的明确。数字实验证明这个方法是在为piecewise的L标准精确的大约第二份订单光滑的答案。角落奇特能以一个方法被处理以便精确性不堕落。三倍的连接小心地被解决,它不需要被放在格子上,给我们的方法潜力对待没有改革网孔的动人的接口问题。