HIGH ACCURACY ANALYSIS FOR FIRST ORDER HYPERBOLIC EQUATIONS BY PETROV-GALERKIN METHODS

1.IntroductionInthispaper,weareconcernedwiththefiniteelementmethodforthefollowingfirstorderhyperbolicequationwithsomeinitial--boundaryconditionwheref,gandvaresufficientlysmoothgivenfunctions.ItiswellknownthatthestandardGalerkinfiniteelementmethodisnotasvalidtothefirstorderhyperbolicproblemsasitistotheellipticandtheparabolicproblems.TheaccuracyofGalerkinll]solutionsfortheabetorderhyperbolicproblems,roughlyspeaking,losesoneorderwithrespecttotheaccuracyofthefiniteelemelltspaces.Moreover,Galerki…     

THE SPLITTING EXTRAPOLATION FOR FINITEELEMENT METHOD

1.IntroductionDespitethesignificantprogressmadeindigitalcomputersandcomputationalmethodsoaferthelasttwodecades,computationalworkaswellascomputerstoragerequiremelltintheappliedfieldissogreatthatsuper-computersarenotabletoaft'ord.111recentyears)thehotpoilltsincomputationalmathematicsarehowtodevelopanealcomPlltationalmethodwhichwouldfulfilthefollowingrequirelllents;1)ItshouldbeaparallelcomputationalIned]'>(lwhichcan11eimplementedonrnultiprocessorcomputersreqlliringminimalcommunicationanloll!{pro(…     

EIGENVALUE EXTRAPOLATION FORBIQUADRATIC FINITE ELEMENT APPROXIMATION IN RECTANGULAR DOMAIN

1.IntroductionItiswellknownthattheextrapolationmethodscanimprovetheaccuracyoffiniteelementsolutionandarewellstudiedinmanypapers.Wereferto[1--4]forafundamentalworkonasymptoticerrorexpansionsandextrapolationsandto[5]forasurveyonextrapolationtechniques.Forth…     

A MULTI－PARAMETER SPLITTING EXTRAPOLATION AND A PARALLEL ALGORITHM FOR PARABOLIC PROBLEM

ＡＭＵＬＴＩ－ＰＡＲＡＭＥＴＥＲＳＰＬＩＴＴＩＮＧＥＸＴＲＡＰＯＬＡＴＩＯＮＡＮＤＡＰＡＲＡＬＬＥＬＡＬＧＯＲＩＴＨＭＦＯＲＰＡＲＡＢＯＬＩＣＰＲＯＢＬＥＭＬＩＵＸｉａｏｑｉ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＸｉａｎｇｔａｎＴｅａｃｈ...     

EXTRAPOLATION FOR FINITE ELEMENT METHODS OF THE FIRST KIND FREDHOLM INTEGRAL EQUATIONS

In this paper,a numerical analysis of finite element methods for Fredholm equationsof the first kind,which is based upon regularization,is made.It shows that extrapolationalgorithms can accelerate the convergence of approximate solutions.     

THE EXTRAPOLATION METHOD FOR A CLASS OF NON-SMOOTH FREDHOLM INTEGRAL EQUATIONS

For a class of non-smooth Fredholm integral equations we prove thatRichardson extrapolation method can be used to increase accuracy for finite ele-ment methods.On the basis of local refinement mesh,a superconvergence result isshown.Our theory also covers a class of non-smooth Wiener-Hopf equations andan application includes the calculation in certain linear elastic fracture problems.     

协整系统的贝叶斯推断

讨论协整系统的检验问题．提出一种基于协整系统误差校正模型的贝叶斯协整检测方法，并通过模拟实验说明贝叶斯方法的有效性．     

CORRECTION FOR COLLOCATION SOLUTIONS OF WIENER－HOPF EQUATIONS

ＣＯＲＲＥＣＴＩＯＮＦＯＲＣＯＬＬＯＣＡＴＩＯＮＳＯＬＵＴＩＯＮＳＯＦＷＩＥＮＥＲ－ＨＯＰＦＥＱＵＡＴＩＯＮＳ￥ＳＨＩＪｕｎ；ＬＩＮＱｕｎ（ＩｎｓｔｉｔｕｔｅｏｆＳｙｓｔｅｍｓＳｃｉｅｎｃｅ，ＡｃａｄｅｍｉａＳｉｎｉｃａ，Ｂｅｉｊｉｎｇ１０００８０，...     

季节协整系统的贝叶斯推断

讨论季节协整系统的检验问题．提出了一种基于季节协整系统误差校正模型的贝叶斯季节协整检测方法,并通过模拟实验说明贝叶斯方法的有效性．     

DEFECT CORRECTION FOR FINITE ELEMENT GRADIENT

A defect correction scheme of fourth order accuracy for linear finite element gradient is proposed in this note.This extends the Rannacher's scheme for finite element solution to gradient and can compete with superconvergence from quadratic elements.     

GLOBAL SUPERCONVERGENCE ANALYSIS OF WILSON ELEMENT FOR SOBOLEV AND VISCOELASTICITY TYPE EQUATIONS

In this paper the Wilson nonconforming finite element is employed to solve Sobolev and viscoelasticity type equations. By means of post-processing technique, global superconvergence estimates are obtained for quasi-uniform rectangular meshes. Finally, an error correction scheme is presented.     

AN ADAPTIVE TRUST REGION METHOD FOR EQUALITY CONSTRAINED OPTIMIZATION

In this paper, a trust region method for equality constrained optlmization based on nondiferentiable exact penalty is proposed. In this algorithin, the trail step is characterized by computation of its normal component being separated from computation of its tangential component, i.e., only the tangential component of the trail step is constrained by trust radius while the normal component and trail step itself have no constraints. The other main characteristic of the algorithm is the decision of trust region radius. Here, the decision of trust region radius uses the information of the gradient of objective function and reduced Hessian. However, Maratos effect will occur when we use the nondifferentiable exact penalty function as the merit function. In order to obtain the superlinear convergence of the algorithm, we use the twice order correction technique. Because of the speciality of the adaptive trust region method, we use twice order correction when p= 0 (the definition is as in Section 2) and this is different from the traditional trust region methods for equality constrained opthnization. So the computation of the algorithm in this paper is reduced. What is more, we can prove that the algorithm is globally and superlinearly convergent.     

地炮定位雷达中的弹道外推及误差估计

本文结合我国正在研制的某型地炮侦校雷达的研究,设计了一个用于弹道外推的卡尔曼滤波器,介绍了依用卡尔曼滤波器估计出的弹丸飞行参数外推出敌方炮位的方法.首次提出了估计外推误差的方法.本文还给出了弹道外推及误差估计的计算机模拟结果.     

用空间信号外推提高阵处理分辨力的一种新方法

本文在空间域的带限信号外推的基础上,提出了一种新的提高阵处理分辨力的方法。为了克服阵元间距为半个载波波长时空间域带限信号外推的困难,文中利用了一种预处理方法。模拟结果表明新方法比现有方法具有更高的分辨力。     

MULTILEVEL CORRECTION FOR COLLOCATION SOLUTIONS OF VOLTERRA NONL INEARINTEGRO-DIFFERENTIAL EQUATIONS

1. IntroductionWe consider a Volterra integro-differential equationwith initial condition u(0) = not where f, P, k are continuous on their respective domainsJ, JxR and axs (n:~ {(t,s): 05s5t5T}) such that (1.l) possesses a unique solutionu E C'(J).It has been shown in [1] that the collocation approximation for (1.1) by discolltinuous piece--wise polynomial spline collocation at the Gauss points restore optimal local superconvergenceat the knots but does not yield global superconvergence on…     

一种高分辨率谱估计与数据外推的快速算法

利用信号频谱幅度分布的先验信息，对短时数据序列信号提出了一种实现高分辨率谱估计和数据序列外推的快速算法。该算法利用了算子矩阵的特殊结构，采用简单、快速的矩阵求逆算法，使算法的运算量和数据存储容量大幅度下降。给出了算法在高分辨率谱估计及数据序列外推中的应用实例和仿真结果，证实了该算法的优良性能。     

短波跳频FH/QDPSK系统信道自适应监测的研究(Ⅰ)

基于短波跳频FH/QDPSK系统的FFT解调 ,利用FFT解调的结果 ,提出了在瑞利衰落信道中对信道的比特误码率BER进行实时自适应监测方法 ,该方法利用伪错外推较好地解决了在较短的监测时间获取较精确的监测结果。模拟结果表明 :采用伪错的线性外推算法 ,其估值的最大绝对误差不超过 0 89,最大相对误差不超过35 7%。     

曲线拟合滤波在无人机导航数据处理中的应用

针对无人机导航数据处理强实时性的要求,提出了一种利用曲线拟合外推法进行数据滤波的方法。该方法基于量测信息连续变化的特点,利用曲线拟合外推法得到量测信息的近似理论值,根据量测信息相对于近似理论值的偏差程度对其进行分类,按提出的数据处理结构模型分别进行滤波。该方法无需量测信息的先验知识,能够准确地获得实时导航信息,并且在小噪声扰动时处于稳定,对于过失误差有较强的鲁棒特性。通过仿真实验证明了该算法的有效性。     

雷达目标有限频率响应数据的结构窗函数约束外推

本文针对目标成像与目标识别这一应用背景，提出了一种以目标距离结构窗函数为约束的限带频率响应数据的外推方法，这种方法首先根据常规的ＦＦＴ分析，获取目标的距离结构先验信息，然后根据误差能量逐步减少原则，对外推数据进行迭代求解；为改善抗杂波性能，利用结构窗函数对信号进行了准匹配滤波处理。与常规外推法相比，它具有稳健性好、外推误差小、抗杂波性能好等优点，适用于在发射波形带宽不足的情况下，进行高分辨成像。     

目标电磁散射的面中心立方体网格FDTD方法

基于面中心立方体(face-centered cube, FCC)网格的空间结构, 由麦克斯韦方程出发, 推导了基于FCC网格的单轴各向异性介质完全匹配层(uniaxial anisotropic media perfectly matched layer, UPML)吸收边界条件以及近-远场外推边界条件的三维迭代式。通过典型算例, 先后验证了基于面中心立方体网格的时域有限差分(FCC-finite difference time domain, FCC-FDTD)方法的UPML吸收边界条件和近远场外推边界条件的正确性。最后通过计算金属球的后向雷达散射截面(radar cross section, RCS)比较了FCC-FDTD方法与传统FDTD方法的计算精度, 结果显示FCC-FDTD方法具有更高的计算精度。