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1.
块三对角矩阵的并行局部块分解预条件   总被引:5,自引:0,他引:5  
该文首先分析了并行局部块分解预条件的特征分布,分析表明其与串行局部块分解预条件的特征分布基本相当,从而从理论上保证了利用该预条件进行并行计算时的高效性.其次分析了利用该预条件进行并行计算时影响加速比的因素,由此说明了当问题规模不大而处理机台数增加时,计算效率必然逐渐下降的原因.最后在由6台微机连成的机群系统上将该预条件与利用多分裂技术构造的多种预条件进行了比较,实验结果说明该预条件效率高于其它预条件方法.同时在某巨型机上进行的实验表明对处理机台数比较多时,该预条件也仍然很有效.  相似文献   

2.
赵长宽  姬彦巧 《计算机工程与设计》2006,27(23):4540-4542,4546
在分析了AutoCAD的块和属性块定义技术的基础上,研究如何在SolidEdge中实现类似技术的方法。提出在SolidEdge中以组对象为基础构建块,以其属性集实现块属性的存储,并应用UML描述了主要问题的算法过程。基于COM技术实现了创建块、插入块、块分解、块信息处理的方法,以构建的一个标准图纸自动生成系统为例,说明块技术应用情况。  相似文献   

3.
大系统块对角优分解   总被引:2,自引:0,他引:2  
赵明  陈雪波 《控制与决策》2000,15(5):585-588
以系统状态方程为模型,提出将系统矩阵A块三角分散后,通过非平衡补偿使其具有块对角优形式的分解该当。仿真实例证明该方法是可行的,它可简化模型为块对角型,为大系统分散控制设计与实现及并行处理提供了实用手段。  相似文献   

4.
描述采用16位定点DSP处理器TMS320C54X系列实现线性回波消除器的方法。详细讨论两种不同的自适应横向回波消除滤波器的具体实现,即块更新和归一化最小均方法 NLMS(随机梯度法)。给出LEC两种实现方式内核代码周期数及内存要求的估值,测试并记录LEC两种算法基于抽头数和迭代步长的误差输出。结合DSP芯片的特征,该方法充分有效地利用了其软硬件资源。经验证,该方案易于实现和控制,性能以及可靠性均得到大幅增强。对于两种算法的选择,应在实际的电话网络环境中,根据工业标准测试作最终判断。  相似文献   

5.
提出了求解系数矩阵为块三对角的线性方程组的一种适合于MIMD分布式存储的并行算法,该算法以系数矩阵分解为基础,充分利用了系数矩阵结构的特殊性,进行了近似处理,使整个计算过程只在相邻处理机间通信两次,具有很高的并行效率,并在理论上给出了该算法成立的充分条件。最后,在HPrx2600集群上进行数值试验,结果表明,加速比呈线性增加,并行效率达到90%以上。  相似文献   

6.
燕必东  许卓群 《软件学报》1997,8(A00):56-64
分形图象压缩是一个比较新的图象压缩方法,不于同常规的压缩方法,它旨在减少块间冗余度。该方法由Barnsley于1988年正式提出,由于Jacquin于1989年实现,由于Jacquin的方法在压缩率和压缩时间方面存在缺陷,许多人从不同的方面对其进行了改进。  相似文献   

7.
在基于运动估计和预测编码的视频编码方案中,有一种简单而有效的快速实现方法——零块判决方法,H.264/AVC使用的也是基于运动估计和预测编码的视频编码方案,所以也可以运用零块判决方法来加快其编码速度.根据H.264/AVC视频编码标准的新特点,对其中的零块判决阈值进行了推导,提出了新的适合于H.264/AVC的零块判决方法,并进行了仿真测试,实验结果表明,在中低码率的视频编码中,该方法在编码效率基本保持不变的条件下,编码时间减少了20%~47%.  相似文献   

8.
小波域三维块匹配图像去噪   总被引:3,自引:0,他引:3       下载免费PDF全文
提出了一种关于图像去噪的三维块匹配算法(BM3D算法)的改进算法。它不仅保留了三维块匹配算法好的性质,而且最大的优点是能大大减少计算量,缩短运算时间。算法包括三个步骤:首先,对含噪图像进行小波分解;其次,对小波分解后的高频分量用三维块匹配(BM3D)算法进行去噪处理;最后,用处理后的结果进行小波重构得到去噪图像。给出了该算法的详细实现过程,并把它与以前的三维块匹配算法进行了比较。结果表明,改进后的算法,不但保留了三维块匹配算法在去噪方面好的性质,而且大大减少了运算量。  相似文献   

9.
提出一种多变量传递函数矩阵辨识的二级QR分解算法,避免了子系统辨识方法 对可测数据的重复处理;在不扩大维数的条件下,获得使总体损失函数最小的估计值.该算法 与HOUSEHOLDER变换的快速递推算法结合,不仅大大地减少了辨识所需的运算量,而且 可减少LS算法中增益矩阵计算的误差积累和传递,提高辨识精度.  相似文献   

10.
面向口语翻译的双语语块自动识别   总被引:1,自引:0,他引:1  
程葳  赵军  刘非凡  徐波 《计算机学报》2004,27(8):1016-1020
语块识别是实现“基于语块处理方法”的基础 .目前 ,针对单语语块的研究成果已有很多 ,但机器翻译更需要双语相关的语块分析 .该文根据口语翻译的实际需要 ,提出了“双语语块”的概念 .并在此基础上 ,实现了一种针对并行语料库进行双语语块自动识别的新方法 .该方法将统计和规则相结合 ,可同时保证双语语块的语义特性和句法规范 .通过在一个 6万句的旅馆预定领域口语语料库中的实验可以看出 ,该方法对汉英并行语料的双语语块识别正确率可达到 80 %左右 .  相似文献   

11.
Based on a general splitting of the (1,1) leading block matrix, we first construct a general class of shift-splitting (GCSS) preconditioners for non-Hermitian saddle point problems. Convergence conditions of the corresponding matrix splitting iteration methods and preconditioning properties of the GCSS preconditioned saddle point matrices are analyzed. Then the GCSS preconditioner is specifically applied to the non-Hermitian saddle point problems arising from the finite element discretizations of the hybrid formulations of the time-harmonic eddy current models. With suitable choices of the splittings, the new GCSS preconditioners are easier to implement and have faster convergence rates than the existing shift-splitting preconditioner and its modified variant. Two numerical examples are presented to verify the theoretical results and show effectiveness of the new proposed preconditioners.  相似文献   

12.
This paper deals with preconditioners for solving linear systems arising from interior point methods, using iterative methods. The main focus is the development of a set of results that allows a more efficient computation of the splitting preconditioner. During the interior point methods iterations, the linear system matrix becomes ill conditioned, leading to numerical difficulties to find a solution, even with iterative methods. Therefore, the choice of an effective preconditioner is essential for the success of the approach. The paper proposes a new ordering for a splitting preconditioner, taking advantage of the sparse structure of the original matrix. A formal demonstration shows that performing this new ordering the preconditioned matrix condition number is limited; numerical experiments reinforce the theoretical results. Case studies show that the proposed idea has better sparsity features than the original version of the splitting preconditioner and that it is competitive regarding the computational time.  相似文献   

13.
Extremely large scale problems, modelled by partial differential equations, arise in various applications, and must be solved by properly preconditioned iterative methods. Frequently, the corresponding medium is heterogeneous. Recursively constructed two-by-two block matrix partitioning methods and elementwise constructed preconditioners for the arising pivot block and Schur complement matrices have turned out to be very efficient methods, and are analysed in this paper. Thereby special attention is paid to macroelementwise partitionings, which can be particularly efficient in the modelling of materials with large and narrow variations and can also provide efficient implementations on parallel computers.  相似文献   

14.
Regularizing preconditioners for accelerating the convergence of iterative regularization methods without spoiling the quality of the approximated solution have been extensively investigated in the last twenty years. Several strategies have been proposed for defining proper preconditioners. Usually, in methods for image restoration, the structure of the preconditioner is chosen Block Circulant with Circulant Blocks (BCCB) because it can be efficiently exploited by Fast Fourier Transform (FFT). Nevertheless, for ill-conditioned problems, it is well-known that BCCB preconditioners cannot provide a strong clustering of the eigenvalues. Moreover, in order to get an effective preconditioner, it is crucial to preserve the structure of the coefficient matrix. The structure of such a matrix, in case of image deblurring problem, depends on the boundary conditions imposed on the imaging model. Therefore, we propose a technique to construct a preconditioner which has the same structure of the blurring matrix related to the restoration problem at hand. The construction of our preconditioner requires two FFTs like the BCCB preconditioner. The presented preconditioning strategy represents a generalization and an improvement with respect to both circulant and structured preconditioning available in the literature. The technique is further extended to provide a non-stationary preconditioning in the same spirit of a recent proposal for BCCB matrices. Some numerical results show the importance of preserving the matrix structure from the point of view of both restoration quality and robustness of the regularization parameter.  相似文献   

15.
Iterative methods with variable preconditioners of additive type are proposed. The scaling factors of each summand in the additive preconditioners are optimized within each iteration step. It is proved that the presented methods converge at least as fast as the Richardson's iterative method with the corresponding additive preconditioner with optimal scaling factors. In the presented numerical experiments the suggested methods need nearly the same number of iterations as the usual preconditioned conjugate gradient method with the corresponding additive preconditioner with numerically determined fixed optimal scaling factors. Received: June 10, 1998; revised October 16, 1998  相似文献   

16.
《国际计算机数学杂志》2012,89(9):2091-2101
In this paper, based on the preconditioners presented by Cao [A note on spectrum analysis of augmentation block preconditioned generalized saddle point matrices, Journal of Computational and Applied Mathematics 238(15) (2013), pp. 109–115], we introduce and study a new augmentation block preconditioners for generalized saddle point matrices whose coefficient matrices have singular (1,1) blocks. Moreover, theoretical analysis gives the eigenvalue distribution, forms of the eigenvectors and its minimal polynomial. Finally, numerical examples show that the eigenvalue distribution with presented preconditioner has the same spectral clustering with preconditioners in the literature when choosing the optimal parameters and the preconditioner in this paper and in the literature improve the convergence of BICGSTAB and GMRES iteration efficiently when they are applied to the preconditioned BICGSTAB and GMRES to solve the Stokes equation and two-dimensional time-harmonic Maxwell equations by choosing different parameters.  相似文献   

17.
为了加快线性方程组的迭代法求解速度,提出了一类新预条件子,分析了相应的预条件AOR迭代法的收敛性。给出了当系数矩阵为严格对角占优的Z-矩阵时,AOR和预条件AOR迭代法收敛速度的比较结论。同时也给出了多级预条件迭代法的相关比较结果,推广了现有的结论。数值算例验证了文中结果。  相似文献   

18.
To solve nonsymmetric saddle point problems, the parameterized generalized shift-splitting (PGSS) preconditioner is presented and analyzed. The corresponding PGSS iteration method can be applied not only to the nonsingular saddle point problems but also to the singular ones. The convergence and semi-convergence of the PGSS iteration method are discussed carefully. Meanwhile, the spectral properties of the preconditioned matrix and the strategy of the choices of the parameters are given. Numerical experiments further demonstrate that the PGSS iteration method and the PGSS preconditioner are efficient and have better performance than some existing iteration methods and newly proposed preconditioners, respectively, for solving both the nonsingular and singular nonsymmetric saddle point problems.  相似文献   

19.

In literature, it has been reported that the convergence of some preconditioned stationary iterative methods using certain type upper triangular matrices as preconditioners are faster than the basic iterative methods. In this paper, a new preconditioned iterative method for the numerical solution of linear systems has been introduced, and the convergence analysis of the proposed method and an existing one have been done. Some numerical examples have also been given, which show the effectiveness of both of the methods.  相似文献   

20.
The goal of this paper is to compare several reanalysis methods for structural layout modifications with added degrees of freedom. These methods include the modified initial analysis methods, the modified initial analyses method with a scalar multiplier, and the preconditioned conjugate gradient method. These reanalysis methods are compared in terms of condition numbers of the preconditioned system and their computational accuracy. It is concluded in this paper that the preconditioner of the first method is not positive definite in general, while for the second method a positive definite preconditioner for a small scalar multiplier can be obtained, but the condition number of the preconditioned system is still large. For the third method, the condition numbers of the preconditioned system are significantly reduced, and highly accurate approximate solutions can be obtained in a few iterations.  相似文献   

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