共查询到19条相似文献,搜索用时 62 毫秒
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从信号处理角度考察Lubich系数,分析了Lubich系数的频域特性。设计了一种基于快速傅里叶逆变换(IFFT)的Lubich系数的快速算法。IFFT算法直接求解的Lubich系数不准确,在甚低阶运算时频域存在吉布斯效应,新算法利用零频赋值可有效减弱该效应。数值仿真结果表明,与Lubich准确系数相比,在一定真分数运算阶范围内,新算法求得的Lubich近似系数构建数字分数微分器有更好的效果,且新算法计算复杂度低,运算效率高。 相似文献
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文中提出三种求解高阶逼近任意运算阶的Grünwald-Letnikov分数阶微分器系数的快速算法,表述了算法的实现原理及对应的推导公式,并对其进行运行时间统计和计算复杂度分析。与幂级数展开法、卷积计算法、复化Simpson数值逼近法和IFFT相比,快速算法可以在误差允许的范围内,降低求解Grünwald-Letnikov分数阶微分器系数的计算复杂度,从而提高执行效率。 相似文献
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频域模式格林函数是频域旋转对称矩量法(FDBoRMoM)各Fourier模式分量特有的格林函数,它是个急速振荡积分,振荡频率随模式数和电尺寸的增大而增大.能否快速计算这个振荡积分是提高FDBoRMoM效率的瓶颈,特别是平面波倾斜照射时.基于振荡核的谱估计和模式缩减技术,我们提出了一种模式格林函数的单区间自适应积分方法.该方法能够根据场源点位置自动确定是否需要作数值积分;如果需要,它可以自适应选择整个积分区间作单次Gauss积分时合适的采样点数;在保持很高计算精度的前提下,它具有自适应、高效和稳定的优点. 相似文献
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一阶逼近格林瓦尔-莱特尼科夫(G-L)加权系数的计算具有准确快速的递推公式,而高阶逼近鲁比希加权系数的求解则复杂度高,计算消耗时间长。本文通过傅里叶变换证明了鲁比希算子的逼近阶,并基于移位鲁比希算子提出一类四阶逼近的加权移位鲁比希差分(WSLD)算子。从数字信号处理角度分析WSLD算子滤波特性,设计基于WSLD算子的分数阶数字FIR微分滤波器并进行数值仿真验证。对比Al-Alaoui、鲁比希2种典型分数阶算子,结果表明,利用WSLD算子求解分数阶数字FIR滤波器滤波系数的算法简单、高效,且相对其他算子能有效减小吉布斯效应影响。 相似文献
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通过变量代换和积分路径的复平面变换,将类菲涅耳型振荡积分变换为非振荡型积分,所得积分的计算时间与振
荡频率成反变的关系,使得计算速度变为原来积分速度的几十到上百倍。而且,该方法所用到的仅为数学变换,几乎不
存在误差,很好的解决了类菲涅耳型振荡积分问题。 相似文献
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相比传统的基于整数阶微分的图像增强算子,分数阶微分增强算子能提升图像的高频边缘信息,且非线性保留图像纹理细节和平滑区域的中低频信息。文中根据Riemann-Liouville分数阶微分定义,构造了5×5大小的分数阶微分增强算子模板,同时采用传统的整数阶图像增强算子Sobel算子、Prewitt算子和Laplacian算子,分别对灰度图像和彩色图像进行图像增强处理实验。最后,引入图像熵的计算,对图像增强的结果进行熵值大小的计算与分析。随着分数阶微分阶次的增加,分数阶微分增强算子处理后的图像熵值呈上升趋势,说明图像的纹理细节信息得到了加强。 相似文献
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应用MATLAB实现数字水印算法 总被引:2,自引:0,他引:2
介绍了数字水印算法中常用的MATLAB函数,应用MATLAB语言实现了一个空间域数字水印算法的嵌入、提取和攻击过程,并给出了程序运行的结果. 相似文献
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Motion estimation in H.264/AVC, is done in two parts – integer motion estimation, and fractional motion estimation. Hardware reuse for both parts is inefficient due to the differences between them. In this paper we address the hardware reuse problem by proposing a, fast motion estimation algorithm as well as a pipelined FPGA-based, field programmable system-on-chip (FPSoC), for integer and fractional motion estimation. Our results show that the rate-distortion loss of our algorithm is insignificant when compared to full search in H.264/AVC. Its average Y-PSNR loss is 0.065 dB, its average percentage bit rate increase is 5 %, and its power consumption is 76 mW. Our FPSoC is hardware-efficient, even out-performing some state-of-the-art ASIC implementations. It can support up to high definition 1280?×?720p video at 24Hz. Thus, our proposed algorithm and architecture is suitable for delivery of high quality video on low power devices and low bit rate applications which typically use H.264/AVC baseline profile@levels 1–3.1. 相似文献
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Mapping functions forward is required in image warping and other signal processing applications. The problem is described as follows: specify an integer d 1, a compact domain D R
d, lattices L
1,L
2 R
d, and a deformation function F : D R
d that is continuously differentiable and maps D one-to-one onto F(D). Corresponding to a function J : F(D) R, define the function I = J F. The forward mapping problem consists of estimating values of J on L
2 F(D), from the values of I and F on L
1 D. Forward mapping is difficult, because it involves approximation from scattered data (values of I F
-1 on the set F(L
1 $#x22C2; D)), whereas backward mapping (computing I from J) is much easier because it involves approximation from regular data (values ofJ on L
2 D). We develop a fast algorithm that approximates J by an orthonormal expansion, using scaling functions related to Daubechies wavelet bases. Two techniques for approximating the expansion coefficients are described and numerical results for a one dimensional problem are used to illustrate the second technique. In contrast to conventional scattered data interpolation algorithms, the complexity of our algorithm is linear in the number of samples. 相似文献
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An algorithm for computing the correlations of Walsh functions is presented. Given indices j and p between 0 and 2n - 1, the algorithm computes the correlation between the jth and kth Walsh-Paley function at time differences t = i2-n, i =0,1,..., 2n - 1. These values specify the correlation completely as it varies linearly between these points. A Fortran program is shown. The time required to compute a complete 2n point correlation is approximately the same as that of a 2n point fast Walsh transform. 相似文献
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提出了一种设计稀疏FIR数字滤波器的快速算法.该算法是在文献[19]所提算法的基础上进行了适当的改进.所提算法有效解决了L1-L2优化问题,具有很快的收敛性,并且新算法解决了权衡参数的选取问题.应用该算法成功设计了一维与二维的FIR稀疏数字滤波器,并与非稀疏情况下的设计进行了比较,仿真结果也表明本文所提算法的有效性. 相似文献
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Spectral Two-Step Preconditioning of Multilevel Fast Multipole Algorithm for the Fast Monostatic RCS Calculation 总被引:3,自引:0,他引:3
Ping-Liang Rui Ru-Shan Chen Dao-Xiang Wang Yung E.K.-N. 《Antennas and Propagation, IEEE Transactions on》2007,55(8):2268-2275
A new spectral two-step preconditioning of multilevel fast multipole algorithm (MLFMA) is proposed to solve large dense linear systems with multiple right-hand sides arising in monostatic radar cross section (RCS) calculations. The first system is solved with a deflated generalized minimal residual (GMRES) method and the eigenvector information is generated at the same time. Based on this eigenvector information, a spectral preconditioner is defined and combined with a previously constructed sparse approximate inverse (SAI) preconditioner in a two-step manner, resulting in the proposed spectral two-step preconditioner. Restarted GMRES with the newly constructed spectral two-step preconditioner is considered as the iterative method for solving subsequent systems and the MLFMA is used to speed up the matrix-vector product operations. Numerical experiments indicate that the new preconditioner is very effective with the MLFMA and can reduce both the iteration number and the computational time significantly. 相似文献