When determining the completion state of the main cable of a cable-way bridge, although the catenary theory can accurately consider the nonlinear mechanical effect of the cable, the iterative calculation is cumbersome...
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ISBN:
(纸本)9789811912603;9789811912597
When determining the completion state of the main cable of a cable-way bridge, although the catenary theory can accurately consider the nonlinear mechanical effect of the cable, the iterative calculation is cumbersome and not convenient for engineering applications. Although the calculation based on the parabola theory is simple, the calculation accuracy for long cables is low. In this paper, based on catenary theory and considering the calculation accuracy and avoiding iterative calculation, a fast algorithm for the completion state of the main cable of the wire rope cableway bridge is proposed. The results show that the bridge state can be quickly and accurately determined by approximating the horizontal component of the cable tension and avoiding multiple iterative calculations. The proposed algorithm can be used in engineering design and construction.
This paper describes a fast algorithm to compute local axial moments used in the detection of objects of interest in images. The basic idea is the elimination of redundant operations while computing axial moments for ...
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This paper describes a fast algorithm to compute local axial moments used in the detection of objects of interest in images. The basic idea is the elimination of redundant operations while computing axial moments for two neighboring angles of orientation. The main result is that the complexity of the recursive computation of axial moments becomes independent of the total number of computed moments at a given point, i.e., it is of the order O(N) where N is the size of the data set. This result is of great importance in computer vision since many feature extraction methods rely on the computation of axial moments. The use of this algorithm for fast object skeletonization in images by orthogonal regression fitting is described in detail, with the experimental results confirming the theoretical computational complexity. (C) 2003 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
The prediction error can be decreased by incorporating with high accuracy estimation and compensation, and the performance of compressed video can be improved. Two fast algorithms of fractional-pixel accuracy video mo...
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ISBN:
(纸本)0819444111
The prediction error can be decreased by incorporating with high accuracy estimation and compensation, and the performance of compressed video can be improved. Two fast algorithms of fractional-pixel accuracy video motion estimation are proposed in this paper. After half-pixel accuracy motion estimation, a high accuracy motion estimation can be calculated with the intermediate results. The algorithm is based on the intermediate results in half pixel accuracy motion estimation, and traditional fast block matching algorithms can also be implemented in half pixel accuracy. The arbitrary fractional-pixel accuracy motion estimation can be achieved directly, at the cost of small computational overhead. The approach described in this paper eliminates the systematic limitations of conventional block matching. Experimental results using typical video sequences show that the proposed algorithm can achieve better PSNR and lower bit rates in higher fractional pixel accuracy than in the half pixel motion estimation and compensation. These fast motion estimation algorithms provide methods for studying higher pixel accuracy motion estimation in video compression coding. The proper fractional pixel accuracy motion estimation and compensation by truncating the precise results will be the best way to achieve more efficiently video compensation and higher image quality.
An algorithm for the sound projection using multiple sources is presented. The source strength vector is obtained by using a fast estimation approach instead of the conventional eigenvalue decomposition (EVD) method. ...
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An algorithm for the sound projection using multiple sources is presented. The source strength vector is obtained by using a fast estimation approach instead of the conventional eigenvalue decomposition (EVD) method. The computation load is therefore greatly reduced, which makes the algorithm more efficient in practical applications.
This paper presents a fast algorithm for the computation of sliding conjugate symmetric sequency-ordered complex Hadamard transform (CS-SCHT). The algorithm calculates the values of window i + N/4 from those of window...
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This paper presents a fast algorithm for the computation of sliding conjugate symmetric sequency-ordered complex Hadamard transform (CS-SCHT). The algorithm calculates the values of window i + N/4 from those of window, one length-N/4 Walsh Hadamard transform (WHT) and one length-N/4 Modified WHT (MWHT). The proposed algorithm requires O(N) arithmetic operations, which is more efficient than the block-based algorithms of various transforms and the sliding FFT algorithm, but less efficient than the sliding WHT algorithms. Compared to the recently proposed sliding inverse SCHT (ISCHT) algorithm, the proposed algorithm is more efficient for real input but less efficient for complex input. The applications of the sliding CS-SCHT in transform domain adaptive filtering (TDAF) to complex signal channel equalization and real speech signal acoustic echo cancellation are also provided.
Efficient estimations of the carrier frequency offset (CFO) and channel are vital to orthogonal frequency division multiplexing (OFDM). In this paper, a new fast algorithm is proposed for estimating the CFO based on t...
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Efficient estimations of the carrier frequency offset (CFO) and channel are vital to orthogonal frequency division multiplexing (OFDM). In this paper, a new fast algorithm is proposed for estimating the CFO based on the pilot structure in [M. Morelli, U. Mengali, An improved frequency offset estimator for OFDM applications, IEEE Commun. Lett. 3(3) (1999) 75-77;H.K. Song, Y.H. You, J.H. Paik, Y.S. Cho, Frequency-offset synchronization and channel estimation for OFDM-based transmission, IEEE Commun. Lett. 4(3) (2000) 95-97]. The new method first identifies a coarse estimation of the CFO and then refines it by a least square (LS) method. It always gives a more accurate estimation than the multistage method in [H.K. Song, Y.H. You, J.H. Paik, Y.S. Cho, Frequency-offset synchronization and channel estimation for OFDM-based transmission, IEEE Commun. Lett. 4(3) (2000) 95-97] and is better than the method in [M. Morelli, U. Mengali, An improved frequency offset estimator for OFDM applications, IEEE Commun. Lett. 3(3) (1999) 75-77] at low SNR. It only slightly worse than the maximum likelihood estimator at high SNR. Furthermore, the proposed method can be used for CFO tracking. Also, in this paper, channel estimation by using the same pilot block is considered. The best values for the non-null subcarriers are found to optimize the channel estimation and peak to average power ratio (PAPR) simultaneously. Simulations demonstrate that the proposed methods are effective. (c) 2006 Elsevier B.V. All rights reserved.
The volume integral equation (VIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze antenna radiation in the presence of dielectric radomes. In solving the VIE, the radome is modeled...
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The volume integral equation (VIE) combined with the multilevel fast multipole algorithm (MLFMA) is applied to analyze antenna radiation in the presence of dielectric radomes. In solving the VIE, the radome is modeled by small volume cells of tetrahedron or hexahedron shape so that three-dimensional (3-D) complex radomes can be modeled accurately. When the induced volume current is determined by the method of moments, the total radiation is calculated by adding the induced current radiation to that of the antenna in the absence of the radome. The application of MLFMA reduced the computational complexity to a lower order and hence electrically large-sized radomes are analyzed. Numerical results are compared with the analytical solution for spherical shells with dipole array as excitations. The radiation patterns of dipole arrays in the presence of ogive, cone, and hemisphere radomes are also presented.
The fractional Fourier transform (FRT) is a recently developed tool for linear space-frequency (or time-frequency) signal processing. It is a generalisation of the Fourier transform, FT, has a simple optical implement...
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ISBN:
(纸本)0819453838
The fractional Fourier transform (FRT) is a recently developed tool for linear space-frequency (or time-frequency) signal processing. It is a generalisation of the Fourier transform, FT, has a simple optical implementation and can potentially find use wherever the FT is used. We discuss and compare the most popular fast algorithms currently being used (in the area of optical signal processing, OSP) to calculate the digital FRT. We develop theory for the discrete Linear Canonical Transform (LCT) of which the FRT is a special case. We then derive the fast Linear Canonical Transform (FLCT), a fast algorithm for its implementation using a similar approach as was done with the derivation of the fast Fourier Transform (FFT) for implementation of the Discrete Fourier Transform (DFT). The new algorithm is entirely independent of the FFT and is based purely on the properties of the LCT and FRT.
A new fast algorithm for the computation of discrete image moments is presented. The procedure is based on a discrete analogon of Green's theorem and is much faster than the method introduced earlier by Zakaria et...
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A new fast algorithm for the computation of discrete image moments is presented. The procedure is based on a discrete analogon of Green's theorem and is much faster than the method introduced earlier by Zakaria et al. The new scheme produces exact results, unlike methods based on the continuous Green's theorem.
The two-dimensional scalar problem of an inhomogeneous, thin, circular, dielectric cylindrical shell exposed to a transverse magnetic (TM) incident field is considered. An algorithm based on the fast Fourier transform...
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The two-dimensional scalar problem of an inhomogeneous, thin, circular, dielectric cylindrical shell exposed to a transverse magnetic (TM) incident field is considered. An algorithm based on the fast Fourier transform is proposed to implement the integral-equation method efficiently. Details of computer simulations are provided, illustrating the validity of the method proposed.
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