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  • Open Access


    Transmission and Reflection of Water-Wave on a Floating Ship in Vast Oceans

    Amel A. Alaidrous*

    CMC-Computers, Materials & Continua, Vol.67, No.3, pp. 2971-2988, 2021, DOI:10.32604/cmc.2021.015159

    Abstract In this paper, we study the water-wave flow under a floating body of an incident wave in a fluid. This model simulates the phenomenon of waves abording a floating ship in a vast ocean. The same model, also simulates the phenomenon of fluid-structure interaction of a large ice sheet in waves. According to this method. We divide the region of the problem into three subregions. Solutions, satisfying the equation in the fluid mass and a part of the boundary conditions in each subregion, are given. We obtain such solutions as infinite series including unknown coefficients.… More >

  • Open Access


    Windowing Techniques, the Welch Method for Improvement of Power Spectrum Estimation

    Dah-Jing Jwo1,*, Wei-Yeh Chang1, I-Hua Wu2

    CMC-Computers, Materials & Continua, Vol.67, No.3, pp. 3983-4003, 2021, DOI:10.32604/cmc.2021.014752

    Abstract This paper revisits the characteristics of windowing techniques with various window functions involved, and successively investigates spectral leakage mitigation utilizing the Welch method. The discrete Fourier transform (DFT) is ubiquitous in digital signal processing (DSP) for the spectrum analysis and can be efficiently realized by the fast Fourier transform (FFT). The sampling signal will result in distortion and thus may cause unpredictable spectral leakage in discrete spectrum when the DFT is employed. Windowing is implemented by multiplying the input signal with a window function and windowing amplitude modulates the input signal so that the spectral… More >

  • Open Access


    New SAR Imaging Algorithm via the Optimal Time-Frequency Transform Domain

    Zhenli Wang1, *, Qun Wang1, Jiayin Liu1, Zheng Liang1, Jingsong Xu2

    CMC-Computers, Materials & Continua, Vol.65, No.3, pp. 2351-2363, 2020, DOI:10.32604/cmc.2020.011909

    Abstract To address the low-resolution imaging problem in relation to traditional Range Doppler (RD) algorithm, this paper intends to propose a new algorithm based on Fractional Fourier Transform (FrFT), which proves highly advantageous in the acquisition of high-resolution Synthetic Aperture Radar (SAR) images. The expression of the optimal order of SAR range signals using FrFT is deduced in detail, and the corresponding expression of the azimuth signal is also given. Theoretical analysis shows that, the optimal order in range (azimuth) direction, which turns out to be very unique, depends on the known imaging parameters of SAR, More >

  • Open Access


    High Resolution SAR Image Algorithm with Sample Length Constraints for the Range Direction

    Zhenli Wang1, *, Qun Wang1, Fujuan Li1, Shuai Wang2

    CMC-Computers, Materials & Continua, Vol.63, No.3, pp. 1533-1543, 2020, DOI:10.32604/cmc.2020.09721

    Abstract The traditional Range Doppler (RD) algorithm is unable to meet practical needs owing to the limit of resolution. The order of fractional Fourier Transform (FrFT) and the length of sampling signals affect SAR imaging performance when FrFT is applied to RD algorithm. To overcome the above shortcomings, the purpose of this paper is to propose a high-resolution SAR image algorithm by using the optimal order of FrFT and the sample length constraints for the range direction. The expression of the optimal order of SAR range signals via FrFT is deduced in detail. The initial sample More >

  • Open Access


    Analysis and Process of Music Signals to Generate TwoDimensional Tabular Data and a New Music

    Oakyoung Han1, Jaehyoun Kim2, *

    CMC-Computers, Materials & Continua, Vol.63, No.2, pp. 553-566, 2020, DOI:10.32604/cmc.2020.09362

    Abstract The processing of sound signals is significantly improved recently. Technique for sound signal processing focusing on music beyond speech area is getting attention due to the development of deep learning techniques. This study is for analysis and process of music signals to generate tow-dimensional tabular data and a new music. For analysis and process part, we represented normalized waveforms for each of input data via frequency domain signals. Then we looked into shorted segment to see the difference wave pattern for different singers. Fourier transform is applied to get spectrogram of the music signals. Filterbank… More >

  • Open Access


    A Joint Delay-and-Sum and Fourier Beamforming Method for High Frame Rate Ultrasound Imaging

    Wei Zhao1, 2, Shuai Feng1, Yadan Wang1, Yuanguo Wang1, Zhihui Han1, Hu Peng1, *

    CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.1, pp. 427-440, 2020, DOI:10.32604/cmes.2020.09387

    Abstract Frame rate is an important metric for ultrasound imaging systems, and high frame rates (HFR) benefit moving-target imaging. One common way to obtain HFR imaging is to transmit a plane wave. Delay-and-sum (DAS) beamformer is a conventional beamforming algorithm, which is simple and has been widely implemented in clinical application. Fourier beamforming is an alternative method for HFR imaging and has high levels of imaging efficiency, imaging speed, and good temporal dynamic characteristics. Nevertheless, the resolution and contrast performance of HFR imaging based on DAS or Fourier beamforming are insufficient due to the single plane… More >

  • Open Access


    Two-Dimensional Interpolation Criterion Using DFT Coefficients

    Yuan Chen1, Liangtao Duan1, Weize Sun2, *, Jingxin Xu3

    CMC-Computers, Materials & Continua, Vol.62, No.2, pp. 849-859, 2020, DOI:10.32604/cmc.2020.07115

    Abstract In this paper, we address the frequency estimator for 2-dimensional (2-D) complex sinusoids in the presence of white Gaussian noise. With the use of the sinc function model of the discrete Fourier transform (DFT) coefficients on the input data, a fast and accurate frequency estimator is devised, where only the DFT coefficient with the highest magnitude and its four neighbors are required. Variance analysis is also included to investigate the accuracy of the proposed algorithm. Simulation results are conducted to demonstrate the superiority of the developed scheme, in terms of the estimation performance and computational More >

  • Open Access


    Vibration Fatigue Analysis of Cylinder Head of a New Two-Stroke Free Poston Engine Using Finite Element Approach

    M. M. Rahman1, A. K. Ariffin1, N. Jamaludin1, C. H. C. Haron1

    Structural Durability & Health Monitoring, Vol.1, No.2, pp. 121-130, 2005, DOI:10.3970/sdhm.2005.001.121

    Abstract The focus of this paper is to design a new two-stroke linear generator engine. This paper describes the finite element based vibration fatigue analysis techniques that can be used to predict fatigue life using total life approach. Fatigue damage in traditionally determined from time signals of loading, usually in the form of stress and strain. However, there are scenarios when a spectral form of loading is more appropriate. In this case the loading is defined in terms of its magnitude at different frequencies in the form of a power spectral density (PSD) plot. A power… More >

  • Open Access


    Dynamic Analyses of a Simply Supported Double-Beam System Subject to a Moving Mass with Fourier Transform Technique

    Lizhong Jiang1,2, Xilin Chai1,2, Zhihua Tan1,2, Wangbao Zhou1,2,*, Yulin Feng1,2, Zhipeng Lai1,2, Lan Zheng1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.1, pp. 291-314, 2019, DOI:10.32604/cmes.2019.07805

    Abstract In order to study the dynamic characteristics of a simply supported double-beam system under a moving mass, the system of fourth-order dynamic partial differential equations of a simply supported double-beam system was transformed into a system of second-order dynamic ordinary differential equations relative to time coordinates by performing the finite sin-Fourier Transform relative to space coordinates. And the analytical solution of the dynamic response of the simply supported double-beam system under a moving mass was obtained by solving the system of dynamic ordinary differential equations. The analytical method and ANSYS numerical method were used to… More >

  • Open Access


    The spatial laser interferometry with combination of fast Fourier transformation technique applied to measuring micro object 3D profile

    Xianfu Huang, Zhanwei Liu, Jianxin Gao, Huimin Xie

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.1, pp. 25-26, 2011, DOI:10.3970/icces.2011.017.025

    Abstract The spatial laser interferometry with combination of fast Fourier transformation (FFT) technique has been applied to analyze and reshape 3D profile of micro objects in this paper. In this technique, two beam of coherent spatial laser would superpose and interfere with each other to produce fringes with constant pitches. Deformed fringe lines would be generated on a tested object surface for its 3D height existence when a micro-movable platform with the tested object on it is placed in the spatial interferential fringe field. On the analysis of the fringe pattern collected by CCD which carries… More >

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