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phase spectrum based automatic ship detection in synthetic aperture radar images

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Journal of Ocean Engineering and Science 2021年第2期6卷 185-195页

作者： Miaohui Zhang Baojun Qiao Ming Xin Bo Zhang Henan Key Laboratory of Big Data Analysis and Processing Henan UniversityKaifengChina Institute of Data and Knowledge Engineering Henan UniversityKaifengChina School of Computer Science and Engineering Beihang UniversityBeijingChina

This paper proposes an automatic ship detection approach in Synthetic Aperture Radar(SAR)Images using phase *** proposed method mainly contains two stages:Firstly,sea-land segmentation of SAR Images is one of the key stages for SAR image application such as sea-targets detection and recognition,which are easily detected only in sea *** order to eliminate the influence of land regions in SAR images,a novel land removing method is *** removing method employs a Harris corner detector to obtain some image patches belonging to land,and the probability density function(PDF)of land area can be estimated by these ***,an appropriate land segmentation threshold is accordingly ***,an automatic ship detector based on phase spectrum is *** proposed detector is free from various idealized assumptions and can accurately detect ships in SAR *** results demonstrate the efficiency of the proposed ship detection algorithm in diversified SAR images.

关键词： Ship detection saliency detection phase spectrum sea-land segmentation

The application of ultrasonic phase spectrum of the reflection coefficient on nondestructive characterizing the plasma sprayed coatings irradiated by HIPIB

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The application of ultrasonic phase spectrum of the reflecti...

Dispersion Analysis and Compensation of Collinear Optical Parametric Chirped Pulse Amplification Systems

Fifth International Conference on Surface Engineering

作者： Y.ZHAO1,L.LIN1,X.M.LI1,M.K.LEI1 1 NDT & E Laboratory,School of Materials Science & Engineering,Dalian University of Technology,Dalian 116024,P.R.China 2 Surface Engineering Laboratory,School of Materials Science & Engineering,Dalian University of Technology,Dalian 116024,P.R.China

Ultrasonic phase spectrum of reflection coefficient has been used to nondestructively characterize the density,porosity,and microcracks of plasma sprayed Cr2O3 coatings irradiated by high-intensity pulsed ion beam(HIPIB).The ultrasonic measurement was investigated using immersion focusing pulse echo method with a 25 MHz transducer and the phase spectrum of reflection coefficient has been experimentally *** relationship among velocity,density,attenuation coefficient and the phase spectrum was analyzed based on an acoustic transmission model in a multi-layered *** velocity relates to the harmonic frequency of the phase spectrum,and the density and attenuation coefficient play roles on the amplitude of the maximum and the shape of the *** effects of the three parameters(velocity,density and attenuation coefficient) on the amplitude of the maximum of the phase are *** critical value exists which change the relationship between the individual parameter and the *** one of the three parameters exceeds the corresponded critical value,the amplitude of the maximum decreases in the same form of y=Aexp(Bxn).For the as-sprayed and irradiated coatings with the thickness of 50 μm,the velocity calculated from the phase spectrum is 2522 m/s and 2772 m/s,harmonic frequency corresponding to 12.61 MHz and 13.86 MHz,*** ultrasonic determinations demonstrated that the coating became more densified after irradiation by HIPIB,which are in agreement with SEM *** phase spectrum itself is a good indicator to reveal differences between density and microstructures of coating prepared with various conditions as well as to follow their evolution after HIPIB *** method developed has found application in the problem of characterizing the coatings.

关键词： Ultrasonic Characterization Reflection Coefficient phase spectrum Cr2O3 Coatings Density

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Chinese Physics Letters 2005年第12期22卷 3091-3093页

作者：王乘冷雨欣梁晓燕张春梅赵保真徐至展 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800

In an optical parametric chirped pulse amplification （OPCPA） laser system, residual phase dispersion should be compensated as much as possible to shorten the amplified pulses and improve the pulse contrast ratio. Expressions of orders of the induced phases in collinear optical parametric amplification （OPA） processes are presented at the central signal wavelength to depict a c/ear physics picture and to simplify the design of phase compensation. As examples, we simulate two OPCPA systems to compensate for the phases up to the partial fourth-order terms, and obtain flat phase spectra of 200-nm bandwidth at 1064nm and 90-nm at 800nm.

关键词： phase compensation compensated Dispersion dispersion phase spectrum phase DISPERSION Collinear Parametric optical Chirped Pulse Amplification OPCPA phase

Seismic Attribute Analysis with Saliency Detection in Fractional Fourier Transform Domain

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Journal of Earth Science 2018年第6期29卷 1372-1379页

作者： Yuqing Wang Zhenming Peng Yan Han Yanmin He School of Optoelectronic Information University of Electronic Science and Technology of China Center for Information Geoscience University of Electronic Science and Technology of China

Most image saliency detection models are dependent on prior knowledge and demand high computational cost. However, spectral residual（SR） and phase spectrum of the Fourier transform（PFT） models are simple and fast saliency detection approaches based on two-dimensional Fourier transform without the prior knowledge. For seismic data, the geological structure of the underground rock formation changes more obviously in the time direction. Therefore, one-dimensional Fourier transform is more suitable for seismic saliency detection. Fractional Fourier transform（FrFT） is an improved algorithm for Fourier transform, therefore we propose the seismic SR and PFT models in one-dimensional FrF T domain to obtain more detailed saliency maps. These two models use the amplitude and phase information in FrFT domain to construct the corresponding saliency maps in spatial domain. By means of these two models, several saliency maps at different fractional orders can be obtained for seismic attribute analysis. These saliency maps can characterize the detailed features and highlight the object areas, which is more conducive to determine the location of reservoirs. The performance of the proposed method is assessed on both simulated and real seismic data. The results indicate that our method is effective and convenient for seismic attribute extraction with good noise immunity.

关键词： saliency detection spectral residual phase spectrum fractional Fourier transform (FrFT) attribute extraction seismic data

Key Frame Extraction of Surveillance Video Based on Fractional Fourier Transform

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Journal of Beijing Institute of Technology 2021年第3期30卷 311-321页

作者： Yunzuo Zhang Jiayu Zhang Ran Tao the School of Information Science and Technology Shijiazhuang Tiedao University the School of Information and Electronics Beijing Institute of Technology

With the vigorous development of national infrastructure construction and public information construction, video surveillance systems have gradually penetrated various fields. The current key frame extraction technology has inadequate target details and inaccurate judgment of local actions. Addressing this problem, a key frame extraction method based on fractional Fourier transform is proposed. This method obtained the phase spectra information of different orders by performing fractional Fourier transform on the surveillance video frames. Next, the method designed an adaptive algorithm based on the golden section point to select the transformation ***, the phase spectrum information of two adjacent frames was used to characterize the changes in the global and local motion states of the target. The final step was to extract key frames based on this. Experimental results show that, compared with the previous methods, the key frames extracted by the method proposed in this paper can correctly capture the changes in the global and local motion states of the target.

关键词： fractional Fourier transform (FRFT) phase spectrum key frame extraction adaptation local motion status

The statistical laws of strong seismic motion phase characteristics

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Acta Seismologica Sinica(English Edition) 1994年第1期7卷 141-147页

作者：金星廖振鹏 Institute of Engineering Mechanics State Seismological Bureau Harbin China

Under the assumption of an effective point source model,this paper introduces a conception of equivalent phase velocity to describle the average propagation processes and dispersion properties of seismic waves from seismic source to the site,then illuminates the relation between the phase properties of seismic motion and equivalent phase velocity and obtains a simple formula of estimating the equivalent phase velocity through the use of the phase difference spectrum of seismic *** the parts of strong seismic records in the western American and the SMART-1 array are used to identify the method presented by this paper in reason,the statistical relations of equivalent phase velocity are given in the above two *** results of the paper have demonstrated that the phase spectrum of seismic motion has its inner law as same as the amplitude spectrum does.

关键词： equivalent phase velocity relative phase velocity phase spectrum relative group velocity phase difference spectrum

STUDY ON phase PERCEPTION IN SPEECH

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Journal of Electronics(China) 2003年第5期20卷 387-392页

作者： TongMing BianZhengzhong LiXiaohui DaiQijun ChenYanpu Xi‘anJiaotongUniversity Xi’an710049 XidianUniversity Xi‘’an710049 Xi‘anCommunicationCollege Xi’an710106

The perceptual effect of the phase information in speech has been studied by auditorysubjective tests. On the condition that the phase spectrum in speech is changed while amplitudespectrum is unchanged, the tests show that: (1) If the envelop of the reconstructed speech signalis unchanged, there is indistinctive auditory perception between the original speech and thereconstructed speech; (2) The auditory perception effect of the reconstructed speech mainly lieson the amplitude of the derivative of the additive phase; (3) td is the maximum relative time shiftbetween different frequency components of the reconstructed speech signal. The speech qualityis excellent while td ＜10ms; good while 10ms＜ td ＜20ms; common while 20ms＜ td ＜35ms, andpoor while td ＞35ms.

关键词： Speech signal Auditory perception phase spectrum Additive phase

Stochastic modeling for starting-time of phase evolution of random seismic ground motions

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Theoretical & Applied Mechanics Letters 2014年第1期4卷 63-67页

作者： Yongbo Peng Jie Li State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai Institute of Disaster Prevention and Relief Tongji University School of Civil Engineering Tongji University

In response to the challenge inherent in classical high-dimensional models of random ground motions, a family of simulation methods for nonstationary seismic ground motions was developed previously through employing a wave-group propagation formulation with phase spectrum model built up on the frequency components’ starting-time of phase evolution. The present paper aims at extending the formulation to the simulation of non-stationary random seismic ground motions. The ground motion records associated with N–S component of Northridge Earthquake at the type-II site are investigated. The frequency components’ starting-time of phase evolution of is identified from the ground motion records, and is proved to admit the Gamma distribution through data fitting. Numerical results indicate that the simulated random ground motion features zeromean, non-stationary, and non-Gaussian behaviors, and the phase spectrum model with only a few starting-times of phase evolution could come up with a sound contribution to the simulation.

关键词： stochastic modeling starting-time phase spectrum Gamma distribution nonstationary Northridge Earthquake

Determination of the surface wave dispersion of a coating excited by laser

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Determination of the surface wave dispersion of a coating ex...