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A Three-Point Method for Separating Incident and reflected waves over A Sloping Bed

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China Ocean Engineering 2002年第4期17卷 499-511页

作者： CHANG Hsien-Kuo Department of Civil Engineering National Chiao Tung UniversityHsinchu 300China

This study presents a three-point method for separating incident and reflected waves to explain normally incident waves' propagating over a sloping bed. linear wave shoaling is used to determine changes in wave amplitude and phase in response to variations of bathymetry. The wave reflection coefficient and incident amplitude are estimated from wave heights measured at three fixed wave gauges with unequal spacing. Sensitivity analysis demonstrates that the proposed method can predict the reflection and amplitude of waves over a sloping bed more accurately than the two-point method.

关键词： reflected wave wave shoaling sloping bed

Crack dynamic propagation properties and arrest mechanism under impact loading

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1171-1184页

作者： Yuqing Dong Zheming Zhu Li Ren Lei Zhou Peng Ying Meng Wang State Key Laboratory of Hydraulics and Mountain River Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science and Engineering School of Architecture and EnvironmentSichuan UniversityChengdu610065China

Crack dynamic propagation and arrest behaviors have received extensive attention over the ***,there still remain many questions,*** what conditions will a running crack come to arrest?In this paper,drop weight impact(DWI)tests were conducted to investigate crack arrest mechanism using single cleavage triangle(SCT)rock *** sandstone was selected to prepare the SCT *** stress intensity factors(DSIFs)were calculated by ABAQUS code,and the critical DSIFs were determined by crack propagation speeds and fracture time measured by crack propagation gauges(CPGs).The test results show that the critical DSIF at propagation decreases with crack propagation *** simulation for SCT specimens under different loading waves was performed using AUTODYN *** reflected compressive wave from the incident and transmitted plates can induce crack arrests during propagation,and the number of arrest times increases with the wave *** order to eliminate the effect of the incident and transmitted plates,models consisting of only one SCT specimen without incident and transmitted plates were established,and the same trapezoid-shaped loading wave was applied to the SCT *** results show that for the SCT specimen with transmitted boundary(analogous to an infinite plate),the trapezoid-shaped loading wave cannot induce crack arrest *** numerical results can well describe the occurrence of crack arrest in the experiments.

关键词： Crack arrest Stress wave Fracture toughness reflected wave Impact loading

Reflection of Short waves

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China Ocean Engineering 1999年第1期14卷 31-46页

作者： Miguel A. LOSADA University of Cantabria

According to the; energy equation, the relation between reflection and energy losses for short waves from mild beaches is established and analysed. A reflection coefficient varying with position and energy losses is proposed. Different reflection tests are conducted to check the theoretical analysis. A modified method to estimate the reflection coefficient at varied water depths is suggested based on the linear wave theory. The study indicates that the reflection coefficient from mild beaches has a changing trend for short waves approaching shoreline.

关键词： reflection incident wave reflected wave short wave

wave reflection, transmission and harmonics due to different submerged structures

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Acta Oceanologica Sinica 2000年第2期19卷 111-125页

作者： Gao Xueping1 Inouchi Kunimitsu2 Kakinuma Tadao3 (1. Hydraulics Institute, Faculty of Civil Engineering, Tianjin University, Tianjin 300072, China 2. Center for Cooperative Research and Development, Ehime University, 3 Bunkyo-cho, Matsuyama 790 - 8577, Japan 3. Nagasaki Comprehensive University, Aba-cho 536, Nagasaki 851 - 0193, Japan) Hydraulics Institute Faculty of Civil Engineering Tianjin University Tianjin 300072 China

Comparisons of wave reflection, transmission and harmonics due to different types of sub merged structures are investigated by a numerical method, the boundary-fitted coordinate (BFC) method. The types of submerged structures include a submerged horizontal plate, submerged breakwa ters (rectangular and trapezoidal) and a step-type structure (topography). First, the BFC method is ver ified by comparing the computed results with the experimental data, including wave surface elevations, reflected and transmitted wave heights, and amplitudes of higher harmonics, showing that the method is a reasonable one to predict wave deformations due to the submerged structures. Secondly, the wave sur face elevations and the higher harmonics over different submerged structures are compared. Thirdly, re flected and transmitted waves due to different submerged structures are investigated.

关键词： Harmonic wave reflected wave transmitted wave submerged structure boundary-fitted coordinate method

Theoretical Calculation of Floating Breakwater Performance

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China Ocean Engineering 1992年第4期7卷 415-424页

作者： Lao Guosheng Feng Hong Associate Professor, Dalian University of Technology, 116024, Dalian Postgraduate, Dalian University of Technology, 116024, Dalian

In this paper, the theoretical calculation of floating breakwater performance in regular waves with arbitrary wave direction is discussed. Under the hypothesis of linearized system and applying the strip theory, we can solve the boundary condition problems of diffraction potential and radiation potential. Introducing the asymptotic expression of the wave velocity potential at infinity and using wave energy conservation, we can separately calculate the transmitted waves generated by the sway, heave and roll motion of the floating breakwater and by the fixed breakwater. Finally, we define the amplitude ratio of the transmitted wave to the incident wave as the transmitted wave coefficient CT which describes the floating breakwater effectiveness. Two examples are given and the theoretical results obtained by the present method agree well with experimental results.

关键词： floating breakwater fixed breakwater transmitted wave reflected wave incident wave

Application of multi-channel two-dimensional transient Rayleigh wave exploration in goaf detection

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Global Geology 2010年第1期13卷 56-60页

作者： DU Lizhi ZHANG Xiaopei WANG Yong College of Construction Engineering Jilin University Changchun 130026 China

The transient Rayleigh wave exploration has high detection accuracy in shallow exploration. The effect of detection array is comprehensive reflection of the velocity of rock and soil mass. Therefore, the roiling multi-channel transient acquisition system has been adopted in this study, which turns one dimensional transient Rayleigh wave exploration into two dimensions, consequently, the two-dimensional velocity distribution of rock and soil mass under the survey line has been achieved. Through comparing with the shallow seismic reflected wave exploration, the result indicates that the rolling multi-channel transient acquisition system has accurate resolution. Thus, in the process of the shallow reflected wave exploration, if the surface wave has developed, the coalition between the reflected wave exploration and the two-dimensional transient Rayleigh wave exploration should actualize the accuracy of exploration.

关键词： Rayleigh wave two-dimensional transient muhi-channel reflected wave shear wave

The interference characteristics of platform and towed body noise in shallow water for active/passive towed array sonar

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Chinese Journal of Acoustics 2007年第3期26卷 193-197页

作者： LI Qihu LI Shuqiu SUN Changyu YU Huabing Institute of Acoustics The Chinese Academy of Sciences Beijing 100080

The interference characteristics of towed platform noise resulted from propeller and towed body for active/passive towed array is analyzed. It is shown that, in shallow water environment, the direct wave and bottom/sea surface reflected wave will seriously affect the performance of sonar system. The formula for calculating the direction of arrival （DOA） of interference in terms of various parameters, such as array depth, length of tow cable, is derived. The effect of interference noise for the detection performance of sonar system is described. The results of system simulation provide the method for reducing the effect of these kind of interferences.

关键词： detection performance interference noise water environment system simulation reflected wave

A SPATIAL IMPULSE RESPONSE BASED MODEL FOR THE ACOUSTIC FIELD IN DETECTION OF BURIED OBJECTS WITH LOW FREQUENCY waveS

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A SPATIAL IMPULSE RESPONSE BASED MODEL FOR THE ACOUSTIC FIEL...

waveform migration of scattering seismic data

第三届全国压电和声波理论及器件技术研讨会

作者： Hui-feng XU,Yan-ling QIAN College of Mechatronics Engineering and Automation,National University of Defense Technology,Changsha 410073,China

A number of mathematical models have been developed and used for received signal processing in acoustic detection of buried objects with low frequency waves up to *** of them are linear combination of signals and impulses of the *** are too simple to make in-depth analysis of the parameters of the ***,a spatial impulse response based model is proposed for the acoustic detection system,which is derived from the basic theory of sound propagation and geometrical relation of the *** the physical meaning of the model is *** this way,the model can be applied to predict and determine the parameters of the detection system,and it is the basic theory in signal processing of the *** simulated results and the measured received signals are compared,and it is shown that the simulated and measured results are in good agreement.

关键词： Spatial impulse response acoustic detection direct wave reflected wave

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Waveform migration of scattering seismic data