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mode separation of resonant cavity by electromagnetic simulation

Journal of Harbin Institute of Technology(New Series) 2001年第1期8卷 27-29页

作者：吴群 Institute of Aerospace Harbin Institute of Technology Seoul National University

Presents the investigation of characteristics of mode separation in typical magnetron cavity for the great importance of precise prediction of mode separation used in the theoretical study and engineering design of magnetrons, and the comparative theoretical predication and simulation analysis made using field theory and computer simulation based on commercial EDA tools, Ansoft High Frequency Structure Simulator(HFSS)and POISSON SUPERFISH.

关键词： resonant cavity mode separation simulation

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ELASTIC WAVE-mode separation BY PREDEFORMED HYPERELASTIC MATERIALS

ELASTIC WAVE-MODE SEPARATION BY PREDEFORMED HYPERELASTIC MAT...

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2016年全国压电和声波理论及器件应用研讨会

作者： Lin-li CHEN Zheng CHANG College of Science China Agricultural University

Background, Motivation and Objective Longitudinal and shear waves are two main wave-modes of elastic body waves. Spatially, they often entangled with each other and are difficult to be separated apart. In this work, we show these two wave-modes manifest distinct characteristics and propagate in different paths in deformed hyperelastic materials. This enables us to physically disentangle the two wave-modes and design an elastic wave-mode splitter. The effect of material constitutive relations, material parameters and loading conditions on the performance of wave-mode splitter are systematically investigated. Statement of Contribution/Methods In the framework of Small-on-Large theory, the characteristic equation of the elastic wave propagation inhomogeneously pre-deformed hyperelastic materials can be analytically expressed. The slowness of the longitudinal and shear elastic waves can then be derived through an eigenvalue approach, and the wave paths refracted from an interface between an un-deformed and a deformed hyperelastic material can be determined from the phase-slowness curves. As it can be theoretically shown the two elastic wave modes manifest different refraction angles in pre-deformed hyperelastic material, a prototype of elastic wave-mode splitter can be proposed: With a homogeneous simple shear deformation field applied on a cuboid hyperelastic solid, the entangled elastic waves are imported from one lateral side of the hyperelastic solid and the separated pure waves can be received on the other side. The performance of the wave-mode splitter can be determined by the angle between the longitudinal and shear elastic waves in the hyperelastic solid. By considering three typical hyperelastic materials, Neo-Hookean material, Gent material and Arruda-Boyce material, we theoretically and numerically investigate the performance of the wave-mode splitters with different conditions. The theoretical method is based on the above mentioned phase-slowness curve appro

关键词： Elastic wave mode separation Small-on-Large Hyperelastic

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Non-contact air-coupled transducers Lamb wave signal multipath effect and blind separation for different modes using PZT as receiver

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Chinese Journal of Aeronautics 2024年第10期37卷 424-434页

作者： Desheng WU Zhibo YANG Yu RUAN Wenbo LI Lijuan YANG Xuefeng CHEN National Key Lab of Aerospace Power System and Plasma Technology Xi’an Jiaotong UniversityXi’an 710049China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China

Due to the complexity and faintness of the detection wave patterns obtained by aircoupled transducers,if it is possible to effectively separate the various modes and obtain nondispersive signals for more accurate detection and positioning,it will help to improve the accuracy and reliability of air-coupled ultrasonic Lamb wave detection,providing better technical support for the application and development of related *** of the increased complexity of aircoupled signals,there is no definite theoretical formula to describe the mode changes of aircoupled signals,so the method based on blind separation has unique *** address these challenges,the paper proposes a single-channel blind source separation(SCBSS)*** effectiveness of this method is evaluated through simulations and experiments,demonstrating favorable separation results and efficient computational *** work first conducts an in-depth analysis of the signal characteristics of air-coupled ultrasonic non-destructive testing,and simulates the ultrasonic excitation conditions of air-coupled sensors through finite element *** study of modal changes and multipath effects caused by the variation of the incidence angle of the ACT signal is carried out,and the situation of the Lamb wave signal excited by ACT at the receiving end is *** combining ACT with PZT signals,the ultrasonic signals of air-coupled Lamb waves are compared and studied,and their modal purification is carried out.

关键词： Air-coupled transducers Lamb wave mode separation Blind source separation Non-destructive testing

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High-Frequency Rayleigh-Wave Method

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Journal of China University of Geosciences 2009年第3期20卷 563-579页

作者： Richard D Miller 徐义贤罗银河陈超刘江平 Julian Ivanov Kansas Geological Survey The University of KansasLawrence KS 66047 USA Institute of Geophysics and Geomatics China University of Geosciences Kansas Geological Survey The University of Kansas

High-frequency （〉2 Hz） Rayleigh-wave data acquired with a multichannel recording system have been utilized to determine shear （S）-wave velocities in near-surface geophysics since the early 1980s. This overview article discusses the main research results of high-frequency surface-wave techniques achieved by research groups at the Kansas Geological Survey and China University of Geosciences in the last 15 years. The multichannel analysis of surface wave （MASW） method is a non-invasive acoustic approach to estimate near-surface S-wave velocity. The differences between MASW results and direct borehole measurements are approximately 15% or less and random. Studies show that simultaneous inversion with higher modes and the fundamental mode can increase model resolution and an investigation depth. The other important seismic property, quality factor （Q）, can also be estimated with the MASW method by inverting attenuation coefficients of Rayleigh waves. An inverted model （S-wave velocity or Q） obtained using a damped least-squares method can be assessed by an optimal damping vector in a vicinity of the inverted model determined by an objective function, which is the trace of a weighted sum of model-resolution and model-covariance matrices. Current developments include modeUng high-frequency Rayleigh-waves in near-surface media, which builds a foundation for shallow seismic or Rayleigh-wave inversion in the time-offset domain; imaging dispersive energy with high resolution in the frequency-velocity domain and possibly with data in an arbitrary acquisition geometry, which opens a door for 3D surface-wave techniques; and successfully separating surface-wave modes, which provides a valuable tool to perform S-wave velocity profiling with high-horizontal resolution.

关键词： Rayleigh wave dispersion high mode mode separation seismic modeling model appraisal.

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