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Robust incident-angle field estimation:a one-way wave propagator approach

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Robust incident-angle field estimation:a one-way wave propag...

Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation

中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Jiangjie Zhang Hui Zhang Institute of Geology and Geophysics Key Laboratory of Petroleum Resources ResearchChinese Academy of Sciences

The incident angle is a very important piece of information in many processing steps for seismic data,but it cannot be easily and directly estimated in many typical and familiar migration processes,such as shot-profile wave equation migration and reverse time *** this paper,we first revisit and analyse some popular schemes of estimating the incident-angle *** we present a robust method to estimate the incident-angle field in a 2D/3D heterogeneous isotropic media based on a one-way wave *** the band-limited wavefield,the incident-angle field is estimated by the division of two impulse responses of the monochromatic wavefield in order to reduce *** impulse responses are the derivative of the angle-weighted image extracted by multiplying an extra imaging weight in the conventional migration process and conventional *** tilted coordinate system is adopted in our method to avoid the steep-angle limitation of one-way wave *** comparison with other methods,our method can estimate the incident-angle field more accurately with higher efficiency and less memory *** incident-angle fields of a 2D layered model and 3D field data example demonstrate the generality and flexibility of the method.

关键词： incident angle one-way wave extrapolation ray tracing seismic wave propagation

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Chinese Physics B 2024年第5期33卷 489-499页

作者：吴翔张珈珲董果香石磊 School of Aerospace Science and Technology Xidian UniversityXi'an 710071China

“Magnetic window”is considered as an effective method to solve the communication blackout *** software package based on the finite element method is utilized to simulate the propagation of right-handed circularly polarized wave in the magnetized plasma *** assume a double Gaussian model of electron density and an exponential attenuation model of magnetic *** propagation characteristics of right-handed circularly polarized wave are analyzed by the observation of the reflected,transmitted and loss *** numerical results show that the propagation of right-handed circularly polarized wave in the magnetized plasma sheath varies for different incident angles,collision frequencies,non-uniform magnetic fields and non-uniform plasma *** notice that reducing the wave frequency can meet the propagation conditions of whistle mode in the weak magnetized plasma *** the transmittance of whistle mode is less affected by the variation of the electron density and the collision *** can be used as a communication window.

关键词： magnetized plasma sheath communication blackout finite element incident angle whistler wave

A Lamb wave quantification model for inclined cracks with experimental validation

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Chinese Journal of Aeronautics 2021年第2期34卷 601-611页

作者： Jingjing HE Haode HUO Xuefei GUAN Jinsong YANG School of Reliability and Systems Engineering Beihang UniversityBeijing 100083China Graduate School of China Academy of Engineering Physics Beijing 100193China CAD/CAM Institute Central South UniversityChangsha 410083China

This paper investigates the influence of crack orientation on damage quantification using Lamb wave in plate structures. Finite element simulation is performed to acquire Lamb wave signal responses for different configurations of crack orientations and crack lengths. Two Lamb wave features, namely the normalized amplitude and the phase change, are used as damage sensitive features to develop a crack size quantification model. A hypothesis based on the geometrical influence on signal features is proposed, and the crack size quantification model incorporating the orientation angle is established using the hypothesis. An index of Probability of Reliable Quantification(PRQ) is proposed to evaluate the performance of the model. The index can be used to determine the sizing risk in terms of probabilities. A realistic aluminum plate is used to obtain the experimental data using piezoelectric(PZT) wafer-type sensors around a center through crack. The experimental data are used to validate the overall method. Results indicate that the proposed model can yield reliable results for size quantification of inclined cracks.

关键词： Crack orientation Crack size quantification model incident angle Lamb wave Probability of reliable quantification(PRQ)

Nanosecond laser-induced controllable periodical surface structures on silicon

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Chinese Optics Letters 2022年第1期20卷 186-191页

作者： Lei Chen Zelin Liu Chuan Guo Tongcheng Yu Minsun Chen Zhongjie Xu Hao Liu Guomin Zhao Kai Han College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China Hunan Provincial Key Laboratory of High Energy Laser Technology Changsha 410073China State Key Laboratory of Pulsed Power Laser Technology Hefei 230037China

In this paper,an effective method is proposed to generate specific periodical surface structures.A 532 nm linearly polarized laser is used to irradiate the silicon with pulse duration of 10 ns and repetition frequency of 10 ***-induced periodic surface structures(LIPSSs) are observed when the fluence is 121 mJ/cm;and the number of pulses is *** threshold of fluence for generating LIPSS gradually increases with the decrease of the number of *** addition,the laser incident angle has a notable effect on the period of LIPSS,which varies from 430 nm to 1578 nm,as the incident angle ranges from10° to 60° ***,the reflectivity is reduced significantly on silicon with LIPSS.

关键词： laser-induced periodic surface structure nanostructures fluence number of pulses incident angle