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Highly efficient conversion from classical guided waves to topological chiral edge states

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Chinese Optics Letters 2024年第2期22卷 221-226页

作者：韩建飞梁锋赵玉林丁霄汪相如赵德双王秉中 School of Physics University of Electronic Science and Technology of ChinaChengdu 611731China School of Optoelectronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and ***,the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world *** this paper,a highly efficient conversion structure between a classical rectangular waveguide and a topological one-way waveguide is proposed and demonstrated at the microwave frequency,which efficiently converts classical guided waves to topological one-way edge states.A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge *** the conversion structure,the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling efficiency,which can ensure high transmission of the whole system(i.e.,from the source and the receiver).Simulation and measurement results demonstrate the proposed *** investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems.

关键词： guided waves highly efficient conversion photonic crystals topological chiral edge states

The Inspection of Level Crossing Rails Using guided waves

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Journal of Traffic and Transportation Engineering 2023年第1期11卷 29-35页

作者： Mark Evans guided Ultrasonic Ltd Brentford TW88HQUK

Level crossing rails are high risk areas due to the combination of the limited effectiveness of current inspection methods and high corrosion rates which often *** paper discusses the current UK standard practices for the periodic inspection of level crossing rails using visual(VT)and conventional ultrasonic(UT)*** limitations of these methods are discussed and how these limitations affect the overall maintenance program for level crossings.A new inspection method,guided wave testing(GWT)is then described with particular emphasis on its advantages for inspecting level ***,a review is given of the current Network Rail trial of GWT on level crossings using the G-Scan system,with representative results which demonstrate the effectiveness of GWT for this application.

关键词： Rails guided waves GWT

APPLICATIONS OF ULTRASONIC guided waves IN NON-DESTRUCTIVE TESTING OF LARGE STRUTURES

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APPLICATIONS OF ULTRASONIC GUIDED WAVES IN NON-DESTRUCTIVE T...

THE INVERSE OF MATERIAL PROPERTIES OF FUNCTIONALLY GRADED PLATES BASED ON THE guided waves

第七届海内外青年设计与制造科学会议

作者： Zhou Zhenggan Feng Zhanying and Gao Yifei School of Mechanical Engineering and Automation Beijing University of Aeronautics and Astronautics Beijing 100083 P. R. China

＜正＞The current research level of ultrasonic non-destructive testing in large structures is introduced. The characteristics of guided waves is presented;Some excitation methods are studied, and the comparison of merits and shortcomings and application among them is followed;The common signal processing methods with their prime characteristics and results are analyzed;Several typical application of guided waves are summarized. It is concluded that the ultrasonic guided waves would be developed continuously in the future because of their good qualities of quick speeds and the utility of near-surface defects inspection. However, owing to the complex dispersion, the inevitable noise and useless signal are met which results in the difficulties of extraction and analysis of the useful signal. Therefore some problems exist in current applications of guided waves.

关键词： Ultrasonic guided waves Large structure Disperse

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THE INVERSE OF MATERIAL PROPERTIES OF FUNCTIONALLY GRADED PL...

A SIGNAL PROCESSING METHOD OF DETECTING AND LOCATING MATERIAL DEGRADATION OR MICRO-CRACKS USING ULTRASONIC guided waves

2010全国压电和声波理论及器件技术研讨会

作者： Jian-gong YU~1,Wei-qiang MA~2 1 School of Mechanical and Power Engineering,Henan Polytechnic University,Jiaozuo 454003,P.R.China 2 Department of Information Engineering Hennan Vocational College of Chemical Technology, Zhengzhou 450042,P.R.China

Using guided wave characteristics of dispersion and multi-mode,an inverse method based on neural network (NN) is presented to determine the material properties of Functionally Graded Materials(FGM) *** group velocities of several lowest modes at several lower frequencies are used as the inputs of the NN model;the outputs of the NN are the distribution function of the volume fraction of the FGM *** Legendre polynomials method is used to calculate the dispersion curves for the FGM *** numerical simulation,the inversion work is carried out very easily and a satisfying result is obtained

关键词： Material properties plate functionally graded materials guided waves neural network dispersion

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A SIGNAL PROCESSING METHOD OF DETECTING AND LOCATING MATERIA...

guided wave propagation analysis in stiffened panel using time-domain spectral finite element method

第三届全国压电和声波理论及器件技术研讨会

作者： Bing WANG,Hong XU Key Laboratory of Condition Monitoring and Control for Power Plant Equipment(North China Electric Power University), Ministry of Education,Beijing 102206,China

The detection of micro-cracks or degradation of strength of materials at the early stage of fracture is of increasing importance in power plants and aviation industry.A methodology of detecting micro-cracks or degradation of material using quasi matrix pencil method is presented in this *** damage,is represented by small local elastic modulus *** of axisymmetric longitudinal guided waves to the presence of modulus reduction is studied using the Finite Element Method(FEM).Only the axisymmetric damage is considered *** using this method to calculate the dispersion relation of excited wave mode,the small modulus reduction can be *** the velocitY of excited guided wave and the time point at which the calculated dispersion curve changing,the damage can be *** this method can be used to find micro-cracks or material degradation at the early stage of fracture.

关键词： guided waves micro-crack material degradation elastic modulus reduction quasi matrix pencil method

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Chinese Journal of Aeronautics 2022年第10期35卷 208-221页

作者： Zexing YU Chao XU Jiaying SUN Fei DU School of Astronautics Northwestern Polytechnical UniversityXi'an 710072China Qingdao R&D Institute Northwestern Polytechnical UniversityQingdao 266200China

Stiffened panels have been widely utilized in fuselages and wings as critical load-bearing components. These structures are prone to be damaged under long-term and extreme loads, and their health monitoring has been a common concern. The guided wave-based monitoring method is regarded as an efficient approach to detect the damage in stiffened plates because of its wide monitoring range and high sensitivity to micro-damage. Efficient simulation of wave propagation can theoretically demonstrate the detection mechanism of the method. In this study, a Time-Domain Spectral Finite Element Method(TD-SFEM) is adopted to study the wavefield in stiffened plates,where continuous Absorbing Layers with Increasing Damping(ALID) strategy is proposed to circumvent the disturbance of reflected waves on boundaries. After the convergence analysis, the developed TD-SFEM with ALID is validated by the finite element method first. Then, wave scattering and the influence of the stiffener are investigated in detail by comparing the results with the non-stiffened structure. Finally, the effects of the parameters of the stiffener, such as the height and width, on wave propagation are studied, respectively. The results illustrate that the proposed TDSFEM with ALID is an efficient approach to study the wave propagation in the stiffened plate and can reveal the mechanism of influence of the stiffener. It is found that the height of the stiffener changes the interference of wavefield in the plate, while the effects of the width are mainly in wave scattering and mode conversion.

关键词： Absorbing layers with increasing damping guided waves Stiffened Panel Time-domain spectral finite element Wave propagation

Design of an Optical Water Pollution Sensor Using a Single-Layer guided-Mode Resonance Filter

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Photonic Sensors 2013年第3期3卷 224-230页

作者： Edward SADER Abdallah SAYYED-AHMAD Department of Physics Birzeit University Birzeit Palestine

The optical characteristics of a simple, planar, single layer, dielectric Mg-based guided mode resonance filter （GMRF） were investigated by means of rigorous-coupled wave analysis （RCWA）. This filter has great potential for real-life applications, especially as bio- and environmental sensors. The structure of the proposed sensor is compact, and all of its layers can be grown in a single process. In this paper, we present results on the design of a water pollution sensor in the violet region of the visible spectrum. The spectral and angular sensitivities of the sensor for both the transverse electric （TE） and transverse magnetic （TM） polarization modes were estimated and compared for various regions in the violet spectrum. A spectral response characterized with a narrow bandwidth and low reflection side bands was realized by carrying out extensive parameter search and optimization. Optimal spectral and angular sensitivities were found for the sensor with a grating thickness of 100nm in the TM polarized mode where we found them to be 100nm and 40 degrees, per index refraction unit, respectively.

关键词： Diffractive optics guided waves filters sensors spectral sensitivity angular sensitivity

Improving accuracy of damage quantification based on two-level consistency control of PZT layers

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Chinese Journal of Aeronautics 2023年第3期36卷 241-253页

作者： Yuanqiang REN Qiuhui XU Shenfang YUAN Research Center of Structural Health Monitoring and Prognosis State Key Lab of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Structural health monitoring-based quantitative damage diagnosis technique plays a key role in real-time condition *** the current research,piezoelectric(PZT)sensor and guided Wave(GW)based damage quantification methods are promising,which normally establish a calibration model between GW feature and damage degree by experiments on batch specimens,and then conduct the calibration model on the monitored ***,the accuracy of PZT and GW based damage quantification is affected by dispersion introduced by sensor network performance,structural material,and damage propagation among the adopted batch *** improving the accuracy of damage quantification,this paper adopts PZT layer as sensor network and creatively implements theoretical and experimental research on batch PZT layers consistency *** one hand,a two-level consistency control method based on multidimensional features-Euclidean distance is proposed to ensure the performance consistency of PZT layers placed on different *** the other hand,experimental research on typical aircraft lug structures is also carried out to evaluate the requirement on performance consistency of PZT layers when performing quantitative damage diagnosis,and further verify the proposed two-level consistency control *** results show that the accuracy of damage quantification raises by 38% when the dispersion of different PZT layers is controlled within 5%.

关键词： Consistency control guided waves PZT layer Quantitative damage diagnosis Structural health monitoring

Trapping Mechanism of Submerged Ridge on Trans-oceanic Tsunami Propagation

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China Ocean Engineering 2016年第2期30卷 271-282页

作者：郑金海熊梦婕王岗 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Nanjing Hydraulic Research Institute Nanjing 210029China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China The Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province Changsha University of Science and TechnologyChangsha 410076China

Based on the linear shallow water equations,an analytic solution of trapped waves over a symmetric parabolicprofile submerged ridge is *** trapped waves act as propagating waves along the ridge and as standing waves across the *** amplitude gets the maximum at the ridge top and decays gradually towards both *** decaying rate gets more gently with higher ***,an explicit first-order approximate dispersion relation is derived to simplify transcendental functions in the exact solution,which is useful to describe trapped waves over shallowly submerged ridges in ***,the trapping mechanism of the submerged ridge waveguides on the trans-oceanic tsunami propagation can be explained by the ray theory.A critical incident angle exists as a criterion to determine whether the wave is ***,a trapped parameter γ is proposed to estimate the ratio of the energy trapped by the oceanic ridge if a tsunami is generated at its top.

关键词： trapped waves guided waves shallow water equations analytical solutions tsunamis