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Inverse design of nonlinear phononic crystal configurations based on multi-label classification learning neural networks

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Chinese Physics B 2024年第10期33卷 295-301页

作者： Kunqi Huang Yiran Lin Yun Lai Xiaozhou Liu Key Laboratory of Modern acoustics Institute of AcousticsNanjing UniversityNanjing 210093China School of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China State Key Laboratory of acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China

Phononic crystals,as artificial composite materials,have sparked significant interest due to their novel characteristics that emerge upon the introduction of *** these properties,second-harmonic features exhibit potential applications in acoustic frequency conversion,non-reciprocal wave propagation,and non-destructive *** manipulating the harmonic band structure presents a major challenge in the design of nonlinear phononic *** design approaches based on parameter adjustments to meet specific application requirements are inefficient and often yield suboptimal ***,this paper develops a design methodology using Softmax logistic regression and multi-label classification learning to inversely design the material distribution of nonlinear phononic crystals by exploiting information from harmonic transmission *** results demonstrate that the neural network-based inverse design method can effectively tailor nonlinear phononic crystals with desired *** work establishes a mapping relationship between the band structure and the material distribution within phononic crystals,providing valuable insights into the inverse design of metamaterials.

关键词： multi-label classification learning nonlinear phononic crystals inverse design

Curved anisotropic polaritons

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Frontiers of physics 2024年第3期19卷 217-224页

作者： Tao Hou Yixiao Ge Shuwen Xue Huanyang Chen Department of Physics and institute of Electromagnetics and acoustics Xiamen UniversityXiamen 361005China Jiujiang research institute of Xiamen University Jiujiang 332000China

The curved surface has emerged as new research platform for understanding and manipulating novel electromagnetic behaviors in complex media. In this paper, we explore the anisotropic polaritons on the spherical surface based on Maxwell’s fish-eye metric through stereographic projection. Additionally, this phenomenon can be extended to spindle surface by conformal mapping. Our calculations and simulations demonstrate the elliptic and hyperbolic polaritons, excited by an electric dipole on the sphere, will self-focus or focus on the poles on the sphere affected by anisotropic permittivity. Furthermore, we reveal the optical singularity nature of the curved hyperbolic polaritons from the perspective of transformation optics by obtaining the equivalent optical refractive index profiles and the particle potential energy. Based on natural anisotropic materials and metamaterials, the curved polaritons have potential applications in curved surface focusing and chaos regulation. This work not only bridges the transformation optics and anisotropic polaritons at curved surface, but also provides a new route to surface optical field manipulation.

关键词： anisotropic polaritons transformation optics curved surface

A standing wave tube method for measuring acoustic and vibration characteristics of underwater acoustic materials

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Chinese Journal of acoustics 2024年第3期43卷 348-362页

作者： LI Shui YI Yan MO Xiping LIU Yongping HE Tao TONG Haoyang Hangzhou Applied acoustics research institute Hangzhou311400 institute of acoustics Chinese Academy of SciencesBeijing100190

A measurement method based on standing wave tube is proposed to get the acoustic and vibration characteristic parameters of underwater acoustic materials under hydrostatic pressure.A low-frequency emission transducer with pneumatic compensation is designed as the sound source for standing wave *** a water column,the planar piston vibration of the transducer is coupled to the sample under the water *** accelerometer is installed on the backing of the tested sample to measure the vibration velocity of the sample ***,a pair of hydrophones embedded in the tube wall is used to measure the sound pressure of the water *** on the measured data,the vibration velocity and sound pressure of the sample surface of incidence are *** vibration velocity transfer coefficient(decoupling coefficient)between the front and back surfaces of the sample,the input impedance,and the sound pressure reflection coefficient of the sample are then calculated.A low-frequency standing wave tube test system is constructed with a tube size of 300 mm inner diameter,600 mm outer diameter,and 3 m in height,with a frequency range of 100 Hz to 1000 *** experimental studies are conducted using water layer samples and multi-layer perforated rubber *** results show good agreement with the simulation data,thus validating the effectiveness of the measurement method.

关键词： surface method wave

CAGCN:Centrality-Aware Graph Convolution Network for Anomaly Detection in Industrial Control Systems

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Journal of Computer Science & Technology 2024年第4期39卷 967-983页

作者： Jun Yang Yi-Qiang Sheng Jin-Lin Wang Hong Ni National Network New Media Engineering research Center Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China

In industrial control systems,the utilization of deep learning based methods achieves improvements for anomaly ***,most current methods ignore the association of inner components in industrial control *** industrial control systems,an anomaly component may affect the neighboring components;therefore,the connective relationship can help us to detect anomalies *** this paper,we propose a centrality-aware graph convolution network(CAGCN)for anomaly detection in industrial control *** the traditional graph convolution network(GCN)model,we utilize the concept of centrality to enhance the ability of graph convolution networks to deal with the inner relationship in industrial control *** experiments show that compared with GCN,our CAGCN has a better ability to utilize this relationship between components in industrial control *** performances of the model are evaluated on the Secure Water Treatment(SWaT)dataset and the Water Distribution(WADI)dataset,the two most common industrial control systems datasets in the field of industrial anomaly *** experimental results show that our CAGCN achieves better results on precision,recall,and F1 score than the state-of-the-art methods.

关键词： graph convolution network(GCN) data mining network centrality anomaly detection industrial control system

High-order Bragg forward scattering and frequency shift of low-frequency underwater acoustic field by moving rough sea surface

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Chinese Physics B 2024年第3期33卷 459-470页

作者：莫亚枭张朝金鹿力成孙启航马力 Key Laboratory of Underwater Acoustic Environment Institute of AcousticsChinese Academy of Sciences (CAS)Beijing 100190China China State Shipbuilding Corporation Systems Engineering research institute Beijing 100094China Little Bird Co. LtdBeijing 100089China

Acoustic scattering modulation caused by an undulating sea surface on the space-time dimension seriously affects underwater detection and target ***,underwater acoustic scattering modulation from a moving rough sea surface is studied based on integral equation and parabolic *** with the principles of grating and constructive interference,the mechanism of this acoustic scattering modulation is *** periodicity of the interference of moving rough sea surface will lead to the interference of the scattering field at a series of discrete angles,which will form comb-like and frequency-shift characteristics on the intensity and the frequency spectrum of the acoustic scattering field,respectively,which is a high-order Bragg scattering *** the conventional Doppler effect,the frequency shifts of the Bragg scattering phenomenon are multiples of the undulating sea surface frequency and are independent of the incident sound wave ***,even if a low-frequency underwater acoustic field is incident,it will produce obvious frequency ***,under the action of ideal sinusoidal waves,swells,fully grown wind waves,unsteady wind waves,or mixed waves,different moving rough sea surfaces create different acoustic scattering processes and possess different frequency shift *** the swell wave,which tends to be a single harmonic wave,the moving rough sea surface produces more obvious high-order scattering and frequency *** same phenomena are observed on the sea surface under fully grown wind waves,however,the frequency shift slightly offsets the multiple peak frequencies of the wind wave *** with the swell and fully-grown wind waves,the acoustic scattering and frequency shift are not obvious for the sea surface under unsteady wind waves.

关键词： high-order Bragg scattering frequency shift low-frequency acoustic field moving rough sea surface

Numerical study on influence of protrusion heights on Reynolds stress and viscous stress variations in turbulent vortical structures

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Chinese Journal of Aeronautics 2024年第9期37卷 59-71页

作者： Zhiping LI Long HE Jingsai ZHOU Yueren ZUO Yao YIN Peng ZHANG Bo MENG research institute of Aero-Engine Beihang UniversityBeijing 100191China School of Energy and Power Engineering Beihang UniversityBejing 100191China institute of acoustics Chinese Academy of SciencesBeijing 100190China College of Aeronautical Engineering Civil Aviation University of ChinaTianjin 300300China AECC Hunan Aviation Powerplant research institute Zhuzhou 412002China

Analysing the infuence mechanism of the riblet protrusion height on turbulent drag components is more beneficial in organising the vortical structure over the riblet ***,the Large Eddy Simulation(LES)is used to investigate the vortex structure over the rib-let surface with different protrusion ***,the variations of Reynolds stress and viscous shear stress in a turbulent channel are *** a result,the drag reduction rate increases from 3.4%when the riblets are completely submerged in the turbulent boundary layer to 7.9%when the protrusion height is *** analysis shows that the protrusion height affects the streamwise vortices and the normal diffusivity of spanwise and normal vortices,thus driving the variation of Reynolds *** with the smooth surface,the vorticity strength and the number of streamwise vortices are weakened near the wall but increase in the logarithmic layer with increased protrusion ***,the normal diffusivity of spanwise vorticity decreases with the increase of protrusion height,and the normal diffusivity of normal vorticity is the smallest when the protrusion height is ***,the protrusion height affects the velocity gradient of the riblet tip and riblet valley,thus driving the variation of viscous shear *** the increase of protrusion height,the velocity gradient of the riblet tip increases dramatically but decreases in the riblet valley.

关键词： Riblet Dragreduction Protrusion height Vortical structure Vortexdiffusivity Reynolds stress Viscous stress

Anthropogenic noise interacts with the predation risk assessment in a free-ranging bird

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Current Zoology 2024年第3期70卷 277-283页

作者： Piotr Matyjasiak Patrycja Chacińska Piotr Książka institute of Biological Sciences Cardinal Stefan Wyszyński University in WarsawWóycickiego 1/3PL-01-815 WarsawPoland Department of Environmental acoustics Institute of Environmental Protection—National Research InstituteKolektorska 4PL-01-692 WarsawPoland

Anthropogenic noise can affect a number of behavioral,physiological,and ecological aspects of animals from major taxonomic groups,raising serious conservation *** example,noise pollution impacts communicative behavior and perception of signals,movements and distribution,as well as predator–prey interactions,such as hunting success or predator detection and predation risk *** have carried out an experimental playback study,in which we investigated whether exposure to anthropogenic noise(sound of a tractor)distracts free-ranging barn swallows Hirundo rustica from paying attention to an approaching human“predator”(the“cognitive distraction”hypothesis),or whether noise leads to increased responsiveness to this“predator”(the“increased threat”hypothesis).The subjects were male barn swallows attending their breeding territories during the time when the females were *** found that barn swallow males initiated fight at signifcantly greater distances to the approaching human“predator”in the noise treatment than during the quiet control *** results suggest that anthropogenic noise causes increased vigilance and reactivity rather than a distraction,enabling birds to avoid the“predator”more *** further discuss the mechanism behind the increased alertness in response to noise and contrast the“increased threat”mechanism,usually tested in previous studies,with an alternative“cognitive sensitization”mechanism.

关键词： anthropogenic noise barn Swallow cognitive distraction flight initiation distance Hirundo rustica predation risk assessment

Acoustic Purcell effect induced by quasibound state in the continuum

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Fundamental research 2024年第1期4卷 57-62页

作者： Sibo Huang Shuhuan Xie He Gao Tong Hao Shuang Zhang Tuo Liu Yong Li Jie Zhu institute of acoustics School of Physics Science and EngineeringTongji UniversityShanghai 200092China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China College of Surveying and Geo-Informatics Tongji UniversityShanghai 200092China Department of Physics The University of Hong KongHong Kong 999077China Key Laboratory of Noise and Vibration research Institute of AcousticsChinese Academy of SciencesBeijing 100190China The Hong Kong Polytechnic University Shenzhen research institute Shenzhen 518057China

We study theoretically and experimentally the acoustic Purcell effect induced by quasi-bound states in the continuum(quasiBICs).A theoretical framework describing the acoustic Purcell effect of a resonant system is developed based on the system’s radiative and dissipative factors,which reveals the critical emission condition for achieving optimum Purcell *** show that the quasiBICs contribute to highly confined acoustic field and bring about greatly enhanced acoustic emission,leading to strong Purcell *** concept is demonstrated via two coupled resonators supporting a Friedrich-Wintgen quasiBIC,and the theoretical results are validated by the experiments observing emission enhancement of the sound source by nearly two orders of *** work bridges the gap between the acoustic Purcell effect and acoustic BICs essential for enhanced wave-matter interaction and acoustic emission,which may contribute to the research of high-intensity sound sources,high-quality-factor acoustic devices and nonlinear acoustics.

关键词： Acoustic Purcell effect Bound state in the continuum Mode coupling Sound emission enhancement High-quality-factor acoustic device

Robust asymmetric Cherenkov radiation in tilted anisotropic medium

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 46-51页

作者： Shuwen Xue Yadong Xu Linkang Han Zhi Ning Chen Qiaoliang Bao Shan Zhu Huanyang Chen institute of Electromagnetics and acoustics and Department of Physics College of Physical Science and TechnologyJiujiang Research InstituteXiamen UniversityXiamen 361005China School of Physical Science and Technology Institute of Theoretical and Applied PhysicsSoochow UniversitySuzhou 215006China Department of Electrical and Computer Engineering National University of SingaporeSingapore 8117583Singapore institute of Energy Materials Science(IEMS) University of Shanghai for Science and TechnologyShanghai 200093China

Cherenkov radiation(CR)is available for a wide variety of terahertz(THz)radiation sources,but its efficiency is deeply affected by intrinsic *** find that if the tilted angle(α)of anisotropic material and radiation angle(θ)meet the condition ofθ+α=π/2,the intensity of radiation fields for the charged particle bunch(CPB)moving from left to right cannot be influenced by intrinsic losses,which means long-distance radiation can be ***,we observe an asymmetric CR when the CPB moves from the opposite *** addition,we select natural van der Waals(vd W)materialα-MoO3as an example,further confirming that the radiation field can reach the far field and the asymmetric CR radiation can also be *** wonderful properties with long-distance radiation will extend the application of CR to a certain extent for future design and fabrication.

关键词： asymmetric Cherenkov radiation intrinsic losses long-distance radiation