bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bio-inspired target detection method of active sonar based on multi-ping perception
Authors: Wang Qingcui , Wang Fangyong , Du Shuanping , Lin Yuxin 
Published: October 2024

Abstract
The performance of the active sonar may degrade severely in real ocean environments, influenced by strong reverberation and multiple clutters. Inspired by the observation that dolphins always utilize a train of clicks when detecting underwater, we proposed an active target detection method by making full use of the multi-ping echo information which encompasses the differences between targets and reverberation/clutters. The detection performance of the click trains with different parameters were analysed first to give an insight on signal choice. Then we achieved apparent reverberation/clutter suppression result by utilizing the correlations and differences between multi-ping echoes. Further, the relative motion status between the target and the sonar platform could be perceived within multiple echoes, which strengthened the detection ability of weak target. We proposed two weighting strategies for multi-ping co-utilization. Either equal weights or unequal weights based on the different envelopes of dolphin echolocation click trains were exerted on multiple echoes, which can achieve different perception results for the relative target motion status. Both simulation and lake trials were conducted to verify the performance of the proposed method. The proposed method effectively suppress reveberaton and noise background by around 2-3 dB and achieve bionic detection of weak targets compared to traditional active sonar signal processing method.
Research on SNR enhancement method of underwater airgun impulse signal
Authors: Ma Siyu , Zhang Yuxiang , Xie Zhinan 
Published: October 2024

Abstract
Seismic airgun blasting is nowadays widely employed for ocean exploration and marine geophysical study. Being powerful acoustic source showing excellent repeatability and consistency, it’s potentially applicable for long-distance underwater acoustic communication. Given the sound generating mechanism of airguns, the generated signals cannot be modulated compared with sources signals that are more commonly used for communications purposes. Thus the use of time delay shift coding system, which is both necessary and advantageous under such circumstances. The detection of the impulsive signal from airgun blasting and accurate estimation of its arrival time at the receiving end is paramount for carrying out a time delay shift coding communication. Consequentially, augmentation of the signal-to-noise ratio (SNR) of received signal through enhancement is the most direct and effective approach. This manuscript presents an enhancement method of the airgun blasting signals: A recursive wavelet modulus maxima denoising method is introduced, by separating the raw signals into noise components and signal components iteratively, details information that is erroneously erased by conventional wavelet modulus maxima denoising method can thus been preserved. Coupled with the proposed use of a loop coefficient of determination, automatic balancing between denoising effectiveness and distortion of valid signals is acrhieved.
Functional-analytical solution of ocean acoustic tomography problem
Authors: Shurup A.S. 
Published: October 2024

Abstract
A three-dimensional scheme of mode adiabatic tomography of sound speed inhomogeneity in a shallow sea based on a two-dimensional functional-analytic algorithm is proposed and numerically investigated. To reconstruct three-dimensional scatterers from two-dimensional functions recovered by solving inverse problems for individual modes, Karhunen-Loeve functions are used, which allows to reduce the number of unknowns in solving the inverse problem. It is shown that the proposed scheme has a high resolution in horizontal plane when recovering high-contrast inhomogeneities. The solution of coupled Lippmann-Schwinger equations describing the effects of multichannel mode scattering is numerically implemented to model the scattering data. The presented numerical results illustrate possibility of achieving acceptable noise immunity of the regarded scheme using a broadband sensing regime and a series of repeated experiments.
Study on ultrasonic lamb wave testing technology of honeycomb sandwich structures
Authors: Wang Du , Cai Suyang , Wang Hongyuan , Chen Zhenhua , Huang Hui , Chen Dingyue , Wu Caibao 
Published: October 2024

Abstract
Honeycomb sandwich composite panels have complex structures, large sizes, many types of defects, and significant sound attenuation, which lead to low efficiency and poor sensitivity of ultrasonic non-destructive testing. In the study, a non-linear ultrasonic lamb wave testing technique for honeycomb sandwich composite panels is proposed. Firstly, the anisotropic propagation characteristics and modal structure of lamb waves in honeycomb sandwich composite panels are analyzed, and the lamb wave modes with non-linear ultrasonic accumulation are excited. Secondly, the data extraction method and imaging algorithm of non-linear ultrasonic lamb wave imaging testing are proposed. Finally, an enhanced imaging algorithm is proposed to improve image quality based on the sliding window algorithm. Based on the comparative analysis of air-coupled ultrasonic testing images and metallographic tests, it can be seen that non-linear ultrasonic lamb wave testing signals can be used to characterize the damage distribution characteristics of honeycomb sandwich composite panels, display debonding and weak debonding defects, and have the advantages of being able to perform on the same side testing and high efficiency, which can be used for non-destructive testing of honeycomb sandwich composite panels.
Ultrasonic testing method for impeller brazing defects with refraction wave perpendicular to brazing surface and angle amplitude compensation
Authors: Zhou Shiyuan , Cao Yuxin , Du Peicheng , Liu Luhang , Zheng Chong 
Published: October 2024

Abstract
There are blind areas in ultrasonic brazing defect detection, due to the non-parallel brazing surface and outer surface for many components including impeller. In this paper an oblique incident ultrasonic testing method with a refraction wave perpendicular to brazing surface is proposed. Meanwhile, an incident angle amplitude compensation is implemented to decrease the influence of the defect echo amplitude difference caused by oblique incidence and unify the sensitivity of different scanning positions. The compensation curve based on the theoretical curve of echo energy at different incident angles is optimized with iteration of actual measured defect echo amplitude. In order to prove the need for ultrasonic testing method with a refraction wave perpendicular to brazing surface, bottom surface echo test for conical samples is operated. In addition, with the method proposed in this paper, scanning image of impeller sample with the same detection sensitivity is obtained successfully. Testing results suggest that in relation to old method with incident wave perpendicular to the outer surface, the method proposed in this paper can solve the blind area problem effectively.
Acoustic Metasurfaces for Efficient Modulation and Demodulation of OAM Multiplexed Signals in Acoustic Communication
Authors: Liu Zhi , Huang Baolin , Lin Wei 
Published: October 2024

Abstract
Orbital angular momentum (OAM) multiplexing has been suggested as a potential solution to increase the data capacity of acoustic communication systems. A method of modulation and demodulation of OAM multiplexed signals using acoustic metasurfaces is proposed in this manuscript. The amplitude and phase of independent acoustic orbital angular momentum (AOAM) multiplexed signal provide orthogonal degrees of freedom. By designing appropriate acoustic metasurfaces and combining them with binary differential phase coding techniques, we demonstrated that efficient modulation and fast demodulation of AOAM multiplexed signals can be achieved. Orthogonal acoustic spiral modes prevent mode coupling and crosstalk, enhancing acoustic multiplexing. The resonance-based structure provides signal frequency selectivity, boosting efficiency and simplifying terminal equipment for practical applications, which leads to the creation of high-capacity acoustic communication systems.
Two-step scattering theory method for designing metamaterials
Authors: Dmitriev K V , Smirnykh D V 
Published: October 2024

Abstract
A two-step method for designing an acoustic metamaterial with desired properties is proposed. At the first step, the scattering matrices of its elements are calculated using the Lippmann-Schwinger type equation. For scatterers of small wave size, the problem is reduced to determining the phases of several scattering coefficients. At the second step, the particular design of metamaterial elements is determined. This problem can be considered an inverse scattering problem or a problem of optimizing the geometric parameters of a metamaterial element. The second approach turns out to be more practically applicable. As an example, a metamaterial in the form of a reflective layer with a narrow waveguide channel is considered, and the design of its elements is determined with the proposed method.
Nonlinear dynamics of a bubble cluster in liquid cavity wrapped by elastic medium
Authors: Zhang X M , Zuo X Y , Li W N , Wang C H 
Published: October 2024

Abstract
According to the modified nucleation theory, gas nuclei can generate and grow into cavitation bubbles when’s the liquid pressure exceeds a threshold in a cavity. Based on the modified nucleation theory, the growth process of the gas nuclei in a liquid cavity can be simplified to two “events”, and the full confinement effects of the surrounding elastic medium of the cavity was considered by including the bulk modulus in the equation of state. The dynamical equations were derived to model the nonlinear oscillation of the multi-bubble system in the cavity. The effects of acoustic parameters, the initial radius and the total number of bubbles on bubble dynamics were investigated numerically. It is found that bubble behaviors are sensitive to the acoustic field. In the low frequency region (f <1MHz), bubble oscillation exhibits a modulated waveform, and fundamental, subharmonic and harmonic modes can be found in the acoustic response curve. The oscillations of confined bubbles diminish with increasing frequency. In the high frequency region (f >1MHz), the confinement state affects the acoustic response of the gas nuclei, and the growth rate differ by a factor of 5 difference in the presence of shelled or unbounded elastic confinement of the cavity. Therefore, the suppression or enhancement of cavitation growth and collapse in confined cavity can be modulated by a variety of factors, such as the total number of nuclei, cavity size, acoustic frequency and amplitude, negative pressure, and elastic medium, which have a synergistic influence on the confined cavitation process.
The velocity fields around aspherical bubbles
Authors: Wu Y R , Wang C H 
Published: October 2024

Abstract
This paper studies the simplest system, which can possess the left-right symmetrical and asymmetrical surroundings, three bubbles in a line. Assuming that the deformations are small, the surfaces of bubbles are described by a combination of the first three Legendre polynomials, that is, spherical symmetrical mode P0, antisymmetrical mode P1 and symmetrical mode P2. Based on the dynamics of three-bubble system, this paper further studies the velocity fields distribution around them. It can be seen from the contour distribution of the velocity field that the velocity component always decreases with the increase of the distance r. When three identical bubbles are separated uniformly, the velocity field around the central bubble is always in a symmetric, while there are asymmetric velocity fields around two side bubbles.
Angular spectrum method for acoustic beam in anisotropic media and structures
Authors: Xu Wei-Jiang , Zhang Jin-Ying , Wu Xian-Mei , Cheng Qian , Dupont Samul 
Published: October 2024

Abstract
The Angular Spectrum (AS) method is commonly used to calculate the propagation of scalar wave fields. This study extends the application of AS to vector wave propagation, specifically addressing acoustic waves in anisotropic media. The approach involves using plane wave spectra to express all possible mode waves, namely one q-P wave and two q-S waves, that propagate in various directions in the medium. These AS are determined by applying boundary conditions at the source surface where the vector waves are generated and the modes waves are coupled. AS decomposition of waves requires the determination of complex wavenumber vectors (or slownesses) through the Christoffel equation, including both propagating and evanescent waves. The determination of the acoustic beam profile in TeO2 crystals is presented as an application example of AS.
High Sensitivity Performance of Piezoelectric Micromachined Ultrasonic Transducer Employing Sc-Doped AlN Thin Film
Authors: Liu Xiaonan , Zhang Qiaozhen , Chen Mingzhu , Zhao Xiangyong 
Published: October 2024

Abstract
Aluminum Nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) have been the prime choice in acoustic imaging, because it has advantages of high frequency and thus high resolution. However, low piezoelectric constants of AlN gives rises to limitation in transmitting sensitivity. Scandium (Sc) doping method for AlN can be used to improve its piezoelectricity. In this paper, single element PMUT based on ScAlN thin film was proposed and modeled by performing finite element method (FEM). Influence of different electrode configurations on PMUT performance were studied. The results show that, compared with other electrode configurations, PMUT has the best overall performance when the upper electrode is platinum (Pt) and the lower electrode is molybdenum (Mo). In addition, the acoustic field characteristics and its dynamic analysis of PMUT based on ScAlN in water were studied. The investigation results demonstrated that the relative pulse-echo sensitivity level M of PMUT is significantly improved with the increase of Sc doping concentration in AlN thin film. When the Sc concentration is 40%, the M reaches -44 dB, which is 20 dB higher than that without Sc (-64 dB). The PMUT based on the high Sc-doped AlN thin film has a larger effective electromechanical coupling coefficient and sensitivity, which is beneficial to the application in high sensitivity ultrasound imaging.
Acousto-optic femtosecond laser beam shaping for bottle-beam generation
Authors: Obydennov Dmitry , Yushkov Konstantin , Molchanov Vladimir 
Published: October 2024

Abstract
This study explores the properties of a laser beam shaping system comprising an acousto-optic dispersive delay line (AODDL) and an acousto-optic tunable filter (AOTF) for ultrashort laser pulse shaping. The system demonstrates the AODDL’s ability to generate signals with arbitrarily positioned transmission windows and investigates the impact of spectral width on field distributions. The AOTF’s frequency scanning and simultaneous control of two and three spectral components are presented. The experimental setup utilizes femtosecond laser radiation, and the results highlight the system’s versatility for programmable spectral and spatial filtering, offering potential applications in advanced optical manipulation.
A pulse-echo measurement setup to determine viscoelastic material parameters
Authors: Dreiling Dmitrij , Itner Dominik , Hetkämper Tim , Birk Carolin , Gravenkamp Hauke , Henning Bernd 
Published: October 2024

Abstract
Due to their versatility, the application of polymers in research and industry continues to increase. Since the majority of design processes are simulation-aided, precise material parameters are required to obtain realistic results. The quasi-statically and destructively measured material parameters provided by manufacturers for this purpose are usually insufficient. An acoustic method is generally capable of measuring the frequency-dependent viscoelastic material parameters in a non-destructive manner. In particular, an ultrasonic transmission measurement setup for determining these parameters has already been presented in previous publications. However, this approach has several drawbacks, including a low sensitivity to shear parameters. To increase the sensitivity to shear parameters, a measurement setup using a pulse-echo method with a corresponding inverse approach is presented to obtain viscoelastic material parameters of polymers. A brief comparison is made between the transmission and pulse-echo methods.
Enhancement in performance of SAW resonator on LN/SiC substrate by take slowness asymmetry into account
Authors: Liu H L , Zhang Q Z , Sun H , Yang Y , Gu Y D , Wang N 
Published: October 2024

Abstract
Layered structures comprising high-coupling lithium niobate (LiNbO3, LN) piezoelectric thin plates bonded to high-velocity SiC substrates have attracted much attention of high-performance surface acoustic wave (SAW) devices. However, such these layered structures exhibit severe Rayleigh mode spurious responses that degrade the performances of SAW devices. This paper explores the generation mechanism of spurious modes on LN/SiC layered structure, and proposes an optimized layered structure with suppressed Rayleigh spurious modes. The investigation involves deriving the Euler angle range of LN by analysing the slowness surface of both LN and SiC. In addition, it is worth noting that slowness surface overlaps at some Euler angle ranges, which will cause coupling between different modes, thus generating spurious mode. Simulation result shows the frequency characteristics of SAW resonator at resonant and anti-resonant frequencies of 4.3 GHz and 4.88 GHz of SH mode, achieving a K
2 of up to 26.5% and a quality factor Q of 828. It is proved that the optimization structure offering larger K
2, higher velocity and improved Q values and Rayleigh spurious mode suppression, which is favourable for wideband and high frequency SAW devices applications.
Defect Recognition and Classification Using Ultrasonic Scattered Signals Based on Convolutional Neural Network
Authors: Chen Yuanyuan , Shi Fangfang , Kong Chao 
Published: October 2024

Abstract
Carbon Fiber Reinforced Polymer (CFRP) is widely used in the aerospace, aircraft, and railway industries because of its remarkable advantages, such as its lightweight and high strength. Detecting and identifying defects in CFRP is crucial for ensuring its secure and efficient use. Ultrasonic non-destructive testing is one of the most practical and effective methods for defect detection and identification. The ultrasonic scattered signals of defects, which contain abundant defect feature information, are advantageous for defect recognition and classification. However, the anisotropy and inhomogeneity of CFRP, which lead to a low signal-to-noise ratio and poor image quality, pose challenges in flaw recognition. To address the issue, this paper proposes using Convolutional Neural Networks (CNN) methods for defect classification, which can adequately extract information from ultrasonic scattered signals directly. The scattering signals from various types of defects in CFRP, including the different sizes of holes and folds, were selected as inputs for CNN models. Different network models combining Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) with 1D-CNN were employed to classify and identify defect signals. To generate sufficient input sample signals, the data sets were further enlarged by incorporating noise into the original signals. The experimental results showed that using the 1D-LSTM-CNN and 1D-GRU-CNN network models can reduce computational resources while ensuring the accuracy of defect recognition.
Numerical simulation of scattering of TWIPS by underwater air bubble
Authors: Li Feishan , Zhang Yuxiang , Sheng Xueli , Zhang Jiangyi 
Published: October 2024

Abstract
The interaction of water with the subsurface of sea-ice leads to the generation of air bubbles. This heterogeneity results in additional challenges for unmanned underwater vehicles (UUV) conducting active detection in the upper water column of the Arctic Ocean. Under excitation by a high-amplitude acoustic source, asymmetric oscillations of the bubble are generated due to the high compressibility of gas, which further leads to acoustic scattering showing nonlinear characteristics. The corresponding signals may interfere with or even mask the echoes from potential targets, which are often linear scatterers, ultimately impairing the UUV’s active sensing capabilities under the sea-ice. Twin Inverted Pulse Sonar (TWIPS) is an underwater detection technique consisting of sending two pulse signals of equal amplitude but with opposing phases, benefiting from the difference in the responses of the bubble and target and the resulting echo signals for the eventual distinguishing. In this study, a numerical modeling of underwater bubbles for the acoustic study is developed by making use of both multiphysics and moving mesh features of Comsol. Numerical simulations were conducted to investigate the nonlinear feature of acoustic scattering from air bubbles. These results are then compared with analytical results for verification. Monochromatic signals and TWIPS at different frequencies are used as excitation signals, and the response of spherical air bubbles and the resulting scattered wave field are calculated, compared, and analyzed.
Defect recognition and classification from ultrasonic phased array total focusing method imaging based on domain adaption
Authors: Wang Haibin , Cheng Jingwei , Chen Wei , Li Rui , Wang Zhe , Bu Yangguang , Tang Jian , Yan Chang , Ji Tian , Li Kang , Liu Jiapeng 
Published: October 2024

Abstract
With the rapid development of China’s economy, the demand for oil and gas resources is continuously increasing, leading to the expansion of the scale of oil and gas long-distance pipelines. Consequently, the risk of safety incidents in oil and gas pipelines is on the rise. Welding defects are identified as one of the significant factors contributing to safety incidents in long-distance oil and gas pipelines. In comparison to traditional conventional ultrasonic detection techniques, which exhibit low efficiency and accuracy, ultrasonic phased array detection technology has the capability to accurately detect welding defects in oil and gas long-distance pipelines. This is particularly true with the development of total focusing method imaging technology, enabling quantitative defect analysis and localization in oil and gas long-distance pipelines.However, in the current scenario, analyzing the types of defects in massive data from long-distance pipelines requires human intervention, leading to low detection efficiency and subjective influence on result analysis. Addressing challenges such as low efficiency in human evaluation of defects in ultrasonic phased array detection, low accuracy in traditional image recognition methods, strong subjectivity in manually extracting features, and the absence of a standardized industrial dataset for ultrasonic phased array detection defects, especially in the case of limited data on ultrasonic phased array detection of welding defects, this study focuses on small sample defects in phased array detection images. The study proposes an improved ResNet50 algorithm through domain adaptation in a deep neural network, trained on a large-scale model data, and then applied to ultrasonic phased array detection data. This approach achieves accurate identification and classification of typical volumetric defects (such as pores) and typical area defects (such as cracks) in the phased array detection of welding defects, laying the foundation for intelligent recognition of defects in long-distance oil and gas pipelines.