- CHEN Jingwen;ZHANG Shiwei;NIU Gege;SU Mingxu;CAI Xiaoshu;
The influence of bubbles shape on acoustic behavior plays a crucial role in studying the characteristics and parameter detection of gas-liquid two-phase flow. A Monte Carlo prediction model for ellipsoidal bubbles is developed for a non-spherical bubble system, which combines the Monte Carlo method with the T-matrix method. Based on the model, the attenuation coefficient of the millimeter-sized ellipsoidal bubble cluster at the frequency of 50–500 kHz is calculated in numerical simulation, revealing the variation rules of the attenuation coefficient and the acoustic behaviors with the bubble morphology and size. The results show that, with the elongation of a bubble, the forward amplitude of the scattered sound pressure decreases and the backward amplitude increases; the scattered sound pressure exhibits angular redistribution and directional deformation depending on the incident direction. The anechoic efficiency tends to enhance with bubble elongation,particularly at low dimensionless parameters. The transmission behavior of sound waves in the bubble cluster goes down with the amplification of the major-to-minor axis ratio of the ellipsoid, while the scattering behavior exhibits the opposite trend. The attenuation coefficient climbs with both the elevation of the acoustic wave incidence angle and the major-to-minor axis ratio. Notably, when the major-to-minor axis ratio exceeds 1.1, a measurable change in attenuation coefficient occurs. The attenuation coefficient diminishes with the enlargement of bubbles, and its rate of change becomes less pronounced. For the bubble cluster with a mean radius of 2.5 mm obeying a normal distribution function, the acoustic attenuation coefficient augments as the radius distribution broadens. Specifically,when the standard deviation of this distribution is raised to 0.5 for bubbles with a radius of 2.5 mm, there is a 6.51% increase in the attenuation coefficient.
2025年03期 v.44 257-271页 [查看摘要][在线阅读][下载 883K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - LI Qianwen;WANG Ping;WANG Peng;WANG Kunlin;
The coherence factor of a single parameter is difficult to simultaneously improve the resolution and contrast of ultrasound images in complex imaging scenarios.Therefore, an ultrasound imaging algorithm combining optimal apodization function and multi-parameter composite conditional factor(OA-MCCF) is proposed to improve the overall image quality. Firstly, several sets of apodization window functions are weighted on the received echo signals, and the optimal apodization function is selected based on the principle of minimizing the variance of the beamformer output. Secondly, the selected apodization function is weighted onto the echo signals to obtain the optimized array signals, and the current conditional coherence is calculated by the signals at multiple sampling times. Finally, the weighted factor is obtained by composing the conditional factors with multiple parameters according to the global image coherence information. The simulated and experimental results demonstrate that, compared with the traditional delay-and-sum algorithm, the proposed OA-MCCF algorithm can significantly enhance image resolution and contrast. Specifically, the OA-MCCF algorithm can achieve the greatest improvements in full width at half maximum of 89.23% in the point-target simulation and 63.22% in the carotid longitudinal-section experiment. Compared with the traditional coherence factor algorithm, the proposed algorithm improves resolution performance while maintaining image contrast.
2025年03期 v.44 272-286页 [查看摘要][在线阅读][下载 1087K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - TIAN Yongsheng;XIANG Yu;YUAN Liyun;WU Wenjun;LU Jing;WU Song;
Based on Fourier transform, the angular spectrum equation and its discrete model of the inverse source problem of the two-dimensional Helmholtz equation are derived. By transforming the two-dimensional inverse source problem in the spatial domain into the inverse source problem in the one-dimensional Fourier domain, the source intensity angular spectrum vector in the Fourier domain is calculated by the one-dimensional method of moments. Then, using the discrete Fourier inverse transform, a multi-frequency angular spectrum method of moments is proposed to reconstruct the inverse source problem of the two-dimensional Helmholtz equation. The reconstruction accuracy and stability of this method are improved by optimizing the excitation wavenumber sequence. Simulation calculations show that the multi-frequency angular spectrum method of moments has high reconstruction accuracy and anti-noise ability, and can also design the reconstruction model according to the effective frequency band of the acoustic sensor to achieve the highest resolution. In addition, since the calculation of the coefficient matrix of the proposed method is independent of the distribution of the source intensity function and does not require regularization processing, when the size and resolution of the required source intensity distribution area are determined, after the coefficient matrix is calculated and saved,the source intensity function corresponding to the region of interest can be reconstructed according to different sound pressure detection data, with high calculation accuracy and efficiency.
2025年03期 v.44 287-310页 [查看摘要][在线阅读][下载 2679K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - NI Haiyan;LU Licheng;REN Qunyan;MA Li;
To acquire information on the distribution and properties of seafloor sediments, the coupling relationship of sediment parameters in the seafloor high-frequency scattering model is analyzed for sediment classification. Initially, based on the Sternlicht high-frequency scattering model, the time-domain echo pressure envelope from single-beam echosounder is simulated. Then, the coupling relationship of sediment parameters(index of impedance, spectrum intensity, spectrum index and volume scattering coefficient) is analyzed for different seafloor sediment types in shallow water. Finally, the fitting line slope of the coupling fringe is extracted from the experimental data conducted in Qingdao offshore to classify seafloor sediment types. The simulation results based on the high-frequency scattering model show that three sediment parameters(index of impedance, spectrum intensity, and spectrum index) are sensitive and coupled to each other. They jointly affect the intensity of the time-domain echo pressure envelope, which is directly related to different sediment types. Therefore, different sediment types can be classified by the coupling relationship of acoustic characteristic parameters. The experimental results show that the soft and hard sediment types can be effectively distinguished by the fitting line slope of the coupling fringe.
2025年03期 v.44 311-327页 [查看摘要][在线阅读][下载 1548K] [阅读次数：1 ] |[下载次数：1 ] |[引用频次：0 ] - LI Quan;LIU Xia;ZHAO Hangfang;
The localization performance of matched-field processing decreases substantially for high-mismatch and high-frequency localization scenarios. Based on incoherent frequency-difference source localization technique and data-driven machine learning localization method, this paper proposes a convolutional neural network localization method based on the cross-spectral density matrix of coherent frequency-difference signal. This method utilizes dual-driven modeling and data to localize mid-to high-frequency underwater sources in mismatched and noisy scenarios. For frequency-difference signals, this method performs incoherent averaging along the central frequency dimension to reduce the influence of cross-term, and stacks along the frequency-difference dimension to preserve the correlation information between different frequencies. The resulting tensor data is then used as input to a convolutional neural network for underwater source localization.This paper conducts experiments using the Swell Ex-96 simulation environment and sea trial data from the 2021 South China Sea Acoustic Tomography Long-Range Experiment.The experiments show that the proposed localization algorithm is suitable for localizing medium and high frequency sources in the noise-containing and mismatch-existing marine environment, showing favorable tolerance for underwater source localization.
2025年03期 v.44 328-347页 [查看摘要][在线阅读][下载 1595K] [阅读次数：1 ] |[下载次数：3 ] |[引用频次：0 ] - XING Chuanxi;LU Mao;MENG Qiang;TAN Guangzhi;RAN Yanling;
To address the issue of low estimation performance of the traditional off-grid sparse Bayesian learning algorithm in the complex shallow-water localization environment for acoustic target direction estimation, this paper proposes a real-domain out-of-state sparse Bayesian learning algorithm that combines dictionary learning and unitary transformation for direction estimation. The algorithm employs the K-means singular value decomposition dictionary learning method to represent the actual received signal of a uniform linear array using a small number of linear combinations of basic received signals,thereby achieving noise reduction for the original signal. The denoised signal matrix is then constructed into a processing matrix that satisfies the central Hermitian property.By applying a unitary transformation, the signal data is converted from complex-domain operations to real-domain operations, which reduces computational complexity. Finally,singular value decomposition and outlier sparse Bayesian learning algorithms are used for iterative processing to achieve target direction estimation. Simulation analysis and sea trial data results demonstrate that compared with the off-grid sparse Bayesian learning algorithm, under conditions of low signal-to-noise ratio and low frame rate, the proposed algorithm has improved azimuth estimation accuracy and algorithm robustness, and is less complex.
2025年03期 v.44 348-371页 [查看摘要][在线阅读][下载 1171K] [阅读次数：1 ] |[下载次数：1 ] |[引用频次：0 ] - SHENG Xueli;WANG Yan;WAN Linna;WU Zeyi;SHI Bingyu;LI Dewen;
In order to solve the problem of discontinuity of target tracking and large number of false alarm targets given to the same target by multi-node sonar system, a joint SVM-GAN algorithm for interrupted track association connection is proposed. Based on the association of acoustic features of the target track before and after the interruption,support vector machine(SVM) is used to establish the association relationship among the spatio-temporal non-overlapping tracking tracks, and the generative adversarial network(GAN) is used to continue the track set which is formed the association relationship.Meanwhile, a feedback mechanism is established to synchronically place the complete track into the training set to improve the adaptability of the algorithm to the application environment. The simulation and measured data processing results show that the proposed method can correlate the track with the acoustic characteristics of the target and track the interrupted track continuously. The association accuracy is more than 80%, and the number of false alarms is effectively reduced. It can be used for large range acoustic target monitoring at sea.
2025年03期 v.44 372-392页 [查看摘要][在线阅读][下载 2148K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - LIU Chao;
For the constant false alarm rate(CFAR) detection problem of active sonar in complex environment and propagation channel, an automatic CFAR detection method of active sonar based on hierarchical filters was proposed. Firstly, based on the spatial response characteristics of the array and the morphological characteristics of the target echo,a spatio-temporal filter was designed to remove the background noise and reverberation signal. Then, a linear and nonlinear combined spatial filter were designed to extract the energy accumulation area of the active sonar sonogram. Finally, the multi-dimensional features such as the spatial azimuth distribution of the target echo, the shape matching and the signal-to-noise ratio between the accumulation point and the adjacent background were calculated and fused to realize the target detection. Numerical simulation and sea test data show that, the probability of automatically detecting targets by this algorithm is larger than 85% in three typical cases, and this algorithm can detect targets when the background noise fluctuates greatly, showing that the algorithm is more robust.
2025年03期 v.44 393-416页 [查看摘要][在线阅读][下载 3697K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - CUI Hongyu;DENG Jinhao;YAO Yan;HONG Xiaoping;SUN Dajun;
In order to solve the problem that the conventional Doppler estimation method of single carrier frequency domain equalization system is not accurate or high complexity is required for high-precision estimation, a Doppler estimation algorithm based on complex autocorrelation amplitude and phase information of velocity measurement signal is proposed in this paper. Firstly, the amplitude information is used to complete the Doppler rough estimation, and the rough estimation results are used to solve the ambiguous problem of the phase method, so as to obtain high-precision Doppler estimation results. Simulation results show that the proposed algorithm has high Doppler estimation accuracy and low computational complexity. The lake test data analysis results show that in the scenario of communication distance of 2 km, bit rate of 5 kbit/s and speed of 3 m/s, the proposed Doppler estimation method is capable of providing high-precision Doppler estimation results and significantly improving the bit error rate performance compared with the conventional methods.
2025年03期 v.44 417-436页 [查看摘要][在线阅读][下载 1082K] [阅读次数：1 ] |[下载次数：0 ] |[引用频次：0 ] - ZHANG Wenwen;JIA Zhenyu;ZHANG Rongxin;YUAN Fei;
Leveraging the correlation between the received signal of sweep-spread carrier(SSC) in a multipath channel and the orthogonal chirp division multiplexing(OCDM)symbol,this paper introduces the discrete Fresnel transform(DFnT) and proposes a lowcomplexity SSC demodulator.Within this framework,most multipath components in SSC are treated as subcarriers within the OCDM system and are filtered out using the DFnT.Training symbols are then employed to record the phase shifts caused by residual nearby multipath,and a deflected constellation diagram is utilized for the direct demodulation of data symbols.Compared to the traditional demodulation and equalization methods,the strategy of using DFnT transform in the baseband in this paper reduces the complexity of multipath filtering and channel equalization to near O(1).Simulations and experiments indicate that the proposed demodulator maintains performance comparable to conventional demodulation methods,while significantly reducing complexity.
2025年03期 v.44 437-456页 [查看摘要][在线阅读][下载 2206K] [阅读次数：2 ] |[下载次数：1 ] |[引用频次：0 ] -
<正>1 Chinese Journal of Acoustics is the publication of the Acoustical Society of China and the Institute of Acoustics,Chinese Academy of Sciences,to promote the international understanding and collaboration in the field of acoustics.It publishes original works in all branches of acoustics in China.Contributions from invited guests and friends overseas are also solicited.
2025年03期 v.44 457页 [查看摘要][在线阅读][下载 65K] [阅读次数：2 ] |[下载次数：0 ] |[引用频次：0 ] 下载本期数据