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Ultrasound beam shift induced by short-beaked common dolphin’s(Delphinus delphis) tissues as an attenuating gradient material

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Science China(Physics,Mechanics & Astronomy) 2021年第10期64卷 103-112页

作者： Chuang Zhang Zhongchang Song Steven WThornton Erqian Dong Peizheng Cao Feng Ye Xianyan Wang Yu Zhang Key Laboratory of Undenvater Acoustic Communication and Marine Information Technology of the Ministry of Education College of Ocean and Earth SciencesXiamen UniversityXiamen 361005China State Key Laboratory of Marine Environmental Science College of the Environment and EcologyXiamen UniversityXiamen 361005China Department of Biology and Marine Biology University of North Carolina WilmingtonWilmingtonNC 28403USA Affiliated Zhongshan Hospital of Xiamen University Xiamen 361005China Third Institute of Oceanography Ministry of Natural ResourcesXiamen 361005China State Key Laboratory of Marine Environmental Science College of Ocean and Earth SciencesXiamen UniversityXiamen 361005China

To understand sound propagation and beam formation, the physical properties of soft tissues from the biosonar system of odontocetes should be explored. Based on the acoustic impedance distributions of biosonar systems, these processes have been examined via numerical simulations. In this study, the images of a short-beaked common dolphin(Delphinus delphis) were obtained via computed tomography. Then, the dolphin was dissected to extract tissue samples for additional examination. In addition to the speed of sound and density measurements, the acoustic attenuation coefficients of the biosonar system in the forehead were tested. The results revealed that the inner layer of the forehead was characterized using low sound speed, low density, and high attenuation. Acoustic fields and beam patterns were then evaluated by setting acoustic attenuation coefficients at different levels. Sounds propagating along the low-attenuation path had a lesser reduction in amplitude. beam directivities in near and far fields suggested that changes in attenuation distribution would cause beam patterns to shift. These results indicated the complexity of a dolphin’s sonar emission system and helped improve our understanding of sound energy attenuation via studies on the forehead of odontocetes.

关键词： short-beaked common dolphin acoustic attenuation beam pattern computed tomography

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Optimized simulated annealing algorithm for thinning and weighting large planar arrays

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第4期11卷 261-269页

作者： Peng CHEN Bin-jian SHEN Li-sheng ZHOU Yao-wu CHEN Institute of Advanced Digital Technologies and lnstrumentation Zhejiang University Hangzhou 310027 China Hangzhou Applied Acoustics Research Institute Hangzhou 310012 China

This paper proposes an optimized simulated annealing(SA) algorithm for thinning and weighting large planar arrays in 3D underwater sonar imaging *** optimized algorithm has been developed for use in designing a 2D planar array(a rectangular grid with a circular boundary) with a fixed side-lobe peak and a fixed current taper ratio under a narrow-band *** extensions of the SA algorithm and the procedure for the optimized SA algorithm are *** examples of planar arrays are used to assess the efficiency of the optimized *** proposed method achieves a similar beam pattern performance with fewer active transducers and faster convergence ability than previous SA algorithms.

关键词： Simulated annealing(SA) Sparse planar arrays 3D underwater sonar imaging beam pattern Optimization

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