Effective roughness on the sea surface for determining variability characteristics of reflected sound waves

Tsukui, Tomoya; Hirata, Shinnosuke; Hachiya, Hiroyuki

doi:10.35848/1347-4065/ac6b80

Cited by 5 publications

(5 citation statements)

References 25 publications

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“…Low frequency ultrasound is generally used in ocean acoustics, to cope with the attenuation that occurs in the water. [14][15][16][17][18] The focus has generally been on the echoes obtained from the swim bladders of fish, because 90% of the echoes from fish when using low frequency ultrasound come from the swim bladder. 19) Megahertz-band ultrasound has been used for high-resolution measurements in other areas of research, such as nondestructive evaluation [20][21][22] and biomedical ultrasound applications.…”

Section: Introductionmentioning

confidence: 99%

Detection of fish passing through a narrow path using reflected and transmitted ultrasonic waves

Miyamoto

Doi

Mizutani

et al. 2023

Jpn. J. Appl. Phys.

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The properties of echoes and transmitted waves from a fish body, in megahertz bands, were investigated to construct a fish detection method in a narrow path by a simple measurement structure using a pair of transducers. Experiments were performed in a water tank using dead Japanese jack mackerel (Trachurus japonicus). From the echoes, the outlines of fish could be observed. High amplitudes of echoes from the swim bladder and fins were observed, while relatively low amplitudes of echoes were observed from other body parts, e.g., the head, body surface, and vertebral columns. From the transmitted waves, decreased amplitudes and times-of-flight in waves transmitted from the fish body were observed. The fish could be detected using ultrasound, in megahertz bands, and the combined use of the echo and transmitted waves could increase the information obtained about fish compared with the use of echoes only.

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Section: Introductionmentioning

confidence: 99%

Detection of fish passing through a narrow path using reflected and transmitted ultrasonic waves

Miyamoto

Doi

Mizutani

et al. 2023

Jpn. J. Appl. Phys.

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“…In the theoretical study of underwater acoustic cladding, numerous methods to calculate its acoustic performance are available, each demonstrating its own characteristics and applicable acoustic structure types. These methods mainly include the transfer matrix method (TMM) (Chahr-Eddine and Yassine, 2014; Lee et al, 2021b), multiple scattering method (MSM) (Li et al, 2006), plane-wave expansion (PWE) (Ponge et al, 2017), finite-difference time-domain (FDTD) (Grinenko et al, 2012;Tsukui et al, 2022), concentrated mass method (CMM) (Bambill et al, 2004), finite element method (FEM) (Hammad et al, 2021;Jiang et al, 2023), and Jacobi -Ritz method (Li et al, 2019b;Pang et al, 2023). The advantages and weaknesses of various typical calculation methods for readers to consider are summarized in Table 1.…”

Section: Calculation and Testing Methods For Underwater Acousticsmentioning

confidence: 99%

Review of Underwater Anechoic Coating Technology Under Hydrostatic Pressure

Jia,

Jin,

2024

J. Marine. Sci. Appl.

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The underwater anechoic coating technology, which considers pressure resistance and low-frequency broadband sound absorption, has become a research hotspot in underwater acoustics and has received wide attention to address the increasingly advanced low-frequency sonar detection technology and adapt to the working environment of underwater vehicles in deep submergence. One the one hand, controlling low-frequency sound waves in water is more challenging than in air. On the other hand, in addition to initiating structural deformation, hydrostatic pressure also changes material parameters, both of which have a major effect on the sound absorption performance of the anechoic coating. Therefore, resolving the pressure resistance and acoustic performance of underwater acoustic coatings is difficult. Particularly, a bottleneck problem that must be addressed in this field is the acoustic structure design with low-frequency broadband sound absorption under high hydrostatic pressure. Based on the influence of hydrostatic pressure on underwater anechoic coatings, the research status of underwater acoustic structures under hydrostatic pressure from the aspects of sound absorption mechanisms, analysis methods, and structural designs is reviewed in this paper. Finally, the challenges and research trends encountered by underwater anechoic coating technology under hydrostatic pressure are summarized, providing a reference for the design and research of low-frequency broadband anechoic coating.

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“…We have developed a method for analyzing moving sound sources and receivers using the finite difference-time domain (FDTD) method. [6][7][8][9][10][11][12][13][14][15][16] We have previously implemented moving sound sources and receivers with omni-directional directivity in the two-dimensional (2D) 17,18) and threedimensional FDTD methods. 19) Furthermore, we have implemented movings sound sources and receiver with simple directivity, such as dipole and cardioid, in two-dimensions 20) and three-dimensions.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional finite difference-time domain simulation of moving multipole sources

Tsuchiya

2024

Jpn. J. Appl. Phys.

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In this paper, the implementation of a moving multipole sound source in the two-dimensional finite difference-time domain method is described. The fundamental solution of the moving multipole source is theoretically derived by spatial differentiation of the fundamental solution of a moving monopole source in the two-dimensional field. It was found theoretically that the directivity of a moving multipole source depends on the velocity and order of spatial differentiation. Numerical experiments were performed on the two-dimensional sound field for moving multipole sources, and the results showed that the effect of the moving velocity on the amplitude of the multipole source is increased with the order of spatial differentiation. It was also found that the higher the order of spatial differentiation, the sharper the directivity in the moving direction and the larger the front-to-back ratio of the directivity. The present method can be accurately applied to the moving multipole sound sources.

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Effective roughness on the sea surface for determining variability characteristics of reflected sound waves

Cited by 5 publications

References 25 publications

Detection of fish passing through a narrow path using reflected and transmitted ultrasonic waves

Detection of fish passing through a narrow path using reflected and transmitted ultrasonic waves

Review of Underwater Anechoic Coating Technology Under Hydrostatic Pressure

Two-dimensional finite difference-time domain simulation of moving multipole sources

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