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The Influential Factors and Prediction of Kuroshio Extension Front on Acoustic Propagation-Tracked

Xu Weishuai, Zhang Lei, Wang Hua

Archives of Acoustics

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2024

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Vol. 49, nr 1

95--106

EN

The Kuroshio Extension front (KEF) considerably influences the underwater acoustic environment; however, a knowledge gap persists regarding the acoustic predictions under the ocean front environment. This study utilized the high-resolution ocean reanalysis data (JCOPE2M, 1993–2022) to assess the impact of the KEF on the underwater acoustic environment. Oceanographic factors were extracted from the database using the Douglas-Peucker algorithm, and acoustic propagation characteristics were obtained using the Bellhop raytracing model. This study employed a backpropagation neural network to predict the acoustic propagation affected by the KEF. The depth of the acoustic channel axis and the vertical gradient of the transition layer of sound speed were identified as the fundamental factors influencing the first area of convergence, with correlations between the former and the distance of the first convergence zone ranging from 0.52 to 0.82, and that for the latter ranging from −0.42 to −0.7. The proposed method demonstrated efficacy in forecasting first convergence zone distances, predicting distances with less than 3 km error in >90% of cases and less than 1 km error in 68.61% of cases. Thus, this study provides a valuable predictive tool for studying underwater acoustic propagation in ocean front environments and informs further research.

2

The Effect of Cold Eddy on Acoustic Propagation (Case Study : Eddy in the Persian Gulf)

Mahpeykar Omid, Ashtari Larki Amir, Akbari Nasab Mohammad

Archives of Acoustics

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2022

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Vol. 47, No. 3

413--423

EN

It is essential for oceanographers to study the effects of marine phenomena such as currents, surface mixed layer, eddies, internal waves, and other ocean features on acoustic propagation, as most marine measurement equipment operates on this basis, like sonar. The eddy impact on acoustic transmission in the marine environment is very significant because changes in temperature and salinity disrupt the sound speed due to the presence of eddy, thus the acoustic propagation in the sea. Although cold eddies are in the Persian Gulf widely, one eddy is selected to study their impacts on acoustic propagation because they have similar properties in terms of temperature and salinity. In this research, after identifying eddies in the Persian Gulf automatically, the effect of a cold eddy on acoustic propagation was investigated at different depths using the BELLHOP model. Most eddies are cyclonic with 5–10 km of radius based on algorithm outputs. Studies on the lifespan of eddies showed that the occurrence of cyclonic eddies with a lifespan of more than three days is more than anticyclonic ones. Examination of the eddy effect on acoustic propagation showed that the transmission loss (TL) during the progress of the acoustic wave across the eddy increases with increasing the depth of the sound source. Also, the presence of cold eddy compared to the conditions it does not exist increases the transmission loss. The study of three-dimensional acoustic propagation also confirmed the obtained results in two-dimensional mode and clearly showed the role of cold eddy in increasing the TL.

3

Numerical modeling of uncertainty in acoustic propagation via generalized Polynomial Chaos

Dammak Khalil, Koubaa Sana, Elhami Abdelkhalak, Walha Lassaad, Haddar Mohamed

Journal of Theoretical and Applied Mechanics

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2019

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Vol. 57 nr 1

3--15

EN

This work aims at increasing the performance prediction for acoustic propagation systems that will operate in the presence of the inevitable parameters uncertainty. In the present contribution, the finite element method is applied to solve an acoustic problem described by the Helmholz equation when the geometric and material properties present uncertainty. The influence of the uncertainty of physical parameters on the pressure field is discussed. The results using the polynomial chaos expansion method are compared with Monte Carlo simulations. It is show that uncertainty levels in the input data could result in large variability in the calculated pressure field in the domain.

4

Zastosowanie zjawiska propagacji akustycznej fali powierzchniowej w sensorach gazu

Urbańczyk M., Opilski A., Jakubik W.

Elektronika : konstrukcje, technologie, zastosowania

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2001

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Vol. 42, nr 3

45-46

PL

Przedstawiono możliwości wykorzystania zjawiska propagacji akustycznej fali powierzchniowej do detekcji gazów. Oddziaływanie określonych zewnętrznych wielkości fizycznych na ośrodek propagacji, w tym na samą powierzchnię, wpływa na warunki graniczne zagadnienia propagacji fali powierzchniowej. W przypadku czujników gazu zaburzenie propagacji (prędkości i tłumienia) zachodzi wskutek zmian właściwości mechanicznych i/lub elektrycznych cienkiej warstwy sensorowej naniesionej na powierzchnię falowodu. Wyniki rozważań teoretycznych potwierdzono badaniami eksperymentalnymi.

EN

Presents theoretical possibilities of application of a SAW in gas sensors. Interaction of external physical quantity on propagation medium, including the surface, can affect SAW propagation. In gas sensors disturbance of SAW propagation is results from change of the mechanical as well as electrical properties of a thin active sensor layer placed on a piezoelectric surface. The experimental results also have been presented.