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Wyszukujesz frazę "underwater noise" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Field Study on Underwater Noise Emitted by Small Tourist Boats. Comparison Between the Use of Electric and Combustion Motors
Autorzy:
Yori, Alfio
Powiązania:
https://bibliotekanauki.pl/articles/31339825.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
small boat underwater noise
anthropogenic underwater noise
electric motor boat
underwater noise produced by tourist boats
Opis:
Small boats, possessing outboard engines, are widely used in tourism and mammal watching within marine protected areas. Noise generated by this type of vessels has the capacity to negatively affect marine fauna, especially marine mammals, which use sound throughout all the phases of their lives. These tourism boats used in mammal watching may use different propulsion systems, such as gas, diesel or electric engines. To characterize underwater noise emitted by this type of vessels becomes relevant not only when assessing the acoustic impact produced by these different propulsion systems over the marine fauna living inside these protected marine areas, but also when determining which one produces the least impact. A comparative study of underwater noise emissions coming from small touristic boats was made in this study. Boats were similar in capacity and functions, although possessing different propulsion systems. Measurements were made on two boats with a 50 Hp internal combustion engine and one 5 Hp electric boat. These boats were selected to be studied because they have practically the same size, possess the same passenger-capacity and are used to make similar jobs and routes inside the protected area where they are operated. The electric boat showed a considerable decrease in underwater noise emissions, especially in low frequencies. This boat will produce a lower accumulated exposition of the fauna to the noise or will allow a closer approach to the observed species. Measurements were made between September 2018 and January 2020
Źródło:
Archives of Acoustics; 2023, 48, 3; 347-358
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Spatial Noise Correlation on Bearing Accuracy in DIFAR Systems
Autorzy:
Rudnicki, Mariusz
Marszal, Jacek
Salamon, Roman
Powiązania:
https://bibliotekanauki.pl/articles/1953524.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
underwater noise
noise correlation
DIFAR sonobuoys
bearing accuracy
Opis:
DIFAR type underwater passive systems are one of the more commonly used tools for detecting submarines. At the design stage, which usually uses computer simulations, it is necessary to generate acoustic noise of the sea. It has been shown that correlating noise significantly reduces these errors compared to the assumption that noise is uncorrelated. In addition, bearing errors have been shown to be the same in systems with a commonly used antenna containing five hydrophones, as in a system without a central hydrophone, which may be useful in some DIFAR system design solutions.
Źródło:
Archives of Acoustics; 2020, 45, 4; 709-720
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impulse Excitation in a Watertight Steel Circular Cylindrical Shell and Influence of Structural Configuration on Underwater Radiated Noise
Autorzy:
Wu, Chen-I
Too, Gee-Pinn
Wu, Bo-Hsien
Powiązania:
https://bibliotekanauki.pl/articles/31339791.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
impulse excitation
influence of structural configuration
FEM analysis
underwater noise radiation characteristics
Opis:
This study used experimental measurements and the finite-element method (FEM) simulations to investigate transient underwater radiated noise induced by the impulse excitation of water surrounding a watertight steel-structured circular cylindrical shell submerged in the 176 × 8 × 4 m towing tank. The excitation was caused by dropping an iron block onto a structural bracket in the shell to generate structural vibration. The experimental results were found to be consistent with the FEM results, with the difference between the experimental and simulated sound pressure levels being less than 3 dB. Moreover, it was determined that the structural vibration also generated airborne noise in the cylindrical shell, but this contributed much less than the impulse excitation to the induction of underwater radiated noise. Finally, analysis of the sound field of the underwater noise radiation showed that it was influenced by the wall thickness of the watertight steel cylindrical shell and that of the reinforced bracket seat structure. In particular, the structural reinforcement position proved to be the diffusion breakpoint of the underwater sound radiation. This demonstrates that compared with the studied structure, a thicker and more complex reinforced structure will transmit less or incomplete sound radiation into water.
Źródło:
Archives of Acoustics; 2023, 48, 4; 509-521
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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