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Wyszukujesz frazę "water layer" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Theoretical model of acoustic wave propagation in shallow water
Autorzy:
Kozaczka, E.
Grelowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/258460.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
shallow water acoustics
propagation of acoustic waves in water layer
Opis:
The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.
Źródło:
Polish Maritime Research; 2017, 2; 48-55
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Propagation of ship-generated noise in shallow sea
Autorzy:
Kozaczka, E.
Grelowska, G.
Powiązania:
https://bibliotekanauki.pl/articles/259166.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
shallow water acoustics
propagation of acoustic waves in water layer
wave modes in shallow sea
underwater noise produced by ship
Opis:
Contamination of sea environment by noise and any energy radiated to water constitutes today a problem to which more and more attention is paid, in view, a.o., of consequences of an impact of these factors onto marine fauna. European Union has introduced a directive by which EU countries are made responsible to undertake efforts aimed at reaching a good envirenmental status of European seas by 2020. A main source of underwater noise is sea transport of any kind. Propagation of underwater acoustic disturbances in the Baltic Sea highly differs from the course of the phenomenon in a deep sea. Model of spherical propagation cannot be applied to this case in view of water environment limitation by seabed and free water surface, i.e. a reduction of the problem to wave propagation in a water layer of the depth comparable with acoustic wave length. This paper is aimed at demonstration of possible assessment of range of acoustic disturbances generated by a ship sailing in shallow sea, by using a method described in the work [13]. The research was made on the basis of results of own measurements of underwater noise produced by ships in the Gdansk Bay area. An important factor which decIdes on a range of underwater disturbances is a kind of seabed sediments. In this paper there are presented results of numerical investigations based on real data dealing with noise produced by a selected floating unit (ship) for selected characteristic spectral components. The simulations were conducted for the shallow sea model of definite physical parameters such as acoustic wave propagation velocity, geometrical dimensions (water depth) and seabed acoustic parameters as well.
Źródło:
Polish Maritime Research; 2018, 2; 37-46
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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