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Wyniki wyszukiwania dla: SHALLOW WATER PROPAGATION
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Wyniki wyszukiwania dla: SHALLOW WATER PROPAGATION

  • Theoretical Model of Acoustic Wave Propagation in Shallow Water

    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”...

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  • Shipping Low Frequency Noise and Its Propagation in Shallow Water

    One of the most significant factor influencing acoustical climate of the sea is underwater noise generated by moving ships. If the considered sea area has features of the shallow water, namely the wave frequency fulfils relation f < 10c/h, where c denotes phase speed of sound, and h is depths of the sea, then in certain distance from the wave source specific image of sound pressure distribution in the mean of wave modes appears....

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  • Propagation of Acoustic Disturbances in Shallow Sea

    Publikacja

    - Rok 2013

    Propagation of acoustic waves in shallow sea differs fundamentally from the same phenomenon occurring in deep sea in view of non-negligible distance from the sea bottom in the first case, where presence of two regions limiting the water layer results in the acoustic pressure distribution induced by a harmonic source has an interferential nature as a result of multi-path propagation of the acoustic signal. These interferential properties...

  • Propagation of Ship-Generated Noise in Shallow Sea

    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...

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  • Hydrodynamic Pressure Field of a Ship on Shallow Water

    Publikacja

    - Rok 2013

    Results of calculations of the hydrodynamic pressure field around the ship were obtained by application of the boundary element method. Hydrodynamic field was calculated for a Polish Navy’s tugboat and transport ship using a program called SHiPP and compared with measurements of the field taken on river near Swinoujscie for two identical tugs H-4 and H-10. Next, a series of HPF calculations was carried out on planes situated at...

  • Shallow Water Experiment of OFDM Underwater Acoustic Communications

    The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being...

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  • Balance errors in numerical solutions of shallow water equations

    Publikacja

    The analysis of the conservative properties of the shallow water equations is presented in the paper. The work focuses on the consistency of numerical solution of these equations with the conservation laws of mass and momentum. The investigations involve two different conservative forms which are solved by an implicit box scheme. The theoretical analysis supported by numerical experiments is carried out for rectangular channel...

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  • Assessment of ship squat in shallow water using CFD

    Publikacja
    • J. Jachowski

    - Rok 2007

    Referat zawiera wstęp do problemu modelowania efektów wody ograniczonej przy użyciu komercyjnego programu Fluent opartego na metodzie elementów skończonych.

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  • Assessment of ship squat in shallow water using CFD

    Publikacja

    Artykuł zawiera wstęp do problemu modelowania efektów wody ograniczonej przy użyciu komercyjnego programu Fluent opartego na metodzie elementów skończonych.

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  • Tracking of the broadband source of the underwater noise in the very shallow water conditions

    Publikacja

    The paper contains the result s, both theoretical and experimental , connected with the tracking of the underwater noise source as small ships, pontoon , diver and so on. The pro blem of security in the shallow water area is the challenge for underwater acousticians. In this paper there is take n into account the detection of the sources that move on the surface of the sea or underwater in shallow...

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