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Wyszukujesz frazę "underwater sound" wg kryterium: Temat

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    Wyświetlanie 1-4 z 4
    Tytuł:
    Statistical Optimization of Underwater Lower-Frequency Sound Insulation for Locally Resonant Sonic Material Using Genetic Algorithm
    Autorzy:
    Yuan, Bo
    Chen, Yong
    Tan, Bilian
    Li, Bo
    Powiązania:
    https://bibliotekanauki.pl/articles/177461.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    underwater acoustic
    sound insulation
    local resonance
    statistical optimization
    global optimum
    Opis:
    The locally resonant sonic material (LRSM) is an artificial metamaterial that can block underwater sound. The low-frequency insulation performance of LRSM can be enhanced by coupling local resonance and Bragg scattering effects. However, such method is hard to be experimentally proven as the Best optimizing method. Hence, this paper proposes a statistical optimization method, which first finds a group of optimal solutions of an object function by utilizing genetic algorithm multiple times, and then analyzes the distribution of the fitness and the Euclidean distance of the obtained solutions, in order to verify whether the result is the global optimum. By using this method, we obtain the global optimal solution of the low-frequency insulation of LRSM. By varying parameters of the optimum, it can be found that the optimized insulation performance of the LRSM is contributed by the coupling of local resonance with Bragg scattering effect, as well as a distinct impedance mismatch between the matrix of LRSM and the surrounding water. This indicates coupling different effects with impedance mismatches is the Best method to enhance the low-frequency insulation performance of LRSM.
    Źródło:
    Archives of Acoustics; 2019, 44, 2; 365-374
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Underwater Noise Generated by a Small Ship in the Shallow Sea
    Autorzy:
    Grelowska, G.
    Kozaczka, E.
    Kozaczka, S.
    Szymczak, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/177360.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal processing
    sound propagation
    underwater ship noise
    propagation in the shallow sea
    Opis:
    Study of the sea noise has been a subject of interest for many years. The first works in this scope were published at the turn of the twentieth century by Knudsen (Knudsen et al., 1948) and G. Wenz (Wenz, 1962). Disturbances called “shipping noise” are one of the important components of the sea noise. In this work the results of an experimental research of underwater noise produced by a small ship of a classic propulsion are presented. A linear receiving antenna composed of two orthogonal components was used in the investigation. Identification of the main sources of acoustic waves related with the ship was achieved. In addition, the intensity of the wave was measured. The research was performed in conditions of the shallow sea.
    Źródło:
    Archives of Acoustics; 2013, 38, 3; 351-356
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices
    Autorzy:
    Yuan, B.
    Chen, Y.
    Jiang, M.
    Tang, S.
    He, M.
    Tu, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177103.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    locally resonant phononic crystals
    effective speed of sound
    coupling band gaps
    underwater acoustic materials
    Opis:
    Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.
    Źródło:
    Archives of Acoustics; 2017, 42, 4; 725-733
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design Sensitivity Studies on a Hydroacoustic Projector Using an Experimentally Validated Easy-to-Build Model
    Autorzy:
    Sreejith, Vattaparambil Sreedharan
    Tiwari, Nachiketa
    Powiązania:
    https://bibliotekanauki.pl/articles/2141678.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    low frequency sound source
    underwater transducer
    fluid power
    hydro-electro-mechano-acoustic analogy
    hydraulic valve
    piston
    cylinder
    Opis:
    Hydroacoustic projectors are useful for generating low frequency sounds in water. Existing works on hydroacoustic projectors require two significant enhancements, especially for designers. First, we need to understand the influence of important projector design parameters on its performance. Such insights can be very useful in developing a compact and efficient projector. Second, there is a need for an integrated model of the projector based on easily available and user-friendly numerical tools which do not require development of complex customised mathematical analogs of projector components. The present work addresses both such needs. Towards these goals, an experimentally validated, easy-to-build projector model was developed and used to conduct design sensitivity studies. We show that reductions in pipe compliance and air content in oil, and an increase in orifice discharge coefficient can yield remarkable improvements in projector’s SPL. We also show that reductions in pipe length and cylinder diameter cause moderate improvements in performance in mass and stiffness controlled regions, respectively. In contrast, the projector performance is insensitive to changes in pistonic mass, cylinder length, and diaphragm stiffness. Finally, we report that while pipe compliance and air content in oil can sharply alter system resonance, the effects of changes in pipe length and pistonic mass on it are moderate in nature.
    Źródło:
    Archives of Acoustics; 2022, 47, 1; 113-124
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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