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Wyszukujesz frazę "coefficient of sound absorption" wg kryterium: Temat

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    Wyświetlanie 1-3 z 3
    Tytuł:
    Method of Determining the Sound Absorbing Coefficient of Materials within the Frequency Range of 5 000–50 000 Hz in a Test Chamber of a Volume of about 2 m3
    Autorzy:
    Mikulski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/177184.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ultrasonic noise
    sound absorption coefficient of materials
    Opis:
    Sound absorption coefficient is a commonly used parameter to characterize the acoustic properties of sound absorbing materials. It is defined within the frequency range of 100-5 000 Hz. In the industrial conditions, many appliances radiating acoustic energy of the frequency range of above 5000 Hz are used and at the same time it is known that a noise within the frequency range of 5 000-50 000 Hz can have a harmful effect on people,hence there is a need to define the coefficient in this frequency range. The article presents a proposal for a method of measurement of the sound absorption coefficient of materials in the frequency range from 5 000 Hz to 50 000 Hz. This method is a modification of the reverberation method with the use of interrupted noise.
    Źródło:
    Archives of Acoustics; 2013, 38, 2; 177-183
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sensitivity Analysis of Acoustic Field Parameters on a Change of Boundary Conditions in a Room
    Autorzy:
    Suder-Dębska, K.
    Czajka, I.
    Czechowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177639.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sensitivity analysis
    acoustic parameter
    geometrical method
    sound absorption coefficient
    noise of power machines
    Opis:
    The area of environmental protection concern minimises the impact that technical objects have on the environment. Usually the most effective way of protecting the environment is to influence the source of the problem. For this reason studies are conducted to modify the construction of machines, power machines in particular, so as to minimise their impact on the environment. In the case of environmental protection from noise it is most convenient to carry out measurements in an anechoic chamber. Unfortunately, this is possible only in very limited circumstances. In all other cases measurements are performed using an engineering method or the survey method, both of which are described in the standards and by taking into account the so-called environmental corrections. The obtained results are burdened with greater error than those of measurements in an anechoic chamber. Therefore, it would seem advantageous to develop a method of obtaining similar and reliable results as those in an anechoic chamber, but in a reverberant field. The authors decided to use numerical modelling for this purpose. The main objective of this work is a comprehensive analysis of the numerical model of a laboratory designed for acoustic tests of selected power machines. The geometry of a room comprising an area of analysis is easy to design. The main difficulty in modelling the phenomena occurring in the analysed area can be the lack of knowing the boundary conditions. Therefore, the authors made an attempt to analyse the sensitivity of various acoustic parameters in a room in order to change these boundary conditions depending on the sound absorption coefficient.
    Źródło:
    Archives of Acoustics; 2014, 39, 3; 343-350
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound Absorption Behavior of Polyurethane Foam Composites with Different Ethylene Propylene Diene Monomer Particles
    Autorzy:
    Zhu, W.
    Chen, S.
    Wang, Y.
    Zhu, T.
    Jiang, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/178030.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    polyurethane foam composites
    EPDM
    Ethylene Propylene Diene Monomer
    contents of EPDM
    hardness of EPDM
    sound absorption coefficient
    Opis:
    Considering the environmental pollution caused by waste rubber, some measures should be taken to improve the utilization rate of waste rubber. In this study, the effect of Ethylene Propylene Diene Monomer (EPDM) particles in the polyurethane (PU) foams on sound absorption behavior is investigated for improving sound environment within vehicles and reducing the environment pollution. EPDM particles of different contents and hardness are used as fillers for producing foams with different pore morphologies and sound absorption properties. The results show that adding EPDM to foam would produce smaller pores, higher density and bigger air-flow resistivity. Simultaneously, there are better sound absorption properties of the PU foam composites in the medium frequency region, and the better value can be obtained at the lower frequency with the content of EPDM increasing. The hardness of EPDM also shows better influence on sound absorption properties, especially in the medium frequency region. It means the foam pore morphologies have influence on sound absorption properties.
    Źródło:
    Archives of Acoustics; 2018, 43, 3; 403-411
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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