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Wyszukujesz frazę "Ramis, J." wg kryterium: Autor

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    Wyświetlanie 1-4 z 4
    Tytuł:
    Evaluation of two alternative procedures for measuring airflow resistance of sound absorbing materials
    Autorzy:
    del Rey, R.
    Alba, J.
    Arenas, J. P.
    Ramis, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/176777.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    material characterization
    airflow resistance
    sound absorbing materials
    eco-friendly material
    Opis:
    It is well known that sound absorption and sound transmission properties of open porous materials are highly dependent on their airflow resistance values. Low values of airflow resistance indicate little resistance for air streaming through the porous material and high values are a sign that most of the pores inside the material are closed. The laboratory procedures for measuring airflow resistance have been stan- dardized by several organizations, including ISO and ASTM for both alternate flow and continuous flow. However, practical implementation of these standardized methods could be both complex and expensive. In this work, two indirect alternative measurement procedures were compared against the alternate flow standardized technique. The techniques were tested using three families of eco-friendly sound absorbent materials: recycled polyurethane foams, coconut natural fibres, and recycled polyester fibres. It is found that the values of airflow resistance measured using both alternative methods are very similar. There is also a good correlation between the values obtained through alternative and standardized methods.
    Źródło:
    Archives of Acoustics; 2013, 38, 4; 547-554
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Inverse Method to Obtain Porosity, Fibre Diameter and Density of Fibrous Sound Absorbing Materials
    Autorzy:
    Alba, J.
    del Rey, R.
    Ramis, J.
    Arenas, J. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/177007.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sound absorption
    fibrous materials
    porous material
    material characterization
    Opis:
    Characterization of sound absorbing materials is essential to predict its acoustic behaviour. The most commonly used models to do so consider the flow resistivity, porosity, and average fibre diameter as parameters to determine the acoustic impedance and sound absorbing coefficient. Besides direct experimental techniques, numerical approaches appear to be an alternative to estimate the material's parameters. In this work an inverse numerical method to obtain some parameters of a fibrous material is presented. Using measurements of the normal incidence sound absorption coefficient and then using the model proposed by Voronina, subsequent application of basic minimization techniques allows one to obtain the porosity, average fibre diameter and density of a sound absorbing material. The numerical results agree fairly well with the experimental data.
    Źródło:
    Archives of Acoustics; 2011, 36, 3; 561-574
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Evaluation of the Vibration Reduction Index for Structural Joints
    Autorzy:
    Ramis, J.
    Segovia, E.
    Alba, J.
    Carbajo, J.
    Godinho, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/177736.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    finite element model
    vibration reduction
    structural joints
    Opis:
    The present paper addresses the analysis of structural vibration transmission in the presence of struc- tural joints. The problem is tackled from a numerical point of view, analyzing some scenarios by using finite element models. The numerical results obtained making use of this process are then compared with those evaluated using the EN 12354 standard vibration reduction index concept. It is shown that, even for the simplest cases, the behavior of a structural joint is complex and evidences the frequency dependence. Comparison with results obtained by empirical formulas reveals that those of the standards cannot accurately reproduce the expected behavior, and thus indicate that alternative complementary calculation procedures are required. A simple methodology to estimate the difference between numerical and standard predictions is here proposed allowing the calculation of an adaptation term that makes both approaches converge. This term was found to be solution-dependent, and thus should be evaluated for each structure.
    Źródło:
    Archives of Acoustics; 2012, 37, 2; 189-197
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Experimental Approach to Vibro-Acoustic Study of Beam-Type Structures
    Autorzy:
    Torres-Romero, J.
    Cardenas, W.
    Carbajo, J.
    Segovia Eulogio, E. G.
    Ramis-Soriano, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/178014.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    beam
    modal shape
    modal analysis
    MLS
    Maximum Length Sequence
    bending wave propagation velocity
    Opis:
    In this paper an alternative procedure to vibro-acoustics study of beam-type structures is presented. With this procedure, it is possible to determine the resonant modes, the bending wave propagation velocity through the study of the radiated acoustic field and their temporal evolution in the frequency range selected. As regards the purely experimental aspect, it is worth noting that the exciter device is an actuator similar to is the one employed in distributed modes loudspeakers; the test signal used is a pseudo random sequence, in particular, an MLS (Maximum Length Sequence), facilitates post processing. The study case was applied to two beam-type structures made of a sandstone material called Bateig. The experimental results of the modal response and the bending propagation velocity are compared with well-established analytical solution: Euler-Bernoulli and Timoshenko models, and numerical models: Finite Element Method – FEM, showing a good agreement.
    Źródło:
    Archives of Acoustics; 2018, 43, 2; 283-295
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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