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Wyświetlanie 1-6 z 6
Tytuł:
Theoretical and Experimental Determination of the Sound-Absorbing Property Class of Acoustic Barriers
Autorzy:
Turkiewicz, J.
Wszołek, G.
Powiązania:
https://bibliotekanauki.pl/articles/1359889.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.55.Ev
43.50.Gf
Opis:
The currently applicable PN-EN 1793-1 standard concerning anti-noise devices on roads recommends for acoustic barriers built along traffic routes to have panels characterized by good sound-absorbing properties. The sound-absorbing properties of these panels (wall elements) are to be specified by giving the values of the single-number sound absorption evaluation index $DL_α$ and the absorption property class determined in accordance with the PN-EN 1793-3:2001 standard. Continuous regular acoustic studies of new materials heretofore not used in anti-noise protections are conducted in the Department of Mechanics and Vibroacoustics at AGH. This paper presents the findings of research that started with different porous materials physical absorption coefficient tests. The purpose of these preliminary tests was to pick out materials with best sound-absorbing properties from the group of acoustically tested materials. The chosen materials could be used as a sound-absorbing lining on panels (wall elements) used in the design of acoustic barriers. On the basis of the obtained results, two materials with values of the average physical sound absorption coefficient higher than 0.5 ($α_{favg}$>0.5) were picked out for further acoustic tests. This paper presents results of studies that had the final effect consisting in determining the values of the single-number sound absorption evaluation index $DL_α$ and the absorption property class for two prototype panels of an acoustic barrier the sound-absorbing lining of which was made up of materials chosen after preliminary acoustic studies. The determination of sound-absorbing property classes was carried out both theoretically and experimentally. In order to be possible to reduce the costs of acoustic tests in the future, particularly of new materials in regard to which there is a margin of uncertainty of whether their sound-absorbing properties meet expectations, the authors determined sound-absorbing property classes of acoustic barriers theoretically and then compared theoretical results with the results of experimental tests.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-127-A-130
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modifications of Computational Formulae of Decibel Algebra Applied in Acoustics
Autorzy:
Batko, W.
Powiązania:
https://bibliotekanauki.pl/articles/1504169.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.50.Rq
43.50.Sr
43.50.Gf
Opis:
The analysis of description rules of acoustic effects in decibel algebra was performed in the presented paper. The attention was drawn to the incompatibility between mappings examined on the decibel values set and axioms of the real numbers theory. The consequences of this fact as well as the needs of the necessary modifications of relations describing a cooperation of sound levels from various sources (expressed by adding, subtracting or multiplying) were discussed. The necessary corrections were proposed. The analysis of differences was performed in relation to generally applied rules of processing the decibel measurement results in acoustic examinations.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 909-912
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of External Acoustic Noise οn the Operation of an Open Photoacoustic Helmholtz Cell
Autorzy:
Starecki, T.
Powiązania:
https://bibliotekanauki.pl/articles/1811564.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.50.Gf
43.38.Zp
43.58.Kr
Opis:
One of the most important problems in the design of open photoacoustic cells is appropriate attenuation of the external acoustic noise, because in the case of weak photoacoustic signals even relatively low level of such an acoustic noise can severely limit sensitivity of the setup. It is important that the mentioned filtering is not limited to the frequencies close to the light modulation frequency, but performed in the possibly widest band width, because although it is usually considered that setup sensitivity depends directly on the parameters of the final narrowband filtering and/or synchronous detection, it should be noticed that it can be also seriously affected by saturation of the signal amplifiers being overdriven by the signal components resulting from the mentioned acoustic noise. The paper describes how influence of the external acoustic noise on the operation of an open photoacoustic Helmholtz cell depends on mechanical dimensions of the cell. The results show that appropriate selection of the dimensions results in noticeable improvement of the external acoustic noise attenuation.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-199-A-204
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Passive and Active Methods for Minimization of Sound Radiation by Vibrating Clamped Plate
Autorzy:
Kozupa, M.
Wiciak, J.
Powiązania:
https://bibliotekanauki.pl/articles/1504409.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Dx
43.40.Rj
43.40.Vn
43.50.Gf
43.50.Ki
Opis:
The paper is an analytical and experimental study of a smart structure consisting of steel plate with bonded piezoelectric transducers and porous elastomer layer. Active control of sound radiation from a plate clamped at the edge square is examined. Simulations and numerical computation of the experiment are performed in Ansys environment. Calculations of plate vibration and sound radiation under stepped harmonic force are performed. The experimental setup consists of two rooms with the test opening in between. A variety of test cases were studied for three different configurations: steel plate + piezoelectric transducer, steel plate + elastomer layer, steel plate + piezoelectric transducer + elastomer layer. The aim of the paper is to illustrate the possibilities of using piezoelectric materials as an active control with elastomer layers as passive methods in one structure to improve the transmission loss.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1013-1017
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound Wave Diffraction at the Edge of a Sound Barrier
Autorzy:
Piechowicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1504424.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.El
43.20.Fn
43.50.Gf
43.50.Yw
43.60.Ek
43.55.Rg
Opis:
The diffraction phenomenon is described by the Huygens-Fresnel principle. The review of physical laws ruling the bending of sound waves at the edge of the screen allows the effective selection of both acoustical and geometrical parameters of the screen. Sound wave diffraction theories have been developed on the basis of wave optics, when wavelength is small in comparison to the size of the obstacles, which can be also used in acoustics with the same assumptions about geometry of the system. Diffraction can be seen as a result of the interference of waves reaching the point of observation in accordance with the laws of geometrical optics and wave disturbances arising as a result of interaction with the edge of an obstacle. The paper describes a test method using maximum length sequences for determining the intrinsic characteristics of sound diffraction in situ during testing of roadside noise barriers. A scale model experiment has been performed in an anechoic room. Also, a real noise reducing device was tested in free field conditions.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1040-1045
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound Diffraction Over Noise Barriers with Added Devices Installed on the Top Edge
Autorzy:
Piechowicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1402178.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.El
43.20.Fn
43.50.Gf
43.50.Yw
43.60.Ek
43.55.Rg
Opis:
Airborne sound insulation index of the noise barrier panel and the sound absorption coefficient of the barrier surface are the acoustic parameters that are usually determined in specialized laboratories, however they can be also determined in situ. Acoustic characteristics of a barrier include also the diffraction index difference determined from comparison of barriers with plain top edges and barriers with added devices installed on the top edge. The index is determined from the impulse response values determined for the acoustic wave propagation path from the sound source to a set of properly distributed measurement points. By means of the same method, one can also determine the difference in a barrier's acoustic effectiveness between the plain top barrier structure and its version with added devices mounted on the top. The paper presents measurement results for three types of added devices mounted on the top edge of the barrier. The diffraction index differences have been determined for each added device type and the acoustic effectiveness for each device has been compared with the plain top edge acoustic barrier.
Źródło:
Acta Physica Polonica A; 2015, 128, 1A; A-36-A-40
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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