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Wyszukujesz frazę "43.20.Rz" wg kryterium: Temat


Wyświetlanie 1-10 z 10
Tytuł:
Open End Correction for Arbitrary Mode Propagating in a Cylindrical Acoustic Waveguide
Autorzy:
Snakowska, A.
Jurkiewicz, J.
Smolik, D.
Powiązania:
https://bibliotekanauki.pl/articles/1493260.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Rz
43.20.Mv
Opis:
The paper presents a method of theoretical derivation and numerical calculation of the open-end correction coefficient for an arbitrary cut-on mode propagating in acoustic waveguide. Actually, the so-called open-end correction coefficient of acoustic tube, frequently discussed in literature, refers to specific conditions, when the wave heading the outlet is the plane wave. It follows from the fact that the plane wave is a commonly applied approximation when considering phenomena in duct-like devices or systems (tubes, musical instruments, heating or ventilation systems). The aim of the paper is to extend the concept of the open-end correction on the so-called higher Bessel modes, that under some conditions can also propagate in a duct. Theoretical results, forming the basis for numerical calculations, were obtained by considering diffraction at the duct end and applying the Wiener-Hopf factorization method. As a result, the formula for the acoustic field inside the duct was derived. For each Bessel mode present in the incident wave the reflected wave is composed of all cut-on modes of the same circumferential order. Each mode present in the reflected wave is characterized by the complex reflection/coupling coefficient, argument of which describes phase change at the duct end and therefore the open-end correction coefficient can be attributed to each coupled pair of modes.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 736-739
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Impedance of Outlet of a Hard-Walled Unbaffled Cylindrical Duct for Multimode Incident Wave
Autorzy:
Jurkiewicz, J.
Snakowska, A.
Smolik, D.
Powiązania:
https://bibliotekanauki.pl/articles/1504427.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Mv
43.20.Rz
Opis:
In the paper, the specific acoustic impedance of outlet of an unbaffled duct for incident wave composed of one or many circumferential cut-on duct modes has been derived and presented on graphs. When considering the multimode excitation the equal energy per mode principle and random phases have been assumed. Experimentally verified assumption on equal energy per mode allows for quantitative analysis of the sound field and thus provides more physical insight into the in-duct and out-duct phenomena. The assumption of random phase was implemented by means of the Monte Carlo method and so the expected value, the standard deviation and the percentile curves of the impedance were presented. Numerical data obtained according to the derived theoretical formulae for single and multimode incident wave manifest strong modal character and dependence on the modes phases. The assumption of multimode incident wave has brought the theoretical model closer to what is being observed in practice, especially when ducts of large radius, such as heating and air conditioning systems or turbojet engines, are considered.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1061-1067
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modification of the Measurement Setup for Examination of Acoustic Field Distribution Inside Cylindrical Ducts for Axisymmetric Excitation
Autorzy:
Gorazd, Ł.
Jurkiewicz, J.
Raab, S.
Snakowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1400096.pdf
Data publikacji:
2013-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Rz
43.20.Mv
Opis:
The aim of the paper is to present results of examination of the acoustic pressure field inside a model of a cylindrical duct. Measurements of the root mean square acoustic pressure were carried out using a new measurement setup, first in conditions allowing for propagation of the plane wave only, and next - by increasing the excitation frequency - with successive higher modes also taken in account. Two types of hard-walled cylindrical ducts were examined corresponding to mathematical models known as the infinite duct and the semi-infinite duct. A dedicated measurement setup is presented as well as the successive stages of its modification. In order to verify the modified measuring system, the first stage of the research work consisted in excitation of the axisymmetric modes only and assessing the degree of symmetry represented by the measurement data Significant improvement of the compatibility of the obtained measurement results with theoretical predictions was observed in the explored frequency band 800-5500 Hz that for the duct inside radius of a=0.077 m corresponded to the reduced frequency range 1.13
Źródło:
Acta Physica Polonica A; 2013, 123, 6; 1085-1089
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymptotic Formulae of the Modal Acoustic Impedance for the Asymmetric Vibrations of a Clamped Circular Plate
Autorzy:
Rdzanek, W.
Szemela, K.
Powiązania:
https://bibliotekanauki.pl/articles/1537549.pdf
Data publikacji:
2010-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Ks
43.20.Rz
43.40.+s
Opis:
The asymptotic and approximate formulae for the asymmetric modal acoustic self- and mutual-impedance have been presented for a clamped circular plate embedded into a flat rigid baffle. The formulae have been obtained for the wide frequency band covering the low frequencies, the high frequencies and the middle frequencies. The high frequency asymptotics have been achieved using the method of contour integral and the method of stationary phase. The products of the Bessel and Neumann functions have been expressed as the asymptotic expansions. Further, the approximate formulae valid within the low and middle frequencies have been obtained from the high frequency asymptotics using some mathematical manipulations. The formulae presented are valid for both the axisymmetric vibrations and the asymmetric vibrations.
Źródło:
Acta Physica Polonica A; 2010, 118, 1; 141-154
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wave Intensity Distributions in Complex Structures
Autorzy:
Tanner, G.
Chappell, D.
Maksimov, D.
Powiązania:
https://bibliotekanauki.pl/articles/1492500.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Dx
43.20.Dk
43.20.Rz
Opis:
The vibro-acoustic response of mechanical structures can in general be well approximated in terms of linear wave equations. Standard numerical solution methods comprise the finite or boundary element method in the low frequency regime and statistical energy analysis in the high-frequency limit. Major computational challenges are posed by the so-called mid-frequency problem - that is, composite structures where the local wavelength may vary by orders of magnitude across the components. Recently, a new approach towards determining the distribution of mechanical and acoustic wave energy in complex built-up structures improving on standard statistical energy analysis has been proposed. The technique interpolates between statistical energy analysis and ray tracing containing both these methods as limiting cases. The method has its origin in studying solutions of wave equation with an underlying chaotic ray-dynamics - often referred to as wave chaos. Within the new theory - dynamical energy analysis - statistical energy analysis is identified as a low resolution ray tracing algorithm and typical statistical energy analysis assumptions can be quantified in terms of the properties of the ray dynamics. We have furthermore developed a hybrid statistical energy analysis/finite element method based on random wave model assumptions for the short-wavelength components. This makes it possible to tackle mid-frequency problems under certain constraints on the geometry of the structure. Dynamical energy analysis and statistical energy analysis/finite element method calculations for a range of multi-component model systems will be presented. The results are compared with both statistical energy analysis results and finite element method as well as boundary element method calculations. Dynamical energy analysis emerges as a numerically efficient method for calculating mean wave intensities with a high degree of spatial resolution and capturing long range correlations in the ray dynamics.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-172-A-177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Low Frequency Approximation of the Sound Radiation Power of Two Vibrating Circular Pistons Embedded in Two Different Rigid Planes of a Three-wall Corner
Autorzy:
Rdzanek, W.
Szemela, K.
Powiązania:
https://bibliotekanauki.pl/articles/1196854.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Bi
43.20.El
43.20.Fn
43.20.Rz
Opis:
The problem of sound radiation by a system consisting of two vibrating circular pistons embedded in two of three different planes perpendicular to one another forming a three-wall corner is considered. The earlier published results dealing with the sound radiation by sources vibrating in a three-wall corner are the basis of analysis. According to the earlier studies, the exact formulae for acoustic power of radiation of two circular pistons are used. The formulae are expressed as double Fourier integrals. The active and reactive, self and mutual, components are separated from them as well as the corresponding expressions of the acoustic power of mirror images of the piston sources. The acoustic power of the two sources are expressed in the form of the Rayleigh formulae whereas, in the case of the mirror images, it is expressed in the form of the single series expansion containing spherical Bessel and Neumann functions. In the case of the mutual acoustic power of the sources, approximate formulae are presented for low frequencies. On the basis of the results obtained, the corresponding formulae valid for a two-wall corner are presented as the limiting transitions. All the results presented can be useful, e.g. in designing the room acoustics and outdoor system everywhere the free field conditions are disturbed by the acoustic waves reflected at rigid vertical walls for the wavelengths being considerably shorter than the geometric sizes of the walls.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-135-A-143
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Impedance of an Annular Piston Wobbling in a Flat Screen Around a Semi-infinite Circular Cylinder
Autorzy:
Pieczonka, D.
Rdzanek, W.
Powiązania:
https://bibliotekanauki.pl/articles/1400095.pdf
Data publikacji:
2013-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Bi
43.20.El
43.20.Fn
43.20.Rz
Opis:
A rigorous solution is presented for the problem of sound radiation by an oscillating and wobbling annular piston embedded concentrically in a perpendicular flat screen surrounding a semi-infinite circular cylindrical baffle. Two forms of the Green's function of the considered region are used. The acoustic impedance is presented in its integral form useful for numerical calculations which enable studying the effect of the acoustic waves scattering on the cylindrical baffle and the asymmetry of vibration velocity on the piston on the resultant acoustic impedance of the wobbling piston. It is shown that in the case of the vibrating piston under consideration, the reciprocity of acoustic impedance related to two modes of rigid body motion, oscillating and wobbling, does not occur.
Źródło:
Acta Physica Polonica A; 2013, 123, 6; 1078-1084
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Total Acoustic Power of Two Concentric Clamped Circular Plates Vibrating in a Fluid
Autorzy:
Rdzanek, W.
Powiązania:
https://bibliotekanauki.pl/articles/1402179.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Bi
43.20.El
43.20.Fn
43.20.Rz
Opis:
This study focuses on the problem of sound radiation by two concentric clamped flat plates, circular and annular, into the half-space. The system of three coupled differential equations comprising two equations of motions of plates and the wave equation, is solved exactly. Vibrations of plates are axisymmetric and time-harmonic with a single excitation frequency. The initial phase difference of excitations can be nonzero. Attenuation due to fluid loading and material damping is included. Kirchoff-Love and Kelvin-Voigt theories are applied. The effect of initial phase difference of excitations on the acoustic power radiated is examined as well as errors resulting from neglecting the fluid loading.
Źródło:
Acta Physica Polonica A; 2015, 128, 1A; A-41-A-45
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Acoustic Pressure Radiated by a Vibrating Circular Plate within the Fraunhofer Zone of the Three-Wall Corner Region
Autorzy:
Szemela, K.
Rdzanek, W.
Powiązania:
https://bibliotekanauki.pl/articles/1490263.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Ks
43.20.Rz
43.40.+s
43.20.-f
43.20.+g
Opis:
The Neumann boundary value problem has been solved for the region bounded by the three perfect rigid infinite baffles arranged perpendicularly to one another. The harmonically vibrating clamped circular plate embedded in one of the baffles is the sound source. It has been assumed that the amplitude of the plate's transverse vibrations is small to use the linear Kelvin-Voigt theory. The Green function has been applied to obtain the asymptotic formulae describing the distribution of the acoustic pressure within the Fraunhofer zone. The analysis of sound radiation has been performed for some selected surface excitations and for some different plate's locations. The acoustic pressure distribution has been examined including the acoustic attenuation and the internal attenuation of the plate's material.
Źródło:
Acta Physica Polonica A; 2012, 121, 1A; A-100-A-109
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Total Acoustic Power of a Clamped Circular Plate Located at the Boundary of Three-Wall Corner Region
Autorzy:
Szemela, K.
Rdzanek, W.
Pieczonka, D.
Powiązania:
https://bibliotekanauki.pl/articles/1504426.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.Ks
43.20.Rz
43.40.+s
43.20.-f
43.20.+g
Opis:
The energetic aspect of the sound radiation has been analyzed in the case of the three-wall corner region. This region is the part of space bounded by three baffles arranged perpendicularly to one another. The Neumann boundary value problem has been solved assuming that the sound source is the vibrating circular plate embedded in one of the baffles of the three-wall corner region. The Kelvin-Voigt theory of a visco-elastic plate has been used which allows to include internal attenuation existing in the plate material. It has been assumed that the sound source is excited to vibrations by the external pressure asymmetrically distributed on the plate surface. The modal coefficients of the acoustic impedance have been obtained in the form of the expressions containing single integrals only. The formula describing the acoustic power of the analyzed sound source has been presented as a fourfold infinite series containing the modal coefficients of the acoustic impedance. The influence of some asymmetric excitations on the acoustic power has been analyzed. The possibilities of the modelling some uniform excitations located on the plate fragment of the small area by the point force excitation has been examined. The influence of the transverse baffles on the acoustic power has also been investigated. It has been determined for which frequency the baffles influence on the acoustic power is the greatest.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1050-1060
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-10 z 10

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