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Wyszukujesz frazę "Meissner, M." wg kryterium: Autor


Tytuł:
The response of a Helmholtz resonator to external excitation. Part II: Flow-induced resonance
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177560.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sound generation
flow-induced resonance
acoustic resonators
Opis:
In the paper a phenomenon of sound production in a resonator driven by an air jet has been investigated. Measurements of sound spectra at the closed end of the resonator cavity were performed to determine the influence of the jet velocity on the frequency and amplitude of excited acoustic oscillations. It was found that in the sound generation process two ranges of the jet velocity could be distinguished where different variations of the oscillation frequency with the growing jet velocity were observed. After the onset of oscillation the frequency increased fast with growing jet velocity and the frequency increment was directly proportional to a value of jet velocity. At higher flow velocities an increase in the frequency was still observed, but the frequency growth was much smaller. The experiment has shown also that due to an excitation of mechanical vibrations of the resonator elements a rapid change in the oscillation frequency occurred. Finally, the experimental data were compared to calculation results to examine the accuracy of the theoretical model, in which a force driving the resonator was predicted from the vortex sound theory and the resonator was modelled by an equivalent impedance circuit.
Źródło:
Archives of Acoustics; 2005, 30, 1; 57-71
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound Energy Field in a System of Coupled Rooms
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/1196695.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.55.Br
43.55.Ka
43.20.Ks
Opis:
The paper presents a theoretical basis of calculations of the sound intensity in enclosed spaces and shows results of numerical visualization of the active intensity in a room with absorptive walls formed by two coupled rectangular subrooms. The study was focused on the low-frequency range, therefore to describe the active and reactive intensities, the modal theory of room acoustics was applied. Space distribution of eigenfunctions, modal frequencies and modal damping coefficients were calculated numerically using the forced oscillator method (FOM) and the finite difference time-domain (FDTD) method. Based on theoretical and numerical results, the computer program has been developed to simulate the active intensity vector field when the room is excited by a harmonic point source. Calculation data have shown that the active intensity was extremely sensitive to position of the source since at a fixed source frequency, different source locations always generate different distributions of characteristic objects of the active sound field such as energy vortices and stagnation points. Because of complex room shape, the vortex centers are in most cases positioned irregularly inside the room. Almost regular arrangement of vortices was found only in the case when the source frequency was tuned to the frequencies of modes which were strongly localized in one of the subrooms.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-103-A-107
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of Acoustical Properties of Coupled Rooms Using Numerical Technique Based on Modal Expansion
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/1537509.pdf
Data publikacji:
2010-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.55.Br
43.55.Ka
43.20.Ks
Opis:
In the present study, the acoustic characteristics of coupled rooms were investigated using the computer modelling application based on the modal expansion method. A numerical procedure enables the computation of shape and frequency of eigenmodes, and allows one to predict sound decay times at any point of a room space. Results of numerical simulation have shown that along with a change in a coupling area the effect of a mode degeneration appeared and there are two main reasons for this. First, a mode degeneration is associated with a convergence of frequencies of neighbouring modes with a decrease of coupling area. Another reason for the mode degeneration are variations in a sequence of modes with a change in the coupling area. It was demonstrated that in the coupled rooms several modes exhibit a considerable localization. A degree of mode localization was described theoretically by the "existence surface" of mode and it was found that the localization phenomenon has a great effect on the reverberation process because for some absorbing material distributions it caused the double-slope decay characterized by steep initial and slow late sound decays.
Źródło:
Acta Physica Polonica A; 2010, 118, 1; 123-127
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accuracy Issues of Discrete Hilbert Transform in Identification of Instantaneous Parameters of Vibration Signals
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/1490326.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Uu
46.40.Ff
43.20.Ks
Opis:
In the paper, an accuracy of the discrete Hilbert transform method in a detection of amplitude and frequency of vibration signals has been examined. This issue was studied for sinusoidal damped vibrations often encountered in practical applications. It has been shown that an inexactness of the Hilbert transform generates fictitious oscillations of amplitude and frequency. For small damping of vibrations these oscillations were significant only at both ends of a discrete signal. An error induced by a numerical algorithm was especially severe for strongly damped vibrations because it manifested itself by a large overestimation of amplitude and erroneous jumps of frequency. To reduce the error generated by the Hilbert transform method, the appropriate modification of discrete signal was proposed.
Źródło:
Acta Physica Polonica A; 2012, 121, 1A; A-164-A-167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Modelling of Coupled Rooms: Evaluation of Decay Times via Method Employing Hilbert Transform
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/1504422.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.55.Br
43.55.Ka
43.20.Ks
43.60.Ac
Opis:
In the paper, a usefulness of the Hilbert transform in a computer modelling of reverberant behaviour of rooms is demonstrated for the enclosure consisting of two coupled subrooms. In numerical simulations a decay of the sound pressure is computed and the Hilbert transform methodology is used to determine an envelope of this decay. Calculation results have shown that, because of the mode localization, a distribution of absorbing material has a great influence on decay times evaluated from changes in the pressure envelope. For example, when a difference between the sound damping in subrooms is large, the localization effect is responsible for a creation of a nonlinear decay of the sound pressure level characterized by rapid early and slow late sound decays.
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 1031-1034
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Examination of the Effect of a Sound Source Location on the Steady-State Response of a Two-Room Coupled System
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177058.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
coupled room system
steady-state room response
potential and kinetic energy densities
localization of modes
Opis:
In this paper, the computer modelling application based on the modal expansion method is developed to study the influence of a sound source location on a steady- state response of coupled rooms. In the research, an eigenvalue problem is solved numerically for a room system consisting of two rectangular spaces connected to one another. A numerical procedure enables the computation of shape and frequency of eigenmodes, and allows one to predict the potential and kinetic energy densities in a steady-state. In the first stage, a frequency room response for several source positions is investigated, demonstrating large deformations of this response for strong and weak modal excitations. Next, a particular attention is given to studying how the changes in a source position influence the room response when a source frequency is tuned to a resonant frequency of a strongly localized mode.
Źródło:
Archives of Acoustics; 2011, 36, 4; 761-775
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Decay Times from Noisy Room Responses with Pure-Tone Excitation
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177891.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
reverberation
decay times
room response
background noise
coupled rooms
Opis:
Reverberant responses are widely used to characterize acoustic properties of rooms, such as the early decay time (EDT) and the reverberation times T20 and T30. However, in real conditions a sound decay is often deformed by background noise, thus a precise evaluation of decay times from noisy room responses is the main problem. In this paper this issue is examined by means of numerical method where the decay times are estimated from the decay function that has been determined by nonlinear polynomial regression from a pressure envelope obtained via the discrete Hilbert transform. In numerical experiment the room responses were obtained from simulations of a sound decay for two-room coupled system. Calculation results have shown that background noise slightly affects the evaluation of reverberation times T20 and T30 as long as the signal-to-noise ratio (SNR) is not smaller than about 25 and 35 dB, respectively. However, when the SNR is close to about 20 and 30 dB, high overestimation of these times may occur as a result of bending up of the decay curve during the late decay.
Źródło:
Archives of Acoustics; 2013, 38, 1; 47-54
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Novel Method for Determining Optimum Dimension Ratios for Small Rectangular Rooms
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177897.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
small room
optimum dimension ratios
room impulse response
frequency room response
Opis:
A new method for determining optimum dimension ratios for small rectangular rooms has been presented. In a theoretical model, an exact description of the room impulse response was used. Based on the impulse response, a frequency response of a room was calculated to find changes in the sound pressure level over the frequency range 20-200 Hz. These changes depend on the source and receiver positions, thus, a new metric equivalent to an average frequency response was introduced to quantify the overall sound pressure variation within the room for a selected source position. A numerical procedure was employed to seek a minimum value of the deviation of the sound pressure level response from a smooth fitted response determined by the quadratic polynomial regression. The most smooth frequency responses were obtained when the source was located at one of the eight corners of a room. Thus, to find the best possible dimension ratios, in the numerical procedure the optimal source position was assumed. Calculation results have shown that optimum dimension ratios depend on the room volume and the sound damping inside a room, and for small and medium volumes these ratios are roughly 1 : 1.48 : 2.12, 1 : 1.4 : 1.89 and 1 : 1.2 : 1.45. When the room volume was suitably large, the ratio 1 : 1.2 : 1.44 was found to be the best one.
Źródło:
Archives of Acoustics; 2018, 43, 2; 217-225
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Cross-Sectional Area Discontinuities in Closed Hard-Walled Ducts on Frequency of Longitudinal Modes
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177934.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
longitudinal duct modes
discontinuity in duct cross-section
contraction ratio
Opis:
A simple analytical method is developed to estimate frequencies of longitudinal modes in closed hard-walled ducts with discontinuities in a cross-sectional area. The approach adopted is based on a general expression for the acoustic impedance for a plane wave motion in a duct and conditions of impedance continuity at duct discontinuities. Formulae for mode frequencies in a form of transcendental equations were found for one, two and three discontinuities in a duct cross-section. An accuracy of the method was checked by a comparison of analytic predictions with calculation data obtained by use of numerical implementation based on the forced oscillator method with a finite difference algorithm.
Źródło:
Archives of Acoustics; 2010, 35, 3; 421-435
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of Reverberant Properties of Enclosures via a Method Employing a Modal Representation of the Room Impulse Response
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177946.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
indoor reverberation
room impulse response
modal expansion method
decay times
Opis:
A theoretical method has been presented to describe sound decay in enclosures and simulate the room impulse response (RIR) employed for prediction of the indoor reverberation characteristics. The method was based on a solution of wave equation with the form of a series whose time-decaying components represent responses of acoustic modes to an impulse sound source. For small sound absorption on room walls this solution was found by means of the method of variation of parameters. A decay function was computed via the time-reverse integration of the squared RIR. Computer simulations carried out for a rectangular enclosure have proved that the RIR function reproduces the structure of a sound field in the initial stage of sound decay sufficiently well. They have also shown that band-limitedness of the RIR has evident influence on the shape of the decay function and predicted decay times.
Źródło:
Archives of Acoustics; 2016, 41, 1; 27-41
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Active vibroacoustic control of plate structures with arbitrary boundary conditions
Autorzy:
Nowak, Ł.
Zieliński, T. G.
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/31343106.pdf
Data publikacji:
2013
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
vibroacoustics
active control
plate vibrations
aktywne sterowanie
wibroakustyka
Opis:
The paper describes briefly some main aspects of the active feedback control system that has been developed and constructed for reduction of vibroacoustic emission of vibrating plate structures with arbitrary boundary conditions. Relations between the forms and frequency of the vibrations induced by an external harmonic excitation and the distribution of the generated acoustic pressure field are investigated using the developed numerical model based on indirect variational boundary element method. The aim of the control system is to minimize the sound pressure level in a given point of the ambient space. The system uses small, rectangle-shaped piezoelectric transducers as both sensors and actuators. The transducers are connected in a number of independent feedback loops, and the feedback gains are the control parameters which are optimized using the developed optimal control algorithm. The constructed active system has been tested for the stability and control performance during experimental research performed in an anechoic chamber. Results of experiments are presented in the paper, proving a high level of noise reduction and a good agreement with numerical predictions.
Źródło:
IPPT Reports on Fundamental Technological Research; 2013, 4; 5-9
2299-3657
Pojawia się w:
IPPT Reports on Fundamental Technological Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Broadside coupled stripline with double-side UC-PBG structure
Autorzy:
Meissner, P.
Kitliński, M.
Powiązania:
https://bibliotekanauki.pl/articles/309389.pdf
Data publikacji:
2005
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
UC-PBG
uniplanar photonic bandgap
coupler
3 dB coupler
broadside coupled line coupler
stripline coupler
slow-wave effect
photonic
PBG bandgap
electromagnetic band gap
EBG
Opis:
A stripline waveguide with double-side UC-PBG pattern is considered. To verify usefulness of the stripline structure with UC-PBG a 3 dB coupler has been designed and fabricated. Reduction of the coupler size (due to slow wave effect) has been predicted and observed. Numerical and experimental investigation confirmed enhanced backward coupling phenomena.
Źródło:
Journal of Telecommunications and Information Technology; 2005, 2; 61-64
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Liczebność ptaków wodnych na Zatoce Gdańskiej w okresie wrzesień 2016 - kwiecień 2017
Numbers of waterbirds on the Bay of Gdansk between September 2016 and April 2017
Autorzy:
Meissner, W.
Kosmicki, A.
Kozakiewicz, M.
Kaszak, S.
Powiązania:
https://bibliotekanauki.pl/articles/79481.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Zoologiczne
Tematy:
ptaki
ptaki wodne
sklad gatunkowy
liczebnosc populacji
Zatoka Gdanska
lata 2016-2017
Źródło:
Ornis Polonica; 2017, 58, 3
2081-9706
Pojawia się w:
Ornis Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Liczebność ptaków wodnych na Zatoce Gdańskiej w okresie wrzesień 2013 - kwiecień 2014
Numbers of waterbirds on the Bay of Gdansk between September 2013 and April 2014
Autorzy:
Meissner, W.
Sciborski, M.
Kosmicki, A.
Wojcik, C.
Powiązania:
https://bibliotekanauki.pl/articles/79578.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Zoologiczne
Tematy:
ptaki
ptaki wodne
sklad gatunkowy
liczebnosc populacji
Zatoka Gdanska
lata 2013-2014
Źródło:
Ornis Polonica; 2015, 56, 1
2081-9706
Pojawia się w:
Ornis Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gniazdowanie rybitwy czubatej Sterna sandvicensis w Polsce w latach 2006-2013
Nesting of the Sandwich Tern Sterna sandvicensis in Poland in 2006-2013
Autorzy:
Meissner, W.
Bzoma, S.
Ziecik, P.
Wybraniec, M.
Powiązania:
https://bibliotekanauki.pl/articles/79725.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Zoologiczne
Tematy:
ptaki
rybitwa czubata
Sterna sandvicensis
populacje legowe
liczebnosc populacji
gniazdowanie
gniazda ptasie
legi ptakow
sukces rozrodczy
kolonie legowe
lata 2006-2013
Zatoka Gdanska
rezerwat Mewia Lacha
Polska
Źródło:
Ornis Polonica; 2014, 55, 2
2081-9706
Pojawia się w:
Ornis Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł

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