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Tytuł:
Thermal lenses caused by any acoustic source
Autorzy:
Perelomova, A.
Powiązania:
https://bibliotekanauki.pl/articles/332019.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
thermal lens
acoustic source
Opis:
The modern theory concerning to the heating cased by powerful sound source is presented. In contrast to the well-known approach allowing to calculate slowly varying heating due to periodic ultrasound, any acoustic sources may be treated. Subtle temporal structure of thermal lens forming may be traced. Formulae governing the forming of the thermal lens by arbitrary (including non-periodic) source are presented. The process is illustrated by some figures.
Źródło:
Hydroacoustics; 2003, 6; 171-176
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multitone nonlinear coding
Autorzy:
Nowicki, A.
Wójcik, J.
Secomski, W.
Powiązania:
https://bibliotekanauki.pl/articles/331604.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
MNC method
virtual fields
acoustic source
Opis:
A new method that utilizes nonlinear properties of tissue (or another media) to improve ultrasound image resolution is presented. In our novel method the acoustic source is activated with two tones burst (2.2 and 4.4 MHz) with specially designed polarization of the individual tone burst. This new approach is called multi tone nonlinear coding MNC because the choice of polarization of the both tones (and their amplitudes) allowing optimization of the receiving properties depends on the nonlinear properties of tissue. The calculations were done for two tones bursts propagating in the tissue-like lossy medium with absorption of 7 Np/mźMHz. The concept of the Virtual Fields was introduced to explain abilities and properties of pulse inversion and MNC method and to compare both. Comparison of the spatial field distribution obtained using MNC and conventional harmonic imaging approach, in which the first harmonic is used to reconstruct the image are presented.
Źródło:
Hydroacoustics; 2008, 11; 289-298
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fixed passive array orientation estimation by bearing analysis of moving acoustic source
Autorzy:
Henclik, S.
Powiązania:
https://bibliotekanauki.pl/articles/332536.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
moving acoustic source
acoustics
array orientation
Opis:
Precise source localization in passive sonar with linear, horizontal passive array and matched beam processing algorithms requires, among others, accurate determination of the fixed array position and orientation. Geographical coordinates of the array can be evaluated quite simple with precise GPS receiver. Especially important problem is then the accurate determination of the array orientation. It is not a trivial problem and simple compass measurements may produce precision troubles. At the paper a method that compares the known trajectory of a moving acoustic source and its bearings computed with the array system software is developed. The method is based on minimizing the function of square error between the true and candidate-estimated target positions. Another interesting feature of proposed algorithm is the possibility of optimizing the error function with respect to parameters that model in an assumed way signal prapagation characteristics.
Źródło:
Hydroacoustics; 2003, 6; 243-250
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on Airflow Background Noise Suppression for Aeroacoustic Wind Tunnel Testing
Autorzy:
Li, Yuanwen
Li, Min
Feng, Daofang
Yang, Debin
Wei, Long
Powiązania:
https://bibliotekanauki.pl/articles/2141671.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aeroacoustic measurement
acoustic source localization
EEMD; background noise suppression
wind tunnel test.
Opis:
The microphone data collected in aeroacoustic wind tunnel test contains not only desired aeroacoustic signal but also background noise generated by the jet or the valve of the wind tunnel, so the desired aeroacoustic characteristics is difficult to be highlighted due to the low Signal-to-Noise Ratio (SNR). Classical cross spectral matrix removal can only reduce the microphone self-noise, but its effect is limited for jet noise. Therefore, an Airflow Background Noise Suppression method based on the Ensemble Empirical Mode Decomposition (ABNSEEMD) is proposed to eliminate the influence of background noise on aeroacoustic field reconstruction. The new method uses EEMD to adaptively separate the background noise in microphone data, which has good practicability for increasing SNR of aeroacoustic signal. A localization experiment was conducted by using two loudspeakers in wind tunnel with 80 m/s velocity. Results show that proposed method can filter out the background noise more effectively and improve the SNR of the loudspeakers signal compared with spectral subtraction and cepstrum methods. Moreover, the aeroacoustic field produced by a NACA EPPLER 862 STRUT airfoil model was also measured and reconstructed. Delay-and-sum beamforming maps of aeroacoustic source were displayed after the background noise was suppressed, which further demonstrates the proposed method’s advantage.
Źródło:
Archives of Acoustics; 2022, 47, 2; 241-257
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Direction Estimation and Tracking of Coherent Sources Using a Single Acoustic Vector Sensor
Autorzy:
Wajid, Mohd
Kumar, Arun
Bahl, Rajendar
Powiązania:
https://bibliotekanauki.pl/articles/176542.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustic intensity
acoustic vector sensor
DOA
Direction of Arrival
FEM
Finite Element Method
tracking of acoustic source
Opis:
A single acoustic vector sensor (AVS) cannot be used to find the direction-of-arrival (DOA) of two or more coherent (fully correlated) sources. We have proposed a technique for estimating DOAs (in 2D geometry) of two simultaneous coherent sources using single AVS under the assumption that acoustic sources enter in the field sequentially. The DOA estimation has been investigated with two different configurations of AVS, each consisting of three microphones in a plane. The technique has been also applied in tracking (a) an acoustic source in the presence of stationary interfering coherent source and (b) two coherent sources when the sources are changing their locations alternatively. The experimental environment has been generated using the Finite-Element Method tool viz. COMSOL to corroborate the proposed scheme.
Źródło:
Archives of Acoustics; 2020, 45, 2; 209-219
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Source Localization Using Kernel-based Extreme Learning Machine in Distributed Microphone Array
Autorzy:
Wang, Rong
Chen, Zhe
Yin, Fuliang
Powiązania:
https://bibliotekanauki.pl/articles/1953510.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
extreme learning machine
acoustic source localization
distributed microphone array
generalized cross correlation function
Opis:
Acoustic source localization using distributed microphone array is a challenging task due to the influences of noise and reverberation. In this paper, acoustic source localization using kernel-based extreme learning machine in distributed microphone array is proposed. Specifically, the space of interest is divided into some labeled positions, and the candidate generalized cross correlation function in each node is treated as the feature mapped into the hidden nodes of extreme learning machine. During the training phase, by the implementation of kernel function, the output weights of the classifier are calculated and do not need to be tuned. After the kernel-based extreme learning machine (K-ELM) is well trained, the measured generalized cross correlation data are fed into the K-ELM classifier, and the output is the estimated acoustic source position. The proposed method needs less human intervention for both training and testing and it does not need to calibrate the node in advance. Simulation and real-world experimental results reveal that the proposed method has extremely fast training and testing speeds, and can obtain better localization performance than steered response power, K-nearest neighbor, and support vector machine methods.
Źródło:
Archives of Acoustics; 2021, 46, 1; 67-78
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of acoustic field for a parametric focusing source using the spheroidal beam equation
Autorzy:
Yu, L.
Li, J.
Shi, C.
Powiązania:
https://bibliotekanauki.pl/articles/258564.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
parametric focusing source
difference frequency wave
SBE
acoustic field
Opis:
A theoretical model of acoustic field for a parametric focusing source on concave spherical surface is proposed. In this model, the source boundary conditions of the Spheroidal Beam Equation (SBE) for difference frequency wave excitation were studied. Propagation curves and beam patterns for difference frequency component of the acoustic field are compared with those obtained for Khokhlov-Zabolotskaya-Kuznetsov (KZK) model. The results demonstrate that the focused parametric model of SBE is good valid for a large aperture angle in the strongly focused acoustic field. It is also investigated that high directivity and good focal ability with the decreasing of downshift ratio and the increasing of half-aperture angle for the focused parametric model of SBE.
Źródło:
Polish Maritime Research; 2015, S 1; 43-47
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of Acoustic Camera for Noise Sources Localization and Noise Reduction in the Industrial Plant
Autorzy:
Fiebig, Wiesław
Dąbrowski, Damian
Powiązania:
https://bibliotekanauki.pl/articles/178071.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
noise source localization
noise reduction
industrial noise control
acoustic camera
Opis:
The paper presents results of the localization of main noise sources in the industrial plant. Identification of main noise sources was made with an acoustic camera using Beamforming Method. Parallel to the measurements by means of the acoustic camera, sound level measurements on the main noise sources have been performed. Based on the calculations, prediction regarding the noise emission at residential buildings located near to the plant has been determined. Acoustic noise maps have been performed with LEQ Professional software, which includes the 3D geometry of the buildings inside the plant. It has been established that, after introduction of noise reduction measures in the plant, the noise levels at the observation points in the residential area meets the limit values.
Źródło:
Archives of Acoustics; 2020, 45, 1; 111-117
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modulation Mechanism of Acoustic Scattering in Underwater Corner Reflectors with Acoustic Metasurfaces
Autorzy:
Du, Jiaman
Peng, Zilong
Ge, Lili
Lyu, Shijin
Zhou, Fulin
Liu, Yan
Powiązania:
https://bibliotekanauki.pl/articles/31339794.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustic scattering
metasurface
ray tracing
corner reflector
virtual source method
Opis:
Using the tunderwater corner reflector (CR) to simulate the acoustic scattering characteristics of the military target is a new technology to counter active sonar detection. Existing underwater CRs only have the ability to interfere with the acoustic field, but have limitations in acoustic wave modulation. Therefore, acoustic metasurfaces applied on CRs to enhance the ability of acoustic wave modulation has a great application prospect. A fast prediction method based on the Kirchhoff approximation (KA) and the ray tracing theory is proposed to calculate the acoustic scattering characteristics of CR with acoustic metasurfaces in grooves array type. The accuracy of the method is verified by the finite element method (FEM) simulation. The modulation effect of CR with grooves array in different gradient combinations on the structural scattering acoustic field is analyzed. The research shows that the CR with different combinations of the acoustic metasurface has an obvious modulation effect on the amplitude of the acoustic waves and the deflection of acoustic field. In particular, the grooves array in combination with positive and negative gradients has an obvious deflection impact on the scattering acoustic field.
Źródło:
Archives of Acoustics; 2023, 48, 4; 465-473
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microphone Based Acoustic Vector Sensor for Direction Finding with Bias Removal
Autorzy:
Wajid, Mohd
Kumar, Arun
Bahl, Rajendar
Powiązania:
https://bibliotekanauki.pl/articles/2141636.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acoustic measurements
acoustic sensor
acoustic vector sensor
direction-of-arrival estimation
finite element analysis
microphones
particle velocity
sound source localization
Opis:
The acoustic vector sensor (AVS) is used to measure the acoustic intensity, which gives the direction-of-arrival (DOA) of an acoustic source. However, while estimating the DOA from the measured acoustic intensity the finite microphone separation (d) in a practical AVS causes angular bias. Also, in the presence of noise there exists a trade off between the bias (strictly increasing function of d) and variance (strictly decreasing function of d) of the DOA estimate. In this paper, we propose a novel method for mitigating the angular bias caused due to finite microphone separation in an AVS. We have reduced the variance by increasing the microphone separation and then removed the bias with the proposed bias model. Our approach employs the finite element method (FEM) and curves fitting to model the angular bias in terms of microphone separations and frequency of a narrowband signal. Further, the bias correction algorithm based on the intensity spectrum has been proposed to improve the DOA estimation accuracy of a broadband signal. Simulation results demonstrate that the proposed bias correction scheme significantly reduces the angular bias and improves the root mean square angular error (RMSAE) in the presence of noise. Experiments have been performed in an acoustic full anechoic room to corroborate the effect of microphone separation on DOA estimation and the efficacy of the bias correction method.
Źródło:
Archives of Acoustics; 2022, 47, 2; 151-167
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Underwater target direction of arrival estimation by small acoustic sensor array based on sparse bayesian learning
Autorzy:
Wang, B.
He, C.
Powiązania:
https://bibliotekanauki.pl/articles/260588.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
DOA
underwater acoustic signal processing
sparse Bayesian learning
temporally correlated source
Opis:
Assuming independently but identically distributed sources, the traditional DOA (direction of arrival) estimation method of underwater acoustic target normally has poor estimation performance and provides inaccurate estimation results. To solve this problem, a new high-accuracy DOA algorithm based on sparse Bayesian learning algorithm is proposed in terms of temporally correlated source vectors. In novel method, we regarded underwater acoustic source as a first-order auto-regressive process. And then we used the new algorithm of multi-vector SBL to reconstruct the signal spatial spectrum. Then we used the CS-MMV model to estimate the DOA. The experiment results have shown the novel algorithm has a higher spatial resolution and estimation accuracy than other DOA algorithms in the cases of less array element space and less snapshots.
Źródło:
Polish Maritime Research; 2017, S 2; 95-102
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of equivalent source method to identification of models of noise sources in automotive air conditioning systems
Zastosowanie metody ekwiwalentnych źródeł w celu identyfikacji modeli źródeł hałasu w układzie klimatyzacji samochodowej
Autorzy:
Bzymek, A.
Powiązania:
https://bibliotekanauki.pl/articles/327874.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
metoda ekwiwalentnych źródeł
ESM
moduł HVAC
ciśnienie akustyczne
equivalent source method
HVAC unit
acoustic pressure
Opis:
The paper deals with the experimental analysis of noise sources in Automotive Air Conditioning Systems (AACS), especially a part of the system - Heating Ventilating Air Conditioning (HVAC) unit. Presented approach was based on Equivalent Source Method (ESM) which is an inverse method of identification of models of noise sources. In order to model the acoustic pressure above the main outlet of the HVAC unit, a model consisting of a few equivalent sources was elaborated.
Artykuł przedstawia eksperymentalną analizę źródeł hałasu w systemie klimatyzacji samochodowej, szczególnie jej części - w module HVAC. Prezentowane podejście bazuje na metodzie ekwiwalentnych źródeł w celu identyfikacji modeli źródeł hałasu. W artykule przedstawiono główne założenia metody, opisano przebieg i sposób realizacji badań. Uzyskane wyniki opatrzono komentarzem.
Źródło:
Diagnostyka; 2006, 2(38); 65-68
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie holografii akustycznej w ocenie mocy wypromieniowanej przez mikropompę zębatą
Application of acoustic holography in assessing the power radiated by micro gear pump
Autorzy:
Osiński, P.
Powiązania:
https://bibliotekanauki.pl/articles/270003.pdf
Data publikacji:
2012
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
mikropompa zębata
holografia akustyczna
źródła dźwięku
lokalizacja
micro gear pump
acoustic holography
sound source
localization
Opis:
W artykule przedstawiono przykładowe wyniki badań akustycznych wykonanych dla mikropompy zębatej. Badania przeprowadzono z wykorzystaniem zestawu do holografii akustycznej. Wykorzystana aparatura pozwala na określenie wypromieniowanej mocy akustycznej oraz na przeprowadzenie lokalizacji źródeł dźwięku, bazując na algorytmie STSF przestrzennej transformacji pól dźwiękowych.
In article are examples of acoustic test results carried out on the microhydraulic gear pump. Testing was conducted using a set of sound to holography. Used apparatus allows definition of radiated sound power and to carry out the location of the sound sources based on algorithm STSF spatial transformation of sound fields.
Źródło:
Inżynieria Maszyn; 2012, R. 17, z. 4; 93-106
1426-708X
Pojawia się w:
Inżynieria Maszyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of Sound Power Levels and Surface Absorption Coefficients in Multi-Source Industrial Buildings by Using a Simplified Diffusion Model
Autorzy:
Sequeira, M. E.
Cortínez, V. H.
Powiązania:
https://bibliotekanauki.pl/articles/177679.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
industrial noise
noise source identification
sound absorption coefficient
two-dimensional acoustic diffusion model
simulated annealing algorithm
Opis:
This article deals with the identification of sound powers and absorption surface coefficients in multisource industrial buildings from the knowledge of the sound pressure levels (SPLs) at several monitoring points. This inverse problem is formulated as one of optimisation in which the objective function is the difference between the measured and predicted SPLs. The methodology combines the use of a simplified acoustic diffusion model with the simulated annealing optimisation technique. The former is a recently developed model for estimating the SPLs in a fast and sufficiently accurate form. The low computational cost of the model constitutes the major advantage for the optimisation procedure due to the great numer of simulations required. Numerical examples are given to show the efficiency of the proposed approach.
Źródło:
Archives of Acoustics; 2018, 43, 1; 93-102
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design Sensitivity Studies on a Hydroacoustic Projector Using an Experimentally Validated Easy-to-Build Model
Autorzy:
Sreejith, Vattaparambil Sreedharan
Tiwari, Nachiketa
Powiązania:
https://bibliotekanauki.pl/articles/2141678.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
low frequency sound source
underwater transducer
fluid power
hydro-electro-mechano-acoustic analogy
hydraulic valve
piston
cylinder
Opis:
Hydroacoustic projectors are useful for generating low frequency sounds in water. Existing works on hydroacoustic projectors require two significant enhancements, especially for designers. First, we need to understand the influence of important projector design parameters on its performance. Such insights can be very useful in developing a compact and efficient projector. Second, there is a need for an integrated model of the projector based on easily available and user-friendly numerical tools which do not require development of complex customised mathematical analogs of projector components. The present work addresses both such needs. Towards these goals, an experimentally validated, easy-to-build projector model was developed and used to conduct design sensitivity studies. We show that reductions in pipe compliance and air content in oil, and an increase in orifice discharge coefficient can yield remarkable improvements in projector’s SPL. We also show that reductions in pipe length and cylinder diameter cause moderate improvements in performance in mass and stiffness controlled regions, respectively. In contrast, the projector performance is insensitive to changes in pistonic mass, cylinder length, and diaphragm stiffness. Finally, we report that while pipe compliance and air content in oil can sharply alter system resonance, the effects of changes in pipe length and pistonic mass on it are moderate in nature.
Źródło:
Archives of Acoustics; 2022, 47, 1; 113-124
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 20

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