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Wyszukujesz frazę "acoustic" wg kryterium: Temat


Tytuł:
Metrological capabilities of the acoustic testing laboratory - small anechoic chamber at the AGH Department of Mechanics and Vibroacoustics
Autorzy:
Kłaczyński, Maciej
Wszołek, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/2202424.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
anechoic chamber
acoustic testing laboratories
acoustic wedges
acoustic metrology
komora bezodbiciowa
laboratoria akustyczne
kliny akustyczne
metrologia akustyczna
Opis:
The small anechoic chamber is part of the research facilities of the Department of Mechanics and Vibroacoustics in AGH University of Science and Technology in Krakow and is a room corresponding to a free field, whose walls, ceiling and floor provide both very good sound absorption and isolation from external interference. The dimensions of the free space inside the chamber are 4.4 m x 3.8 m. x 3.6 m. The chamber was commissioned in the mid-1980s and has not undergone upgrades since. In December 2021, the upgrade of the small anechoic chamber was completed. As particularly important was the replacement of 5.5 thousand pieces of acoustic wedges made of polyurethane foam, which due to the aging process lost their sound-absorbing properties, for wedges made of mineral wool with glass fiber, adjustment of lighting inside the chamber to current standards, as well as equipping the chamber with a signal crossover and devices to regulate and monitor meteorological conditions inside the chamber. The paper presents a study of the properties of the small anechoic chamber in accordance with accepted standards for this type of rooms and its current research capabilities in the field of vibroacoustics in technology and medicine.
Źródło:
Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022217
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Systems modifying the acoustic properties of room furnishings
Autorzy:
Szeląg, Agata
Baruch-Mazur, Katarzyna
Brawata, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2146662.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
acoustic adaptation
sound absorbing elements
room acoustic parameters
adaptacja akustyczna
elementy dźwiękochłonne
parametry akustyczne wnętrz
Opis:
The article presents an idea how to increase the room acoustic absorption without significantly interfering with its appearance and architectural character. Based on scale model tests, analytical calculations and computer simulations, it has been shown that a noticeable reduction of room reverberation time and improvement of speech transmission index can be achieved by installing additional absorbing systems on selected furniture surfaces. By selecting the appropriate design and location of such systems, the functionality and appearance of the modified furniture can be maintained.
Źródło:
Vibrations in Physical Systems; 2022, 33, 1; art. no. 2022102
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of acoustical impedance of human skin
Autorzy:
Plaskota, Przemysław
Powiązania:
https://bibliotekanauki.pl/articles/127723.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
acoustic impedance
human skin
HRTF
impedancja akustyczna
skóra człowieka
Opis:
This paper presents the methodology of measuring acoustic impedance of human skin and discusses the results of the tests. Measurement of the acoustic impedance of human skin is a complex issue. The most difficult thing is related to the nature of the object of research. Cooperation of volunteer participating in the experiment is crucial in collecting accurate data. Appropriate measuring conditions must be provided because of the length of time required to conduct measurement. The Kundt tube method has been used as a research technique applied for evaluation of the material impedance. It was assumed that the results would differ with regard to different points chosen for measurement, located on the body of volunteer as well as with regard to the features of the skin structure of the volunteers participating in this experiment. Results have revealed that for different people similar parameters have been obtained. Moreover, results are alike for various measured points localized on person’s body.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-6
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic investigations of the contemporary churches in Poznań
Autorzy:
Sygulska, A.
Powiązania:
https://bibliotekanauki.pl/articles/127937.pdf
Data publikacji:
2014
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
church acoustics
acoustic investigation in church
akustyka kościoła
badanie akustyki
Opis:
The paper discusses acoustic issues of contemporary churches. Church interiors should be designed so as to obtain intelligibility of speech and simultaneously take organ music into account. It is a tough task as acoustic parameters required for speech and organ music are entirely different. Analysis of the issue was carried out on the basis of investigations in five contemporary churches in Poznań. In total, seven interiors were investigated as two of the churches were two-storeyed. The acoustic investigations were conducted by means of an omnidirectional sound source, a SVAN 945A Sound Level Meter and the DIRAC programme. RT, Ts, C80 and C50 were measured. The acoustic parameters were compared with values recommended for churches. The investigations allowed to draw clear conclusions concerning the influence of architecture of the interior on acoustic parameters.
Źródło:
Vibrations in Physical Systems; 2014, 26; 281-288
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of cavity edges shape on aerodynamic noise
Autorzy:
Łojek, Paweł
Czajka, Ireneusz
Powiązania:
https://bibliotekanauki.pl/articles/24202002.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
aeroacoustics
fluid-acoustic coupling
cavity noise
aeroakustyka
hałas generowany przez komorę
Opis:
In this article, the analysis of influence of cavity edge shapes on flow-generated noise is performed. The acoustic wave propagation in the channel, that result from the flow, was analyzed. Shape of upstream and downstream edges was modified. The hybrid method based on Navier-Stokes and Perturbed Convective Wave Equation was used to solve the unidirectional coupling. The research showed a significant influence of the modification of the shape of the cavity edges on the generated noise. The change of downstream corner allowed for significant reduction of noise in the entire analysed band and allowed for the reduction of overall sound pressure level (OASPL) by 5 dB. Modifications of the upstream edge did not bring such differences, change in OASPL was up to 1 dB. The obtained spectra of the sound pressure level showed compliance with the calculated natural frequencies of the analysed object, as well as with some of the Rossiter modal frequencies, typical for the phenomena occurring in the cavities.
Źródło:
Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022301
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synchronization system for underwater acoustic communications using in shallow waters
Autorzy:
Schmidt, Jan H.
Schmidt, Aleksander M.
Powiązania:
https://bibliotekanauki.pl/articles/24201990.pdf
Data publikacji:
2023
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
synchronization system
underwater acoustic communications
shallow water
układy synchronizacji
akustyczna komunikacja podwodna
wody płytkie
Opis:
A reliable synchronization system of the transmitted data frame has a significant impact on the efficiency of the underwater communication system. This applies in particular to communication systems dedicated to work in shallow waters, where the phenomenon of multipath permanently occurs. To overcome these difficulties, the concept of a synchronization system consisting of two broadband signals of opposite monotonicity was presented. The method of receiving these signals has been described in detail. The stochastic channel model with Rician fading and the Watermark simulator was used to test the efficiency of the synchronization system in the underwater multipath channel.
Źródło:
Vibrations in Physical Systems; 2023, 34, 1; art. no. 2023102
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uncertainty in vibroacoustic investigations – research challenges
Autorzy:
Batko, W.
Powiązania:
https://bibliotekanauki.pl/articles/128018.pdf
Data publikacji:
2014
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
vibroacoustics measurement
uncertainty assessment
environment acoustic hazards
pomiar wibroakustyczny
ocena niepewności
akustyczne zagrożenia środowiska
Opis:
The paper formulates the need of the modification of currently applied solutions of uncertainty assessments in vibroacoustic investigations, including the ones which use the convention rules developed by 7 international metrological organisations and described in the ‘Guide to the Uncertainty’. Reservations versus currently used solutions are given in the hereby paper. It directs attention toward assumptions limiting the likelihood assessment of uncertainties of the obtained acoustic results. It draws the possible ways of the problem solutions and related to them methods. It presents the need of connecting belonging to them algorithms with not classic statistical methods, allowing taking into account departures from generally used assumptions in presently applied solutions of uncertainty estimations of acoustic investigations results. The paper presents new research trends related to the uncertainty assessment of the environment acoustic hazards control. The presented results and their conclusions can constitute the base for wider verification of the correctness of the currently applied procedures of acoustic measurements assessment and related to them estimations of errors levels of the uncertainty estimation of acoustic investigations results.
Źródło:
Vibrations in Physical Systems; 2014, 26; 21-32
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic signal as a carrier of information on breathing sleep disorders
Autorzy:
Górnicka, Dorota
Klekot, Grzegorz
Michalik, Michał
Powiązania:
https://bibliotekanauki.pl/articles/128161.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
acoustic signal
diagnosis of sleep breathing disorders
sygnał akustyczny
diagnostyka zaburzeń oddychania podczas snu
Opis:
The statement that an acoustic signal can be a good tool for assessing breathing during sleep is not revealing and certainly raises no doubts. Based on the experience of technical diagnostics, one can formulate the hypothesis about the suitability of sounds accompanying breathing to infer any specific disorders. The verification of this hypothesis was supported by a research experiment combining the experience of doctors and engineers. The obtained results was used to create the simple application for the initial diagnosis of respiratory problems while sleeping at home. Assuming the minimization of the use of an advanced mathematical apparatus, features that are the symptoms of basic respiratory disorders have been extracted from the signal. Thanks to this approach, the developed tool not only informs about the disorder, but also signals the potential cause of the problem. Thus, the inference procedure that is the basis of a useful application can also support doctors at the stage of preclinical diagnosis.
Źródło:
Vibrations in Physical Systems; 2019, 30, 2; 1-6
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Designing of quasi one-dimensional acoustic filters using genetic algorithm
Autorzy:
Garus, Sebastian
Sochacki, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/128273.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
acoustic filter
genetic algorithm
transfer matrix
filtr akustyczny
algorytm genetyczny
macierz transmitancji
macierz przejścia
Opis:
In phononic quasi one-dimensional structures, there is a phenomenon of a phononic bandgap (PhBG), which means that waves of a given frequency do not propagate in the structure. The location and size of PhBG depend on the thickness of the layers, the type of materials used and their distribution in space. The theoretical study examined the transmission properties of quasi one-dimensional structures designed using a genetic algorithm (GA). The objective function minimized the transmission integral and integral of the absolute value of the transmission functions derivative (to eliminate high transmission peaks with a small half width) in a given frequency range. The paper shows the minimization of transmission in various frequency bands for a 40-layer structure. The distribution of multilayer structure transmission was obtained through the Transfer Matrix Method (TMM) algorithm. Structures surrounded by water were analyzed and built of layers of glass and epoxy resin.
Źródło:
Vibrations in Physical Systems; 2019, 30, 2; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the elastic cavity walls on cavity flow noise
Autorzy:
Łojek, Paweł
Czajka, Ireneusz
Gołaś, Andrzej
Suder-Dębska, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2146644.pdf
Data publikacji:
2021
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
FSI
Detached Eddy Simulations
acoustic analogy
cavity noise
analogia akustyczna
hałas generowany przez komorę
Opis:
In this study, computational fluid dynamics and computational aeroacoustics methods were used to investigate the influence of the elastic cavity walls on the noise generated by the flow over rectangular cavity. Two cases were considered and compared, one with rigid cavity walls, and one with elastic walls. In the latter case, the movement of the walls were solved by finite element modelling and coupled with CFD simulations. The noise generated by the flow over cavity was computed using Ffowcs Williams & Hawkings acoustic analogy. The increase of the sound pressure level for elastic walls case at frequency range of 1 kHz to 10 kHz is observed, compared to the rigid walls case.
Źródło:
Vibrations in Physical Systems; 2021, 32, 1; art. no. 2021109
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modelling of sound transmission through the window type partition
Autorzy:
Kwapisz, L.
Maurin, A.
Jakubowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/127902.pdf
Data publikacji:
2016
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
sound transmission
acoustic insulation
window
numerical simulation
transmisja dźwięku
izolacja akustyczna
okno
symulacja numeryczna
Opis:
The approach to numerical modelling of sound transmission through window type partitions is investigated in the paper. The laboratory conditions of reverberation room are simulated. The numerical and experimental results are compared. The impact of different model parameters on the sound insulation levels are evaluated.
Źródło:
Vibrations in Physical Systems; 2016, 27; 211-218
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective diagnostic of local noise sources with acoustic imaging
Autorzy:
Weyna, Stefan
Powiązania:
https://bibliotekanauki.pl/articles/128120.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
sound intensity
acoustic imaging
vibroacoustic
noise abatement
natężenie dźwięku
obrazowanie akustyczne
wibroakustyka
ograniczenie hałasu
Opis:
In this article, the author described methods of visualizing the acoustic flow and showed how these methods can help scientists understand the complex flow of acoustic energy in a real field. A graphical method for determining the distribution of acoustic waves in a real 3D flow field will be presented. Vector imaging of acoustic events is not possible with the use of traditional metrology applied in pressure acoustics. Based on research using measurements of sound intensity and distribution of vector acoustic field by acoustic orthogonal decomposition method (SI-AOD), the article will present examples of practical applications of these analyses. The described measurement technique, including the method of graphical presentation of results, enriches the knowledge about the mechanism of the flow of acoustic energy stream in real working conditions of the source. The SI-AOD analysis system sets a milestone in the monitoring of sound landscapes and the precise finds noise sources.
Źródło:
Vibrations in Physical Systems; 2019, 30, 2; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance of coherent modulation scheme used in acoustic underwater communication system
Autorzy:
Schmidt, Jan H.
Schmidt, Aleksander M.
Kochańska, Iwona
Powiązania:
https://bibliotekanauki.pl/articles/127757.pdf
Data publikacji:
2019
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
underwater acoustic communications
shallow underwater channel
coherent modulation
akustyczna komunikacja podwodna
płytki kanał podwodny
modulacja koherentna
Opis:
The development of an acoustic underwater communication system for shallow waters is still a big scientific and construction challenge. Currently, non-coherent modulations in combination with strong channel coding are used to achieve reliable communication with low rate in such a channel. To obtain transmission with a higher transmission rate, it is required to use coherent modulation. This paper presents the assumptions of such a transmission system and the results of data transmission carried out by this system in the channel with the Rician fading, which reflects the short range shallow water channel. A digital version of the carrier phase modulation known as Phase-Shift Keying was selected for simulation.
Źródło:
Vibrations in Physical Systems; 2019, 30, 1; 1-8
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Miniature omnidirectional sound sources used in acoustic scale modeling - measurements and validation
Autorzy:
Chojnacki, Bartłomiej
Powiązania:
https://bibliotekanauki.pl/articles/2202420.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
scale modelling
acoustic reduction models
room acoustics
electroacoustics
modelowanie redukcyjne
akustyczne modele redukcyjne
akustyka pomieszczeń
elektroakustyka
Opis:
Acoustic measurements such as scale modeling measurements require a particular type of miniature omnidirectional sound source. The most important aspects of those devices are small sizes (usually below 100 mm in diameter) and different frequency ranges compared to traditional, omnidirectional sound sources used in room acoustics. The required frequency range differs regarding the used scale factor in different models, which leads to the troubles in frequent source changes and the need for a unique source design for every model. The project will present the recent achievement in miniature omnidirectional sound sources development. The optimal sound sources for the given measurement functions were developed based on the previous numerical simulations and experiments such as FEM sound directivity simulations or transducers' parameters tolerance testing. The sound sources presented are used for applications such as acoustic sound insulation scale measurements (frequency range 800 ÷ 63 000 Hz), scaled reverberation chamber measurements (300 ÷ 80 000 Hz), or acoustic reduction models measurements (400 ÷ 70 000 Hz). The paper will cover a detailed technical explanation of the laboratory environment's source construction aspects and validation measurements.
Źródło:
Vibrations in Physical Systems; 2022, 33, 2; art. no. 2022201
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cinema hall adapted for opera singing - acoustic assessment
Autorzy:
Sygulska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/24201979.pdf
Data publikacji:
2023
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
acoustic adaptation
opera house acoustics
reverberation time in an opera house
adaptacja akustyczna
akustyka opery
czas pogłosu
Opis:
Room acoustics must be adapted to the intended function, and acoustic requirements vary depending on the type of sound production. Acoustic investigations were carried out in the hall of the Olimpia Academic Music Theater, which was originally a cinema. Acoustic requirements for cinemas are entirely different from those for opera singing. To ensure good acoustic conditions in the interior, an architectural adaptation or introduction of variable acoustics is necessary. The analysed interior was adapted to the needs of opera singing and the cinema function was abandoned. The objective of the research is to evaluate the acoustic quality of the hall for the purposes of an opera house.
Źródło:
Vibrations in Physical Systems; 2023, 34, 1; art. no. 2023115
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł

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