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    Wyświetlanie 1-13 z 13
    Tytuł:
    Normative measurements of noise at CNC machines work stations
    Autorzy:
    Mika, D.
    Józwik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/103079.pdf
    Data publikacji:
    2016
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    noise
    noise measurement
    acoustic pressure
    acoustic absorption
    CNC machines
    Opis:
    Minimisation of noise at a workstation is among fundamental tasks for maintaining safety at work, both in terms of health (the auditory system in particular) as well as work comfort. Thus, it is very important to systematically monitor noise levels by carrying out reliable measurements at a workstation. The method of performing noise measurements at workstations of specific machines is normalised so the results of such measurements for different machines is comparable. This paper presents noise measurements for DMC 635 numerically controlled milling machine, performed in accordance with PN ISO 230-5:2002 norm. The results showed that the level of noise at the operator’s workstation significantly exceeds the norm at certain machining parameters. The results of tests are concluded as detailed recommendation for the CNC machine tool operator to use hearing protection when at work.
    Źródło:
    Advances in Science and Technology. Research Journal; 2016, 10, 30; 138-143
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design, Manufacture and Characterization of an Acoustic Barrier Made of Multi-Phenomena Cylindrical Scatterers Arranged in a Fractal-Based Geometry
    Autorzy:
    Casteneira-Ibanez, S.
    Rubio, C.
    Romero-Garcia, V.
    Sanchez-Perez, J. V.
    Garcia-Raffi, L. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/176662.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic arrays
    acoustic attenuation
    acoustic wave absorption
    acoustic wave scattering
    phononic crystals
    acoustic barrier
    physical effect of sound
    Opis:
    In this work we present the design and the manufacturing processes, as well as the acoustics standard- ization tests, of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic Crystals. The multiple scattering of waves inside these structures leads to attenuation bands related to the periodicity of the structure by means of Bragg scattering. In order to design the acoustic barrier, two strategies have been used: First, the arrangement of scatterers is based on fractal geometries to maximize the Bragg scattering; second, multi-phenomena scatterers with several noise con- trol mechanisms, as resonances or absorption, are designed and used to construct the periodic array. The acoustic barrier reported in this work provides a high technological solution in the field of noise control.
    Źródło:
    Archives of Acoustics; 2012, 37, 4; 455-462
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on Sound Absorption of Road Acoustic Screens Under Simulated Weathering
    Autorzy:
    Nowoświat, A.
    Bochen, J.
    Dulak, L.
    Żuchowski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/176782.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic screens
    ageing process
    sound absorption
    durability
    Opis:
    The present paper is comparing the results of research studies carried out for three road acoustic screens of different design and different number of damping layers. For the tests, we selected timber or steel screens with a traditional multilayer structure and also one innovative type of simplified design. With respect to particular panels, their sound absorption properties were investigated in the reverberation chamber after they had been subjected to simulated weathering. In the process, two screens were subjected to the aging tests of 50-500 cycles in a special climatic chamber, and the innovative screens were subjected to 1000 cycles. The procedure was repeated every 50 or 100 cycles in order to obtain the changes of acoustic characteristics. The changes taking place in the absorbing material were also investigated with the use of scanning electron microscopy method (SEM). Basing on the obtained results and on the statistical analysis, the capability to maintain acoustic properties by the panels during their service life in natural conditions was estimated. For that purpose, linear statistical models were worked out, which were then applied to estimate the value of the single number sound absorption coefficient after successive aging cycles as well as the predicted time periods of acoustic class changes.
    Źródło:
    Archives of Acoustics; 2018, 43, 2; 323-337
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Utilizing Hollow-Structured Bamboo as Natural Sound Absorber
    Autorzy:
    Putra, A.
    Khair, F. A.
    Nor, M. J. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177960.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    bamboo
    hollow structure
    acoustic absorber
    absorption coefficient
    Opis:
    Studies to find alternative low environmental-impact materials for acoustic absorbers are still progressing, particularly those originated from natural materials. However, most of the established works are mainly focused on the fibrous-type absorbers. Discussion on the non-fibrous-type absorbers is still lacking and this therefore becomes the objective of this paper. Use of bamboo by utilizing its hollow structure to absorb sound energy is discussed here. The normal incidence absorption coefficient was measured based on the length and diameter of the bamboo, as well as different arrangement of the bamboo structure subjected to the incidence sound, namely, axial, transverse, and crossed-transverse arrangements. The trend of absorption coefficient appears in peaks and dips at equally spacing frequencies. For all arrangements the peak of absorption can reach above 0.8. Introducing an air gap behind the bamboo shifts the peak absorption to lower frequency. Covering the front surface of the absorber improves the sound absorption coefficient for axial arrangement by widening the frequency range of absorption also towards lower frequency range. The transverse arrangement is found to have average absorption coefficient peaks of 0.7 above 1.5 kHz. By arranging the bamboo structure with crossed-transverse arrangement, the suppressed absorption peaks in normal transverse arrangement can be recovered.
    Źródło:
    Archives of Acoustics; 2015, 40, 4; 601-608
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimating Surface Acoustic Impedance With the Inverse Method
    Autorzy:
    Piechowicz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/90473.pdf
    Data publikacji:
    2011
    Wydawca:
    Centralny Instytut Ochrony Pracy
    Tematy:
    room acoustics
    sound absorption coefficient
    acoustic impedance
    Opis:
    Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.
    Źródło:
    International Journal of Occupational Safety and Ergonomics; 2011, 17, 3; 271-276
    1080-3548
    Pojawia się w:
    International Journal of Occupational Safety and Ergonomics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurements of the Sound Absorption Coefficient of Auditorium Seats for Various Geometries of the Samples
    Autorzy:
    Rubacha, J.
    Pilch, A.
    Zastawnik, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/176676.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sound absorption
    room acoustics
    modelling of acoustic parameters
    Opis:
    This paper presents the results of measurements of the sound absorption coefficient of auditorium seats carried out in the laboratory using two methods. In the first one, small blocks of seats in various arrangements were studied in a reverberation chamber to determine the absorption coefficient of an auditorium of infinite dimensions. The results were compared to the values of the absorption coefficient measured using the second method, which involved samples enclosed within a frame screening the side surfaces of other auditorium blocks. The results of both methods allowed for the assessment of the sound absorption coefficient of an auditorium of any dimensions while taking into account the sound absorption by the side surfaces. The method developed by the authors will simplify the currently known measurement procedures.
    Źródło:
    Archives of Acoustics; 2012, 37, 4; 483-488
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Compensation of Air Absorption of Sound in Scale Model Measurements
    Autorzy:
    Ćirić, D. G.
    Pantić, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/178131.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic measurements
    scale model
    air absorption
    numerical compensation
    Opis:
    The absorption of sound in air represents one of the main problems of the scale model measurements. This absorption, especially at higher frequencies, is considerably greater than the value determined by the law of acoustical similarity between the full scale and the scale model. Different alternatives are applied for compensation of the excess air absorption including a numerical compensation. In this paper, a modified approach to numerical compensation is proposed. It is based on compensation of the sound decay only, and not background noise. As a consequence, there is no an increase of background noise in the compensated impulse response. The results obtained by the proposed procedure are compared to the corresponding ones obtained by the other procedures.
    Źródło:
    Archives of Acoustics; 2012, 37, 2; 219-225
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Perfect absorption for modulus-near-zero acoustic metamaterial in air or underwater at low-frequency
    Autorzy:
    Gaafer, Fatma Nafaa
    Powiązania:
    https://bibliotekanauki.pl/articles/2141684.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic metamaterial
    perfect absorption
    Fabry-Pérot resonances
    subwavelength scale
    modulus-near-zero
    Opis:
    We theoretically propose a method to achieve an optimum absorbing material through a modulus-near-zero (MNZ) metamaterial immersed in air or water with a change in slit width part. The destructive interference has paved the way to achieve perfect absorption (PA). Depending upon theoretical analysis, an acoustic metamaterial (AMMs) that supports resonance with a monopole (140 Hz) is developed to construct a low-frequency sound-absorbing technology. The dissipative loss effect can be by attentively controlling onto slit width to achieve perfect absorption. When there are thin slit width and visco-thermal losses in the structure, it is observed that they lead to high absorption. We use finite element simulations via COMSOL Multiphysics software to theoretical measurement in impedance tube and show the influence of structural parameters in both mediums. The results are of extraordinary correspondence at low frequency to achieve optimum perfect absorption (99%). That might support AMMs to actual engineering-related applications in the process of mitigating noise, slow sound trapping, notch filtering, energy conversion, and time reversal technology.
    Źródło:
    Archives of Acoustics; 2022, 47, 1; 25-31
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of the Effect of Non-Flat Surfaces on the Performance of Perforated Acoustic Absorber
    Autorzy:
    Hashemi, Zahra
    Fahim, Ali
    Monazzam, Mohammad Reza
    Powiązania:
    https://bibliotekanauki.pl/articles/31339869.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    perforated acoustic absorber
    surface shape
    statistical absorption coefficient
    reverberation chamber
    finite element method
    Opis:
    In order to investigate the effect of the surface shape on the performance of perforated panels, three non-flat shapes were considered for perforated panel with their absorption performance compared with the usual shape of the (flat) perforated panel. In order to simulate the absorption coefficient of a non-flat perforated panel, the finite element method was implemented by the COMSOL 5.3a software in the frequency domain. Numerical simulation results revealed that all the shapes defined in this paper improve the absorption coefficient at the mid and high frequencies. A and B shapes had a higher performance at frequencies above 800 Hz compared to the flat shape. Also, shape C had a relative superiority at all frequencies (1–2000 Hz) compared to the reference shape; this superiority is completely clear at frequencies above 800 Hz. The maximum absorption coefficient occurred within the 400–750 Hz range. After determining the best shape in terms of absorption coefficient (shape C), a perforated panel of 10 m2 using fiberglass fibers and desired structural properties was built, and then it was also subjected to a statistical absorption coefficient test in the reverberation chamber according to the standard. The results of the statistical absorption coefficient measurement showed that the highest absorption coefficient was 0.77 at the frequency of 160 Hz. Also, to compare the experimental and numerical results, these conditions were implemented in a numerical environment and the statistical absorption coefficient was calculated according to the existing relationships. A comparison of the numerical and laboratory results revealed acceptable agreement for these two methods in most frequency spectra, where the numerical method was able to predict this quantity with good accuracy.
    Źródło:
    Archives of Acoustics; 2023, 48, 3; 171-181
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sensitivity Analysis of Acoustic Field Parameters on a Change of Boundary Conditions in a Room
    Autorzy:
    Suder-Dębska, K.
    Czajka, I.
    Czechowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177639.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sensitivity analysis
    acoustic parameter
    geometrical method
    sound absorption coefficient
    noise of power machines
    Opis:
    The area of environmental protection concern minimises the impact that technical objects have on the environment. Usually the most effective way of protecting the environment is to influence the source of the problem. For this reason studies are conducted to modify the construction of machines, power machines in particular, so as to minimise their impact on the environment. In the case of environmental protection from noise it is most convenient to carry out measurements in an anechoic chamber. Unfortunately, this is possible only in very limited circumstances. In all other cases measurements are performed using an engineering method or the survey method, both of which are described in the standards and by taking into account the so-called environmental corrections. The obtained results are burdened with greater error than those of measurements in an anechoic chamber. Therefore, it would seem advantageous to develop a method of obtaining similar and reliable results as those in an anechoic chamber, but in a reverberant field. The authors decided to use numerical modelling for this purpose. The main objective of this work is a comprehensive analysis of the numerical model of a laboratory designed for acoustic tests of selected power machines. The geometry of a room comprising an area of analysis is easy to design. The main difficulty in modelling the phenomena occurring in the analysed area can be the lack of knowing the boundary conditions. Therefore, the authors made an attempt to analyse the sensitivity of various acoustic parameters in a room in order to change these boundary conditions depending on the sound absorption coefficient.
    Źródło:
    Archives of Acoustics; 2014, 39, 3; 343-350
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    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:
    Effect of the composite temperature and humidity test on the sound absorption coefficient of fibrous materials used in automotive applications
    Badanie wpływu starzenia materiału w wyniku działania temperatury i wilgotności na współczynnik pochłaniania dźwięku materiałów dźwiękochłonnych stosowanych w motoryzacji
    Autorzy:
    Białkowski, P.
    Zapart, Ł.
    Krężel, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/263246.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji
    Tematy:
    sound absorption coefficient
    absorber materials
    acoustic
    impedance tube
    współczynnik pochłaniania dźwięku
    materiały dźwiękochłonne
    akustyka
    rura impedancyjna
    Opis:
    In this article an attempt to determine the effect of composite temperature and humidity test on the sound absorption coefficient for commonly used materials in vehicles is described. Three types of fibrous materials were selected. The absorption coefficient was determined for material samples and then the materials were tested with composite temperature and humidity test. After the test, the sound absorption coefficient was measured again. The difference between the absorption coefficients before and after the test shows the actual effect on the sound absorption. An impedance tube was used to determine the absorption coefficient. Results are presented in graphs and tables for three types of fibrous materials. The method of measurement is described and conclusions are drawn.
    W pracy przedstawiono próbę określenia wpływu temperatury i wilgotności na współczynnik pochłaniania dźwięku materiałów powszechnie stosowanych w samochodach. Do badań wybrano trzy rodzaje materiału włóknistego. Dla próbek materiału wyznaczono współczynnik pochłaniania dźwięku, a następnie próbki te poddano złożonej próbie temperatury i wilgotności. Po wykonaniu testu temperaturowo- wilgotnościowego ponownie wyznaczono współczynnik pochłaniania dźwięku. Różnica pomiędzy współczynnikami pochłaniania przed i po teście przedstawia rzeczywisty wpływ temperatury i wilgotności dla danej próbki materiału. Do wyznaczenia współczynnika pochłaniania dźwięku wykorzystano rurę impedancyjną. Wyniki przedstawiono w formie wykresów i tabel dla danego materiału. Opisano przebieg pomiarów oraz powstałe wnioski.
    Źródło:
    Archiwum Motoryzacji; 2018, 81, 3; 29-38
    1234-754X
    2084-476X
    Pojawia się w:
    Archiwum Motoryzacji
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acoustic Panels Inspired by Nature
    Autorzy:
    Borkowski, Bartłomiej
    Suder-Dębska, Katarzyna
    Wiciak, Jerzy
    Szlachta, Anna Maria
    Powiązania:
    https://bibliotekanauki.pl/articles/1953507.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    acoustic panel
    absorption
    reflection
    design process
    lava cave
    glacier cave
    geometrical method
    3D modelling
    concept design
    Opis:
    The article presents the approach to the design process of acoustic panels based on the scientific research. This approach is based on combining the technical and the design competences to develop the innovative product value for the concept of acoustic panels. The article presents the concepts of two new acoustic panels – an absorbing and scattering panel and a panel reflecting sound waves. The first part of the article presents the starting point for the presented project – the acoustic research and the inspiration for both types of presented solutions. Next, the materials possible to use were discussed, which could reproduce the natural acoustic properties of the lava and glacier caves. The next part presents consecutive stages of the product development in a modern form, ensuring the expected acoustic properties. The last part of the article presents a fully functional solution and proposes further research and development directions.
    Źródło:
    Archives of Acoustics; 2021, 46, 1; 135-146
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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