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Wyświetlanie 1-15 z 34
Tytuł:
Fourier expansion solution for a switched shunt control applied to a duct
Rozwiązanie Fouriera dla przewodu akustycznego z bocznikującym układem sterowania
Autorzy:
Ameduri, S.
Ciminello, M.
Powiązania:
https://bibliotekanauki.pl/articles/280041.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
synchronised switched shunt control
piezoelectric
pressure sound level
Opis:
In the present work, a semi analytic approach aimed at estimating the effects on reduction of the pressure sound level by synchronised switched shunt logic is described. The displacement field within a 1D longitudinal air column through a Fourier series expansion has been formalised by assigning a sinusoidal perturbation and fluid-structure interface condition on the left and right boundaries, respectively. To simulate the no control operative condition, the solution has been computed for the entire time domain, keeping invariant all circuitry properties; then for the switch working modality, the solution has been computed by splitting the entire time domain into partitions; for any partition, specific circuitry properties (e.g. piezo voltage, electrical field...) have been selected. Based on the displacement information, the related sound pressure level has been compared for no controlled and controlled operative conditions, with and without signal amplification.
W pracy zaprezentowano pół-analityczne rozwiązanie zagadnienia redukcji poziomu ciśnienia akustycznego w przewodzie za pomocą zsynchronizowanej metody bocznikowania. Opis pola przemieszczeń wewnątrz jednowymiarowej kolumny powietrza sformalizowano rozwinięciem w szereg Fouriera przy uwzględnieniu sinusoidalnie zmiennych zaburzeń na prawym i lewym brzegu przewodu. Dla przypadku z wyłączonym układem sterowania rozwiązanie obliczono w całej dziedzinie czasu przy utrzymaniu stałych parametrów obwodu elektrycznego, natomiast dla trybu sterowanego dokonano analizy, dzieląc przedział czasu na fragmenty. W każdym z nich charakterystyczne cechy układu sterowania (np. napięcie przykładane do piezoelektryków, natężenie pola elektrycznego...) dobrano w odpowiedni sposób. Na podstawie obserwacji przemieszczeń porównano poziom ciśnienia akustycznego dla warunków z wyłączonym i włączonym sterowaniem oraz z i bez wzmocnienia sygnału.
Źródło:
Journal of Theoretical and Applied Mechanics; 2010, 48, 2; 479-504
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Acoustic Treatment on Music Teachers’ Exposure to Sound
Autorzy:
Kozłowski, E.
Młyński, R.
Powiązania:
https://bibliotekanauki.pl/articles/177728.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
music teachers
sound pressure level
acoustic treatment
Opis:
In this study, music teachers’ exposure to sound was tested by measuring the A-weighted equivalent sound pressure level (SPL), the A-weighted maximum SPL and the C-weighted peak SPL. Measurements were taken prior to and after acoustic treatment in four rooms during classes of trumpet, saxophone, French horn, trombone and percussion instruments. Results showed that acoustic treatment affects the exposure of music teachers to sound. Daily noise exposure levels (LEX, 8 h) for all teachers exceeded a limit of 85 dB while teaching music lessons prior to room treatment. It was found that the LEX, 8 h values ranged from 85.8 to 91.6 dB. The highest A-weighted maximum SPL and C-weighted peak SPL that music teachers were exposed to were observed with percussion instruments (LAmax = 110.4 dB and LCpeak = 138.0 dB). After the treatments, daily noise exposure level decreased by an average of 5.8, 3.2, 3.0, 4.2 and 4.5 dB, respectively, for the classes of trumpet, saxophone, French horn, trombone and drums, and did not exceed 85 dB in any case.
Źródło:
Archives of Acoustics; 2014, 39, 2; 159-163
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Technical Possibilities of Reducing the Sound Pressure Level Emitted into the Environment by a Power Transformer
Autorzy:
Borucki, S.
Boczar, T.
Cichoń, A.
Powiązania:
https://bibliotekanauki.pl/articles/177473.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
power transformer
corrected sound pressure level
noise
modernization
Opis:
The subject presented in this paper refers to measurements and assessment of the corrected sound pressure level values (noise) occurring around a medium-power transformer. The paper presents the values of noise accompanying the operation of the power object before and after its modernization, which consisted in repeated core pressing and replacement of the cooling system. The main aim of the research work was the assessment of the influence of the repair work on the noise level emitted into the environment.
Źródło:
Archives of Acoustics; 2011, 36, 1; 49-56
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Musician’s Earplugs on Sound Level and Spectrum During Musical Performances
Autorzy:
Kozłowski, E.
Żera, J.
Młyński, R.
Powiązania:
https://bibliotekanauki.pl/articles/90990.pdf
Data publikacji:
2011
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
earplugs
hearing protection
noise
sound pressure level
musicians
Opis:
In this study, change in A-weighted and 1/3-octave sound pressure levels (SPLs) was used to assess the influence of wearing earplugs by musicians on their musical performances. Seven soloists and 3 music assembles performed 4 pieces of music with musician’s earplugs donned and doffed. They used silicon custom moulded earplugs with acoustic filters designed to attenuate sound by 9, 15 or 25 dB. Results showed that the use of earplugs affected the sound level and the spectrum of played sounds. This effect was the greatest for brass players. The difference between SPLs in high-frequency 1/3-octave bands and A-weighted SPLs with and without earplugs exceeded 5 and 15 dB, respectively. Similar changes for woodwind, percussion and string instruments were less noticeable than for brass instruments; they were more than 5 dB for 1/3-octave spectra and no more than 2 dB for A-weighted SPL.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2011, 17, 3; 249-254
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Construction Changes in the Teeth of a Gear Transmission on Acoustic Properties
Autorzy:
Wieczorek, A.
Powiązania:
https://bibliotekanauki.pl/articles/90168.pdf
Data publikacji:
2012
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
gear
tooth height
gear contact ratio
sound pressure level
Opis:
This paper presents results of experimental research on the acoustic properties of gear wheels with high-profile teeth with differentiated tooth height. Those results showed that gear transmissions with high-profile teeth have the best acoustic properties, with the value of the transverse contact ratio εα ≈ 2.0. They also showed that a reduction in tooth height, and thereby in contact ratio, increased the sound pressure level.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2012, 18, 4; 499-507
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of noise transmission of a machine tool enclosure
Autorzy:
Bleicher, Friedrich
Reichl, Christoph
Linhardt, Felix
Wimberger, Peter
Habersohn, Christoph
Krall, Stephan
Powiązania:
https://bibliotekanauki.pl/articles/99968.pdf
Data publikacji:
2019
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
sound pressure level
machine enclosure
noise transmission
acoustic grid
Opis:
Machine tools are highly integrated mechatronic systems consisting of dedicated mechanic design and integrated electrical equipment – in particular drive systems and the CNC-control – to realize the complex relative motion of tool towards work piece. Beside the process related capabilities, like static and dynamic stiffness as well as accuracy behavior and deviation resistance against thermal influence, safety aspects are of major interest. The machine tool enclosure must fulfill multiple requirements like retention capabilities against the moving parts of broken tools, lose work pieces or clamping components. In regular use, the noise emission have to be inhibited at the greatest possible extent by the machine tool enclosure. Nevertheless, the loading door and the moving parts of the workspace envelope are interfaces where noise transmission is harder to be avoided and therefore local noise emissions increase. The aim of the objective investigation is to analyse the noise emission of machine tools to determine the local noise transmission of a machine tool enclosure by using arrays of microphones. By the use of this measuring method, outer surfaces at the front, the side and on the top of the enclosure have been scanned. The local transient acoustic pressures have been recorded using a standard noise source placed on the machine table. In addition, an exemplary manufacturing process has been performed to analyse the frequency dependent location resolved sound emissions.
Źródło:
Journal of Machine Engineering; 2019, 19, 3; 5-16
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and Optimization of Micro Speaker-Box Using a Passive Radiator in Portable Device
Autorzy:
Jiang, Y.-W.
Kwon, J.-H.
Kim, H.-K.
Hwang, S.-M.
Powiązania:
https://bibliotekanauki.pl/articles/176530.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
passive radiator
speaker box
SPL improvement
Sound Pressure Level
Opis:
With the rapid development of multimedia devices such as smart phones and tablet PCs, microspeakers have been recently increasingly used for audio equipment. Improving the acoustic performance of a microspeaker is always a main concern, especially in the low frequency range. To avoid sound cancelation, a microspeaker unit is usually inserted into a speaker box. A passive radiator is also used in speaker boxes to improve the sound performance in the loudspeaker system. However, passive radiators have not been applied into microspeaker system. In this study, a speaker box with a passive radiator was analyzed and optimized to achieve a higher Sound Pressure Level (SPL) in a microspeaker system. The Finite Element Method (FEM), two-degree-of-freedom (DOF) vibration theory, and a plane circular piston sound source were used to study the electromagnetic, vibration, and acoustic characteristics, respectively. Optimization was conducted by changing the mass, stiffness, and size of the passive radiator. Based on the optimized parameters, a new sample was manufactured. The experiment results show that the SPL of the optimized speaker box with a passive radiator is improved by 5 dB at 200 Hz compared with the one without a radiator. The analysis results also matched the experiment results.
Źródło:
Archives of Acoustics; 2017, 42, 4; 753-760
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Fast Method of Feature Extraction for Lowering Vehicle Pass-By Noise Based on Nonnegative Tucker3 Decomposition
Autorzy:
Wang, H.
Cheng, G.
Deng, G.
Li, X.
Li, H.
Huang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/177883.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vehicle pass-by noise
NTD
feature extraction
sound pressure level
Opis:
Usually, the judgement of one type fault of vehicle pass-by noise is difficult for engineers, especially when some significant features are disturbed by other interference noise, such as the squealing noise is almost simultaneous with the whistle in the exhaust system. In order to cope with this problem, a new method, with the antinoise ability of the algorithm on the condition by which the features are entangled, is developed to extract clear features for the fault analysis. In the proposed method, the nonnegative Tucker3 decomposition (NTD) with fast updating algorithm, signed as NTD_FUP, can find out the natural frequency of the parts/components from the exhaust system. Not only does the NTD_FUP extract clear features from the confused noise, but also it is superior to the traditional methods in practice. Then, an aluminium-foil alloy material, which is used for the heat shield for its lower noise radiation, replaces the aluminium alloy alone. Extensive experiments show that the sound pressure level of the vehicle pass-by noise is reduced 0.9 dB(A) by the improved heat shield, which is also considered as a more lightweight design for the exhaust system of an automobile.
Źródło:
Archives of Acoustics; 2017, 42, 4; 619-629
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Overview of the Noise Levels Measured in Industrial Facilities in Serbia and Implemented Methods of Protection
Autorzy:
Luburić, Uranija Kozmidis
Samardžić, Selena
Lakatoš, Robert
Mihailović, Aleksandra
Veselinović, Milka
Powiązania:
https://bibliotekanauki.pl/articles/176762.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
noise
industry
SPL
sound pressure level
frequency analysis
noise protection
Opis:
Noise is one of the most significant factors which not only disturbs working conditions, but has a large impact on workers’ health. This problem has existed in industries since the beginning and, despite technical and other solutions, it has not been solved. There is a large number of papers, supported with very detailed analyses, that investigate noise levels in industry or contain questionnaires about the impact of noise on workers’ overall health and work abilities. The purpose of this paper is to contribute to the global picture of sustainability and the development of strategies for improving the quality of working environment, with special attention to the generation of noise in different production processes in thirteen different industries in Novi Sad, Serbia. The paper also seeks to examine the advantages and drawbacks of the implemented protective methods and to provide some recommendations for their better implementation in order to contribute to solving this significant problem of today.
Źródło:
Archives of Acoustics; 2020, 45, 3; 499-510
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Urethane Foam Cushioning on Structure-Borne Sound Transfer by a Slab with Panel Flooring
Autorzy:
Mu, R.
Toyoda, M.
Takahashi, D.
Powiązania:
https://bibliotekanauki.pl/articles/176817.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
urethane foam
direct pasted flooring
floor impact sound
sound pressure level
sound insulation performance
Opis:
Urethane foam mattresses are commonly used as cushioning when placing panel flooring on the floor slab of a building. Urethane foam consists of elastic fibres with pores. Both elements can affect the performance of the insulation against impact sounds. However, these effects have not yet been detailed, and they may change if the material properties or constitution of the fibres and pores in the cushioning change. In this paper, we propose an analytical model for use in evaluating the performance of insulation against floor impact sound. This model was used to examine the contribution of the pores versus the elastic fibres to wave transmissions from the flooring surface to the slab. The results reveal that the constitution of the foam (either open or closed cells of pores) and the thickness and hardness of the cushion layer strongly affect the sound insulation performance of the floor.
Źródło:
Archives of Acoustics; 2016, 41, 1; 99-106
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of noise in tractor K700 cabin
Autorzy:
Pobedin, A. V.
Dolotov, A. A.
Iskaliev, A. I.
Potapov, P. V.
Powiązania:
https://bibliotekanauki.pl/articles/242604.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
capital repair
sound pressure level
noise total level
noise spectre
tractor
cabin
measuring
Opis:
This paper briefly describes method of noise-measuring tractor’s K700 cabin, obtained noise spectres were analysed and recommendations based on these results for noise decreasing in cabin K700 are proposed. Air noise penetrates into the tractor’s K700 cabin through panels, enclosures, apertures, chinks etc. Structural noise in the cabin is caused by vibrations transfer from sources along tractor frame through vibration isolators to cabin walls and carcass. At that, the main noise sources are engine case, air system, exhaust system, engine cooling system fan and also transmission case located under cabin floor. Every panel in the cabin has own intensity of sound waves radiation and thus contributes to forming of the sound field on the operator workspace. Therefore, it is important to know the sound pressure level near every panel into the cabin. It was state that at low frequencies, noise from left windshield prevails. In addition, in high frequencies bands the highest sound pressure issues from partition between engine area and cabin. Noise spectres have sound pressure peaks in bands with centre frequencies. Total noise level perceived by operator in tractor cabin is less during tractor motion on dirt road without aggregate than during its work with seeding machine on field prepared for winter grasp. At that, partition between engine area and cabin contributes greatly. Thus, for integrated noisiness, reducing in the tractor cabin sound isolation of partition between engine area and cabin should be increased and also sound isolation of windshields located closely to exhaust pipe has to be improved. To decrease low-frequency noise optimization of tractor cabin vibration isolation system need to be performed.
Źródło:
Journal of KONES; 2015, 22, 1; 261-264
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic Analysis Using Sound Level Meter to Determine the Period of Usage of the Spindle Bearing of a Radial Drilling Machine
Autorzy:
Charles, S.
Vijaya, Joslin D.
Powiązania:
https://bibliotekanauki.pl/articles/176769.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustical condition monitoring
radial drilling machine
spindle bearing
sound level meter
sound pressure level
sound muting transducer
Opis:
The condition monitoring techniques like acoustic emission, vibration analysis, and infrared thermography, used for the failure diagnosis of bearings, require longer processing time, as they have to per form acoustical measurement followed by signal processing and further analysis using special software. However, for any bearing, its period of usage can be easily determined within an hour, by measuring the bearing sound, using sound level meter (SLM). In this paper the acoustical analysis of the spindle Bering of a radial drilling machine was performed using SLM, by measuring the sound pressure level of the bearing in decibels, for different frequencies, while muting all the other noises. Then using an experimental set up, two database readings were taken, one for new bearing and the other for completely damaged bearing, both are SKF6207, which itself is the spindle bearing. From these three sets of sound pressure level readings, the period of usage of the spindle bearing, was calculated using an interpolation equation, by substituting the life of the bearing from the manufacturer’s catalogue. Therefore, for any machine with a SKF6207 bearing, its usage time can be estimated using the database readings and one measurement on that machine, all with the same speed.
Źródło:
Archives of Acoustics; 2019, 44, 3; 505-510
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
3D Multi-Domain MFS Analysis of Sound Pressure Level Reduction Between Connected Enclosures
Autorzy:
Godinho, L.
Branco, F. G.
Mendes P., A.
Powiązania:
https://bibliotekanauki.pl/articles/177013.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Method of Fundamental Solutions (MFS)
domain decomposition
closed spaces
sound pressure level reduction
Opis:
In this paper, the authors study the 3D propagation of sound waves between two closed spaces. The separation element between the two rooms is considered to include either a small opening or a homogeneous lightweight panel, coupling the two spaces. A numerical study of this configuration is performed, trying to understand the influence of the position and geometry of this opening in the sound pressure level reduction curve at low and midfrequencies. Additionally, the coupling effect between the two acoustic spaces is analyzed, in order to better understand its importance when determining the sound pressure level reduction. Different boundary conditions are ascribed to the walls of these rooms, simulating both the completely reflecting and partially absorbing surfaces. The numerical modelling was performed using a multi-domain formulation of the Method of Fundamental Solutions (MFS). The system is composed of two coupled rooms, limited by rigid or by absorbing walls, and separated by a thin wall (tending to null thickness) with a small opening. An experimental validation of the proposed model is presented, comparing its results with those found experimentally for a reduced-scale model. It is important to note that, for such a configuration, a traditional single-domain approach using methods like the MFS or the BEM would lead to undetermined equation systems, and thus the proposed model makes use of a domain decomposition technique.
Źródło:
Archives of Acoustics; 2011, 36, 3; 575-601
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hałas maszyn- znormalizowane metody wyznaczania poziomu ciśnienia akustycznego emisji
Autorzy:
Pleban, D.
Augustyńska, D.
Powiązania:
https://bibliotekanauki.pl/articles/180215.pdf
Data publikacji:
2000
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
hałas maszyn
normalizacja
poziom ciśnienia akustycznego emisji
machine noise
normalisation
sound pressure level
Źródło:
Bezpieczeństwo Pracy : nauka i praktyka; 2000, 10; 6-9
0137-7043
Pojawia się w:
Bezpieczeństwo Pracy : nauka i praktyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena emisji hałasu maszyn na podstawie poziomów ciśnienia akustycznego emisji
Assessment of noise emission of machines on the basis of emission sound pressure levels
Autorzy:
Pleban, D.
Powiązania:
https://bibliotekanauki.pl/articles/180112.pdf
Data publikacji:
2005
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
hałas
hałas maszyn
poziom ciśnienia akustycznego emisji
noise
machine noise
sound pressure level
Opis:
Zgodnie z dyrektywą europejską 98/37/EC dotyczącą maszyn poziomy ciśnienia akustycznego emisji powinny być uwzględnione podczas oceny akustycznej maszyny. Metody wyznaczania tych poziomów są określone w serii norm europejskich EN ISO 11200. W artykule przedstawiono wyniki badań eksperymentalnych dotyczących wyznaczania poziomów ciśnienia akustycznego emisji hałasu maszyn.
According to European Directive 98/37/EC relating to machinery, emission sound pressure levels must be taken into consideration while carrying out an acoustic assessment of machinery. The European Standard series EN ISO 11200 specifies methods for determining emission sound pressure levels. This paper presents the results of experimental tests concerning determination of the emission sound pressure levels of different machines.
Źródło:
Bezpieczeństwo Pracy : nauka i praktyka; 2005, 4; 6-9
0137-7043
Pojawia się w:
Bezpieczeństwo Pracy : nauka i praktyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 34

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