scholarly journals Experimental Investigation of Influence of Acoustic Wave on Vapour Precipitation Process

2013 ◽  
Vol 3 (2) ◽  
pp. 408-412
Author(s):  
V. Vekteris ◽  
I. Tetsman ◽  
V. Moksin
Keyword(s):  
Experimental Investigation ◽  
Acoustic Wave ◽  
Sound Field ◽  
Sound Level ◽  
Precipitation Process ◽  
Frequency Interval ◽  
Cleaning Efficiency ◽  
Air Cleaning ◽  
Cleaning Equipment ◽  
Measurement Results

The measurement results of acoustic field parameters above electroplating bath, in presence of water vapour, are analyzed in this work. Suction was created by means of side exhausters. It is obtained that the sound field generator generated a sound level of 130–140 dB at frequency interval between 1 and 10 kHz. It is shown that aerosol coagulation and precipitation processes are intensified under the mentioned conditions. The concentration of vapour and other aerosols in removal air decreases as a result, therefore air cleaning equipment costs can be reduced and cleaning efficiency increased.

scholarly journals Analysis of the Dependence of the Apparent Sound Reduction Index on Excitation Noise Parameters

2020 ◽  
Vol 10 (23) ◽  
pp. 8557
Author(s):  
Ervin Lumnitzer ◽  
Miriam Andrejiova ◽  
Anna Yehorova
Keyword(s):  
Low Frequency ◽  
Sound Field ◽  
Acoustic Properties ◽  
Diffusion Field ◽  
Frequency Interval ◽  
Technical Standards ◽  
Noise Type ◽  
Measurement Results ◽  
Partition Structure ◽  
Sound Reduction

In acoustic practice, established methods of measuring the acoustic properties of partition structures are used. Recommended procedures and means can be found in technical standards, but practice suggests that measurement results may also depend on measurement conditions. These procedures leave the choice of noise type, frequency interval examined, and excitation interval on the measurer. The aim of this research is to determine which parameter has a significant effect on the results, and to quantify the extent of this effect. We examined the type of noise, the frequency band of the sound passing through the partition structure and the excitation interval of the diffusion field in the rooms (hereinafter referred to as “excitation interval”). During the research, we conducted a number of repeated, statistically significant measurements, which we first evaluated by classical methods used in acoustic practice. We subjected the obtained results to a thorough mathematical analysis. Evaluation of the results shows that some measurement conditions significantly affect the resulting values, especially in the low-frequency spectrum. One of the most important elements which has an effect on the results is the type of excitation noise, which, when assessed in the source room, excites the diffuse sound field, and its transmission through the considered partition structure is measured. The significance of the investigated frequency interval was also demonstrated.

Noise Exposure Associated With Hearing Aid Use in Industry

1996 ◽  
Vol 39 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Thomas G. Dolan ◽  
James F. Maurer
Keyword(s):  
Hearing Aids ◽  
Noise Exposure ◽  
Hearing Aid ◽  
Sound Field ◽  
High Gain ◽  
Sound Level ◽  
Weighted Averages ◽  
Hearing Aid Use ◽  
Listening Environments ◽  
Level Meter

Although noise may be innocuous in many vocational environments, there is a growing concern in industry that it can reach hazardous levels when amplified by hearing aids. This study examined the daily noise exposures associated with hearing aid use in industry. This was done by both laboratory and site measurements in which hearing aids were coupled to the microphone of an integrating sound level meter or dosimeter. The former method involved the use of recorded railroad and manufacturing noise and a Bruel and Kjaer 4128 Head and Torso simulator. In the latter procedure, a worker wore one of three hearing aids coupled to a dosimeter during 8-hour shifts in a manufacturing plant. Both methods demonstrated that even when amplified by mild-gain hearing aids, noise exposures rose from time-weighted averages near 80 dBA to well above the OSHA maximum of 90 dBA. The OSHA maximum was also exceeded when moderate and high gain instruments were worn in non-occupational listening environments. The results suggest that current OSHA regulations that limit noise exposure in sound field are inappropriate for hearing aid users.

Finite element sound field analysis on measurement of absorption coefficient in a reverberation room -Relationships between inclination of walls and measurement results-

2021 ◽  
Vol 263 (1) ◽  
pp. 5571-5577
Author(s):  
Reiji Tomiku ◽  
Noriko Okamoto ◽  
Toru Otsuru ◽  
Shun Iwamoto ◽  
Shoma Suzuki
Keyword(s):  
Finite Element ◽  
Absorption Coefficient ◽  
Sound Field ◽  
Field Analysis ◽  
Reverberation Time ◽  
Absorption Coefficients ◽  
Sound Fields ◽  
Measurement Results ◽  
Coefficient Measurement ◽  
Absorption Performance

The absorption coefficients in a reverberation room are most representative measure for evaluating absorption performance of architectural materials. However, it is well known that measurement results of the coefficient vary according to a room shape of the measurement and area of the specimen. Numerical analyses based on wave acoustics are effective tools to investigate these factors on absorption coefficient measurement in reverberation room. In this study, sound fields for the measurement of absorption coefficient in reverberation room are analyzed by time domain finite element method (TDFEM). This study shows effectiveness of the analysis for investigation on causes of variation in the measurement results and improvement methods of the measurement. First, some measurement sound fields for absorption coefficient in reverberation rooms the walls of which are incline or decline are analyzed by the TDFEM. Next, reverberation times in each sound fields are calculated from the results obtained by TDFEM and the absorption coefficients are evaluated from the reverberation time of the room with and without specimen. Finally, the relationships among room shape, degree of inclination of the wall, the sound absorption coefficient of the specimen, frequencies and the measurement absorption coefficient are investigated.

Sound influence on spa park perception in feelings of visitors

2017 ◽  
Author(s):  
Małgorzata Sztubecka ◽  
Maria Mrówczyńska ◽  
Anna Bazan-Krzywoszańska ◽  
Marta Skiba
Keyword(s):  
Human Perception ◽  
Special Kind ◽  
Sound Level ◽  
Health Resort ◽  
Measurement Results ◽  
Noise Measurements ◽  
Permissible Levels ◽  
The One ◽  
The Impact

Noise can have many harmful effects on the recipients, however people exposed to noise on a long-term and regular basis can get used to it, even if the permissible levels are exceeded. In cities, green areas and park systems are provided to create a climate for rest and relaxation. Spa parks are a special kind of such park systems, which – in addition to the above-mentioned features – support therapies offered by spa facilities located there. On the one hand, patients and visitors appreciate various social and entertainment events held there, but – on the other – a multitude of sounds associated with them may reduce the comfort of their stay. The aim of this paper is to analyse the relationship between the results of noise measurements and the human perception of noise within the impact zone. The examined area is a spa park in the health resort district of Inowrocław, where seasonal measurements (taken in summer and winter) provided a basis for the determination of the connection between the measured values of equivalent sound level and the noise level perceived by surveyed people. A statistical analysis was performed to take into account the correlation between the obtained measurement results and the human perception of noise. It shows some differences in the perception of heard sounds. The results allow an evaluation of the soundscape of the analysed area.

scholarly journals Experimental investigations of the performance of a thermoacoustic electricity generator

2019 ◽  
Vol 116 ◽  
pp. 00025
Author(s):  
Ahmed Hamood ◽  
Artur Jaworski
Keyword(s):  
Experimental Investigation ◽  
Acoustic Wave ◽  
Load Resistance ◽  
Experimental Investigations ◽  
The Novel ◽  
Working Medium ◽  
Linear Alternator ◽  
Mean Pressure ◽  
Set Up ◽  
Working Parameters

This paper presents the experimental investigation of a two-stage thermoacoustic electricity generator able to convert heat at the temperature of the exhaust gases of an internal combustion into useful electricity. The novel configuration is one wavelength and consists of two identical stages. The identical stages will have out of phase acoustic wave at similar amplitudes which allows coupling a linear alternator to run in push-pull mode. The experimental set-up is 16.1 m long and runs at 54.7 Hz. The working medium is helium at 28 bar. The maximum generated electric power is 73.3 W at 5.64% thermal-to-electric efficiency. The working parameters including load resistance, mean pressure and heating power were investigated.

Evaluation of Noise Characteristics of Drainage and Water Supply Systems in Apartment Bathrooms

2014 ◽  
Vol 1025-1026 ◽  
pp. 987-990
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim ◽  
Kwan Seop Yang ◽  
Byung Kwon Lee
Keyword(s):  
Water Supply ◽  
Noise Level ◽  
Drainage System ◽  
Low Noise ◽  
Sound Level ◽  
Water Supply Systems ◽  
Apartment Building ◽  
Noise Characteristics ◽  
Measurement Results ◽  
Supply Systems

We have developed a low-noise drainage system, which was installed in bathrooms of apartment building units as well as in a mock-up test building, to evaluate the noise level in order to reduce the noise produced in the bathrooms of multiunit dwellings. The drainage system installed in the mock-up building consists of six types of detachable drains, and the level of noise produced during toilet use in the upper unit was measured in the lower unit. The measurement results showed that low-noise drainage 4 exhibited the Leq(equivalent continuous sound level) at 34.7 dB(A). The noise measurement results of various types of low-noise drains installed in an apartment building showed that the Leqduring toilet use was 46.7 dB(A) on average, and the Leqduring sink use was 40.5 dB(A) on average.

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