Wyniki wyszukiwania - BazTech

1

Initial assumptions for the system of automatic detection and classification of aircraft noise events

Bukała Michał, Nowoświat Artur, Chyla Andrzej

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022208

EN

The present study undertakes the development and implementation of an algorithm for an automatic separation of acoustic events related to aircraft flights. The data are provided by noise monitoring stations operating as part of multi-point continuous noise measurement systems around small and medium-sized airports and helicopter landing sites in Poland. The article presents initial assumptions of the developed method based on the conclusions of the research. For this purpose, two different methods of airborne noise signal detection will be discussed. The first method is based on the analysis of the value of the changing rate of the signal being the difference between the value of the analysed sample and the value of the h-th previous sample of the recorded sound level time history. The second method uses a convolutional neural network operating on values recorded in 1/3-octave bands. The objective of the study is to examine the effectiveness and limitations of the selected methods on the collected representative input data.

2

Intelligent system of noise control of the technical condition of railroad tracks

Aliev Telman, Babayev Tofig, Alizada Tahir, Alibayli Elnur, Ahmedov Heybatulla

Transport Problems

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2021

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T. 16, z. 1

65--73

EN

It is shown that modern geometry cars, flaw detector cars and other track test cars provide reliable control of the technical condition of all hauls of the railroad track at “certain intervals of time”. Their number is limited and therefore “continuous monitoring” of all hauls is almost impossible. At the same time, in real life, due to the impact of various factors, such as seismic processes, certain changes take place even a day after control. The authors consider one option for continuous monitoring of the beginning of changes in the technical condition of the track using intelligent tools, which allow one, by analyzing the useful signal and the noise from the soil vibrations caused by the rolling stock, to create informative attributes for identifying the technical condition of the track. The application of traditional technologies of correlation and spectral analysis and other methods for this purpose does not allow ensuring adequacy of the control results. This paper proposes a technology for extracting and analyzing useful vibration signals, the noise of vibration signals and the relationship between them. The estimates of both correlation and spectral characteristics of the useful signal and the noise are used as the main carriers of diagnostic information. Due to the simplicity and the reliability of implementation of the proposed technical tools, they can be easily installed in one of the cars of all rolling stocks, providing control of the beginning of changes in the technical condition of the track during their movement in all hauls

3

Noise Monitoring, Mapping, and Modelling Studies – A Review

Alam Pervez, Ahmad Kafeel, Afsar Shakil S., Akhtar Nasim

Journal of Ecological Engineering

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2020

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Vol. 21, nr 4

82--93

EN

This paper reviews the literature on noise monitoring, noise mapping and noise modeling studies carried out in different countries by many researchers. The article reveals the current status of the noise-related studies and noise mapping studies. It was discovered that 90% of the noise monitoring studies were focused on the traffic noise, while the remaining 10% focused on the residential, commercial and industrial areas. Sometimes, there may be a necessity to analyze the sound pressure levels all over the place, or around a particular piece of land and machinery of industry. Researchers have used the noise monitoring data for the development of 2D and 3D noise maps which gives a clear picture of the noise level around the source of noise in X, Y, and Z direction. For taking a decision regarding the noise level for any development project, predicting the noise level is always necessary. The traffic noise models are generally used for the purpose of prediction. Early models are based on constant vehicle speed, later some models predicted the noise level for interrupting the traffic flow. For instance, the Stop and Go model can be used for the prediction of the noise level in an interrupted flow. Four such models were reviewed and compared in this article.

4

Monitoring of the Noise Emitted by Machine Tools in Industrial Conditions

Józwik J., Wac-Włodarczyk A., Michałowska J., Kłoczko M.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 1

83--93

EN

The paper presents an analysis of noise emitted by selected machine tools in a production hall (under industrial conditions). Noise monitoring is a fundamental task for maintaining workplaces which are safe and healthy. This paper presents the noise measurements obtained for several machine tools, performed in accordance with the PN ISO 230–5:2002 standard. The identification of noise sources and levels was conducted by means of the UNIT 352 measurement system for DMU 50, BGO-CNC/RV/R, FU 251, FW 801, FWC 25/H. Detection of noise sources in the tested machine tools allows to maintain safety of workers and effective means of noise reduction, which are highly significant from the perspective of minimising noise at various workstations. The method of performing noise measurements at workstations using specific machines is normalised, so that the results of such measurements for different machines could be compared. The test results were presented in the form of diagrams and tables. The results of the tests are concluded by a detailed recommendation for the CNC machine tool operators to use hearing protection when at work. The results showed that the level of noise at the operator’s workstation significantly exceeds the standard at certain machining parameters.

5

Monitoring hałasu środowiskowego

Żuchowski R., Nowoświat A., Dulak L.

Izolacje

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2016

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R. 21, nr 4

20--27

PL

W artykule przedstawiono zagadnienia związane z akustyką środowiskową. Omówiono stosowane oznaczenia i definicje, zagadnienia prawne oraz założenia przyjmowane podczas obliczania hałasu środowiskowego, w tym podczas tworzenia map akustycznych.

EN

The article presents certain environmental acoustics issues. It discusses the applied identifications and definitions, legal issues, and assumptions used for environmental noise calculations, including drafting of acoustic maps.

6

Tłumienie hałasu w zakresie częstotliwości słyszalnych powyżej 8 kHz przez nauszniki przeciwhałasowe

Młyński R., Kozłowski E.

Logistyka

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2015

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nr 5

1159--1164, CD1

PL

Celem niniejszej pracy było uzyskanie danych o tłumieniu dźwięku pięciu modeli powszechnie stosowanych nauszników przeciwhałasowych, w zakresie częstotliwości słyszalnych powyżej 8 kHz, czyli częstotliwości, które nie są standardowo rozpatrywane podczas badań ochronników słuchu. Dane takie mogą być wykorzystywane do oceny czy określony ochronnik słuchu w odpowiednim stopniu zabezpiecza słuch pracownika w pasmach tercjowych 10, 12,5 i 16 kHz. Badania przeprowadzono z użyciem dwóch metod badawczych: subiektywnej (z udziałem osób, polegającej na pomiarze progu słyszenia) oraz obiektywnej (z użyciem testera akustycznego). Tłumienie dźwięku zmierzone z udziałem osób w pasmach tercjowych z zakresu od 10 do 16 kHz, w zależności od modelu nauszników przeciwhałasowych przyjmuje wartości od 29 do 44 dB. Metoda obiektywna w większości przypadków daje wyniki zbliżone do wyników uzyskanych metodą subiektywną.

EN

The aim of this study was to obtain values of the sound attenuation with five commonly-usedearmuff models in the audible frequency range above 8 kHz, i.e. frequencies that are not usually considered during testing of hearing protection devices. Such data can be used to assess whether a specific hearing protector sufficiently protects employee hearing in one-third octave bands of 10, 12.5 and 16 kHz. Studies were conducted using two test methods: subjective (with the participation of subjects, involving the measurement of the threshold of hearing) and objective (using artificial test fixture). Sound attenuation measured with the participation of subjects in the one-third octave frequency bands ranging from 10 to 16 kHz, depending on the model of earmuffs ranges from 29 to 44 dB. Objective method, in most cases, gives a close approximation to the results obtained by subjective method.