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Influence of State of Alarm Caused by COVID-19 on Noise in the City Centre of Huelva (Spain)

Fortes Juan Carlos, Sánchez-Sánchez Rafael, Bolívar Juan Pedro

Archives of Acoustics

2022

Vol. 47, No. 2

285--291

At the beginning of the COVID-19 pandemic the government of Spain decreed the State of Alarm to confine the entire population at their homes, except for essential services. Therefore, the central objective of this study is to evaluate the implication of this situation for the environmental noise existing in the city of Huelva (Spain). This study demonstrates that during the state of alarm an average daily reduction of 3.4 dBA was noted, and in the central moments of the day these reductions reached up to 4.4 dBA, while from 10:00 to 12:00 pm the reduction was around 6.5 dBA. Nevertheless, there were two moments of day: 3:00 am (garbage collection, street cleaning and container disinfection), and 8:00 pm (daily applause for health professionals), when the noise during the pandemic was higher than before it. It is further shown that globally, the loudest events only decreased by about 3 dBA, while the global background noise decreased by 10 dBA during the alarm state. Regarding road traffic noise, it is verified that in addition to being reduced by about 4 dBA, traffic represents 6.7% of noisy events during the alarm state, while before it represented 13%.

Control and prediction protocol for bearing failure through spectral power density

Castilla-Gutiérrez Javier, Fortes Juan Carlos, Davila Jose Miguel

Eksploatacja i Niezawodność

2020

Vol. 22, no. 4

651--657

This paper aims to analyse the results of the comparative study of the characteristic frequencies, in terms of Power Spectral Density (PSD), generated by an SKF6322 bearing in a rotational blower. Among all the analysed frequencies, we have focused on the ones generated by the shaft rotation speed, the one on the blades and the ones of the SKF6322 bearing, such as the tracks, the cage and the balls. For this study, we followed the ISO 10816 criteria, both in the sampling part and in the data analysis, using the speed values in terms of PSD, which improves the results in both high and low frequencies. This study can be used to predict the performance of bearings and their future failure, determining the most decisive frequency, the one with the highest incidence and the relative influence of each one on the different positions and monitoring coordinate axes. This procedure can be applied to improve the predictive maintenance protocol in order to improve the performance, efficiency and reliability of the equipment with bearings in their systems.