In this study, noise pollution assessments were performed along Marechal Deodoro Avenue and Batel Avenue, which are two major thoroughfares in the city of Curitiba, Brazil. Eleven points were evaluated at Batel Avenue...In this study, noise pollution assessments were performed along Marechal Deodoro Avenue and Batel Avenue, which are two major thoroughfares in the city of Curitiba, Brazil. Eleven points were evaluated at Batel Avenue and 16 points at Marechal Deodoro Avenue. The results of the noise level measurements and the calculation of noise maps indicated that both thoroughfares are acoustically polluted. The simulated and measured noise levels, in the 27 evaluated points, exceed the limits established by law 10,625 of the city of Curitiba, which establishes acceptable levels for the comfort of the population in the external environment. With regard to the traffic composition in the areas under study, the vehicle flow was found to consist mostly of light vehicles, representing 88% of the total flow along Batel Avenue and 85% on Marshal Deodoro Street. Based on the noise maps and measured noise levels, it was found that the entire length of Marshal Deodoro Avenue and Batel Avenue are strongly affected by street noise, which is readily explained by the constant traffic, high vehicle flow (number of vehicles/hour) and high vehicle speed at some points of these thoroughfares.展开更多
为了从复杂的轴承振动信号中提取微弱的故障信息,提出了一种基于局部均值分解(local mean decomposition,LMD)和奇异值差分谱的轴承故障诊断方法。首先通过LMD将非平稳的原始轴承故障信号分解为若干个PF(product function)分量,由于背...为了从复杂的轴承振动信号中提取微弱的故障信息,提出了一种基于局部均值分解(local mean decomposition,LMD)和奇异值差分谱的轴承故障诊断方法。首先通过LMD将非平稳的原始轴承故障信号分解为若干个PF(product function)分量,由于背景噪声的影响,难以从PF分量准确得到故障频率,对PF分量进行Hankel矩阵重构和奇异值分解,相应的得到奇异值差分谱,根据奇异值差分谱理论对某个PF分量进行消噪和重构,然后再求重构后PF分量的包络谱,便能准确地得到故障频率。仿真分析和滚动轴承内圈故障实例很好地验证了提出的改进方法的有效性。展开更多
This paper describes an analysis of the sound pressure levels at the exterior façade and inside the Hospital de Clínicas of the Federal University of Paraná. Measurements were taken at a total of ...This paper describes an analysis of the sound pressure levels at the exterior façade and inside the Hospital de Clínicas of the Federal University of Paraná. Measurements were taken at a total of 45 points, 24 at the exterior facade and 21 points inside the hospital on all the floors of the main building and in the maternity building. These 45 measurements were used to calculate the acoustic map of the hospital, which is located on General Carneiro Street, in the city of Curitiba, state of Paraná, Brazil. A comparison of the measured outdoor sound pressure levels against those established by Curitiba Municipal Law No. 10625 revealed that they all exceeded the daytime limit of 55 dB(A) permitted for areas around hospitals. The indoor sound pressure measurements and the noise levels for acoustic comfort established by the Brazilian technical standard ABNT NBR 10152 were compared, indicating that all the measured points, including those in the neonatal intensive care unit, exceeded the established limit of 35 dB(A) to 45 dB(A).展开更多
Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measur...Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measurement technique which makes sound visible in order to introduce further specific technical measures is advantageous. The question is if the time dependence of the signal got from such a non touching and non destructive acoustic method has the potential to calculate the materials damping from. Using a small sound source localization system (Microflown^TM probe), specimens of magnesium alloys with different grain sizes obtained by hydrostatic extrusion were investigated. It has been demonstrated that the fine grained microstructure led to a lower damping and its dependence on the strain was reduced. In this context, acoustic measurements by a sound source localisation system which makes materials characterization possible could be used as a quality tool to detect changes in highly stressed components. This approach allows to promote a selective substitution of conventional materials by more innovative ones. The offshore sector is considered to be a field of application: Wind turbines produce noise emission which stems mainly from turbulences at the tips of the rotor blades and vibrations of components inside the nacelle (e.9. gearbox, generator, ...). If the vibration amplitudes are too high, microcracks of components can lead to failure over the long term. The monitoring of microstructural changes using a larger type of a sound source localisation system is considered as an innovative technical approach with respect to maintenance activities.展开更多
文摘In this study, noise pollution assessments were performed along Marechal Deodoro Avenue and Batel Avenue, which are two major thoroughfares in the city of Curitiba, Brazil. Eleven points were evaluated at Batel Avenue and 16 points at Marechal Deodoro Avenue. The results of the noise level measurements and the calculation of noise maps indicated that both thoroughfares are acoustically polluted. The simulated and measured noise levels, in the 27 evaluated points, exceed the limits established by law 10,625 of the city of Curitiba, which establishes acceptable levels for the comfort of the population in the external environment. With regard to the traffic composition in the areas under study, the vehicle flow was found to consist mostly of light vehicles, representing 88% of the total flow along Batel Avenue and 85% on Marshal Deodoro Street. Based on the noise maps and measured noise levels, it was found that the entire length of Marshal Deodoro Avenue and Batel Avenue are strongly affected by street noise, which is readily explained by the constant traffic, high vehicle flow (number of vehicles/hour) and high vehicle speed at some points of these thoroughfares.
文摘为了从复杂的轴承振动信号中提取微弱的故障信息,提出了一种基于局部均值分解(local mean decomposition,LMD)和奇异值差分谱的轴承故障诊断方法。首先通过LMD将非平稳的原始轴承故障信号分解为若干个PF(product function)分量,由于背景噪声的影响,难以从PF分量准确得到故障频率,对PF分量进行Hankel矩阵重构和奇异值分解,相应的得到奇异值差分谱,根据奇异值差分谱理论对某个PF分量进行消噪和重构,然后再求重构后PF分量的包络谱,便能准确地得到故障频率。仿真分析和滚动轴承内圈故障实例很好地验证了提出的改进方法的有效性。
文摘This paper describes an analysis of the sound pressure levels at the exterior façade and inside the Hospital de Clínicas of the Federal University of Paraná. Measurements were taken at a total of 45 points, 24 at the exterior facade and 21 points inside the hospital on all the floors of the main building and in the maternity building. These 45 measurements were used to calculate the acoustic map of the hospital, which is located on General Carneiro Street, in the city of Curitiba, state of Paraná, Brazil. A comparison of the measured outdoor sound pressure levels against those established by Curitiba Municipal Law No. 10625 revealed that they all exceeded the daytime limit of 55 dB(A) permitted for areas around hospitals. The indoor sound pressure measurements and the noise levels for acoustic comfort established by the Brazilian technical standard ABNT NBR 10152 were compared, indicating that all the measured points, including those in the neonatal intensive care unit, exceeded the established limit of 35 dB(A) to 45 dB(A).
文摘Noise measurements are especially a problem when the object under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measurement technique which makes sound visible in order to introduce further specific technical measures is advantageous. The question is if the time dependence of the signal got from such a non touching and non destructive acoustic method has the potential to calculate the materials damping from. Using a small sound source localization system (Microflown^TM probe), specimens of magnesium alloys with different grain sizes obtained by hydrostatic extrusion were investigated. It has been demonstrated that the fine grained microstructure led to a lower damping and its dependence on the strain was reduced. In this context, acoustic measurements by a sound source localisation system which makes materials characterization possible could be used as a quality tool to detect changes in highly stressed components. This approach allows to promote a selective substitution of conventional materials by more innovative ones. The offshore sector is considered to be a field of application: Wind turbines produce noise emission which stems mainly from turbulences at the tips of the rotor blades and vibrations of components inside the nacelle (e.9. gearbox, generator, ...). If the vibration amplitudes are too high, microcracks of components can lead to failure over the long term. The monitoring of microstructural changes using a larger type of a sound source localisation system is considered as an innovative technical approach with respect to maintenance activities.