摘要 :
Community noise levels in Ilorin metropolis were measured and analyzed. The noise climate variation was observed to be a function of time due to an increase in population density and other sources of environmental noise. There is ...
展开
Community noise levels in Ilorin metropolis were measured and analyzed. The noise climate variation was observed to be a function of time due to an increase in population density and other sources of environmental noise. There is increase in the day and night noise levels with growth in population. The noise levels have increased by 2 to 13 dB(A) in the past 20 years in Ilorin metropolis. Statistical analysis shows that the noise level exposure differs significantly from one location to another. High noise levels occur in the daytime at road junctions, followed by commercial centers and passengers loading parks. The noise map developed from this study based on the noise descriptors L D, L N, L DN, TNI, and L NP reveals high noise level exposure at the center of the city where commercial activities and clustered buildings with high population density exist. The noise map provides enough information for technical controls and interim legislation against environmental noise pollution in the metropolis.
收起
摘要 :
Community noise levels in florin metropolis were measured and analyzed. The noise climate variation was observed to be a function of time due to an increase in population density and other sources of environmental noise. There is ...
展开
Community noise levels in florin metropolis were measured and analyzed. The noise climate variation was observed to be a function of time due to an increase in population density and other sources of environmental noise. There is increase in the day and night noise levels with growth in population. The noise levels have increased by 2 to 13 dB(A) in the past 20 years in florin metropolis. Statistical analysis shows that the noise level exposure differs significantly from one location to another. High noise levels occur in the daytime at road junctions, followed by commercial centers and passengers loading parks. The noise map developed from this study based on the noise descriptors L_D, L_N, L_(DN)/ TNI, and L_(DN) reveals high noise level exposure at the center of the city where commercial activities and clustered buildings with high population density exist. The noise map provides enough information for technical controls and interim legislation against environmental noise pollution in the metropolis.
收起
摘要 :
Environmental noise has been a major environmental nuisance in metropolitan cities. To achieve the goal of sustainable community, noise reduction is an important approach. Without systematic noise mapping, the spatio-temporal dist...
展开
Environmental noise has been a major environmental nuisance in metropolitan cities. To achieve the goal of sustainable community, noise reduction is an important approach. Without systematic noise mapping, the spatio-temporal distribution of noise variations is hard to capture. This study proposes a new methodology framework to combine statistical models and acoustic propagation for dynamic updates of 2D and 3D traffic noise maps by using a limited number of noise sensors in Taipei City based on multisource data including noise monitoring, vehicle detectors, meteorological data, road characteristics, and socio-demographic data. The hourly mean dif-ference between the predicted and measured noise level is within the range of-6.25 dBA to-4.46 dBA in the 2D noise model. For the 3D noise model, the hourly mean prediction error is within the range of 0.02 dBA to 1.93 dBA. Based on the WHO benchmark for excessive road traffic noise, we found at least 30% of inhabitants in Taipei City are exposed to levels exceeding 53 dBA Lden, and >25% are exposed to noise levels exceeding 45 dBA Lnight. The noise maps not only can help identify vulnerable communities to adopt proper approaches for noise reduction but also can remind the residents to take action to improve their quality of life.
收起
摘要 :
The environmental noise level represents one of the key factors of life quality in urban areas of modern cities. A continuous monitoring of the noise levels and the analysis of results have become a necessity when we discuss a pos...
展开
The environmental noise level represents one of the key factors of life quality in urban areas of modern cities. A continuous monitoring of the noise levels and the analysis of results have become a necessity when we discuss a possible recovery of those areas with high levels of noise pollution, and particularly, those zones which were designed for specific activities, e.g., areas around hospitals and schools. The city of Nis, Serbia, owing to the permanent long-term noise monitoring, possesses a database containing figures related to the noise levels at relevant locations in the city, which can serve as a basis for an analysis of the change of conditions, their tendencies in the future, and recognizing factors which influence the danger of noise pollution. The paper involves an analysis of the environmental noise level collected during the previous years.
收起
摘要 :
In this paper we suggest an alternative method for the analysis of low frequency noise of transistors based on measurements of phase noise of a test oscillator. This method is demonstrated by experimental results obtained with a s...
展开
In this paper we suggest an alternative method for the analysis of low frequency noise of transistors based on measurements of phase noise of a test oscillator. This method is demonstrated by experimental results obtained with a simple test oscillator with HEMT, and central frequency of 13.769 GHz. The main contribution to phase noise of the test oscillator comes from up conversion of transistor LF noise. This idea and the method can be used for the selection of transistors for high frequency application or for design of test circuit in RF IC manufacture.
收起
摘要 :
The purpose of this work is to identify the contribution of noise from external sources to the noise pollution generated by a factory, by comparing sound pressure levels measured in its surroundings and those calculated by noise m...
展开
The purpose of this work is to identify the contribution of noise from external sources to the noise pollution generated by a factory, by comparing sound pressure levels measured in its surroundings and those calculated by noise mapping. A metal-mechanical manufacturing plant was chosen and sound pressure levels were measured at discrete points along two rings around it, called receivers. The noise measurement data from the first ring were entered into the Sound Plan software to determine, through iteration, the factory's main noise sources. The software then used this information to calculate noise maps and sound pressure levels at the receiver's positions in the second ring. Finally, the contribution of noise from external sources to the overall noise generated by the factory was determined by comparing the noise measured in the second ring with the simulated data. The placement of partial barriers along some critically noisy walls was found to be effective in controlling nighttime noise, ensuring that the sound level limit for this type of neighborhood, which is established by technical standards for environmental noise as L_(cq ) = 60 dB (A), is not reached.
收起
摘要 :
Today the aviation industry is strongly exposed to criticism based on its impact on climate change. While this is a very important challenge, the industry and especially airports also have a second important challenge: noise impac...
展开
Today the aviation industry is strongly exposed to criticism based on its impact on climate change. While this is a very important challenge, the industry and especially airports also have a second important challenge: noise impact, which needs to be managed more strategically and proactively.This paper discusses the key factors that influence noise impact, looking at the influence of the evolution of passenger numbers and movements, the influence of the time slots used for these movements and the movements of the lowest noise class aircraft. It will also examine why the permissiblenoise curve currently under discussion is much larger than that of the 2009 noise register, the first definition by the Swiss aviation regulator of the foreseen noise impact of Geneva Airport. The paper will investigate to what extent Geneva Airport can influence the noise curves through openinghours and slot availability, as well as ways in which the airport might achieve the 20 per cent noise reduction announced in the aeronautical infrastructure sector plan of 2018. Finally, it will suggest a methodology to produce a forecast of noise impact based on key variables such as movementsduring specific hours of the day and the percentage of movements of aircraft of the lowest noise class.
收起
摘要 :
Evaluation and analysis of noise pollution levels have been carried out to determine the level of noise and its sources in Ilorin metropolis. Noise measurements have been done in the morning, at noon, in the evening, and at night ...
展开
Evaluation and analysis of noise pollution levels have been carried out to determine the level of noise and its sources in Ilorin metropolis. Noise measurements have been done in the morning, at noon, in the evening, and at night to determine noise pollution all over the city. The selected areas of study are commercial centers, road junctions/busy roads, passenger loading parks, and high-density and low-density residential areas. The road junctions had the highest noise pollution levels, followed by commercial centers. The results of this study show that the noise levels in Ilorin metropolis exceeded allowed values at 30 of 42 measurements points. There is a significant difference (P < 0.05) in the noise pollution levels and traffic noise index in all the locations. From the measured noise values, a map of noise pollution was developed for Ilorin. Many solutions proposed for noise abatement in the city are set out.
收起
摘要 :
Environmental noise in urban areas is known to cause functional abnormalities reflected in human health and behavior. In developing countries such as Brazil, public schools are exposed to high levels of noise due in part to poor i...
展开
Environmental noise in urban areas is known to cause functional abnormalities reflected in human health and behavior. In developing countries such as Brazil, public schools are exposed to high levels of noise due in part to poor infrastructure, especially with regard to noise attenuation. In schools exposed to noise levels above the limits specified by regulations and international guidelines, students and teachers are at greater risk of health problems, and performance may be compromised. In this study we evaluated the impact of environmental noise on children and teachers at three public schools (a kindergarten, an elementary school, and a high school) in a Northeast Brazilian metropolis, with emphasis on noise generated by street, above ground rail and air traffic. Environmental noise maps were generated and teachers were administered questionnaires focusing on the impact of noise pollution on health and performance. The study was intended to subsidize efforts at urban planning and public policy making by measuring actual noise levels and probing their possible effects. As shown by our results, public schools are in urgent need of noise attenuation measures, and enforcement of noise emission regulations for public transportation needs to be more emphatic.
收起
摘要 :
In recent years, acoustic pollution caused by noise has considerably increased in many countries. Particularly in Spain, the noisiest country in Europe. It is sometimes difficult to predict the noise levels that a new installation...
展开
In recent years, acoustic pollution caused by noise has considerably increased in many countries. Particularly in Spain, the noisiest country in Europe. It is sometimes difficult to predict the noise levels that a new installation or an expansion of industrial equipment will cause in the surroundings. This work introduces a new methodology for the prediction, evaluation, and analysis of industrial noise sources, as well as a novel tool for predicting and categorizing outdoor noise from its measurement at their sources. A Wastewater Treatment Plant (WWTP) has been used to demonstrate the applicability and validity of this methodology. The continuous level of acoustic pressure equivalent has been measured in different points of the plant using an integrating sound level meter. From these values, noise maps have been built to obtain detailed information of the industrial noise generated in the installation. Also, the typical frequency patterns of each type of source have been used for the calculation of source noise apportionments. To achieve this objective, several noise sources have been selected to provide information about their contribution to the industrial noise in the WWTP surrounding area. Finally, predictions have been validated using actual measurements. This methodology is a useful tool to predict personal exposure to noise and the impact on the environment. This information can be used, in particular, to propose mitigation actions.
收起
原文获取