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Calculation of noise maps around electrical energy substations
Abstract
This work is aimed at studying the noise caused by the transformers found in electrical substations located in calm areas in the city of Curitiba, Brazil. Although the level itself reaching the nearby buildings is not high if compared to other noise sources commonly found in a large city, they produce an annoying noise due to its low frequency tonal components. Two substations and their surroundings have been analyzed and acoustically mapped. The results have shown that some houses receive up to 35 dB(A) near one of the substations, which may led to some discomfort. It has also been noticed that a good planning of a substation, mainly of the firewalls, may help putting the houses under acoustical shadows.
... The noise source can be summarized as follows. Some noise was increasing in resident live place, and another coming mainly from traffic, but with some noise was occurred by man-made components [1] [2] [3]. Especially, some other noise sources are also important as they act within very closely areas in a city. ...
... where f is the operating frequency (Hz), Bm is the magnetic flux (T), δ is the stacking factor 0.96, and V/N is voltage per turn ratio. Table 1 Some common noise levels [1] [2] ...
... Jet take-off (20m) and threshold of pain Fig. 1. Typical noise spectrum of a transformer [1] [2]. Table 2 Typical noise spectrum of a transformer obtained by Rodrigues [1] [2] Frequency (Hz) ...
This paper characterizes the noise impact due to power transformer setup over the population living in the vicinity area. In order to reduce the noise level caused from the transformer, certain improvement on the electromagnetic design and mechanical structure are introduced. The noise effect from the transformer can be investigated with the simulation of acoustical mapping along with the on-site measurements. In this paper, an extreme low noise power transformer is designed and implemented. The designed power transformer with the capacity of 20MVA is installed in the Kiama city, Austria. To evaluate the real noise level in the neighborhood of the transformer, noise levels are measured and analyzed. According to the standard of comfortable living, the designed low-noise power transformer indeed provides the low noise level as desire.
... Noise measurements help you determine the environmental impact of your business [28][29][30]. The methodology to assess the environmental noise emitted into the environment is given in in the instructions no 308 and 338 Institute of Building Technology and State Inspectorate for Environmental Protection "Methods of measurement of external noise in the environment" [32] as well as in PN ISO 1996 -1,2, 3 [33][34][35] and PN-ISO 9613-1.2 ...
The aim of the study was the analysis of acoustic climate around the Municipal Sewage Treatment Plant in Lask. In the analysis, using computer program HPZ_2001 ITB, the calculations on the impact of the acoustic climate were carried out. In addition, to verify the calculations, current noise emission measurements during the operation of the wastewater treatment plant were made. The results found that during operation, the wastewater treatment plant does not teach exceeded permissible noise levels in adjacent areas under acoustic protection, both during the day and night.
... 2003;Diniz and Zannin, 2004;Alves et.al. 2004;Diniz and Zannin, 2005;Paz et.al., 2005;Coensel et.al., 2005;Gündogdu et.al., 2005;Tansatcha et.al., 2005). ...
Acoustic comfort is increasingly necessary in view of rising levels of noise pollution, especially in medium-sized towns and large cities. According to the WHO, noise pollution today is the type of pollution that affects the largest number of people in the world, second only to air and water pollution. Urban growth, along with the ever increasing number of circulating vehicles, greatly contributes to the higher levels of urban noise emission. Inhabitants of large cities all around the globe complain about noise, reporting irritability, rising blood pressure, headaches, sleep disorders, stress, etc. Considering that traffic and neighborhood noises (neighbors, construction work, religious buildings, commercial, cultural, and leisure activities) disturb people in their homes, it is conceivable that the sound insulation provided by façades and walls are inadequate, resulting in poor acoustic comfort. This chapter analyzes the acoustic performance of building materials with respect to their insulative properties. This performance is evaluated through in situ measurements of sound insulation, or alternatively, by computational simulation. This alternative is presented through real case studies in homes. The values found are compared with the limits set by International Standards for acoustic comfort. Techniques for measuring parameters that characterize building materials for acoustic comfort are presented and discussed. This chapter therefore offers an overview of building acoustics and acoustic performance of materials. The advantages and disadvantages of each of these approaches are discussed, as are technical standards in different countries.
... Therefore, it is important to monitor the industrial noise on a regular basis and to maintain the industrial noise level within the permissible limit to protect the health of the industrial workers. Many field surveys have been conducted to evaluate the outdoor noise environment in several countries [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The researchers and society in general are increasingly concerned about the issue of noise pollution and there has been a surge for the development of research in this area and the creation of laws and regulations and their proper enforcement to mitigate the impact of these disagreeable noises in the social environment, emphasizing about the fight against this current and harmful type of pollution [26][27][28][29][30][31][32] . ...
... Noise pollution in small, medium and large cities is an ever growing problem due to the fact that the urban environment is becoming increasingly crowded and busy. Many field surveys were conducted to evaluate the outdoor noise environment in several countries [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. ...
The paper describes a study of noise emission levels by roads inside an urban setting. For this purpose simultaneous measurements were performed: a) noise levels Leq, L10 and L90, b) vehicle flow and c) traffic composition. Vehicle flow and traffic composition have been used to estimate sound emission levels using mathematical models. Models were developed for two different situations, either as a function of a single variable (vehicle flow, VF), or as a function of two variables (VF and percentage of heavy vehicles, HV). Results of the prediction models agreed well with measured noise levels, especially for the model considering the two independent variables, VF and HV.
... Noise pollution in small, medium and large cities is an ever growing problem due to the fact that the urban environment is becoming increasingly crowded and busy. Many field surveys were conducted to evaluate the outdoor noise environment in several countries [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. ...
... I N RECENT years, more and more attention has been paid to the improvement of living quality in urban areas. Therefore, reduction of noise for power transformers setup in substations becomes critical [1], [2]. The noise mainly originates from energizing the core of transformers. ...
This paper presents the reduction of noise and vibration concerning the magnetostriction effects for a single-phase power transformer with a large capacity of 200 MVA. Two magnetic core shapes are investigated: 1) D-yoked core and 2) square-yoked core. The D-yoked core is used for the construction of the transformer prototype in this paper. The magnetostriction and the hysteresis loop of the core material are measured for the simulation and analysis of noise and vibration. The transformer prototype is assembled with an external clamping force applied on the core, and the core vibration and sound-level are observed. The transformer operates with a periodic excitation that may induce resonance in the core. To avoid this, a finite-element analysis is used for modal analysis to identify the natural frequencies of the core. A tank is also designed with a sufficiently rigid structure to avoid resonances. The sound-level of the fully assembled transformer prototype is measured, and it is found to have a low-noise level below 65 dB.
... The measured data serve as an input for the estimation of the noise curves through an interpolation process [1,2]. The second methodology consists in the implementation of one or several calculation methods that predict the noise levels based on the type of sources and the environment [3,4]. ...
This paper presents an evaluation of the German standard RLS 90 (Richtlinien für den Lärmschutz an Straben) for the estimation of noise levels produced by the traffic flow in Colombian conditions. For this, environmental noise measurements and relevant information required to simulate road noise were taken in two different areas of the City of Medellín. From the collected data, simulations were performed using the commercial package SoundPLAN. The influence of the input data on the accuracy of the noise levels was assessed by means of the total expanded uncertainty of the noise maps. Furthermore, RLS 90 was compared with an alternative approach based on interpolation methods. The results indicate that the use of RLS 90 allows noise levels to be predicted with good precision in areas where road noise predominates. Compared to the interpolation approach, it lets greater accuracy in the output data. Lastly, regarding the input data, the outcomes suggest that the variables related to the source characterization have the highest impact in the uncertainty of the simulation.
... a tradução de " soundscape" para "paisagens sonoras" foi feita na versão em português do livro "O Ouvido Pensante", publicado em 1997. No entanto, é no livro " The Tuning of the World " (A Afinação do Mundo), publicado em 1977 originalmente e em 2001 na versão portuguesa, é que Schafer define amplamente o conceito de paisagens sonoras (soundscape). ZANNIN, 2005). Vale destacar também que foram apresentados nesta pesquisa de percepção outros dados importantes como, por exemplo, as reações que o ruído traz, onde mais do que a metade indicou se sentir irritado (58%), seguido de baixa concentração (42%), insônia 20% e dores de cabeça (20 %). De modo geral, pode-se dividir em três grupos principais ...
Orientador : Paulo Henrique Trombeta Zannin Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Mecânica. Defesa: Curitiba, 2007 Inclui bibliografia
This chapter analyzes the impact of environmental noise generated by a paper mill on its surroundings, based on equivalent noise level measurements and noise mapping. Noise maps are used to simulate noise control solutions at the noise sources. After simulating the effect of the adoption of noise control measures, new simulations of the noise levels reaching the town adjacent to the paper mill confirm the efficacy of the proposed noise control measures. Noise maps are helpful in investment planning because they allow for budgetary control, i.e., prioritization of the most critical actions that will actually be effective in controlling industrial noise that impacts surrounding communities.
Minimizing the audible noise impact of a power system is one of the major measures for a cleaner power supply. In this study, a smart silencing unit was designed based on the universal design principles to mitigate the noise pollution of a substation. The corresponding large noise reduction coefficient (NRC), smart selective absorption characteristics at certain frequency bands, and a beneficial low-frequency sound absorption effect were verified through impedance tube and reverberation room tests. A comparison of the analysis results showed that after the installation of the smart silencing units, the average steady state maximal sound pressure level (SPL) acting on the surrounding community building surfaces decreased by 10.77 dB. Thus the substation audible noise impact of the substation on the ambient environment was properly limited. This innovative solution bridges the gaps between the acoustic absorption and insulation theory research field and the implementation of noise suppressing measures for an acoustic environment friendly substation. Consequently, a cleaner power supply and soundscape compatibility between the substation and surrounding communities can be achieved more readily.
This chapter presents a methodology for the assessment of environmental noise generated by heavy traffic on a highway running through an urban area of a Brazilian metropolis with a population of approximately 1.8 million. The noise pollution assessment was based on extensive field measurements of equivalent sound pressure levels and the subsequent calculation of noise maps. The noise maps were calculated based on heavy vehicle counts, road conditions, and average speed of vehicle traffic. The noise levels recorded on this road exceed the levels recommended by current legislation. This study demonstrates that taking only one control measure does not suffice to counteract noise efficiently. Instead, a plan involving various measures taken jointly is needed to effectively mitigate the problem.
This chapter analyzes the impact of environmental noise generated by a paper mill on its surroundings, based on equivalent noise level measurements and noise mapping. Noise maps are used to simulate noise control solutions at the noise sources. After simulating the effect of the adoption of noise control measures, new simulations of the noise levels reaching the town adjacent to the paper mill confirm the efficacy of the proposed noise control measures. Noise maps are helpful in investment planning because they allow for budgetary control, i.e., prioritization of the most critical actions that will actually be effective in controlling industrial noise that impacts surrounding communities.
Urban and industrial noise pollution is present in virtually every country in the world. Noise pollution studies are therefore needed to find solutions to improve the quality of life in cities.
The analyses described in the 18 chapters of this book are based on field measurements of sound pressure levels and computer calculations of noise maps. Noise mapping is a highly effective technique to visualize the problem of noise in large urban centers and noise generated by manufacturing plants. This technique facilitates the search for answers to the problem of noise pollution and is helpful for comparing solutions, enabling one to select the most effective and economically feasible solution. Several case studies are described throughout the book. These are examples of real cases, which were used to assess the quality of urban and industrial environments. Based on measurements, noise maps are calculated to show the current situation of noise pollution. Subsequent analyses based on noise mapping simulations indicate the urban and industrial noise abatement measures recommended for the cases in question.
The first chapter discusses the environmental noise assessment standards of the International Organization for Standardization, ISO. In addition to ISO standards 1) ISO 1996-1 – “Basic quantities and assessment procedure,” and 2) ISO 1996-2 – “Acquisition of data pertinent to land use,” national and local standards are also presented and discussed. This chapter reviews noise map calculations and design, as well as the model for calculating road traffic noise contained in the ISO 9613-2 standard.
Chapter 2 describes mathematical models based on statistical analyses to calculate nighttime and daytime highway traffic noise. Unlike the daytime model, the nighttime model is presented with class intervals.
A methodology for the assessment of environmental noise generated by heavy traffic on an urban stretch of a highway is discussed in Chapter 3. The noise pollution assessment was based on extensive field measurements of equivalent sound pressure levels and the subsequent calculation of noise maps. The noise maps were calculated based on heavy vehicle counts, road conditions, and average speed of vehicle traffic. The noise levels recorded on this road exceed the levels recommended by current legislation and indicate that taking only one control measure does not suffice to counteract noise efficiently. Instead, a plan involving various measures taken jointly is needed to effectively mitigate the problem.
Urban noise has often been cited as an environmental impact that affects society negatively, which is why it has been analyzed with greater care in reports submitted to government environmental agencies. Chapter 4 offers a detailed explanation of how to characterize noise in a community, thus assisting in decision-making for urban planning, environmental control and environmental licensing. To this end, noise characterization is performed quantitatively and qualitatively, the former by means of noise monitoring and modeling, and the latter by means of sound perception interviews, soundwalks and hearing tests.
Chapter 5 describes noise in urban areas surrounding power substations. The noise levels that reach houses and buildings situated around the substations is then quantified based on noise maps.
Urban parks are considered important locales for physical activity. It is therefore essential that park settings be attractive and of good quality, since they can contribute to improve the quality of life of urban populations through the practice of physical exercise. Chapter 6 describes the quality of environmental sound in public parks. Based on environmental noise measurements and noise mapping, an investigation was made to determine if the fitness and leisure equipment (sports courts, equipment for push-ups, sit-ups and leg stretching, walking simulators and playground) inside parks are located in areas exposed to environmental noise from the immediate surroundings (thoroughfares with heavy vehicle traffic). It was found that the LAeq levels in the areas closest to the outer perimeters of the parks are higher than in the more distant areas. Thus, primarily due to the urban shape of the surroundings, environmental noise was found to have a negative effect on urban park environments. This effect could be mitigated by building thoroughfares with heavy traffic further away from parks, considering the urban context of the park, and/or by placing fitness and leisure equipment at a greater distance from the park’s outer perimeters, thereby promoting greater acoustic comfort.
Chapter 7 describes a study of sound pressure levels and frequency spectrum measured in the surroundings of the Polytechnic Center of the Federal University of Paraná (Campus III), located in Curitiba, Brazil. The findings indicate that the measured sound pressure levels exceed not only the limits specified by Brazil’s environmental standards but also those established by the municipality of Curitiba for educational environments. The analysis of the noise frequency spectrum around the Polytechnic Center campus reveals a wide range of frequencies varying from 50 Hz up to, in some cases, 10000 Hz, 12500 Hz, 16000 Hz and 20000 Hz. This finding is one that causes concern, because a combination of high sound levels and high frequencies can interfere in the cognitive process of students and teachers, impairing the teaching and learning process.
An investigation of noise levels on dedicated bus lanes in the integrated bus rapid transit system (BRTS) of the city of Curitiba is described in Chapter 8. Equivalent sound pressure levels (Leq) along the traffic lanes were measured and also predicted through computer simulations based on noise map calculations.
Chapter 9 highlights the concerns about noise levels in the modern world, which have worsened as a result of urbanization and industrialization. These factors have impaired the sound quality in urban areas due to the multiplicity of noise sources. This chapter describes the problem of noise pollution in São Paulo, one of the world’s largest cities. One of the districts in the municipality of São Paulo, comprising an area of approximately 8 km2, was selected for a noise assessment based on noise maps, and an evaluation of the effects of noise on the health of the population based on a household survey about noise-related annoyance and sleep disturbance. An analysis of the noise maps revealed high sound pressure levels caused by urban traffic, ranging, in some cases, from 80 to 85 dB(A). The percentage of people suffering from a high rate of sleep disorders (Ln indicator – % HSD) and people highly annoyed (Lden indicator - %HA) due to noise was considerably greater than that recommended by the World Health Organization. The problem of noise pollution should be considered a priority in environmental planning, in order to improve urban soundscapes and education on environmental health so as to increase people’s well-being and quality of life.
Chapter 10 presents an assessment of noise levels on the Federal University of Paraná Jardim Botânico Campus II, based on sound measurements and calculated noise levels using noise mapping. This campus is surrounded by streets with intense vehicle traffic, which contributes to cause the noise levels to exceed the legal limits established for educational areas.
Buildings with multiple floors are exposed to external noise levels that vary according to the height of each floor above ground. These levels must be known in order to design the proper sound insulation for each floor. Chapter 11 proposes a methodology aided by three-dimensional acoustic mapping to design the sound insulation of building facades. The technique consists basically of three stages: creation of an acoustic map of the region and the buildings of interest, determination of the sound insulation requirements of each floor, and dimensioning of their exterior facade elements. The method is applied to a building of 152 meters with 44 floors, which is taken as an example. The results indicate that the floors of the building are exposed to four different ranges of sound pressure levels, and thus have different sound insulation requirements. Using this method, different types of windows are selected to meet the requirements of each floor, taking into account safety aspects in the dimensioning, without wasting resources.
Chapter 12 describes a study on noise pollution in downtown Campo Grande, the state capital of Mato Grosso do Sul, Brazil, which has a population of approximately 200,000. Two types of noise maps are created, one characterizing the “general situation” to identify the entire range of sound levels, and the other defining the “characteristics of the areas” to illustrate the sound levels that fall below or above the established limits. This dual strategy is very useful for the identification of acoustically polluted streets and areas. Lastly, several noise mitigation measures are suggested, and three new simulated scenarios are presented. However, despite the implementation of low-noise road surfaces for the existing streets and the elimination of heavy vehicles, which reduce the sound levels by 0-5 dB(A) at the facades of buildings along the streets, these noise mitigation measures do not suffice to fully solve the existing problem of noise pollution. It is therefore advisable to implement additional measures to effectively reduce urban noise in cases such as this one.
A rail traffic noise assessment in an urban setting is described in Chapter 13. Measurements were taken of noise levels generated by trains passing through residential neighborhoods with and without blowing their horns. Noise maps were also calculated showing noise pollution generated by the train traffic. The measurements indicated that the noise levels generated by the passage of the train with its horn blowing are extremely high. The noise generated by the train horn affects 750,000 of the 1.8 million inhabitants of the city under study. Therefore, urgent measures are needed to control and reduce these noise levels. In fact, we would do well to keep in mind the words of Fields and Walker (1982): “Noise is rated as the most serious environmental nuisance caused by railways.”
Chapter 14 analyzes the impact of environmental noise generated by a paper mill on its surroundings, based on equivalent noise level measurements and noise mapping. Noise maps are used to simulate noise control solutions at the noise sources. After simulating the effect of the adoption of noise control measures, new simulations of the noise levels reaching the town adjacent to the paper mill confirm the efficacy of the proposed noise control measures. Noise maps are helpful in investment planning because they allow for budgetary control, i.e., prioritization of the most critical actions that will actually be effective in controlling industrial noise that impacts surrounding communities.
Chapter 15 discusses a methodology for determining the contribution of environmental noise to the noise pollution generated by a factory, by comparing experimental measurements of environmental sound pressure levels against noise maps showing the propagation of industrial noise. An auto parts plant was chosen for a case study, and experimental measurements of sound pressure levels were taken at discrete points, called receivers, located along two rings around the plant. The noise measurements taken along the inner ring were entered into a software program in order to iteratively quantify the plant’s most important noise sources. The program then generated noise propagation maps and simulated sound pressure levels at the receiver positions along the outer ring. These simulated sound pressure levels were then compared with the experimental noise measurements taken at the outer ring to ascertain the contribution of environmental noise sources to the noise emissions of the factory. The placement of partial barriers along some critically noisy walls was found to be effective in controlling the nighttime impact noise, preventing noise immission levels exceeding 60 dB(C) from reaching the neighborhoods surrounding the plant.
Any intervention in an urban environment that leads to variations in a determinant parameter or variable of the noise emission process should be assessed predictively and proactively in the medium and long term, in view of its possible effects on the environment where it is implemented. Hence, scientific tools must be developed to measure the impact of noise pollution in urban areas. Chapter 16 presents a prediction matrix for the assessment of traffic-related noise pollution. This matrix, which was created based on noise prediction maps, allows for the qualification and quantification of the global impact of environmental noise resulting from the implementation of a road construction project and its operation.
Chapter 17 describes the reactions to aircraft noise of people living in the proximities of a medium sized airport located in a densely populated urban area, based on a questionnaire distributed to people living or working near this airport to determine how they are affected by aircraft noise and environmental noise in general. The maximum equivalent sound pressure level, LMax, generated during aircraft takeoffs exceeds 100 dB(A). Sound maps of the airport and its surroundings were calculated to evaluate the impact of environmental noise generated by the daily air traffic flow. One of the main complaints of the questionnaire’s respondents was sleep disruption between 6 and 8 am, which is the period corresponding to the highest flow of airplane takeoffs and landings.
In addition to the substantial amount of research that has focused on human well-being, the impact of noise on wildlife has gained considerable scientific attention in recent years. Nevertheless, studies in South American countries are still scanty. To address this lack, chapter 18 of this book analyzes the possible disruption of the acoustic communication in birds caused by urban noise. The chapter begins with an overview of what is known on the subject, followed by acoustical data of both urban noise and birdsong measured in a city in southern Brazilian. The idea is to offer the reader a general introduction to the theme, as well as a preliminary assessment of how problematic these impacts can be nationwide. In addition, given that this research field is still incipient in Brazil, new investigations may lead to very different avenues of interest, of both theoretical and applied focus.
The topics presented and discussed in this book, considering the proper distance and relativity specific to each country, can help to solve and/or shed light on local problems that involve urban and industrial noise pollution.
This book should be of interest for use in theory and practice. We believe that numerous professionals, even those not specialized in noise control, will find it useful. The target audience of this book includes undergraduate and graduate students, as well as professionals working in the areas of environmental management of cities, of factories, in architecture, urban design, in environmental, mechanical and civil engineering, urban planning, health care professionals, etc.
The Editor gratefully acknowledges the German Government, through the German Academic Exchange Service – DAAD (Deutscher Akademischer Austauschdienst) and the Brazilian Government, through the National Council for Scientific and Technological Development – CNPq, for their financial support, which enabled the purchase of the sound level meters and software used in the studies described in this book. Special thanks go to CNPq, whose Grants Nos. 302738/2010-0 and 303786/2014-0 financed the translation of this book from Portuguese to English.
Last but not least, the Editor and all the other authors of this book express their sincere thanks to Ms. Beatrice Allain for her excellent work and dedication in translating all the chapters from Portuguese into English.
Full Professor Dr.-Ing. Paulo Henrique Trombetta Zannin
Curitiba
February 21, 2016
This study investigates the level of noise to which bus fare collectors in Curitiba's express bus stations are exposed during their workday. The object of analysis are the tube bus stations located on Padre Anchieta and Sete de Setembro avenues in the south sector of the city of Curitiba, Brazil, which is characterized by its high housing density and high average per capita income. The high densities and economic profile produce a greater flow of light vehicles which contributes to the increase in noise levels. At the 9 bus stations, where equivalent noise levels (Leq) were measured, at 10-minute intervals, the workplace noise levels, were found to be in compliance with the limits established by the Brazilian national standard NR-15, which address occupational noise exposure, since the 9 samples studied here, showed equivalent noise levels below 80 dB(A), sound level from which there is an indication of auditory risk. However, the environments of all the samples showed measured equivalent sound levels exceeding Leq = 65 dB(A), thus characterizing them as uncomfortable according to Brazil's regulatory standard NR-17, which establishes ergonomic standards for the workplace.
In order to control growing noise pollution in urban indoor substations efficiently, calculation of the sound field in chambers and residential areas is done. With the software ANSYS 11.0 SP1, Nanjing Daxinggong 220 kV substation and Fucheng 220 kV substation are taken as examples to simulate and analyze the sound field in the main transformer chamber as well as the reactor chamber. Meanwhile, LMS SYSNOISE is utilized to simulate and calculate the sound field of residential areas, 45 m away from the main transformer chamber. According to simulation results, the sound pressure level in the main transformer chamber reaches a maximum of 90.6 dB at the frequency of 63 Hz, while the sound pressure level in the reactor chamber reaches a maximum of 93.0 dB at 125 Hz. The A-weighted equivalent continuous sound pressure level in residential areas is 47.51 dB, exceeding our national emission standard at night. The calculation results are in good agreement with the experimental data. The model can be modified to simulate and predict the sound field in substations of the same kind so as to put forward an optimum proposal for noise treatment based on techniques of noise insulation, noise elimination, noise absorption as well as vibration isolation.
This paper evaluates acoustic quality of university classrooms in terms of acoustical parameters [external and internal equivalent sound pressure level, reverberation time(RT) and sound insulation of façades]. Field measurements of equivalent sound pressure level were taken during daytime using sound pressure level meter according to NBR 10152 standard. Sound signatures were analyzed by real-time sound analyzer. Only one classroom of BG building exhibited internal equivalent sound pressure level exceeding permissible value of 50 dB(A). RT values, measured in PC Building, were in 6 classrooms in accordance with recommended values from international standards. On the other hand, in BG building, RT measured in all classrooms exceeded established limits. Only completely occupied classrooms in BG building exhibited better acoustic quality in terms of RT as compared to partially occupied and empty classrooms. Apparent weighted sound reduction indices of façades of both buildings showed values far below those recommended by international standard as DIN 4109.
This study investigates extremely low noise level for three-phase three-limb transformer core, which the magnetostriction variation effect of external stress on three-phase power transformer core, with capacity of 450kVA, which induced different noise and vibration variation, is performed. It has constructed special two types of square-cored and D-yoked core power transformers and to measure magnetic properties by different stress were analyzed. The sample of silicon sheet material of 27PH100 for power transformer core has been used. The magnetostriction and B-H curve noise level and core vibration, has been measured by different external stress on transformer core. In order to compare the different results for measurement and simulation, this paper also built a simulated model for three phase power transformer. For noise level and vibration results, the external stress has performed when the core was operated at 50Hz and 60Hz. According to the measured results, it is indicated that the better stress will also be induced appropriates magnetic property which including magnetic loss, noise level and vibration.
This paper evaluates acoustic quality of university classrooms in terms of acoustical parameters [external and internal equivalent sound pressure level, reverberation time(RT) and sound insulation of façades]. Field measurements of equivalent sound pressure level were taken during daytime using sound pressure level meter according to NBR 10152 standard. Sound signatures were analyzed by real-time sound analyzer. Only one classroom of BG building exhibited internal equivalent sound pressure level exceeding permissible value of 50 dB(A). RT values, measured in PC Building, were in 6 classrooms in accordance with recom-mended values from international standards. On the other hand, in BG building, RT measured in all classrooms exceeded estab-lished limits. Only completely occupied classrooms in BG building exhibited better acoustic quality in terms of RT as compared to partially occupied and empty classrooms. Apparent weighted sound reduction indices of façades of both buildings showed values far below those recommended by international standard as DIN 4109.
The relationship between noise and air pollution was investigated in eight different districts across Seoul, Korea, between September and November 2010. The noise levels in each district were measured at both roadside and non-roadside locations. It was found that the maximum levels of noise were generally at frequencies of around 1000 Hz. The equivalent noise levels (L(eq)), over all districts, averaged 61.4 ± 7.36 dB which is slightly lower than the noise guidelines set by the World Health Organization (WHO) of 70 dB for industrial, commercial, traffic, and outdoor areas. Comparison of L(eq) levels in each district consistently indicates that noise levels are higher at roadside sites than non-roadside sites. In addition the relative dominance of noise during daytime as compared to nighttime was also apparent. Moreover, the results of an analysis relating sound levels with air pollutant levels indicate strongly that the correlation between these two parameters is the strongest at roadside sites (relative to non-roadside sites) and during nighttime (relative to daytime). The results of our data analysis point to a positive, but complex, correlation between noise levels and air pollution.
The present study provides an evaluation of noise pollution in six Urban Parks located in the city of Curitiba, Brazil. Equivalent noise levels (L
eq) were measured in 303 points (each point measured during 3 min) spread throughout the Parks. Measured values were confronted with local legislation (Law 10625) allowed limits, and the Parks were thus classified as “acoustically polluted or unpolluted”. Measured values were also evaluated according to international legislation: Decree no. 12 of the City Council of Rome, DIN 18005 for German cities, the World Health Organization, and the United States Environmental Protection Agency. Urban parks in the downtown area of Curitiba, surrounded by roads of heavy traffic and in the midst of intense commercial activities, do not satisfy any of the standards used. The most noise-polluted parks in Curitiba were the Public Walk Park and the Botanical Garden Park, with measured L
eq of 64.8 dB(A) and 67 dB(A).
Descreve-se a reação da população de Curitiba, PR -- cidade com aproximadamente 1,6 milhões de habitantes --, ao ruído ambiental . Os dados foram coletados por meio de questionários distribuídos aleatoriamente a moradores da cidade. Dos 1.000 questionários distribuídos, 860 (86%) foram avaliados. As principais fontes de ruído causadoras de incômodo identificadas foram o tráfego de veículos (73%) e os vizinhos (38%), sendo que estes foram classificados como a principal fonte de desconforto. Todos os respondentes apontaram pelo menos um dos seguintes itens como geradores de ruído: vizinhos, animais, sirenes, construção civil, templos religiosos, casas noturnas, brinquedos e aparelhos domésticos. As principais reações ao ruído foram: irritabilidade (58%), baixa concentração (42%), insônia (20%) e dores de cabeça (20%).
This paper presents a study on noise pollution in residential areas of a large Brazilian city, Curitiba. The equivalent sound level values - L-eq - were measured and tabulated for 350 locations spread over residential areas. The results showed that 80.6% of the measured points exceeded 65 dB(A). Only 9.4% of the measured points satisfy the 55 dB(A) limit for residential areas during daytime (7:00am - 7:00pm), according to the environmental legislation in effect in the city.
A field study has been carried out in urban Nigeria the results of which show that most urban dwellers consider noise an environmental nuisance, with 65% of all respondents in eight cities feeling highly or moderately disturbed by it. This feeling appeared strongest in the more densely populated areas such as Lagos and Onitsha. The greatest source of noise nuisance was found to be electrical audio equipment (radios, stereo record players, public address systems and so on). Noise interfered with people's sleep and other activities during rest periods, especially at night, and most people (84%) wanted the noise nuisance legally controlled. Many aspects of the results of the survey are in line with those of similar surveys undertaken in other parts of the world. In comparing such results with ours there was not sufficient data to reach a definite conclusion on whether or not differences with respect to the perception of noise do exist between the major races on account of physiological and cultural differences.
The extent of annoyance caused by road traffic noise was investigated in 15 areas with a varying number of vehicles and different distances between the traffic and houses. The goal was to compare two principles for expressing noise exposure. One was based on the conventional energy equivalent value in terms of a 24-hourLAeqvalue. The other was based on the number of events and noise level as two independent variables. A postal questionnaire study was performed in the different areas, and noise exposure measurements were made at a representative site in each area. The individual noise exposure was calculated on the basis of the distance of the respondent from the road and the floor level. The results showed that the number of noise events did not influence the extent of annoyance. There was a strong relationship between theLAeqand the extent of annoyance as well as between the maximum noise level and the extent of annoyance. These data suggest that actions to control the disturbing effects of road traffic noise should focus on noisy vehicles and that limiting the number of vehicles would not have an effect on the extent of annoyance.
Path analysis was applied to data collected in a social survey on the community response to traffic noise along a trunk road in Tokyo. The data were collected from more than 390 female residents by means of a questionnaire. A path model was developed for the causal relation of the noise annoyance, dissatisfaction with living environment, and the wish of the respondents to move to the antecedent variables, including noise levels, personal factors, and noise effects. The strongest effect on annoyance was for the noise level, followed by interferences with daily activities. The model explains 43% of the variation in annoyance. The dissatisfaction with the living environment and wish of respondents to move depended strongly on noise annoyance, but other factors should also be considered, as only 33% and 19% of their variation, respectively, could be explained by the model.
In an effort to determine the contribution of night-time road traffic noise to insomnia in the general population, 3600 adult Japanese women living in urban residential areas were surveyed. Living near a road with a heavy traffic volume is one of the risk factors for insomnia. The risk for insomnia in the zones 0–20 m from the main roads increased linearly with the night-time traffic volume. This suggests that road traffic noise raises the sound level in bedrooms in such zones, and consequently the prevalence rate of insomnia among the residents, and that noise-induced insomnia is an important public health problem, at least in highly urbanized areas.
This paper presents a study on noise pollution in residential areas of a large Brazilian city, Curitiba. The equivalent sound level values - Leq - were measured and tabulated for 350 locations spread over residential areas. The results showed that 80.6% of the measured points exceeded 65 dB(A). Only 9.4% of the measured points satisfy the 55 dB(A) limit for residential areas during daytime (7:00am – 7:00pm), according to the environmental legislation in effect in the city.
This paper presents the results obtained in a study on environmental noise pollution in the city of Curitiba, Brazil. The equivalent sound level values—LAeq, 2hr—were measured and tabulated for 1000 locations spread over the urban zones of the city of Curitiba. It has been found out that 93.3% out of the locations display during the day equivalent sound levels over 65 dB(A), and 40.3% out of the total number of locations measured display during the day extremely high values of equivalent sound levels: over 75 dB(A).
The study describes people's reaction to environmental noise in Curitiba, a city of approximately 1.6 million inhabitants in Brazil. Data was collected using questionnaires randomly delivered to the city's residents. Out of 1,000 questionnaires, 860 (86%) were returned and assessed. The main noise sources found as disturbing were motor vehicle traffic (73%) and neighbors (38%), which were rated as producing the most disturbing noise. All respondents pointed out at least one of the following as noise sources: neighbors, animals, sirens, civil construction, religious worship temples, nightclubs, toys, and domestic electric appliances. The main reactions to noise exposure were: irritability (58%), difficulty to concentrate (42%), sleeping disorders (20%), and headaches (20%).
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Mapeamento de Emissão Acústica em Subestações Elétricas
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Rodrigues, VF. Mapeamento de Emissão Acú stica em Subestaçõ es Elétricas. Belo Horizonte,
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