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This study was supported within the scope of The Scientific and Research Council of Turkey-1001 Research Grant Scheme under Project No. (114K738) and Project Title of “Noise Pollution in School: Causes, Effects, and its Control”. The authors would like to thank Prof. Dr. Ali Yurdun Orbak for his valuable contribution during the measurements in the school without acoustic treatment. There is limited data for assessing speech intelligibility in real classrooms with realistic occupied noise levels and teacher's and students’ speech levels for different teaching activities in Turkish secondary school classrooms. This study investigates the effect of reverberation time (RT), occupied noise levels and signal-to-noise ratio (SNR) on speech transmission index (STI) in real classrooms for instruction and group work. Noise levels were measured and STI values were calculated in two secondary school classrooms with RT of 0.88 s and 2.73 s. During instruction situation, calculated mean STI values were 0.63 (classroom with acoustic treatment) and 0.29 (classroom without acoustic treatment) for normal voice effort and 0.65 (classroom with acoustic treatment) and 0.39 (classroom without acoustic treatment) for raised voice effort. During group work, STI values ranged from 0.50 to 0.74 in classroom with acoustic treatment and from 0.01 to 0.34 in classroom without any acoustic treatment. SNR of 15 dBA is only approached in classroom with acoustic treatment during instruction situation. The effect of increasing SNR on STI is prominent in the classroom without acoustic treatment which already has low SNR values. The present results show that the classroom with acoustic treatment will have good speech intelligibility for instruction with normal vocal effort and for group work with raised vocal effort at 3 m distance. However, the classroom with no acoustic treatment will have STI values in the range of bad and poor intelligibility. The present results confirm the impact of SNR and RT on speech intelligibility and shows that RT value of minimum 0.8 s is optimal to have good speech intelligibility in a secondary school classroom of approximately 250 m3 with a capacity of 18 students. Scientific and Research Council Publisher's Version Q1 WOS:000976020200001

[ES] Este trabajo de fin de grado pretende comparar dos destinos turísticos de playa en las ciudades de Rethymno (Grecia) y la Playa de Gandía (España). Ambos son destinos turísticos muy conocidos en sus respectivos países. Para ello, se realizarán mediciones en temporada turística (por cada una de las franjas horarias establecidas por la europea vigente) en cada uno de los 6 puntos distribuidos en las zonas de interés, y se estudiará el nivel de ruido registrado en ellas, tras realizar los correspondientes promediados y tener en cuenta las fuentes de ruido existentes en cada lugar para el diseño de mapas acústicos con los que poder comparar ambos destinos. El estudio permitirá determinar si existen niveles y comportamientos similares o, por el contrario, hay diferencias notables en función del destino elegido., [EN] This final degree project aims to compare two beach resorts in the cities of Rethymno (Greece) and Playa de Gandía (Spain). Both are well-known tourist destinations in their respective countries. To this end, measurements will be taken during the tourist season (for each of the time slots established by the current European law) at each of the 6 points distributed in the areas of interest, and the noise levels recorded in them will be studied, after carrying out the corresponding averages and considering the existing noise sources in each place for the design of acoustic maps with which to compare the two destinations. The study will make it possible to determine whether there are similar levels and behaviours or, on the contrary, there are notable differences depending on the destination chosen.

The objective of the research was to quantify the levels of noise and carbon dioxide (CO2) to which people are exposed to punctually or more continuously. Data collection was performed at 5 points in the city of Campina Grande, namely: the passenger integration terminal and the bus station, the Federal University of Campina Grande, the children's park and Maciel Pinheiro Street located downtown. Data collection took place from 10 am to 11:30 am, with one day in each location. The methodology adopted to evaluate the noise levels was based on NBR 10.151/2000, and the results were compared to the environmental legislation and the State Decree 15.357/1993, which set the conditions of acceptability. As for the concentration of CO2, the results obtained were compared to the values set in NR-15, Annex 11. The results showed that the Passenger Integration Terminal has more critical values regarding the noise issue, obtaining an average level of 75.17 dB, justified by the higher vehicle flow among the analyzed points. The Federal University of Campina Grande presented a more comfortable situation regarding sound pressure, being, therefore, in accordance with the current legislation. The CO2 concentrations did not present values harmful to human health, as well as to the environment in all sites analyzed. As for noise pollution, it is recommended that urban planning be carried out using shrub species that will act as natural barriers, together with monitoring by the competent bodies to curb abusive noise practices by some local businesses. El objetivo de la investigación era cuantificar los niveles de ruido y de dióxido de carbono (CO2) a los que están expuestas las personas de forma puntual o más continua. La recogida de datos se realizó en 5 puntos de la ciudad de Campina Grande, a saber: la terminal de integración de pasajeros y la estación de autobuses, la Universidad Federal de Campina Grande, el parque infantil y la calle Maciel Pinheiro, situada en el centro de la ciudad. La recogida de datos se llevó a cabo de 10 a 11:30 horas, y se realizó un día en cada lugar. La metodología adoptada para evaluar los niveles de ruido se basó en la NBR 10.151/2000, y los resultados se compararon con la legislación medioambiental con el Decreto Estatal 15.357/1993, que establece las condiciones de aceptabilidad. En cuanto a la concentración de CO2, los resultados obtenidos se compararon con los valores establecidos en la NR-15, Anexo 11. Los resultados mostraron que la Terminal de Integración de Pasajeros tiene valores más críticos en cuanto al tema del ruido, obteniendo un nivel medio de 75,17 dB, justificado por el mayor flujo de vehículos entre los puntos analizados. La Universidad Federal de Campina Grande presentó una situación más cómoda en cuanto a la presión acústica, estando, por tanto, de acuerdo con la legislación vigente. Las concentraciones de CO2 no presentaban valores perjudiciales para la salud humana ni para el medio ambiente en todos los lugares analizados. En cuanto a la contaminación acústica, se recomienda la planificación urbanística utilizando especies arbustivas que funcionen como barreras naturales, junto con la supervisión por parte de los organismos competentes para frenar las prácticas acústicas abusivas de algunos comerciantes locales. O objetivo da pesquisa foi quantificar os níveis de ruído e dióxido de carbono (CO2) ao qual as pessoas estão expostas de modo pontual ou mais contínuo. A coleta de dados foi realizada em 5 pontos da cidade de Campina Grande, a saber: o terminal de integração de passageiros e o rodoviário, a Universidade Federal de Campina Grande, o parque da criança e a Rua Maciel Pinheiro localizada no centro da cidade. A coleta de dados ocorreu das 10 às 11h30min, sendo realizado um dia em cada local. A metodologia adotada para avaliar os níveis de ruído foi baseada na NBR 10.151/2000, e os resultados foram comparados a legislação do meio ambiente com o Decreto Estadual 15.357/1993, que fixam as condições de aceitabilidade. Quanto a concentração de CO2, os resultados obtidos foram comparados aos valores fixados na NR-15, anexo 11. Os resultados mostraram que o Terminal de Integração de Passageiros possui valores mais críticos quanto questão sonora, obtendo nível médio de 75,17 dB, justificado pelo maior fluxo de veículos dentre os pontos analisados. A Universidade Federal de Campina Grande apresentou situação mais confortável quanto à pressão acústica, estando, assim, em consonância com a legislação vigente. As concentrações de CO2 não apresentaram valores prejudiciais à saúde humana, bem como, ao meio ambiente em todos os locais analisados. Quanto a poluição sonora orienta-se para o planejamento urbano utilizando espécies arbustivas que funcionará como barreiras naturais, aliado a fiscalização pelos órgãos competentes para coibir práticas sonoras abusivas por parte de alguns comerciantes locais.

International audience; When it comes to the electromagnetic interference (EMI) immunity of a Battery Management System Integrated Circuit (BMS IC), Printed Circuit Board (PCB) traces, external components and BMS impedance have a major impact. In a number of cases, electromagnetic compatibility (EMC) issues are reported at the last testing phase which can lead to design changes thus increasing cost and time to market. In this context, this work gives an insight on what some design choices on the external components, PCB traces and hot-plug (HP) protection architecture can lead to in terms of the noise coupled to the BMS IC. Moreover, an analytical model based on ladder network theory is used to predict the main noise coupling frequencies under some low-cost design choices. This model is then used in the comparison of two HP protection architectures in terms of the noise coupled onto the BMS IC.

International audience; Many works [2][3] make use of high frequency battery models and Printed Circuit Board (PCB) models for EMC emission characterization. This work proposes those models in addition to a Battery Management System (BMS) impedance to show the effect on the noise received by the BMS under Direct Power Injection (DPI) simulations with different external components configurations. Furthermore, in order to ease some of the first design stages of the BMS and its external components, a straightforward analytical model to estimate the noise levels and its maximum coupling frequencies during DPI simulations is also elaborated and validated by simulations.

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2022-12-19T11:45:29Z No. of bitstreams: 1 2020 - Fabiano Battemarco da Silva Martins.pdf: 1782710 bytes, checksum: f2e9ce3261d4d818cd4ddc17721c279d (MD5) Made available in DSpace on 2022-12-19T11:45:29Z (GMT). No. of bitstreams: 1 2020 - Fabiano Battemarco da Silva Martins.pdf: 1782710 bytes, checksum: f2e9ce3261d4d818cd4ddc17721c279d (MD5) Previous issue date: 2022-02-07 CAPES - Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior Noise is one of the physical agents that offer occupational hazards in which workers, when overexposed to them, may be subject to a series of injuries. Agricultural machines are an important source of noise in the agricultural environment. Thus, the objective of the present work is to use geostatistics and, also, statistical process control (CEP) to map the spatial distribution of noise emitted by agricultural tractors with and without the activation of agricultural implements in order to evaluate the areas of healthiness for all workers involved in mechanized operation, in the light of Regulatory Standard 15 (NR 15). The experiment was developed at the Federal Rural University of Rio de Janeiro (UFRRJ), Serop?dica-RJ and at the Federal University of Lavras (UFLA). The tractors were tested with and without driving agricultural implements. The implements to be driven by the tractors were, the brushcutter, the rotary hoe and the spreader of fertilizers. The digital decibel meter was used to collect noise levels at points distributed in a regular sampling grid of 1.0 x 1.0 m at UFRRJ and 2.0 x 2.0 m at UFLA around these machines. The spatial dependence of the noise was analyzed by adjusting the wave semivariogram and interpolation by ordinary kriging. And also, through individual letters in the statistical process control (CEP). Therefore, it was possible to characterize the structure and magnitude of the spatial dependence on the noise levels emitted by the tractor, as well as to map its spatial distribution in order to identify healthy areas for workers O ru?do ? um dos agentes f?sicos que oferecem riscos ocupacionais no qual os trabalhadores quando expostos demasiadamente a estes podem estar sujeitos ? uma s?rie de les?es. As m?quinas agr?colas s?o uma importante fonte emissora de ru?dos no meio agr?cola. Dessa maneira, objetiva-se no presente trabalho, utilizar a geoestat?stica e, tamb?m, o controle estat?stico de processos (CEP) para mapear a distribui??o espacial do ru?do emitido por tratores agr?colas com e sem acionamento de implementos agr?colas de forma a avaliar as zonas de salubridade para todos os trabalhadores envolvidos na opera??o mecanizada, a luz da Norma Regulamentadora 15 (NR 15). O experimento foi desenvolvido na Universidade Federal Rural do Rio de Janeiro (UFRRJ), Serop?dica-RJ e na Universidade Federal de Lavras (UFLA). Os tratores foram testados com e sem acionamento de implementos agr?colas. Os implementos ? serem acionados pelos tratores foram, ? ro?adora, a enxada rotativa e a esparramadora de adubos. O decibel?metro digital foi utilizado para a coleta dos n?veis de ru?do em pontos distribu?dos numa malha amostral regular de 1,0 x 1,0 m na UFRRJ e 2,0 x 2,0 m na UFLA ao redor destas m?quinas. A depend?ncia espacial do ru?do foi analisada por meio de ajuste de semivariograma do tipo Wave e interpola??o por krigagem ordin?ria. E, tamb?m, atrav?s de cartas individuais no controle estat?stico de processos (CEP). Assim sendo, foi poss?vel caracterizar a estrutura e a magnitude da depend?ncia espacial dos n?veis de ru?do emitido pelo trator, bem como realizar o mapeamento de sua distribui??o espacial de forma a identificar zonas salubres aos trabalhadores

Noise pollution has been rising as a critical issue in recent days particularly for the people living in urban areas. This study has been conducted to find out the effects of traffic induced noise on nearby residential building through 3D noise mapping with and without noise Barriers. Monitoring has been carried out at various densely populated preselected locations of Delhi, India. Thereafter, 3D noise mapping has been done using hourly average noise levels for the locations exposed with maximum noise. The developed 3D noise map shows the variation of noise level along X, Y and Z direction for all selected locations before and after installation of noise barriers. Moreover, the result also shows that exact assessment of noise impact is possible through 3D noise mapping, when a multistory building close to the source of noise is taken into consideration. This paper also elaborates the adequate height, distance and NRC value of noise barrier to reduce the effect of road traffic noise on nearby high rise building. Reduction pattern of noise level can easily be visualized and evaluated by using these maps. This type of study could support decision makers during adaptation of suitable remedial measures.

This paper presents an inside-cabin acoustic evaluation of the IAR PUMA 330 helicopter, manufactured by IAR S.A. Brasov. In this study, based on the acoustic assessment inside the helicopter, areas with high noise levels are identified. In this regard, several tests were carried out in accordance with the ISO 5129 standard. In the first stage of the assessment, a measurement campaign was performed to identify the acoustic leaks from the outside noise sources propagating inside the cabin (in the door area) and the acoustic attenuation of the helicopter structure. These tests were performed on the factory runway, with the helicopter in parked position (ground tests). During the ground tests, the helicopter engines were turned off. The tests consisted of placing two loudspeakers directed towards the helicopter door and generating pink noise. Inside the helicopter, the entire door frame opening was scanned with an intensity probe to identify acoustic leaks areas. The second assessment stage was to determine the areas of the cabin with the highest levels of noise. Within the measurement campaign, 16 microphones were placed inside the cabin, at the level of the passengers’ heads, arranged in seven zones. The tests were carried out with the helicopter engines started, staying at fixed point above the ground (hovering), and then a flight test, in which all the maneuvers necessary for the use of the helicopter were performed (in-flight tests). Based on the measurement results, it was possible to highlight the noise spectral components in each of the seven areas. The noise assessment revealed high noise levels inside the cabin, having as main noise sources the transmission gear and the door area, leading to the need for reducing the noise exposure for passengers and crew, thus the need to reduce noise levels inside the helicopter.

International audience; Visual observations of the marine biodiversity can be difficult in specific areas for different reasons, including weather conditions or a lack of observers. In such conditions, passive acoustics represents a potential alternative approach. The objective of this work is to demonstrate how information about marine biodiversity can be obtained via detailed analysis of the underwater acoustic environment. This paper presents the first analysis of the Saint-Pierre-and-Miquelon (SPM) archipelago underwater acoustic environment. In order to have a better knowledge about the marine biodiversity of SPM, acoustic recordings were sampled at different time periods to highlight seasonal variations over several years. To extract information from these acoustic recordings, standard soundscape and ecoacoustic analysis workflow was used to compute acoustic metrics such as power spectral density, third-octave levels, acoustic complexity index, and sound pressure levels. The SPM marine acoustic environment can be divided into three main sound source classes: biophony, anthrophony, and geophony. Several cetacean species were encountered in the audio recordings including sperm whales (which were detected by visual observations and strandings of 3 males in 2014), humpback, and blue whales.

Problem background: This thesis in building technology at Mälardalen University examines the noise level of the constructions on Öster Mälarstrand. The area Öster Mälarstrand is in the eastern part of Västerås next to the water area Mälaren. This district began to build in the end of the 20th century, and the area went from an industrial field to become as described, one of the best places in Västerås to live at. The district is now an area with a large extent of residentials and other necessities such as banking, gym, cafes, restaurants, shops and a large marina. Öster Mälarstrand is still under constant construction of new buildings. The purpose of the survey is to investigate the noise level on Öster Mälarstrand, and if the construction sites are customised to the guidelines that exist regarding noise and noise levels outside in a residential area. The work is summarized and ends by giving examples of measures to reduce noise and noise levels in the area. The method is based on own noise measurements, calculations and interviews. The noise measurements carried out at three specific locations on Öster Mälarstrand during four working days when constructions were underway. Interviews have also been conducted with 50 people who live in the area. The calculations of the noise measurments showed several varying values, but one thing that is clear is that the noise calculations that was executed, exceeds the guideline values set for noise-levels in Öster Mälarstrand. The interviews that were conducted presents that a majority of the interviewees thought that the noise level of the constructions on Öster Mälarstrand was disturbing, especially now during the pandemic of Covid-19, when several people started working from home. The conclusion in this thesis is that noise levels exceeds the guideline values ​​that exist according to the Swedish Environmental Protection Agency. The interviews in the area show that the majority of the participants experience the noise from the construction site as a disturbance.

Continuous time series data from geomagnetic observatories are increasingly contaminated by anthropogenic noise related to developing socio-economic activities. More and more sophisticated techniques of data processing are used to eliminate this noise; nonetheless, some of it cannot be removed. The main sources of noise in the Hyderabad (HYB) data are vehicular traffic, power lines and a power station, 500 m to 1 km away. During the nationwide COVID-19 pandemic lockdown from 24 March to 17 May 2020, both road and metro rail traffic came to a complete halt. The data from this time interval give us an opportunity to evaluate the effects of the absence of traffic-generated noise sources. We found noticeable differences in the noise levels present in vector and scalar variation data, due to the vehicular noise observed before and during the lockdown periods. Noise spectrum estimates quantify the reduction in the noise levels during this period. We also noticed decreased scatter in absolute values of the H (horizontal), D (declination), Z (vertical) and I (inclination) components of the geomagnetic field during lockdown. The details of increased data quality in the absence of traffic-generated noise sources are discussed.

INTRODUCTION: Young people in classrooms are generally listening to speech in an acoustically complex environment composed of long reverberation times and multiple competing voices generated by the room occupants. The challenges of listening to conversation when there are several competing voices is known as the ‘cocktail party’ or ‘multi-talker listening’ effect. Many of the cues that help to filter speech in noise are sometimes inaccessible to young people due to an auditory system that is going through a process of maturation; young people have limited life experience and an underdeveloped knowledge of linguistic rules. Education systems throughout the UK and beyond have gone through a period of reform, with the traditional didactic teaching methods supplemented by more interactive and student-focused learning which are commonly associated with higher noise levels. Several studies have shown that noise levels have a detrimental effect on learning and cognitive function. At the same time, concerns over the general attainment levels in schools and the gap between learners from the most and least deprived areas have come to the forefront of government policy. AIMS: The primary purpose of this research was to evaluate the effects of dynamic soundfield technology on educational attainment with young primary three learners and to determine if its efficacy is moderated by the speech weighted C50 properties of the classrooms. Dynamic soundfield is a technology that monitors the level of background noise in a classroom and adapts the level of gain provided to the teachers’ voice to enhance speech intelligibility in noise. Another primary aim was to explore and evaluate the effects of dynamic soundfield on learners from Scottish Index of Multiple Deprivation (SIMD) 1 and 5 to discover if it contributed to closing the attainment gap between learners from the most and least deprived areas of Scotland. One of the secondary aims of this study was to measure the acoustic properties of the occupied and unoccupied research classrooms and to establish quantitative data on the overall use of the dynamic soundfield systems in each intervention classroom. In addition, the young learners’ and teachers’ experience of noise when exposed to the intervention was compared to the control. The findings from the research are discussed with reference to the literature and in relation to implications for practice. METHODS: This research was a longitudinal repeat measure study design. The 495 primary three learners from 13 schools were allocated to control and intervention classrooms through concealed randomisation. Overall, there were 25 research classrooms, 13 intervention classrooms were fitted with dynamic soundfield (278 learners) and 12 acted as a control (217 learners). All the participants completed the Achievement for Excellence (Interactive Computerised Assessment System) (AfE (InCAS)) suite of adaptive assessments at the start and end of the study. These were administered and marked by the CEM at the University of Durham who were blind to the intervention. RESULTS: Comparisons of the pre-test and post-test Developed Ability and Mental Arithmetic module scores revealed that dynamic soundfield systems were primarily effective in classrooms with good C50 values. In the data handling subtest, the dynamic soundfield intervention produced significant improvements in classrooms with excellent acoustics for speech. In reading, the intervention classrooms categorised as fair and good for speech clarity demonstrated significantly higher learner scores in word recognition, comprehension and reading compared to the control. Only the good C50 intervention classrooms demonstrated a significant improvement in word decoding. Results from a series of two-way mixed ANOVAs showed that learners from the most deprived quintile exposed to dynamic soundfield in classrooms with good C50 values gained a significant benefit in the Developed Ability module and subtests. Learners from the least deprived quintile, in classrooms with excellent C50 values, showed a statistically significant improvement in the General Mathematics subtests of Data Handling and Measure, Shape and Space. Learners from both SIMD 1 and 5 quintiles demonstrated a significant benefit in the Reading module and Word Recognition subtests. Only SIMD 1 learners showed a significant advantage of dynamic soundfield in the word decoding subtest, which was primarily effective in good C50 classrooms. In the Non-Verbal Ability and Word Recognition subtests, there was a significant reduction in the gap between SIMD 1 learners in the intervention classroom and SIMD 5 learners in the control. The views and experiences of learners towards classroom noise and the use of dynamic soundfield were explored quantitively: noise questionnaires were completed by all participants. Logistic regression model analysis revealed that learners exposed to dynamic soundfield could hear the class teacher more easily compared to the control. Overall, the results indicate that dynamic soundfield may be regarded as a cost-effective intervention strategy that could contribute to raising attainment and reducing inequality in Scottish education.

The growing demand for renewable energy supply stimulates a drastic increase in the deployment rate of offshore wind energy. Offshore wind power generators are usually supported by large foundation piles that are driven into the seabed with hydraulic impact hammers or vibratory devices. The pile installation process, which is key to the construction of every new wind farm, is hindered by a serious by-product: the underwater noise pollution. This paper presents a comprehensive review of the state-of-the-art computational methods to predict the underwater noise emission by the installation of foundation piles offshore including the available noise mitigation strategies. Future challenges in the field are identified under the prism of the ever-increasing size of wind turbines and the emerging pile driving technologies.

The growing demand for renewable energy supply stimulates a drastic increase in the deployment rate of offshore wind energy. Offshore wind power generators are usually supported by large foundation piles that are driven into the seabed with hydraulic impact hammers or vibratory devices. The pile installation process, which is key to the construction of every new wind farm, is hindered by a serious by-product: the underwater noise pollution. This paper presents a comprehensive review of the state-of-the-art computational methods to predict the underwater noise emission by the installation of foundation piles offshore including the available noise mitigation strategies. Future challenges in the field are identified under the prism of the ever-increasing size of wind turbines and the emerging pile driving technologies.

Highlights • Full-year monitoring of noise level in central Stockholm, including CoViD-19 period. • Impact of the virus spread and Swedish mitigation strategy on human activity. • Urban noise level reduced up to 4 dB(A) following the national recommendations. • Noise levels in the range of the two major Swedish Public holidays for over a month. • Contrary to discussions in media on the Swedish strategy, strong impact measured., Sweden stands out among the other European countries by the degree of restrictive measures taken towards handling the 2019 coronavirus outbreak, associated with the CoViD-19 pandemic. While several governments have imposed a nationwide total or partial lockdown in order to slow down the spread of the virus, the Swedish government has opted for a recommendation-based approach together with a few imposed restrictions. In the present contribution, the impact of this strategy will be observed through the monitored variation of the city noise levels during the associated period. The data used are recorded during a campaign of over a full year of noise level measurements at a building façade situated in a busy urban intersection in central Stockholm, Sweden. The noise level reductions, observed during the period of restrictions, are shown to be comparable to those found for the two most popular public holidays in Sweden with a peak reduction occurring during the first half of April 2020. Contrary to what has been recently discussed in public media, the spread of the virus, the recommendations, and the restrictions imposed during the ongoing pandemic clearly have had a significant effect on the transport and other human-related activities in Stockholm. In this unique investigation, the use of distributed acoustic sensors has thus shown to be a viable solution not only to enforce regulations but also to monitor the effectiveness of their implementation.

Bakgrund: Tidigare forskning indikerar att höga ljud i öppna kontorslandskap har negativ inverkan på kontorsanställdas prestation och välmående på arbetet. Trots att flertalet studier har gjorts kring olika kontorsmiljöer finns inte mycket forskning om hur ljud i öppna kontorslandskap påverkar behovet av återhämtning efter arbetstid. Syfte: Syftet med studien var att undersöka i vilken utsträckning upplevelsen av höga ljudnivåer och störande ljud på arbetsplatsen har samband med behovet av återhämtning efter arbetstid, bland anställda som arbetar i öppna kontorslandskap. Metod: Metoden bestod av en kvantitativ enkätstudie av tvärsnittsdesign. Behovet av återhämtning mättes utifrån en kortversion av Need for Recovery (NFR) Scale. Ljudnivåer och ljudstörningar mättes utifrån formuläret Ljudstörningar och höga ljudnivåer i arbetsmiljön. Enkäten skickades ut till kontorsanställda på 16 olika arbetsplatser runtom i Sverige, varav sammanlagt 61 respondenter medverkade i studien. Resultat: En hierarkisk multipel regressionsanalys visade ett positivt samband mellan höga ljudnivåer, ljudstörningar och återhämtningsbehov. Ett signifikant samband (p < .05) kunde konstateras mellan ljudstörningar och återhämtning som var oberoende av ljudnivåer. Däremot påvisades inget signifikant samband mellan ljudnivåer och återhämtningsbehov oberoende av ljudstörningar. Slutsats: Resultatet indikerar att störande ljud i öppna kontorslandskap har betydande påverkan på behovet av återhämtning efter arbetstid. Även om inget signifikant samband mellan prediktorvariablerna och utfallsvariabeln kunde påvisas kan ljudnivåer ändå vara betydande för upplevelsen av störande ljud och behovet av återhämtning. För att kunna dra kausala slutsatser är fortsatt forskning genom prospektiva studier nödvändigt. Background: Research indicates that open plan offices are accompanied by high noise levels which have a negative impact on performance and wellbeing at work. However, little is known about how noise levels and noise annoyance associate with need for recovery (NFR) among employees in open-plan offices. Objective: The purpose of this study was to investigate whether there is an association between experiences of high noise levels, noise annoyance and need for recovery among open-plan office workers. Method: The study was performed with a cross-sectional design. Need for recovery was measured with a short version Need for Recovery (NFR) Scale and noise levels and noise annoyance was measured with Noise Annoyance and High Noise Levels in Work Environments. The questionnaire was sent out to 16 workplaces in Sweden and contained responses from 61 employees. Results and conclusions: Hierarchical multiple regression analysis showed a positive association between experienced high noise levels, noise annoyance and NFR. A significant (p < .05) association was found between noise annoyance and NFR, independent of noise levels. However, no significant association was found between noise levels and NFR when both predictors were included in the same model. Results suggest that noise annoyance, compared to noise levels, has a more important impact on NFR. Even if no significant association were found between both predictors and the outcome variable, noise levels might influence the experience of noise annoyance, and therefore also be important for NFR. However prospective studies are needed for causal inferences.

The research objective is to study the development of the noise spectra patterns in the operating area of copy mill operators. The experimental studies have shown that among harmful factors specific to these machines, there is an octave sound pressure level increase up to 15 dB in the idle mode and up to 15 dB under woodworking. These data suggest that the main noise source creating excess over the maximum permissible values is a spindle unit, and in particular, the spindle case. The vibration measurements on the machine carrier system have confirmed the results of the noise monitoring. The main source of the increased vibration levels for these machine tools is spindle rolling-contact bearings.

The estimation of absolute road traffic noise levels without including the effects of meteorology is thought to be a major source of error in the estimation process commonly used in the United States. In response, the Transportation Research Board-sponsored NCHRP 25-52, Meteorological Effects on Roadway Noise, to collect highway noise data under different meteorological conditions, document the meteorological effects on roadway noise propagation under different atmospheric conditions, develop best practices, and provide guidance on how to (a) quantify meteorological effects on roadway noise propagation and (b) explain those effects to the public. The completed project involved collecting and analyzing 35,000 min of sound and meteorological data at 16 barrier and no-barrier measurement positions adjacent to Interstate 17 in Phoenix, Arizona. This report provides information on the data collection and the modeling recommendations. The database assembled is thought to be among the best available in the United States to permit analysis of meteorological effects on roadway noise. The study recommendations will advance the methodology for estimating the meteorological effects on roadway noise in the United States. © National Academy of Sciences: Transportation Research Board 2019.

[ES] La Contaminación Acústica, en la actualidad, es uno de los fenómenos más molestos y contaminantes que padecemos. El ser humano se encuentra expuesto en su día a día con gran afluencia en las urbes y lugares de trabajo. Llega a afectar a la salud de las personas con efectos fisiológicos y/o psicológicos. La molestia que puede llegar a causar este fenómeno no solo depende del nivel sonoro de la propia actividad en desarrollo, sino que también se ve afectado por su estado de ánimo. Hasta hace relativamente poco, no se le ha empezado a dar real importancia, pero ya se empiezan a tomar medidas de control por parte de la Administración y la población empieza a tomar conciencia del problema. Nuestras urbes padecen una falta de espacios libres, existe una gran mayoría de calles estrechas, todo ello sumado a la actividad y comportamiento incívico de algunos de sus ciudadanos, provocan que un gran porcentaje de habitantes se encuentren expuestos a niveles sonoros excesivamente altos. En este proyecto se estudia el efecto acústico que se origina en el Centro Histórico de la ciudad de Gandia, analizando los niveles sonoros actuales de la ciudad y proporcionando mapas acústicos. Además, se crea una comparativa con el estudio del año 2012, y se valora la evolución acústica respecto anteriores estudios llevados a cabo en los años 1985 y 2004., [EN] Noise in cities is nowadays one of the most annoying and polluting phenomenon that we suffer. The human being is exposed in his daily life to high levels of sound pressure, which affects the health of people and may have physiological and/or psychological effects. The discomfort produced by the acoustic pollution depends both on the sound level of the human activity itself and by the mood of the persons. Due to its consequences, this phenomenon has recently started to receive more attention and public administrations are applying measures in order to prevent or correct it. Our cities suffer from a lack of free spaces and have a large number of narrow streets. These two factors, added to the activity and incivic behavior of its citizens, have as a consequence that a high percentage of inhabitants are exposed to excessively high noise levels. In this project, the acoustic environment in the Historical Center of the city of Gandia is studied by analyzing the current levels of sound and providing acoustic maps. This results of this study are compared to those of the project that was carried out in the year 2012, as well as with those of 1985 and 2004, in order to assess the evolution of the acoustic environment in this part of the city.

The estimation of absolute road traffic noise levels without including the effects of meteorology is thought to be a major source of error in the estimation process commonly used in the United States. In response, the Transportation Research Board-sponsored NCHRP 25-52, Meteorological Effects on Roadway Noise, to collect highway noise data under different meteorological conditions, document the meteorological effects on roadway noise propagation under different atmospheric conditions, develop best practices, and provide guidance on how to (a) quantify meteorological effects on roadway noise propagation and (b) explain those effects to the public. The completed project involved collecting and analyzing 35,000 min of sound and meteorological data at 16 barrier and no-barrier measurement positions adjacent to Interstate 17 in Phoenix, Arizona. This report provides information on the data collection and the modeling recommendations. The database assembled is thought to be among the best available in the United States to permit analysis of meteorological effects on roadway noise. The study recommendations will advance the methodology for estimating the meteorological effects on roadway noise in the United States.

A recent work by Kimura et al. (Earth Planets Space 71:27, 2019. https://doi.org/10.1186/s40623-019-1006-x) (hereafter referred to as K19) claims to provide the first observational constraints on the prompt elastogravity signals (PEGS) induced by an earthquake. To make their claim, the authors argue that the observations shown in Vallée et al. (Science 358:1164–1168, 2017. https://doi.org/10.1126/science.aao0746) (hereafter referred to as V17) are spurious and their modeling inaccurate. Here we show that K19’s claim is invalid because it is based on flawed data processing. In fact, K19’s analysis involves an incomplete correction of the instrument response of broadband seismic sensors, which essentially dismisses low-frequency components of the data that are critical for the detection of intrinsically low-frequency signals such as PEGS. As a direct consequence, signals are much more difficult to observe than in V17, where the low part of the signal spectrum is carefully taken into account. This deficient data processing also explains why the signal amplitude reported by K19 after stacking data from multiple stations is lower than the individual signals reported by V17. Moreover, failing to take appropriate measures of data quality control, K19 used signals from low-quality sensors to call into question the signals detected by high-quality sensors. Finally, K19 use an inadequate simulation approach to model PEGS, in which the important effect of the ground acceleration induced by gravity changes is ignored. In summary, K19 do not show any viable arguments to question the observations and modeling of PEGS presented in V17.

This study is related to distribution temperature sensing (DTS) in sewers for tracing illicit or unintended inflows to foul sewers. A DTS measurement is performed with a fiber optic cable that is installed at the invert of a sewer pipe in combination with a standalone laser/computer instrument. This set-up generates in-sewer temperature measurements with high resolutions in time (every minute) and space (every metre) along the cable over long periods of time (weeks on end). The prolonged monitoring period in combination with the high level of detail in the dataset allows the study of anomalies (i.e., unexpected temperatures and/or temperature variations at certain locations), even if these only occur very infrequently. The objective of this paper is to develop an automated tool to analyze the large data masses and identify anomalies caused by illicit or unintended inflows. In this study, an algorithm for detecting the temperature changes that are caused by both wastewater discharge and inflow of stormwater are developed. A comparison of the results of the automated procedure to the results of a manual assessment of the datasets (Elmehaven, Denmark) shows that the automated procedure performs very well.

The growing demand for renewable energy supply stimulates a drastic increase in the deployment rate of offshore wind energy. Offshore wind power generators are usually supported by large foundation piles that are driven into the seabed with hydraulic impact hammers or vibratory devices. The pile installation process, which is key to the construction of every new wind farm, is hindered by a serious by-product: the underwater noise pollution. This paper presents a comprehensive review of the state-of-the-art computational methods to predict the underwater noise emission by the installation of foundation piles offshore including the available noise mitigation strategies. Future challenges in the field are identified under the prism of the ever-increasing size of wind turbines and the emerging pile driving technologies.

Introduction/Background: The World Health Organization (WHO) considers that noise-related problems can mean health problems. Around 22% of the population in Europe feels affected by the effect of noise. Noise pollution is understood as excess sound that alters the normal conditions of a given area in particular, and of living beings in general. Excess sound is known as noise, which causes noise pollution. Nowadays, the way youths enjoy themselves centres on noise, particularly music, with levels that exceed 100 dBA in leisure areas. Thus noise has become a serious pollution factor and its effects accumulate. Youths more frequently attend these areas who are unaware of the damaging effects of this exposure. The WHO has classified noise effects on the organism into different sections according to their specific effects: Hearing deficiency; Interference in oral communication; Sleep disorders; Physico-physiological effects on mental health and performance; effects on conduct; interference with activities. In relation with the learning process, it has been observed that apart from noise producing impaired hearing among students, it also alters sleep, causes stress and leads to the development of vocal nodules. A series of cognitive effects directly associated with the learning process has also been related given its effect on memory, attention, motivation, and a series of underlying mechanisms and processes. Evaluating the noise level to which university students are exposed in their leisure time has been considered interesting given its implication as a possible barrier against the learning process. Awareness can be raised from the classroom by means of those subjects where these problems to be studied are dealt with; e.g., the Biochemistry subject in Nursing Degree studies. Objective: To know noise levels in the leisure areas to which university students from Albacete (Spain) frequently attend. Method: An observational, descriptive and cross-sectional study that randomly selected 12 leisure areas in the city of Albacete. The dependent variable was the equivalent continuous noise level that students were submitted to in their leisure time, while the independent variables were the places where distributed measurements were taken in turns, defined as evening and nighttime. The instrument that measured the noise levels was a Bruel & Kjaer sound level meter type 2.226, collected in Leq dBA. Results: The mean noise levels measured in the defined turns was 78.7 dBA (SD: 4.14 dBA), with higher levels measured in the nighttime turn with a mean of 83.2 dBA (SD: 9.48 dBA). A statistically significant association between the noise levels measured at weekends and on weekdays (p

The aim of this work is to find the methods of reducing noise and vibration in the belt drive of the electromechanical drive of the selected technological equipment. Thus, we are having more comfortable working conditions in the workplace in compliance with the sanitary standards of noise and vibration. The noise abatement techniques and the simulation of the vibration of the grinding woodworker flexible gearing are considered. Modeling was performed with the introduction of Euler variables. The simulated dependences allow by calculation determine noise levels and load characteristics of the selected equipment. The comparison between the expected noise levels and the sanitary standards allow determining the exceedance and the sources of its generation. All this is the basis for selecting the engineering solutions to observe the noise code.

Tese de Doutoramento, Ciências do Mar (Ecologia Marinha), 31 de março de 2022, Universidade dos Açores. As baleias comum (Balaenoptera physalus), azul (B. musculus) e sardinheira (B. borealis) produzem vocalizações de baixa frequência e grande amplitude que podem ser repetidas num padrão regular, formando canções, ou produzidas de forma irregular, como vocalizações individuais ou em grupo. As canções são produzidas por machos, sobretudo na época de acasalamento, e acredita-se serem usadas como exibições reprodutivas, enquanto as vocalizações irregulares podem ter varias funções associadas a contextos sociais e de alimentação. As técnicas de acústica passiva permitem monitorizar áreas remotas por longos períodos de tempo, possibilitando o estudo dos padrões temporais e espaciais das vocalizações, assim com as suas funções, e elucidando aspetos essenciais da biologia e ecologia destas espécies com elevada mobilidade e elusivas, que de outra maneira seria difícil ou impossível obter. O objetivo principal desta tese é investigar o comportamento vocal das baleias comum, azul e sardinheira (com um foco especial na baleia comum), para adquirir um melhor conhecimento da sua ecologia e comportamento durante a migração, a fase menos conhecida do seu ciclo de vida. Este estudo também investiga os níveis de ruído produzido pelo tráfego marinho em relação ao comportamento vocal destas três espécies, e discute as implicações potenciais para o seu comportamento migratório. […]. ABSTRACT: Fin (Balaenoptera physalus), blue (B. musculus) and sei whales (B. borealis) produce very low frequency and high amplitude vocalisations that can be regularly repeated as songs or irregularly produced as single or grouped calls. While songs are produced by males, peak during the mating season and are believed to act as reproductive displays, calls may have multiple functions associated to feeding and social contexts. By using passive acoustic techniques, that allow long-term continuous monitoring of remote areas, the study of temporal and spatial patterns of vocalisations as well as their functions can elucidate important aspects of the biology and ecology of these highly mobile and elusive species that would otherwise be difficult or impossible to obtain. The main goal of this dissertation is to investigate the vocal behaviour of fin, blue and sei whales (with a special focus on the fin whale), to contribute to a better understanding of their ecology and behaviour during migration, the least known phase of their annual life cycle. This study also investigates shipping noise levels in relation to the vocal behaviour of these three species and discusses potential implications for their migratory behaviour. […]. This thesis was supported by the doctoral grant M3.1.a/F/028/2015 from the Fundo Regional da Ciência e Tecnologia (FRCT). The research stay was funded by the grant FC/FLAD/FMF/CND1/2017/002 of the “Programa Fundo de Mobilidade FLAD-UAc - Crossing the Atlantic”. And co-funded by the following research projects and institutions: TRACE (PTDC/MAR/74071/2006) MAPCET (M2.1.2/F/012/2011) AWARENESS (PTDC/BIA-BMA/30514/2017) MOVE-ON (IF/00943/2013/CP1199/CT0001).

This work investigated the relationships between room acoustics, background noise level, and vocal effort of a speaker in simulated classrooms of various volumes. Under simulated acoustic environments, talkers adjusted their vocal effort linearly with the voice support, i.e., the degree of amplification offered by the room to the voice of a speaker, at his own ears. The slope of this relationship, called the room effect, of -0.24 dB/dB was significant only in the case of the highest noise levels of 62 dB. The vocal comfort for the speaker, however, was found to be more closely related to noise annoyance than to room reverberance. ispartof: Journal of the Acoustical Society of America vol:141 issue:1 pages:EL51-EL56 ispartof: location:United States status: published

LISA Pathfinder is an in-flight test of the local sources of acceleration noise in LISA. The acceleration noise level in LISA Pathfinder is measured by the residual differential acceleration Δg between the two test masses once the coupling to the spacecraft motion has been removed. The full process from raw data to Δg passes through a series of calibration experiments and different data elaboration procedure which are thoroughly used during the mission and represent the baseline for any other further investigation. © Published under licence by IOP Publishing Ltd.

The study of the spectral characteristics of noise levels in the workers of main departments of the enterprises of aluminium and thermal power industries had shown that equivalent sound levels in electrolysis shops at the workplaces of those engaged in electrolysis and anodic production exceeded permissible indicators on 7,1 and 11,8 dBA; in boiler shops of a thermal power station at the workplaces of boiler machinists, machinists-inspectors of boiler equipment and mill machinists the excess in permissible indicators was 22,2 dBA, 21,4 dBA and 29,3 dBA accordingly. It was established that noise in boiler and turbine shops of a thermal power station was broadband and exceeded maximum permissible values in all parts of a spectrum. In the turbine shops of a thermal power station noise levels more often exceeded maximum permissible levels in low- and high-frequency parts of a spectrum.

This paper presents the capacity and SNR (Signal to Noise Ratio) calculation of nano-sensors propagating model inside the human body. The model based on the calculation of path losses and noise level for THz (Terahertz) wave propagation. In the model the channel capacity and SNR are also studied according to transmit power of nano-sensor for future nano-communications inside the human body. According to the transmit power at frequencies based on the calculation results in blood, skin and fat environments show that at the distance of millimeters, the capacity can reach very high values depending on permitted bandwidth, transmit power and environment. © 2016 IEEE.

The emergence of awareness is deeply connected to the process of learning. In fact, by learning that high sound levels may harm one's health, that noise levels that we estimate as innocuous may be dangerous, that there exist an alternative path we can walk to go to work and minimize our exposure to air pollution, etc., citizens will be able to understand the environment around them and act consequently to go toward a more sustainable world.

Part 16: Flexible and Transparent Oxide Electronics; International audience; This work presents an experimental characterization of electrochemically gated graphene field-effect transistors (EGFETs) to measure extracellular cell signals. The performance of the EGFETs was evaluated using cardiomyocytes cells. Extracellular signals with a peak value of 0.4 pico-amperes (pA) embedded in a noise level of 0.1 pA were recorded. Signals in current mode were compared with signals recorded as a voltage. Signals below 28 µV of magnitude can be detected in a noise floor of 7 µV with a signal-to-noise ratio of 4.

The experimental results of th e noise spectra in the floating crane cabins under the sound radiation of the IC e ngine power - plant are presented. The frequency ranges when noise levels in the cabins exceed the sanitary norms are shown.

Nowadays, audio channels in musical concerts (as well as in cabins as in live concerts) start from analogical audio signals generated at microphones, continue with signal transmission to a central audio mixer through wire connections (a wire for each microphone) and end at its digital processing and posterior reproduction through audio system speakers. Algorithm proposed by the authors suggests the signal digitalization directly at microphones and the introduction of virtual audio mixers, which simplifies audio channels management, and reproduces equalization and volume control functions from physical ones, adding control mechanisms over output channels. Noise and attenuation levels are measured and compared with traditional systems, to demonstrate the advantages of using the proposed algorithm.

Conference of 14th IEEE SENSORS ; Conference Date: 1 November 2015 Through 4 November 2015; Conference Code:118927; International audience; The SMSW (Signature Magnification by Selective Windowing) method, based on a temporal processing treat the reflectogram so as to make soft defect signatures detectable. The algorithm first performs a localization of critical points of the reflectogram (zero-crossing or mean-crossing). Then, it selects points having enough energy in both sides (above threshold). This threshold is to be determined statistically or set depending on the application. Once the defect area is windowed, we proceed to the magnification procedure which amplify the defect signature while reducing the noise level on the reflectogram. The proposed method shows very convincing results both in simulation and experiments and for different types of cable and transmission line. We have demonstrated and assessed its applicability on coaxial cables, twisted pair and micro-strip lines. We found that we achieve a gain even with low SNR (Signal to Noise Ratio).

OBJETIVO: Em uma unidade de terapia intensiva, a circulação de pessoas da equipe multidisciplinar e o número considerável de equipamentos e alarmes sonoros deixam o ambiente ruidoso. O objetivo desta pesquisa foi mensurar os níveis de ruídos de uma unidade de terapia intensiva da cidade de Recife e avaliar sua percepção pelos profissionais da unidade. MÉTODOS: Durante uma semana, 24 horas por dia, foi utilizado um decibelímetro para realizar mensurações a cada cinco segundos. Após as aferições, foi aplicado um questionário aos profissionais sobre sua percepção e incômodo causados pelo ruído, e se eles achavam possível reduzir o barulho. RESULTADOS: A média de ruído verificada foi de 58,21 ± 5,93 dB. O período diurno apresentou maiores níveis de ruídos que o noturno (60,86 ± 4,90 vs 55,60 ± 5,98 dB; p < 0,001), assim como os dias úteis quando comparados ao final de semana (58,77 ± 6,05 vs 56,83 ± 5,90 dB; p < 0,001) e a passagem de plantão noturna quando comparada a diurna (62,31 ± 4,70 vs 61,35 ± 5,08 dB; p < 0,001). Dos 73 profissionais que responderam o questionário, 97,3% acham que a unidade de terapia intensiva tem ruído de moderado a intenso, 50,7% se sentem prejudicados pelo barulho e 98,6% acham que é possível reduzir o nível de ruídos. CONCLUSÃO: Os níveis de ruídos encontrados estavam acima dos recomendados. Programas preventivos e educativos conscientizando da importância da redução do nível de ruído devem ser estimulados, envolvendo todos os profissionais que compõem a equipe da unidade de terapia intensiva.OBJECTIVE: The several multidisciplinary team personnel and device alarms make intensive care units noisy environments. This study aimed to measure the noise level of a medical-surgical intensive care unit in Recife, Brazil, and to assess the noise perception by the unit's healthcare professionals. METHODS: A decibel meter was used for continuous every five seconds one week noise levels recording. After this measurement, an interview shaped noise perception questionnaire was applied to the healthcare professionals, approaching the discomfort level and noise control possibilities. RESULTS: Mean 58.21 ± 5.93 dB noise was recorded. The morning noise level was higher than at night (60.85 ± 4.90 versus 55.60 ± 5.98, p

Noise map of city is an instrument for noise control. There are noise levels on all main roads, in people habitation and recreation areas, on the territory of industrial and other enterprises, and around isolated noisy objects. At present time in Russia and abroad the main problem of noise maps is as before the indefinite precision and reliability of indicated value of noise levels. With using of variance analysis method of probability theory and mathematical statistics the authors propose a method which helps in solving this problem.

Este trabalho teve o objetivo de estudar a influência da distribuição de decibelímetros na captação automática dos níveis de pressão sonora, em ambiente de produção intensiva de suínos. O experimento foi conduzido em sala do setor de creche de uma granja comercial de suínos situada no município de Monte Mor, Estado de São Paulo. A sala foi dividida em dez quadrantes idênticos, e os decibelímetros foram instalados no centro geométrico de cada quadrante. Utilizou-se a geoestatística para avaliar a dependência espacial entre os decibelímetros e para predizer os níveis de pressão sonora em locais onde estes não foram instalados. Os dados foram analisados pela correlação entre os decibelímetros e por intermédio da geoestatística, que possibilitou afirmar que não houve dependência espacial entre os pontos de registro dos níveis de pressão sonora. Por intermédio da interpolação dos pontos de captura utilizando o processo de krigagem, foi possível predizer os níveis de pressão sonora nos locais onde não havia decibelímetros no interior da instalação. Verificou-se homogeneidade de propagação dos níveis de pressão sonora no interior da instalação, concluindo que, para o ambiente avaliado, o uso de somente um equipamento para o registro automático dos níveis de pressão sonora é suficiente.The objective of this work was to study the influence of decibelimeters distribution in the automatic acquisition of sound pressure levels in pig nursery facilities. The experiment was conducted in a nursering room of a commercial swine's facility situated in the city of Monte Mor, State of São Paulo, Brazil. The room was divided in ten identical quadrants and the geometrical center of each quadrant was installed the decibelimeters. Geostatistics was used to evaluate the spatial dependence among the decibelimeters and to predict sound pressure levels in the places that they were not installed. Data were analyzed by the correlation among decibelimeters and through geostatistics, being possible to affirm that there was no spatial dependence between recording points of the sound pressure levels. Through interpolation of registration points using kriging process, was possible to predict sound pressure levels in places with no decibelimeters inside the facility. It was verified homogeneity in the sound pressure levels propagation inside the facility, concluding that to the evaluated environment, the use of only one equipment to the automatic registration of sound pressure levels is enough.

To enhance the mobility of combat tracked vehicles, a high-powered compact power pack is crucial. To achieve this goal, it is planned to apply the concept of high-contact-ratio (HCR) gearing to an independent final-drive planetary gear assembly of the tracked vehicle transmission. Before applying the concept to the final-drive, the performances of both normal-contact-ratio (NCR) and HCR conventional parallel shaft spur gearing systems are evaluated and compared. The results show that, for the same torque, HCR gears are subjected to lower loads and endure almost double the life of NCR gears. This reveals that an HCR gear can transmit more power for the same size. Furthermore, the power loss, vibration, and noise level of the HCR gearing are significantly lower than those of the NCR gearing. The proven results of the case study have encouraged the replacement of the existing NCR gearing with the HCR gearing for the final-drive planetary assembly of the combat tracked vehicle for evaluation.

Introduction: Background noise affects the listening environment inside classrooms, especially for younger children. High background noise level adversely affects not only student speech perception but also teacher vocal hygiene. The current study aimed to give an overview of the classroom listening conditions in selected government primary schools in India. Materials and Methods: Noise measurements were taken in 23 classrooms of four government primary schools in southern India, using a type 2 sound level meter. In each classroom measurements were taken in occupied and unoccupied conditions. Teacher voice level was measured in the same classrooms. In addition, the classroom acoustical conditions were observed and the reverberation time for each classroom was calculated. Results: The mean occupied noise level was 62.1 dBA and 65.6 dBC, and the mean unoccupied level was 62.2 dBA and 65 dBC. The mean unamplified teacher speech-to-noise ratio was 10.6 dBA. Both the occupied and unoccupied noise levels exceeded national and international recommended levels and the teacher speech-to-noise ratio was also found to be inadequate in most classrooms. The estimated reverberation time in all classrooms was greater than 2.6 seconds, which is almost double the duration of accepted standards. In addition, observation of classrooms revealed insufficient acoustical treatment to effectively reduce internal and external noise and minimize reverberation. Conclusion: The results of this study point out the need to improve the listening environment for children in government primary schools in India.

In this paper, we consider the problem of identifying the active mode of a switching linear system from data sequences of a finite length. The results combine elements from canonical correlation analysis and subspace projection methods. In addition to providing insight into the geometric meaning of the problem, the results turn out to be of practical relevance whenever mode identification is addressed in the presence of noisy-corrupted measurements. In particular, the results can be used to provide a characterization of the regions of the space where mode identification occurs independently of a prescribed noise level.

The experimental results of noise and vibration in the section of the centrifugal treatment of the helicopter longeron tubes are given. Noise sources determining very high level increase over limitary spectra are identified. As the noise reduction up to the sanitary norms in the source itself is impossible, observing the sanitary standards is possible only through calculating and designing a soundproof construction with the required acoustic protection value. Thus, the noise protection system diagram presenting a safeguard with a high degree of pressurization is given at the end of the paper. The sanitary standards control is achieved as a result of the introduction of the package of measures including the noise enclosure for the facilities of the centrifugal treatment and the sound-absorbing revetment application on the shopfloor walls and the ceiling.

Treball desenvolupat dins el marc del programa 'European Project Semester'. The Acoustic Buoy is a project between the Laboratory of Applied Bioacoustics (LAB) and the Universitat Politècnica de Catalunya (UPC). In areas that the human activities produce high noise levels, such as oil exploration or construction, there is a need to monitor the environment for the presence of cetaceans. Another need is for fishing, to prevent endangered species from being killed. This can be done with an Autonomous Acoustic Buoy (AAB). Mooring or anchoring at to the seafloor can be costly, especially in deep water, for these situations a free floating buoy is required that can monitor the environment and send an alert message when cetaceans are detected nearby or noise levels have exceeded a certain threshold. As an ongoing project different components of the overall concept have been researched and developed, a buoy has been designed, software and hardware have been developed for data acquisition, and a watchdog system has been built to ensure a safe and autonomous unattended operation of the electronics. But one of the key things the overall concept is still missing is the communication system, in short a system needed for transferring the collected data to the end user. Therefore our problem statement is as follows, how can data be transferred from a collecting buoy to the end user and be presented in an accessible and easy to use interface. In order to monitor a large area several autonomous acoustic buoys can be deployed. In order to increase the radio coverage every AAB has the capability of acting as a node in a wireless mesh network so the alarm can automatically find its way to the ship, base or shore point where the end user control station is located. The overall system consists of two parts, the first is the transmission of data between the buoy and the control station and second is the user-interface for displaying alert messages on a map for the end user. Both parts are going to be developed during the European Project Semester 2013

Employees working in cubicles of open-plan offices in Indonesia were studied in regard to their perception on the ability of indoor greenery to reduce noise levels. Sansevieria trifasciata and Scindapsus sp were used. Each was placed in the cubicle and noise levels were measured without plants, with Sansevieria, and with Scindapsus in place. The meters showed very insignificant difference. However, responses to surveys indicated a perception of lower noise in the presence of greenery. This seemed to be supported by prior knowledge and preconception and may be useful in creating a “quieter” indoor environment.

This thesis develops an mathematical non-linear optimization model of flight paths of two aircraft in approach minimizing the perceived noise on the ground while energetic constraint is considered. This is an analytical model of non-linear and non-convex optimal control governed by a system of ordinary differential equations resulting from the dynamics of flight and with their associated constraints. Our contribution focuses on the mathematical modeling equations, optimization and algorithmic programming of an acoustic non-linear optimization model of two aircraft simultaneously on approach. The addressed issues are the mathematical development of the «correct» 3D model, their flight dynamics, the mathematical modeling of the optimal control of dynamic system, the consideration of fuel consumption by aircraft as a differential equation with a consumption function specific variable depending on the evolution of their dynamics, the mathematical modeling of the instantaneous objective function representing the overall noise of the two approaching aircraft. Resolution deals with the direct method of sequential quadratic programming with confidence regions while AMPL programming language and KNITRO are considered. An indirect method was applied under the Pontryagin maximum principle, followed by a Runge-Kutta symplectic partitioned discretization to demonstrate the commutation between the direct approach and indirect approach. The expected results confirm optimal trajectories reducing ground noise and fuel consumption of two aircraft; Cette thèse traite le développement d'un modèle mathématique d'optimisation acoustique des trajectoires de vol de deux avions commerciaux en approche sous contrainte énergétique, aérodynamique et opérationnelle. C'est un modèle analytique de contrôle optimal non-linéaire et non-convexe régi par un système d'équations différentielles ordinaires issues de la dynamique de vol et des contraintes associées. Notre contribution porte sur la modélisation mathématique des équations, l'optimisation et la programmation algorithmique d'un modèle d'optimisation non-linéaire du bruit de deux avions en approche simultanée. Les points abordés sont le développement mathématique du modèle 3D «exact» de leur dynamique de vol, la modélisation mathématique de la commande optimale de ce système dynamique, l'introduction de la consommation du carburant par les avions comme une équation différentielle avec une fonction consommation spécifique variable en fonction de l'évolution de leur dynamique, la modélisation mathématique instantanée de la fonction objectif représentant le bruit global des deux avions en approche. Sa résolution porte sur la méthode directe de programmation séquentielle quadratique avec régions de confiance sous AMPL et KNITRO. Une méthode indirecte a été appliquée sous le principe de maximum de Pontryagin suivie d’une discrétisation de type Runge-Kutta partition-née symplectique d'ordre 4 afin de démontrer la commutation entre l'approche directe et l'approche indirecte. Les résultats obtenus confirment des trajectoires optimales en descente continue, réduisant le bruit au sol ainsi que la consommation de kérosène de deux avions

Physical comfort requirements of users; such as, thermal, visual, and acoustic comfort, should be considered and studied in detail when planning and designing public spaces. However, there is not enough research on the relations between the acoustical parameters, and the acoustic comfort level of users in enclosed non-acoustic public spaces, which are directly connected with a central atrium. In such spaces, evaluation on auditory perception and noise annoyance should be performed in parallel with objective parametric measurements. The food-court area of CEPA Shopping Center, with a central atrium and a glass ceiling structure, in the capital city of Turkey, Ankara is chosen for the case. The aim of this study is to investigate the relationships between the users' subjective ratings of noise levels and the measured equivalent continuous sound pressure levels (Leq). In addition, the demographical differences and user profile variances, as well as the auditory perception classifications are investigated in this case space. The present acoustical indices are measured and then discussed by pointing out the architectural features of the case space, which are the central atrium, glass ceiling structure and the sound reflective material applications. The research methods include, noise measurements to obtain Leq and questionnaires to assess the subjective ratings and auditory perception of the users. This study mainly concentrates on the food-court space, which is within CEPA Shopping Center and displays the significant results regarding this space. These results show that Leq values vary by different day types (weekdays and weekends) and time of day, and the subjective ratings correlate well with these Leq variances. The most dominant sound perceived by the users was found to be the hum of voices. One other significant result implies that, subjective ratings of noise level becomes significant above 67 dBA and shows a sudden increase in the ratings. Furthermore, the time spent in the food-court area correlated significantly with noise annoyance ratings.

This thesis develops an mathematical non-linear optimization model of flight paths of two aircraft in approach minimizing the perceived noise on the ground while energetic constraint is considered. This is an analytical model of non-linear and non-convex optimal control governed by a system of ordinary differential equations resulting from the dynamics of flight and with their associated constraints. Our contribution focuses on the mathematical modeling equations, optimization and algorithmic programming of an acoustic non-linear optimization model of two aircraft simultaneously on approach. The addressed issues are the mathematical development of the «correct» 3D model, their flight dynamics, the mathematical modeling of the optimal control of dynamic system, the consideration of fuel consumption by aircraft as a differential equation with a consumption function specific variable depending on the evolution of their dynamics, the mathematical modeling of the instantaneous objective function representing the overall noise of the two approaching aircraft. Resolution deals with the direct method of sequential quadratic programming with confidence regions while AMPL programming language and KNITRO are considered. An indirect method was applied under the Pontryagin maximum principle, followed by a Runge-Kutta symplectic partitioned discretization to demonstrate the commutation between the direct approach and indirect approach. The expected results confirm optimal trajectories reducing ground noise and fuel consumption of two aircraft, Cette thèse traite le développement d'un modèle mathématique d'optimisation acoustique des trajectoires de vol de deux avions commerciaux en approche sous contrainte énergétique, aérodynamique et opérationnelle. C'est un modèle analytique de contrôle optimal non-linéaire et non-convexe régi par un système d'équations différentielles ordinaires issues de la dynamique de vol et des contraintes associées. Notre contribution porte sur la modélisation mathématique des équations, l'optimisation et la programmation algorithmique d'un modèle d'optimisation non-linéaire du bruit de deux avions en approche simultanée. Les points abordés sont le développement mathématique du modèle 3D «exact» de leur dynamique de vol, la modélisation mathématique de la commande optimale de ce système dynamique, l'introduction de la consommation du carburant par les avions comme une équation différentielle avec une fonction consommation spécifique variable en fonction de l'évolution de leur dynamique, la modélisation mathématique instantanée de la fonction objectif représentant le bruit global des deux avions en approche. Sa résolution porte sur la méthode directe de programmation séquentielle quadratique avec régions de confiance sous AMPL et KNITRO. Une méthode indirecte a été appliquée sous le principe de maximum de Pontryagin suivie d’une discrétisation de type Runge-Kutta partition-née symplectique d'ordre 4 afin de démontrer la commutation entre l'approche directe et l'approche indirecte. Les résultats obtenus confirment des trajectoires optimales en descente continue, réduisant le bruit au sol ainsi que la consommation de kérosène de deux avions

The design, modeling, fabrication, and characterization of a vibrationally trapped thickness-shear MEMS resonator is presented. This device is intended to avoid various limitations of flexural MEMS resonators, including nonlinearity, clamping losses, thermoelastic damping, and high damping in liquid. It includes a silicon bridge and a reference line on an SOI wafer, a coupled Au/Cr coplanar waveguide, Lorentz-force coupling, variations in waveguide thickness for vibrational trapping, and circuitry for nulling the components of the signal that are unrelated to the acoustic resonance. Finite-element vibrational modeling shows the lowest thickness-shear mode with a bridge thickness of 4.9 µm to be dominated by shear displacements, with the magnitude of out-of-plane displacements decreasing with increasing bridge width. Two-dimensional modeling of vibrational trapping, with central regions of the waveguides having 43 nm greater thickness, indicates that amplitudes are reduced by several orders of magnitude at the ends of the bridges for the fundamental ~ 400 MHz thickness-shear resonance. Sweptfrequency network-analyzer measurements of fabricated devices reveal no evidence for an acoustic resonance, despite a calculated prediction of levels of acoustic power absorption that are well above the measured noise level. A possible explanation for this result is stiction of the bridges to the substrate.

Visible mechanical vibrations were noticed on two topsides piping systems on a producing FPSO, in the Gulf of Guinea following increased production in 2008 and 2009. A field survey was undertaken on the piping of the FPSO to investigate the actual pulsation and vibration levels followed by a computer analysis to investigate if fatigue failure, caused by the actual vibrations as measured, would occur. Vibration data was collected from subsea jumpers, risers and topsides piping to ensure full coverage of the flow line systems from the wellhead to production manifolds on the topsides. The objectives of the study were to: determine the root cause of the vibrations, ascertain the vibration levels, predict fatigue occurrence and reduce vibration to acceptable levels. The study revealed that the maximum vibrations levels were caused as a result of an excitation of several mechanical natural frequencies by a broadband excitation as a result of the multiphase flow. The measured vibration levels exceeded the allowable levels in some points of the pipe system which was caused by a very flexible supporting layout. The results of the analysis showed that fatigue failure of the main piping would not occur. However, to avoid failure of small branch connections (e.g. pressure and temperature transmitters) and valves, modifications e.g. additional supports and stiffening of structural steel members, have been advised to achieve acceptable vibration levels to ensure a safe and reliable system in the long term. The measurements, data processing, analysis results and recommendations are discussed in detail.