This thesis details a study of strategies used to limit the flow generated noise encountered in the outlet diffusers of high velocity heating, ventilation and air conditioning (HVAC) duct systems. The underlying noise rating criterion is drawn from the specifications covering ocean going aluminium fast ferries. Although directed primarily towards the fast ferry industry the results presented herein are applicable to other niche high velocity HVAC applications. Experimental tests have been conducted to prove the viability of a high velocity HVAC duct system in meeting airflow requirements whilst maintaining acceptable passenger cabin noise levels. A 50 mm diameter circular jet of air was expanded using a primary conical diffuser with a variety of secondary outlet configurations. Noise measurements were taken across a velocity range of 15 to 60 m/s. An optimum outlet design has been experimentally identified by varying the diffuser angle, outlet duct length and the termination grill. A 4 to 5 fold reduction in required duct area was achieved with the use of a distribution velocity of 20 to 30 ms-1, without exceeding the prescribed passenger cabin noise criteria. The geometric configuration of the diffuser outlet assembly was found to have a pronounced effect on the noise spectrum radiating from the duct outlet. The development of a numerical model capable of predicting the flow induced noise generated by airflow exiting a ventilation duct is also documented. The model employs a Large Eddy Simulation (LES) CFD model to calculate the turbulent flow field through the duct diffuser section and outlet. The flow-generated noise is then calculated using a far field acoustic postprocessor based on the Ffowcs-Williams and Hawkings integral based formulation of Lighthill???s acoustic analogy. Time varying flow field variables are used to calculate the fluctuating noise sources located at the duct outlet and the resulting far field sound pressure levels. This result is then used to calculate the corresponding far field sound intensity and sound power levels. The numerical acoustic model has been verified and validated against the measured experimental results for multiple outlet diffuser configurations.

Bibliography : leaves 237-251. / x, 251 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1994

Darbo tikslas – Įvertinti ar Kauno miesto triukšmo valdymo politika ir taikytos priemonės 2006 – 2013 m. buvo įgyvendintos pakankamai efektyviai, kad apsaugotų gyventojus nuo triukšmo. Uždaviniai: 1. Išanalizuoti triukšmo taršos pokytį Kauno mieste 2006 – 2013 m. 2. Įvertinti Kauno miesto savivaldybės triukšmo valdymo politikos veiksmų ir taikytų priemonių efektyvumą 2006 – 2013 m. Darbo metodai. Teisinių ir operatyvinių dokumentų (vykdytų priemonių planai, Kauno miesto gyventojų skundai, valstybinio audito ataskaitos ir kt.) bei Lietuvos Respublikos ir Europos Sąjungos teisės aktų analizė, pusiau struktūruotas interviu. Antrinių duomenų analizės pagalba išanalizuotas triukšmo pokytis Kauno mieste 2006 – 2013 m. ir įgyvendintų triukšmą mažinančių priemonių efektyvumas. Nustačius esmines problemas ir kompetencijas Kauno miesto savivaldybėje, buvo parengtas pusiau struktūruoto ekspertinio interviu klausimynas, kurio pagalba apklausti specifinės srities ekspertai, darbe tiesiogiai susiduriantys su triukšmo valdymo politikos įgyvendinimu, dirbantys Kauno miesto savivaldybės administracijoje. Rezultatai. Pagrindinė Kauno miesto savivaldybės triukšmo valdymo politikos problema – nepakankamas vietos valdžios dėmesys triukšmo taršai, ši sritis nėra prioritetinė savivaldybės politikos sritis, neįtraukta į Kauno miesto savivaldybės strateginį veiklos planą. 2006 – 2013 m. Kauno miesto savivaldybė triukšmo valdymo įgyvendinimo politikai skyrė 112 tūkst. Lt., 100... [toliau žr. visą tekstą] / Aim of this thesis – to evaluate noise control politics implementation and used measures performance in Kaunas city during the year of 2006 – 2013 in order to ensure healthy environment without noise pollution. Main objectives: 1. To analyze the alteration of noise pollution in Kaunas city in 2006 – 2013 2. To evaluate performance of noise control politics and used measures in municipality of Kaunas city in 2006 – 2013 Work methods. This thesis is based on analysis of European Union and Lithuanian legislation acts, operational documents (strategic planning documents, complaints of the citizens, reports of national audit, etc.). Also a qualitative research method of semi structured interview was used in this thesis. The interview was based on communication (certain questionnaire) with experts who are directly working on noise politics implementation in municipality of Kaunas city. Results and conclusions. The goal of this thesis was reached by combining research of science sources what helped to structure and highlight the main problems such as low level supervision of municipality policy from national governance institutions, no strategic approach to the noise control politics in municipality of Kaunas city, ineffectively used (or even unused) donations. The interview with experts empowered to analyze the situation from the inside of the organization and it showed that noise pollution control in not a subject of priority in municipality of Kaunas city. Inability to... [to full text]

This thesis details a study of strategies used to limit the flow generated noise encountered in the outlet diffusers of high velocity heating, ventilation and air conditioning (HVAC) duct systems. The underlying noise rating criterion is drawn from the specifications covering ocean going aluminium fast ferries. Although directed primarily towards the fast ferry industry the results presented herein are applicable to other niche high velocity HVAC applications. Experimental tests have been conducted to prove the viability of a high velocity HVAC duct system in meeting airflow requirements whilst maintaining acceptable passenger cabin noise levels. A 50 mm diameter circular jet of air was expanded using a primary conical diffuser with a variety of secondary outlet configurations. Noise measurements were taken across a velocity range of 15 to 60 m/s. An optimum outlet design has been experimentally identified by varying the diffuser angle, outlet duct length and the termination grill. A 4 to 5 fold reduction in required duct area was achieved with the use of a distribution velocity of 20 to 30 ms-1, without exceeding the prescribed passenger cabin noise criteria. The geometric configuration of the diffuser outlet assembly was found to have a pronounced effect on the noise spectrum radiating from the duct outlet. The development of a numerical model capable of predicting the flow induced noise generated by airflow exiting a ventilation duct is also documented. The model employs a Large Eddy Simulation (LES) CFD model to calculate the turbulent flow field through the duct diffuser section and outlet. The flow-generated noise is then calculated using a far field acoustic postprocessor based on the Ffowcs-Williams and Hawkings integral based formulation of Lighthill???s acoustic analogy. Time varying flow field variables are used to calculate the fluctuating noise sources located at the duct outlet and the resulting far field sound pressure levels. This result is then used to calculate the corresponding far field sound intensity and sound power levels. The numerical acoustic model has been verified and validated against the measured experimental results for multiple outlet diffuser configurations.

The development of major commercial airports promotes the air transport industry and generates positive economic benefits to the airport and to its host economy. However, external costs are associated with these benefits. Any increase in aircraft movement causes negative environmental impacts, especially noise pollution. Governments have reduced aircraft noise levels at their sources, or introduced aircraft noise management strategies (ANMS); however the problems have never been satisfactorily resolved. This research aims at developing a better understanding of the impacts of aircraft noise on community health and well-being by exploring two core research questions: (1) ???Is health related quality of life worse in communities chronically exposed to aircraft noise than in communities not exposed????; and (2) ???Does long-term aircraft noise exposure associate with adult high blood pressure level via noise stress as a mediating factor????. The Sydney (Kingsford Smith) Airport has been selected as a case study. The health survey instruments have been developed and piloted, and then translated from English into Greek and Arabic. A postal self-administrative health survey (with follow-up letters) has been implemented in the areas surrounding Sydney Airport (called ???aircraft noise exposure group???) and in the matched control group. The total sample size was 1,500 with 47% response rate. This thesis has developed a ???new??? noise index (named Noise Gap Index, NGI) to describe and assess aircraft noise in such a way that is easily understood by the layperson. Factorial analysis of covariance revealed that ???Health related quality of life, in term of physical functioning, general health, vitality, and mental health, of community chronically exposed to high aircraft noise level were worse than the matched control area???. Binary logistic regression analysis found that ???Subjects (aged 15 ??? 87) who have been chronically exposed to high aircraft noise level have the odds of 2.61 of having chronic noise stress. In addition person who have chronic noise stress have the odds of 2.74 of having hypertension compared with those without chronic noise stress???. Finally, the robust hypotheses of effects of aircraft noise on community health and well-being for future experimental study were proposed.

Made available in DSpace on 2014-12-17T13:57:12Z (GMT). No. of bitstreams: 1 DeboraNP_DISSERT.pdf: 3960791 bytes, checksum: 9647ee4242a9677af8d31483a39ab9ab (MD5) Previous issue date: 2013-07-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The Noise Pollution causes degradation in the quality of the environment and presents itself as one of the most common environmental problems in the big cities. An Urban environment present scenario and their complex acoustic study need to consider the contribution of various noise sources. Accordingly to computational models through mapping and prediction of acoustic scene become important, because they enable the realization of calculations, analyzes and reports, allowing the interpretation of satisfactory results. The study neighborhood is the neighborhood of Lagoa Nova, a central area of the city of Natal, which will undergo major changes in urban space due to urban mobility projects planned for the area around the stadium and the consequent changes of urban form and traffic. Thus, this study aims to evaluate the noise impact caused by road and morphological changes around the stadium Arena das Dunas in the neighborhood of Lagoa Nova, through on-site measurements and mapping using the computational model SoundPLAN year 2012 and the scenario evolution acoustic for the year 2017. For this analysis was the construction of the first acoustic mapping based on current diagnostic acoustic neighborhood, physical mapping, classified vehicle count and measurement of sound pressure level, and to build the prediction of noise were observed for the area study the modifications provided for traffic, urban form and mobility work. In this study, it is concluded that the sound pressure levels of the year in 2012 and 2017 extrapolate current legislation. For the prediction of noise were numerous changes in the acoustic scene, in which the works of urban mobility provided will improve traffic flow, thus reduce the sound pressure level where interventions are expected / A Polui??o Sonora provoca degrada??o na qualidade do meio ambiente e se apresenta como um dos mais frequentes problemas ambientais nas grandes cidades. Os ambientes urbanos possuem cen?rios ac?sticos complexos e seus estudos precisam considerar a contribui??o de fontes sonoras diversas. Nesse sentido, os modelos computacionais, por meio do mapeamento e predi??o do cen?rio ac?stico, se tornam importantes, uma vez que possibilitam a realiza??o de c?lculos, de an?lises e de relat?rios que permitem a interpreta??o de resultados satisfat?rios. O bairro de estudo ? o bairro de Lagoa Nova, ?rea central da cidade do Natal, o qual passar? por grandes mudan?as no espa?o urbano devido ?s obras de mobilidade urbana previstas para o entorno do est?dio Arena das Dunas em decorr?ncia da Copa de 2014 e as consequentes mudan?as da forma urbana e no tr?fego. Dessa forma, este trabalho objetiva avaliar o impacto sonoro provocado pelas altera??es vi?rias e morfol?gicas no entorno deste est?dio no bairro de Lagoa Nova em Natal, a partir de medi??es in loco e do mapeamento com a utiliza??o do modelo computacional SoundPLAN no ano 2012 e a evolu??o do cen?rio ac?stico para 2017. Para tal an?lise, realizou-se, primeiramente, a constru??o do mapeamento ac?stico atual com base no diagn?stico ac?stico do bairro, mapeamento f?sico, contagem classificada dos ve?culos e medi??o do n?vel de press?o sonora; e para se construir a predi??o de ru?do, observou-se, para a ?rea de estudo, as modifica??es previstas para o tr?fego, forma urbana e obras de mobilidade. Conclui-se que os n?veis de press?o sonora do ano 2012 e para 2017 extrapolam, em parte, a legisla??o vigente. Para a predi??o do ru?do foram verificadas v?rias modifica??es no cen?rio ac?stico, no qual as obras de mobilidade urbana previstas melhorar?o o fluxo do tr?fego, consequentemente, reduzir?o o n?vel de press?o sonora onde est?o previstas as interven??es

Orientador: Jose Roberto de França Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T11:13:15Z (GMT). No. of bitstreams: 1 Padilha_PauloEduardoFranca_M.pdf: 721382 bytes, checksum: 8fae387ba335cdb5b3e7b462935121c1 (MD5) Previous issue date: 2006 / Resumo: Neste trabalho é feita uma comparação de técnicas analíticas e experimentais de Análise de Caminhos de Transferência Vibroacústicos. A Análise de Caminhos de Transferência, ou TPA como é conhecida pela abreviatura em inglês, é uma ferramenta para se avaliar a contribuição de diferentes caminhos de propagação de energia vibroacústica entre uma fonte e um receptor ligados entre si por várias conexões. Uma aplicação típica de TPA é quantificar e determinar a importância relativa desses caminhos numa dada banda de freqüência, verificando-se a contribuição mais significativa para o receptor. Nessa análise, basicamente duas quantidades devem ser obtidas: as forças operacionais em cada caminho de transferência e a Função de Resposta em Freqüência desses caminhos. Essas funções podem ser obtidas tanto experimentalmente quanto analiticamente, considerando-se ou não a impedância mecânica da fonte vibroacústica. As forças operacionais podem ser diretamente obtidas de medições, usando um transdutor de forças, ou indiretamente estimadas a partir de medições auxiliares. Neste trabalho são apresentados dois métodos de obtenção indireta das forças operacionais ¿ o Método da Rigidez Complexa e o Método da Inversão de Matrizes ¿ associados com as duas possíveis configurações para determinação das Funções de Resposta em Freqüência ¿ incluindo e excluindo a impedância da fonte. Essas técnicas são aplicadas a dois modelos: um analítico e um experimental. avaliadas com esse modelo analítico, comentando-se suas vantagens e desvantagens. São avaliados ainda os efeitos do acoplamento entre fonte e receptor e entre os caminhos de transferência. Os experimentos foram realizados numa estrutura concebida como um modelo simplificado de um automóvel. As forças foram obtidas através dessas duas técnicas indiretas e comparadas com as medidas com transdutores de força. Como no modelo analítico, as forças e FRF foram estimadas na presença e na ausência da fonte, e a contribuição de cada caminho calculada através dessas técnicas e configurações. A resposta do receptor, calculada como uma combinação dos diferentes caminhos de transferência, foi comparada à medida nas condições operacionais, de modo a se verificar a exatidão de cada método utilizado. As vantagens e limitações desses métodos e configurações experimentais são então comentadas para uso em aplicações práticas / Abstract: In the present work, analytical and experimental techniques of Vibro-Acoustic Transfer Path Analysis are compared and discussed. Transfer Path Analysis (TPA) is a tool to evaluate the contribution of different vibro-acoustic energy propagation paths between a source and a receiver linked to each other by a number of connections. TPA is typically used to quantify and rank the relative importance of these paths in a given frequency band, determining the most significant one to the receiver. When applying TPA two basic quantities have to be determined: the operational forces at each transfer path and the Frequency Response Functions of these paths. These functions can be obtained either experimentally or analytically, considering or not the mechanical impedance of the source. Operational forces can be directly measured by force transducers or indirectly estimated from auxiliary response measurements. Two methods to obtain the operational forces indirectly ¿ the Complex Stiffness Method and the Matrix Inversion Method ¿ associated with two possible configurations to determine the Frequency Response Functions ¿ including and excluding the source impedance ¿ are presented and discussed in this work. These estimation techniques are applied to two models: an analytical and an experimental model. Analytically, these techniques are applied to a lumped parameter model. The advantages and drawbacks of them are commented and the effect of coupling between source and receiver and among transfer paths is analyzed with this theoretical approach. The experiments are done in a test structure conceived as a simplified model of an automotive vehicle. The forces are obtained via these two techniques and compared to those measured by force transducers. Like in the analytical model, forces and Frequency Response Functions are estimated in the presence and in the absence of the source, and the contribution of each path is calculated based on the combinations of these different estimation methods and setups. The contributions of the different paths at the receiver location are calculated using each estimation method and are compared to those obtained in the operational condition in order to verify the accuracy of these methods. The advantages and limitations of the methods and test setups are then discussed for use in practical applications / Mestrado / Mecanica Computacional / Mestre em Engenharia Mecânica

This diploma thesis focuses on noise analysis of different integrated circuits used for generating temperature stable reference voltage. All noise contributions are studied separately and there is shown a way of their minimization. Circuit using external capacitor with pre-charging system is chosen as the best solution. Output noise of all analyzed circuits is compared and characteristics of final band-gap reference are summarized at the end of the work.

Objet d’un intérêt tardif dans la recherche universitaire, la musique noise représente pourtant une forme d’art emblématique de l’underground sonore. Elle porte et cristallise une approche radicale en faisant du bruit sa matière, en se jouant de la forme et du développement, en hybridant ses territoires stylistiques. Les pratiques de jeu ne signent plus la suprématie de l’instrument ni de la composition, mais se placent sous le régime d’une expérimentation ludique et bricoleuse. On n’évalue plus la qualité musicale selon le niveau de compétence technique de l’artiste, tandis que les modalités d’écoute sollicitent de manière spécifique le corps et l’environnement. Les pratiques de production, d’organisation et de diffusion de la musique, empruntes de l’éthos du Do it Yourself (DIY) placent l’autonomie, la polyvalence et l’amateurisme au cœur de ce monde de l’art. A partir d’une approche interdisciplinaire marquée par la musicologie, l’esthétique et les sciences sociales, cette thèse entend questionner, à partir d’analyses musicales, d’archives de presse, d’enquêtes, de cartographies et d’une ethnographie menée au sein de la scène parisienne, comment la musique noise et les pratiques sociales qui l’accompagnent nous interrogent sur nos manières conventionnelles d’appréhender ce qu’est la musique et même une « bonne » musique, la figure du musicien, les intermédiaires artistiques ou la scène du concert, au regard de ce qui semble sans doute constituer un nouveau paradigme contemporain de l’expérimentation. / Although noise music has only recently become an object of interest for academic research, it still represents a form of art emblematic of the underground music scene. It is characterized by a radical approach which implies using noise as work material, playing with form and development, and hybridizing its stylistic territories. This approach is reflected by playing practices in which the emphasis is no longer laid on the supremacy of instruments and composition, but rather on playful and makeshift experimentation. Musical quality is not assessed on the artist’s technical skills anymore, while the listening conditions call for a specific implication of both body and environment. The practices of production, organization, and diffusion of music, borrowing from the éthos of DIY, place autonomy, versatility, and amateurism at the heart of this art world. This PhD research, based on musical analyses, press archives, field surveys, topographies, and an ethnographic study of the Parisian scene, proposes an interdisciplinary approach marked by musicology, aesthetics, and social sciences. Its aim is to question the way noise music and its specific social practices challenge the manner in which we conventionally apprehend what we consider as music, and even “good” music, the image of the musician, the artistic intermediaries or the stage, in light of what seems to constitute a new contemporary paradigm of experimentation.

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