Call number: LD2668 .T4 1985 S99 / Master of Arts

Noise is a circumstance of ordinary life and mainly originated by continually growing dynamic and the rapid development of society. In the industrial environment there are noise-intensive parts that influence the condition of present operators negatively. Thus, measures of noise abatement have been investigated intensely by industrial companies as well as federal agencies. As a subdomain of fluid power pneumatics is especially known for characteristic noise emission by the use of air as power transmission. The transient decompression of air from pressure levels up to 8 bar and partly high flow rates nearby sonic speed cause the emergence of direct airborne noise at vent ports of pneumatic components. The following paper outlines the mechanisms that induce the emission of high sound pressure levels. In order to achieve reproducible results a test bench for varying pneumatic standard components is introduced. Based on a selection of those components results are compared to standardized measurement procedures whether fulfilling the standardizations’ requirements. In conclusion, two benefits are achieved. Firstly, standardization is derived enabling neutral comparison of standard pneumatic components’ noise emission. Secondly, the measures can be evaluated to determine the most promising way to redesign pneumatic components of lower noise emissions.

Desmonte de rochas com explosivos em áreas próximas a residenciais têm ocorrido com frequência em várias localidades em todo o Brasil. Atividades relacionadas a mineração e em especial as detonações causam muitos problemas visto que geram incômodo às comunidades vizinhas resultante de níveis elevados de pressão acústica (ruído) na atmosfera e reclamações de rachaduras em paredes das residências associadas com a propagação de vibrações no terreno. A necessidade de se obter uma melhor compreensão de como estruturas típicas da construção civil nacional respondem as vibrações geradas pelas detonações se torna evidente, bem como uma avaliação conjunta da influência de outras forças, tais como, condições meteorológicas (variações diárias de temperatura e umidade relativa do ar) que começam a agir sobre os materiais constituintes das estruturas desde o momento da construção e durante toda sua vida útil. Nesse contexto, definiu-se como meta dessa pesquisa investigar a resposta deformacional de construções de alvenaria frente aos estímulos provocados por diferentes níveis de vibração e pressão acústica gerados pelo desmonte de rochas com explosivos em diferentes condições geológicas, comparando-as com os efeitos das variações climáticas de temperatura e umidade. Visando o atendimento desta demanda, a resposta de três estruturas, duas residenciais e uma comercial, a diferentes operações com desmonte de rochas (mineração de carvão e pedreira) foram avaliadas. A movimentação das paredes de estruturas de alvenaria, comumente encontradas no entorno de empreendimentos mineiros, foi registrada com sensores de velocidade instalados nas paredes e os resultados foram correlacionados com os níveis de vibração no terreno e pressão acústica (ruído) na atmosfera que provocaram esta movimentação. A partir dos resultados das medições da movimentação das estruturas, deformações induzidas nas paredes, geradas durante trações no plano e flexões fora do plano das paredes, foram computadas e comparadas com os limites de ruptura do material mais fraco que constitui as paredes das estruturas. Em conjunto com o monitoramento da movimentação das estruturas, variações na abertura de rachaduras existentes no reboco no interior ou exterior das estruturas induzidas por forças dinâmicas (detonações) e estática (variações climáticas) foram registradas por meio de sensores de deslocamento instalados em ambos lados das rachaduras. As respostas das estruturas apresentaram excelente acoplamento da fundação com o terreno e nenhuma movimentação livre (ressonância) das paredes das estruturas foi observada após a passagem das ondas sísmicas, indicando que as estruturas seguem muito perto as excitações provocadas pelas vibrações no terreno do terreno e param de movimentar junto com o mesmo. Devido às ondas sísmicas e acústicas atingirem quase que ao mesmo tempo as estruturas, foi difícil separar a influência de cada estímulo. As deformações calculadas foram inferiores as necessárias para induzir rachaduras na argamassa utilizada como reboco nas paredes, considerada como o material mais frágil dentre os constituintes das paredes das estruturas. A resposta deformacional das rachaduras frente às variações climáticas diárias de temperatura e humidade relativa do ar foi superior as variações resultantes da influência das vibrações geradas pelas detonações. / Blasting near residential areas has become frequent in many locations throughout Brazil. Activities related to mining and in especial blasting have become a problem as they generate a potential nuisance to nearby communities resulting from high air sound pressure levels and can result in claims of wall cracking associated with ground vibrations. It was deemed necessary to have a better understanding of how structures of typical national construction respond to blast vibrations and compare this response to other forces, such as, environmental forces that naturally act on these structures since the moment they are constructed and throughout the entire life of the structure. The response of three structures, two residential and one office building, to different blasting activities (coal and quarry blasting) were evaluated in this study. Whole structure motions and the movement of existing cracks were measured in masonry built structures commonly found near mining operations. Whole structure and mid-wall motions were measured at upper and lower corners and on mid-walls using single-axis velocity transducers and compared with ground motions and air sound pressure excitations, measured next to the structures using a tri-axial geophone and microphone. Dynamic (blast-induced) and static (weather-induced) changes in crack width of existing interior and exterior wall cracks in the cement grout, typically used as wall coverage, were recorded. Dynamic structure and crack motions during blasting were time-correlated with ground vibrations and air sound pressure levels. Wall strains generated during out-of plane bending and in-plane tensile strains were computed and compared with the failure strains for the weakest material comprising the wall construction. Long-term crack movement with variations in temperature and humidity were compared with blast-induce peak crack displacements. The structures response showed good coupling of the foundations with the ground and no free-response was observed after the cessations of the ground excitations, indicating the structures are rigid following very close the ground excitation. Because air sound pressure levels and ground motions arrived at the same time in the structures, it was difficult to separate the influence of each stimulus. Calculated strains were lower than the required to induce cracks in the cement grout and environmental-induced crack response, resultant from daily changes in temperature and humidity, were greater than the response caused by blast-induced ground motions and air sound pressure levels in crack aperture.

Abstract Noise has become an increasing public health problem and has become serious environment pollution in our daily life. This indicates that it is in time to control and reduce noise from traffic and installations in homes and houses. Today a plethora of products are available for business, but none for the private market. The project describes a start up of development of a sound absorbing wall panel for the private market. It will examine whether it is possible to make a wall panel that can lower the sound pressure level with 3 dB, or reach 0.3 s in reverberation time, in a normally furnished bedroom and still follow the demands of price and environmental awareness. To start the project a limitation was made to use the textiles available per meter within the range of IKEA. The test were made according to applicable standards and calculation of reverberation time and sound pressure level using Sabine’s formula and a formula for sound pressure equals sound effect. During the project, tests were made whether it was possible to achieve a sound classification C on a A-E grade scale according to ISO 11654, where A is the best, with only textiles or if a classic sound absorbing mineral wool had to be used. To reach a sound classification C, a weighted sound absorption coefficient (αw) of 0.6 as a minimum must be reached. The project resulted in that it is technical possible to achieve a sound classification C with only textiles even though for this project another combination was chosen for proceeding with the calculations, because of account to price and environmental awareness. The calculations showed that it is possible to lower the reverberation time to 0.3 s in a normally furnished bedroom with 7 wall panels, and to achieve a lowering of the sound pressure level with 3dB with 7 wall panels. This project showed promising results and leave openings for further research with only textiles and further calculations where more factors are taken under consideration to get more precise and reliable results. / Program: Textilingenjörsutbildningen

Os fatores físicos que envolvem a incubação artificial são determinantes no desenvolvimento embrionário, eclosão e desempenho das aves. Muitos deles são bem-conceituados, mas acredita-se que ainda existem questões que possam prover melhorias ou adaptar este processo as novas demandas da produção animal. Nesta pesquisa, a bioacústica é colocada como uma dessas questões, motivando a investigação da estimulação sonora na incubação artificial, dados os efeitos do ruído dos incubatórios comerciais e a adição de vocalizações da espécie em respostas fisiológicas, produtivas e comportamentais de pintos de corte. Inicialmente, o Capítulo 3 apresenta a mensuração do nível de pressão sonora (NPS) no interior dos ovos. Para isso, desenvolveu-se um sensor de tamanho reduzido (decibelímetro-miniaturizado) utilizando a plataforma Arduíno®. O sensor foi calibrado e testado, o que forneceu informações como o isolamento da onda sonora pela casca dos ovos e valores de NPS próximos aos embriões. Em sequência realizaram-se incubações experimentais com a aplicação de tratamentos determinados pela associação de dois NPS do ruído de incubadoras [70 ou 90 dB (A)] com ou sem a adição de vocalizações da espécie (estímulos naturais). Estes tratamentos foram avaliados no crescimento embrionário e em respostas da eclosão (Capítulo 4) e no desempenho de pintos de corte na primeira semana (Capítulo 5). Diferente do esperado, a exposição ao maior NPS, que simulava o ruído de incubatórios comerciais, adiantou o tempo para o início das eclosões, aumentou a eclodibilidade e a qualidade do umbigo e jarretes dos pintos. Todavia, as vocalizações da espécie só se mostraram influentes se associadas ao NPS de 70 dB (A). Nas respostas de desempenho a exposição ao NPS inferior resultou em um maior consumo de ração e em uma pior conversão alimentar, com melhores resultados na exposição a 90 dB (A) ou na presença das vocalizações. Por fim, no Capítulo 6, testes comportamentais como o de imobilidade tônica, isolamento social e campo aberto foram realizados com os pintos eclodidos dos tratamentos de incubação descritos anteriormente. Na realização destes testes consideraram-se três períodos no pós-eclosão (24, 72 e 120 horas) e duas condições (testes em silêncio ou com vocalizações ao fundo). Os efeitos da estimulação sonora foram verificados somente em 24 horas pós-eclosão, de modo que a exposição às vocalizações no desenvolvimento embrionário reduziu a movimentação e o nível de vocalização dos pintos, o que foi associado ao menor estresse. Conclui-se que a estimulação sonora na incubação artificial é capaz de alterar respostas produtivas e o comportamento de pintos após a eclosão. / The physical factors that involve artificial incubation are determinant to the embryonic development, hatching and performance of chicks. Although many of them are highly regarded, there are other issues capable of improving or adapting the process to new animal-production demands. The current research addresses the bioacoustics as one of such issues, which motivated the investigation of the sound stimuli in artificial incubation, relating the noise of the commercial hatcheries and the addition of vocalizations of the species with physiological, productive and behavioral of chicks. Initially, the Chapter 3 presents the measuring the sound pressure level (SPL) inside eggs. To do so, a small sensor (miniaturized decibel meter) was developed in the Arduino® platform. The sensor was calibrated and tested under specific conditions to collect information, such as sound wave isolation by egg shells and SPL values close to the embryos. Experimental incubations with treatments based on the association between two noise SPLs of the hatcheries [70 or 90 dB (A)] with, or without, the addition of species-specific vocalizations (natural stimulus). These treatments were evaluated on embryo growth and hatch responses (Chapter 4) and chicks performance in the first week of life (Chapter 5). Against all expectations, egg exposure to the highest SPL, which simulated the noise of commercial hatcheries, reduced the time necessary for hatching, besides increasing the hatchability, as well as the quality of the navel and hocks, of chicks. On the other hand, species-specific vocalizations were only influential when they were associated with 70 dB SPL (A). The exposure to lower NPS resulted in higher feed intake and lower feed conversion with better results in exposure to 90 dB (A) or in the presence of vocalizations. Finally, in Chapter 6, behavioral tests such as tonic immobility, social isolation and open field tests applied to chicks hatching from the incubation treatments described above. The tests comprised three post-hatching periods (24, 72 and 120 hours) and two conditions (silence or species-specific vocalizations in the background). The effects of incubation treatments were just observed in some responses and 24 hours after hatching. The exposure to the vocalizations during embryonic development reduced chicks\' movement and vocalization level, which was associated with lower stress. It is concluded that sound stimulation in hatcheries can alter productive responses and behavior of chicks after hatching.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 255-256. / by Thomas Joseph Lynch III. / Ph.D.

<p>Disertacija obuhvata opis osnovnih pojmova i metoda merenja iz oblasti muzičke akustike, detaljnije razrađeni teorijski model pona&scaron;anja zvučnog talasa u cevi frule i detaljnu analizu frekvencijskog spektra tonova odsviranih na jednodelnim i dvodelnim frulama, na glavi dvodelnih frula i tonova dobijenih upotrebom različitih vrsta prigu&scaron;ivača.</p> / <p>The dissertation presents a description of the Musical acoustics basic facts and<br />measuring methods , a profoundly developed theoretical model of behaviour of sound waves in sheperd&#39;s flute, and very detailed frequency spectrum analysis of musical tones played on simple Serbian flute, two-piece Serbian flute, tones played only on the had of the flute and musical tones played on the two-piece Serbian flute using different typesof mutes.</p>

[by] R.D. Maurer [and] Melvin A. Herlin. / Bibliography: p. 6. / Army Signal Corps Contract No. W-36-039 sc-32037, Project no. 102B. Dept. of the Army Project No. 3-99-10-022.

Today Atlas Copco Rock Drills AB hasn’t got any method to determine how many warning alarms they need on their machines and how they should be mounted to use their full potential. At the moment a travel alarm is usually placed in the front of the machine and a reverse alarm in the back. Then a measurement of the sound pressure level around the machine is performed to see if it is enough to pass the limit according to different ISO-standards. Otherwise they have to mount some extra alarms and then do the measurements again until the standards are fulfilled. The aim of this thesis work is to develop a method for determine how many alarms Atlas Copco Rock Drills AB need on the machines, and also how they should be mounted to fulfil the different criteria according to ISO-standards in the early phase of construction. From the different divisions within Atlas Copco Rock Drills AB (LHD, SDE and TME) arrived four different alarms, which are used on their machines. Sound pressure level measurements were conducted on these, in the anechoic chamber at audiological research centre at the university hospital in Örebro. In the LMS Test.Lab software a measurement sphere was built around the horns and based on the data obtained at the anechoic chamber sound directivity plots were made. Together with earlier machine measurement data from Atlas Copco Rock Drills AB, an Excel program was made constituting an example of how the horns should be mounted. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipment / Idag har Atlas Copco Rock Drills AB inte någon metod för att bestämma hur många varningsalarm som behövs på sina maskiner samt var de ska placeras så de utnyttjar sin fulla potential. I nuläget monteras ett signalhorn vid främre delen och ett backlarm i bakre delen av maskinen. Sedan utförs en ljudtrycksmätning runt maskinen för att kontrollera om man uppfyller kraven från olika ISO-standader. Annars monteras fler alarm och mätningen utförs på nytt tills standarderna uppfylls. Detta examensarbete har som mål att ta fram en metod som bestämmer hur många alarm Atlas Copco Rock Drills AB behöver på sina maskiner, samt hur de skall placeras för att uppfylla kriterierna från olika ISO-standarder redan i konstruktionsstadiet.  Från de olika avdelningarna inom Atlas Copco Rock Drills AB (LHD, SDE och TME) mottogs fyra olika alarm, som används på maskinerna. På dessa utfördes ljudtrycksmätningar i det ekofria rummet vid audiologiskt forskningscentrum på universitetssjukhuset i Örebro. I programmet LMS Test.Lab byggdes en sfär av mätpunkter runt alarmen och baserat på insamlade data från det ekofria rummet konstruerades direktivitetsdiagram. Tillsammans med data som Atlas Copco Rock Drills AB redan hade från tidigare mätningar på maskiner gjordes ett Excel-program, som ger ett exempel på hur alarmen bör monteras. LHD = Loaders and trucks/underground rock excavation SDE = Surface drilling equipment TME = Tunnelling and mining equipment

Sound wave has much better transmission in ocean environment than electromagnetic waves, therefore sonar systems are widely applied in underwater investigations. However, not only the target signal is received by the sonar but also the noise from different directions. The noise will affect the performance of the sonar, so the understanding of ocean ambient is an important issue both in academic study and military applications. The ambient noise data of this research was collected by a passive acoustic recording system deployed in the southwest sea of Taiwan, along with the information of wind velocity in the experimented area. The influence on noise level fluctuations by the variation of the wind velocity was first discussed in light of correlation analysis. The fluctuations were expressed in terms of statistic distribution, mean value, standard deviation in different time series. As results, 500 Hz and 1.5k Hz were saturated by high levels signal from unknown sources in spring and summer, so the average sound levels were higher than in fall and winter, about 10 dB and 5 dB higher for 500 Hz and 1.5k Hz respectively. In seasonal analysis, 2.4k and 3.6k Hz have quite stable the mean levels and their standard deviations were around 3 dB. Especially, the noise level of 3.6 Hz has the least fluctuation throughout the year than any other frequencies analyzed. It was also observed that the noise level was decreased with the increase of frequency. Calculated by linear regression, this research worked out the estimation equation for the ambient noise level at high wind speed. However, the estimated values are higher than the measured data, it is due to the distribution of wind velocity. The wind data in this study was skewed towards the lower velocity, consequently the predicted values were overestimated.