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A acústica submarina vem sendo estudada por décadas, mas redes submarinas com transmissão acústica e protocolos específicos para a comunicação neste meio são campos de pesquisa que estão iniciando. Recentemente alguns simuladores, baseados no NS-2, foram desenvolvidos para o estudo destas redes. Este trabalho avalia através de simulações a viabilidade de aplicações genéricas de monitoramento e controle em redes acústicas submarinas. São propostas e utilizadas três topologias básicas para redes acústicas submarinas: linha, quadro e cubo e dois protocolos MAC: Broadcast e R-MAC. Em nossas análises comparamos esses dois protocolos em relação ao consumo total de energia e o atraso total na rede. Os resultados mostram que essas topologias associadas aos protocolos MAC atendem as necessidades e as peculiaridades da grande maioria das aplicações de monitoramento e controle que utilizam redes acústicas submarinas. O objetivo deste estudo não foi determinar qual a melhor topologia ou o melhor tipo de protocolo de acesso ao meio, mais sim determinar qual a configuração de rede mais indicada para determinada aplicação levando em consideração as características da cada uma delas. / Underwater acoustics has been studied for decades, but underwater networks with acoustic transmission and protocols designed for this environment are just beginning as a research field. Recently some simulators, based on NS-2 have been developed to study these networks. This study evaluates the feasibility through simulations of generic applications for monitoring and control in underwater acoustic networks. Are proposed and used three basic topologies for underwater acoustic networks: line, frame and hub and two MAC protocols: Broadcast and R-MAC. In our analysis we compare these two protocols in relation to the total energy consumption and total delay in the network. The results show that topologies associated with the MAC protocols meet the needs and peculiarities of most monitoring and control applications that use underwater acoustic networks. The objective of this study did not determine the best topology or the best type of MAC protocol, but rather determine which network configuration best suited to particular application taking into account the characteristics of each.

A acústica submarina vem sendo estudada por décadas, mas redes submarinas com transmissão acústica e protocolos específicos para a comunicação neste meio são campos de pesquisa que estão iniciando. Recentemente alguns simuladores, baseados no NS-2, foram desenvolvidos para o estudo destas redes. Este trabalho avalia através de simulações a viabilidade de aplicações genéricas de monitoramento e controle em redes acústicas submarinas. São propostas e utilizadas três topologias básicas para redes acústicas submarinas: linha, quadro e cubo e dois protocolos MAC: Broadcast e R-MAC. Em nossas análises comparamos esses dois protocolos em relação ao consumo total de energia e o atraso total na rede. Os resultados mostram que essas topologias associadas aos protocolos MAC atendem as necessidades e as peculiaridades da grande maioria das aplicações de monitoramento e controle que utilizam redes acústicas submarinas. O objetivo deste estudo não foi determinar qual a melhor topologia ou o melhor tipo de protocolo de acesso ao meio, mais sim determinar qual a configuração de rede mais indicada para determinada aplicação levando em consideração as características da cada uma delas. / Underwater acoustics has been studied for decades, but underwater networks with acoustic transmission and protocols designed for this environment are just beginning as a research field. Recently some simulators, based on NS-2 have been developed to study these networks. This study evaluates the feasibility through simulations of generic applications for monitoring and control in underwater acoustic networks. Are proposed and used three basic topologies for underwater acoustic networks: line, frame and hub and two MAC protocols: Broadcast and R-MAC. In our analysis we compare these two protocols in relation to the total energy consumption and total delay in the network. The results show that topologies associated with the MAC protocols meet the needs and peculiarities of most monitoring and control applications that use underwater acoustic networks. The objective of this study did not determine the best topology or the best type of MAC protocol, but rather determine which network configuration best suited to particular application taking into account the characteristics of each.

A new passive treatment to reduce sound transmission into payload fairing at low frequency is investigated. This new solution is composed of optimally damped vibration absorbers (DVA) and optimally damped Helmholtz resonators (HR). A fully coupled structural-acoustic model of a composite cylinder excited by an external plane wave is developed as a first approximation of the system. A modal expansion method is used to describe the behavior of the cylindrical shell and the acoustic cavity; the noise reduction devices are modeled as surface impedances. All the elements are then fully coupled using an impedance matching method. This model is then refined using the digitized mode shapes and natural frequencies obtained from a fairing finite element model. For both models, the noise transmission mechanisms are highlighted and the noise reduction mechanisms are explained. Procedures to design the structural and acoustic absorbers based on single degree of freedom system are modified for the multi-mode framework. The optimization of the overall treatment parameters namely location, tuning frequency, and damping of each device is also investigated using genetic algorithm. Noise reduction of up to 9dB from 50Hz to 160Hz using 4% of the cylinder mass for the DVA and 5% of the cavity volume for the HR can be achieved. The robustness of the treatment performance to changes in the excitation, system and devices characteristics is also addressed. The model is validated by experiments done outdoors on a 10-foot long, 8-foot diameter composite cylinder. The excitation level reached 136dB at the cylinder surface comparable to real launch acoustic environment. With HRs representing 2% of the cylinder volume, the noise transmission from 50Hz to160Hz is reduced by 3dB and the addition of DVAs representing 6.5% of the cylinder mass enhances this performance to 4.3dB. Using the fairing model, a HR+DVA treatment is designed under flight constraints and is implemented in a real Boeing fairing. The treatment is composed of 220 HRs and 60 DVAs representing 1.1% and 2.5% of the fairing volume and mass respectively. Noise reduction of 3.2dB from 30Hz to 90Hz is obtained experimentally. As a natural extension, a new type of adaptive Helmholtz resonator is developed. A tuning law commonly used to track single frequency disturbance is newly applied to track modes driven by broadband excitation. This tuning law only requires information local to the resonator simplifying greatly its implementation in a fairing where it can adapt to shifts in acoustic natural frequencies caused by varying payload fills. A time domain model of adaptive resonators coupled to a cylinder is developed. Simulations demonstrate that multiple adaptive HRs lead to broadband noise reductions similar to the ones obtained with genetic optimization. Experiments conducted on the cylinder confirmed the ability of adaptive HRs to converge to a near optimal solution in a frequency band including multiple resonances. / Ph. D.

The RoboCup Sony Legged Robot League is an initiative to promote robotics technologies and artificial intelligence in the form of a soccer competition between four-legged robots. The Blekinge Institute of Technology, Royal Institute of Technology, the Universities of ¨ Orebro and Ume°a, competing in the RoboCup domain as Team Sweden , have been participants in the league for three years. To improve the chances of victory in the league, a way to communicate important data between robots is desired. This thesis explores methods for implementing this communication using only the built-in hardware of the robots, i.e. one speaker and two microphones. / david.erman@bth.se

abstract: ABSTRACT This work seeks to develop a practical solution for short range ultrasonic communications and produce an integrated array of acoustic transmitters on a flexible substrate. This is done using flexible thin film transistor (TFT) and micro electromechanical systems (MEMS). The goal is to develop a flexible system capable of communicating in the ultrasonic frequency range at a distance of 10 - 100 meters. This requires a great deal of innovation on the part of the FDC team developing the TFT driving circuitry and the MEMS team adapting the technology for fabrication on a flexible substrate. The technologies required for this research are independently developed. The TFT development is driven primarily by research into flexible displays. The MEMS development is driving by research in biosensors and micro actuators. This project involves the integration of TFT flexible circuit capabilities with MEMS micro actuators in the novel area of flexible acoustic transmitter arrays. This thesis focuses on the design, testing and analysis of the circuit components required for this project. / Dissertation/Thesis / M.S. Electrical Engineering 2012

Les panneaux passifs, en particulier les doubles-cloisons, permettent d’obtenir de bonnes performances en isolation acoustique pour éliminer les bruits indésirables en moyennes et hautes fréquences. Ils ont été largement utilisés dans les domaines du bâtiment ou encore de l’industrie du transport. Un panneau hybride actif/passif est ici étudié, afin d’obtenir de bonnes performances en absorption et en isolation sur une gamme incluant des basses fréquences. La source secondaire est réalisée par une plaque active composée de deux céramiques piézo-électriques collées sur une plaque en acier. Le coeur du double panneau peut inclure un matériau poreux pour améliorer les performances de l’ensemble. Les résultats numériques et les données de mesure montrent que ces panneaux présentent sur une large bande de fréquences de bonnes performances avec contrôle actif. / Passive structures such as double walls are effective at reducing noise transmission at medium and high frequencies. They are widely used in building and transport applications. In this thesis, a hybrid passive/active acoustic panel concept is developped, with the aim of allowing high levels of absorption and insulation over a wide range of frecuencies. The secondary source is realized by an active plate consiting of two piezoelectric patches bonded to an elastic thin plate. The use of porous material as the core of the double-panel improves the acoustic efficiency of the structure. Numerical and experimental results show that this structure presents good absorption and transmission properties thanks to active control.

La sonorité de l’échappement joue un rôle significatif sur le confort acoustique des occupants, ainsi que sur le caractère du véhicule. L’étude proposée porte sur la problématique industrielle suivante : « Description et quantification de la transmission du son entre la bouche d’échappement et l’intérieur du véhicule ». Physiquement la transmission sonore entre l’échappement et l’intérieur du véhicule s’effectue en trois étapes : Propagation des ondes sonores de la canule à la surface extérieure du véhicule et conversion en énergie vibratoire (1) ; Le bruit structurel se propage de la peau extérieure du véhicule à l’habillage intérieur (2) ; La surface intérieure du véhicule rayonne de l’énergie dans l’air à l’intérieur (3). Dans l’état de l’art proposé, la méthode de sous-structuration vibro-acoustique Patch Transfer Functions (PTF) est considérée comme une alternative viable à la problématique proposée. Cependant, avant d’appliquer la méthode sur un véhicule complet, la problématique suivante devait être résolue : « Caractérisation expérimentale d’un sous-système par des mesures sur un système couplé ». Ce manuscrit propose une méthode originale pour mesurer des fonctions de transfert d’un système découplé, sur la base de la réponse d’un système couplé. En raison de la nature mal posée du problème inverse, une méthode originale de régularisation a été proposée. La méthode a été validée pas des essais numériques, puis par un test physique. / Exhaust noise has a significant impact on acoustic comfort and the sound identity of a vehicle brand. The present study focuses on the: “Description and quantification of the sound transmission from the exhaust outlet into the interior of a vehicle”. Physically the noise propagation from the exhaust pipe to the cabin consists of three steps: The sound waves propagate through the air from the exhaust outlet to the external skin of the vehicle (1); the external skin vibrates and transmits its vibration to the internal skin (2); the internal skin radiates sound in the passengers’ cabin (3). The Patch Transfer Functions method, which is based on the framework of dynamic substructuring, allows for the consideration of this complex problem as simpler subproblems that consist of subsystem interactions. Yet the application of the method to a full vehicle requires addressing the problem: “Characterization of Patch Transfer Functions of a subsystem by means of measurement on a coupled system”. This dissertation presents an original inverse method for the measurement of Patch Transfer Functions. In industrial structures, this in-situ characterization is generally the only possible measurement method. Yet, due to the ill posed nature of the problem, the inversion process is difficult. An original regularization method is proposed. The method is tested through numerical simulations, and is validated with an experimental setup.