Acoustic modems are the basis for emerging undersea wireless communications networks. US Navy Seaweb technology offers an opportunity to perform undersea navigation and tracking by virtue of node-to-node ranging measurements acquired as a by-product of the acoustic communications protocol. A simple localization algorithm is developed and verified with synthetic data and is then tested with an Unmanned Undersea Vehicle (UUV) during an experiment at sea.

Approved for public release; distribution is unlimited / Reissued 30 May 2017 with Second Reader’s non-NPS affiliation added to title page. / The scalar reciprocity equation commonly stated in underwater acoustics relates pressure fields and monopole sources. It is often used to predict the pressure measured by a hydrophone for multiple source locations by placing a source at the hydrophone location and calculating the field everywhere for that source. That method, however, does not work when calculating the orthogonal components of the velocity field measured by a fixed receiver. This thesis derives a vector-scalar reciprocity equation that accounts for both monopole and dipole sources. This equation can be used to calculate individual components of the received vector field by altering the source type used in the propagation calculation. This enables a propagation model to calculate the received vector field components for an arbitrary number of source locations with a single model run for each received field component instead of requiring one model run for each source location. Application of the vector-scalar reciprocity principle is demonstrated with analytic solutions for a range-independent environment and with numerical solutions for a range-independent and a range-dependent environment using a parabolic equation model. / Electronics Engineer, Naval Undersea Warfare Center

Lake trout populations were extirpated from the lower four Great Lakes by 1960 and from Lake Champlain by 1900. The decline of lake trout populations fueled a wave of restoration-based research that spanned the Great Lakes and filled in many of the gaps in our knowledge of lake trout behavior and ecology. However, remarkably little is known about lake trout spawning behavior, even less about sex-specific differences in spawning site use. Lake trout use specific spawning sites, and may return to the same site year after year. More males are caught on spawning sites than females and are present at spawning sites earlier in the spawning season. The focus of this project is to describe the spawning movements of male and female lake trout within and among spawning seasons and spawning sites. I used acoustic telemetry in Lake Champlain to look at specific questions of spawning site fidelity and whether or not there were differences in male and female movements. I hypothesized that males show site fidelity and remain at a preferred site during the spawning season, whereas females 'sample' multiple spawning reefs to maximize their reproductive success. I established an acoustic telemetry array of ten acoustic receivers placed over eight spawning sites and implanted acoustic transmitters (tags) in 44 male and 48 female lake trout over two years. During two spawning seasons, males spent more time on spawning sites than females. Both male and female lake trout that were active on monitored sites during the spawning season selected a single preferred site. There was no difference in the number of sites visited by males and females. Of the lake trout detected during both spawning seasons, most returned to their capture site in the subsequent spawning season, showing evidence of site fidelity. I also developed a binomial rolling residence test (BRR test) to improve the current method of assessing the duration of a fish's residence at a single receiver. I measured daily detection probabilities (DP) at a given distance from a receiver site. The BRR test evaluates a tag's residence every minute by moving a one-hour time window centered on time t across the duration of the data. The daily DPs are incorporated into a binomial test of the null hypothesis that a fish is not within x meters of the receiver at time t. I performed a 48-hour stationary residence test using two onsite tags and two offsite tags and compared the performance of the BRR test to three residence assessment methods found in the literature. The results showed that the BRR test performs better than all of the time-threshold residency evaluations in our 48-hour stationary residence test. We suggest that this method has the potential to advance the field of telemetry by improving the interpretation of telemetry data.

Cavity flow-acoustic resonances may occur when a fluid stream flows past a recessed cavity in a wall. These resonances may lead to high unsteady pressure levels. The resonance involves a coupling between the instability wave which propagates downstream on the shear-layer that spans the open face of the cavity, and acoustic waves that propagate back upstream inside and outside the cavity. These waves are coupled by the scattering processes at the ends of the cavity. Previous theoretical research considered cavities in a wall that bounds an infinite stream. In many of the experiments on cavity resonances, however, the cavity is placed in a side wall of a wind tunnel. When the surrounding wind tunnel walls are not acoustically treated, the resonances can be very strong. My research is a theoretical investigation of the case of a cavity in a side wall of a wind tunnel. Recently, a mode trapping phenomenon has been proposed as an explanation for the very strong cavity resonances in the wind tunnel case. The mode trapping occurs when the critical frequency of a mode in the tunnel-cavity region is slightly lower than the critical frequency of the corresponding mode in the tunnel region. The region between these two critical frequencies is defined as a frequency window. Experiments show that very high pressure levels are observed in these frequency windows. The goal of my research is to develop a global theory of cavity resonances in the wind tunnel geometry. The global theory couples solutions for the instability wave and the acoustic waves through scattering analyses at the ends of the cavity. Resonance frequencies, spatial mode shapes and linear growth rates are predicted. The theoretical predictions are consistent with experimental measurements and demonstrate that the mode trapping phenomenon explains the experimentally observed behavior.

Resumo: Este trabalho tem a finalidade de investigar a incineração de resíduos sólidos na presença de ondas acústicas para incrementar o processo de combustão. Para tanto foi projetado e construído um forno rotativo para incineração de resíduo sólido industrial. Um combustor do tipo sintonizável foi desenvolvido e acoplado ao forno rotativo para indução de oscilações acústicas, além de outros acessórios utilizados no processo de combustão (alimentador de resíduos, ejetor, sonda para análise de gases). Os resultados obtidos mostram que a presença do campo acústico melhora o processo de combustão. Estes resultados foram avaliados principalmente através da análise de gases de combustão, permitindo uma redução da quantidade de combustível utilizado. / Abstract: This work has the objective of investigating the incineration of solid wastes with acoustics oscillations to improve the combustion process. A rotary kiln was designed and built for the research. A tunable combustor was developed and connected to the rotary kiln for induction of the acoustics oscillations. Accessories were also built and used in the combustion process (feeder of waste, air ejector, probe for gas analysis). The results show that the presence of the acoustic field improves the combustion process. These results had been evaluated mainly through the analysis of gas combustion, allowing a reduction of the amount of used fuel. / Orientador: João Andrade de Carvalho Junior / Coorientador: Galdenoro Botura Júnior / Banca: Marco Aurélio Ferreira / Banca: Cristiane Aparecida Martins Andraus / Banca: José Antonio Perrella Balestieri / Banca: Luiz Roberto Carrocci / Doutor

Acoustic levitation is a method which uses sound radiation to suspend matter in a medium. The main use of this phenomenon is for the contactless processing of matter, allowing to manipulate small objects without any solid contact. Contactless processing of matter presents many advantages in, for example, the fabrication of MEMS (microelectromechanical systems) where handling the components is challenging because of their fragile and surface-sensitive characteristics or in the chemical/biological industry when handling high-purity or hazardous materials. Thus, a new device for noncontact linear transportation of small solid objects is presented here. In this device, ultrasonic flexural vibrations are generated along the ring shaped vibrator using two Langevin transducers and by using a reflector parallel to the vibrator, small particles are trapped at the nodal points of the resulting acoustic standing wave. The particles are then moved by generating a traveling wave along the vibrator, which can be done by modulating the vibration amplitude of the transducers. The working principle of the traveling wave along the vibrator has been modeled by the superposition of two orthogonal standing waves, and the position of the particles can be predicted by using finite element analysis of the vibrator and the resulting acoustic field. A prototype consisting of a 3 mm thick, 220 mm long, 50 mm wide and 52 mm radius aluminum ring-type vibrator and a reflector of the same length and width was built and small polystyrene spheres have been successfully transported along the straight parts of the vibrator. / Levitação acústica é um método para suspender matéria em um meio através de pressão de radiação acústica gerada por intensas ondas de som. O principal uso desse fenômeno é na manipulação de partículas sem contato solido. Esse fenômeno tem várias aplicações para pesquisas onde deve ser evitado todo o contato como, por exemplo, na área de biologia, química, e na fabricação de MEMS. Assim, um novo sistema de transporte linear de partículas por levitação acústica está apresentado aqui. Nesse sistema, vibrações flexurais estão geradas em uma placa tipo anel com dois transdutores tipo Langevin, e colocando um refletor paralelo ao oscilador, partículas estão presas no pontos nodais da onda acústica gerada. As partículas estão deslocadas modulando a amplitude dos transdutores. Assim, este trabalho tem como objetivos a modelagem do fenômeno de levitação acústica, o dimensionamento de um protótipo de sistema de transporte linear de partículas por levitação acústica, bem como a fabricação e o controle desse protótipo. Um protótipo consistindo de uma estrutura tipo anel de alumínio de 3 mm de espessura, 220 mm de comprimento e um raio de 52 mm foi fabricado e o transporte de pequenas esferas de isopor foi realizado com êxito nas parte retas do vibrador.

Ultrasonic instruments are used with the aid of an irrigant such as NaOCl in endodontic treatments to remove dentin debris and calculus from infected root canals. This cleaning process may be assisted by various factors, such as acoustic streaming, and the production of radicals and microjets from the collapse of transient cavitation bubbles. The aim of this project is to understand the principal factors affecting the performance of a number of different endosonic files in order to correlate to their cleaning efficiencies. Characterisation includes detecting transient cavitation activity, mapping the areas of cavitation, assessing the file vibration movements and the streaming effects produced by the files. Experiments to assess the cleaning efficiencies of the files include: emulsification, dye removal with a dental irrigant, ink and hydroxyapatite paste removal from model systems designed to mimic the structure of a tooth. The results show that there is a correlation between the sonochemical output and the cleaning efficiencies, and this brings in further study on the possible factors that may affect the production of transient cavitation and the vibration profiles of the endosonic files. Lastly, a series of computational simulation of the acoustic pressure fields from different endosonic files were performed. Correlations of the simulated and experimental results showed the difference in ultrasonic output of the endosonic files is strongly related to their design. This work provides the basis and techniques necessary to perform a comprehensive study on the design of the endosonic files in order to enhance and optimise their cleaning efficiencies during clinical use and to inform future endodontic practice.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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The acoustoelectric effect in graphene and graphene nanoribbons (GNRs) on lithium niobate surface acoustic wave (SAW) devices was studied experimentally. Monolayer graphene produced by chemical vapour deposition was transferred to the SAW devices. The photoresponse of the acoustoelectric current (Iae) was characterised as a function of SAW frequency and intensity, and illumination wavelength (using 450 nm and 735 nm LEDs) and intensity. Under illumination, the measured Iae increased by more than the measured decrease in conductivity, while retaining a linear dependence on SAW intensity. The latter is consistent with the piezoelectric interaction between the graphene charge carriers and the SAWs being described by a relatively simple classical relaxation model. A larger increase in Iae under an illumination wavelength of 450 nm, compared to 735 nm at the same intensity, is consistent with the generation of a hot carrier distribution. The same classical relaxation model was found to describe Iae generated in arrays of 500 nm-wide GNRs. The measured acoustoelectric current decreases as the nanoribbon width increases, as studied for GNRs with widths in the range 200 – 600 nm. This reflects an increase in charge carrier mobility due to increased doping, arising from damage induced at the nanoribbon edges during fabrication. 2 Lastly, the acoustoelectric photoresponse was studied as a function of graphene nanoribbon width (350 – 600 nm) under an illumination wavelength of 450 nm. Under illumination, the nanoribbon conductivity decreased, with the largest percentage decrease seen in the widest GNRs. Iae also decreased under illumination, in contrast to the acoustoelectric photoresponse of continuous graphene. A possible explanation is that hot carrier effects under illumination lead to a greater decrease in charge carrier mobility than the increase in acoustoelectric attenuation coefficient. This causes the measured decrease in Iae.