Thesis (Masters) -- California Institute of Technology, 1952. / Advisor names found in the Acknowledgments pages of the thesis. Title from home page (viewed 05/10/2010). Includes bibliographic references.

Orientador: Ricardo Machado Leite de Barros / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Fisica / Made available in DSpace on 2018-08-04T23:20:39Z (GMT). No. of bitstreams: 1 Russomanno_TiagoGuedes_M.pdf: 659207 bytes, checksum: f6eb82ae9f7c4931ebb8479370ef2f7f (MD5) Previous issue date: 2005 / Resumo: Este trabalho propõe e avalia um novo método de sincronização para câmeras de vídeo utilizando a banda de áudio. O método consiste em gerar e transmitir um sinal de áudio através de radiofreqüência para receptores conectados a entrada de microfone das câmeras inserindo o sinal na banda de áudio. Em um software, a defasagem temporal entre os sinais é calculada e então é utilizada para interpolar as trajetórias das projeções 2D sincronizadas. A validação do método foi baseada em: 1) Análise da defasagem temporal em função do tempo para dois sinais de vídeos. 2) Comparação entre os valores obtidos por leitura em osciloscópio e no método proposto. 3) Estimativa da melhora na acurácia das medidas de distância entre dois pontos fixados sobre um corpo rígido em movimento aplicando o método proposto. Os resultados mostraram que a defasagem temporal varia lentamente em função do tempo (0.15ms/min) e linearmente. Os valores medidos pelo método proposto e por um osciloscópio mostraram-se equivalentes (R2 =0.998), o erro médio quadrado da diferença entre as medidas foi de 0.10 ms e a máxima diferença encontrada foi de 0.31 ms. Aplicando-se o novo método, a acurácia na reconstrução3D teve uma melhora significativa. A acurácia, a simplicidade e a ampla aplicabilidade do método constituem a principal contribuição deste trabalho / Abstract: This work proposes and evaluates a novel method for synchronisation of video cameras using the audio band. The method consists in generating and transmitting an audio signal through radio frequency for receivers connected to the microphone input of the cameras and inserting the signal in the audio band. In a software environment, the phase differences among the video signals are calculated and used to interpolate the synchronous 2D projections of the trajectories. The validation of the method was based on: 1) Analysis of the phase difference changes in function of time of two video signals. 2) Comparison between the values measured with an oscilloscope and by the proposed method. 3) Estimate of the improvement in the accuracy in the measurements of the distance between two markers mounted on a rigid body during movement applying the method. The results showed that the phase difference changes in time slowly (0.150 ms/min) and linearly, even when the same model of cameras are used. The values measured by the proposed method and by oscilloscope showed equivalence (R2 =0.998), the root mean square of the difference between the measurements was 0.10 ms and the maximum difference found was 0.31 ms. Applying the new method, the accuracy of the 3D reconstruction had a statistically significant improvement. The accuracy, simplicity and wide applicability of the proposed method constitute the main contributions of this work / Mestrado / Biodinamica do Movimento Humano / Mestre em Educação Física

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The Anger camera has been used for the last quarter century in many areas of science to image gamma radiation. Some typical applications include medicine, where functionality of organs are studied in vivo, and industrial inspection of fuel rods for nuclear reactors. The standard Anger geometry includes a large scintillation crystal, light guide, photomultiplier array, and analog processing electronics. Even the most modern gamma cameras built today still use the standard Anger design. The work presented here describes an alternative to the standard gamma-camera design that is flexible enough to be used in a wide variety of applications. Especially in single-photon emmission computed tomography (SPECT) applications, the new design has the potential to be more efficient than the standard design. The new design is modular, that is, several small, separate units comprise a system. Each unit consists of a small gamma camera that is optically and electronically independent from other units. The units, called "modular cameras," can be configured around the region of interest so as to provide the maximum amount of information for reconstruction algorithms or direct information to the operator. The theoretical and experimental investigation of this report focuses on the design and construction of the modular cameras. Each modular camera is, in esscence, a small Anger camera. Components of each module include a scintillation crystal, a light guide, and an array of four photomultiplier tubes. Instead of an analog processing network, each module utilizes fast digital circuitry which includes direct analog-to-digital conversion of the photomultiplier signals, a lookup table which maps detector responses to position estimates of the scintillation flashes in the crystal, and an image memory which accumulates the position estimates and forms an image of the radiation incident on the faceplate of the camera. The digital electronics are necessary because analog techniques fail to give satisfactory estimates of scintillation position when the flashes occur near the sides of the crystal. The contents of the lookup table are determined from the statistical properties of the detected signals as a function of scintillation position. Experiments are described in which "best" estimates of position are found by processing data collected from an array of point-source positions in contact with the crystal. Alternative methods for construction of the lookup table are also discussed, which involve computer generation of the estimates. Both maximum-likelihood and mimimum-mean-square-error estimation rules are used, and the results are compared. A mathematical bound on the performance of the estimators is calculated assuming Poisson statistics for the detection process. The bound, which is a Cramer-Rao lower bound, is used to compare module geometries before lookup tables are constructed. A one-dimensional module, which accumulates information along one axis of the faceplate, is designed first. The one-dimensional module provides proof-of-principle evidence for the estimation techniques and is used to determine critical parameters for modular-camera design. The results of the experiments with the one-dimensional camera are extended to two-dimensional designs, which yield position estimates along both axes of the camera faceplate. Several two-dimensional cameras are tested, and an optimum geometry is constructed and tested for spatial resolution and bias of the estimators.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 157-164). / x, 164 leaves, bound ill. 29 cm

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Wireless Sensor Networks (WSNs) are a relatively new technology with many potential applications, including military and homeland security surveillance operations. Accurate classification of WSN contacts has been attempted using various sensor combinations over the past few years, yet video and photographic imagery remain the only choices for attaining context specific contact classification. While cameras have been successfully installed within some WSNs, there are serious limitations to this solution. Most stemming from the scarce power resources, immobility, and small form factor common among conventional WSN nodes. An efficient, low cost answer to this problem involves the use of unmanned aerial vehicles (UAVs) to acquire imagery of WSN contacts. For this system to scale to the wide expanses that WSNs deploy over, UAV contact surveillance operations must be controlled autonomously. The objective of this thesis is to research and implement an autonomous UAV WSN system, where an optimized two-dimensional flight plan is produced in response to WSN contact detection. Flight plans autonomously guide the UAV on a course to either an estimated interception point with the WSN contact or to the instigated WSN cluster, depending upon user input. The event driven application produced in this study functions in the periphery of the Kestrel Autopilot System, communicating flight plans to the UAV through properly crafted Kestrel packets.

Approved for public release; distribution is unlimited. / The Lineate Image Near Ultraviolet Spectrometer (LINUS) is a spectral imager that works in the ultraviolet region of the spectrum. This thesis describes the latest of several steps in the development of this instrument. Due to the narrow field of view of the instrument, 2.5 x 0.5 degrees, an accurate pointing method is necessary; also, a scheme of quality evaluation of the post-processed spectral image is desirable. A way to achieve both goals was developed by designing and implementing the layout for two visual cameras, wide and narrow field of view, and a method to capture the images in order to perform the subsequent comparison with the processed spectral image. Since this is the first time the system is working in full-automated mode, a new wavelength calibration with the emission lines from a platinum hollow cathode lamp was performed and a new response curve for sulfur dioxide (SO2) was taken. Finally, laboratory and outdoor field observations were conducted to test the system integration. / Lieutenant, Chilean Navy