The motivation for this research was an improvement of the quality of the Earth’s gravity solutions from the GRACE mission data through an instrument-level study. The objective was a better understanding of the characteristics and sources of the highfrequency noise in the range of (0.02 ~ 0.1 Hz) in the dual one-way ranging (DOWR) and its effect on the gravity solution. For this purpose, the mathematical model of the DOWR observation was derived and the Allan variance was computed to establish an upper bound on the level of frequency instability of the ultra-stable oscillators (USO) to determine their contribution to the high-frequency noise. Because they are dominated by the high-frequency noise, the postfit residuals of the time derivative of the DOWR ranges were also examined to evaluate the contributions of various other factors such as system noise from the microwave signal receiver, external influences, and internal influences. The results indicate that the system noise is the dominant source of the excessive highfrequency noise. As one method of mitigation, a tighter bandwidth filter was applied to the DOWR processing, resulting in modest improvements in gravity solutions. / text

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

This thesis describes the first implementation of a colour encoded structured light (CESL) range-finder capable of measuring the shape of time-varying or moving surfaces. The system is shown to have mean square accuracies of better than 0.5mm when measuring the shape of the human mouth during continuous speech sampled at 50Hz, and better than 0.2mm when measuring static objects of similar dimensions. In order to sample range at video-rates, the images of the scene to be digitised are stored on video tape. This allows the image processing to be performed off-line so the sampling rate of the system only depends on the frame-rate of the video equipment used. The work was motivated by the need to acquire information on mouth shape for acoustics of speech experiments so that the results presented are for measurements of mouth shape and objects relating to the field. The reasons for producing a new system, and the choice of CESL are discussed. The work covers the entire implementation of the range-finder, including code and slide design, feature extraction, feature interpretation, calibration and 3D reconstruction, and performance evaluation. A modification on the Blackman and Tukey classical power density spectrum (PDS) estimator was used for feature extraction which was shown to perform better than other techniques evaluated. The accuracy of detected features and the probability that they were not spurious was determined, based on the feature confidence output by the PDS estimator. Detected features were tracked to produce segments, and encoded as a directed acyclic graph (DAG) which was then matched with the original code sequence using a fast but sub-optimal technique. An existing camera calibration technique was used which was extended to include a second step for projector calibration. The projector model used was linear, had the correct number of degrees of freedom, and was particular to our stripe system.

No description available.

Stanford Goldman. / "December 15, 1947." "Presented at the National Electronics Conference, Chicago, Illinois, November, 1947." / Includes bibliographical references. / Army Signal Corps Contract No. W-36-039 sc-32037.

Passive wireless sensor networks (WSNs) are quickly becoming popular for many applications such as article tracking, position location, temperature sensing, and passive data storage. Passive tags and sensors are unique in that they collect their electrical energy by harvesting it from the ambient environment. Tags with charge pumps collect their energy from the signal they receive from the transmitting source. The efficiency of converting the received signal to DC power is greatly enhanced using a power-optimized waveform (POW). Measurements in the first part of this dissertation show that a POW can provide efficiency gains of up to 12 dB compared to a sine-wave input. Tracking the real-time location of these passive tags is a specialized feature used in some applications such as animal tracking. A passive WSN that uses POWs for the improvement of energy-harvesting may also estimate the range to a tag by measuring the time delay of propagation from the transmitter to the tag and back to the transmitter. The maximum-likelihood (ML) estimator is used for estimating this time delay, which simplifies to taking the cross-correlation of the received signal with the transmitted signal. This research characterizes key aspects of performing range estimations in passive WSNs using POWs. The shape of the POW has a directly-measurable effect on ranging performance. Measurements and simulations show that the RMS bandwidth of the waveform has an inversely proportional relationship to the uncertainty of a range measurement. The clutter of an environment greatly affects the uncertainty and bias exhibited by a range estimator. Random frequency-selective environments with heavy clutter are shown to produce estimation uncertainties more than 20 dB higher than the theoretical lower bound. Estimation in random frequency-flat environments is well-behaved and fits the theory quite nicely. Nonlinear circuits such as the charge pump distort the POW during reflection, which biases the range estimations. This research derives an empirical model for predicting the estimation bias for Dickson charge pumps and verifies it with simulations and measurements.

Apresentamos neste trabalho o desenvolvimento de um método para o reconhecimento do Formato de Objetos Tri-dimensionais. Os sistemas tradicionais de Visão Computacional empregam imagens bi-dimensionais obtidos através de câmeras de TV, ricas em detalhes necessários a visão humana. Estes detalhes em grande parte das aplicações industriais de Robôs são supérfluos. Os algoritmos tradicionais de classificação consomem portanto muito tempo no processamento deste excesso de informação. Para este trabalho, desenvolvemos um sistema dedicado para reconhecimento que utiliza um feixe de Laser defletido sobre um objeto e a digitalização da Luminância em cada ponto de sua superfície. A intensidade luminosa refletida e proporcional a distância do ponto ao observador. É, portanto, possível determinar parâmetros que classifiquem cada objeto. A inclinação de cada face de um poliedro, o comportamento de suas fronteiras e também a existência de arestas internas, são as características adotadas. Estas características são então rotuladas, permitindo que o programa de classificação busque em um \"banco de conhecimento\" previamente estabelecido, a descrição dos objetos. Uma mesa giratória permite a rotação do modele fornecendo novas vistas ao observador, determinando sua classificação. Todo o sistema é controlado por um microcomputador cujo programa reconhece em tempo real o objeto em observação. Para o protótipo construído, utilizamos um Laser de HeNe sendo a recepção do raio refletido realizada por um fototransistor. Os objetos reconhecíveis pelo programa são poliedros regulares simples, compondo o seguinte conjunto: 1 prisma de base triangular, 1 cubo, 1 pirâmide de base triangular, 1 pirâmide de base retangular. O tratamento matemático empregado visa a comprovação da tecnologia proposta, podendo, na continuação de trabalhos futuros, ser efetivamente estendido a diversos outros objetos como, por exemplo, os de superfícies curvas. / We present in this work a new method for three dimensional Shape Recognition. Traditional Computer Vision systems use bi-dimensional TV camera images. In most of the industrial Robotic applications, the excess of detail obtained by the TV camera is needless. Traditional classification algorithms spend a lot of time to process the excess of information. For the present work we developed a dedicated recognition system, which deflects a Laser beam over an object and digitizes the Reflected beam point by point over the surface. The intensity of the reflected beam is proportional to the observer distance. Using this technique it was possible to establish features to classify various objects. These features are the slope of the polyhedral surfaces, the boundary type and the inner edges. For each object the features are labeled and the classification algorithm searches in a \"knowledge data base\" for the object description. The recognition system used a He-Ne Laser and the reflected signal was captured by a photo-transistor. The object to be recognized is placed over a rotating table which can be rotated, supplying a new view for the classification. A microcomputer controls the system operation and the object is recognized in real time. The recognized objects were simple regular polyhedral, just as: 1 triangular base prism, 1 cube, 1 triangular base pyramid, 1 rectangular base pyramid. To check that the proposed technology was correct, we used a dedicated mathematical approach, which can be extended to other surfaces, such as curves, in future works.

Apresentamos neste trabalho o desenvolvimento de um método para o reconhecimento do Formato de Objetos Tri-dimensionais. Os sistemas tradicionais de Visão Computacional empregam imagens bi-dimensionais obtidos através de câmeras de TV, ricas em detalhes necessários a visão humana. Estes detalhes em grande parte das aplicações industriais de Robôs são supérfluos. Os algoritmos tradicionais de classificação consomem portanto muito tempo no processamento deste excesso de informação. Para este trabalho, desenvolvemos um sistema dedicado para reconhecimento que utiliza um feixe de Laser defletido sobre um objeto e a digitalização da Luminância em cada ponto de sua superfície. A intensidade luminosa refletida e proporcional a distância do ponto ao observador. É, portanto, possível determinar parâmetros que classifiquem cada objeto. A inclinação de cada face de um poliedro, o comportamento de suas fronteiras e também a existência de arestas internas, são as características adotadas. Estas características são então rotuladas, permitindo que o programa de classificação busque em um \"banco de conhecimento\" previamente estabelecido, a descrição dos objetos. Uma mesa giratória permite a rotação do modele fornecendo novas vistas ao observador, determinando sua classificação. Todo o sistema é controlado por um microcomputador cujo programa reconhece em tempo real o objeto em observação. Para o protótipo construído, utilizamos um Laser de HeNe sendo a recepção do raio refletido realizada por um fototransistor. Os objetos reconhecíveis pelo programa são poliedros regulares simples, compondo o seguinte conjunto: 1 prisma de base triangular, 1 cubo, 1 pirâmide de base triangular, 1 pirâmide de base retangular. O tratamento matemático empregado visa a comprovação da tecnologia proposta, podendo, na continuação de trabalhos futuros, ser efetivamente estendido a diversos outros objetos como, por exemplo, os de superfícies curvas. / We present in this work a new method for three dimensional Shape Recognition. Traditional Computer Vision systems use bi-dimensional TV camera images. In most of the industrial Robotic applications, the excess of detail obtained by the TV camera is needless. Traditional classification algorithms spend a lot of time to process the excess of information. For the present work we developed a dedicated recognition system, which deflects a Laser beam over an object and digitizes the Reflected beam point by point over the surface. The intensity of the reflected beam is proportional to the observer distance. Using this technique it was possible to establish features to classify various objects. These features are the slope of the polyhedral surfaces, the boundary type and the inner edges. For each object the features are labeled and the classification algorithm searches in a \"knowledge data base\" for the object description. The recognition system used a He-Ne Laser and the reflected signal was captured by a photo-transistor. The object to be recognized is placed over a rotating table which can be rotated, supplying a new view for the classification. A microcomputer controls the system operation and the object is recognized in real time. The recognized objects were simple regular polyhedral, just as: 1 triangular base prism, 1 cube, 1 triangular base pyramid, 1 rectangular base pyramid. To check that the proposed technology was correct, we used a dedicated mathematical approach, which can be extended to other surfaces, such as curves, in future works.

La mesure de distance et la détection d'objets sont devenues essentielles dans de nombreux domaines tels que l'automobile ou la robotique, les applications médicales, les procédés industriels et agricoles, les systèmes de surveillance et de sécurité, etc. Dans le but d'améliorer les performances des dispositifs de télémétrie laser en terme de bruit et de diaphonie, une technique hétérodyne par mélange optoélectronique doit être utilisée. Par ailleurs, l'aspect système embarqué nécessite une réduction de l'encombrement et de la consommation à performances égales. L'intégration de mélangeurs optoélectroniques en technologie CMOS apporte donc une solution optimale à cette approche grâce à ses multiples avantages (intégration du circuit d'instrumentation sur la même puce, modèles bien connus, coût raisonnable, performances élevées,…). Ainsi cette thèse traitera de l'étude de mélangeurs optoélectroniques en technologie CMOS pour la télémétrie embarquée haute résolution. Le premier chapitre de ce manuscrit présente les diverses technique de mesure de distance par télémétrie laser par et justifie le choix de la télémétrie laser par déphasage ainsi que le gain en performances lié à l'hétérodynage. Le second chapitre décrit les mélangeurs électriques et optoélectroniques ainsi que les propriétés nécessaires à leur réalisation. Quelques photodétecteurs y sont présentés au vu de la possibilité de les utiliser en mélangeurs optoélectroniques et d'une intégration potentielle en technologie CMOS. Les principales contraintes liées à l'intégration en technologie CMOS de photocapteurs utilisables en mélangeurs optoélectroniques, sont exposés dans la troisième partie. Les travaux de conception et d'optimisation des structures ainsi que les phases de simulations et de test y sont détaillés. Enfin, pour valider expérimentalement les études précédentes, le dernier chapitre présente la conception d'une chaîne de mesure multivoies pour une tête de photoréception CMOS matricée pour un télémètre laser embarqué haute résolution. / Distance measurement and object detection has become essential in many fields such as automotive and robotics, medical applications, industrial processes and farming systems, surveillance and security, etc.. In order to improve the performance of laser ranging devices in terms of noise and crosstalk, an optoelectronic heterodyne technique of mixing should be used. Moreover, the aspect of embedded system requires a reduction in the size and power consumption for the same performance. The integration of optoelectronic mixers in CMOS technology will provide an optimal solution to this approach through its many advantages (integrated instrumentation circuit on the same chip, well-known models, reasonable cost, high performance, ...). Thus this thesis will focus on the study of optoelectronic mixers in CMOS technology for high resolution, embedded laser range finding systems. The first chapter of this thesis discusses the various technique of distance measurement by laser ranging and justifies the choice of phase shift technique and the gain in performance related to heterodyning. The second chapter describes the electrical and optoelectronic mixers and the properties needed to develop them. Some photodetectors are presented given the opportunity to use optoelectronic mixers and a potential integration with CMOS technology. The main constraints to the integration of CMOS photosensors used in optoelectronic mixers are set out in Part III. The work of design and optimization of structures and phases of simulations and testing are detailed. Finally, to experimentally confirm the earlier studies, the final chapter presents the design of a measuring head for a multichannel photoreceptor CMOS for a high resolution laser range finder.

Brasil, país das águas. Este é um pensamento que pode levar a uma despreocupação quanto à conservação da água. Sim, o Brasil possui grandes bacias hidrográficas, mas, por outro lado, possui também regiões que apresentam graves crises de abastecimento. A região amazônica, com apenas 5% da população brasileira, armazena 80% do volume de água de todo o território nacional, enquanto grande parte da população concentra-se nas grandes cidades, exigindo um volume de água cada vez maior. A medição individualizada em edifícios residenciais apresenta-se como um dos meios importantes para combater o desperdício, controlar e reduzir o consumo de água. Este trabalho procura mostrar a medição individualizada como um sistema justo que permite o controle e a redução de água. Numa primeira etapa, foram estudados três edifícios que sofreram reforma, passando do sistema com medição global para o sistema com medição individualizada. Através destes três estudos de casos, foi possível mostrar a distribuição dos apartamentos em classes de consumo, a redução percentual do consumo do edifício e a viabilidade econômica para a execução da reforma. A segunda etapa deste trabalho, compreendeu o acompanhamento da medição por telemetria, associada à medição individualizada, em um edifício residencial. A medição por telemetria permitiu o traçado do perfil de cada consumidor, individualmente, funcionando como uma ferramenta importante para o planejamento de ações que visem ao controle e a redução do consumo de água. / Brazil: a water country. This thought could take the people to forget about water conservation. Although Brazil has big watersheds, it also has regions that present serious water supply crisis. The amazon region, with only 5% of brazilian population, stores 80% of water volume of all national territory, while greater part of the population is concentrated in the big cities, needing, at times, a higher volume of water. The individual measurement in residential buildings is one of the most important ways to prevent water lavishness, also to control and to reduce the water consumption. This work tries to show the individual measurement of water as a fair system of price, which permits the control and the reduction on the water consumption. In the firs part, three buildings that had changed from global measurement system to individual measurement system were studied. By these cases, it was possible to show, in the buildings, the distribution of the apartments in classes of consumption, the percentage reduction and the economic feasibility to perform the modification in the measurement system. The second part of this work was to follow a telemetric measurement system in a residential building with individual water meters. The telemetric measurement allowed to know the profile of each consumer, individually, as an important way to plan actions to control and to reduce the water consumption.