Thesis (M.S.)--State University of New York at Binghamton, Department of Computer Science, Thomas J. Watson School of Engineering and Applied Science, 2007. / Includes bibliographical references.

No description available.

Also published as author's dissertation--Universität Jena, 2005. / Includes bibliographical references.

This thesis was ordered by ÅF Industry in Uppsala with the purpose of improving the standard of Life Cycle Cost-analysis at ÅF. ÅF uses LCC-analysis to show that installing a new lighting system can be cheaper than keeping the existing system. The goal was to create a model in EXCEL that would work on different projects within lighting systems and present the results numerically and graphically. The model was constructed in Excel with the option of comparing up to two different systems, with an existing system, and calculates both economic and environmental gain.

Red interior lighting used to preserve dark-adaptation needs to be replaced in military applications by blue/green lighting which is not detectable by 3rd-generation image intensifiers. This study investigated the influence of blue/green as compared to red and white light of equal photopic intensity on subsequent visual acuity , contrast sensitivity and dark-adaptation. Male subjects (n = 90) were assigned to one of 15 treatment conditions (n = 6) as determined by the colour (blue/green, red or white) and intensity (0.1; 0.4; 1.6; 6.4 and 25.6 cd/m²) of the pre-adaptation stimuli. A modified Goldmann/Weekers adaptometer was used to present the preadaptation stimuli, test stimuli and record visual (luminance) thresholds of each subject. Blue/green lighting had the same affect on visual (photopic) acuity and contrast sensitivity as white and red lighting. Blue/green affected visual (absolute) threshold at the start and during the process of dark-adaptation in the same manner as white but not the same as red lighting. White and red lighting did not differ significantly (p < 0.01) at low intensities (mesopic range) but did at the higher intensities (photopic range). After exposure to blue/green and white light, it will take longer to reach the same level of dark-adaptation than after exposure to red. These time differences increase with" increased intensities. The brightness ratio between red and white lights to produce the same dark-adaptation increases with an increase in intensity. At the upper mesopic region the differences between the effects of white and red lighting on subsequent dark-adaptation become irregular due to the inability to accurately equate non-monochromatic lights in the mesopic range.

Robust localisation is a key requirement for autonomous vehicles. However, in order to achieve widespread adoption of this technology, we also require this function to be performed using low-cost hardware. Cameras are appealing due to their information-rich image content and low cost; however, camera-based localisation is difficult because of the problem of appearance change. For example, in outdoor en- vironments the appearance of the world can change dramatically and unpredictably with variations in lighting, weather, season and scene structure. We require autonomous vehicles to be robust under these challenging environmental conditions. This thesis presents Dub4, a vision-only localisation system for autonomous vehicles. The system is founded on the concept of experiences, where an "experience" is a visual memory which models the world under particular conditions. By allowing the system to build up and curate a map of these experiences, we are able to handle cyclic appearance change (lighting, weather and season) as well as adapt to slow structural change. We present a probabilistic framework for predicting which experiences are most likely to match successfully with the live image at run-time, conditioned on the robot's prior use of the map. In addition, we describe an unsupervised algorithm for detecting and modelling higher-level visual features in the environment for localisation. These features are trained on a per-experience basis and are robust to extreme changes in appearance, for example between rain and sun, or day and night. The system is tested on over 1500km of data, from urban and off-road environments, through sun, rain, snow, harsh lighting, at different times of the day and night, and through all seasons. In addition to this extensive offline testing, Dub4 has served as the primary localisation source on a number of autonomous vehicles, including the Oxford University's RobotCar, the 2016 Shell Eco-Marathon, the LUTZ PathFinder Project in Milton Keynes, and the GATEway Project in Greenwich, London.

Ces dernières années, les diodes électroluminescentes (ou LED) blanches ont connu une forte augmentation de leurs performances ainsi qu'une baisse de coût, faisant de cette technologie la source d'éclairage incontournable des années à venir. Tout comme leur faible consommation en énergie, leur forte durée de vie est un argument de poids pour leur adoption massive dans les solutions d'éclairage. Cependant, cette même durée de vie est l'un des paramètres qui rend l'évaluation de leur fiabilité longue et coûteuse. La multitude de produits proposés, tant au niveau de la puce que du packaging, multiplie les mécanismes de défaillance potentiels et rend donc les études de fiabilité plus difficiles. Ce travail de thèse se concentre l'étude de la fiabilité de ces composants dans son ensemble, depuis les défaillances précoces jusqu'aux défaillances de fin de vie. Dans un premier temps, nous verrons que la mise en place d'un nouveau test de qualification en fin de chaîne de production a permis la caractérisation ainsi que l'amélioration de la détection des défaillances précoces. Le suivi croisé de caractéristiques optiques et électriques au cours de tests accélérés en température et en courant a permis, dans un second temps, d'étudier les défauts aléatoires et les défauts de fin de vie des échantillons. Les résultats statistiques de cette étude ont abouti à la mise en place d'un modèle de variations électro-optiques, permettant une prédiction de la durée de vie plus précise que l'état de l'art actuel. Finalement, l'analyse des échantillons présentant une défaillance durant les tests accélérés a permis la mise en évidence des mécanismes de dégradation majoritairement responsables de la dégradation des échantillons étudiés. Les résultats obtenus permettent une meilleure compréhension de la fiabilité des LED au travers de la modélisation de leur comportement dans le temps et de l'identification de leurs principaux mécanismes de défaillance. La fiabilité des produits étant un élément différenciateur critique, ce travail de thèse est particulièrement utile pour l'industrie des LED. / In the past years, white light emitting diodes (LEDs) have faced an increase of their performances combined with a decrease of their cost. In the present situation, LEDs are considered to be the light source of the future. As well as their low energy consumption, their long lifetime is one argument for a massive adoption of this technology. However, due to their long lifetime and the multitude of existing failure mechanisms (at die and package levels), the study of their reliability still remains challenging. This thesis proposes a wild range study of LED reliability, from early life failures to end of life failures. First, a new qualification test has been implemented in production to characterize and detect early failures of LED. Second, the cross study of electrical and optical variations during accelerated lifetime has been conducted. Results allowed modeling those variations and using this model for more precise lifetime estimations. Finally, failure analyses of aged samples have been conducted highlighting the failures mechanisms responsible for the measured degradations. The obtain results allow a better understanding of LED reliability through the modeling of their behavior during time and the analysis of the most critical failure mechanisms. Because lighting device reliability is a key factor, these results are useful for the LED industry.

Adaptive and smart systems are growing in popularity as we shift toward personalization as a culture. With progressive demands on energy efficiency, it is increasingly important to focus on the utilization of energy in a novel way. This thesis investigates a microelectromechanical system (MEMS) mirror with the express intent to provide flexibility in solid state lighting (SSL). By coupling the micromirror to an optical source, the reflected light may be reshaped and directed so as to optimize the overall illumination profile. In addition, the light may be redirected in order to provide improved signal strength in visible light communications (VLC) with negligible impact on energy demands. With flexibility and full analog control in mind, the design of a fully integrated tip-tilt-piston micromirror with an additional variable focus degree of freedom is outlined. Electrothermal actuators are used to both steer the light and tune the focal length. A detailed discussion of the underlying physics behind composite beams and thermal actuators is addressed. This leads directly into an overview of the two main mirror components, namely the segmented mirror and the deflection actuators. An in-depth characterization of the dynamics of the mirror is discussed including the linearity of the thermal response. Frequency domain analysis of such a system provides insight into tunable mechanical properties such as the resonant frequency and quality factor. The degenerate resonant modes can be separated significantly. It is shown that the frequency response may be tuned by straining specific actuators and that it follows a predictable pattern. As a result, the system can be scanned at increasingly large angles. In other words, coupled mechanical modes allow variable damping and amplification. A means to determine the level of coupling is examined and the mode shape variations are tracked as a function of the tuning parameters. Finally, the applications of such a device are explored and tested. Such applications include reliable signal-to-noise ratio (SNR) enhancements in VLC of 30 dB and color tunable steerable lights using laser diodes. A brief discussion of the implications of dynamic illumination and tunable systems is juxtaposed with an explanation behind the integration of an electrothermal micromirror and an all digital driver.

[pt] A geração de cenas realísticas de fenômenos naturais em tempo real é uma das mais importantes áreas de pesquisa para aplicações em jogos e simuladores. No início da computação gráfica para tempo real, a maioria das aplicações tratava a superfície da água como um plano com uma textura. Essa abordagem produz uma visualizaçãomuito pouco realística da superfície da água, além de não reproduzir o comportamento hidrodinâmico correto da água. Nesse contexto, muitos grupos de pesquisa desenvolveram técnicas para a visualização realística da superfície da água, contudo, a maioria desses trabalhos foca no processo off-line e poucos tratam da questão em tempo real. No entanto, os recentes avanços no desempenho do hardware permitiram a utilização de técnicas tradicionalmente usadas emoff-line para o escopo de tempo real, porém não há uma pesquisa-guia que descreva tais técnicas e faça uma análise comparativa das mesmas. Sendo assim, sem tal pesquisa-guia é muito difícil escolher a melhor técnica para um hardware específico ou se determinada técnica provê o controle de simulação necessário para uma aplicação específica.Nesse contexto, a presente pesquisa analisa as técnicas mais importantes para visualização e simulação de oceano em tempo real, utilizando a unidade de processamento gráfico como o processador principal. Além disso, ela realiza uma análise comparativa de desempenho de cada técnica e estuda os prós e contras delas. Ainda, alguns métodos off-line clássicos são adaptados para uso na GPU. / [en] The synthesis of realistic natural scenes in real time is one of the most important research areas for applications in games and simulators. In the beginning of real-time computer graphics, most of the applications treated water surface as a textured plane. This approach produces a very low realistic rendering of the water surface and does not reproduce the correct hydrodynamics behaviour of the water. So, a lot of research groups developed techniques for realistic water rendering, most of them for off-line processes and a few for real-time use. However, current improvementson hardware performance allow the usage oftraditional off-line techniques for real-time proposes, but there is no research work that describesthese techniques and makes a comparative analysis of them. Then, without this comparative analysis, it is very difficult to choose the best technique for a specific hardware or to decide if a particular technique provides the simulation control that a certain application needs.In this context, the present research work analyses the most important techniques for real-time ocean water simulation and visualization using the graphics processor unit as a main processor. Moreover, it makes a performance comparative analysis of each technique and analyses the pros and cons of them. Furthermore, some classic off-line methods are adapted for GPU use.

This paper discusses the importance and quality of lighting, whether artificial or natural, visual comfort of commercial spaces. The growing importance of shopping centers has made one of its internal areas also stand out: the area intended for hall and circulation, which now is moving beyond the role of rest area. It comes, therefore, a diagnosis of performance in the areas of light and movement hall of a shopping center, located in the city of Maceió / AL, with regard to human needs (visibility and task performance) and architecture. To this end, two major methodological steps have been demarcated. The first step referring to the qualitative assessment by physical survey of the halls and circulation to characterize the system of lighting. The second step is the quantitative evaluation in a sample space and measurement of illuminance second NBR 5382 - Verificação de Iluminâncias de Interiores for artificial lighting systems with posterior simulation for daylighting system and compare the levels found and claimed by the NBR 5413 Iluminância de Interiores and the Building Code and the City of Maceió, municipal law No 5593/2007. These data were crossed resulting in a treatment situation of the lighting at the mall chosen in order: (i) general, where failures were observed in the distribution and height of elements that contribute to the process of reflection of light (natural and artificial) in internal space, and (ii) specific, and there are insufficient Illuminances to the implementation of the planned activities, movement and rest by the mapping curve isolux being situated in two selected sites. There have been made some conclusions in how the daylighting is obtained by first and second floors: the first has Illuminances below the standard in the three simulated points, even at the point below the opening zenith, their highest values ranging from 50lx and 300lx, the second Illuminances has at least four times higher than the values required in the three simulated points, yielding values ranging from 500lx and 7000lx. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho aborda a importância e a qualidade da iluminação, seja ela artificial ou natural, no conforto visual de espaços comerciais. A crescente importância dos shopping centers fez com que uma de suas áreas internas também se destacasse: a área destinada ao hall e circulação, pois agora além do circular há a função de área de descanso. É fornecido, desta forma, um diagnóstico do desempenho luminoso das áreas de hall e circulação de um shopping center, localizado na cidade de Maceió/AL, no tocante às necessidades humanas (visibilidade e desempenho de tarefas) e à arquitetura. Para tal, duas principais etapas metodológicas foram demarcadas. A primeira etapa referindo-se à avaliação qualitativa, mediante levantamento físico dos halls e circulação para caracterizar o sistema da iluminação. A segunda etapa é a avaliação quantitativa em um espaço amostral e aferição da iluminância segundo NBR 5.382 Verificação de Iluminâncias de Interiores para sistemas de iluminação artificial com posterior simulação para o sistema de iluminação natural e comparação entre os níveis encontrados e os solicitados pela NBR 5.413 Iluminância de Interiores e pelo Código de Edificações e Urbanismo da Cidade de Maceió, lei municipal nº 5.593/2007. Estes dados foram cruzados obtendo-se um panorama do tratamento da iluminação no shopping center escolhido de forma: (i) geral, onde foram verificadas falhas na distribuição e altura de elementos que contribuem para o processo de reflexão da luz (natural e artificial) no espaço interno; e (ii) específica, verificando-se iluminâncias insuficientes à realização das atividades previstas, circular e descansar mediante o mapeamento de curvas isolux de duas áreas amostrais. Foram concluídas ainda diferenciações na forma como a iluminação é obtida pelo primeiro e segundo pavimentos: o primeiro possui iluminâncias inferiores à norma nos três pontos simulados, mesmo no ponto abaixo à abertura zenital, seus valores mais altos variando entre 50lx e 300lx; o segundo possui iluminâncias no mínimo quatro vezes acima dos valores solicitados nos três pontos simulados, obtendo-se valores que variaram entre 500lx e 7000lx.