Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / Vita. / Includes bibliographical references. / Ph.D.

O trabalho visa por meio de um conjunto de imagens fotográficas da Fundação Energia e Saneamento e de outras fontes correlatas do período analisar historicamente a construção da represa Guarapiranga (1906-1909) em Santo Amaro, ao sul da cidade de São Paulo, bem como discutir as alterações da paisagem e as técnicas de engenharia envolvidas no processo. Tratava-se de um empreendimento da canadense The São Paulo Tramway, Light and Power Company Ltd., companhia de força e luz a se instalar no Brasil, em 1899. Para tanto, apresenta-se também a história da ocupação do Estado e as demandas de água e energia na região, sobretudo em fins do XIX e começo do XX / The work aims at historically analyzing the construction of the Guarapiranga dam (1906-1909) in Santo Amaro, south of the city of São Paulo, through a series of photographic images of the Energy and Sanitation Foundation and other related sources. Besides, it intends to discuss the landscape changes promoted by and the engineering techniques employed in the process. It was an enterprise of the Canadian The São Paulo Tramway, Light and Power Company Ltd., company of force and light to be installed in Brazil, in 1899. For this, we also present the history of the State occupation and the demands of water and energy in the region, especially in the late nineteenth and early twentieth centuries

Este estudo visa comprovar a tese de que é possível identificar estratégias de apropriação da luz natural consistentes com o sistema arquitetônico da Arquitetura Moderna que chamamos de Luz Moderna. Esta perspectiva enfoca a luz natural como um elemento de composição da arquitetura tanto quanto um fator técnico. Assim fica ampliado o foco sobre a apropriação da luz natural que deixa de estar submetida apenas aos critérios técnicos e passa a obedecer a todos os demais parâmetros da própria arquitetura seja o sistema construtivo, a forma, a estrutura, seja a restrição de custos ou da legislação. Para tanto foi realizado um levantamento cronológico da invenção e desenvolvimento da Luz Moderna, bem como um comparativo com a arquitetura produzida durante a década de 1990 que visa o reconhecimento de seus desdobramentos e suas influências. / This study holds the thesis that it is possible to identify lighting strategies that are part of the characteristics of Modern Architecture, so much so that we can call them Modern Daylighting. It deals with natural lighting as a consistent element of the architectural system instead of having a exclusively technical approach. We believe that daylighting design obey to broader parameters just as architecture itself. It answers, for instance, to the constructional system, to form and to structure as well as to law or money constraints. To do so, we organized a chronological view of the invention and development of Modern Daylighting and tried to confront it with works produced during the nineties in order to verify its influences nowadays.

Orientador: Ciro Cesar Zanini Branco / Banca: Orlando Necchi Junior / Banca: Carla Ferragut / Resumo: Os efeitos provocados pela variação quantitativa e qualitativa da luz incidente sobre a estrutura das comunidades de macroalgas lóticas em riachos da região Centro-Sul do estado do Paraná foram investigados a partir de experimentos utilizando-se amostradores com substratos artificiais que modulam a quantidade e qualidade da luz incidente. Os resultados reveleram que as respostas das divisões algais isoladamente foram mais claras do que àquelas observadas para as comunidades de macroalgas como um todo. As algas verdes mostraram-se melhores adaptadas as condições com maiores energias luminosas. A espécie de cianobactéria registrou clara preferência por comprimentos de onda mais longos (faixa do vermelho). As algas vermelhas apesar de apresentarem baixos valores de abundância, aparentemente, preferiram condições levemente sombreadas e, como as cianobactérias, apresentaram maiores valores de abundância quando submetidas a luz vermelha. Neste contexto, o aparato fotossintético característico de cada divisão algal parece ser determinante para os seus comportamentos ecológicos, uma vez que desempenham funções adaptativas diante das diferentes condições de luminosidade / Abstract: The effects of light intensity and quality on the structure of lotic macroalgal communities in streams from the mid-southern region of Paraná State were investigated using artificial substrata that simulate different levels of light and specific wavelengths. The results showed that the abundance values of each algal divisions were clearer to that observed to global macroalgae communities. The green algae were better adaptated on higher light energies conditions. The cianobacteria species reported a clear preference to longer wavelengths (red light). Red algae, on the other hand, despite of the low abundance values, apparently prefer lightly shaded conditions and like blue-green algae, they showed better colonization on the red light. In this context, the characteristic photosynthetic apparatus of each division seems to be determinant to the ecological behavior of these communities once they play an important adaptative role face to the different light conditions / Mestre

This thesis considers two types of applications of quantum feedback control; feedback creation of nonclassical states of light, and controlling nonclassical properties of an ensemble of atoms. An electro-optical feedback loop will create an in-loop field with nonclassical photon statistics similar to squeezed light, resulting in fluorescence line-narrowing of a two-level atom coupled to such light. We extend this theory to study a three-level atom coupled to broadband squashed light, and confirm the two-level atom line-narrowing using a more realistic non-Markovian description of the feedback loop. The second type of application utilizes continuous QND measurement of atomic ensembles. If we measure the collective spin, then the system experiences conditional spin squeezing dependent on the measurement results. We show that feedback based on these results can continuously drive the system into the same conditioned state, resulting in deterministically reproducible spin squeezing. If we measure the atom number fluctuations of a BEC, then, due to the nonlinearity of atomic self interactions, this is also information about phase fluctuations. We show that feedback based on this information can greatly reduce the collisional broadening of the linewidth of an atom laser out-coupled from the condensate.

La lumière influence profondément la physiologie humaine, en plus de permettre la vision. Elle constitue le synchronisateur principal des rythmes circadiens et induit des effets physiologiques immédiats. Ces effets concernent des fonctions non-visuelles telles que la régulation du rythme veille/sommeil, de la température corporelle, de fonctions endocrinologiques, de léveil et des performances. Plusieurs études de ces effets réalisées chez lanimal et chez lhomme ont montré limplication dun système de photoréception non-visuel sensible surtout aux courtes longueurs donde (~470nm ; bleu). Ce système utilise les photorécepteurs classiques (cônes et bâtonnets), en plus de cellules ganglionnaires rétiniennes (CGR) intrinsèquement photosensibles, et exprimant la mélanopsine. Ces CGR se connectent à de nombreux noyaux sous-corticaux et corticaux, ce qui suggère un rôle du système non-visuel dans de nombreuses fonctions cérébrales. Cependant, au delà de ces projections rétiniennes directes, les autres régions du cerveau impliquées sont très peu connues. Une étude en tomographie par émission de positons (TEP), réalisée à lUniversité de Liège, a démontré que leffet éveillant dune lumière nocturne intense (>8000lux) pouvait moduler lactivité cérébrale liée à une tâche attentionnelle. Cette étude, ainsi que quelques données dEEG, résume notre connaissance des mécanismes cérébraux impliqués dans le système non-visuel chez lhomme. De plus, la majorité des études sur ces effets ont été entreprises la nuit. Nous avons réalisé trois études en imagerie fonctionnelle par résonance magnétique (IRMf) utilisant des expositions lumineuses diurnes pour mieux caractériser le système cérébral non-visuel chez lhomme. LIRMf bénéficie dune meilleure résolution spatiale et temporelle que la TEP et permet la caractérisation dactivités cérébrales liées à un processus cognitif précis. La première étude met en évidence des réponses cérébrales liées à une tâche attentionnelle avant et après une exposition lumineuse intense (>7000lux) de 21min. Lamélioration de léveil subjectif induite par la lumière est liée à une augmentation de lactivité thalamique. De plus, la lumière augmente lactivité dun réseau de régions corticales impliquées dans la tâche, prévenant les diminutions dactivités observées en obscurité continue. Ces augmentations déclinent en quelques minutes après larrêt de la lumière, en suivant des dynamiques diverses spécifiques à chaque région. Ces premiers résultats suggèrent que, via une modulation de lactivité de structures sous-corticales régulant léveil, la lumière peut promouvoir dynamiquement lactivité corticale de réseaux impliqués dans un processus cognitif non-visuel. La deuxième étude montre que de courtes expositions (18min) à des lumières monochromatiques (3x1013ph/cm2/s) bleues (470nm) ou vertes (550nm) affectent différemment les réponses cérébrales liées à une tâche de mémoire de travail. La lumière bleue augmente les réponses cérébrales ou, du moins, prévient les diminutions observées sous lumière verte dans des cortex pariétaux et frontaux impliqués dans la mémoire de travail, ainsi que dans le thalamus. Ces résultats montrent quune lumière monochromatique peut rapidement influencer les fonctions cognitives et suggèrent que ces effets sont induits via un système de photoréception qui utilise la mélanopsine. La dernière étude répétait, XXX. Ces résultats démontrent quune exposition lumineuse diurne peut moduler lactivité cérébrale non-visuelle liée à deux fonctions cognitives complexes. La lumière agit rapidement en fonction de la région cérébrale et de la longueur donde considérées. Les sensibilités aux différentes longueurs dondes suggèrent limplication dun système de photoréception utilisant la mélanopsine. XXX. Les résultats suggèrent également une implication étendue de la lumière dans la régulation des fonctions cérébrales chez lhomme et soutiennent son utilisation pour contrecarrer la somnolence diurne et traiter des désordres circadiens et psychiatriques.

This thesis seeks to gain a better understanding on operating characteristics of the three primary color light emitting diode (LED). By applying direct, pulse and sinusoidal currents with dimming function on red, green, and blue LEDs, respectively, the operating characteristics are investigated, including electrical characteristics and their effects on the light efficiency, spectral power distribution, chromaticity on each color LED and the resultant color gamut. The analysis reveals that the illumination characteristics intimately relate to the driving current. LEDs that are driven by pulse currents with pulse-width-modulation (PWM) dimming have less color shift than those driven by direct and sinusoidal currents with amplitude modulation dimming. However, the problematic color shifting is not acceptable when LEDs with pulse current are dimmed at a lower level. Based on the investigation results, a dimming scheme with PWM and pulse- amplitude-modulation (PAM) is proposed to correct the chromaticity and hence to improve the color gamut.

This thesis proposes a novel driving circuit of the RGB light emitting diodes (LEDs) for the back-light source of the liquid crystal display. In stead of employing three dc-to-dc converters, a fly-back converter with three secondary windings is used to drive RGB-LED light bars. By adjusting the duty-ratio, the fly-back converter provides compromised voltages to RGB-LEDs in accordance with the operating modes of dimming control, so as to retain current magnitudes within the acceptable values. LEDs of three colors are dimmed by regulating the duty-ratios of three active power switches individually. By changing the ratio of the average currents of the three primary color LEDs, the color temperature range of driving can reach the requests of dimming control. As compared with a consumer product using the conventional driving circuit, the proposed circuit is obviously much simpler with less components and a higher efficiency.

A perfect duality exists between the problem of space-based orbit determination from line-of-sight measurements and the problem of designing an interplanetary autonomous navigation system. Mathematically, these two problems are equivalent. Any method solving the first problem can be used to solve the second one and, vice versa. While the first problem estimates the observed unknown object orbit using the known observer orbit, the second problem does exactly the opposite (e.g. the spacecraft observes a known visible planet). However, in an interplanetary navigation problem, in addition to the measurement noise, the following "perturbations" must be considered: 1) light-time effect due to the finite speed of light and large distances between the observer and planets, and 2) light aberration including special relativistic effect. These two effects require corrections of the initial orbit estimation problems. Because of the duality problem of space-based orbit determination, several new techniques of angles-only Initial Orbit Determination (IOD) are here developed which are capable of using multiple observations and provide higher orbit estimation accuracy and also they are not suffering from some of the limitations associated with the classical and some newly developed methods of initial orbit determination. Using multiple observations make these techniques suitable for the coplanar orbit determination problems which are the case for the spacecraft navigation using visible planets as the solar system planets are all almost coplanar. Four new IOD techniques were developed and Laplace method was modified. For the autonomous navigation purpose, Extended Kalman Filter (EKF) is employed. The output of the IOD algorithm is then used as the initial condition to extended Kalman filter. The two "perturbations" caused by light-time effect and stellar aberration including special relativistic effect also need to be taken into consideration and corrections should be implemented into the extended Kalman filter scheme for the autonomous spacecraft navigation problem.

In the last few years, interest in polymer optical fibers (POF) has increased because of their low cost, easy handling and good flexibility even at large diameters. Moreover, optical cables do not have the problem of electromagnetic interference, which gives, for instance, the problem of cross-talk in copper telephone cables. In the usage of current communication and computer systems the yield has gained a big importance and it has seen from studies that light scattering loss is the only loss, which cannot be eliminated entirely. Besides, this loss causes its attenuation loss intrinsically and determines the lower limit of loss in the POF. In this work, the importance and the dependencies of light scattering were studied, and calculations were done in order to find more appropriate polymer for using as core material of POFs. For this aim, a computer program that calculates the light scattering loss of several amorphous polymers and plots the graph of isotropic scattering loss versus isothermal compressibility and total attenuation loss versus wavelength was written.