The present thesis reports psychophysical and modeling studies on the spatial properties of visual mechanisms mediating the perception of mirror symmetry in human vision. In a first set of experiments, patterns were filtered for power spectra that decayed with spatial frequency according to variable slopes. Results revealed that symmetry detection is optimal if contrast energy is roughly equated across log-frequency bands (i.e. 1/f2) and that, under such conditions, spatial scales contribute equally and independently to symmetry perception. In a second study, random-noise patterns were filtered for various orientation bands. Results showed that symmetry perception is possible at all orientations, is mediated by oriented mechanisms, and is computed independently in different orientation channels. Data also revealed that the dimensions of the spatial integration region (IR) for symmetry vary with orientation in a way that approximately matches the spatial distribution of information in the stimulus. Finally, symmetry detection was measured for bandpass textures of variable spatial density and variable contrast polarity. For such patterns, it was found that symmetry is computed at a spatial scale proportional to stimulus density and that mechanisms insensitive to contrast polarity (i.e. second-order) are involved in the scale-selection process. / Overall, results from empirical and modeling work revealed an intimate link between symmetry perception and the properties of spatial filters. In particular, I argue that the size of the IR tends to vary such that a fixed amount of information is integrated irrespective of the spatial properties of the stimulus. Implications for the functional architecture of symmetry perception are discussed, and a paradigm for future research in symmetry perception is proposed in which spatial filtering is extended to higher orders of spatial complexity.

Thesis (M.Sc.)--University of Western Australia, 2008.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1951. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 2007. / Title from first page of PDF file (viewed June 1, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Thesis (M.Sc.Eng.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This thesis presents an integrated driver for deformable mirror array based on the architecture proposed in Horenstein, et al's "Ultra-low power multiplexed electronic driver for high resolution deformable mirror systems." The integrated driver consists of numerous high voltage (HV) analog switches connecting the deformable mirror cells, on demand by low-voltage digital control signals, to the HV analog signal line, and a HV power amplifier used to drive the HV analog signal line. The reduction of power consumption is essential in both HV power amplifier and analog switch designs for utilization of deformable mirror systems in space-based applications. In addition to low power design, this work also focuses on the analysis and design of multi-stage amplifier capable to drive large load capacitor, and HV analog switch robust to analog signal noise during OFF state. The specific research contributions of this work include (1) A feed-forward stage in combination with a class B output stage is proposed in the HV multi-stage power amplifier structure to improve the large-signal performance when driving large capacitive load. (2) A low voltage level-shifter and a voltage clamp are added in conventional HV analog switch to reduce the interference from the noisy analog signal line. / 2031-01-01

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / nÃo hà / Esta pesquisa analisa a videoinstalaÃÃo âTrindadeâ, reconhecendo nela aspectos relacionados à composiÃÃo trinitÃria de seus elementos conceituais (trÃades teÃricas, categorizaÃÃo, mÃtodo dialÃtico, teologia trinitÃria) e materiais (equipamentos, modos de geraÃÃo da imagem, fenÃmenos Ãticos e de produÃÃo de cores sintÃticas), alÃm de se estabelecer paralelos da imagem por ela gerada Ãquela produzida pela ferramenta do espelho. / This research analyzes the videoinstallation âTrindadeâ, recognizing in it the aspects of trinitarian composition of their conceptual elements (triads theoretical categorization, dialectical method, trinitarian theology) and materials (equipment, methods of image generation, optical phenomena and the production of synthetic color), and establish parallels between the image generated by it and the image produced by the tool of the mirror.

This study proposes a theory of texture for Elliott Carter's song cycle A Mirror on Which to Dwell. Texture is an important structural aspect of much recent music, as is exemplified in Carter's music. The first chapter is introductory and discusses other textural theories, and the concept of auditory streams. It also provides background to Elizabeth Bishop and to the poems that Carter selected for the cycle, and introduces the song cycle as a whole. The second chapter outlines a textural theory based on streaming. Texture is defined as comprising those contextually defined aspects of sound which lead one to perceive music as consisting of distinct streams. Individual streams are defined by properties, behaviours processes. The ways in which streams are combined, and the changes that occur in the streams during the combinations constitute textural behaviours and processes. The third chapter presents the ways in which textural behaviours and processes can function. They can have symbolic functions by representing personae and actions in the text. They can also have musical functions and thus can play a role in the delineation of form. In the fourth chapter each song in the Mirror cycle is analyzed. Songs that are texturally clear are analyzed first, followed by those that are more texturally complex. Because of the close relationship between text and music in these songs, each analysis starts with a discussion of the text before turning to the music. The main textural features of each song are presented, and then the analytical discussion focuses on form and text-setting. In the conclusion an overview of the songs is presented. The songs, although formally diverse, are similar in many respects. In all of them Carter establishes the important streams, some of which have significant symbolic roles, in the opening measures. The songs are characterized by similar textural processes, which help to delineate the form of the songs and to portray musically the meaning of the text. An analysis of these songs using the textural theory presented in this study provides insight into their form and meaning. / Arts, Faculty of / Music, School of / Graduate

Deformable mirror is a widely used wavefront corrector in adaptive optics system, especially in astronomical, image and laser optics. A new structure of DM-3D DM is proposed, which has removable actuators and can correct different aberrations with different actuator arrangements. A 3D DM consists of several reflection mirrors. Every mirror has a single actuator and is independent of each other. Two kinds of actuator arrangement algorithm are compared: random disturbance algorithm (RDA) and global arrangement algorithm (GAA). Correction effects of these two algorithms and comparison are analyzed through numerical simulation. The simulation results show that 3D DM with removable actuators can obviously improve the correction effects.

This dissertation presents the modeling, design, fabrication, and experimental testing of a polyimide based micro mirror for applications in MEMS logic devices based on its static behavior and in MEMS resonators using mixed frequency excitation. First, a universal MEMS logic device that can perform all the logic operations, such as INVERTER, AND, NAND, NOR, and OR gates using one physical structure, within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. We discuss the fabrication, simulations and experimental results demonstrating these logic operations on a polyimide micro mirror. The device is capable of performing the switching operation with a frequency of 1 kHz, a switching time of 8.2 μs, and an electrical lifetime of 8000 cycles. Second, this study presents an experimental and theoretical investigation of a micro mirror under a mixed frequency signal composed of two harmonic AC sources. The experimental and theoretical dynamics are explored via frequency sweeps in the desired neighborhoods. One frequency is fixed while the other frequency is swept through a wide 5 range to study the dynamic responses of the micro mirror. These responses are studied under different frequencies and different input voltages. The results show interesting dynamics, where the system exhibits primary resonance, and combination resonances of additive and subtractive type. The mixed excitation is demonstrated as a way to increase the bandwidth of the resonator near primary resonance, which can be promising for resonant sensing applications in the effort to increase the signal-noise ratio over extended frequency range. It can be promising for energy harvesting as well; since it provides the system with resonances of very high amplitudes at very low frequencies regardless of what is the natural frequency of the system, however this still needs further investigation.

Cílem této práce je vyvinout aplikaci schopnou dešifrovat zabezpečená spojení a přeposlat dešifrovaná data na jinou stanici v síti pro další analýzu.  Daná aplikace vybízí k nelegálním účelům, avšak zamýšleným použitím výsledného produktu jsou legální odposlechy. Pro tuto práci byla z množiny nástrojů vybrána aplikace SSLsplit díky jejím vlastnostem a výkonnosti. Toto rozhodnutí bylo na základě srovnávacích testů a porovnání vlastností. Pomocí vlastního certifikátu SSLsplit podepisuje certifikáty cílových serverů, které jsou vytvářené za běhu. Spuštěná aplikace běží v režimu transparentní proxy přímo na centrálním prvku dané sítě (routeru). SSLsplit provádí man-in-the-middle útok mezi klientem a serverem bez toho, aby to některá ze stran zaznamenala. Dále umožnuje dešifrovaný obsah odeslat na předem daný uzel v síti pro jeho další zpracování. Pro možnost snažší konfigurace SSLsplitu byla implementována integrace do netc rozhraní. Aplikace byla otestována za účelem zjištění jejich výkonnostních limitů. Výkonnostní testy výsledného řešení ukazují značný pokles počtu transakcí za sekundu (TPS) při použití SSLsplit v porovnání s pouhým přeposíláním provozu. Funkce zrcadlení významně neovlivňuje počet TPS ani neomezuje samotný SSLsplit. Výsledky ukazují, že SSLsplit je schopen reálného provozu s určitým omezením.