Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, February 2016. / Cataloged from PDF version of thesis. "February 2015." / Includes bibliographical references (pages 162-173). / The recent development of neuromorphic vision sensors, which provide an asynchronous, high-speed alternative to conventional cameras has lead to a considerable amount of research into their applicability to robotic control systems. However, algorithms for onboard control of mobile robotic platforms such as automobiles or aircraft using these sensors are lacking and in fact almost all existing implementations keep the sensor stationary. This research has several objectives. First, to develop a rigorous understanding of how to use asynchronous temporal contrast vision sensors for heading regulation and tracking in such a way as to fully leverage the remarkable properties of these sensors including high bandwidth, low latency and low power consumption. Second, to provide a theoretical and experimental comparison between neuromorphic vision sensors and conventional cameras in the context of this problem. Finally, to describe and test algorithms for high-speed motion planning in cluttered environments using neuromorphic vision sensors. / by Erich Mueller. / Ph. D.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 103-105). / In this thesis, a priori convergence estimates are developed for outputs, output error estimates, and localizations of output error estimates for Galerkin finite element methods. Specifically, Continuous Galerkin (CG), Discontinuous Galerkin (DG), and Hybridized DG (HDG) methods are analyzed for the Poisson problem. A mixed formulation for DG output error estimation is proposed with improved convergence rates relative to the common approach utilizing statically condensed, p-dependent lifting operators. The HDG output error estimates are new and include the impact of stabilization. Comparisons to numerical results demonstrate (1) the sharpness of the estimates and (2) that the HDG estimates are approximately an order of magnitude more accurate than CG and DG. / by Hugh Alexander Carson. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1964. / MICROFICHE COPY AVAILABLE IN AERO. / Includes bibliographical references (leaves 93-95). / by David Finkleman. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1990. / Includes bibliographical references (leaves 117-123). / by Michael Joseph Villalba. / Ph.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (p. 107-110). / by Jose K. Menendez. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012. / "June 2012." Cataloged from PDF version of thesis. / Includes bibliographical references (p. 205-212). / The beginning phases of system development and conceptual design require careful consideration, as these decisions will have significant influence on system lifetime performance and are often made with incomplete system knowledge. Decision makers may improve their capacity to discriminate between system concepts and design choices by measuring a system's "ilities" such as changeability, evolvability, and survivability. These ilities may enable systems to respond to perturbations in the design space, context space, and needs space in order to ensure system functionality and adequate performance over time. A system may be designed to change in response to perturbations, or remain statically robust/survivable to perturbations in order to avoid deficiencies or failures. This research attempts to analyze the mechanisms that allow system changes to occur. More specifically, this research will further the characterization of system changeability and evolvability and ultimately provide a structured and meaningful way of classifying system characteristics often described as "ilities". Value sustainment is proposed as an ultimate goal of systems, providing value in spite of perturbations in design, context, or needs. The premise of value sustainment is investigated through four distinct research thrusts: 1) a basis for defining system changes and ilities; 2) a system change examples database with categorical cluster analysis case research; 3) epoch-shift, impact, response, outcome case research; and 4) expert interviews case research. Focusing on change-related ilities, this research proposes constructs for identifying and enabling vague, yet desirable, system properties. Evolvability is characterized as a subset of changeability and defined as the ability of an architecture to be inherited and changed across generations [over time], with a set of ten proposed design principles including decentralization, redundancy, targeted modularity, scalability, integrability, reconfigurability, mimicry, leverage ancestry, disruptive architectural overhaul, and resourceful exaptation. / by Jay Clark Beesemyer, Jr. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011. / Cataloged from PDF version of thesis. Vita. / Includes bibliographical references (p. 52-55). / Neck and back pain is one of the most common musculoskeletal complaints in personnel in variable acceleration environments such as astronauts and military pilots. Ultrasound is known for dynamic imaging and diagnostic workup of the axial and appendicular skeleton, but is not currently used to image the cervical spine, the injury of which may change the biomechanics of the cervical vertebrae, which CT and MRI (the current gold standard in cervical spine imaging) are poor at capturing. To validate ultrasound as a modality for imaging dynamic motion of the cervical spine several experiments were performed in static and dynamic human and animal (ovine) models: 1. Static analysis of ex-vivo ovine cervical spines imaged by ultrasound, MRI, and CT demonstrated that the imaging modality affected the measured intervertebral disc height (p<0.01); similar evaluation was done in-vivo in Emergency Department patients who received a CT scan as part of their clinical course that showed that ultrasound could fit into existing clinical workflows. 2. Dynamic analysis of isolated ex-vivo ovine cervical spinal segments intervertebral disc displacement with a mounted ultrasound probe demonstrated a measurement uncertainty of ± 0.2 mm and no bias at low frequency sinusoidal spinal displacement. A similar evaluation in-vivo with humans with an ultrasound probe mounted on a cervical-collar found a 0.8-1.3 mm amount of cervical spine distraction from the C4-5 Functional Spinal Unit. In human cadavers subjected to passive flexion and extension of the cervical spine, ultrasound measurements of the relative flexion/extension angles between consecutive cervical vertebrae were similar to fluoroscopy. 3. Ultrasound was able to record dynamic motion of the cervical spine in-vivo in running on a treadmill, during parabolic flight, and traveling over a rough road in a military vehicle. The ultrasound methods developed and tested in this thesis could provide an inexpensive, portable and safe technique that can identify and characterize cervical spine anatomy and pathology. / Funding Acknowledgment: National Space Biomedical Research Institute, Army Research Office, Children's Hospital Orthopedic Surgery Foundation / by Daniel Miller Buckland. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000. / Includes bibliographical references (p. 253-255). / The development of high aspect-ratio, high precision micromachining in silicon or silicon carbide suggests the feasibility of rnicrofabricated, high chamber pressure chemical rocket engines. Such an engine, approximately 20x15x3 mm in size, would produce about three pounds of thrust using 300 sec I sp propellants. As part of the present work, the feasibility of these engines has been investigated and a liquid-cooled, pressure-fed thrust chamber has been designed, fabricated, and tested to evaluate the feasibility of the concept. The results of the tests to date using oxygen and methane as propellants support the feasibility of the concept, producing a maximum thrust of 1 N at a chamber pressure of 12 atm. Given the 1.2 gram mass of the thrust chamber, this corresponds to a thrust-to-weight ratio of 85:1. The characteristic exhaust velocity, c*, a measure of combustion effectiveness, appears to be nearly independent of chamber pressure, indicating that chemical reaction rates are not limiting the combustion. Additionally, when effects of chamber heat loss are included, c* appears to approach its predicted ideal value, indicating that the transport and mixing of propellants in the combustion chamber is of the right order to provide for complete combustion. The thrust chamber was fabricated by etching the required patterns into each side of six 0.5 mm thick silicon wafers, and then diffusion bonding the six wafers together to create the one-piece thrust chamber. A packaging technique is presented to interface high pressure and high temperature fluids to the silicon rocket engine chip. Additionally, initial modelling work has lead to the development of a methodology for mapping the feasible design space of microrocket engines, and for optimizing the performance of such systems given current limitations in microfabrication technology. / by Adam Pollok London. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004. / Includes bibliographical references (p. 85). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / The theoretical and numerical evaluation of synergistic diffusing heat-exchanger design is presented. Motivation for this development is based on current diffuser and heat-exchange technologies in cogeneration plants, which require a large geometric footprint to generate steam using gas-turbine exhaust. A compact design is hypothesized to replace these technologies using synergistic design concepts. An investigation into the feasibility of such design concepts are conducted, providing pressure-recovery, viscous losses and thermal energy extraction sensitivities to cooling and annular blade geometry variations. Results show promising diffusion and heat-transfer capabilities that match or surpass current design performance. Proposed configurations are outlined based on these results that compare favorably to a baseline industrial cogeneration application. / by David S. Lazzara. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008. / Includes bibliographical references (p. 161-164). / Measured differences between human and primate VOR may derive from disparate experiences with psychophysical motion stimuli. To test this hypothesis, horizontal and torsional eye movements, as well as roll tilt perception, were measured in both "naive" and "experienced" human subjects during 0.5 Hz sinusoidal roll motion. Between these measurement sessions, subjects experienced pseudo-random roll tilt adaptation sessions. For half of the subjects, these adaptation sessions occurred in the light. Subjects participated in 12 measurement sessions and 9 adaptation sessions over the course of three days. (1) The presence of visual cues did not significantly affect horizontal or torsional VOR, but did adversely influence perception of roll tilt as measured using a somatosensory bar. (2) Torsional VOR followed a pattern of habituation and/or adaptation for naive and dark-adapted subjects. (3) Experienced subjects made horizontal eye movements of significantly larger amplitude than those made by naive subjects. (4) The motion paradigm yielded a significant decrease in torsional amplitude without a corresponding decrease in horizontal amplitude. These last two findings suggest experience does not affect the horizontal VOR. Consequently, the hypothesis that human/primate horizontal VOR differences stem from dissimilar motion experience is not supported. Primate and human VOR must continue to be studied separately. / by Robert P. Ocampo. / S.M.