Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006. / Includes bibliographical references (p. 117-123). / Cognitive projection enables the operator of a supervisory control system, such as air traffic control, to use predicted future behavior of the system to make decisions about if and how to control the system. New procedures and technologies being implemented in the air traffic control system innately affect the information used for projection and the type of projection required from the controller. Because cognitive projection is not well-understood, launching these projection-impacting technologies and procedures could result in the reluctance of the air traffic controllers to accept these advancements or limit the system performance. A Projection Process Model and a Projection Error Concept were proposed to describe the controller's projection process and the contextual system influences on the projection process. The two primary influences on the projection process were information/display system and task-based projection requirements. A mismatch between the information/display system states and the task-based projection requirements was described through a cognitive transform concept. The projection process itself is composed of the state mental model and the time into the future over which the projection is made. / (cont.) Hypotheses based on the assumptions of the Projection Process Model and Projection Error Concept were probed through an experiment using an ATC task paradigm. Results were consistent with the proposed models. They suggested that the controllers were able to incorporate higher-level dynamics into the state mental models used for projection and that the quality of the state mental model used was marginally influenced by the error tolerance required in the task. The application of the Projection Process Model and Projection Error Concept was then illustrated through the analysis of the impact on projection from two ATC domain examples of technology and procedure implementation. The Constant Descent Approach Procedure in the TRACON impacted the intent, projection timespan, and abstractions used in the mental model of the controllers. The Oceanic ATC surveillance, communication and workstation improvements resulted in an impact on the states to be projected, intent, projection timespan, and human/automation projection responsibility. Suggestions for improved transition for the projection process were then provided based on the analysis. / by Hayley J. Davison Reynolds. / Ph.D.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 131-133). / The quest for increased resolution pushes telescope designs toward larger and larger apertures. This has motivated the development and expansion of distributed-aperture imaging. In radio wavelengths, distributed aperture signals can be recorded separately and correlated in software, but optical and infrared interferometry cannot currently use this approach because absolute phase must be captured. Instead, the beams from each sub-telescope must be brought together and interfered pairwise in order to measure relative phases and coherences, or "visibilities," by observing interference fringes. As the number of apertures increases, the number of pairs increases quadratically and pairwise fringe measurement becomes impractical. Direct-imaging interferometers instead combine all beams simultaneously by imaging the outputs onto a detector. Each aperture pair contributes a spatial frequency to the output, and the result is an image of the source instead of pairwise visibility information The densified-pupil direct-imaging interferometer, or hypertelescope, is a promising concept for future high-resolution imaging, both in space and on the ground; it offers the sharp resolution and efficient beam-combination of similar interferometric methods, but increases power in the PSF core through pupil densification. When implemented with single-mode fibers, the hypertelescope offers simplicity and the ability to expand to many-aperture configurations. However, broadband imaging requires that the optical path lengths all be matched to within a fraction of the wavelength. Telescopes of this type have been demonstrated, but generally rely on manual tuning of delay lines and air gaps in order to match the optical path lengths. This is not practically extensible to many-aperture configurations with hundreds or thousands of baselines, and is also difficult to implement in space, where a more automated procedure is required. Many methods for interferometer fiber length measurement have been developed, but most rely on extensive internal metrology or a specific calibration source, such as a polarized laser reference. Starting from the known concept of visibility phase sampling from the frequency-domain representation of a direct image, this work develops and characterizes a set of algorithms for the calibration of absolute path lengths in many-aperture fiber-linked hypertelescopes using only mis-calibrated images taken at a few wavelengths, enabling path-matched broadband imaging at high resolution. The unique baselines, fiber spatial filtering, and densified-pupil architecture of these telescopes enables these methods to be particularly effective, and a many-aperture configuration supports the inference of missing quantities of from the statistical properties of the apertures. An optimized frequency-sampling method extracts baseline phases from the miscalibrated image of a known source, and an efficient method for solving for aperture phases is presented. Observing and solving for the aperture phases at multiple wavelengths extends phase information into path length information using an expanded robust Chinese Remainder Theorem algorithm, and then the absolute offset and telescope pointing errors can be inferred from the statistics of the aperture path length errors. A simulation framework for fiber-linked densified-pupil direct-imaging interferometers is developed in order to test these algorithms and characterize the performance. A Fourier-domain signal-to-noise metric is derived, and ideal performance models for these algorithms are presented. The limits of performance are shown to be well-predicted by this metric and known properties of the telescope configuration. Finally, the simulation is used to characterize the effects of finite bandwidths, extended sources, optical aberrations, and pointing errors on the performance and robustness of these algorithms. Path lengths are shown to be measurable, inside a range determined by the calibration wavelengths, to within the required A/10 even in the presence of these non-idealities. / by Riley McCrea Fitzgerald. / S.M.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1988. / Includes bibliographical references. / by John Rawson Spofford. / Sc.D.

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO / Bibliography: leaves [161]-[168]. / by David Gordon Stuart. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (p. 85-86). / by Benjamin E. Torres. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (p. [95]-97). / submitted by Imran Haq. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012. / Cataloged from department-submitted PDF version of thesis. This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 95-98). / Perception is a crucial aspect of the operation of autonomous vehicles. With a multitude of different sources of sensor data, it becomes important to have algorithms which can process the available information quickly and provide a timely solution. Also, an inherently continuous world is sensed by robot sensors and converted into discrete packets of information. Algorithms that can take advantage of this setup, i.e., which have a sound founding in continuous time formulations but which can effectively discretize the available information in an incremental manner according to different requirements can potentially outperform conventional perception frameworks. Inspired from recent results in motion planning algorithms, this thesis aims to address these two aspects of the problem of robot perception, through novel incremental and anytime algorithms. The first part of the thesis deals with algorithms for different estimation problems, such as filtering, smoothing, and trajectory decoding. They share the basic idea that a general continuous-time system can be approximated by a sequence of discrete Markov chains that converge in a suitable sense to the original continuous time stochastic system. This discretization is obtained through intuitive rules motivated by physics and is very easy to implement in practice. Incremental algorithms for the above problems can then be formulated on these discrete systems whose solutions converge to the solution of the original problem. A similar construction is used to explore control of partially observable processes in the latter part of the thesis. A general continuous time control problem in this case is approximates by a sequence of discrete partially observable Markov decision processes (POMDPs), in such a way that the trajectories of the POMDPs -- i.e., the trajectories of beliefs -- converge to the trajectories of the original continuous problem. Modern point-based solvers are used to approximate control policies for each of these discrete problems and it is shown that these control policies converge to the optimal control policy of the original problem in an appropriate space. This approach is promising because instead of solving a large POMDP problem from scratch, which is PSPACE-hard, approximate solutions of smaller problems can be used to guide the search for the optimal control policy. / by Pratik Chaudhari. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2012. / Cataloged from department-submitted PDF version of thesis. This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 91-93). / General aviation (GA) is an important component of aviation in the United States. In 2011, general aviation and air taxi operations represented 63% of all towered operations in the United States, while commercial aviation was responsible for 34% of those operations. It is clear that GA is a considerable component of the national airspace and airport system, even when only accounting for towered operations. Because of this significant presence, insight into GA is relevant to issues in air traffic management, air transportation infrastructure, and aviation safety, among others. Beyond the operational aspect, GA is of significance to society as a whole and to other stakeholders, including pilots groups, aircraft manufacturers, and the work force. In 2009, general aviation generated 496,000 jobs and its total economic contribution to the U.S. economy was valued at $76.5 billion. However, a comparison of general aviation's impact on jobs and on the economy between 2008 and 2009, shows a 20% decrease in jobs and a 21% decrease in total economic impact in the course of a year. There is also a significant decreasing trend in the active pilot population, along with steady decreases in GA flight hours and towered operations. The objective of this thesis is to explore the details of these changing trends and to determine what drives and what hinders general aviation activity in the country. A combination of data analysis and the development of a survey administered to general aviation pilots shed light on what has driven activity in the past on a national scale, what factors affect an individual pilot's level of activity, and what challenges the general aviation community faces in the future. / by Kamala Irene Shetty. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002. / Includes bibliographical references (p. 145). / by Troy D. Downen. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 243-250). / Electrosprays of the pure-ion variety embody a unique collection of attributes that have compelled interest in derivative technologies across a spectrum of applications ranging from Focused Ion Beams (FIB) to microrocketry. Unlike conventional colloid sources (i.e., so-called cone-jets or others sources from which droplets typically emanate), pure ion sprays are commonly characterized by narrow distributions of high specific charge and nominal energy deficits as a result of their evaporative mechanisms. Among other properties of the spray, these are known to enable well-behaved optics (e.g. for nanometric patterning with FIB) and low power overhead (e.g. for efficient electrical-to-kinetic energy transduction in microrocketry) while also providing for innate simplicity and spatial compactness. In spite of their potential for paradigm-shifting impact, the practicality of contemporary pure-ion sources has been tempered by issues relating to reliability and predictability. In contrast to droplet emission, for example, empirical studies strongly suggest that pure-ion modes are only permissible under special sets of circumstances and that important beam qualities (namely the stability but also the current) are sensitive functions of the meniscus configuration. The difficulty in controlling these modes is somewhat abated through the use of fluids like ionic liquids (IL), particularly in connection with several heuristics that have emerged, but the process remains substantially fickle. This is believed to owe most directly to an undeveloped physical understanding. While the physics that govern conventional colloid sources are at least functionally understood at this point, an analogous grasp of their ion relatives has proven elusive. The purpose of this thesis is to begin addressing this issue by way of rigorous theoretical investigations, with the ultimate aim of offering deeper fundamental insight and additional recourse to future design initiatives beyond the existing set of over-simplified heuristics. In this thesis we first conduct a survey of potential contributors to the very multi-physical phenomenon of charge evaporation and identify key influences through basic order-of-magnitude analyses. These are used to inform the formulation of a detailed mathematical framework that is subsequently leveraged in the exploration of evaporation behaviors for a prototypical ionic liquid meniscus across a range of field, media, and hydraulic conditions. The results uncover a previously uncharted family of highly-stressed but ostensibly stable solutions for the problem of a volumetrically-unconstrained source. These appear to be confined to a particular subregion of the global parameter space that emphasizes thoughtful sizing of the meniscus and architecting of the feeding system. The impedance aspect of the latter, in particular, is believed to play a critical role in steady emission when large scale disparities, which are common in practical settings, exist across the parent meniscus. Additional influences that are often neglected in the literature, such as that of the liquid permittivity, are also elucidated and shown to play meaningful roles in evaporation. We conclude by outlining a reasonably comprehensive set of conditions that should be met for steady emission and substantiate these with tangible evidence from our studies. / by Chase Coffman. / Ph. D.