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Aeronautics and Astronautics - Ph.D. / Sc.D.

Mostrando recursos 1 - 20 de 709

  1. Statistical modeling of aircraft engine fuel burn

    Chati, Yashovardhan Sushil
    Fuel burn is a key driver of aircraft performance, and contributes to airline costs and aviation emissions. While the trajectory (ground track) of a flight can be observed using surveillance systems, its fuel consumption is generally not disseminated by the operating airline. Emissions inventories and benefits assessment tools therefore need models that can predict the fuel flow rate profile and fuel burn of a flight, given its trajectory data. Most existing fuel burn estimation tools rely on an architecture that is centered around the Base of Aircraft Data (BADA), an aircraft performance model developed by EUROCONTROL. Operational data (including trajectory...

  2. Network navigation with scheduling

    Wang, Tianheng, Ph. D. Massachusetts Institute of Technology
    Network navigation is a promising paradigm for enabling location-awareness in dynamic wireless networks. A wireless navigation network consists of agents (mobile with unknown locations) and anchors (possibly mobile with known locations). An agent can estimate its locations based on inter- and intra-node measurements, as well as prior knowledge. In the presence of limited wireless resources, only a subset rather than all of the node pairs can perform inter-node measurements at a time. The procedure of selecting node pairs at different time instants for inter-node measurements, referred to as network scheduling, affects the time evolution of agents' localization errors. The key...

  3. The causes and consequences of divergence between the air traffic controller state awareness and actual system state

    Abel, Brandon R. (Brandon Ross)
    Divergence is an inconsistency between the human's system state awareness and the actual system state. This research investigated divergence potential in air traffic controllers and identified controller divergence causes and consequences. Based on this investigation, approaches to minimize controller divergence and its consequences were identified for current air traffic control systems and future systems where unmanned aircraft will be integrated. Prior studies identified pilot divergence as a factor in several recent aircraft accidents and could be a factor for controllers. The future addition of unmanned aircraft in national airspace is a significant change which will affect the pilot and controller...

  4. Generative multi-robot task and motion planning over long horizons

    Fernández González, Enrique, Ph. D. Massachusetts Institute of Technology
    The state of the art practice in robotics planning is to script behaviors manually, where each behavior is typically precomputed in advance. However, in order for robots to be able to act robustly and adapt to novel situations, they need to be able to plan sequences of behaviors and activities autonomously. Since the conditions and effects of these behaviors are tightly coupled through time, state and control variables, many problems require that the tasks of activity planning and trajectory optimization are considered together. There are two key issues underlying effective hybrid activity and trajectory planning: the sufficiently accurate modeling of...

  5. Data-driven methods for statistical verification of uncertain nonlinear systems

    Quindlen, John Francis
    Due to the increasing complexity of autonomous, adaptive, and nonlinear systems, engineers commonly rely upon statistical techniques to verify that the closed-loop system satisfies specified performance requirements at all possible operating conditions. However, these techniques require a large number of simulations or experiments to exhaustively search the set of possible parametric uncertainties for conditions that lead to failure. This work focuses on resource-constrained applications, such as preliminary control system design or experimental testing, which cannot rely upon exhaustive search to analyze the robustness of the closed-loop system to those requirements. This thesis develops novel statistical verification frameworks that combine data-driven...

  6. Motion cues in man-vehicle control.

    Shirley, Richard S
    Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics. Thesis. 1968. Sc.D.

  7. Guidance parameters and constraints for controlled atmospheric entry

    Duncan, Robert C. (Robert Clifton)
    by Robert C. Duncan.

  8. Pointing system performance analysis for optical inter-satellite communication on CubeSats

    Yoon, Hyosang
    Free-space optical communication using lasers (lasercom) is a leading contender for future space-based communication systems with potential advantages over radio frequency (RF) communication systems in size, weight, and power consumption (SWaP). Key benefits are due to the shorter wavelength: additional bandwidth and narrow beam width. The narrower beam supports higher energy density for a given aperture size, so that lasercom can transmit data at the same rate with smaller SWaP as well as improve link security since the beam footprint is smaller. Lasercom is an attractive option for improving inter-satellite links (ISL) for resource-constrained CubeSats, which have emerged as a...

  9. Optimal control for wireless networks

    Sinha, Abhishek, Ph. D. Massachusetts Institute of Technology
    One of the most fundamental problems in Computer Networking is to efficiently route packets belonging to different sessions, such as unicast, broadcast, multicast and anycast, collectively known as the generalized flows. The goal of this thesis is to design an efficient routing, and wireless link scheduling policy, that maximizes net throughput. Currently, the only known throughput-optimal policy is the Backpressure policy for the unicast problem. In this thesis, we propose provably optimal algorithms for the broadcast and the generalized flow problems. Our study begins with the problem of optimal broadcasting in a wireless Directed Acyclic Graph (DAG). Existing policies achieve...

  10. Design as a search problem : interactive visualization for system design under uncertainty

    Curry, Michael Dale
    Epoch Era Analysis (EEA) was developed to better model problems with lifecycle uncertainties and has demonstrated its usefulness in prior research studies, but it still faces significant challenges to practical application. Specifically, EEA can result in large, multivariate datasets that are difficult to generate, visualize and perform analysis on. When performing exploratory analysis on such model-generated data sets, human interaction is often necessary to identify important subsets of the data, resolve ambiguity or find inconsistencies. Although prior research towards methods for applying EEA constructs has been performed, a prescriptive framework that explicitly considers human interaction does not exist. To make...

  11. Angles-only navigation technique for maneuver-free spacecraft proximity operations

    Yates, Max William, Major
    The technique of angles-only navigation consists of a single surveyor making line-of-sight observations of a target to deduce a relative navigation state from a sequence of angle measurements. Historically, angles-only navigation has been impeded by a range ambiguity problem in its many applications, especially those involving linear dynamical models. A classical solution to the problem is for the surveyor to perform precise maneuvers to change the nominal angle profile between the surveyor and the target. In the space environment, the orbital dynamics are inherently nonlinear and natural orbit perturbations have the effect of continuous micro-maneuvers. These advantageous conditions present an...

  12. On the low-dimensional structure of Bayesian inference

    Spantini, Alessio
    The Bayesian approach to inference characterizes model parameters and predictions through the exploration of their posterior distributions, i.e., their distributions conditioned on available data. The Bayesian paradigm provides a flexible, principled framework for quantifying uncertainty, wherein heterogeneous and incomplete sources of information (e.g., prior knowledge, noisy observations, imperfect models) can be properly rationalized. Yet a major obstacle to deploying Bayesian inference in realistic applications is computational: characterizing the associated high-dimensional and non-Gaussian posterior distributions remains a challenging task. While the Bayesian formulation is quite general, essential features of a statistical model can bring additional structure to the Bayesian update. For...

  13. Simulation methods for plasmonic structures

    Vidal-Codina, Ferran
    In the recent years there has been a growing interest in studying electromagnetic wave propagation at the nanoscale. The interaction of light with metallic nanostructures produces a collective excitation of conduction electrons at the metal surface, also known as surface plasmons. These plasmonic resonances enable an unprecedented control of light by confining the electromagnetic field to regions well beyond the diffraction limit, thereby leading to nearfield enhancements of the incident wave of several orders of magnitude. These remarkable properties have motivated the application of plasmonic devices in sensing, nano-resolution imaging, energy harvesting, nanoscale electronics and cancer treatment. Despite state-of-the-art nanofabrication...

  14. Control of stochastically interacting systems on networks

    Somanath, Amith
    The goal of this thesis is to develop control theoretic analysis and algorithms for characterizing and controlling stochastically interacting systems on networks. Such systems have three essential features - (i) they are stochastic processes, (ii) they are made up several individual components connected through a network, and (iii) the connected components influence one another through local interactions. This thesis presents analysis and control of three representative examples of such systems from the fields of spreading processes, smart manufacturing, and transport phenomena. In the first part of the thesis, control of spreading processes on lattices is considered. Analysis and control of...

  15. Support of latency-sensitive space exploration applications in future space communication systems

    Sanchez Net, Marc
    Latency, understood as the total time it takes for data acquired by a remote platform (e.g. satellite, rover, astronaut) to be delivered to the final user in an actionable format, is a primary requirement for several near Earth and deep space exploration activities. Some applications such as real-time voice and videoconferencing can only be satisfied by providing continuous communications links to the remote platform and enforcing hard latency requirements on the system. In contrast, other space exploration applications set latency requirements because their data's scientific value is dependent on the timeliness with which it is delivered to the final user....

  16. Autonomous navigation in unknown environments using machine learning

    Richter, Charles Andrew
    In this thesis, we explore the problem of high-speed autonomous navigation for a dynamic mobile robot in unknown environments. Our objective is to navigate from start to goal in minimum time, given no prior knowledge of the map, nor any explicit knowledge of the environment distribution. Faced with this challenge, most practical receding-horizon navigation methods simply restrict their action choices to the known portions of the map, and ignore the effects that future observations will have on their map knowledge, sacrificing performance as a result. In this thesis, we overcome these limitations by efficiently extending the robot's reasoning into unknown...

  17. System modeling, design, and control of the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) and implications for atmospheric ISRU processing plants

    Meyen, Forrest Edward
    As humankind expands its footprint in the solar system, it is increasingly important to make use of Earth independent resources to make these missions sustainable and economically feasible. In-Situ Resource Utilization (ISRU), the science of using space resources to support exploration missions, unlocks potential destinations by significantly reducing the mass to be launched from Earth. Mars is considered a promising location with significant indigenous resources. The carbon dioxide that comprises nearly 96% of the Martian atmosphere can be utilized to produce oxygen for propulsion and life support systems. The Mars Oxygen ISRU Experiment (MOXIE) is a payload being developed by...

  18. A system level study of new wake turbulence separation concepts and their impact on airport capacity

    Kolos-Lakatos, Tamás
    The air transportation industry continues to grow worldwide, but demand is often limited by available airspace and airport capacity. This thesis focuses on evaluating new air traffic procedures: specifically, new and emerging wake turbulence separation rules that could potentially increase runway capacity based on today's knowledge of wake vortex turbulence and technological capabilities. While legacy wake separation rules establish aircraft-classes based on weight of aircraft, these new separation rules can define separation standards by considering other aircraft parameters and dynamic wind conditions. A fast-time runway system model is developed for studying these wake separation rules, using Monte-Carlo simulations, to provide...

  19. Effect of control interface implementation on operation of a multi degree of freedom telerobotic arm

    Hall, Sherrie Alyssa
    In exploration, scenarios can include a human working along-side - or attached to - a robot. For example, concepts of Mars human-robot exploration teams, or extravehicular activity (EVA) on the International Space Station (ISS) with an astronaut fixed to the end of a large robot arm for stability. Robots in these scenarios must be able to be directed in real time to react to environmental unknowns. In this work, use of a fully-wearable gesture system was proposed to provide control of the robot to the human in the field. A wearable gesture interface would allow user mobility in the field,...

  20. Human-machine collaborative optimization via apprenticeship scheduling

    Gombolay, Matthew C. (Matthew Craig)
    I envision a future where intelligent service robots become integral members of human-robot teams in the workplace. Today, service robots are being deployed across a wide range of settings; however, while these robots exhibit basic navigational abilities, they lack the ability to anticipate and adapt to the needs of their human teammates. I believe robots must be capable of autonomously learning from humans how to integrate into a team ' la a human apprentice. Human domain experts and professionals become experts over years of apprenticeship, and this knowledge is not easily codified in the form of a policy. In my...

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