Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Inertial Parameter Identification of a Captured Payload Attached to a Robotic Manipulator on a Free-Flying Spacecraft(2024) Limparis, Nicholas Michael; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The groundwork for the dynamics of a free-flyer with a manipulator has been laid out by Yoshida, Vafa and Dubowsky, and Papadopoulos and Moosovian with the Generalized Jacobian Matrix, Virtual Manipulator, and Barycentric Vector Approach respectively. The identification of parameters for a robot manipulator has also been approached for industrial robots as well as through adaptive control theory. What is proposed is a method for inertial parameter identification and verification for a spacecraft with an attached manipulator that is an extension of the ground-fixed Inverse Direct Dynamic Model to function for a free-flying spacecraft. This method for inertial parameter identification for a spacecraft-manipulator system with an attached client spacecraft, debris, or other grappled payload is developed in this thesis and is experimentally tested using results for a servicer and an "unknown" grappled payload using three separate test beds. The results of the experiments show that the proposed method is capable of identifying the inertial parameters of the servicer and the grappled payload.Item A CASE STUDY OF RED BULL’S USE OF SPORTING EVENTS IN THE NEOLIBERAL URBAN ENVIORNMENT(2024) Weber, Emilio; Andrews, David L.; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This project critically examines the ways in which city space and place are mobilized for capital interests through an examination of the global sports and energy drinks brand, Red Bull, and specifically its urban-based event strategies. The events such as the ones Red Bull hosts, alongside other spectacular urban projects have been prominent endeavors in which the lived experience of space has been reformulated by those who wield power and influence in the city. Informed by the contextual forces and logics of neoliberal urbanism, Red Bull strategically deploys the physical and symbolic reformulation of cities as an important aspect of its brand marketing strategy. The company, alongside local entities, impact the physical environment of the urban areas they occupy for the events. In addition, representations of places are presented and altered. These alterations of urban space and place have included an increased focus on spectacular consumption sites and experiences, in addition to the policing and surveillance of such spaces. Furthermore, this thesis offers analytical insight into the ways Red Bull’s urban strategizing is both and product and producer of the normalized neoliberal fabric that has come to envelope the contemporary US city: ultimately reproducing urban spaces which promote private profit and continue or exacerbate the inequalities felt in cities. Drawing from a range of interdisciplinary scholarship, I examine the relationship between, and impact of, sporting events hosted within the context of neoliberal cities. Deploying theoretical frameworks based in urban studies, neoliberalism, and critical geography informs the literature review and my research. This literature includes, but is not restricted to, physical cultural studies, urban studies, the sociology of sport, and event literature. Additionally, I utilize a case study method to examine the nature of the events within the urban and sport context they take place in. Completing field research and participant observation at three Red Bull sporting events, hosted in three distinct locales in June 2023, August 2023, and February 2024, I focus on the composition, meaning, affect, and experience of urban space, as created by the event itself, alongside marketing and promotional strategies of the company and cities in relation to these events. The research findings are divided into two empirical chapters, focused on the material and symbolic impacts upon urban space and place, respectively. I posit these findings as a normalized occupation of urban space, following the logics of neoliberalism and the event/content production of Red Bull. In conforming to neoliberal capitalist ideas focused on commercialized spectacle, these events simultaneously work to normalize this corporate use of urban space.Item Free Space: Envisioning the Low Earth Orbit Metropolis(2021) Mazer, Andrew Joseph; May, Lindsey; Dawkins, Casey; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This thesis posits a permanent, free space settlement and a space-based regional plan as the first step in sustainable and ethical settlement beyond Earth. The settlement paradigm explores modular and redundant construction and planning techniques that could be scaled and replicated to achieve long-range missions of exploration and long-term space settlement. A systems-based strategy within Low Earth Orbit provides the first architectural steppingstone for humans to realize themselves as a multi-planetary species. Space hosts a plethora of untapped and un-realized resources that have yet to be imagined for the betterment of life on Earth. As a result, it is imperative to plan and to think about what the consequences a permanent settlement in outer space could mean for life on Earth. In exploration, this thesis sets forth a strategy to ensure outer space and its resources are used fairly, responsibly, and justly, and access is promoted equitably, ethically, and morally to all who have a hand in a globally collaborative human agenda.Item A MODEL TO PREDICT THE SIZE OF 3D REGOLITH CLUMPS ON PLANETARY BODIES(2020) Patel, Anand Vijaykumar; Hartzell, Christine M; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Prior investigations of the behavior of regolith on the surface of planetary bodies has considered the motion and interactions of individual grains. Recent work has shown the significance of cohesion in understanding the behavior of planetary regolith, especially on small, airless bodies. Surficial regolith grains may detach from a planetary body due to a variety of phenomena, including aeolian effects, spacecraft operations, micrometeoroid bombardment and electrostatic lofting. It is well known in terrestrial powder handling that cohesive powders tend to form clumps. We present an analytical theory for the size of regolith clumps that are likely to form and be easier to detach from a surface than their constituent grains, assuming monodisperse, spherical grains. The model predictions are significant for our interpretation of the surface of asteroids, as well as understanding a variety of phenomena on planetary bodies and designing of sampling spacecraft.Item An experimental and graph theoretic study of atomic layer deposition processes for spacecraft applications(2019) Salami, Hossein; Adomaitis, Raymond A; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Accurate understanding of the atomic layer deposition (ALD) process kinetics is necessary for developing new ALD chemistries to produce novel nanomaterials, and also optimization of typical ALD processes used in industrial applications. Proposing a potential reaction sequence alongside with accurate kinetic data is among the very first steps in studying the ALD process kinetics and forms the backbone of further engineering analysis. A valid and proper ALD reaction net work (RN) must be able to reflect the self-limiting and cycle to cycle reproducibility behavior experimentally observed for practical ALD processes. Otherwise, the mathematical model built based on it fails to precisely capture and reproduce ALD behavior no matter how accurate the available kinetic data are. In this work, a RN analysis method based on species-reaction graphs and the principles of convex analysis is developed to study the mathematical structure and dynamical behavior of thin-film deposition RN models. The key factor in ALD RN analysis is the presence of consistent surface-originated invariant states for each ALD half-cycle. Therefore, the primary focus of the proposed approach is on identifying and formulating physically-relevant RN invariant states, and to study the chemical significance of these conserved modes for ALD reaction mechanisms. The proposed method provides a well-defined framework, applicable to all ALD systems, to examine the above criteria of a proper ALD RN without requiring any information on the reaction rates. This method fills a gap in the procedure of ALD process modeling before the time-consuming step of calculating individual reaction rates which is usually done through ALD experiments in reactors equipped with in-situ measurement instruments or computationally expensive computational chemistry-based calculations such as density functional theory. The presented approach is also extended to study the variant states of a RN. The generalized method provides information on different variant states dynamically depending on each individual reaction in the network which facilitates the study and ultimately the formulation of different reaction rates in the system. In the second part of this dissertation, an experimental study of ALD of indium oxide and indium tin oxide films using the trimethylindium, tetrakis (dimethylamino) tin(IV), and ozone precursor system is conducted to first, investigate the potential application of this ALD process for producing high-quality transparent conducting layers; and second, to understand the relationship between the thickness of the deposited films and their electrical and optical properties. The optimized recipe was then used to process commercial Z93 heat radiator pigments used in manufacturing spacecraft thermal radiator panels to enhance their electrical conductivity to avoid the differential charging that may occur due to the interaction with charged particles in Van Allen radiation belts. To this aim a specialized ALD reactor was designed and constructed capable of processing standard flat substrates as well as coating micron-sized particles. The results confirm that the proposed process can be used to coat the heat radiator pigment particles and that the indium oxide film can nucleate and grow on their surface. This provides an example from a variety of potential space-related applications that can benefit from the ALD process.Item Morphing Waveriders for Atmospheric Entry(2019) Maxwell, Jesse R; Oran, Elaine S; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The primary challenge for vehicles entering planetary atmospheres is surviving the intense heating and deceleration encountered during the entry process. Entry capsules use sacrificial ablative heat shields and sustain several g deceleration. The high lift produced by the Space Shuttle geometry resulted in lower rates of heating and deceleration. This enabled a fully reusable vehicle that was protected by heat shield tiles. Hypersonic waveriders are vehicles that conform to the shape of the shock wave created by the vehicle. This produces high compression-lift and low drag, but only around a design Mach number. Atmospheric entry can reach speeds from zero to as high as Mach 40. A morphing waverider is a vehicle that deflects its flexible bottom surface as a function of Mach number in order to preserve a desired shock wave shape. It was demonstrated in this work that doing so retains high aerodynamic lift and lift-to-drag ratio across a wide range of Mach number. Numerical simulations were conducted for case-study waveriders designed for Mach 6 and 8 for flight at their design conditions as well as with variations in angle-of-attack and Mach number. A single-species air model was used between Mach 1 and 12 with the RANS k-omega SST and LES-WALE turbulence models. A seven-species air model was used for Mach 15 at 60km altitude and Mach 20 at 75km. Analytical methods were used to construct a reduced-order model (ROM) for estimating waverider aerodynamic forces, moments, and heating. The ROM matched numerical simulation results within 5-10% for morphing waveriders with variations in angle-of-attack, but discrepancies exceeded 20% for large deviations of rigid vehicles from their design Mach numbers. Atmospheric entry trajectory simulations were conducted using reduced-order models for morphing waverider aerodynamics, the Mars Science Laboratory (MSL) capsule, and the Space Shuttle. Three morphing waveriders were compared to the Space Shuttle, which resulted in reduced heating and peak deceleration. One morphing waverider was compared to the MSL capsule, which demonstrated a reduction in the peak stagnation heat flux, a reduction in the peak and average deceleration, and a reduction in the peak area-averaged heating.Item MECHANICAL DESIGN OF DEXTEROUS MANIPULATOR LINKS(2018) Carlsen, Christopher James; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper explores the challenges of dense structure-electronics packaging, specifically for a structural and electronics upgrade to the Ranger Tele-robotic Shuttle Experiment (RTSX) manipulators at the University of Maryland (UMD). Long serial-link manipulators are popular in the space industry, where the need for a long reach and high manipulability outweighs the need for high tip stiffness. For larger systems with co-located electronics, such as those used to berth vehicles on orbit, electronics packaging is not inhibited by the diameter of the link body. As link diameter decreases, co-locating electronics in the manipulator becomes diffcult without adding external extensions to house them. In such densely packed bodies, the control electronics are so integrated with structure that electronics maintenance requires disassembly of primary structure.Item TASK-BASED OPTIMIZATION OF MULTI-ARM SPACE ROBOTICS(2018) McBryan, Katherine Marie; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)There are many benefits to using multi-arm systems over a single arm system including higher flexibility in planning, better payload handling capacity, and reduction of joint torques. However, multi-arm systems are inherently more complex. This complexity does not necessarily translate to ``bigger" and ``heavier". This research seeks to answer the question of whether or not a multi-arm system can have lower mass than a single arm system. Using a task-based methodology, Independent single-arm and cooperative dual-arm manipulator systems are designed. A task defines the payload's motion and thus the manipulator's trajectory. Utilizing linear programming, a new method is developed in order to optimize the distribution of forces among the multiple arms in order to guarantee a minimum system mass. The mass of the motors and gears are estimated based on the required torque and speed, obtained from the trajectory and force-distribution. This study shows that a well-designed multi-arm system can in fact have a lower mass than a single-arm system. Further optimization demonstrates that a multi-arm system, when designed as a complete system rather than individual parts, can significantly reduce the total system mass.