Aerospace Engineering Commons^™

Electrical Characterization Of Germanium Tin Alloys And Devices For Space Reliability, Kevin K. Choe

Theses and Dissertations

GeSn (germanium tin) alloys are potentially well suited for near-mid infrared space optoelectronic applications. Alloys of GeSn have similar properties to group III-V and mercury-cadmium-telluride semiconductors and are compatible with cost-effective complementary metal oxide semiconductor (CMOS) manufacturing technology. Recent progress in non-equilibrium remote plasma-enhanced chemical vapor deposition (RPECVD) has enabled the crystalline growth of GeSn with Sn concentrations of up to 10% without Sn surface segregation. Several experimental studies in previous literature report CVD- or molecular beam epitaxy (MBE)-grown GeSn alloys achieving a direct bandgap with 6%-9% Sn content. This novel growth technique opens opportunities for a cost-effective, next-generation optical …

Tensile Creep Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Waleed S. Alshehri

Theses and Dissertations

Advanced aerospace systems require structural materials that can perform reliably in high-temperature environments for long durations. The performance of standard polymer matrix composites (PMCs) in these conditions is often limited by their susceptibility to time-dependent deformation, such as creep. The objective of this research is to characterize the high-temperature creep behavior of a novel unitized material system comprising a polymer matrix composite (PMC) and a ceramic matrix composite (CMC) co-cured together. The PMC part consists of the polyimide matrix reinforced with laminated carbon fibers woven in an eight harness satin weave (8HSW). The CMC part consists of a zirconia-based ceramic …

Low-Cost Transfers For Cislunar Liaison Navigation, Ka'eo J. Swartzmiller

Theses and Dissertations

CubeSats have an inherent limitation on volume due to their small form factor. Naturally, this extends to the capacity of on-board ΔV, thus limiting the maneuverability of the satellites. This limited maneuverability makes it extremely important to be intentional when planning out mission trajectories. The cislunar region subjects these trajectories to the gravitational forces of both the Earth and the Moon, making it all the more necessary to deliberately plan out maneuvers. The Circular Restricted Three Body Problem (CR3BP) provides a simpler model for estimating the motion of spacecraft within the cislunar region, allowing for the gravitational forces to be …

Multi-Fidelity Machine Learning Modeling For Aerodynamic Response Prediction Of Aerospace Vehicles, Ethan S. Jackman

Theses and Dissertations

Hypersonic vehicle design requires understanding complex aerodynamic phenomena across the full flight regime. This study presents a novel MF surrogate modeling methodology that enables the prediction the full field response across a vehicle’s surface. A Space-Filling Curve (SFC) is used to convert unstructured data into 1D vectors. The a Convolutional Autoencoder is used with transfer learning to reduce the dimensionality of the data. An Emulator-Embedded Neural Network (E2NN) combines multi-fidelity data for fast, accurate predictions. A benchmark analytical example and hypersonic application are used to evaluate the methodology. Using various numbers of samples and sampling strategies it is found that …

Sparse-Data Orbit Estimation In Low Earth Orbit Using The Markov Chain Monte Carlo Ensemble Gaussian Mixture Filter, Nicholas J. Oden

Master's Theses

The number of space objects (SOs) in low Earth orbit (LEO) continues to increase rapidly, creating challenges for the current ground-based tracking network, which cannot accommodate the projected growth in SOs. Catalog maintenance relies on frequent observations for reliable reacquisition, with Two-Line Element (TLE) sets typically generated daily to mitigate rapid error growth from poor TLE accuracy. This constraint limits the ability to track more objects with existing infrastructure. This work evaluates the Markov Chain Monte Carlo Ensemble Gaussian Mixture Filter (MCMC EnGMF), a nonlinear, non-Gaussian filter well-suited for sparse tracking scenarios where higher post-update accuracy is needed to reduce …

Reduced Order Models Of Hydrodynamically Interacting Flapping Wings, Jose Pabon

Dissertations

Fish schools exhibit a collective behavior and self-organization that is mediated by hydrodynamic interactions between individual fish. However, the long-time evolution of hydrodynamically interacting collectives is challenging to investigate due to the persistent influence of long-lived vortical structures, and the high-resolution requirements of direct numerical simulation at large Reynolds numbers. Reduced-order models have therefore played an important role in theoretical investigations of collectives of swimming bodies. The main results detailed herein are several new reduced-order models of swimmers that self-propel by flapping, i.e., by executing a prescribed periodic rigid body motion. The models are extensions of a discrete-time dynamical system …

Lifting-Line Predictions For Optimal Dihedral Distributions In Ground Effect, Amanda K. Olsen, Zachary S. Montgomery, Douglas F. Hunsaker

Mechanical and Aerospace Engineering Student Publications and Presentations

When a flying wing comes within close proximity to the ground, a phenomenon called ground effect occurs where the lift is increased and the induced drag is decreased. This research seeks to determine the optimal dihedral distribution predicted by lifting-line theory that minimizes induced drag in ground effect. Despite some limitations, using lifting-line theory for this study allows for quick results across a large range of design variables, which would be infeasible for high-fidelity methods. The SLSQP optimization method is used along with a numerical lifting-line code to find the dihedral distribution that minimizes induced drag. Results are presented showing …

Grain Size- And Temperature-Dependent Phonon-Mediated Heat Transport In The Solid Electrolyte Interphase: A First-Principles Study, Arjun S. Kulathuvayal, Yanqing Su

Mechanical and Aerospace Engineering Student Publications and Presentations

The solid electrolyte interphase (SEI) is a passive layer, typically a few hundred angstroms thick, that forms on the electrode surface in the first few battery cycles when the electrode is in contact with the electrolyte in lithium-metal batteries. Composed of a combination of lithium salts and organic compounds, the SEI plays a critical role in battery performance, serving as a channel for Li-ion shuttling. Its structure typically comprises an inorganic component-rich sublayer near the electrode and an outer organic component-rich sublayer. Understanding heat transport through the SEI is crucial for improving battery pack safety, particularly since the Li-ion diffusion …

Contributing Factors To Low Airspeed On Climb-Out As A Precursor To Loss Of Control In Flight, Owen D. Poborsky

Journal of Aviation Technology and Engineering

The nature of aviation is not without inherent risk. Conducting training flight operations increases these inherent risks. Flight data monitoring and voluntary safety action programs seek to reduce risk, as seen in their success at commercial airlines. These successes are slowly permeating into general aviation through programs such as the National General Aviation Flight Information Database (NGAFID). The NGAFID is a program funded by the Federal Aviation Administration that allows general aviation operators to have the ability to collect and share de-identified flight data on an aggregate level to identify trends and increase safety margins during flight operations. This study …

Resolvent-Based And Data-Driven Analysis Of A Supersonic Rectangular Multistream Jet, Miteshkumar Thakor

Dissertations - ALL

Coherent structures play a key role in uncovering and predicting the underlying physics of complex turbulent flows. This dissertation employs data-driven and operator-based techniques to investigate spatiotemporal correlated structures of a complex supersonic multi-stream rectangular jet. The nozzle configuration comprises three primary shear layers: (i) an upper shear layer (USL) formed by the flow on the upper single-sided expansion ramp stream and the freestream, (ii) a splitter plate shear layer (SPSL) generated by the mixing of a core Mach 1.23 stream with a bypass Mach 1 stream at the splitter plate trailing edge (SPTE) and (iii) a lower shear layer …

Defending Nato’S Northern Flank: Power Projecting And Military Operations, Nate Ostdiek

Space and Defense

This review evaluates Defending NATO’s Northern Flank: Power Projection and Military Operations, edited by Lon Strauss and Njord Wegge. The volume offers a comprehensive assessment of NATO’s evolving Arctic posture, combining doctrinal analysis, historical context, and alliance dynamics. Contributions examine Russia’s military strategy, U.S. Arctic policy, and intra-alliance complexities involving Denmark, Greenland, and the Faroe Islands. While the anthology provides valuable insights into NATO’s strategic challenges, it notably underrepresents Canada’s role. Overall, it stands as a timely and rigorous contribution to understanding Arctic security and NATO’s internal decision-making amid rising geopolitical competition.

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Modeling Nato Joint Warfighting Through Space Combat Simulations, Grant Nehls, Apoorva Somani

Space and Defense

This article investigates NATO’s dependence on space systems in joint warfighting and explores the use of simulation to quantify degradation effects. Using a custom-built AFSIM model of a NATO Arctic operation, the study demonstrates how GNSS spoofing and crosslink jamming undermine data integrity, commander trust, and strike execution—even without kinetic losses. Results show that partial degradations can cause mission failure through decision paralysis. By moving beyond binary modeling, this research highlights the need for nuanced simulations to prepare NATO for contested space environments and the challenges of great power competition.

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From The Last Frontier To The Final Frontier: The Polar Regions And Space Security, Michael Lynch

Space and Defense

This article examines the intersection of Arctic geopolitics and space security amid intensifying U.S., Russian, and Chinese competition. Melting ice has opened access to resources and new sea routes, elevating the Arctic’s strategic value while increasing reliance on space-based communications, navigation, and surveillance. Yet, vulnerabilities in polar orbits, aging ground infrastructure, and dual-use facilities expose critical systems to environmental hazards and geopolitical risks. The analysis highlights modernization efforts—including SHIELD and Golden Dome—as well as enduring cooperation and rivalries, underscoring the Arctic’s role as both a frontier of opportunity and a potential flashpoint in space-enabled security.

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Same But Different: The Survivability Of Arctic-Based Russian Second-Strike Capability, July Decarpentrie

Space and Defense

This article analyzes the survivability of Russia’s second-strike capability in the Arctic through the lens of classical nuclear deterrence theory. Despite heavy commitments in Ukraine, Moscow continues to modernize its Northern Fleet and reinforce bastion defenses, underscoring the Arctic’s role as the cornerstone of its retaliatory deterrent. While these strategies mirror Cold War practices, they face unprecedented challenges from NATO expansion, multipolar competition, and advances in anti-submarine detection technologies. The study concludes that safeguarding Russia’s second-strike capability not only shapes regional security dynamics but also has broader implications for global strategic stability.

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Atomic Offsets: Nuclear Policy Shifts For Arctic States In The Wake Of Moscow’S Special Military Operation, Molly Wise, Lillian Hussong

Space and Defense

This article examines how Russia’s 2022 invasion of Ukraine has intensified nuclear reliance among Arctic states. Applying a new framework of “conventional-nuclear vulnerability,” it analyzes the nuclear policy shifts of Sweden, Finland, and Russia. The findings show that Finland and Sweden pursued NATO membership to secure nuclear guarantees, while Russia adopted riskier nuclear signaling and lowered thresholds for nuclear use. These developments highlight the growing centrality of nuclear deterrence in Arctic security, underscoring the challenges for U.S. and NATO policymakers in balancing assurance and deterrence in a volatile regional environment.

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Russian Strategic Culture And Deterrence In The Arctic, Lana Obradovic, Bethany Vailliant

Space and Defense

This study analyzes Russia’s evolving strategic culture to assess its implications for deterrence in the Arctic. It argues that Western deterrence frameworks insufficiently account for Russia’s integration of military, economic, informational, and political tools into a holistic strategy. Rooted in a siege mentality and aspirations for great power status, Russia perceives the Arctic as central to its security, economic modernization, and geopolitical influence. By situating Arctic policy within this cultural framework, the analysis highlights the need for U.S. and NATO practitioners to reassess assumptions and develop more culturally attuned deterrence strategies.

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Table Of Contents Vol. 16 No. 1, Editors Space And Defense

Space and Defense

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Front Matter, Editors Space And Defense

Space and Defense

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Space And Defense Vol. 16 No. 1 Summer 2025 Special Issue On Arctic Security (Whole Issue), Editors Space And Defense

Space and Defense

Articles that cover issues on Artic Security.

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Analyzing The Impact Of Passive Techniques On Aircraft Wing Hysteresis: An Experimental And Numerical Study, Brendan Worton

Masters Theses

This study investigates the effects of passive flow control techniques on aerodynamic hysteresis primarily in NACA 2412 (cambered) and 0012 (symmetric) wings. Computational Fluid Dynamics (CFD) was used to design and evaluate three passive techniques, including outward-facing dimples, leading-edge tubercles, and rectangular vortex generators, prior to experimental validation. These techniques demonstrated improvements in aerodynamic performance in CFD simulations and were therefore selected for wind tunnel testing to analyze their aerodynamic performance and influence on hysteresis behavior. A custom, cost-effective experimental setup was designed and developed to facilitate efficient angle-of-attack control and data acquisition. It incorporates a three-axis force sensor, stepper …

Development Of Turbulence Models For Prediction Of Hypersonic Flows Using Compressibility Corrections And Uncertainty Quantification With Emphasis On The Wray-Agarwal Model, Aidan Robert Murphy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Accurate prediction of high-speed compressible turbulent flows remains one of the most significant challenges in Computational Fluid Dynamics (CFD), especially in the realm of hypersonic vehicle design. These flow regimes involve significant aerodynamic heating and shock-wave boundary layer interactions (SBLI) which remain a significant challenge for the current CFD prediction capabilities. While Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES) provide high-fidelity solutions, their computational demands limit their usability, making the Reynolds-Averaged Navier-Stokes (RANS) equations an efficient alternative for many industrial aerodynamic applications. Traditional RANS techniques, while computationally efficient, often provide limited accuracy in high-speed flows due to the presence …

Development, Numerical Simulation, And Optimization Of Quiet Supersonic Transport Aircraft And Extension Of The Wray-Agarwal Algebraic Transition Model To Include Compressibility And Crossflow Effects, Dean Ryan-Simmons

McKelvey School of Engineering Graduate Student Theses & Dissertations

In the first part of this thesis, the goal of the research is to implement and extend multi fidelity methods for conceptual design and optimization of a commercial supersonic transport (SST). Most modern commercial aircraft operate at a cruise condition between Mach 0.7 and 0.9, as this is the optimal trade-off of flight efficiency, operational cost, and adherence of noise regulations for overland travel. Advancements in aviation propulsion fuel efficiency and design materials suggests a primary restraint on commercial supersonic transport is noise regulations. At speeds above Mach 1, the shock waves generated by the airframe are strong enough to …

Transition And Instability Characteristics Of The Separated Shear Layer Formed At Low Reynolds Number Over Three-Dimensional Irregular Rough Surface, Ganesh Kt Mr

Theses and Dissertations

The present experimental work investigates the effects of irregularly roughened surfaces and imposed streamwise pressure gradients on the topological, transitional, and instability characteristics of the laminar separated shear layer (SSL). Experiments are conducted in the low-speed wind tunnel for 𝑅𝑒𝑡=30000, based on the thickness of the airfoil model, t, and freestream turbulence intensity, fst = 0.8%. The airfoil model used in this study features a semicircular leading edge followed by a constant-thickness flat portion and a pitchable trailing-edge flap. Test conditions include two rough surfaces: sandblasted (SB) and sand-deposited (SD), and flap deflections: 𝛽=−30° and 𝛽=+30°, imposing adverse (APG) and …

Bio-Inspired Electroactive Polymer (Eap) Sensors For Surface And Canal Flow Sensing In Dynamic Environments, Nazanin Minaian

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nature can often create some of the most efficient and elegant solutions to complex problems, and engineering stands to benefit greatly from these time-tested designs. One of the more sophisticated examples of this is the lateral line system in fish: a distributed network of superficial and canal neuromasts that enables aquatic species to detect fluid disturbances with remarkable precision. This dissertation leverages that biological framework to explore the potential of electroactive polymers (EAPs), aiming not just to replicate structure, but to emulate function.Two classes of EAPs form the basis of this work: electroactive plasticized polymer gels (EPPGs) and ionic polymer-metal …

Orbital Maneuvers And Interplanetary Trajectory Design Via Reinforcement Learning, Roberto Cuéllar Rangel

Doctoral Dissertations and Master's Theses

This dissertation investigates the application of reinforcement learning (RL) to the design and optimization of low-thrust spacecraft trajectories, with an emphasis on autonomy, adaptability, and robustness in the presence of system uncertainties and unmodeled perturbations. Classical approaches to low-thrust trajectory design are predominantly grounded in optimal control theory, which relies on the availability of precise dynamical models and often requires problem-specific reformulation and solver tuning. While optimal control methods offer high accuracy under deterministic conditions, their sensitivity to stochastic disturbances and computational limitations in highly nonlinear or uncertain environments pose significant challenges for future autonomous space missions.

To address these …

Life And Performance Improvement Trenches, Thomas J. Praisner, John R. Farris, Connor Wiese

AFIT Patents

A blade outer air seal assembly includes a plurality of seal segments circumferentially disposed about an array of blades rotatable about an axis, each of the plurality of seal segments having a radially inner surface facing a tip of each blade of the array of blades, the radially inner surface having an arrangement of trenches formed therein, and a radially outer surface opposite the radially inner surface. The arrangement of trenches is disposed between 30% and 80% of a chord of a blade of the array of blades as taken at the respective tip, and the arrangement of trenches is …

Satellite Passive Ranging Metasurface Optics For Space Rendezvous And Proximity Operations, Zachary Coppens, Cameron Vo, Addison Long, Jeremy Harris

Space Dynamics Laboratory Publications

SDL Presentation on Satellite Passive Ranging Metasurface Optics for Space Rendezvous and Proximity Operations

An Inexpensive, Open, And Extensible Hardware-In-The-Loop Cubesat Test And Simulation Infrastructure, Andrew Greenberg, Glenn Lebrasseur, Max Eltzroth, Rose Edington, Anna Meneely, Maxwell Millar

Small Satellite Conference

We have developed an inexpensive, open source, and extensible hardware-in-the-loop (HIL) test and simulation system to allow even small CubeSat teams to dramatically improve their testing infrastructure to increase reliability during flight.

Design Of A Fan-Based Test Stand For Evaluating Multicopter Handling In Turbulent Flow, Salim Roig

Doctoral Dissertations and Master's Theses

With the innovation of eVTOL rotorcraft the need to analyze how turbulence-induced disturbances from orthogonal flow affect various rotorcraft configurations outside of simulations have grown significantly. To investigate the behavior of this type of flow and how it interacts with various rotorcraft configurations, a turbulent inducing test stand was designed and constructed. The test stand will have two walls of computer fans arranged in an L-shape frame, creating wind gusts that simulate the non-linear turbulent wind experienced by eVTOL. This also aids the Eagle Flight Research Center (EFRC) in their efforts to better understand how disturbances affect the handling qualities …

Calibration And Validation Of The Thermal Finite Element Model For Er120s-G Wire Arc Directed Energy Deposition Using Infrared Cameras And Thermocouples, Joshua Mykl Bassett

Theses and Dissertations

Wire Arc Directed Energy Deposition (WA-DED) is a promising additive manufacturing method for producing large metallic components with high deposition rates and low costs. However, its rapid heat input can lead to residual stress, microstructural changes, and dimensional inaccuracies. Accurate thermal modeling is essential to mitigate these effects. This study presents a thermal calibration of a finite element model (FEM) for ER120S-G using thermocouples and infrared (IR) imaging. Thermal data were gathered from three experiments to complete the calibration of the FEM . Calibration focused on tuning the Goldak heat source parameters, power efficiency, and heat transfer coefficients to minimize …