Aerospace Engineering Commons^™

Understanding Policy Transfer Under Decomposition And Coordination: Sequential Reinforcement Learning With Relaxation-Based Feasibility Control, Aannand Lal

All Theses

This thesis investigates how decomposition and coordination (D&C) choices influence exploration, learning, and transfer in reinforcement learning (RL) based design frameworks. A unified methodology is developed to evaluate generality under decomposition and to demonstrate sequential coordination on a representative physical task. The generality study holds the underlying physics constant while varying problem presentation - specifically scalarization weights, objective orientations, and feasibility handling. A train-evaluate matrix is constructed in which each trained policy is assessed across all alternative decompositions. Set-based diagnostics quantify generality through exact-match identity, Jaccard similarity of distinct feasible states, total feasible coverage, and Pareto-front quality. Results show that …

2025 Summer-Fall Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for summer and fall 2025. Includes photographs, upcoming events, recent publications, and student profiles.

Short-Arc Angles-Only Initial Orbit Determination For Leo And Geo Objects Using A Genetic Algorithm, Joseph R. Piini

Master's Theses

An ever-growing interest in utilizing space for scientific, commercial, and defense applications has led to an exponential rise in orbital debris recent years. With this sharp increase in space objects comes a greatly increased risk of potential collisions, necessitating an increase in Space Situational Awareness. In order to best mitigate the risk of future collisions in an increasingly congested space environment, it is crucial to be able to accurately determine the orbits of these new objects for trajectory tracking. This process is initial orbit determination (IOD), and is especially difficult when only observation angles are available for short observation times. …

When Textures Trim Drag: Micro-Structures For Adaptive Drag Reduction And Flow Authority, Miguel Angel Olvera

Theses and Dissertations

Turbulent boundary layers are a major source of drag and performance loss. This thesis investigates Triangular Porous Texturing (TPT), apex-forward microstructures with optional bleed channels, as a passive concept for simultaneously reducing skin friction and strengthening boundary layer momentum near separation. Low-speed wind tunnel tests are conducted over tripped turbulent boundary layers on flat plates with three surfaces: a smooth baseline, a solid-crest TPT array isolating the knife-edge “slip-cut” effect, and a porous-bleed TPT array whose paired micro-channels vent a small fraction of the free stream. Time-resolved PIV provides wall-normal velocity fields; skin friction is inferred from near-wall shear, and …

Design And Assessment Of A Single-Blade Rotary Wing For Use In Vertical Takeoff And Landing (Vtol) Aircraft, William C. Mcmasters

Mechanical & Aerospace Engineering Theses & Dissertations

A single-bladed propeller was designed to determine its efficacy in increasing efficiency of quadplane aircraft in the cruise configuration while still providing sufficient vertical lift for the vertical takeoff portion of flight. Aerodynamic theory predicts higher efficiency for single-blade propellers, resulting in a lower power requirement. A counter-weighted single-blade was modeled after a 10x5 model aircraft propeller used in small unmanned vehicles with a steel counterweight to balance centrifugal forces. The propeller was tested in the ODU wind tunnel to determine performance at various Advance Ratios (J). The research suggests that single-blade propellers show comparable performance compared to two-bladed propellers …

Thermal Management With Supercritical Carbon Dioxide Under Extreme Applications, Devon Hardy

Doctoral Dissertations and Master's Theses

A unique challenge in thermal system design is minimizing the power required to operate cooling systems while maintaining effective heat removal. Traditional cooling systems utilize single-phase fluids where the heat transfer mechanisms are well understood. To meet a variety of cooling demands, a range of technologies are available, including microchannel forced convection, jet impingement, porous media, nanofluids, pin fin arrays, and film cooling, each offering distinct advantages and limitations. While the performance of single- or two-phase cooling systems are generally predictable, in extreme thermal environments, new cooling solutions are needed to improve overall system efficiency and reliability.

Supercritical fluids, particularly …

Propeller Noise Prediction Of An Urban Air Mobility Vehicle In Urban Environment, Jie Hua

Doctoral Dissertations and Master's Theses

Urban Air Mobility (UAM) vehicles operate in complex, unsteady aerodynamic environments where wake interactions, gust and turbulence significantly affect both performance and noise generation. Understanding these mechanisms is critical for developing quieter and more efficient eVTOL systems that meet future community noise and certification requirements. This dissertation focuses on the high-fidelity numerical investigation of propeller noise in three representative unsteady loading scenarios: (i) transition (tilt) flight, (ii) edgewise inflow, and (iii) wake–propeller interaction. Each case emphasizes different physical mechanisms that dominate noise generation in UAM operations. Hybrid turbulence-resolving approaches—Detached Eddy Simulation (DES) and Delayed Detached Eddy Simulation (DDES)—are coupled with …

Notes For Contributors, Editors Space And Defense

Space and Defense

No abstract provided.

Review Article: International Relations: State Of The Field. Paul R. Viotti’S Kenneth Waltz: An Intellectual Biography (Ny: Columbia University Press, 2023)., Damon Coletta

Space and Defense

In this review essay, Damon Coletta examines Paul R. Viotti’s Kenneth Waltz: An Intellectual Biography (Columbia University Press, 2023), positioning it as both a tribute to and a reexamination of one of International Relations’ most influential theorists. Viotti, a former student of Waltz, reconstructs the intellectual development of structural realism—tracing its philosophical and methodological roots from Man, the State, and War (1959) to Theory of International Politics (1979)—while situating Waltz’s scholarship within the geopolitical and academic transformations of the Cold War era. Coletta highlights Viotti’s skillful balance between biography and disciplinary analysis, showing how Waltz’s systemic approach to international politics …

Review Article: Monetary Power And National Security. A 10th Anniversary Review Of Paul R. Viotti’S The Dollar And National Security: The Monetary Component Of Hard Power (Stanford, Ca: Stanford University Press, 2014), Ricardo Crespo

Space and Defense

In this ten-year retrospective, Ricardo A. Crespo reassesses Paul R. Viotti’s The Dollar and National Security (2014) as a foundational text bridging the fields of monetary policy and national security. Viotti’s central thesis—that military power ultimately depends on a stable and privileged monetary foundation—has only grown more relevant amid today’s weaponization of finance and the geopolitics of sanctions. Crespo highlights Viotti’s argument that sustaining the U.S. dollar’s global dominance requires cooperative security and international consensus, noting how historical parallels—from the sterling gold standard to Bretton Woods—illustrate the fragility of monetary hegemony under fiscal mismanagement or political fragmentation. The review situates …

Plan To Fail By Failing To Plan: Deterring Prc Nuclear Force Expansion, Mark Tang, Grace Buettner

Space and Defense

This article argues that the United States must adapt its nuclear deterrence strategy to counter the People’s Republic of China’s (PRC) accelerating nuclear force expansion. As Beijing seeks to achieve nuclear parity with Washington—projecting up to 1,500 warheads by 2035—the authors contend that U.S. strategy must evolve from Cold War-era models to meet the Indo-Pacific’s unique strategic challenges. They propose the establishment of a Pacific Air Forces (PACAF) A-10 Strategic Deterrence and Nuclear Integration Division, modeled after its European counterpart, to enhance regional nuclear planning, integration, and allied assurance. The paper emphasizes the concept of escalation domination, arguing …

Earth’S Orbital Prison: Codifying Customary Law To Prevent Environmental Catastrophe In Space, Jacob Cook

Space and Defense

This article argues that the accelerating proliferation of space debris in low Earth orbit (LEO) poses an existential threat to the sustainability of the orbital environment—one comparable in strategic gravity to nuclear deterrence during the Cold War. Drawing on liberal internationalist theory and the concept of Mutually Assured Destruction (MAD), the paper asserts that deliberate satellite destruction through anti-satellite (ASAT) testing and negligent debris generation risk triggering a self-sustaining cascade of collisions known as the Kessler Syndrome. Existing treaties, including the Outer Space Treaty and the Artemis Accords, lack enforceable mechanisms to prevent such catastrophic harm. To fill this …

Enabling The Decisive Advantage, Mallory Stewart

Space and Defense

In her keynote address at the 2025 USSPACECOM Legal Conference, former Assistant Secretary of State Mallory Stewart argues that law, norms, and international cooperation are central to maintaining the United States’ “decisive advantage” in outer space. She emphasizes that rules and standards—far from constraining innovation or strategic flexibility—enhance predictability, reduce risk, and empower responsible competition. Stewart highlights the success of initiatives such as the Artemis Accords, the U.S. commitment to forgo destructive direct-ascent anti-satellite (ASAT) tests, and the global expansion of Space Situational Awareness (SSA) agreements as examples of how legal and normative frameworks reinforce stability and collaboration. She …

Space, Law, And National Security, Stephen Whiting

Space and Defense

In his address to the 2025 USSPACECOM Legal Conference, General Stephen Whiting underscores the indispensable role of legal professionals in shaping the future of military space operations and maintaining the rules-based international order in an increasingly contested domain. He outlines the rapid transformation of the space environment driven by commercial innovation, technological proliferation, and the accelerating threat landscape posed by adversaries such as China and Russia. The speech highlights U.S. Space Command’s three “moral responsibilities”: ensuring the delivery of space capabilities to the joint force and allies, protecting and defending critical space assets, and safeguarding the joint force from space-enabled …

Allied Abandonment And Nuclear Proliferation: Lessons From South Korea’S Secret Nuclear Program, Joseph W. Brown

Space and Defense

This article examines South Korea’s clandestine nuclear weapons program of the 1970s as a historical case study for understanding how perceptions of allied abandonment can drive nuclear proliferation. Drawing on alliance theory and archival evidence, the paper situates Seoul’s nuclear ambitions within the context of U.S. burden-shifting under the Nixon Doctrine, subsequent troop withdrawals, and diplomatic retrenchment across East Asia. Despite the continued U.S. military presence, South Korean leaders interpreted American rhetoric and policy actions as signaling a waning commitment to the alliance, prompting the initiation of a secret weapons program under President Park Chung-hee. The study identifies two enduring …

In Defense Of Space Offense, Alexander R. Kleitz

Space and Defense

This article argues that in the unique physical and operational environment of outer space, offensive operations hold intrinsic advantages over defensive ones. Drawing upon classical military theorists such as Clausewitz and Corbett, the author contends that the traditional dominance of the defensive form of war—rooted in terrestrial conditions—does not extend to celestial conflict. The transparency and remoteness of the space domain neutralize key defensive benefits, such as proximity to supply bases, concealment, and fortified positions, while also diminishing the factors that typically cause terrestrial offensives to culminate. Consequently, space conflict favors the side that seizes and maintains the initiative through …

Raising Public Awareness On Space Themes: Analysis Of Brazilian Space Policy Using Data From Google Trends, Andrea Felippe Cabello, Michele Melo

Space and Defense

This study examines whether Brazil’s national space policy goal of increasing public awareness of space activities has been met, using Google Trends data as a proxy for public interest. While public perception surveys are scarce outside the United States, web-based data provide a cost-effective and timely alternative for gauging public engagement. The authors analyzed two decades (2004–2024) of Brazilian search activity related to space topics, institutions, technologies, companies, and missions. Results show no clear upward trend in public interest, suggesting that Brazil’s stated policy objectives of raising awareness have not yet translated into measurable outcomes. Although searches related to government …

Costly Signals In Space: Increasing Credibility Via Strategic Disclosure, Wendy N. Whitman Cobb

Space and Defense

As space becomes an increasingly vital domain for national security, debates persist about how much secrecy should surround U.S. military space programs. This article argues that the strategic declassification and disclosure of selected space capabilities can strengthen U.S. deterrence by enhancing the credibility of deterrent threats. Drawing from theories of costly signaling and audience costs, the paper introduces strategic disclosure as a novel form of costly signal. Such disclosure imposes bureaucratic and operational costs while exposing capabilities to potential adversary countermeasures—thereby demonstrating resolve and seriousness of intent. In tandem, greater public transparency about space programs cultivates informed domestic audiences capable …

Space And Defense Vol. 16 No. 2 Editor's Note, Damon Coletta

Space and Defense

No abstract provided.

Space And Defense Vol. 16 No. 2 Table Of Contents, Editors Space And Defense

Space and Defense

No abstract provided.

Space And Defense Vol. 16 No. 2 Front Matter, Editors Space And Defense

Space and Defense

No abstract provided.

Space & Defense Volume 16 Issue 2 Fall 2025 (Whole Issue), Editors Space And Defense

Space and Defense

No abstract provided.

Electronic Structure Prediction Of Medium And High Entropy Alloys Across Composition Space, Shashank Pathrudkar, Stephanie Taylor, Abhishek Keripale, Abhijeet S. Gangan, Ponkrshnan Thiagarajan, Shivang Agarwal, Jaime Marian, Susanta Ghosh, Amartya S. Banerjee

Michigan Tech Publications

We propose machine learning (ML) models to predict the electron density — the fundamental unknown of a material’s ground state — across the composition space of concentrated alloys. From this, other physical properties can be inferred, enabling accelerated exploration. A significant challenge is that the number of descriptors and sampled compositions required for accurate prediction grows rapidly with species. To address this, we employ Bayesian Active Learning (AL), which minimizes training data requirements by leveraging uncertainty quantification capabilities of Bayesian Neural Networks. Compared to the strategic tessellation of the composition space, Bayesian-AL reduces the number of training data points by …

Preliminary Investigation Of Cislunar Disposal Reachability Via Electric Propulsion For Selected L2 Lagrange Point Orbit Families, Ryan M. Sargent, Robert A. Bettinger, Carl R. Hartsfield

Faculty Publications

This paper investigates the disposal of end-of-life spacecraft from selected orbit families in the Earth-Moon system, specifically the L₂ Lyapunov and Halo families. Rather than focusing on impulsive burns with chemical propulsion systems, this paper examines disposal using continuous thrust generated by Hall thrusters, a form of electric propulsion. Leveraging the Circular Restricted Three Body Problem (CR3BP) as the dynamical framework, various levels of ΔV are evaluated in single-maximum burn and multiple-burn concepts of operation to evaluate the potential for spacecraft minimizing their transit of cislunar space and reaching the Earth’s gravitational sphere of influence in order to enter …

Simulation Of Rocket Response To Electromagnetic Environments Using Finite Element Modeling, Eden Powers

Fall Showcase for Research and Creative Inquiry

The purpose of this project is to develop a rocket model in FEMAP with NX-Nastran to simulate how a rocket might respond when exposed to external electromagnetic conditions. A simplified model of the SpaceX Starship will be constructed and analyzed to explore how various electromagnetic conditions interact with the rocket’s materials and geometry.

Adaptive Pi Control Using Recursive Least Squares For Centrifugal Pump Pipeline Systems, David A. Brattley, Wayne Weaver

Michigan Tech Publications

Pipeline transportation of petroleum products remains one of the safest and most efficient methods of bulk energy delivery, yet overpressure events continue to pose serious operational and regulatory challenges. Traditional fixed-gain PI controllers, commonly used with centrifugal pump drives, cannot adapt to varying product densities or transient disturbances such as valve closures that generate water hammer. This paper proposes a self-tuning adaptive controller based on Recursive Least Squares (RLS) parameter estimation to improve safety and efficiency in pipeline pump operations. A nonlinear simulation model of a centrifugal pump driven by an induction motor is developed, incorporating pipeline friction losses via …

Mesopause-Region Gravity Wave Activity Due To Tropical Convection As Observed By Awe, Jeffrey M. Forbes, Xiaoli Zhang, Jiarong Zhang, Stephen D. Eckermann, Yucheng Zhao, Pierre-Dominique Pautet, Jun Ma, Ludger Scherliess, Michael J. Taylor

Space Dynamics Laboratory Publications

Mesopause-region (∼ 87 km) gravity waves (GWs) generated by tropical convection are investigated within the four longitude sectors encompassing Africa, the Indian Ocean, the Intertropical Convergence Zone, and South America during the Dec 2023– Feb 2024 Southern Hemisphere monsoon season. Variances (Q_v) in the OH Q-line emission measured by the Atmospheric Waves Experiment (AWE) capture GW activity, and precipitation rates (PR) from the Global Precipitation Measurement (GPM) Mission identify regions of convective activity. The zonal component of GWs comprising the Q_v between 10°S-10°N primarily propagate eastward. The Q_v distributions are latitudinally-shifted and more confined in …

Numerical Study On Flow Separation And Performance Characteristics Of Slot Nozzle, Chase Charpentier

Doctoral Dissertations and Master's Theses

The altitude compensating nozzle (ACN) is a type of rocket nozzle or engine that tries to minimize the negative effects of overexpansion at low altitudes. There are many forms of ACN's but most of them are heavier than traditional bell nozzles, alter the geometry of the nozzle, which requires extensive research into optimizing the new geometry, or require complex systems that can lead to structural, heating, or material problems. Out of the ACN's, the slot nozzle is a passive ACN that builds upon the bell nozzle and requires no additional weight or complex systems.

This slot nozzle is comprised of …

Exploratory Study Of Semiconductor Nanomembranes In Em Applications, Grant D. Heileman

Electrical and Computer Engineering ETDs

Antenna systems are a cornerstone of modern technologies, playing an increasingly vital role in their advancement. As demand for compact, high-performance, and adaptable communication platforms grows reconfigurable antenna technologies are becoming essential. This research explores a novel front-end reconfigurable antenna system (FERAS) architecture that leverages the mechanical flexibility and photoconductive behavior of semiconductor nanomembrane (SNM) devices. By exploiting the emergent properties of ultra-thin silicon (Si) or gallium arsenide (GaAs) nanomaterials and optically exciting these samples using vertical-cavity surface-emitting laser (VCSEL) arrays, this study develops lightweight, low-cost, deployable antenna structures for satellite communications, remote sensing, GPS, and radar. Despite their significant …

Sustainable Practices For Aircraft Decommissioning And Recycling In A Circular Aviation Economy, Eva Maleviti, Dimitra Papadaki

Publications

The aviation industry requires a series of actions that will transform its current status, aiming for sustainable operations. Aviation’s end-of-life stream is a pivotal lever for circularity, yet current dismantling and recycling practices leave significant value unrealized. Circular Economy could be considered as a transformational approach to the aviation industry and address its environmental and economic challenges, meeting sustainability principles. This study conducts a PRISMA-guided qualitative systematic review across academic and industry sources to synthesize regulations, technologies, and economics of aircraft decommissioning. It aims to quantify material recovery potential and environmental gains at the aircraft level and assess technology readiness …