Self-Oxidation Of The Atmospheres Of Rocky Planets With Implications For The Origin Of Life, 2024 The University of Texas Rio Grande Valley
Self-Oxidation Of The Atmospheres Of Rocky Planets With Implications For The Origin Of Life, Anders Johansen, Eloi Camprubi, Elishevah Van Kooten, H. Jens Hoeijmakers
School of Integrative Biological and Chemical Sciences Faculty Publications and Presentations
Rocky planets may acquire a primordial atmosphere by the outgassing of volatiles from their magma ocean. The distribution of O between H2O, CO, and CO2 in chemical equilibrium subsequently changes significantly with decreasing temperature. We consider here two chemical models: one where CH4 and NH3 are assumed to be irrevocably destroyed by photolysis and second where these molecules persist. In the first case, we show that CO cannot coexist with H2O, since CO oxidizes at low temperatures to form CO2 and H2. In both cases, H escapes from the thermosphere within a few 10 million years by absorption of stellar …
Boosting Predictive Accuracy Of Single Particle Models For Lithium-Ion Batteries Using Machine Learning, 2024 Missouri University of Science and Technology
Boosting Predictive Accuracy Of Single Particle Models For Lithium-Ion Batteries Using Machine Learning, Emmanuel Olugbade, Jonghyun Park
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The accuracy of single particle (SP) models for lithium-ion batteries at high C-rates is constrained by lithium concentration gradients in the electrolyte, which affect ionic conductivity, overpotential, and reaction rates. This study addresses these limitations using extreme gradient boosting machine learning (ML). By training our ML model with data from a comprehensive electrochemical (P2D) model and performing sensitivity analysis on key battery parameters, we enhance predictive accuracy. Compared to conventional SP and P2D models under constant current loading, our ML-based SP model achieves similar predictive accuracy to P2D, with significant improvements in computational efficiency. Additionally, the ML-based SP model demonstrates …
Redwater Test Data, 2024 Michigan Technological University
Redwater Test Data, Paul Van Susante, Kris Zacny
Michigan Tech Research Data
The RedWater mission is to extract water from subterranean glaciers found on Mars. Honeybee robotics has contracted the PSTDL to conduct small scale tests in order to collect data on the power consumed by a high-density cartridge heater to melt through cryogenic clear ice at Martian atmospheric pressure.
A Panel Data Regression Model For Defense Merger And Acquisition Activity, 2024 USAF
A Panel Data Regression Model For Defense Merger And Acquisition Activity, Corey D. Mack, Clay Koschnick, Michael Brown, Jonathan D. Ritschel, Brandon M. Lucas
Faculty Publications
Excerpt: This paper examines the relationship between a prime contractor's financial health and its mergers and acquisitions (M&A) spending in the defense industry. It aims to provide models that give the United States Department of Defense (DoD) indications of future M&A activity, informing decision-makers and contributing to ensuring competitive markets that benefit the consumer.
The results show a significant relationship between efficiency and M&A spending, indicating that companies with lower efficiency tend to spend more on M&As. However, there was no significant relationship between M&A spending and a company's profitability or solvency. These results were consistent with previous research and …
Surrogate-Based Multidisciplinary Optimization For The Takeoff Trajectory Design Of Electric Drones, 2024 Missouri University of Science and Technology
Surrogate-Based Multidisciplinary Optimization For The Takeoff Trajectory Design Of Electric Drones, Samuel Sisk, Xiaosong Du
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electric vertical takeoff and landing (eVTOL) aircraft attract attention due to their unique characteristics of reduced noise, moderate pollutant emission, and lowered operating cost. However, the benefits of electric vehicles, including eVTOL aircraft, are critically challenged by the energy density of batteries, which prohibit long-distance tasks and broader applications. Since the takeoff process of eVTOL aircraft demands excessive energy and couples multiple subsystems (such as aerodynamics and propulsion), multidisciplinary analysis and optimization (MDAO) become essential. Conventional MDAO, however, iteratively evaluates high-fidelity simulation models, making the whole process computationally intensive. Surrogates, in lieu of simulation models, empower efficient MDAO with the …
A Robust Recurrent Neural Networks-Based Surrogate Model For Thermal History And Melt Pool Characteristics In Directed Energy Deposition, 2024 Missouri University of Science and Technology
A Robust Recurrent Neural Networks-Based Surrogate Model For Thermal History And Melt Pool Characteristics In Directed Energy Deposition, Sung Heng Wu, Usman Tariq, Ranjit Joy, Muhammad Arif Mahmood, Asad Waqar Malik, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In directed energy deposition (DED), accurately controlling and predicting melt pool characteristics is essential for ensuring desired material qualities and geometric accuracies. This paper introduces a robust surrogate model based on recurrent neural network (RNN) architectures—Long Short-Term Memory (LSTM), Bidirectional LSTM (Bi-LSTM), and Gated Recurrent Unit (GRU). Leveraging a time series dataset from multi-physics simulations and a three-factor, three-level experimental design, the model accurately predicts melt pool peak temperatures, lengths, widths, and depths under varying conditions. RNN algorithms, particularly Bi-LSTM, demonstrate high predictive accuracy, with an R-square of 0.983 for melt pool peak temperatures. For melt pool geometry, the GRU-based …
Contributions To The Understanding Of Turbulent Boundary Layers Over Curved Walls, 2024 Embry-Riddle Aeronautical University
Contributions To The Understanding Of Turbulent Boundary Layers Over Curved Walls, Nicholas Zhu
Doctoral Dissertations and Master's Theses
A wind tunnel campaign was conducted to investigate the DARPA Suboff boundary layer. To emphasize the axisymmetric boundary layer, the generic submarine model's sail, appendages, and propeller were omitted. The study focused on the afterbody from 70–95% of the model length to examine the concurrent pressure gradient and wall curvature effects, which are commonplace in engineering. Three particle image velocimetry (PIV) configurations were employed to measure the boundary layer in detail: one spanned the entire afterbody, another had narrow strips sampled at 16 kHz, and the third used two simultaneous orthogonal measurement planes. Considerable effort was made to reduce the …
End-To-End Full-Width Induction Welding Of Unidirectional Tape-Based Thermoplastic Composites, 2024 University of South Carolina
End-To-End Full-Width Induction Welding Of Unidirectional Tape-Based Thermoplastic Composites, Jaspreet Singh Pandher
Theses and Dissertations
The current large scale application of thermoset composite materials in large, twin aisle, civil transport aircraft have resulted in significant performance enhancements, such as aerodynamic efficiency, weight reduction, and durability. These large aircraft are, however, produced in relatively low numbers. For the next generation smaller single aisle aircraft, large scale applications of composites are of interest in the airframe. Application of composites in single aisle aircraft will require not only proof of similar and/or significant performance improvements, but also proof of adequate manufacturing rates. One option to achieve both is large scale application of thermoplastic instead of thermoset composites.
Thermoplastic …
The Study And Development Of Autonomous Scarf Repair For Composite Structures: A Focus On Advanced Air Mobility Vehicles, 2024 University of South Carolina
The Study And Development Of Autonomous Scarf Repair For Composite Structures: A Focus On Advanced Air Mobility Vehicles, Stephen Hilton
Theses and Dissertations
“I’m sorry I haven’t been able to truly give you a solution to thermoplastic repair” – Arnt. Director GKN Global Tech Center, 2023
The aerospace industry has a prevalence of composite materials due to their outstanding benefits to the mechanical properties of structures while serving to reduce the overall structure weight. With the development of the Advanced Air Mobility market, there is an anticipated growth in the number of composite structures. Also, with the manufacturing environment of the 21st century, these composite structures are more and more being made using thermoplastic composites that can be recycled at the end of …
High-Rate Production Of Thermoplastic Composite Structures For Urban Air Mobility Vehicles Utilizing Fastener-Free Assembly Methods, 2024 University of South Carolina
High-Rate Production Of Thermoplastic Composite Structures For Urban Air Mobility Vehicles Utilizing Fastener-Free Assembly Methods, Robert H. Shumpert
Theses and Dissertations
This study aimed to develop a manufacturing plan for a Thermoplastic fiber-reinforced propeller blade for urban air mobility applications. This propeller blade offer a few unique challenges including the complex geometries of the blade. Another important aspect of the blade is using fusion bonding methods to increase the strength of joints in the product while reducing weight from fasteners and adhesives. This manufacturing process will be validated by producing a physical demonstrator to ascertain the efficacy of the manufacturing techniques used. First, the techniques that will make up the manufacturing plan must be selected. To do this, a review of …
Heat Transfer To Arrays Of Oscillating Impingement Jets, 2024 Embry-Riddle Aeronautical University
Heat Transfer To Arrays Of Oscillating Impingement Jets, Alex Q. Clay
Doctoral Dissertations and Master's Theses
In gas turbine engines, the desire to increase turbine entry temperatures has become more relevant in order to increase engine efficiency. However, materials used in these engines can only withstand temperatures that are so high. Because of this, the ability to cool hot section components will always limit operating temperatures. Impingement cooling jets have become a common way of cooling due to the high rates of heat transfer that can be achieved. However, previous research has shown that the interaction of impingement jets with cylinder wake can improve the intensity and uniformity of heat transfer. The goal of this study …
Enhancing Crossflow Dynamics Through The Gas Injection From Multiple Cylinders, 2024 University of Wroclaw
Enhancing Crossflow Dynamics Through The Gas Injection From Multiple Cylinders, Sahrish B. Naqvi, Sadia Siddiqa, Maciej Matyka, Rama S. R. Gorla, Md. Mamum Molla
Faculty Publications
We investigate unsteady, two-dimensional laminar fluid flow around cylinders, focusing on understanding the impact of injecting methane gas through two diametrically opposite arcs on the cylinder in the crossflow of the second fluid. This study encompasses applications in mixing and dispersion, which are crucial in various technological and natural processes. Our analysis addresses velocity field’s contribution to the spatiotemporal distribution of transported quantities. We observed that mixing induces a transition from laminar to turbulent flow. Depending on the injected-to-crossflow velocity ratios, the wake vortices downstream of cylinder arrays separate from or connect to the injected gas. This phenomenon significantly impacts …
Cislunar Optimal Robust Trajectory Design With Corrective Maneuvers, 2024 Utah State University
Cislunar Optimal Robust Trajectory Design With Corrective Maneuvers, Scott J. Kelly
All Graduate Theses and Dissertations, Fall 2023 to Present
One common method for determining how to get from point A to point B is by finding the most fuel-efficient path. This is a common method for spacecraft trajectory designers also. Without any random or unexpected occurrences this path is called the deterministic optimal trajectory. Sometimes unexpected events happen that result in deviating from the most fuel-efficient path; while driving, you may encounter a detour. Naturally, we tend to return to the original fuel-efficient path and continue the journey. Similar deviations happen in space. The rocket delivering a spacecraft to orbit likely will not deliver exactly to the intended starting …
Trade-Offs In Lighting For Dic Strain Measurements In Vibration-Based Fatigue Testing, 2024 Utah State University
Trade-Offs In Lighting For Dic Strain Measurements In Vibration-Based Fatigue Testing, Jacob R. Rigby
All Graduate Theses and Dissertations, Fall 2023 to Present
Vibration based fatigue testing offers a fast and efficient method for determining the breaking point of a material. This method often uses a device, called a strain gage, to measure the deformation of a test sample at a single spot on the test sample. However, these strain gages often break before testing is complete. To overcome this premature break, a laser vibrometer is often used to measure the amount of movement or the speed of the test sample throughout the vibration test. The deformation measured by the strain gage is compared against the amount of movement or velocity of the …
Ultrashort Pulsed Laser Treatment Is Effective At Sterilizing Metal Surfaces For Planetary Protection, 2024 University of Nebraska-Lincoln
Ultrashort Pulsed Laser Treatment Is Effective At Sterilizing Metal Surfaces For Planetary Protection, Kaleb Mcquillan
Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research
To prevent forward contamination from microbes aboard spacecraft intended for exploration of solar system bodies there is a need for effective sterilization methods. However, current techniques are both time-consuming and expensive. For example, dry heat sterilization requires removal from the assembly site and several days of treatment. Furthermore, some components such as optics and electronics are not compatible with current sterilization techniques. In this thesis, a novel femtosecond laser surface processing technique for the rapid sterilization of spacecraft hardware is reported. Femtosecond lasers produce extremely high photon fluxes (1029 photons/s*cm2, ~0.03 J/cm2) in extremely short …
Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, 2024 Missouri University of Science and Technology
Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 …
A Convex Approach To Advanced Air Mobility Trajectory Optimization, 2024 University of Tennessee, Knoxville
A Convex Approach To Advanced Air Mobility Trajectory Optimization, Yufei Wu
Doctoral Dissertations
This dissertation addresses the challenge of real-time trajectory optimization for electric Vertical Take-Off and Landing (eVTOL) vehicles within the framework of Advanced Air Mobility (AAM). With urban airspaces becoming increasingly crowded, ensuring the safety, efficiency, and feasibility of eVTOL operations is crucial. This research primarily focuses on the development and application of convex optimization techniques to solve trajectory optimization problems that not only enhance operational capabilities but also ensure adherence to stringent safety and efficiency standards.
The study is structured into several critical analyses and methodological developments across multiple chapters. In the first chapter, I introduce a multi-phase trajectory optimization …
Bi-Modal Excitation Of A Supersonic Rectangular Jet, 2024 Embry-Riddle Aeronautical University
Bi-Modal Excitation Of A Supersonic Rectangular Jet, Benjamin Malczewski
Doctoral Dissertations and Master's Theses
This work addresses the issue of supersonic rectangular jet noise via bi-modal excitation. A Mach 1.5 heated rectangular jet with a 2:1 aspect ratio is considered. Theoretical work is presented in which a Reduced-Order Model (ROM) is used in conjunction with the Linearized Euler Equations to predict the nonlinear growth and decay of various frequencies due to the interaction between harmonically related modes and the mean flow. Scope is limited to a symmetric disturbance. The case of no interaction is used to help identify a dominant coherent structure, referred to as “f”. For the symmetric disturbance, a Strouhal number of …
Conceptual Propellant Feed System For Electrospray Thrusters And An Exploration Into 3d Printed Millifluidic Manifolds, 2024 University of Tennessee, Knoxville
Conceptual Propellant Feed System For Electrospray Thrusters And An Exploration Into 3d Printed Millifluidic Manifolds, Tyler M. Sundstrom
Masters Theses
The miniaturization of satellites has led to a new era of miniaturized spacecraft technology, which includes propulsion systems. The full potential of CubeSats will be realized once they are equipped with miniaturized thrusters. One option being developed at the University of Tennessee Space Institute (UTSI) is a miniature electrospray device, Micro Scalable Thrusters for Adaptive Mission Profiles in Space (µSTAMPS). This device operates via electrospray principles and utilizes an ionic liquid (IL) propellant. µSTAMPS aims to provide CubeSats with maneuvering capabilities, including rapid deorbiting, station-keeping, and collision avoidance maneuvers (CAMs). An internal propellant reservoir can deliver enough propellant for CAMs; …
Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, 2024 Air Force Institute of Technology
Tension–Compression Fatigue Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Marina B. Ruggles-Wrenn, Joshua Schmidt
Faculty Publications
Fully reversed tension–compression fatigue of a hybrid material comprising polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC) was investigated. The PMC portion had a polyimide matrix reinforced with 15 plies of carbon fibers woven in an eight-harness satin weave (8HSW). The CMC portion had three plies of a quartz-fiber 8HSW fabric in a zirconia-based ceramic matrix. The hybrid PMC/CMC was developed for use in aerospace thermal protection systems (TPS). Hence, the experimental setup aimed to simulate the TPS service environment—the CMC side was kept at 329 °C, whereas the PMC side was open to laboratory air. Compression …