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Theses and Dissertations

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Full-Text Articles in Engineering

Suitability Of Earth-Moon Triangular Lagrange Point Orbits For Space Situational Awareness, Eric P. Burkhart Mar 2023

Suitability Of Earth-Moon Triangular Lagrange Point Orbits For Space Situational Awareness, Eric P. Burkhart

Theses and Dissertations

The second space race is looming on the horizon, and the Moon is again at center stage. All major space fairing nations have plans for future Lunar exploration, but this time with plans to stay. NASA’s Artemis program plans to put humans back on the Moon in 2025 and establish a Lunar base on the South pole in the 2030s. Meanwhile, China has landed a rover on the far side of the moon with a communications relay satellite in a halo orbit around the L2 Lagrange point, and partnered with Russia to build a Lunar research station on the Lunar …

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Gaseous Fuel Combustion In A Small Turbojet, Katherine A. Ashton Mar 2023

Gaseous Fuel Combustion In A Small Turbojet, Katherine A. Ashton

Theses and Dissertations

This project set out to test the suitability of natural gas as an aviation fuel by comparing how a small turbojet performed when run on traditional jet fuel versus methane. A JetCat P400, originally designed for jet fuel, was modified to run on methane. The modifications made did not succeed at getting the engine to run at normal operating speed on methane, but did get the engine to run at normal operating speeds using ethylene and ethane. It was determined a fuel and air mixing problem was hindering the engine performance when run on methane Future studies improving the fuel …

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Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite With Quasi-Isotropic Layup, Brian Matthew Pudlo Mar 2023

Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite With Quasi-Isotropic Layup, Brian Matthew Pudlo

Theses and Dissertations

Carbon nanotubes (CNTs) exhibit outstanding mechanical, electrical, and thermal properties, but are a challenge to effectively implement into macroscopic composites for aerospace applications. This research investigates the mechanical properties and performance of a newly developed hybrid NanoStitch composite, alongside a control polymer matrix composite, at room temperature. Both composite material systems investigated in this work have quasi-isotropic layup. Monotonic tension-tofailure, tension-tension fatigue, and creep tests were performed to characterize the performance of the composites under cyclic and sustained loading. Experimental results obtained for the quasi-isotropic NanoStitch composite were compared to those obtained for the quasi-isotropic control composite. The properties and …

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Probability Of Agreement As A Simulation Validation Methodology, Matthew C. Ledwith Mar 2023

Probability Of Agreement As A Simulation Validation Methodology, Matthew C. Ledwith

Theses and Dissertations

Determining whether a simulation model is operationally valid requires the rigorous assessment of agreement between observed functional responses of the simulation model and the corresponding real world system or process of interest. This research seeks to extend and formulate the probability of agreement approach to the operational validation of simulation models. The first paper provides a methodological approach and an initial demonstration which leverages bootstrapping to overcome situations where one’s ability to collect real-world data is limited. The second paper extends the probability of agreement approach to account for second-order heteroscedastic variability structures and establishes a weighted probability of agreement …

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A Reinforcement Learning Approach To A Beyond Visual Range Air Combat Maneuvering Problem, Caleb A. Taylor Mar 2023

A Reinforcement Learning Approach To A Beyond Visual Range Air Combat Maneuvering Problem, Caleb A. Taylor

Theses and Dissertations

A one-versus-one air combat maneuvering problem is considered wherein a friendly autonomous aircraft must engage and defeat an adversary autonomous aircraft in a beyond visual range environment. The Advanced Framework for Simulation, Integration, and Modeling (AFSIM) is leveraged to model the complex and interdependent operations of aircraft, sensors, and weapons utilized in beyond visual range air combat. We formulate a Markov decision process to obtain high-quality decision policies wherein our autonomous aircraft makes maneuvering and missile firing decisions. We utilize a reinforcement learning solution procedure that implements a linear value function approximation to represent state-decision pairs due to the high …

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Effects Of Calibration Errors On Dropped-Channel Polarimetric Synthetic Aperture Radar, Jacob C. Morrison Mar 2023

Effects Of Calibration Errors On Dropped-Channel Polarimetric Synthetic Aperture Radar, Jacob C. Morrison

Theses and Dissertations

Compressed Sensing (CS) is a mathematical technique that can be applied to sparse data sets to allow for sub-Nyquist sampling. DCPCS is a CS technique that recovers the signal from unmeasured polarisation channels due to antenna crosstalk coupling the information onto the remaining channels. DCPCS reduces data storage/transmission and receiver hardware requirements. This thesis examines the robustness of DCPCS to calibration errors on the antenna crosstalk matrix. Although the antenna design problem is relaxed to a large region of acceptable crosstalk values, very accurate calibration may be required in a monostatic radar. This thesis also looks at the importance of …

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Long-Term Asset Prioritization To Support District Planning, Melissa R. Sallberg Mar 2023

Long-Term Asset Prioritization To Support District Planning, Melissa R. Sallberg

Theses and Dissertations

The United States Air Force (USAF) relies on its installations to project military power across the globe. However, due to the deferred infrastructure maintenance and recapitalization backlog of $33 billion as of 2019 (Wilson & Goldfein, 2019), it is more critical than ever for base-level community planners to focus their attention to the projects that will achieve each installation’s long-term goals. The recent incorporation of asset management principles into the USAF District Planning Process allows a unique opportunity to improve the existing scoring model for a holistic look at what matters to enterprise leaders and community planners making the plans …

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Sea Level Rise Impacts On Wastewater Treatment Plants And Their Social Vulnerability Differences, David S. P. Robinson Mar 2023

Sea Level Rise Impacts On Wastewater Treatment Plants And Their Social Vulnerability Differences, David S. P. Robinson

Theses and Dissertations

Many of the United States’ major cities that have a high population are located along the coast. The number of people residing in low elevation coastal areas, be-low 10 meters, is increasing. Coastal areas may be affected by various short- and long-term climate hazards, such as sea level rise (SLR). Climate change induced SLR will threaten residents and infrastructure in low-lying coastal areas. A household’s capacity to respond to hazards is highly dependent on its socio-demographic situation which determines its social vulnerability. Wastewater treatment facilities area particularly critical piece of infrastructure often located in low-lying areas due to gravity fed …

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Validation Of Digital System Models, James R. Winton Mar 2023

Validation Of Digital System Models, James R. Winton

Theses and Dissertations

The Department of Defense is undergoing a Digital Transformation driven by Digital Engineering and Model-Based Systems Engineering. Document-based processes are being replaced by digital artifacts, pedigreed data, and an Authoritative Source of Truth for a system across its life cycle. As traditional Design-Build-Test transitions to a Model-Analyze-Build methodology, digital models will proliferate throughout the enterprise and require novel validation processes earlier in the development timeline. A new definition for digital system model validation is proposed to address the identified shortcomings in existing guidance. The proposed validation framework leverages the Systems Modeling Language, use cases, requirements, test cases, and a custom …

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Inducing Sparsity Within High-Dimensional Remote Sensing Modalities For Lightning Prediction, Grace E. Metzgar Mar 2023

Inducing Sparsity Within High-Dimensional Remote Sensing Modalities For Lightning Prediction, Grace E. Metzgar

Theses and Dissertations

The uncertainty of lightning constantly threatens many weather-sensitive fields where the slightest presence of lightning can endanger valuable personnel and assets. The consequences of delaying operations have incited the research of methods that can accurately predict the location of future lightning strikes from the current weather conditions. High-dimensional remote sensing modalities contain information capable of detecting significant patterns and intensities within storms that could indicate the presence of lightning. This thesis induces sparsity into convolutional neural networks (CNNs) and remote sensing modalities through a combination of regularization and tensor decomposition techniques to call attention to sparse features that are most …

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The Aerial Refueling Asset Basing And Assignment Problem, Camryn E. Deames Mar 2023

The Aerial Refueling Asset Basing And Assignment Problem, Camryn E. Deames

Theses and Dissertations

With growing tensions in the European theatre and Indo-Pacific theatre, the constraints of aerial refueling impede the missions of Air Mobility Command and USTRANSCOM in their execution of both the National Security Strategy and National Defense Strategy. Introducing and integrating semi-autonomous aerial refueling aircraft is a logical next step due to advantages in endurance, survivability, runway requirements, and fuel offloading capacity. This research frames the Aerial Refueling Asset Basing and Assignment Problem with two model approaches: a baseline model and a fuel shuttle concept model. Whereas the former model considers instances with only manned refuelers or only semi-autonomous refuelers, the …

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Automated Registration Of Titanium Metal Imaging Of Aircraft Components Using Deep Learning Techniques, Nathan A. Johnston Mar 2023

Automated Registration Of Titanium Metal Imaging Of Aircraft Components Using Deep Learning Techniques, Nathan A. Johnston

Theses and Dissertations

Studies have shown a connection between early catastrophic engine failures with microtexture regions (MTRs) of a specific size and orientation on the titanium metal engine components. The MTRs can be identified through the use of Electron Backscatter Diffraction (EBSD) however doing so is costly and requires destruction of the metal component being tested. A new methodology of characterizing MTRs is needed to properly evaluate the reliability of engine components on live aircraft. The Air Force Research Lab Materials Directorate (AFRL/RX) proposed a solution of supplementing EBSD with two non-destructive modalities, Eddy Current Testing (ECT) and Scanning Acoustic Microscopy (SAM). Doing …

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Debris Survivability Study For Mega-Constellation Architectures, Joseph C. Canoy Mar 2023

Debris Survivability Study For Mega-Constellation Architectures, Joseph C. Canoy

Theses and Dissertations

The analysis for the overall theoretical debris survivabilty of mega-constellation architectures, with an emphasis on space-based ballistic missile defense constellation (SB-BMD), is explored via three extensive different Monte Carlo simulations: preliminary analysis of low Earth Orbit (LEO) mega-constellation survivabilty following a fragmentation event within the constellation, analysis of LEO mega-constellation survivability with a fragmentation event occurring on a satellite performing a maneuver to insert itself within the constellation, and the analysis of LEO mega-constellation survivabilty after a fragmentation event resulting from the destruction of a missile. The LEO mega-constellations represent the SB-BMD constellation. The first two analysis sections will include …

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Investigation Of Hypersonic Near-Wake Relaminarization Over A 7 Degree Half-Angle Cone, Jesse L. Roberts Mar 2023

Investigation Of Hypersonic Near-Wake Relaminarization Over A 7 Degree Half-Angle Cone, Jesse L. Roberts

Theses and Dissertations

To investigate the potential for relaminarization in the near-wake of a 7-degree half-angle cone, a series of hypersonic wake experiments were conducted in the Air Force Research Laboratory Mach 6.1 Ludwieg tube. Relaminarization is a spatial phenomenon that occurs when a turbulent flow reverts to a laminar-like state at a downstream location, where turbulent fluctuations negligibly contribute to average flow properties. Although relaminarization has been documented in subsonic and supersonic flows, the current body of knowledge related to the occurrence of, and mechanisms that drive, relaminarization at hypersonic speeds is sparse. Measurements were obtained across a range of freestream unit …

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Detonation Confinement In A Second-Generation Radial Rotating Engine, John T. Ursino Mar 2023

Detonation Confinement In A Second-Generation Radial Rotating Engine, John T. Ursino

Theses and Dissertations

In recent years, Rotating Detonation Engines (RDEs) have been coupled with turbomachinery to harness the benefits of detonative combustion. A novel type of RDE, referred to as the disk or Radial RDE (RRDE), has been developed in pursuit of length and weight savings compared to a traditional annular flow RDE. This design includes a disk-shaped device within which reactants flow from the outer radius, detonate, and exit the inner radius. In this paper several modifications have been made to a previously tested RRDE to address issues that arose with the original design. The combustion chamber diameter has been increased to …

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Development Of Novel Turbomachinery Manufacturing Methods, Timothy P. Winkler Mar 2023

Development Of Novel Turbomachinery Manufacturing Methods, Timothy P. Winkler

Theses and Dissertations

Compact turbine engines are of increasing interest as a means of propulsion for small, lightweight, low cost, unmanned aerial systems. This study looks to leverage advancements in novel manufacturing technology to produce turbomachinery components while simultaneously reducing costs and manufacturing time. To determine the feasibility of drop-in replacements for stock components this study focused on several research areas. This included materials research on both polymer-reinforced and ceramic materials, specimen tensile testing to determine temperature-dependent material properties, finite element analysis of multiple candidate materials, design and fabrication of a spin test rig, and physical spin testing of manufactured components to predict …

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Validation Of Bottom-Up Gnss Radio Occultation Method To Measure D- And E-Region Electron Density, Dylan J. Shaver Mar 2023

Validation Of Bottom-Up Gnss Radio Occultation Method To Measure D- And E-Region Electron Density, Dylan J. Shaver

Theses and Dissertations

An in-depth validation of a new bottom-up approach using GNSS Radio Occultation (GNSS-RO) data to generate electron density profiles in the D- and E-region ionosphere. This comparison was completed using daytime ionosonde profiles when sporadic-E (Es) was not present, and corresponding FIRI profiles. The average GNSS-RO profile is a few kilometers higher in altitude than the ionosonde profiles at the minimum frequency, f min. When the ionosonde profiles are shifted so that the altitudes match at f min, they are in good agreement up to the E-region peak altitude, hmE. Below f min, the …

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Simulation Of Neutron Generation From Laser-Driven Fusion In A Liquid D2o Sheet Using Novel Warpx Module, Colton R. Stoner Mar 2023

Simulation Of Neutron Generation From Laser-Driven Fusion In A Liquid D2o Sheet Using Novel Warpx Module, Colton R. Stoner

Theses and Dissertations

Using WarpX’s new nuclear fusion module, this work attempts to model an experimental system at the ELL at the AFIT with WarpX and draw conclusions about fusion products from resulting simulations. Recently, a table-top, high repetition rate, mixed radiation source was demonstrated at the ELL employing a HIL to fuse the deuterium nuclei present in a unique liquid target of heavy water. Analysis of the simulations predicted an isotropic output of neutrons from deuterium-deuterium fusion. These simulated neutrons were created in tens of femtoseconds from dense bodies of deuterons that were perturbed by the laser. However, it was found that …

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Automated Additive Layering Of Vat Polymerized Plastic Organic Scintillators, Chandler J. Moore Mar 2023

Automated Additive Layering Of Vat Polymerized Plastic Organic Scintillators, Chandler J. Moore

Theses and Dissertations

The current technology for fast neutron detection imaging is limited in achieving the required high spatial resolution, strong neutron discrimination, and practical time of manufacturing. Traditional fabrication methods require days of thermal polymerization and hundreds of man-hours to produce average resolution pixelated scintillator arrays. The present work helps to eliminate this limitation by developing an additive manufacturing technique to construct such detectors for use in in dual particle imaging applications. In this work, fast-, light-curing resins are used in a prototype automated assembly machine, capable of layering of individual light-cured resin layers and optical segmentation with a self-bonded specular reflector, …

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Pulsed Power Neutron Production With Deuterated Polymer Accelerator Targets, Anthony O. Hagey Mar 2023

Pulsed Power Neutron Production With Deuterated Polymer Accelerator Targets, Anthony O. Hagey

Theses and Dissertations

This document presents an investigation of the effect of deuterated polyethylene accelerator targets on the neutron fluence from a local mass injection dense plasma focus driven by the United States Naval Research Laboratory’s Hawk pulsed-power generator. After successful production of thin targets, the acquisition of thicker targets, and testing inside Hawk, it was found that the presence of a deuterated polyethylene target increased the neutron fluence. Results suggested that fluence can significantly increase with the presence of a deuterated target vs a nondeuterated target. Additive manufacturing printing was used as a production method in order to determine if deuterated accelerator …

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Fabrication And Testing Of A Novel Layered Metascintillator For Neutron And Gamma Discrimination, Evan W. Threlkeld Mar 2023

Fabrication And Testing Of A Novel Layered Metascintillator For Neutron And Gamma Discrimination, Evan W. Threlkeld

Theses and Dissertations

By leveraging new developments in fast-curing of plastic scintillators, it is possible to fabricate multi-material plastic scintillators, or metascintillators, which offer improved and/or novel capabilities for radiation detection. This document proposes one geometry of metascintillator that uses layers of green and blue scintillating material to discriminate neutron/gamma radiation, details the devices necessary to fabricate it, and analyzes the metascintillator’s response to radiation. A model of the metascintillator using Geant4 and Python suggested that spectral-based neutron/gamma event discrimination is possible with 63% of gamma events and only 1% of neutron events being multi-color. Fabrication of a 500 µm per layer metascintillator …

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The Electromagnetic Bayonet: Development Of A Scientific Computing Method For Aperture Antenna Optimization, Michael P. Ingold Mar 2023

The Electromagnetic Bayonet: Development Of A Scientific Computing Method For Aperture Antenna Optimization, Michael P. Ingold

Theses and Dissertations

The quiet zone of a radar range is the region over which a transmitted EM field approximates a uniform plane wave to within some finite error tolerance. Any target to be measured must physically fit within this quiet zone to prevent excess measurement error. Compact radar ranges offer significant operational advantages for performing RCS measurements but their quiet zone sizes are constrained by space limitations. In this work, a scientific computing approach is used to investigate whether equivalent-current transmitters can be designed that generate larger quiet zones than a conventional version at short range. A time-domain near-field solver, JefimenkoModels, was …

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Belief Space Planning For Alternative Navigation In Gnss-Denied Environments, Timothy I. Machin Mar 2023

Belief Space Planning For Alternative Navigation In Gnss-Denied Environments, Timothy I. Machin

Theses and Dissertations

Robust alternative navigation for autonomous agents becomes critical without reliable GNSS. Autonomous agents utilize measurement updates to constrain uncertainty. Belief space planning builds graph structures of beliefs within environments based on probable paths, agent and measurement models, and information of the environment. The Rapidly-exploring Random Alt-Nav Belief Graph (RRBANG) algorithm leverages stochastic filtering to implement a range of alt-nav measurement capabilities for robust navigation in GNSS-denied environments.

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Magnetic Anomaly Mapping For Navigation, Luke T. Bergeron Mar 2023

Magnetic Anomaly Mapping For Navigation, Luke T. Bergeron

Theses and Dissertations

Magnetic navigation (MagNav) has the potential to provide a global form of navigation that uses magnetic measurements of the Earth’s anomaly magnetic field and compares those measurements to a magnetic anomaly map in order to determine the user’s position. Widespread use of MagNav will require a database of fully-sampled, low-altitude magnetic anomaly maps. Existing magnetic anomaly map databases usually come from under- or poorly-sampled surveys. In this work, we provide an easy to follow MagNav anomaly map generation framework and set of survey collection metrics/requirements in an effort to help facilitate and standardize the creation of such a database. We …

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Detection And Identification Of Covert Devices Using Infrared And Stacked Optics Detection, Michael A. Reyneke Mar 2023

Detection And Identification Of Covert Devices Using Infrared And Stacked Optics Detection, Michael A. Reyneke

Theses and Dissertations

This work investigates stacked optics detection methodologies to successfully detect and identify observational systems with a cyber-physical sensing tool, ODIN (Observational Device Identification Network). ODIN successfully detected the presence of stacked optics and LiDAR systems using night-vision devices with a 96.32% average accuracy rating, both overt and covertly placed, with objective lens diameters ranging from 17 mm to 50 mm at distances between 1 m to 5 m with and without commonly employed anti-reflective countermeasures. ODIN provides a foundation for counter- measure capabilities of NIR devices and stacked optical systems in stationary environments. Additionally, a pilot study on smartphone LiDAR …

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Topological Variability In Water Distribution Networks, James M. Anderson Mar 2023

Topological Variability In Water Distribution Networks, James M. Anderson

Theses and Dissertations

Water distribution networks are critical infrastructure characterized by difficulties in their assessment and deteriorating performance due to aging components. Resilience analysis of networked infrastructure has replaced traditional risk analysis to focus on performance. Global Resilience Analysis can provide useful information to decision makers and system managers regarding repair and expansion of networks. Network performance has been found to be directly informed by network structure. This work leverages graph theory to assess network qualities that correlate with resiliency characteristics across 69 real world water networks. These networks are then grouped by their structural properties through k-means clustering and compared using parametric …

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Investigation Of Possible Alternatives To Fossil Fuels For The Dod In Indopacom, Terrence W. Caploe Mar 2023

Investigation Of Possible Alternatives To Fossil Fuels For The Dod In Indopacom, Terrence W. Caploe

Theses and Dissertations

Energy security, greenhouse gas (GHG) emissions, and geopolitical concerns in the south pacific require diversification and independence from legacy energy sources in the Indo-Pacific Combatant Command (INDOPACOM) area of operation (AO). The United States Government has placed mandates and directives to minimize the impacts of GHG on the climate. These orders require divestment from GHG producing fuel sources by 2050. This study compares the energy alternates to Jet Propulsion 8 (JP8) as Ammonia, Hydrogen, and Lithium-ion Batteries. The study uses Life Cycle Assessment (LCA) tools to determine the environmental impacts of various energy candidates in the South Pacific. These results …

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The Kinetics Of Biocontaminant Inactivation: A Comparative Study With Bacillus Globigii And Bacillus Anthracis, Leigh M. Durden Mar 2023

The Kinetics Of Biocontaminant Inactivation: A Comparative Study With Bacillus Globigii And Bacillus Anthracis, Leigh M. Durden

Theses and Dissertations

Bacillus anthracis has been a biological threat for decades and after the 2001 terrorist attack via the U.S. Postal Service where five people died, there was heightened awareness and inquiry on the subject (Goel, 2015; Greenberg et al., 2010; Nicholson & Galeano, 2003; Spotts Whitney et al., 2003). The health risk to humans makes this biological agent, a Tier 1 agent and one of the most likely to be used in an attack (Anthrax as a Bioterrorism Weapon | CDC, n.d.; Driks, 2009; Rose & Rice, 2014). B. anthracis is one of most resistant and potent biological warfare agents as …

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Civilian And Military Civil Engineer Mission In The Space Domain, Linda E. Kuster Mar 2023

Civilian And Military Civil Engineer Mission In The Space Domain, Linda E. Kuster

Theses and Dissertations

Military and civil interest in space-based operations has increased dramatically in recent years due to the discovery of life sustaining properties such as water on Mars and advancements in cyber technology. Civilian sector discussions and research have centered on the establishment of permanent extraterrestrial infrastructure, while discussions from the military perspective have focused on providing reliable, resilient infrastructure, capable of withstanding cyber-based and kinetic attacks. Both perspectives account for known threats and sustainment methods required to ensure success in the space domain. With the existence of threats for the military and civilian missions, civil engineers will undoubtedly be critical to …

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Illuminating The Unknown: A Mixed Methods Exploration Of The Dod Software Factory Ecosystem, Zachary O. Ryan Mar 2023

Illuminating The Unknown: A Mixed Methods Exploration Of The Dod Software Factory Ecosystem, Zachary O. Ryan

Theses and Dissertations

The Department of Defense’s (DoD) software factories are a collection of modern software acquisition programs that commonly employ the agile, network-based business strategies often found within commercial industries. Having been formally recognized by senior leaders for their revolutionary software development approaches, the software factories highlight a cultural shift within the DoD away from traditional organizational practices. As a result of the factories demonstrated successes, the number of programs employing non-traditional strategies is expanding. While this is notable, it also presents a challenge because a comprehensive understanding of the characteristics, structures, and behaviors of the DoD’s software factories does not currently …

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