Engineering Commons^™

Cost Estimating Relationships For Recurring T100 Flyaway Costs, Kyrie M. Rojo

Theses and Dissertations

This research investigates a dataset of over 80 Air Force and Navy aircraft and applies regression techniques to create two cost estimating relationships (CERs) for predicting recurring T100 flyaway costs, depending on where in the acquisition lifecycle the estimate takes place. The first CER explains 89 percent of the variation in the dataset and can be applied prior to Milestone B (MS B). The second CER explains 88 percent of the variation in the dataset and can be applied between MS B and MS C. Significant cost drivers identified include stealth, cohort, empty weight, the natural log of speed, legacy …

Net Zero Water Air Force Installations, Kenneth R. Mcknight

Theses and Dissertations

The United States continues to face problems of a reduction in quality and quantity of groundwater sources because water extraction exceeds natural source recharge. The Air Force has recognized the importance of these groundwater sources but has put minimal effort into determining their contribution to the depletion of these sources. The purpose of this study is to determine this contribution by determining whether Air Force installations are net zero water. This is done using a geospatial information system to determine the volume of water recharging groundwater sources associated with an Air Force installation. This volume is then compared to the …

Defense Industrial Base Mergers And Acquisitions In The Post-Cold War Era, Corey D. Mack

Theses and Dissertations

The United States Department of Defense (DoD) relies on prime contractors for weapon system development, acquisition, and sustainability, but the increased consolidation of the Defense Industrial Base (DIB) through mergers and acquisitions (M&A) has raised concerns over reduced competition. This research consists of two studies. The first reviews existing literature to identify factors behind the DIB's increased M&A activity since the 1990s, such as DoD budget cuts and market structure. The second study examines the relationship between a prime contractor's financial health and M&A spending, finding a significant relationship between efficiency and M&A spending. Policymakers can use this information to …

Prediction Of Persistent Post-Traumatic Headache With Long Short-Term Memory Networks, Todd C. Campo

Theses and Dissertations

Military members in combat situations are at a high risk for experiencing a Traumatic Brain Injury (TBI), often leaving them with Post-Traumatic Headache (PTH). There is currently a poor understanding of what factors predict if a patient will endure acute (short-term) PTH or Persistent PTH (PPTH). The Concussion Assessment, Research, and Education (CARE) Consortium dataset contains a variety of pre-and-post-injury concussion assessments taken by NCAA athletes and service academy cadets between 2014 and 2018. Participants in this study (n = 1769) suffered a TBI. Using this longitudinal data, three models were constructed: an LSTM model using the raw assessment scores, …

Material Property Dependence Of Nanoparticle Silicon Carbide Alloying In Additively Manufactured Molybdenum, Andrew P. Mason

Theses and Dissertations

The structural performance of additively manufactured Mo printed by LPBF can be significantly improved by nanoparticle alloying. Previous AFIT studies of SiC nanoparticle addition conducted by Ellsworth (2022) et al. demonstrated increased powder consolidation, leading to reduced porosity, increased microhardness, and a shift in atomic defect concentrations. The addition of defected SiC particles is proposed to reduce in situ oxidation by acting as a sacrificial oxidizing agent and contributing to the formation of Mo disilicide secondary phases. This study investigated the relationship between laser powder bed fusion Mo microscale and nanoscale properties with varying SiC particle size while maintaining a …

Towards An Understanding Of The Thermodynamic Properties Of Crtao4: A Computational Perspective, Tanner B. Gordon

Theses and Dissertations

Materials that can withstand higher temperatures are paramount for next-generation aircraft design. Hypersonic capabilities and jet-turbine engines operate in extreme environments. Choosing materials that have high thermal stability and oxidation resistance for these applications can increase engine efficiency, reduce size, weight and power (SWaP), and increase the maneuverability of the aircraft. The mixed oxide CrTaO₄ has been experimentally observed to significantly contribute to oxidation resistance at high temperatures. However, and despite its significance, its properties remain largely unknown. This work explores the thermal properties of this material from a multi-scale approach, by obtaining an accurate description of the thermodynamics …

Fast Engineering Model For Defect Production In Magnesium Oxide, Henry R. Little

Theses and Dissertations

Defect production from irradiation of materials with thicknesses much less than the mean free path for neutron interaction is explored. A model is developed using the Monte Carlo N-Particle transport code from Los Alamos National Laboratory, experimental data from irradiations at the Oak Ridge High Flux Isotope Reactor, defect production theory, and atomistic simulation results to predict the total number of F-centers resulting from neutron irradiation of a MgO rod. This model accurately predicts the concentration of atomic defects under conditions closely matching experiments at long timescales, for large geometries, and requiring only 6.9 minutes on a single CPU. Results …

Information System Availability Status And Its Impact On Customer Wait Times, Joshua A. Cramer

Theses and Dissertations

The Military Personnel Flight relies on Air Force Information Systems, specifically the Defense Enrollment Eligibility and Reporting System (DEERS), to manage the personnel records. When DEERS experiences a failure, then the operational ability of the Military Personnel Flight is affected. This study aims at identifying the impact Air Force information system’s availability status has on customer wait times using linear regression.

Fragility Of The Florida Panhandle's Electrical Transmission Grid To Hurricanes, Zachary D. Schumann

Theses and Dissertations

The increased frequency and intensity of extreme weather events from climate change necessitates understanding impacts on critical infrastructure, particularly electrical transmission grids. One of the foundational concepts of a grid’s resilience is its robustness to extreme weather events, such as hurricanes. Resilience of the electric grid to high wind speeds is predicated upon the location and physical characteristics of the system components. Previous modeling assessments of electric grid failure were done at the systems level with assumptions on location and type of specific components. To facilitate more explicit adaptation metrics, accurate component-level information is needed. In this study, we build …

The U.S. Army Officer-To-Unit Assignment Problem, Andrea L. Phillips

Theses and Dissertations

Every two to three years, U.S. Army officers must change duty stations, which entails a selection process based on preferences. Currently, officers are assigned to units using a stable-marriage algorithm. Two impracticalities occur within this process. First, officers are required to submit strictly ranked preferences, not allowing indifference among units. Second, the stable-marriage algorithm does not give flexibility to alternative priorities. This research focuses on two modifications to the current model. First, a mixed integer program is created that allows the user, U.S. Army Human Resources Command, to consider other priorities: unit preferences and maximum officer disappointment. Second, generated data …

An Approximate Dynamic Programming Approach For Solving An Air Combat Maneuvering Problem With Directed Energy Weapons, Elisha A. Palm

Theses and Dissertations

Performing within visual range (WVR) air combat involves the execution of complex air maneuvers and rapid sequential decision making. The complexity of these decisions can increase even further when including additional weapon capabilities. The advancement of unmanned autonomous vehicle technology and weapon capabilities can help combat the hindrance that comes with human limitations. Autonomous unmanned combat aerial vehicles (AUCAVs) and the implementation of advanced weapon capabilities such as Directed Energy Weapons (DEWs) can prove to be vital in a WVR air combat context. This derives the question – Can AUCAV’s possess the proper artificial intelligence and weapon capabilities to attain …

Bayesian Recurrent Neural Networks For Real Time Object Detection, Stephen Z. Kimatian

Theses and Dissertations

Neural networks have become increasingly popular in real time object detection algorithms. A major concern with these algorithms is their ability to quantify their own uncertainty, leading to many high profile failures. This research proposes three novel real time detection algorithms. The first of leveraging Bayesian convolutional neural layers producing a predictive distribution, the second leveraging predictions from previous frames, and the third model combining these two techniques together. These augmentations seek to mitigate the calibration problem of modern detection algorithms. These three models are compared to the state of the art YOLO architecture; with the strongest contending model achieving …

Designing A Counter-Iads Drone Swarm: Using Evolution To Evaluate Combat Assumptions Underpinning Drone Swarm Target Assignment, Olin H. Kennedy

Theses and Dissertations

The original research goal was to combine the best techniques in the drone swarm literature and model a functional combat drone swarm that conducts a Suppression of Enemy Air Defense (SEAD) mission. However, the body of literature regarding Drone Swarm Target Assignment (DSTA) does not model enemy counteraction and assumes that the drones’ targets are compliant against destruction. Therefore, a model of enemy counteraction against drone swarms is developed, and Novel DSTA (NDSTA) is proposed to respond to the weaknesses of the current DSTA. Both methods of target assignment are combined with a tunable trajectory generation model, and the performance …

Simulation And Analysis Of Dynamic Threat Avoidance Routing In An Anti-Access Area Denial (A2ad) Environment, Dante C. Reid

Theses and Dissertations

This research modeled and analyzed the effectiveness of different routing algorithms for penetration assets in an A2AD environment. AFSIM was used with different configurations of SAMs locations and numbers to compare the performance of AFSIM’s internal zone and shrink algorithm routers with a Dijkstra algorithm router. Route performance was analyzed through computational and operational metrics, including computational complexity, run-time, mission survivability, and simulation duration. This research also analyzed the impact of the penetration asset’s ingress altitude on those factors. Additionally, an excursion was conducted to analyze the Dijkstra algorithm router’s grid density holding altitude constant to understand its impact on …

Overall Effectiveness Superposition Theory For A Film Cooled Leading Edge, Bailey W. Hopkins

Theses and Dissertations

Film cooling experimentation traditionally reports on the cooling performance of specialty-crafted cooling holes at various angles and array patterns. This is repeated across a variety of model geometries in an effort to provide as much information to the turbine blade designer. While this extensive database of cooling performance is helpful, its true value is found in the designer’s ability to effectively superpose the results on top of each other. One technique for predicting the performance of multiple coolant sources is film cooling superposition theory. This analytical model was employed classically by characterizing the adiabatic effectiveness across a model’s surface; however, …

Analysis And Optimization Of Contract Data Schema, Franklin Sun

Theses and Dissertations

agement, development, and growth of U.S Air Force assets demand extensive organizational communication and structuring. These interactions yield substantial amounts of contracting and administrative information. Over 4 million such contracts as a means towards obtaining valuable insights on Department of Defense resource usage. This set of contracting data is largely not optimized for backend service in an analytics environment. To this end, the following research evaluates the efficiency and performance of various data structuring methods. Evaluated designs include a baseline unstructured schema, a Data Mart schema, and a snowflake schema. Overall design success metrics include ease of use by end …

Advancing Autonomous Swarm Behavior In A Simulated Anti-Access Area Denial (A2ad) Environment, Chad P. Macwilkinson

Theses and Dissertations

Advancements in modern IADS have bolstered A2AD environments and subsequently degraded the advantages that the Air Force once held, prompting a call to reform the nature of warfare in order to challenge these threats. A solution is weapon swarming technology, which has the ability to overwhelm IADS by engagement of a large numbers of low-cost, but lethal air assets that have autonomous functionalities. This research proposes the application of a four dimensional framework for autonomy to a swarm of cruise missiles. A virtual A2AD environment of two opposing forces is constructed using the AFSIM, wherein a manned bomber seeks to …

Shock Induced Trailing Edge Separation Effect On F-16 Limit-Cycle Oscillation, Eric D. Stubblefield

Theses and Dissertations

No abstract provided.

Characterizing Jet Interaction Effects On A Cone In Mach 3.9 Flow, Titus J. Lee

Theses and Dissertations

Although jet interaction in the context of attitude control for aircraft and air weapons have been investigated for a variety of conditions and geometries, the knowledge base for their use with hypersonic vehicles is far more limited. The objective of the present investigation is to characterize the jet interaction effects in a Mach 3.9 freestream in the AFIT Small Supersonic Wind Tunnel using schlieren flow visualization and a 6-degree of freedom balance. A 7° aluminum cone was attached to the balance while air was injected through a stainless-steel tube, which was separately supported without any contact with the cone body …

Optimal Control Of Precision Airdrop Trajectories Using Direct Collocation And Analytical Methods, Edward J. Maxwell

Theses and Dissertations

The work herein investigates the preliminary designs of an optimal navigation controller for a scalable cylindrical airdrop system controlled with grid fins in planar motion. Precision airdrop capabilities are desired for a range of military and humanitarian missions. Fielded airdrop systems have not met desired performance objectives, particularly regarding accuracy. Direct collocation and analytical methods were utilized to solve the optimal control problem for the grid fin controlled precision airdrop system examined in this work. The optimal control problem was comprised of two phases: controlled descent and parachute descent. Minimum and maximum ranges for the system under varying wind fields …

Deeptype: A Deep Neural Network Approach To Keyboard-Free Typing, Joshua V. Broekhuijsen

Theses and Dissertations

Textual data entry is an increasingly-important part of Human-Computer Interaction (HCI), but there is room for improvement in this domain. First, the keyboard -- a foundational text-entry device -- presents ergonomic challenges in terms of comfort and accuracy for even well-trained typists. Second, touch-screen smartphones -- some of the most ubiquitous mobile devices -- lack the physical space required to implement a full-size physical keyboard, and settle for a reduced input that can be slow and inaccurate. This thesis proposes and examines "DeepType" to begin addressing both of these problems in the form of a fully-virtual keyboard, realized through a …

Implications Of Good Faith In Construction Contracts, Nadine Rashed

Theses and Dissertations

The principle of good faith is making inroads and continues to significantly impact various contractual arrangements. In most civil legal systems, good faith is present as a core principle. Nevertheless, its definition is beyond doubt scarce in the construction industry. However, the common law lacks the good faith obligations. Good faith is one of the fundamental principles that impact the contractual obligations between the contracting parties. This paper creates an urge to address the implications of good faith on construction contracts in the pre-contract and post-contract award stages. Therefore, the paper’s objective is to propose a legal/contractual clause that meets …

Chemical Vapor Deposition Grown Monolayer Graphene Microsensors With Rf Ring Oscillator Backend Circuit, Mohamed Ahmed Waheed Tawfik

Theses and Dissertations

This work presents the integration of a backend RF ring oscillator readout circuit to transduce structural changes in CVD-grown monolayer graphene into an electrical signal and the implementation of it to detect physical changes such as radiation and flexural strain. The novelty in this work lies in the following (1) the ability of the sensor platform to overcome environmental effects, such as light photons and temperature changes, through the readout circuit, and (2) it opens the door for the scalability of CVD-grown graphene-based for sensors and devices. Thus, the introduced sensors solve several downsides in the state-of-the-art graphene-based radiation and …

Influence Of Processed Natural Black Sand Vs. Natural White Sand And Silica Flour As Additives To Oil-Well Cementing Applications, Ramy Abuel Maaty

Theses and Dissertations

Cementing is a crucial and fundamental step in the process of drilling wells to extract oil from its reservoirs. Cementing main functions are to achieve zonal isolation and provide mechanical support to the casing. Impermeable and powerful cement is strongly desired to withstand high pressures and temperatures during the lifetime of the producing wells. Various additives to cement, such as silica flour, fly ash, Nano-additives and other advanced materials have been used and tested to attain improved cement of higher quality and enhanced properties such as permeability, porosity, mechanical and rheological properties. Very few researches have discussed the uses of …

Biogas Combustion Characteristics In A Concentric Flow Slot Burner: Effects Of Co2 Concentration On Stability And Flame Structure, Maged Kiriakos

Theses and Dissertations

Biogas combustion is affected by the concentration of carbon dioxide. The successful applications of Biogas as a sustainable renewable alternative fuel produced from waste depend on its combustion stability, heat release, and pollution level. The aim of the current study is to apply new combustion technology and study the stability and combustion characteristics of natural gas with different percentages of carbon dioxide from 0 to 40% simulating biogas fuel. The stability characteristics and the temperature profiles of turbulent planar flames at different levels mixture inhomogeneity are investigated and presented in this work. The flames are created in a newly developed …

Accurate Evaluation Of The Direction-Dependent Mechanical Properties Of Ideal Single Crystals: A Comparative Ab Initio Study, Jaylan Ali Elhalawani

Theses and Dissertations

The mechanical properties of a single crystal or a grain in a polycrystalline material are highly dependent on the direction of the applied load. Key properties of interest are the Young’s modulus and the Poisson ratio in the small strain limit, and the ideal tensile strength in the large strain regime. Prior atomistic computations of these properties interchangeably used two approaches. In one approach the stress-strain response is explicitly calculated via a numerical tensile test experiment. In the second approach the second order single crystal elastic constants are computed via small deformations and then used in analytical equations to derive …

Vr-Based Safety Training Program For High-Rise Building Construction, Sahar Badr

Theses and Dissertations

The rates of fatal and non-fatal accidents within the construction industry across the globe are surging despite the massive efforts that are being exerted toward maintaining a safe working environment. Past research has proved that the provision of effective safety training programs is a primary course of action that should be taken to minimize construction accidents, fatalities, and both fatal and nonfatal injuries.

However, in acknowledging the limitations of traditional safety training programs within the construction industry, several researchers have addressed the urge to incorporate novel training practices that are based on the modern virtual reality (VR) technology to promote …

Enhancing Performance Of Gravity Driven Membranes For Water Purification In Small Rural Communities, Amr Ezzat Melligy Mr.

Theses and Dissertations

Due to the rapid population growth in Egypt, providing safe drinking water is becoming an ongoing challenge especially in rural scattered communities. It became more crucial than ever to find innovative and affordable solutions to purify water and reduce water-borne diseases. Ultrafiltration and micro-filtration membranes has been successful in large, centralized plants and is currently one of the popular solutions to provide high quality product water. However, using those membrane systems in rural areas is challenged by several parameters; among which are; the absence of skilled workers, stable energy sources and availability of chemicals. The goal of this thesis is …

Development Of The Tlvmie Force Field And A Standardized Methodology For Improved Pure-Component And Mixture Liquid Viscosity Predictions, Daniel J. Carlson

Theses and Dissertations

Existing viscosity prediction methods and relevant literature are reviewed. An exhaustive review of group contribution, corresponding states, and interpolative prediction methods finds that even the best of these models produces large prediction errors and often require significant experimental data. Molecular dynamics simulation techniques for viscosity prediction are evaluated and compared to one another to determine the best choice for this work. A thorough investigation finds that Equilibrium Molecular Dynamics (EMD) simulations are the best option for reproducible and reliable liquid viscosity predictions. The many tuning parameters available in molecular dynamics simulations are investigated for their effects on prediction uncertainty and …

Formulation Of Encapsulated Nanoparticles Of Leek Extract As Antimicrobial And Anticancer Agent, Rawan Hassan Mohamed Elghanam

Theses and Dissertations

Leek extract (LEK) has broad therapeutic activity. However, plant extract use has many drawbacks, which could be resolved using nanocarriers. The purpose of this research work was to prepare chitosan nanoparticles (CS NPs) encapsulating LEK and investigate their antioxidant, antimicrobial, and anticancer activity. Gas chromatography-mass spectroscopy was used to determine the LEK components. The CS-LEK NPs were produced by tripolyphosphate (TPP) crosslinking with chitosan (CS) the ionic gelation methodology. The particle size was 331 nm, zeta potential (ZP) was 28.9 mv, polydispersity index (PDI) was 0.4, encapsulation efficiency (EE) was 65.6%, and loading capacity (LC) was 28.8 % of the …