Engineering Commons^™

Resilient Maintenance Infrastructure: Dynamic Repair Network Designs To Effectively Manage Supply Chain Disruptions, David W. Wallace Iii

Theses and Dissertations

Supply chains are facing numerous changes contributing to their increase in complexity and vulnerability to disruptions. Subsequently, decision-makers lack a transparent, generalizable tool to quantify supply chain resilience and assess additional resilience investments. This research facilitates a more profound understanding of the intricacies and interrelation of supply chain nodes and constructs. It integrates the Area under the Curve (AUC) metric to quantify performance or any organizational measure of competitive advantage amid a disruption. Due to its structural resemblance to various organizational platforms, the subset United States Air Force (USAF) F-16 engine repair and supply network is modeled employing discrete-event simulation. …

A Simulation Modeling The Effects Of Maintenance Personnel On Aircraft Sortie Generation, Benjamin D. Huffman

Theses and Dissertations

Commanders and wargamers lack adequate tools to quickly determine the number of mission-capable (MC) aircraft and number of achievable sorties to support wargames and exercises. Even less understood is the impact of available maintenance personnel on sortie generation. The Expected-Number-of-In-Game-Mission-capable Aircraft (ENIGMA) simulation was recently developed to calculate the number of MC aircraft and number of sorties own accounting for the number and type of aircraft, scheduled sorties, mean-time-between-failure (MTBF), and mean-time-to-repair (MTTR). ENIGMA is extended by replacing the MTTR input with functions derived from actual numbers and types of maintenance personnel available. Functions in the form of response surface …

Static Fatigue Of Hi-Nicalon™ S Ceramic Fiber Tows At 600°C In Air And Silicic Acid-Saturated Steam, Caleigh M. Nelson

Theses and Dissertations

Ceramic matrix composites (CMCs) have the potential to be utilized in applications such as hypersonic vehicles, aircraft leading edges, hot sections of engines, and rocket nozzles. Of particular interest are advanced SiC/SiC composites that can withstand the elevated temperatures and harsh oxidizing environments while maintaining their properties and structural integrity under an applied load. Steam, a major component of combustion environment, is one such aggressive oxidizing environment. As steam passes through the SiC/SiC composite, entering the composite interior through the cracks in the SiC matrix, it becomes saturated with silicic acid, Si(OH)₄. Before incorporating SiC/SiC composites in the …

An Analysis Of Application Type, Super Domain, And Productivity In Software Intensive Defense Acquisition, Evan P. Amato

Theses and Dissertations

The productivity of software developers has been an area of interest in the private industry in an endeavor to more appropriately interpret pertinent software development cost drivers. In an effort to better predict the cost of developing software, many have focused on Application Type as an important factor. The Department of Defense (DoD) has recently adopted a similar focus. Studies on categorization schemes of Application Types have shown increasingly relevant cost and productivity driving characteristics recently in the DoD. Identification of factors associated with distinct productivity effects is important for the defense acquisition and software cost estimation domains. Distinct factors …

Optimal Defense Of High Value Airborne Assets, Isaac E. Weintraub

Theses and Dissertations

Optimal control theory and differential game theory is applied to the study of the defense of high value airborne assets, particularly in the case of a single threat such as an adversarial aircraft or missile. Rather than utilizing onboard defenses of the high value airborne asset, defense is proposed using a teamed unmanned combat air vehicle. The common scenario throughout this dissertation involves the defense of a high value airborne asset (evader) teamed with an unmanned combat vehicle (defender) against a single threat (pursuer). The unmanned combat air vehicle (defender), provides defense in one of two ways: kinetic or directed …

A Framework For Autonomous Cooperative Optimal Assignment And Control Of Satellite Formations, Devin E. Saunders

Theses and Dissertations

A decentralized, cooperative multi-agent optimal control framework is presented to offer a solution to the assignment and control problems associated with performing multi-agent tasks in a proximity operations environment. However, the framework developed may be applied to a variety domains such as air, space, and sea. The solution presented takes advantage of a second price auction assignment algorithm to optimally task each satellite, while model predictive control is implemented to control the agents optimally while adhering to safety and mission constraints. The solution is compared to a pseudospectral collocation method, and a study on tuning parameters is included.

Deep Reinforcement Learning Applied To Spacecraft Attitude Control And Moment Of Inertia Estimation Via Recurrent Neural Networks, Nathaniel A. Enders

Theses and Dissertations

This study investigated two distinct problems related to unknown spacecraft inertia. The first problem explored the use of a recurrent neural network to estimate spacecraft moments of inertia using angular velocity measurements. Initial results showed that, for the configuration examined, the neural network can estimate the moments of inertia when there is a known external torque. The second problem trained a reinforcement learning agent, via proximal policy optimization, to control the attitude of a spacecraft. The results demonstrated that reinforcement learning may be a viable option for guidance and control solutions where the spacecraft model may be unknown. The trained …

Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite For Aerospace Systems, Benjamin C. Lam

Theses and Dissertations

Carbon nanotubes (CNTs) exhibit outstanding mechanical properties, such as exceptionally high tensile stiffness and strength, combined with excellent electrical and thermal characteristics. This research investigates the mechanical properties and performance of a newly developed hybrid nano-engineered composite. The carbon fiber/polymer matrix composite incorporates a forest of vertically aligned CNTs, called NanoStitch, between the prepreg plies. Basic tensile properties of both material systems were investigated for both on-axis [0/90] and off-axis [±45] fiber orientations at room temperature. Tension-tension fatigue tests were performed with a frequency of 1.0 Hz and a ratio of minimum stress to maximum stress of R= 0.05. Fatigue …

Density Measurements Of Neutral Xenon Using Multiphoton Ionization And Microwave Spectroscopy In A Hall Effect Thruster, Taylor J. Foy

Theses and Dissertations

A new dye laser and microwave scattering system for measuring low speed xenon particles was installed to characterize a commercially sourced 600 W Hall effect thruster. The new system uses multiphoton ionization and microwave spectroscopy to determine number density and velocity measurements of neutral xenon atoms in the plume of a Hall thruster. A study was conducted to ensure the new system will be able to accurately measure these neutrals in future work. The ultimate goal of this new system is to isolate and characterize the extra thrust produced in Hall Effect Thrusters due to finite volume vacuum chambers.

Fatigue Of Two Oxide/Oxide Ceramic Matrix Composites At 1200°C In Air And In Steam. Effect Of Diamond Drilled Effusion Holes, Anthony R. Cabri

Theses and Dissertations

The tension-tension fatigue behavior of two oxide-oxide ceramic matrix composites (CMCs) was investigated at 1200°C in laboratory air and steam. Both composites consist of a porous oxide matrix reinforced with laminated, woven mullite/alumina (NextelTM720) fibers. The first composite had an alumina matrix, while the second had an alumina-mullite matrix. First, we assessed the effects of incorporating mullite into the matrix material on fatigue performance by studying the tension-tension fatigue behavior of alumina-mullite matrix CMC. Second, we evaluated the effects of effusion holes on the alumina matrix CMC's fatigue performance. Specimens containing an array of 17 effusion holes of 0.5-mm diameter …

Gps-Denied Localization Of Daughter-Ships In A Mother-Daughter Ship Collaborative Environment, Ethan W. Jacquin

Theses and Dissertations

This research investigates the possibility of using the communication link between a mothership and daughter-ship UAV and an Extended Kalman Filter algorithm as a replacement of GPS, assuming a ranging link exists between the mothership and daughter-ship and that the mothership is GPS-enabled. A simulation study examines the viability of the approach and the effect of parameters such as distance, altitude, roll angle, speed, ranging sensor noise, and inertial measurement unit uncertainty were considered. The magnitude of the errors between predicted and measured position were examined and a range of acceptable flight parameters was formed.

Charge Mitigation Technologies For Aircraft Platforms, Mitchell L. Rudy

Theses and Dissertations

Research into ion-based advanced propulsion systems, such as air-breathing Hall effect thrusters on high-velocity aircraft and ion-propelled thrusters on spacecraft, necessitates addressing accompanying residual electric charge accumulation on the ungrounded flight platform. An experimental testbed was constructed to assess charge mitigation technologies and their effectiveness on aircraft. A Van de Graaff generator provided static charge accumulation levels exceeding a megavolt when combined with a high voltage direct current source generator. This research attached an isolated airfoil structure to the Van de Graaff generator's lower terminal to measure the induced leakage current under various applied environmental conditions, including up to three …

Evaluation Of Efficient Water Reuse Technologies For Sustainable Forward Operating Bases, Kelsie L. Crouch

Theses and Dissertations

A secure water source is essential to the resiliency and readiness of military installations and contingency operation locations, especially those located in the dry climates the US military operates in today. There are multiple issues of concern when identifying water sources, such as security, cleanliness, accessibility, and sustainability. Water resources pose a potential vulnerability to mission readiness in a remote, agile environment, such as a forward operating base (FOB). Having a secure water resource helps facilitate mission readiness in the contingency environment, offering the opportunity to be more resilient and cost-effective. Current water treatment technologies present the possibility to perform …

Conversion From Coal To Natural Gas At Wright Patterson Air Force Base: An Analysis And Case Study, Tyler A. Ferry

Theses and Dissertations

Over the last 20 years, natural gas has replaced coal as the preferred fossil fuel for heat and power generation across the United States, due to its increased prevalence, lower cost, and reduced environmental impacts. While most conversion decisions are driven by cost savings, proponents of energy transitions often cite emissions reductions as a tangential benefit. Over the same time, climate change and its impact on the environment and society have come to the forefront of scientific inquiry. One example of the transition from coal to natural gas can be found in Dayton, Ohio. Wright Patterson Air Force Base (WPAFB) …

Examining How Standby Assets Impact Optimal Dispatching Decisions Within A Military Medical Evacuation System Via A Markov Decision Process Model, Kylie Wooten

Theses and Dissertations

The Army medical evacuation (MEDEVAC) system ensures proper medical treatment is readily available to wounded soldiers on the battlefield. The objective of this research is to determine which MEDEVAC unit to task to an incoming 9-line MEDEVAC request and where to station a single standby unit to maximize patient survivability. A discounted, infinite-horizon continuous-time Markov decision process model is formulated to examine this problem. We design, develop, and test an approximate dynamic programming (ADP) technique that leverages a least squares policy evaluation value function approximation scheme within an approximate policy iteration algorithmic framework to solve practical-sized problem instances. A computational …

An Analysis Of Stability In Software Resources Data Report (Srdr) Computer Software Configuration (Csci), Trevor J. Violette

Theses and Dissertations

This research studies cost and schedule stability in programs that utilize Software Resource Data Report (SRDR) reporting standards. We find software programs at the Computer Software Configuration Item (CSCI) level show much lower levels of stability than previously published DoD stability research that focused on aircraft. A comparison of software development methods found little to no difference between Agile and Plan Driven methodologies. Critical Success Factors (CSF) were identified from prior literature and used to examine CSCIs from the SRDR dataset. Focusing on schedule or cost resulted in different variables showing significance. A CSCI is more likely to remain on …

Computational Electromagnetic Modeling Of Metasurface Optical Devices With Defect Study, Carlos D. Diaz

Theses and Dissertations

One of the first fabricated metasurface optical devices, the in-plane V-antenna lenses, were plagued by a fundamental transmission limit (<25 >). Two distinct sets of Out-of-Plane phase elements were designed with improved transmission (~60 ). These were fabricated as beamsteerers and characterized in terms of their Bidirectional Transmittance Distribution Function measured as a function of scatter angle. Experimental data from the beamsteerers was analyzed via simulations using a finite element method (FEM). The measurements showed the designed beamsteering, but also a strong zero-order diffraction not present in the simulations, which motivated this study to understand what was causing these differences. …

Sensors For The Detection Of Ammonia As A Potential Biomarker For Health Screening, Peter P. Ricci, Otto J. Gregory

Chemical, Biomolecular, and Materials Engineering Faculty Publications

The presence of ammonia within the body has long been linked to complications stemming from the liver, kidneys, and stomach. These complications can be the result of serious conditions such as chronic kidney disease (CKD), peptic ulcers, and recently COVID-19. Limited liver and kidney function leads to increased blood urea nitrogen (BUN) within the body resulting in elevated levels of ammonia in the mouth, nose, and skin. Similarly, peptic ulcers, commonly from H. pylori, result in ammonia production from urea within the stomach. The presence of these biomarkers enables a potential screening protocol to be considered for frequent, non-invasive …

Spatio-Temporal Data Mining For Aviation Delay Prediction, Kai Zhang, Houbing Song, Yushan Jiang, Dahai Liu

Publications

To accommodate the unprecedented increase of commercial airlines over the next ten years, the Next Generation Air Transportation System (NextGen) has been implemented in the USA that records large-scale Air Traffic Management (ATM) data to make air travel safer, more efficient, and more economical. A key role of collaborative decision making for air traffic scheduling and airspace resource management is the accurate prediction of flight delay. There has been a lot of attempts to apply data-driven methods such as machine learning to forecast flight delay situation using air traffic data of departures and arrivals. However, most of them omit en-route …

How New, Innovative Technology Can Be Implemented To Combat The Construction Industry Labor Shortage, Noah David Jackson

The Professional Constructor

This essay addresses the construction industry’s need to compensate for the current and projected labor shortage through innovative technologies. In the first portion of this essay, three technologies that are most feasible for implementation – the Internet of Things (IoT), Drones, and Prefabrication – are detailed. The challenges faced are then discussed before the second major portion in which steps for implementation are outlined. These steps include forming partnerships, learning the process, communicating, training, implementing, and adapting and improving. The essay concludes with a discussion of how the AGC organization, and members within, can aid the industry in meeting this …

The Adaptative Construction Industry, Rhett Cox

The Professional Constructor

The construction industry is an industry that always unites to find ways to solve problems. It is very complex and requires considerable organization, hard work, specific skills, and a whole lot of determination. In this paper, I will discuss three ways that the industry is making strides to make construction better and more efficient: (a) increased use of modular construction and prefabrication, (b) use of drones, and (c) Building Information Modeling (BIM) use. With the construction process becoming more and more complex, improving efficiency and safety has gained more attraction, especially when coping with fundamental issues such as labor shortage, …

How New, Innovative Technology And Project Execution Tools And Techniques Can Be Used To Improve The Construction Process (Including Safety And Efficiency), James L. Craig

The Professional Constructor

Humanity has often sought to utilize tools and technology to make working faster, more efficient, more comfortable, and more accurate. While humans may have started with stone tools, we have since developed complex and sophisticated mechanical and digital technologies. The construction industry has been utilizing construction technology and equipment for these same reasons for generations. While other industries have embraced the use of smart, autonomous technology and robotics, the construction industry has steadily fallen behind in this effort. In this paper, I will discuss current work using these tools and possible applications for future development.

The Impact Of Climate Change On Building Energy Demands And Mitigation Measures In Florida, Aiyin (Erin) Jiang

The Professional Constructor

Tropical and subtropical parts of the world are projected to be the most vulnerable to the impact of climate change on building energy consumption demand. Few studies, however, focus on all four greenhouse emission scenarios defined by International Panel of Climate Change, which would be useful in assessing the energy demand challenges areas such as Florida. This study applies the most recognized climate change model downscaling approach, the morphing method, to investigate the impact of climate change on the commonly used commercial buildings in Florida’s climate zones under all four emission scenarios. It also analyzes the efficacy of various mitigation …

Frequency And Magnitude Of Cost Growth In Public Works Contracts, George Fulton, Panagiotis Mitropoulos

The Professional Constructor

Cost overruns are a persistent issue in the construction industry. This paper investigates factors that may drive cost growth on public works contracts. The study collected data on 1,043 public works projects completed over a three year period. The analysis examined the impact of four factors on cost overruns: (1) Project type, (2) Contract size, (3) Contract duration, and (4) Construction placement (value per day). The data were analyzed using a combination of basic descriptive statistics along with statistical hypothesis testing of means for various factors affecting cost growth. Cost growth was found to vary significantly by project type, contract …

Case Study Of Real-World Emissions Rates Verus Epaemission Standards For Motor Graders, Boshra Karimi, Phil Lewis

The Professional Constructor

Using the Volkswagen emissions scandal as motivation, the purpose of this case study was to investigate whether or not heavy-duty diesel construction equipment exceeds EPA emissions standards for nonroad diesel engines. The equipment analyzed included four separate motor graders with EPA emissions standards Tier 0, Tier 1, Tier 2, and Tier 3 engines. The analysis was based on a dataset of real-world emissions rates collected from in-use equipment on actual jobsites. The results showed that mass per time emissions rates for hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matter decreased as the EPA emissions standards became more stringent. Furthermore, there …

Understanding Sub-Contractor Selection Factors In Thebuilding Construction Industry For The Southeastern United States, Dhaval Gajjar, Cayla Anderson

The Professional Constructor

The primary entities within building construction industry consists of the owner, the architect / engineer, and the general contractor, that ensure the success of any construction project. On a traditional project, the owner selects and contracts with the general contractor to construct a building designed by the architect. A considerable amount of research has been conducted to understand the owner’s selection factors to hire a qualified general contractor. However, the general contractor selected for the project seldom self-performs the entire construction of a building. The general contractor might self-perform some aspects of the actual building construction, but they will typically …

Condition Monitoring And Fault Detection Of Blade Damage In Small Wind Turbines Using Time-Series And Frequency Analyses, Luke H. Costello

Master's Theses

Condition monitoring systems are critical for autonomous detection of damage when operating remote wind turbines. These systems continually monitor the turbine’s operating parameters and detect damage before the turbine fails. Although common in utility-scale turbines, these systems are mostly undeveloped in distributed, small-scale turbines due to their high cost and need for specialized equipment. The Cal Poly Wind Power Research Center is developing a low-cost, modular solution known as the LifeLine system. The previous version contained monitoring equipment, but lacked decision-making capabilities.

The present work builds on the LifeLine by developing software-based detection of blade damage. Detection is done by …

Development Of An Infrared Thermography System To Measure Boundary Layer Transition In A Low Speed Wind Tunnel Testing Environment, Damien Horton

Master's Theses

The use of infrared thermography for boundary layer detection was evaluated for use in the Cal Poly Low Speed Wind Tunnel (LSWT) and recommendations for the successful use of this technique were developed. In cooperation with Joby Aviation, an infinite wing model was designed, manufactured and tested for use in the LSWT. The wing was designed around a custom airfoil profile specific for this project, where the nearly-flat pressure gradient at a zero pitch angle would delay the chordwise onset of boundary layer transition. Steady-state, RANS numerical simulations predicted the onset of transition to occur at 0.75 x/c for the …

Computational Bone Mechanics Modeling With Frequency Dependent Rheological Properties And Crosslinking, Timothy G. Moreno

Master's Theses

Bone is a largely bipartite viscoelastic composite. Its mechanical behavior is determined by strain rate and the relative proportions of its principal constituent elements, hydroxyapatite and collagen, but is also largely dictated by their geometry and topology. Collagen fibrils include many segments of tropocollagen in staggered, parallel sequences. The physical staggering of this tropocollagen allows for gaps known as hole-zones, which serve as nucleation points for apatite mineral. The distance between adjacent repeat units of tropocollagen is known as D-Spacing and can be measured by Atomic Force Microscopy (AFM). This D-Spacing can vary in length slightly within a bundle, but …

Biological Semantic Segmentation On Ct Medical Images For Kidney Tumor Detection Using Nnu-Net Framework, Andres Bergsneider

Master's Theses

Healthcare systems are constantly challenged with bottlenecks due to human-reliant operations, such as analyzing medical images. High precision and repeatability is necessary when performing a diagnostics on patients with tumors. Throughout the years an increasing number of advancements have been made using various machine learning algorithms for the detection of tumors helping to fast track diagnosis and treatment decisions. “Black Box” systems such as the complex deep learning networks discussed in this paper rely heavily on hyperparameter optimization in order to obtain the most ideal performance. This requires a significant time investment in the tuning of such networks to acquire …