Engineering Commons^™

Formation Flight Of Earth Satellites On Kam Torus Using Classical Orbital Elements, Marissa C. Reabe

Theses and Dissertations

This research uses the KAM theory that has been refined by Wiesel to show that Earth-satellites dynamics can be represented by an integrable Hamiltonian system with a small perturbation, like Earths geopotential. The satellite will follow a torus in phase space and remain on that KAM torus for all time unless acted on by a non-conservative force. A torus frequency was calculated, in this research, using a truth model in System Tool Kit (STK) and the High Precision Orbit Propagator (HPOP) to develop an accurate ephemeris file listing the Classical Orbital Elements (COEs). The frequencies found from the truth model …

Framework For Industrial Control System Honeypot Network Traffic Generation, Htein A. Lin

Theses and Dissertations

Defending critical infrastructure assets is an important but extremely difficult and expensive task. Historically, decoys have been used very effectively to distract attackers and in some cases convince an attacker to reveal their attack strategy. Several researchers have proposed the use of honeypots to protect programmable logic controllers, specifically those used to support critical infrastructure. However, most of these honeypot designs are static systems that wait for a would-be attacker. To be effective, honeypot decoys need to be as realistic as possible. This paper introduces a proof-of-concept honeypot network traffic generator that mimics genuine control systems. Experiments are conducted using …

A Framework For Categorization Of Industrial Control System Cyber Training Environments, Evan G. Plumley

Theses and Dissertations

First responders and professionals in hazardous occupations undergo training and evaluations for the purpose of mitigating risk and damage. For example, helicopter pilots train with multiple categorized simulations that increase in complexity before flying a real aircraft. However in the industrial control cyber incident response domain, where incident response professionals help detect, respond and recover from cyber incidents, no official categorization of training environments exist. To address this gap, this thesis provides a categorization of industrial control training environments based on realism. Four levels of environments are proposed and mapped to Blooms Taxonomy. This categorization will help organizations determine which …

Applying Cyber Threat Intelligence To Industrial Control Systems, Matthew P. Sibiga

Theses and Dissertations

A cybersecurity initiative known as cyber threat intelligence (CTI) has recently been developed and deployed. The overall goal of this new technology is to help protect network infrastructures. Threat intelligence platforms (TIPs) have also been created to help facilitate CTI effectiveness within organizations. There are many benefits that both can achieve within the information technology (IT) sector. The industrial control system (ICS) sector can also benefit from these technologies as most ICS networks are connected to IT networks. CTI and TIPs become resourceful when using indicators of compromise (IOCs) from known ICS malware attacks and an open source intrusion detection …

On Proportionate And Truthful International Alliance Contributions: An Analysis Of Incentive Compatible Cost Sharing Mechanisms To Burden Sharing, William N. Caballero

Theses and Dissertations

Burden sharing within an international alliance is a contentious topic, especially in the current geopolitical environment, that in practice is generally imposed by a central authority's perception of its members' abilities to contribute. Instead, we propose a cost sharing mechanism such that burden shares are allocated to nations based on their honest declarations of the alliance's worth. Specifically, we develop a set of multiobjective nonlinear optimization problem formulations that respectively impose Bayesian Incentive Compatible (BIC), Strategyproof (SP), and Group Strategyproof (GSP) mechanisms based on probabilistic inspection efforts and deception penalties that are budget balanced and in the core. Any feasible …

A Scenario-Based Parametric Analysis Of Stable Marriage Approaches To The Army Officer Assignment Problem, Matthew D. Ferguson

Theses and Dissertations

This paper compares linear programming and stable marriage approaches to the assignment problem under conditions of uncertainty. Robust solutions should exhibit reduced variability in the presence of one or more additional constraints. Several variations of each approach are compared with respect to solution quality, as measured by the overall social welfare among Officers and Assignments, and robustness as measured by the number of changes after a number of randomized perturbations. We examine the contrasts between these methods in the context of assigning Army Officers among a set of identified assignments. Additional constraints are modeled after realistic scenarios faced by Army …

Survival Analysis Of Us Air Force Officer Retention Rate, Courtney N. Franzen

Theses and Dissertations

Personnel retention is a matter of great interest in the private and public sectors. In the public sector--specifically the US Air Force--maintaining appropriate retention levels of rated officers is paramount as these officers are the backbone of the Air Force’s mission. As part of the effort to ensure proper retention rates for rated officers, retention models are created by the Air Force Personnel division that assist in predicting future retention patterns and accession needs. The techniques for creating these models, known as the "sustainment line," involve utilizing average retention percentages obtained from historical data. In this study, more statistical-based methods …

A Multi-Fluid Model For Microstructure Formation In Polymer Membranes, Douglas R. Tree, Kris T. Delaney, Hector D. Ceniceros, Tatsuhiro Iwama, Glenn H. Fredrickson

Faculty Publications

We develop a multi-fluid model for a ternary polymer solution using the Rayleighian formalism of Doi and Onuki, and give an efficient pseudo-spectral method for solving both the diffusion and momentum equations that result. Subsequently, we find that the numerical simulation is capable of describing systems at the micron length-scale and easily reaches millisecond time-scales. In addition, we characterize the model thermodynamics and kinetics including the (i) phase behavior, (ii) structure of the interfaces, (iii) mutual diffusion coefficients, (iv) bulk spinodal decomposition kinetics with and without hydrodynamics and (v) spinodal decomposition in the presence of an interface with a non-solvent …

A Study Of Iron-Nitrogen-Carbon Fuel Cell Catalysts: Chemistry – Nanostructure – Performance, Michael J. Workman

Nanoscience and Microsystems ETDs

Fuel cells have the potential to be a pollution-free, low-cost, and energy efficient alternative to the internal combustion engine for transportation and small-scale stationary power applications. The current state of fuel cell technology has already achieved two of these three lofty goals. The remaining barrier to wide-scale deployment is the high cost, which is primarily caused by dependence on large amounts of platinum to catalyze the energy conversion reactions. To overcome this barrier and facilitate the integration of fuel cells into mainstream applications, research into a new class of catalyst materials that do not require platinum is needed.

There has …

Relating Film Cooling Performance Between Ambient And Near Engine Temperatures, Christopher J. Vorgert

Theses and Dissertations

This thesis explores multiple topics, including the relative importance of nondimensional parameters that relate film cooling performance within different temperature regimes and the effects of internal coolant flow and coolant temperature on overall film cooling effectiveness. A Hastelloy model representative of a turbine blade was utilized for IR tests. Near engine temperatures were produced via premixed propane and air combustion in a Well-Stirred Reactor (WSR) with air supplied as the film coolant gas. Near ambient conditions used heated air for freestream flow and carbon dioxide, argon, or air as film coolant gases. It was found that even with multiple matched …

Identifying Partnership Opportunities At Air Force Installations: A Geographic Information Systems Approach, Corey R. Degroot

Theses and Dissertations

The excess capacity found in the Department of Defense real property portfolio creates challenges for leaders to provide resilient installations. Combining this fact with current funding trends makes decisions on how to properly maintain infrastructure even more challenging. The Air Force Partnership Initiative provides tools for installations to leverage community capabilities and resources to achieve savings and improve quality on Air Force installations and can reduce the real property footprint. This research proposes a method for assessing the viability of a partnership between Air Force installations and their nearby communities.
This research effort created a tool capable of investigating off-base …

Cost Versus Risk: The Policy Of Nuclear Weapon Maintenance Of Tritium Based Limited Life Components, Michael P. Mason

Theses and Dissertations

This research develops a method to measure the cost to society of current maintenance policy for the exchange of tritium based limited life components within nuclear weapons. The incentives for the Department of Energy and Department of Defense which causes either a substantial cost or substantial risk to be accepted by either Department. A simulation model is created to measure the current policy and compare it to different policies in order to recommend a policy that would minimize the cost to society. The measurement of the cost to society will offer decision makers insight into the ramifications of their decisions.

Using Markov Decision Processes With Heterogeneous Queueing Systems To Examine Military Medevac Dispatching Policies, Phillip R. Jenkins

Theses and Dissertations

major focus of the Military Health System is to provide efficient and timely medical evacuation (MEDEVAC) to battlefield casualties. Medical planners are responsible for developing dispatching policies that dictate how aerial military MEDEVAC units are utilized during major combat operations. The objective of this research is to determine how to optimally dispatch MEDEVAC units in response to 9-line MEDEVAC requests to maximize MEDEVAC system performance. A discounted, infinite horizon Markov decision process (MDP) model is developed to examine the MEDEVAC dispatching problem. The MDP model allows the dispatching authority to accept, reject, or queue incoming requests based on the request's …

Refugees In Urban Environments: Social, Economic, And Infrastructure Impacts, Garrett L. Jameson

Theses and Dissertations

The United Nations High Commissioner for Refugees has estimated that in 2015 there were 21.3 million refugees worldwide; it is estimated that 1.8 million of these persons were newly displaced during 2015. As refugees leave their country to seek the protection of another nation's government, they generally flow into urban areas. The impact of this flow on cities and on the refugees, themselves, is not fully understood. This study is focused on the impact of government policy decisions on the social, legal, and economic integration of refugees within an urban environment. Investigation into this topic resulted in the development of …

Simulation Modeling And Analysis Of Deployed F-16 Operations And Logistics Support, Gregory D. Potts Ii

Theses and Dissertations

The purpose of this thesis is to reinforce and build upon past efforts identifying and demonstrating the need to better represent logistic capabilities and constraints within the realm of wargaming, war planning, and other analyses requiring the modeling of Air Force combat operations. We develop a framework for the porting of relevant logistic information and requirements from a reliable data source (LCOM- ATK) into a discrete event simulation environment (SIMIO), providing a simulation model for enhanced and robust analyses. The simulation we create explicitly reflects (for a selected subset of Work Unit Codes) the maintenance manpower, resources, and parts required …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 900°C In Air And In Silicic Acid-Saturated Steam, Ronald K. Mitchell

Theses and Dissertations

Advanced SiC/SiC ceramic matrix composites (CMCs) are being considered for demanding aerospace applications such as aircraft engine hot-section components. In these applications the composites will be subjected to cyclic and sustained loadings at elevated temperature in aggressive combustion environments. Current aircraft engines employ Nickel-based superalloys in applications such turbine blades, where the metallic alloys must perform at or near their operating temperature limits in highly corrosive environments. The SiC/SiC composites, which offer low density, high strength and fracture toughness at elevated temperatures could potentially replace Nickel-based superalloy in aircraft engine applications. However, before the SiC/SiC composites can be safely used …

Stressed Oxidation Of Hafnium Diboride In Air At 1500°C, Thomas A. Bowen

Theses and Dissertations

Hypersonic vehicles with narrow airfoils produce thin boundary layers and shock temperatures in excess of 2000°C, exceeding the operating limits of traditional aerospace materials. The use of ultra-high temperature ceramics (UHTCs) allows for operating temperatures far exceeding those of metallic alloys. One such UHTC is hafnium diboride (HfB₂). Transition metal diborides generally experience significant oxidation degradation at elevated temperatures. The use of additives, such as silicon carbide (SiC) has been shown to reduce the oxidation of transition metal diborides. This research focused on the compressive creep of HfB₂ with varying amounts of SiC in air at 1500°C. …

Investigating Analytical And Numerical Methods To Predict Satellite Orbits Using Two-Line Element Sets, Adam T. Rich

Theses and Dissertations

As Low Earth Orbit (LEO) contains an ever-increasing number of objects, the prediction of future object positions must be precise in order to avoid collisions. Object positions are distributed in two-line element (TLE) sets and are generated using the analytical propagator known as Simplified General Perturbations 4 (SGP4). However, a numerical integrator called Special Perturbations (SP) provides an alternative approach to TLE generation and propagation. In this thesis, TLE accuracy was determined with both models, and the length of time that a single element set can provide valid information was also established. With two-line element sets as data, comparisons were …

Satellite Communications In The V And W Band: Natural And Artificial Scintillation Effects, David A. Smith

Theses and Dissertations

In a natural atmospheric environment the troposphere will be the primary source of loss with the ionosphere loss being negligible. If the ionosphere was disturbed from a high altitude nuclear explosion (HANE) more than three times the amount of electrons would be present in the ionosphere and could represent a source of significant loss. In order to determine the amount of electrons distributed from a HANE, GSCENARIO, developed by Defense Threat Reduction Agency was used. The two sources of loss that were examined was signal absorption and amplitude scintillation. Signal loss was determined using GSCENARIO and amplitude scintillation loss was …

Analysis Of Human And Agent Characteristics On Human-Agent Team Performance And Trust, Anthony J. Hillesheim

Theses and Dissertations

The human-agent team represents a new construct in how the United States Department of Defense is orchestrating mission planning and mission accomplishment. In order for mission planning and accomplishment to be successful, several requirements must be met: a firm understanding of human trust in automated agents, how human and automated agent characteristics influence human-agent team performance, and how humans behave. This thesis applies a combination of modeling techniques and human experimentation to understand the concepts aforementioned. The modeling techniques used include static modeling in SysML activity diagrams and dynamic modeling of both human and agent behavior in IMPRINT. Additionally, this …

Sound Based Positioning, David L. Weathers

Theses and Dissertations

With a growing interest in non-GPS positioning, navigation, and timing (PNT), sound based positioning provides a precise way to locate both sound sources and microphones through audible signals of opportunity (SoOPs). Exploiting SoOPs allows for passive location estimation. But, attributing each signal to a specific source location when signals are simultaneously emitting proves problematic. Using an array of microphones, unique SoOPs are identified and located through steered response beamforming. Sound source signals are then isolated through time-frequency masking to provide clear reference stations by which to estimate the location of a separate microphone through time difference of arrival measurements. Results …

Recommended Selective Maintenance And Rehabilitation Treatment Approach For Air Force Primary Rigid Runway Pavement Systems, Christopher M. Twigg

Theses and Dissertations

The Air Force is facing the challenge to preserve the current inventory of 154 million square yards of paved airfield assets while at the same time reducing the budget by $36.2 billion between fiscal years 2015-2019. This research sought to determine a selective maintenance and rehabilitation treatment approach that allocates resources efficiently to preserve the degrading pavement assets in the financially constrained environment. Air Force pavement inspection reports from the past five years provided 4289 observed pavement distress data points for this research. The data was inputted into the pavement management software, PAVER, to calculate the Pavement Condition Index (PCI) …

Time-Dependent Validation Of Finite Element Strain Distribution Of A Plastically-Deformed Plate Via Digital Image Correlation, Kevin R. Knapp

Theses and Dissertations

Generation of residual stress is an essential step in the generation of Goodman data via Air Force Research Laboratory's vibration-based fatigue test. Conventional Goodman data is constructed through uniaxial fatigue testing at a rate of 40 Hz, while the vibration-based testing excites stresses at 1,600 Hz in a stress state that is similar to those seen in gas turbine engine airfoils. A pre-strain procedure is conducted to form residual tensile stress, which serves as a steady stress when the specimen is subjected to fully-reversed vibration-based fatigue loads. This steady tensile stress is desired at the fatigue zone of the test …

Making Light-Weight Mg-Metal Laminated Nanocomposites, Soodabeh Azadehranjbar, Xinyan Xie, Jeffrey E. Shield, Jian Wang

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Magnesium is the lightest of all the engineering metals. Replacing steel structural materials with Mg-based materials in automotive applications would boost fuel. However, conventional Mg alloys typically suffer from low strength and poor deformability due to very few slip systems and easy twinning. Alloying Mg with other materials and microstructural engineering are promising approaches to increase ductility and strength of Mg. According to Wang et al., interfaces with low energy and high coherency may effectively constrict the nucleation of twins in Mg. In this work, Mg-metal multilayered nanocomposites will be produced by melt spinning procedure and the layers’ mechanical properties …

Light Olefin Production By Cracking Nannochloris Oculata Microalgae Using Aluminosilicate Catalysts, Gaurav Goyal

USF Tampa Graduate Theses and Dissertations

The global demand and sustainability concerns for producing light olefins encouraged researchers to look for an alternative and sustainable feedstock. Alkenes, such as ethene, propene and butene, are known as light olefins. Olefins are the backbone of the chemical industry because they serve as the chemical building blocks for the manufacture of polymers, fibers, and numerous organic chemicals. Feedstocks such as naphtha, natural gas and liquefied petroleum gas (LPG) are currently used for producing light olefins, but they are non-renewable and hence unsustainable. In contrast, biomass as a potential feedstock for the production of fuels and chemicals is renewable. Microalgae, …

Simulation Studies On Ecg Vector Dipole Extraction In Liquid Medium, Pratheek Michael

USF Tampa Graduate Theses and Dissertations

To circumvent some inherent problems in the conventional ECG, this research reinvestigates an ‘unassisted’ approach which enables ECG measurement without the placement of leads on the body. Employed in this research is a widely accepted assumption that the electrical activity of the heart may be represented, largely, by a 3-D time-varying current dipole (3D-CD). From the PhysioBank database, mECG and fECG data were obtained, and Singular Value Decomposition (SVD) was performed to estimate the time-varying Vector ECG dipole. To determine the sensing matrix responsible for transforming the activity of the 3D-CD into the potential distribution on the surface of the …

Electric Bus Systems. A Case Study And Optimization Study, Florida Solar Energy Center, Nan Qin

FSEC Energy Research Center®

Pure electric buses (EBs) offer an alternative fuel for the nation's transit bus systems. To evaluate EBs in a transit setting, this project investigated the five electric bus fleet of the StarMetro transit system of the city of Tallahassee, FL. For the study, the implementing strategy, route distances and timings, charging times, fuel economies, impact of chargers, and maintenance and operational characteristics were analyzed. The results were compared to a baseline five diesel bus fleet. The results showed that even with a four-fold improvement in fuel efficiency, the operational costs of electric buses were only 10% lower than that for …

Fuel Cell Vehicle Technologies Final Report, Florida Solar Energy Center, Nan Qin

FSEC Energy Research Center®

Fuel cell electric vehicles (FCEVs) use hydrogen as fuel and exhaust only water and heat. They provide driving ranges and fueling times comparable to gasoline vehicles. Despite the advantages, FCEVs have been in and out of the spot light of the auto industry for the past several decades. As FCEVs finally moved from concept demonstration to commercialization in 2015, it is critical to analyze the opportunities and challenges this technology brings. This project placed emphasis on four areas: (1) Analysis of the development of FCEVs from a historic and technology point of view; (2) analysis of hydrogen fueling station infrastructure …

Energy From Thin Air: Compressed Air Power Harvesting Systems, Zachary Sadler, Matthew Jones

Journal of Undergraduate Research

Energy is an important resource within the world we live. The demand for power requires new energy resources. Much of the power that is generated is eventually wasted in the form of waste heat. As much as 435 GW of energy is transferred from virtually all energy conversion devices and processes to the atmosphere as wasted heat ^[1]. Converting as much as one percent of this waste heat into electrical power would eliminate the need for 18 average size (236 MW) ^[2] coal red power plants. A significant portion of this waste heat production is due to air compression …

Effects Of Microstructure And Alloy Concentration On The Corrosion And Tribocorrosion Resistance Of Al-Mn And We43 Mg Alloys, Hesham Y. Saleh Mraied

USF Tampa Graduate Theses and Dissertations

The design of new engineering materials resistant to both wear damage and corrosion degradation becomes increasingly demanding in complex service conditions. Unfortunately, there is typically a tradeoff between wear and corrosion resistance, even for important passive metals such as Al alloys. This is because the presence of precipitates hardens the material but at the same time lead to unfavorable galvanic coupling between the precipitates and the matrix, resulting in accelerated corrosion. This work showed that Al (or Mg) supersaturated solid solution formed using non-equilibrium methods exhibited enhanced corrosion resistance without compromising strength. For Al, alloying with Mn up to ~ …