Engineering Commons^™

Visibility-Based Pursuit-Evasion In The Plane, Nicholas Michael Stiffler

Theses and Dissertations

As technological advances further increase the amount of memory and computing power available to mobile robots, we are seeing an unprecedented explosion in the utilization of deployable robots for various tasks. The speed at which robots begin to enter various domains is largely dependent on the availability of robust and efficient algorithms that are capable of solving the complex planning problems inherent to the given domain. One such domain which is experiencing unprecedented growth in recent years requires a robot to detect and/or track a mobile agent or group of agents.

In these scenarios, there are typically two players with …

Modeling Human-Structure Interaction Using A Controller System, Albert Ricardo Ortiz Lasprilla

Theses and Dissertations

The effects of human loads on structures are difficult to predict because they depend on the type of activity people are performing. However, models for typical activities such as standing, sitting and jumping have been proposed in the literature. Traditional models represent the human body as a system of lumped masses, dampers and springs arranged in a system with multiple degrees of freedom. Arguably, these models might not fully represent the human body because lumped masses, dampers and springs cannot add energy to the overall system. Furthermore, people could react differently to different levels of excitation and other environmental conditions. …

An Improved Ship Design Tool For Comparing Performance Of Multiple Ship Designs Across User-Defined Missions, Helder Jose De Almeida Pais

Theses and Dissertations

In the early stages of ship design, engineers from many different disciplines need to have confidence that a design being produced converges across the electrical, mechanical, and thermal domains, and that the design meets the needs of the stakeholders, and, that a particular design performs better or more optimally than other designs produced to accomplish a mission. The tools currently available do not permit the engineering teams to gain this insight in a reasonable amount of time. In this thesis, we discuss the improvements that we have made to our existing ship design tools in the S3D environment, allowing for …

Finite Control Set Model Predictive Control Of Direct Matrix Converter And Dual-Output Power Converters, Ozan Gulbudak

Theses and Dissertations

Model Predictive Control (MPC) with a finite control set has been successfully applied to several power converter topologies as reported in the scientific literature and research activity on predictive control techniques has increased over the last few years. MPC uses a discrete-time model of the system to predict future values of control variables for all possible control actions and computes a cost function related to control objectives to find the optimal control action. The control action which minimizes the cost function is selected and applied to the system for the next time interval. Different control objectives can be introduced in …

Modeling And Loss Analysis Of Wide Bandgap Power Semiconductor Devices, Kang Peng

Theses and Dissertations

In recent times, the development of high power density and high efficiency power converters has become critical in power electronics applications like electric vehicles, aircrafts, electric ships and so on. High-switching-frequency and high-temperature operation are required to achieve this target. However, these requirements are exceeding the theoretical material-related limits of silicon (Si) based devices. The emerging wide bandgap power semiconductor technology is a promising solution to meet these requirements. Silicon Carbide (SiC) and Gallium Nitride (GaN) are the most promising among all wide bandgap semiconductor materials. SiC and GaN have almost a three times larger bandgap (about 3eV), compared with …

Adsorption Reversibility Of So2, No2, And No On 13x And 5a Zeolites, Peter Fairchild

Theses and Dissertations

The adsorption reversibility of gasses that are typically found in flue gas for coal based power plants, such as SO2, NO2, and NO, onto 13X and 5A zeolites was presently investigated. The four individual gas mixtures containing these species consisted of 74 ppm NO (balance He), 74 ppm NO2 (balance He), 42 ppm SO2 (balance He), and 500 ppm SO2 (balance N2), which were also consistent with the values that are found in flue gas. Another gas, 15.03 mol% CO2 (balance N2), was also used in this work to evaluate the role of exposing SO2 to the zeolite on their …

Multiscale Modeling Of Water Transport And The Influence Of Water Quality Parameters On Membrane Processes, Linkel Kwabena Boateng

Theses and Dissertations

Membrane-based desalination processes have become a viable means of producing potable water to meet water resource needs in both industrialized and developing nations. Extensive experimental investigation, in conjunction with computational modeling is critical in the development of sustainable and cost-effective desalination technologies. The overall goal of this dissertation is to develop a multiscale modeling framework to elucidate water and salt transport mechanisms and the influence of water quality parameters on membrane processes. The key tasks involved in this study are: establish a criterion for estimating water flux using Bayesian inference; develop a multiscale framework to connect molecular dynamics (MD) simulations …

Characterization, Synthesis And Stabilization Of Au Based Bimetallic Catalysis For The Hydrochlorination Of Acetylene, Kerry Charles O'Connell

Theses and Dissertations

Polyvinyl chloride (PVC) is the third most-produced plastic polymer world-wide by volume after polypropylene and polyethylene. Vinyl chloride monomer, which is polymerized into PVC, is produced via mercuric chloride catalysts that deactivate as mercury sublimes into the atmosphere from the catalyst surface, resulting in substantial environmental concerns.

In an effort to rationally synthesize non-mercuric catalysts, strong electrostatic adsorption (SEA) was used to prepare highly dispersed and active gold nanoparticles over low point of zero charge (PZC) carbon to increase the active metal surface area. The use of <1.5nm gold clusters did not lead to large increases in activity as there was an increased degree of particle coalescence during reaction for activated carbon supported samples. A pronounced support effect was observed in which oxide supports completely prevented Au sintering, but was virtually inactive. This suggests that the active site for the hydrochlorination reaction involves the carbon surface.

The stabilization of carbon supported gold nanoparticles in the HCl-rich reaction environment was …

Time-Domain Measurement Of Ultrafast Magnetization Dynamics In Magnetic Nanoparticles, Brian Egenriether

Theses and Dissertations

Ultrafast time-domain measurements are made on collections of Fe3O4 magnetic nanoparticles using an inductive measurement technique. The 10nm particles are placed directly on a coplanar waveguide (CPW) situated in an adjustable external magnetic bias field. A fast-rising step current in the CPW quickly changes the orientation of the local magnetic field causing the magnetization to align in the new field configuration. This rapidly changing magnetization induces a voltage in the CPW that is detected by a sampling oscilloscope. Magnetization dynamics predicted by the Landau-Lifshitz (LL) equation including magnetic precession and phenomenological damping are observed. The time-domain data are fitted to …

Development Of Highly Active And Stable Compressive Pt Cathode Catalysts For Polymer Electrolyte Membrane Fuel Cells, Taekeun Kim

Theses and Dissertations

With the limited fossil fuel reserve and increased power demand, polymer electrolyte membrane fuel cells (PEMFC) have been considered to be a promising alternative to the current energy consumption mode due to its high energy conversion, high efficiency, and zero emissions. However, high cost, poor stability, and sluggish kinetic for oxygen reduction reaction (ORR) of Pt/C cathode catalysts are obstacles for the commercialization of PEMFC for automotive application. The observed poor stability is attributed to a corrosion of carbon supports due to low pH, high temperature, and high anodic potentials (1.0-1.5 V) at the cathode interface during start-up/shutdown conditions. Electrochemical …

Ultrathin Microporous Metal Oxide Coatings: Preparation By Molecular Layer Deposition, Characterization And Application, Zhuonan Song

Theses and Dissertations

Molecular layer deposition (MLD), a gas phase deposition technique, was applied to deposit conformal organic-inorganic hybrid coatings by conducting a series of sequential, self-limiting surface reactions on substrates with exquisite thickness control at the sub-nanometer level. Obtained organic-inorganic hybrid coatings can subsequently be converted into porous coatings by removing the organic compound. Potential of functional coatings and membranes prepared by MLD was explored for applications from adsorptive separation, water purification, to gas storage.

We demonstrated a new concept, pore misalignment, to continuously fine tune the molecular-sieving “gate” of 5A zeolite by adjusting the external porous Al2O3 MLD coating thickness. For …

Pvdf Membranes With Stable, Ultrathin Graphene Oxide (Go) Functional Coatings For Antifouling Oil/Water Separation Under Cross-Flow Condition, Lei Wang

Theses and Dissertations

Oil/water separation plays an important role in industrial wastewater treatment and environment protection. For the treatment of oily wastewater, especially for removing oil droplets with sizes in the micrometer range, ultrafiltration (UF) membrane technology is considered the most efficient method due to its high separation efficiency and relatively simple operational process. However, caused by the deposition of the oil droplets onto the membrane surface and into the membrane pores, the fouling of UF membranes shortens their service time and degrades their separation performance in practical applications.

In this work, graphene oxide (GO) was utilized as a novel coating material to …

Determination Of Non-Nuclear Alternative To The Nuclear Density Gauge Through Laboratory And Field Testing, Janine Abyad

Theses and Dissertations

Pavement performance is dependent on the compaction quality of unbound subgrade and base/subbase layers beneath flexible pavements. Pavement distresses can be linked to compaction defects within these layers. In current practice, the New Jersey Department of Transportation (NJDOT) utilizes the nuclear density gauge (NDG) for evaluating compaction quality based on minimum density requirements, typically 95% of the Proctor maximum dry density (MDD). However, there are concerns with using the NDG. The goal of this study was to replace the NDG with non-nuclear alternative method(s) as acceptance tools during field compaction. To achieve this, a laboratory procedure for compacting large samples …

An Investigation In Construction Cost Estimation Using A Monte Carlo Simulation, Jeffrey D. Buchholtz

Theses and Dissertations

The Air Force estimates military construction (MILCON) costs early in a project’s development as a part of the funding approval process. However, many of the initial cost estimates deviate significantly more than expected from the actual project costs, hindering funding allocation efforts. There is a need for improved estimation techniques. This research examines a cost estimation model for the initial programming stages of a project when only general scope information is available.

This study develops a Monte Carlo simulation based on historical construction cost data to predict project costs base on facility type. For a given facility type, the research …

The Effects Of Ionizing Radiation And Oxidizing Species On Strains Of Deinococcus Radiodurans Lacking Endogenous Oxidative Protection Methods, Dylan L. Klawuhn

Theses and Dissertations

Multiple strains of Deinococcus radiodurans were transformed, creating knockout mutations in genes responsible for manganese ion transport, manganese and copper/zinc super-oxide dismutase, and bacillithiol synthesis. These mutated strains were then irradiated with ~20,000 Gys. The results showed that the mutated strains had a higher sensitivity to ionizing radiation, those responsible for bacillithiol synthesis having an increase in sensitivity 3000 times more than wild type Deinococcus radiodurans. In addition to radiation the mutated strains were also exposed to paraquat, an oxidizing herbicide. Strains missing manganese super-oxide dismutase showed increased sensitivity.

Using Approximate Dynamic Programming To Solve The Stochastic Demand Military Inventory Routing Problem With Direct Delivery, Ethan L. Salgado

Theses and Dissertations

A brigade combat team must resupply forward operating bases (FOBs) within its area of operations from a central location, mainly via ground convoy operations, in a way that closely resembles vendor managed inventory practices. Military logisticians routinely decide when and how much inventory to distribute to each FOB. Technology currently exists that makes utilizing cargo unmanned aerial vehicles (CUAVs) for resupply an attractive alternative due to the dangers of utilizing convoy operations. However, enemy actions, austere conditions, and inclement weather pose a significant risk to a CUAV's ability to safely deliver supplies to a FOB. We develop a Markov decision …

Preprocessing Techniques To Support Event Detection Data Fusion On Social Media Data, Brandon T. Davis

Theses and Dissertations

This thesis focuses on collection and preprocessing of streaming social media feeds for metadata as well as the visual and textual information. Today, news media has been the main source of immediate news events, large and small. However, the information conveyed on these news sources is delayed due to the lack of proximity and general knowledge of the event. Such news have started relying on social media sources for initial knowledge of these events. Previous works focused on captured textual data from social media as a data source to detect events. This preprocessing framework postures to facilitate the data fusion …

Meeting The Dod’S Tactical Weather Needs Using Cubesats, Shayna K. Mckenney

Theses and Dissertations

This thesis investigates a CubeSat design that uses Commercial-Off-The-Shelf (COTS) components to capture, store, process, and downlink collected terrestrial weather data at resolutions near stat-of-the-art. The weather phenomena to be detected and transmitted in a timely manner are cloud formations, wind profiles, ocean currents, sea state, lightning, temperature profiles, and precipitation. It is hypothesized and shown that the proposed design will provide an improvement on the current U.S. tactical weather collection satellites because of the anticipated increased reliability and lowered cost to build and maintain the proposed CubeSat constellation. The methodology employed a multi-phase approach through the collective research of …

Test And Verification Of A Cubesat Attitude Determination And Control System In Variable Magnetic Fields, Eric A. Bassett

Theses and Dissertations

The Center for Space Research and Assurance (CSRA) at the Air Force Institute of Technology (AFIT) continues to explore CubeSat initiatives for solving many current space security issues. Regardless of the mission requirements, the success of the Cube- Sat on orbit frequently depends on the Attitude Determination and Control System (ADCS) functioning correctly. Previous research at AFIT has demonstrated single axis control on a spherical air bearing test bed incorporated within a Helmholtz cage utilizing artificially strong magnetic fields for better signal to noise ratios which are not experienced on orbit. This research explores the process of redesigning, testing, and …

Design And Experimentation Of A Premixed Rotating Detonation Engine, Ionio Q. Andrus

Theses and Dissertations

Desire for a more efficient air breathing engine has shifted research attention to the Rotating Detonation Engine (RDE). Detonation is a more efficient combustion process than deflagration and provides a pressure gain. The RDE detonation cycle occurs in a compact volume to produce a high specific impulse engine. Computational fluid dynamic (CFD) models have predicted higher specific impulse and detonation wave speeds than has been seen in experimental RDE. The CFD models frequently assume premixed reactants and ignore inlet geometries to facilitate rapid computation. An experimental premixed RDE was sought to test if the premixed assumption in CFD was the …

Efficient Employment Of Large Format Sensor Data Transfer Architectures, Jeffrey R. Oltmanns

Theses and Dissertations

Due to the increasing quantity of data collected by Air Force intelligence, surveillance and reconnaissance (ISR) assets and the focus on timely access to the data collected by these systems, operational data transfer network architectures have become a critical component of their employment in the intelligence production process. Efficient utilization of the provided long-haul communications component of the ISR system improves the value of the single asset to the warfighter and enables connectivity of additional assets via the data transfer network architecture. This research effort focused on the creation and implementation of a structured test design methodology based on the …

Microfacet Wavelength Scaling Of The Brdf, Samuel E. Freda

Theses and Dissertations

The bidirectional reflectance distribution function (BRDF) describes realistic scattering of light off materials by relating incident irradiance to outbound radiance. One popular class of BRDF models assumes a surface is comprised of tiny microfacets. The drawback of microfacet BRDFs is that they often no not contain specific material parameters and neglect wavelength effects. Wave optics BRDF expressions, however, can describe wavelength effects at the expense of being more computationally cumbersome. Previous work of following a Beckmann-Kirchhoff derivation of BRDF, then relating wave optics BRDF coordinates to microfacet coordinates led to a complicated, but versatile, BRDF. In this work, the infinite …

Design, Manufacturing, And Testing Of A Small Through-Flow Wave For Use Within The Brayton Cycle, Micahel J. Mcclearn

Theses and Dissertations

With the ever growing popularity of drones and other unmanned aerial vehicles for military, commercial, and private usage, there is a desire to improve performance in terms of range, altitude, and flight speed. Current technology uses either electric motors or internal combustion engines: both piston and jet engine types. These sorts of engines undergo significant efficiency degradation as their size decreases. While some efficiency may be recovered via intensive design studies, the cycles are approaching the limit to their operating physics. A possible solution to this is to change the operating physics to something more immune to scaling losses; a …

The Effect Of Projectile Nose Shape On The Formation Of The Water Entry Cavity, Jeremy Conrad Ellis

Theses and Dissertations

This research focuses on the effect of several convex and concave nose shapes on cavity formation for both hydrophilic and hydrophobic projectiles. It specifically investigates the effect of convex shape on the threshold velocity for cavity formation as well as the effect of concave shapes on cavity formation in terms of impact velocity, geometry of the concave shape and wettability of the projectile. For the convex cases, the streamlined axisymmetric shape significantly increases the threshold velocity when cavities form and is most pronounced for the ogive and cone. The study demonstrates that measuring the wetting angle and impact velocity is …

Investigation Of Thermal Scaling Effects For A Turbine Blade Leading Edge And Pressure Side Model, Ryan A. Lynch

Theses and Dissertations

Recent experiments have attempted to quantify the overall cooling effectiveness at elevated temperature conditions. The Film Cooling Rig (FCR) at the Air Force Institute of Technology has been modified to better match the configuration of a similar large scale, low temperature rig at the Air Force Research Laboratory. This has enabled comparison and trend identification of how various properties scale from the low to high temperature condition. Various internal cooling and hole geometry configurations were investigated over a range of temperatures while utilizing the thermal scaling capability of Inconel 718. Film cooling trends and measures of overall effectiveness were matched, …

Air Mobility Future: Evolving Command And Control Relationships In The Information Age, Ian M. Slazinik

Theses and Dissertations

This research paper analyzes information flow through theater Air Mobility Command and Control (C2) organizations. The purpose is to uncover guidelines going forward to adapt organizational structure and processes to increase the speed and reach of information. These guidelines could assist with improving organizational agility and decision making while adapting to future trends in the broader C2 enterprise. To collect data, the researcher conducted interviews with seventeen C2 experts with experience at various levels of C2, from worldwide to theater Air Mobility C2 organizations, from Air Mobility C2 leadership, to experts in non-mobility C2 divisions. Interview subjects shared their perceptions …

Non-Schmid Effects And Criteria For Dislocation Nucleation On Different Slip Systems At Grain Boundaries, Richard Durtschi Wyman

Theses and Dissertations

Criteria for grain boundary dislocation nucleation are developed. A bicrystal containing two grain boundaries is placed under varying triaxial stress states using molecular dynamics. The local resolved shear, normal, and co-slip stresses needed for grain boundary dislocation nucleation are found. A framework is developed to detect the slip system grain boundary dislocation nucleation occurs on. A survey of the different ways grain boundary dislocation nucleation occurs in the sample shows a single grain boundary can nucleate dislocations in a rich variety of ways. Using the nucleation system and resolved stress values, criteria for grain boundary dislocation nucleation on different slip …

Duplicate With Choose: Using Statistics For Fault Mitigation, Jon-Paul Anderson

Theses and Dissertations

This dissertation presents a novel technique called duplicate with choose (DWCh) which is a modification of the fault detection technique duplicate with compare (DWC). DWCh adds a smart decider block to DWC that monitors the duplicated circuits and decides which circuit is fault free when a fault occurs. If chosen correctly, DWCh is able to mask faults at a lower cost than conventional techniques like TMR.This dissertation derives reliability expressions for DWCh showing that under ideal conditions its reliability exceeds the most commonly used fault masking technique for spacecraft, triple modular redundancy. For non-ideal conditions, DWCh provides a lower cost …

An Investigation Of The Impact A Rov Competition Curriculum Has On Student Interest In Stem, Specifically Technology And Engineering, Daniel Gordon Bates

Theses and Dissertations

This research investigates the impact a Remotely Operated Vehicle (ROV) program has on student interest in, and perception of, technology and engineering (sTEm). ROV programs embed areas of science, technology, engineering and math (STEM) into their curriculum; however, emphasis for this study is placed on interest and perception of the "T" and "E" of STEM. Although there are many articles detailing the benefits of ROV programs, there is little empirical data documenting the impact on student interest and perception of sTEm. This study outlines the background of a few major ROV programs in the U.S.; specifically Utah Underwater Robotics (UUR), …

Optimum Pick Point Locations For Straight, Singly Symmetric Steel Plate Girders, J. Andrew Pratt

Theses and Dissertations

Optimal pick point location is discovered in order to have the full buckling capacity of a suspended, non-prismatic, singly symmetric plate girders. The results show that a significant increase in stability occurs at the pick point location of 0.25L, where L is the span length. This recommendation can be utilized in the field to save construction cost and time because of how simplistic it is to use. A finite element software, ABAQUS 6.14, is used to determine the buckling capacities at different pick point locations and of different cross sections. The dimension of the cross sections and span lengths for …