Engineering Commons^™

The Effect Of Ph And Pulsed Ultraviolet Light Emitting Diode Duty Cycles On The First Order Rate Constant And Byproduct Profile Of The Advanced Oxidation Of Tartrazine, Brandon M. Stewart

Theses and Dissertations

Water treatment capability is required for military operations, production of drinking water, and industrial wastewater treatment. The Advanced Oxidation Process (AOP) is one of many viable steps for treating water; however, it is important to understand the byproducts of the treatment process to avoid creating other constituents more severe than the first. Tartrazine (TAR) was oxidized with pulsed Ultra- Violet (UV) Light Emitting Diodes (LEDs) in combination with hydrogen peroxide (H2O2) in an AOP at the laboratory scale. The relative concentration of TAR was reduced from 1 to between 1 – 0.75 over pH values between 6 and 9, and …

Optimizing Allocation Of U.S. Humanitarian Civic Assistance Projects In Support Of Developing Foreign Democracy, Christopher E. Wittman

Theses and Dissertations

Humanitarian projects in foreign countries are funded by the U.S. government to foster peace, prosperity, and the spread of democratic ideals around the globe. The type and scope of projects are restricted by current doctrine and funding regulations. Specifically in 2014, USAF personnel supported medical and educational construction projects/programs in the country of Belize. Within Belize, medical and educational projects were funded under the Humanitarian and Civic Assistance (HCA) program through the NEW HORIZONS exercise. Fiscal constraints, including shrinking budgets due to sequestration, have placed greater emphasis in the responsible distribution of resources and foreign assistance. The purpose of this …

Liquid Fuel Film Cooling: A Cfd Analysis With Hydrocarbon Fuel, Jacob D. Bills

Theses and Dissertations

Cooling of liquid rocket engine combustion chambers and nozzles is a critical component to liquid rocket engine design. A common method of cooling is liquid fuel film cooling. Liquid fuel is injected along the surface of the wall to act as a barrier against the core combustion gases. A numerical model is developed for simulating liquid fuel _lm cooling in a rocket engine using a hydrocarbon fuel. The model incorporates turbulent multiphase ow with species transport within the commercial ANSYS® Fluent CFD software. Conjugate heat transfer is simulated through walls containing embedded cooling channels. A novel User Defined Function is …

Formation Flight Of Earth Satellites On Low-Eccentricity Kam Tori, Christopher T. Craft

Theses and Dissertations

The problem of Earth satellite constellation and formation flight is investigated in the context of Kolmogorov-Arnold-Moser (KAM) theory. KAM tori are constructed utilizing Wiesel’s Low-Eccentricity Earth Satellite Theory, allowing numerical representation of the perturbed tori describing Earth orbits acted upon by geopotential perturbations as sets of Fourier series. A maneuvering strategy using the local linearization of the KAM tangent space is developed and applied, demonstrating the ability to maneuver onto and within desired torus surfaces. Constellation and formation design and maintenance on KAM tori are discussed, along with stability and maneuver error concerns. It is shown that placement of satellites …

Localized Plasma Measurement During Instability Modes In A Hall Thruster, David A. Cunningham

Theses and Dissertations

Hall thrusters are a key technology for current and future unmanned satellites, striking a balance between thrust and fuel economy suitable for many mission profiles of interest. Despite their extensive flight heritage and a large body of research, many phenomena occurring in the plasma discharge of Hall thrusters are not well understood. A combination of intrusive and non-intrusive measurement techniques were used to investigate the properties of the exhaust plume of two Hall thrusters and correlate optical characteristics of oscillating modes with the plasma potential and azimuthal current distribution during those modes. A strong trend was found associating the optical …

Key Detection Rate Modeling And Analysis For Satellite-Based Quantum Key Distribution, Jonathan C. Denton

Theses and Dissertations

A satellite QKD model was developed and validated, that allows a user to determine the optimum wavelength for use in a satellite-based QKD link considering the location of ground sites, selected orbit and hardware performance. This thesis explains how the model was developed, validated and presents results from a simulated year-long study of satellite-based quantum key distribution. It was found that diffractive losses and atmospheric losses define a fundamental trade space that drives both orbit and wavelength selection. The optimal orbit is one which generates the highest detection rates while providing equal pass elevation angles and durations to multiple ground …

Effects Of Additive Manufacturing Methods On The Dynamic Properties Of 15-5ph Stainless Steel, Allison A. Dempsey

Theses and Dissertations

Experimental research was conducted to determine the dynamic properties and characterize the microstructure of 15-5PH Stainless Steel manufactured through Direct Metal Laser Sintering (DMLS) additive manufacturing (AM) processes and heat treated using common heat treatment protocols. A thorough understanding of the material's properties is necessary before such parts are utilized in an operational capacity. Of the five builds, two deviated significantly from the specified composition of 15-5PH stainless steel. The remaining three builds, possessing the desired composition and crystalline structure, were tested in compression and tension at two strain rates. Tension tests using a reflected wave and a momentum trap …

Surface Roughness Of Electron Beam Melting Ti-6al-4v Effect On Ultrasonic Testing, Evan T. Hanks

Theses and Dissertations

Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of Electron Beam Melted (EBM) additively manufactured Ti-6Al-4V. Additive Manufacturing (AM) is a developing technology with many potential benefits, but certain challenges posed by its use require further research before AM parts are viable for widespread use in the aviation industry. Possible applications of this new technology include, Aircraft Battle Damage Repair (ABDR), small batch manufacturing to fill supply gaps, and replacement for obsolete parts. The research presented here assesses the effectiveness of ultrasonic inspection in detecting manufactured flaws in EBM manufactured Ti-6Al-4V. EBM products are …

Enhanced Flow Migration In Full Annular Ultra Compact Combustor, Nicholas A. Gilbert

Theses and Dissertations

Since combustion efficiency in modern jet engines has stabilized, attention has turned to improving the combustor by improving the thrust-to-weight ratio. The Ultra Compact Combustor (UCC) is a means to reduce the weight of the combustor while ensuring exhaust meets increasingly stringent government emission standards. Combustion occurs within the UCC under a g-load in the circumferential direction, which maintains combustion efficiency while decreasing axial combustor length. Previous analysis optimized the combustion chamber flame characteristics with a common upstream air source. Previously, issues for the UCC were inspired by integration into a traditional axial turbojet. The focus of this investigation was …

Investigation Into Reynolds Number Effects On A Biomimetic Flapping Wing, Daniel K. Hope

Theses and Dissertations

This research investigated how the nature of the wing changed as a function of Reynolds number by measuring the forces produced by wings with varying characteristic lengths, tested at varying air densities. Increasing the wing span increased the overall weight of the wing, which reduced the 1st natural frequency; and did not result in an increase in vertical force over the baseline 50 mm wing. However; if the decrease in natural frequency was counteracted by increasing the thickness of the joint material in the linkage mechanism, vertical force production did increase over the baseline wing planform. Negligible forces and moments …

Evaluation Of Unmanned Aircraft Flying Qualities Using Jsbsim, Joshua P. Kim

Theses and Dissertations

Flying qualities data can be used to predict the future performance of aircraft; however, no flying qualities requirements exist for Unmanned Aerial Vehicles (UAVs). The intent of flying qualities requirements is to guarantee the safety and operational effectiveness of the aircraft. Flying qualities requirements have been extensively researched and specified for fixed-wing and rotary-wing manned aircraft based on a substantial database of assessments. The critical issue today in flying qualities is how to extend them to pilotless aircraft. A simulation study using an open-source flight dynamics model (JSBSim) was conducted to perform various performance maneuvers and evaluate how well the …

Analysis Of A Modified Equivalent Circuit Model For Lithium-Ion Battery Modules In Cubesats, James J. Liu

Theses and Dissertations

Failure of the electrical power system (EPS) to meet mission requirements is a common problem in nano-size satellites commonly referred to as CubeSats. The motivation for this research stems from the desire to prevent EPS failure through a process of testing and space qualification of components. Utilizing models to predict the behavior of an EPS before it is designed, built, and tested for space can provide critical insight in areas of limitation in performance and survivability. Modeling an entire EPS system is challenging because it requires extensive knowledge of all components and their behavior. This research focuses specifically on the …

Geolocation Of Rf Emitters Using A Low-Cost Uav-Based Approach, Michael A. Magers

Theses and Dissertations

The proliferation of unmanned aerial vehicles (UAVs) in both military and civilian settings has prompted great interest in finding new and innovative ways to utilize these tools. One such application is to locate ground-based radio emitters from a UAV platform. The goal of this research is to study the feasibility of a low-cost (on the order of $1000) UAV geolocation platform. To accomplish this goal, a series of both real-world flight testing and computer simulated scenarios were conducted. Simulations for different sensor uncertainties and approach path scenarios such as loiter and button hook patterns were investigated. Results showed that a …

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• Amazon award to IT’s Russell Thackston

Ray-Based Statistical Propagation Modeling For Indoor Corridor Scenarios At 15 Ghz, Qi Wang, Bo Ai, David W. Matolak, Ruisi He, Xin Zhou

Faculty Publications

According to the demands for fifth-generation (5G) communication systems, high frequency bands (above 6 GHz) need to be adopted to provide additional spectrum. This paper investigates the characteristics of indoor corridor channels at 15 GHz. Channel measurements with a vector network analyzer in two corridors were conducted. Based on a ray-optical approach, a deterministic channel model covering both antenna and propagation characteristic is presented. The channel model is evaluated by comparing simulated results of received power and root mean square delay spread with the corresponding measurements. By removing the impact of directional antennas from the transmitter and receiver, a path …

Forensic Schedule Analysis Of Construction Delay In Military Projects In The Middle East, James W. Forbes

Theses and Dissertations

This research performs forensic schedule analysis of delay factors that impacted recent large-scale military construction projects in the Middle East. The purpose of this study is to understand the most significant causes of project delay and how AFCEC might improve schedule management performance. The methodologies for analysis are adapted from the Professional Practice Guide to Forensic Schedule Analysis, particularly Method 3.7 Modeled/Additive/Multiple Base, or Time Impacted Analysis—Adjusted. The data is gathered from USACE and AFCEC, consisting of Primavera project schedules and project documents from the Resident Management System database. The project delays from two large-scale projects are apportioned as compensable, …

A Comparative Analysis Of Ieee 802.15.4 Adapters For Wireless Range Finding, Andrew P. Seitz

Theses and Dissertations

ZigBee wireless networks have become increasingly prevalent over the past decade. Based on the IEEE 802.15.4 low data rate wireless standard, ZigBee offers low-cost mesh connectivity in hospitals, refineries, building automation, and critical infrastructure. This thesis explores two ZigBee Received Signal Strength Indicator (RSSI)-based rangefinding tool sets used for assessing wireless network security: Z-Ranger and Zbfind. Z-Ranger is a new tool set developed herein for the Microchip Zena Wireless Adapter that offers configurable distance estimating parameters and a RSSI resolution of 256 values. Zbfind is an application developed for the Atmel RZUSBstick with no configurable distance estimating parameters and a …

Multi-Cubesat Deployment Strategies: How Different Satellite Deployment Schemes Affect Satellite Separation And Detection For Various Types Of Constellations And Missions, Scott A. Biehl Jr.

Theses and Dissertations

As economics drive an increased demand for small satellites and, consequently, an increase in the number of satellites deployed per launch, different deployment schemes and their effects on satellite dynamics must be well understood. While there are advantages to deploying multiple satellites at once, users may have trouble with tracking, identifying, and communicating with their satellites. This investigation examines the deployment of eight 3U CubeSats, and the resulting relative motion within a constellation. Both the distance between any two satellites within a constellation and the volume of a polygon encompassing a constellation are used to analyze the satellite dynamics within …

Investigation Into Active Spanwise Camber Deformation On The Lateral Stability And Roll Control Of The X-56a Compared To Conventional Ailerons, Eric T. Yerly

Theses and Dissertations

"This research compares the stability and roll characteristics of an X-56A using AFRL’s Variable Camber Complaint wing technology to actively change wing camber compared to conventional ailerons deflected at set angles. An analysis of the stability and roll characteristics was modeled using a 3-D vortex lattice theory simulation, and that data was compared to wind tunnel testing to verify and validate the model results. Wind tunnel data was collected using 19 inch 3-D printed scale models with wings fabricated with a pre-determined percentage of camber deformation, as well as models with fixed aileron deflections. The full span model changed camber …

A Time-Variant Value-Focused Methodology For Supporting Pre-Acquisition, Brian K. Scheller

Theses and Dissertations

Military operations are dynamic in nature, as time-dependent requirements or adversary actions can contribute to differing levels of mission performance among systems. Future military operations commonly use multi-criteria decision analysis techniques that rely on value-focused thinking (VFT) to analyze and ultimately rank alternatives during the Analysis of Alternatives phase of the acquisition process. Traditional VFT approaches are not typically employed with the intention of analyzing time-variant performance of alternatives. In this research, a holistic approach towards integrating fundamental practices such as VFT, systems architecture, and modeling and simulation is used to analyze time-dependent data outputs of an alternative’s performance within …

Vibrational Analysis Of A 12u Chassis, Daniel G. Miller

Theses and Dissertations

The objective of this research is to characterize how the natural frequencies of AFIT’s CubeSat design can be controlled to meet launch vehicle requirements while increasing the internal and external volume available for payload and bus components as the chassis increases in size. A reliable Finite Element (FE) model is created and validated using NASA’s General Environmental Verification Standards (GEVS) vibrational test on the 12U chassis. The validated FE model proves that current boundary conditions and geometric properties with minimized chassis wall thicknesses to maximize usable internal and external volume maintain a first frequency of the fully loaded 12U chassis …

Electro-Mechanical Characterization Of Carbon Nanotube Sheets In Simulated Space Environments: The Dawn Of “Carbon Spacecraft”, Jacob W. Singleton

Theses and Dissertations

Carbon nanotube (CNT) materials are exciting candidates for spacecraft by virtue of their unprecedented specific mechanical and electrical properties. Analysis in this thesis identifies 14 types of CNT-sheets with distinct variables, and discovers the mechanisms controlling macroscopic properties. Specimen variables include acid treatment, polymer coatings, production method, and combinations. Mechanical testing includes tensile-tests and investigation with scanning electron microscopy and energy-dispersive x-ray spectroscopy. Physical properties testing include electromagnetic interference (EMI) shielding effectiveness (SE) and electrical conductivity. This research also highlights the resilience of CNT-sheets to atomic oxygen and thermal fatigue qualifying them for performance in space. EP CNT-sheets have decreased …

Analysis Of Inpatient Hospital Staff Mental Workload By Means Of Discrete-Event Simulation, Erich W. Maxheimer

Theses and Dissertations

Many process improvement tools have been applied to the healthcare industry to improve safety and efficiency. However, nearly all of these tools have neglected to explicitly quantify mental workload of healthcare providers despite the consensus that it is related to human performance. This research uses the Improved Performance Research Integration Tool (IMPRINT), a discrete-event simulation (DES), to quantify mental workload. Specifically, this research examines staff members in an inpatient unit at the Wright-Patterson Medical Center to detect workload differences between staff, identify trends which lead to high workload demands, evaluate the influence of patient load on mental workload, and test …

Neutron Radiation Effects On Ge And Gesn Semiconductors, Christopher T. O'Daniel

Theses and Dissertations

Two different semiconductor materials received neutron radiation for assessment of radiation damage. The two materials are undoped bulk Ge and epitaxial Ge_0.991Sn_0.009, which is doped heavily with phosphorous. At room temperature, the Ge sample has direct and indirect bandgaps at 0.78 eV and 0.66 eV, respectively. The Ge_0.991Sn_0.009 sample has direct and indirect bandgaps at 0.72 eV and 0.63 eV, respectively. Two samples of each material were exposed to research reactor neutrons, delivering a 1 MeV equivalent neutron fluence of 2.52 × 10¹⁵ n/cm². In order to assess the radiation …

Scientometric Analysis Of Technology & Innovation Management Literature, Kadir Yildiz

Theses and Dissertations

The management of technology and innovation has become an attractive and promising field within the management discipline. Therefore, much insight can be gained by reviewing the Technology & Innovation Management (TIM) research in leading TIM journals to identify and classify the key TIM issues by meta-categories and to identify the current trends. Based on a comprehensive scientometric analysis of 5,591 articles in 10 leading TIM specialty journals from 2005 to 2014, this research revealed several enlightening findings. First, the United States is the major producer of TIM research literature, and the greatest number of papers was published in Research Policy …

Spectroscopic Measurement Of Gas Temperature In Small Internal Combustion Engines, Matthew J. Deutsch

Theses and Dissertations

The Small Engine Research Bench (SERB) was used previously to measure spatially and temporally averaged heat flux, as well as local, instantaneous heat flux at several external locations, for a series of small engines (1 - 10 kW). This investigation obtained time averaged crank angle resolved measurements of the in-cylinder gas temperature using Fourier transform infrared (FTIR) absorption thermometry. The results, coupled with heat flux measurements, will enable the validation or refinement of existing thermal energy loss models.

Orbital Resonances In The Vinti Solution, Laura M. Duffy

Theses and Dissertations

The Vinti Solution offers a more accurate model than the two-body problem as an orbital propagator. Unfortunately, the Vinti solution contains small divisors near orbital resonances in the perturbative terms of the Hamiltonian, which lead to inaccurate orbital predictions. One approach to avoid the small divisors is to apply transformation theory. The methodology of this research is to identify the perturbative terms of the Vinti Solution, perform a coordinate transformation, and derive the new equations of motion for the Vinti system near orbital resonances. The analysis in this research focuses on the 2:1 resonance, which includes the Global Positioning System. …

Improving System Design Through The Integration Of Human Systems And Systems Engineering Models, Michael E. Watson

Theses and Dissertations

The human is a critical aspect of many systems, but frequently there is a failure to properly account for human capabilities and involvement during system design. This inattention results in systems with higher lifecycle costs, decreased user compatibility, and the potential to produce disastrous consequences. This research presents an approach to integrating the human into system models by using two methods: static and dynamic modeling. The static method uses a user-centered design framework to create system- and human-centered models that deconstruct the system and user into their respective components. These models are integrated to create system models that include relevant …

Conceptual Design, Structural Analysis, And Design Space Exploration Of A Vacuum Lighter Than Air Vehicle, Brian C. Cranston

Theses and Dissertations

The research detailed in this study investigates an internal vacuum as well as its optimal structural design, utilizing currently available materials, as an alternative to traditional gases to create and sustain buoyancy in lighter than air vehicles. To date, the consideration of a vacuum lighter than air vehicle has been limited to three sources of literature, the earliest of which dates back to 1663. This study will initially summarize and review this literature. We will then combine finite element analysis, dimensional analysis, design of experiments, and response surface methodology studies to explore the feasibility, and the functional design of a …

Performance Testing Of Various Nozzle Design For Water Electrolysis Thruster, Yuen Liu

Theses and Dissertations

The purpose of this research is to develop new nozzles for the HYDROS^TM thruster, a pulsed chemical thruster, to improve the current flight performance. This research consists of a base line test of the factory nozzle, as well as testing of three 15-degree conical nozzles with different expansion ratios. Experiments were conducted at plenum pressures 30, 40, and 45 psia to ensure the thruster is throttleable. Impulse bit data was collected through measuring the impulse response of each firing using a torsional balance thrust stand. Analysis of the thruster performance included calculations of impulse bit, specific impulse, thrust coefficient, …