Engineering Commons^™

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 …

Hall Effect Thruster Characterization Through Potential, Magnetic, And Optical Measurements, Nicholas L. Hyatt

Theses and Dissertations

Electric propulsion is a promising method for providing ΔV to spacecraft on orbit. In general, much higher I_SPS are obtained compared to their chemical counterparts. Hall thrusters are a subset of electric propulsion with moderately high specific impulse and thrust when compared to other forms of electric propulsion. Even though Hall thrusters have an extensive flight legacy around the world, there are still many unknowns associated with their operation. Experimental research was conducted in AFIT’s Space Propulsion Application Simulation System (SPASS) laboratory, to measure Hall current, plasma potential and visible emission from the 600W Hall thruster in a …

Using Gaussian Mixture Model And Partial Least Squares Regression Classifiers For Robust Speaker Verification With Various Enhancement Methods, Joshua Scott Edwards

Theses and Dissertations

In the presence of environmental noise, speaker verification systems inevitably see a decrease in performance. This thesis proposes the use of two parallel classifiers with several enhancement methods in order to improve the performance of the speaker verification system when noisy speech signals are used for authentication. Both classifiers are shown to receive statistically significant performance gains when signal-to-noise ratio estimation, affine transforms, and score-level fusion of features are all applied. These enhancement methods are validated in a large range of test conditions, from perfectly clean speech all the way down to speech where the noise is equally as loud …

Analysis Of Aggregate Mineralogy Using Libs, Bless Ann Varghese

Theses and Dissertations

The New Jersey Department of Transport (NJDOT) has a vested interest in the determination of the chemical composition and thereby the mineralogy of aggregates. Depending on the mineralogy of an aggregate sample, it may be inappropriate to use for construction and roadwork purposes. Current methods of determining the mineralogy of aggregates are costly in terms of time, money and convenience. As such, there is a desire for the development of an alternative and efficient method for aggregate mineralogical determination in the field.

The focus of this study is to develop a portable system for aggregate analysis in the field and …

Structural Strength Evaluation And Retrofitting Of Hangar Q At Millville Airport, Harshdutta Indradutta Pandya

Theses and Dissertations

Hangar Q was built in Millville, New Jersey as a part of the Home Defense Program of World War II. The airport is now owned and operated by the Delaware River and Bay Authority (DRBA) as the Millville Airport. Hangar Q was a historic nine-bow truss hangar when it was first constructed, standing at 30 feet high, 130 feet wide, and 160 feet deep. It was originally constructed with no side walls and no back wall or front roll-up doors. It was later updated from a completely open design to a closed design. The objective of this study was to …

Preserving Optical Confinement In Pecvd Sio2 Waveguides By Control Of Thin-Film Stress, Steven Jay Hammon

Theses and Dissertations

Researchers at Brigham Young University (BYU) have developed an optical biosensor that can quickly analyze a sample to detect any type of nucleic acid based organism, such as viruses or bacteria. The biosensor's reliability over time is compromised due to water absorbing into the SiO₂ waveguides of the chip. It was hypothesized that keeping the thin-film stress of the waveguides close to zero would slow or stop water absorption from occurring. Completion of this thin-film study relied upon a new plasma enhanced chemical vapor deposition (PECVD) machine and a new 3-D optical profilometer, both of which were installed in …

Karakteristikat E Shtresës Së Epërme Të Asfaltit (Stone Mastic Asphalt), Arbër Misini

Theses and Dissertations

Stone Mastik Asfalti (SMA) ka gjetur përdorim të gjerë në shumë vende si një shtresë sipërfaqësore mjaft e preferuar. Kjo histori e përdorimit të këtij materiali daton qysh para 30 viteve, dhe si çdo produkt tjetër ashtu edhe stone mastik asfalti nevojitet të modifikohet dhe të adaptohet konform materialeve moderne dhe prodhimtarisë, si dhe të përshtatet kushteve të lokacionit përkatës.

Ky punim zhvillon dhe analizon të gjitha karakteristikat e SMA-së si shtresë e epërme sipërfaqësore dhe bënë krahasimin me shtresat nga asfalti i rëndomtë (asfaltbetoni).

Shtresat e epërme të asfaltit (shtresat hargjuese) janë shtresat që i nënshtrohen drejt për së …

Efekti I Hirit Të Furrëlartave Në Beton Dhe Impakti Ambiental I Tij, Ramiz Vokshi

Theses and Dissertations

Hiri fluturues është një produkt i thengjillit të djegur nga stacionet e energjisë termike i cili ka veti të ngjajshme me çimenton dhe veti pozzolonic. Pra hiri, eshte një mbetje e krijuar nga termocentralet duke paraqetiru një shqetësim te madh per mjedisin.

Qëndrueshmëria shpeshhere e pamjaftueshme e çimentos portland ne përforcimin e strukturave të betonit dhe rritja e vëllimit të ndërtimit në dekadat e fundit ka rezultuar në një shterrim të burimeve tona natyrore. Industria e betonit, për shkak të volumit te madh të tij gjate perdorimit, qe është ideale për ekonomine dhe sigurt nevoja per inkorporimin e miliona ton …

The Fresnel Zone Light Field Spectral Imager, Francis D. Hallada

Theses and Dissertations

This thesis provides a computational model and the first experimental demonstration of a Fresnel zone light field spectral imaging (FZLFSI) system. This type of system couples an axial dispersion binary diffractive optic with light field (plenoptic) camera designs providing a snapshot spectral imaging capability. A computational model of the system was developed based on wave optics methods using Fresnel propagation. It was validated experimentally and provides excellent demonstration of system capabilities. The experimentally demonstrated system was able to synthetically refocus monochromatic images across greater than a 100nm bandwidth. Furthermore, the demonstrated system was modeled to have a full range of …

Cloud-Based Analytic Element Groundwater Modeling, Jacob Baird Fullerton

Theses and Dissertations

Managing groundwater resources requires computer modeling software, which in turn brings its own costs in education and usage fees. Although many groundwater modeling programs can be obtained at relatively inexpensive rates the hidden costs of software training remain high in general. What has been done is to make both the software and training available online for free, but this method delegates all responsibility to the users for both accessing the software in addition to learning how to use it properly. In this research the accessibility of groundwater models has been improved upon by creating a web app of an open …

Characterizing Current And Geologic Phosphorus In Utah Lake Sediment Using Field Samples, Laboratory Methods, And Statistical Analysis: Implications For Water Quality Issues, Hani Yousef Abu Hmeidan

Theses and Dissertations

Phosphorus is an essential nutrient for aquatic life forms and plays a major role in the algae blooms that occur in lakes and reservoirs. It is considered a primary limiting nutrient of phytoplankton growth in streams, lakes, and reservoirs. Excess amounts of phosphorous may cause excess growth and biomass of algae. If phosphorus is available in excess, often from sewage and industrial discharges, the high levels in a lake or reservoir can lead to eutrophication. Utah Lake is a shallow, basin-bottom lake in a semi-arid climate with sediments that are thousands of feet thick. Starting 165 years ago, humans have …

An Analytical Model To Predict The Length Of Oxygen-Assisted, Swirled, Coal And Biomass Flames, David Arthur Ashworth

Theses and Dissertations

Government regulations to reduce pollutants and increasing environmental awareness in the power generation industry have encouraged coal power plants to begin firing biomass in their boilers. Biomass generally consists of larger particles which produce longer flames than coal for a given burner. The length of the flame is important in fixed-volume boilers because of its influence on heat transfer, corrosion, deposition, and pollutant formation. Many pulverized fuel burners employ a series of co-annular tubes with various flows of fuel and air to produce a stabilized flame. A variable swirl burner with three co-annular tubes, each of variable diameter, has been …

A Security Evaluation Methodology For Container Images, Brendan Michael Abbott

Theses and Dissertations

The goal of this research is to create a methodology that evaluates the security posture of container images and helps improve container security. This was done by first searching for any guidelines or standards that focus on container images and security. After finding none, I decided to create an evaluative methodology. The methodology is composed of actions that users should take to evaluate the security of a container image. The methodology was created through in-depth research on container images and the build instructions used to create them and is referred to as the Security Evaluation Methodology for Container Images. The …

Common Support Equipment And Its Impact On Aircraft Availability, Jason M. Leighton

Theses and Dissertations

The ability of military aircraft maintenance personnel to prepare aircraft for flight depends not only on the technical ability and availability of replacement parts, but also on access to serviceable support equipment. While the general relationship between support equipment failures and aircraft availability is understood, the struggle to quantify that relationship makes targeted support equipment replacement or quantity authorization increases difficult. Tight budgets and aging equipment further complicate the task of keeping serviceable support equipment assets in the hands of maintainers. We identify key pieces of support equipment which may affect aircraft availability and other metrics and investigate the associated …

A Review Of The Potential Therapeutic Application Of Vagus Nerve Stimulation During Childbirth, Tanya Enderli

Theses and Dissertations

The goal of this research is to show that transcutaneous Vagus nerve stimulation (tVNS) should be investigated as a possible modality for increasing endogenous release of oxytocin during childbirth. There have been many great advances made in the practice of modern obstetrics in the last century. The 1900s saw the discovery, isolation, and subsequent widespread use of the hormone oxytocin as an agent to prevent postpartum hemorrhage and to initiate or quicken labor during childbirth. There are significant risks to the fetus when synthetic oxytocin is used. While the medical administration of oxytocin during labor was being popularized, there was …

Engineering Cell-Free Protein Synthesis Technology For Codon Reassignment, Biotherapeutics Production Using Just-Add-Water System, And Biosensing Endocrine Disrupting Compounds, Sayed Mohammad Salehi

Theses and Dissertations

Cell-free protein synthesis is an emerging technology that has many applications. The open nature of this system makes it a compelling technology that can be manipulated to answer many needs that are unavailable in other systems. This dissertation reports on engineering this technology for: 1) sense codon emancipation for incorporation of multiple unnatural amino acids; 2) expressing a hard-to-express anticancer biotherapeutic and introducing a just-add-water system; 3) a biosensing ligand that interacts with nuclear hormone receptors. Emancipating sense codons toward a minimized genetic code is of significant interest to science and engineering. A promising approach to sense codon emancipation is …

A Reconfigurable Trusted Platform Module, Matthew David James

Theses and Dissertations

A Trusted Platform Module (TPM) is a security device included in most modern desktop and laptop computers. It helps keep the computing environment secure by isolating cryptographic functions and data from the CPU. A TPM is usually implemented with a small microcontroller which is near the main processor. In addition to a microcontroller, it may employ hardware acceleration to assist in cryptographic computations. When vulnerabilities are found, or new algorithms developed, TPMs become obsolete because the hardware accelerators cannot be upgraded. This thesis presents a proof of concept implementation of a TPM on an FPGA. By using an FPGA, the …

Extension Of The Quikscat Sea Ice Extent Data Set With Oscat And Ascat Data, Jordan Curtis Hill

Theses and Dissertations

Polar sea ice measurements are an important contribution to global climate models. Passive and active microwave remote sensing instruments are used to track global trends in polar sea ice growth and retreat from day to day. A scatterometer sea ice extent data set is valuable for comparison with other radiometer data sets and ground based measurements. This scatterometer sea ice record began with the NASA Scatterometer (NSCAT) and continued with the Quick Scatterometer (QuikSCAT) data set. The Ku-band Oceansat-2 scatterometer (OSCAT) is very similar to the Quick Scatterometer, which operated from 1999 to 2009. OSCAT continues the Ku-band scatterometer data …

High-Sensitivity Phased Arrays For Radio Astronomy And Satellite Communications, Junming Diao

Theses and Dissertations

Radio astronomy is used to study stars, galaxies, black holes and gas clouds radiation at radio frequencies. Detecting extremely weak signals from deep space radio sources requires high sensitive feed system associated with large dish antennas. The key figure of merit is survey speed, or the time required to map a region of the sky to a given source flux density. Survey speed is proportional to the frequency bandwidth, the field of view or observable region of the sky, and the squared sensitivity, where sensitivity is related to reflector aperture efficiency and system noise temperature. Compared to the traditional single …

The Development Of A Vertical-Axis Wind Turbine Wake Model For Use In Wind Farm Layout Optimization With Noise Level Constraints, Eric Blaine Tingey

Theses and Dissertations

This thesis focuses on providing the means to use vertical-axis wind turbines (VAWTs) in wind farms as an alternative form of harnessing wind energy in offshore and urban environments where both wake and acoustic effects of turbines are important considerations. In order for VAWTs to be used in wind farm layout analysis and optimization, a reduced-order wake model is needed to calculate velocities around a turbine quickly and accurately. However, a VAWT wake model has not been available to accomplish this task. Using vorticity data from computational fluid dynamic (CFD) simulations of VAWTs and cross-validated Gaussian distribution and polynomial surface …

Mapping Tools For Measuring Gross Motor Function In Conductive Education, Jara’ Nicole Templet

Theses and Dissertations

Cerebral Palsy (CP) is a collection of disorders caused by disturbances in the developing brain before, during, or just after birth that affect the development of movement and posture resulting in limitations in activity. Two of the most widely employed gross motor function classification systems used to classify CP are the Gross Motor Function Measure (GMFM) and the Gross Motor Function Classification System (GMFCS). Despite the wide use of these classification systems, neither is fully sufficient in classifying the gross motor function of a patient with CP. A newer therapy program, Conductive Education (CE) seeks to help children with CP …