Engineering Commons^™

Discovery Of Materials Through Applied Machine Learning, Travis Williams

Theses and Dissertations

Advances in artificial intelligence technology, specifically machine learning, have cre- ated opportunities in the material sciences to accelerate material discovery and gain fundamental understanding of the interaction between certain the constituent ele- ments of a material and the properties expressed by that material. Application of machine learning to experimental materials discovery is slow due to the monetary and temporal cost of experimental data, but parallel techniques such as continuous com- positional gradients or high-throughput characterization setups are capable of gener- ating larger amounts of data than the typical experimental process, and therefore are suitable for combination with machine learning. A …

Modeling Neutron Interaction Inside A 2d Reactor Using Monte Carlo Method, A. S. M. Fakhrul Islam

Theses and Dissertations

Scientists and engineers have been working for many years to develop accurate approaches to analyzing nuclear power reactors using computer codes that closely model the behavior of neutrons in a reactor core. The Monte Carlo simulation method is capable of treating complex geometries with a high level of resolution and fidelity to model neutron interactions inside a reactor core. With the requirement of accurate modeling in reactor physics and dynamics and great innovation of computer technology, Monte Carlo method is becoming an ever more powerful tool and receiving rising attention. In this study, Monte Carlo method is used to model …

Study Of Wire Arc Additive Manufacturing With Aluminum Alloy 2219, Sritam Kumar Dash

Theses and Dissertations

This thesis discusses WAAM (wire arc additive manufacturing) technology using TIG (Tungsten Inert Gas) welding method with aluminum 2219 as the substrate and aluminum 2319 as the filler material. The most important characteristic of this method of manufacturing is very little wastage of material as it does not follow the conventional method of manufacturing where material is removed from a bigger block to finally achieve the desired shape. This method uses a layer by layer approach to build the part. Generally, in additive manufacturing, the production time may vary depending on the type of method used. The material deposition rate …

Wireless Rf Induced Energy Absorption And Heating Of Lanthanum-Nickel Alloy In The Near-Field, Michael Dillon Lindsay

Theses and Dissertations

This thesis will investigate whether and how a synthetic metal-magnetic alloy absorbs enough near-field electromagnetic (EM) radiation for heating. Although resistive elements could be used for indirect heating, a wireless radio frequency (RF) method is explored because of its advantages in its non-intrusive nature and its ability to direct or focus energy within a specific area. For our case, the RF heating process relies on the materials ability to absorb sufficient RF energy due to the induced currents. We expect there to be significant surface resistance due to the conductivity and magnetic permeability of the material and thus heat. This …

Person Identification With Convolutional Neural Networks, Kang Zheng

Theses and Dissertations

Person identification aims at matching persons across images or videos captured by different cameras, without requiring the presence of persons’ faces. It is an important problem in computer vision community and has many important real-world applica- tions, such as person search, security surveillance, and no-checkout stores. However, this problem is very challenging due to various factors, such as illumination varia- tion, view changes, human pose deformation, and occlusion. Traditional approaches generally focus on hand-crafting features and/or learning distance metrics for match- ing to tackle these challenges. With Convolutional Neural Networks (CNNs), feature extraction and metric learning can be combined in …

Development Of A National-Scale Big Data Analytics Pipeline To Study The Potential Impacts Of Flooding On Critical Infrastructures And Communities, Nattapon Donratanapat

Theses and Dissertations

With the rapid development of the Internet of Things (IoT) and Big data infrastructure, crowdsourcing techniques have emerged to facilitate data processing and problem solving particularly for flood emergences purposes. A Flood Analytics Information System (FAIS) has been developed as a Python Web application to gather Big data from multiple servers and analyze flooding impacts during historical and real-time events. The application is smartly designed to integrate crowd intelligence, machine learning (ML), and natural language processing of tweets to provide flood warning with the aim to improve situational awareness for flood risk management and decision making. FAIS allows the user …

Bison Simulation-Based Identification Of Important Design Criteria For U3si2 Fuels With Composite-Monolithic Duplex Sic Cladding, Jacob A. Yingling

Theses and Dissertations

Accident Tolerant Fuels (ATF) require a combination of fuel and cladding which have comparable longevity characteristics to UO2 while improving resistance to radiological release during and after accidents. U3Si2 has been proposed for use in ATF concepts for its high uranium density and high thermal conductivity which provide improved fuel performance. However, some of U3Si2’s material properties are not well understood. One such property, thermal creep of U3Si2, is an important contributing factor to U3Si2’s viability as an ATF. No experimentally derived thermal creep model is published for U3Si2, and previous analyses of compressive thermal creep experimental data lack statistical …

Modeling The Uranium-Silicon Phase Equilibria Based On Computational And Experimental Analysis, Tashiema Lixona Ulrich

Theses and Dissertations

As part of Accident tolerant fuel initiative, the uranium-silicide compound, U3Si2, is under consideration as a potential replacement for conventional uranium dioxide fuel. It is of interest as its higher uranium density of 11.3 g(U)/cm3 compared to 9.7 g(U)/cm3 for UO2 may allow use of more robust, but less neutronically economical fuel cladding. The improved uranium content would not only accommodate the neutronic penalty inherent to certain accident tolerant cladding concepts but also facilitate improved reactor performance with the potential for longer fuel cycles.

The U-Si system has been the subject of various studies that mainly focused on thermophysical properties, …

Adipose Tissue Engineering: A Therapeutic Strategy For The Treatment Of Obesity And Glucose Intolerance, Michael A. Hendley

Theses and Dissertations

Despite available treatment options, the number of people afflicted by type 2 diabetes has steadily risen for decades. Nearly 90% of the diabetic population also suffers from obesity and the link between the two diseases is undeniable. Characterized by rapid expansion of the adipose tissue and improper lipid storage, the mishandling of lipids by adipose tissue promotes the diabetic state. Excess lipids, unable to be properly stored, build up in peripheral tissues promoting insulin resistance and type 2 diabetes. Therapeutic strategies designed to address adipose tissue lipid handling could represent a promising treatment strategy for obesity associated type 2 diabetes. …

Tissue-Specific Roles Of Transforming Growth Factor Beta Ligands In Cardiac Outflow Tract Malformations And Calcific Aortic Valve Disease, Nadia Al-Sammarraie

Theses and Dissertations

Congenital heart defects and adult calcific aortic valve disease are two of the leading causes of morbidity and mortality worldwide. To date, there is no medical cure and surgical intervention is the main option of treatment. The cardiac outflow tract is the major site for these abnormalities, which are triggered by genetic and/or environmental factors that alter development and/or homeostasis. Recently, significant roles of TGFβ signaling in development of cardiovascular disorders have become more evident in humans, however, the specific requirement of individual TGFβ ligands on the pathogenesis of OFT malformations and diseases remains elusive. In the present work, three …

Controlling Weldment And Metallurgical Properties Through Process Control In Rotary Friction Welding, Brandon Scott Boyer Taysom

Theses and Dissertations

Weld quality in the context of process control and internal conditions is studied. Several different alloys are welded including plain carbon steel, high-temperature steels, and several traditional and advanced superalloys. Across all studied weld systems, the following conditions led to stronger welds: higher forces and feedrates, lower temperatures, and moderate or limited upsets. In the best cases, post-weld strengths were nearly equal to basemetal strength. Tradition holds that large and symmetric upsets are necessary for good welds, but this study contradicts that notion. The fundamental requirements for bonding are two sufficiently clean surfaces in intimate contact. Only minimal upset is …

Target Detection In Heterogeneous Clutter With Low Resolution Radar, Kyle G. Stankowski

Theses and Dissertations

This thesis develops a framework for SAR target detection and super-resolution in low-resolution environments. The primary focus in this research is the background clutter heterogeneity that often accompanies low range and cross-range resolutions. A corrective model which accounts for clutter replacement is developed to define the detection and false alarm rates of the detector more accurately than a traditional model in which the radar return from the target supplements the existing clutter. In a heterogeneous clutter cell, the clutter replacement model leverages the different scattering distributions among the individual clutter types to generate a probability distribution function for the areas …

Adaptive-Hybrid Redundancy For Radiation Hardening, Nicolas S. Hamilton

Theses and Dissertations

An Adaptive-Hybrid Redundancy (AHR) mitigation strategy is proposed to mitigate the effects of Single Event Upset (SEU) and Single Event Transient (SET) radiation effects. AHR is adaptive because it switches between Triple Modular Redundancy (TMR) and Temporal Software Redundancy (TSR). AHR is hybrid because it uses hardware and software redundancy. AHR is demonstrated to run faster than TSR and use less energy than TMR. Furthermore, AHR allows space vehicle designers, mission planners, and operators the flexibility to determine how much time is spent in TMR and TSR. TMR mode provides faster processing at the expense of greater energy usage. TSR …

Enabling Mobile Neutron Detection Systems With Clyc, Matthew C. Recker

Theses and Dissertations

Cs₂LiYCl₆:Ce³⁺ (CLYC) has the desirable property of being sensitive to both gamma rays and neutrons while producing waveforms suitable for pulse shape discrimination (PSD) to determine which radiation was detected. This dissertation examines the behavior of CLYC to support its further development for mobile and portable applications. First, the feasibility of performing PSD with CLYC and an inexpensive data acquisition system was examined. This system was able to clearly distinguish both events with a figure of merit of 1.42. Next, the performance of a SiPM was compared to a traditional PMT. Analysis showed that the …

The Impact Of Patient-Specific Vascular Structure On Localized Cooling In The Human Heart, Nathan Paul Spangenberg

Theses and Dissertations

Acute Myocardial Infarction (AMI) is the leading cause of worldwide death and disability, and approximately 720,000 Americans will experience an AMI in 2018. Studies have shown that rapid hypothermia therapy (<35°C) before reperfusion in patients with AMI can reduce infarct size by 37%. Localized therapeutic hypothermia has proven the potential to cool heart tissue rapidly following AMI, 3°C in 5 minutes. Using Materialise Mimics digital imaging software and the finite volume method we analyzed temperature distributions in six patient-specific left main coronary artery (LMCA) models. A mock circulatory loop was used to determine the exiting temperatures of a standard 7 Fr catheter to feed into our model with flow rates ranging from 29.2 ml/min to 68.85 ml/min. Our work showed that therapeutic hypothermia (TH) temperatures were evident at the outlets of three out of all six heart models, which varied in each left anterior descending (LAD) and left circumflex (LCX) artery depending on flowrate. Results of this study indicate that biovariability in patient-specific vascular structures significantly impacts therapeutic hypothermia (TH) treatment methods. These results indicate that further research is needed to examine more accurate physiological effects, such as pulsatile flow and vessel wall thickness. Future models will be used to provide insight to guide more efficient TH device designs and operation parameters to optimize patient outcomes following AMI.

A Study Of Onboarding And Turnover Mediating Variables In U.S. Air Force Officers, Brett S. Bowers

Theses and Dissertations

Employee retention, while always a concern in the workplace, has become a greater challenge for organizations in recent years. Today’s working class has displayed a propensity to change jobs more rapidly than previous generations, exacerbating not only turnover rates but also the costs associated with them (Frankel, 2016). This challenge is especially relevant to the United States Air Force, which has experienced difficulty retaining young officers in recent years. The problems resulting from this voluntary turnover are exceedingly impactful to the military command structure, as senior leaders must work their way up from the lowest ranks. As such, the Air …

Image Based Recognition Of The Monuments In Prizren, Annea Futko

Theses and Dissertations

Image classification application has recently been covering a high number of research fields. In the other hand as the performance of the mobile devices is being updated day by day, the implementation of image recognition algorithms in them, is not only being trendy but very helpful in everyday tasks. With the automatic monument recognition, visiting a city is easy and fun. This application recognizes the captured monument, gives useful information and describes that particular landmark. In this thesis there are used four historical monuments of the city of Prizren, Kosovo. The images where taken specially for the research from the …

Teknologjia E Te (Turbinave Me Erë ) Dhe Lidhja Me Rrjetin Elektrik Shpërndarës, Rron Lenjani

Theses and Dissertations

Një ndër faktorët kryesorë të zhvillimit ekonomik të një vendi dhe ngritjes së mirëqenies së shoqërisë padyshim se është siguria e furnizimit me energji. Furnizimi me energji elektrike në Kosovë mbështetet pothuajse plotësisht në energjinë e prodhuar nga termocentralet (97%), përkatësisht Kosova për përmbushjen e nevojave të veta energjetike mbështetet ekskluzivisht në linjit, e kjo falë rezervave enorme që disponon vendi ynë. Megjithatë rezultatet e këtij sektori lënë për të dëshiruar, gjë e cila ndërlidhet me ekonominë e varfër të vendit. Sigurimi i furnizimit të qëndrueshëm, cilësor, të sigurtë dhe të pandërprerë me energji elektrike është një prej kushteve kryesore …

Gjenerimi I Energjisë Elektrike Me Sistemin Pv Për Konsumatorë Të Vegjël (5kw), Ferki Hyseni

Theses and Dissertations

Energjia është një ndër konceptet që dominon botën moderne. Ajo ka ndikimin bazë në shumë aspekte të jetës sonë, prandaj është tejet e rëndësishme t’i kushtohet rëndësi e veqantë kësaj tematike. Një ndër faktorët kryesorë të zhvillimit ekonomik të një vendi dhe ngritjes së mirëqenies së shoqërisë padyshim se është siguria e furnizimit me energji. Furnizimi me energji elektrike në Kosovë mbështetet pothuajse plotësisht në energjinë e prodhuar nga termocentralet (97%), përkatësisht Kosova për përmbushjen e nevojave të veta energjetike mbështetet ekskluzivisht në linjit, e kjo falë rezervave enorme që disponon vendi ynë. Megjithatë rezultatet e këtij sektori lënë për …

Aplikimi I Kallëpeve Në Ndërtimtari, Blend Humolli

Theses and Dissertations

Bazuar në faktin se betoni është një nga materialet më të përdorua në botën moderne, dhe kombinimi i tij me armaturë është pothuajse i pazëvendësueshëm në ndërtimin e strukturave, të paktën deri më tani, atëherë pashmangshmërisht se në ndërtimin e strukturave të tilla shfaqet nevoja e avancimit të kallëpeve. Për ti kuptuar më mirë këto sisteme të avancuara të kallëpimit duhet të bëhen hulumtime dhe studime të kohë pas kohëshme, në mënyrë që i tërë procesi i ndërtimit të zhvillohet njëkohësisht. Pra është një lidhje zingjirore e cila nuk duhet të shkëputet asesi. Pikërisht për këtë qëllim është bërë edhe …

Vetitë E Agregateve Dhe Përdorimi I Tyre Si Komponente E Betonit, Laureta Musliu

Theses and Dissertations

Ky punim ka si qëllim të jap një përshkrim të hollësishëm dhe më të qartë për materialin ndërtimor-Agregatin. Duke marrë thelbin nga literatura dhe publikime të ndryshme kamë punuar temën me titullin ‘’ Vetitë e Agregateve dhe Përdorimi i Tyre si Komponente e Betonit’’.

Me anë të këtij punimi individual kamë bërë përpjekje që të krijojë një udhëzues me një strukturë të përmbledhur duke treguar karakteristikat dhe përdorimin e agregateve si njërin prej komponentëve kryesor me përqindjen ( % )më të madhe në beton.

Për të njohur më mirë Agregatet duhen njohur vetitë e tyre të cilat janë në pajtueshmëri …

Shtresat E Asfaltit Në Konstruksione Rrugore, Kastriot Maliqaj

Theses and Dissertations

Ky punim kryesisht përbëhet nga mbledhja dhe shqyrtimi i literaturave të ndryshme që ndërlidhen me punimet e ndërtimin e infrastrukturës rrugore. Në shtjellimin e kësaj teme të punimit të diplomës jam shërbyer me metodën e analizës kërkimore dhe me metodën e hulumtimit, softverve të ndryshëm.

Kërkesat e komunikacionit rrugor për rrugët e ndërtuara dhe përshtatura ndaj kushtev për makina të shpejta dhe të rënda motorike, me nivel të madh shërbimi, shkallë sigurie dhe qëndrueshmëri të planifikuar, si dhe hulumtimet e deritanishme eksperimentale në fushën e teknologjisë për prodhimin e shtresave të asfaltit, në katër dekadat e kaluara kishin dhe Akoma …

Investigations Of Point Defects In Kh2Po4 Crystals Using Ab Initio Quantum Methods, Tabitha E. R. Dodson

Theses and Dissertations

Potassium dihydrogen phosphate (KH₂PO₄, or commonly called KDP) crystals can be grown to large sizes and are used for many important devices (fast optical switches, frequency conversion, polarization rotation) for high powered lasers. The nonlinear optical material has a wide intrinsic transparency range. Intrinsic point defects are responsible for several short-lived absorption bands in the visible and ultraviolet regions that affect high-power pulsed laser propagation. The primary intrinsic defects have been experimentally detected in KDP using electron paramagnetic resonance (EPR) experiments. The defect models established thus far include (i) self-trapped holes, (ii) oxygen vacancies, and (iii) …

Effects Of Carbon-Based Ablation Products On Hypersonic Boundary Layer Stability, Olivia S. Elliott

Theses and Dissertations

Hypersonic vehicles require an accurate prediction of the transition of the boundary layer for the design of the thermal protection system due to the high heating rates under turbulent flow. Many thermal protection systems are carbon-based and introduce new species, specifically CO₂, into the boundary layer flow which are known to dampen the instabilities that lead to transition for hypersonic vehicles. A Computation Fluid Dynamics study was accomplished examining the concentration of CO₂ required to impact boundary layer transition over both sharp and blunt cones. These results were used in conjunction with air-carbon ablation models models to …

Investigating Inducer Performance Over A Wide Range Of Operating Conditions, David Tate Fanning

Theses and Dissertations

Inducer performance is investigated for a variety of inducer geometries operating at multiple flow conditions using computational fluid dynamics. Inducers are used as a first stage in turbopumps to minimize cavitation and allow the pump to operate at lower inlet head conditions. The formation of inlet flow recirculation or backflow in the inducer occurs at low flow conditions and can lead to instabilities and cavitation-induced head breakdown. Backflow formation is often attributed to tip leakage flow. The performance of an inducer with and without tip clearance is examined. Removing the tip clearance eliminates tip leakage flow; however, backflow is still …

A Comparison Of Lithium-Ion Cathode Vertical Homogeneity As Influenced By Drying Rate And Drying Method, Alexander Jay Smart

Theses and Dissertations

During lithium-ion battery electrode fabrication, slurry drying conditions influence the resulting microstructure of electrodes. It has been found that the drying conditions can result in non-uniform cathode microstructures and material distributions. Accelerated drying, for example, is widely assumed to cause the binder in an electrode to migrate within the slurry, which can contribute to adhesion failure, and ultimately capacity fade and reduced battery life. While there are some conflicting studies regarding the aspects of accelerated drying that cause binder migration, there is not a widely used standard metric for measuring the gradient of binder across the thickness of an electrode. …

Autonomous And Resilient Management Of All-Source Sensors For Navigation Assurance, Juan D. Jurado

Theses and Dissertations

All-source navigation has become increasingly relevant over the past decade with the development of viable alternative sensor technologies. However, as the number and type of sensors informing a system increases, so does the probability of corrupting the system with sensor modeling errors, signal interference, and undetected faults. Though the latter of these has been extensively researched, the majority of existing approaches have constrained faults to biases, and designed algorithms centered around the assumption of simultaneously redundant, synchronous sensors with valid measurement models, none of which are guaranteed for all-source systems. This research aims to provide all-source multi-sensor resiliency, assurance, and …

Nondestructive Electromagnetic Characterization Of Perfect-Electric-Conductor-Backed Uniaxial Materials, Adam L. Brooks

Theses and Dissertations

As the use of anisotropic materials in electromagnetic applications continues to proliferate, it becomes increasingly important to develop non-destructive evaluation methods for those materials in their installed configuration. In many applications, these materials are permanently affixed onto conducting bodies to reduce unwanted reflections, making it impossible to collect S₂₁ or S₁₂ transmission measurements as used in many techniques based on the well-known Nicolson-Ross-Weir algorithm. It also makes it impractical to reorient the sample to collect orthogonal measurements aligned with the optical axes of the anisotropic material. The goal of this research is to develop a two-reflection coefficient measurement …

Digital Holography Efficiency Experiments For Tactical Applications, Douglas E. Thornton

Theses and Dissertations

Digital holography (DH) uses coherent detection and offers direct access to the complex-optical field to sense and correct image aberrations in low signal-to-noise environments, which is critical for tactical applications. The performance of DH is compared to a similar, well studied deep-turbulence wavefront sensor, the self-referencing interferometer (SRI), with known efficiency losses. Wave optics simulations with deep-turbulence conditions and noise were conducted and the results show that DH outperforms the SRI by 10's of dB due to DH's strong reference. Additionally, efficiency experiments were conducted to investigate DH system losses. The experimental results show that the mixing efficiency (37%) is …

Effects Of Infiltration Temperature, Time, And Gas Flow Rate On Material Properties Of Carbon Infiltration Carbon Nanotubes, Shane Dirk Sypherd

Theses and Dissertations

This work characterizes the material properties of carbon infiltrated carbon nanotube (CI- CNT) structures. The impacts of temperature, time, and hydrogen flow rates on the material prop- erties of modulus of elasticity and strength are examined and compared. Carbon infiltration levels are assessed through the use of SEM images to determine which parameters give the highest level of infiltration. Through the use of SEM, carbon capping is observed on samples infiltrated for longer times at 900 and 950◦ C, suggesting that the samples are not being infiltrated during the entire desired infiltration period at these temperatures. The highest material properties …