Engineering Commons^™

Analysis Of Portable Charging Systems For Mobile Devices Utilizing Today's Technology, Dylan Ashley

Electrical Engineering Undergraduate Honors Theses

With the progression of technological advances, electronic devices are becoming increasingly smaller while simultaneously becoming increasing powerful. Consumer demand for a cheaper, longer lasting battery life challenges today’s engineers to continually develop a battery and its circuitry with increasing efficiency without compromising performance. Developing an affordable, efficient external battery pack has been the marketable solution, but the question is whether or not the existing external battery packs available are meeting the wants and desires of the end consumer. The answer is partially in that my research confirms that the current solution is not ideal; however, efficiency has been increased as …

Comparison Of Low-Temperature Co-Fired Ceramic And Direct Bonded Copper For Single Ended Primary Inductance Topology, Kristopher Cody Johnson

Electrical Engineering Undergraduate Honors Theses

This work examines the thermal dissipation characteristics of Low-Temperature Co-fired Ceramic (LTCC) and Direct Bonded Copper (DBC) with the implementation of a Single Ended Primary Inductance Converter (SEPIC) topology. The advantages and disadvantages of the two substrates will be explored in addition to a description of the design and control of the SEPIC. It will be shown that the DBC implementation is superior with regards to thermal dissipation, but that LTCC has advantages in high- density packaging, RF applications, and embedded components. These substrates and converters provide many advantages in industrial applications that include automotive and grid level implementations. Additional …

Maximum Power Point Tracking And Solar Power For Developing Countries Around The World, Christopher M. Plate

Electrical Engineering Undergraduate Honors Theses

Renewable energy is becoming increasingly important as more and more countries become industrialized. Using solar power as opposed to fossil fuels and coal is becoming cheaper and easier to access throughout the world, yet there are still efficiency hurdles to be overcome. Designing a cheap, easily modifiable and reparable Maximum Power Point Tracker would be a stepping stone to bringing solar power to remote parts of the globe. Once designed and made portable, these devices could be distributed throughout developing countries to enhance renewable energy output. An Arduino-based tracker was chosen for ease of use and access. This base also …

Object Tracking Through The Use Of Color Hue Image Processing, Zachary R. Sabey

Electrical Engineering Undergraduate Honors Theses

Many industrial and commercial applications today are beginning to use autonomous systems to increase productivity and cut costs in production and manpower. Most of these applications are only semi autonomous; they still need assistance from a human to either start up or receive continual instructions. With the improvement of image processing techniques, camera processing capabilities and more efficient vehicles, a new wave of fully autonomous vehicles can be implemented. A simple system that uses a dedicated image processor connected to an RC vehicle can be developed to provide an example for the new techniques currently available. The Pixycam, a dedicated …

Ua66 Ogden College Of Science & Engineering Newsletter, Cheryl Stevens, Dean

Ogden College of Science & Engineering Publications

No abstract provided.

Improving Connectivity Between Members And Alumni Of Alpha Pi Mu, Ben Patrick Buell, Shannon Elizabeth O'Keefe

Industrial and Manufacturing Engineering

The purpose of this project was to solve the problems of a lack of connectivity between the current members and alumni of Alpha Pi Mu, as well as the lack of incentives for prospective members to join the club. These problems were solved by creating a website that allowed current members to be able to view the complete work experiences of alumni and provided a way to reach out to those alumni directly to network with them. The agile project management system was used to develop the website and helped to successfully complete all of our design requirements listed in …

A Case Study Of Multiple-Use Finish Electrodes For Die-Sinking Edm, Troy A. Robertson

Masters Theses & Specialist Projects

This study examines the use of one finishing electrode to finish multiple dies without remachining the electrode. The multiple-use electrode finishing experiment in this study addresses technology in the die-forging industry. Methods of manufacturing spherical straight bevel forge gear dies have relied on die-sinking Electrical Discharge Machining (EDM) practices that showed great potential for advancement. The focus of this study is solely on the improvements of electrode use in EDM finishing-processes. The surface finish quality itself is not an area of concern other than maintaining that it does not diminish. The focused concern is maximizing the process by using one …

Characterization Of Microstructure And Property Evolution In Advanced Cladding And Duct: Materials Exposed To High Dose And Elevated Temperature, Janelle P. Wharry

Materials Science and Engineering Faculty Publications and Presentations

Designing materials for performance in high-radiation fields can be accelerated through a carefully chosen combination of advanced multiscale modeling paired with appropriate experimental validation. The studies reported in this work, the combined efforts of six universities working together as the Consortium on Cladding and Structural Materials, use that approach to focus on improving the scientific basis for the response of ferritic–martensitic steels to irradiation. A combination of modern modeling techniques with controlled experimentation has specifically focused on improving the understanding of radiation-induced segregation, precipitate formation and growth under radiation, the stability of oxide nanoclusters, and the development of dislocation networks …

The Implications Of Self-Driving Cars On Insurance, Amanda Lobello

Honors Projects in Mathematics

Self-driving cars, also known as autonomous vehicles, are being researched and tested by automakers, technology industry leaders, and other institutions. Lawmakers and politicians are discussing the legislation that will affect the fate of such technology. Primary benefits include safety, mobility, free time, less traffic, and green effects. However, there are also obstacles to the implementation of self-driving vehicles including consumer acceptance, legal liability, and cost. With the potential shift in responsibility from driver to automaker, rating factors for insurance may change, weighing more heavily on the model of the car as a factor. The fate of auto insurance is in …

Tweetement: Pseudo-Relevance Feedback For Twitter Search, Kanatbay Bektemirov

Computer Science and Computer Engineering Undergraduate Honors Theses

Microblogging platforms such as Twitter let users communicate with short messages. Due to the messages’ short content and the users’ tendency to type short queries while searching, it is particularly challenging to locate useful tweets that match user queries. The fundamental problems of word mismatch due to ambiguity are especially acute. To solve this problem, this thesis explores and compares multiple automatic query expansion methods that involve the most frequent hashtags and keywords. We built a Web service that provides real-time Twitter Search results incorporating automatic query expansion. Six pseudo-relevance feedback methods were studied and the numbers indicate that results …

Fusion Of Short-Mid Wavelength Infrared Image And Long Wavelength Image Using Discrete Wavelet Transform For Image Quality Enhancement, Rocky Hedrick

Electrical Engineering Undergraduate Honors Theses

Infrared technology advancements have led to an expansive set of infrared applications in both the private and public sectors. New materials and manufacturing techniques have continued to reduce the cost while improving the quality of infrared cameras, but the cost is still high when compared to the cost versus quality of visible light spectrum cameras. Innovative image processing techniques can be implemented to help bridge this gap between the cost and quality of infrared cameras. The goal of this research is to improve the overall quality of infrared imaging by fusing short-mid wavelength infrared images and long wavelength images of …

Resonant Spectra Of Metal Nanotoroids Of Various Sizes, Huong Quynh Tran

Electrical Engineering Undergraduate Honors Theses

Nowadays, the manipulation of light by using metallic nanostructures has wide applications in photonics, optoelectronics and energy conversion. Along with other universities all over the world, the University of Arkansas is researching on nano-antennas’ design, fabrication and applications. Current research in Dr. El-Shenawee’s Terahertz Imaging and Spectroscopy Computational Electromagnetics Group, has computationally investigated the behaviors of plasmonic nanostructures by using the commercial finite element electromagnetic solver Ansys® HFSS. This work reproduced the previous work of spectral absorption enhancement of infinite and finite arrays of silver and gold nanotoroids with sizes of the inner radii: 13nm – 21nm, while outer radius …

Magnetic Amplifiers For Voltage Regulation Applications, Casey Morgan O'Grady

Electrical Engineering Undergraduate Honors Theses

The purpose of this thesis is to present research on magnetic amplifiers and to discuss how magnetic amplifiers are useful in voltage regulation applications. Beginning with a background in magnetics and magnetic properties, this thesis outlines the importance of the B-H curve and explains how to simulate the B-H curve of a saturable inductor using LtSpice. Furthermore, two saturable inductors can be aligned in antiparallel to create a magnetic amplifier. The theory of magnetic amplifiers is dated, but its simplistic design has benefits for modern applications. The magnetic amplifier acts as a variable impedance switch where a small amount of …

Design Of Integrated Current Reference Circuits For A 180-Nanometer Bicmos Silicon Process, Timothy Max Megee

Electrical Engineering Undergraduate Honors Theses

The goal of this thesis is to provide design analysis, simulation results, and physical layout structure for three current references that are to be physically fabricated in a 180- nanometer BICMOS silicon process. The report briefly discusses the need for voltage and current references in analog circuit applications, before zooming in to examine three topologies being tailored to the needs of an integrated solar micro-inverter system. These topologies are: proportional to absolute temperature (PTAT), complementary to absolute temperature (CTAT), and constant across temperature (Constant) bias circuits. First, each topology is designed schematically to meet the needs of the micro-inverter system. …

Coreless Planar Transformer Using Low-Temperature Co-Fired Ceramics For Isolated Gate Driver Applications, Matthew W. Feurtado

Electrical Engineering Undergraduate Honors Theses

The aim of this thesis project is to design a signal isolation transformer for gate driver applications using coreless planar transformers (CPT) on a low-temperature co-fired ceramic (LTCC) substrate. To achieve this goal a modulator-demodulator circuit will be selected from several existing designs and an isolation transformer will be designed as a CPT to produce a high frequency high temperature signal isolation for gate driver applications in switching converters, audio drivers, and motor drives. Several designs for coreless planar transformers will be evaluated and tested, and the results will be compared to the theoretical performance obtained from SPICE models for …

Mobile Health Sensing With Smart Phones, Abby Logan Wise

Electrical Engineering Undergraduate Honors Theses

Depression is a serious mental condition affecting many Americans and people across the world. Postpartum depression is a form of depression affecting women who have recently gone through childbirth. Postpartum depression can have serious symptoms that may affect not only the mother, but her newborn as well. Early detection of these symptoms is of critical importance to the welfare of the mother and her child. Many medical professionals express the need for postpartum screening being that treatment has proven to be very effective. This project aims to make early symptom detection convenient and reliable for mothers with newborns. This will …

A Study On The Micro Electro-Discharge Machining Of Aerospace Materials, Mychal-Drew Moses

Masters Theses & Specialist Projects

Electrical Discharge Machining (EDM) is a non-traditional machining process that uses hundreds of thousands of minute electrical sparks per second to machine any electrically conductive material, no matter the hardness or how delicate it is. EDM allows a much greater range of design possibilities, unconstrained from the traditional machining processes, in which material is removed mechanically by either rotating the cutting tool or the work piece. Shapes that were impossible to machine by any other method, such as deep, precision, square holes and slots with sharp inside corners, are readily produced. It provides accurate geometries in high- aspect ratio holes …

Improved Methods For Identifying, Applying, And Verifying Industrial Energy Efficiency Measures, Andrew Chase Harding

Graduate Theses and Dissertations

Energy efficiency is the least expensive source of additional energy capacity for today's global energy expansion. Energy efficiency offers additional benefits of cost savings for consumers, reduced environmental impacts, and enhanced energy security. The challenges of energy efficiency include identifying potential efficiency measures, quantifying savings, determining cost effectiveness, and verifying savings of installed measures. This thesis presents three separate chapters which address these challenges. The first is a paper presented at the 2014 industrial energy technology conference (IETC) that details a compressed air system project using the systems approach to identify cost effective measures, energy intensity to project savings, and …

Laboratory Comparison Of Full Depth Reclamation Stabilization Techniques Using Arkansas Field Materials, Chase Aaron Henrichs

Graduate Theses and Dissertations

Full depth reclamation (FDR) is a flexible pavement recycling technique that has not been explored in the state of Arkansas. FDR is unique in that it incorporates the entire flexible pavement section as well as a predetermined portion of the underlying base and sub-base materials with a stabilizer to create a new, stronger stabilized base course. Common stabilization techniques include the addition of asphalt emulsion, asphalt foam, or cement. Using the North Carolina emulsion FDR mix design, the Wirtgen foam FDR mix design, and the Portland Cement Association cement FDR mix design, field materials from four Arkansas highways in the …

Biofilm-Related Materials As Total N-Nitrosamine (Tono) Precursors And Hydroxylamine-Based Interferences In Tono And N-Nitrosodimethylamine (Ndma) Measurements, David Allen Meints

Graduate Theses and Dissertations

In this study, a chemiluminescence-based total N-nitrosamine (TONO) assay was adapted to include a solid-phase extraction (SPE) step to assess the role of biologically derived materials as N-nitrosamine precursors. Methanol was determined to be a suitable solvent for the SPE-TONO assay, with N-nitrosodimethylamine (NDMA) losses estimated to be 30% by SPE alone and an additional 15% from concentration of the methanol extracts by N2-gas blowdown. Three biofilm-derived materials - poly-N-acetylglucosamine (PNAG), Pseudomonas aeruginosa, and tryptophan - were individually chloraminated and dose-response relationships were observed with the SPE-TONO assay, indicating biofilm are potential N-nitrosamine precursors. The role of hydroxylamine - a …

Comparing Layer Types For The Use Of Mepdg For Fdr Design, Sadie Smith

Graduate Theses and Dissertations

While Full Depth Reclamation (FDR) has many potential cost and environmental benefits, especially over the lifetime of the pavement, it is necessary to be able to ensure that the recycled pavement will perform adequately. One way in which this can be accomplished is understanding how to best complete the structural design of FDR pavements. Because FDR is a combination of several different layers of material pulverized, mixed, stabilized and re-compacted, it does not fit neatly into any of these predetermined types of materials considered by the Mechanistic Empirical Design Guide (MEPDG). Current practice is to treat FDR as an unbound …

Three Dimensional Simulations Of Tornado Sheltering Effect Of Man-Made Structures, Piotr Gorecki

Graduate Theses and Dissertations

A three dimensional computational fluid dynamics (CFD) model was utilized to investigate tornado-like vortex interactions with wide man-made structures. The tornado-like wind profile was approximated using Rankine vortex model. By utilizing the CFD model, it was explained why tornadoes exhibit less damage on leeward side of large structures. During the preliminary stage of this study, a perpendicular vortex-prism interaction was analyzed. The prism height and the length were equal to the vortex core radius. The prism was also 12 times wider than the vortex core radius. During the vortex-prism interaction, the near-ground portion of the vortex was blocked by the …

Amount Of Uncertainty In The Methods Utilized To Design Drilled Shaft Foundations, Morgan Race

Graduate Theses and Dissertations

In 2001, load and resistance factor design (LRFD) for deep foundations was required by the American Association of State Highway and Transportation Officials (AASHTO). Following implementation of LRFD, localized calibration of resistance factors using data from the states of Colorado, Florida, Kansas, Louisiana/Mississippi, Missouri allowed these states to utilize higher resistance factors during design. However, characterizing the uncertainty in the design of DSF, regarding the geotechnical investigation methods and the utilized software programs, higher values of resistance factors may be calibrated to more efficiently design DSF with the same level of reliability.

Three test sites within the state of Arkansas, …

Characterization Of Nano-Porous Si-Cu Composites To Enhance Lubricant Retention Impacting The Tribological Properties Of Sliding Surfaces, Julius Sheldon Morehead

Graduate Theses and Dissertations

As the expectations for modern machinery's tribological and thermal performances continue to rise, the retention of lubricant on the contact surfaces of their sliding components becomes an increasingly important issue. Friction and wear cause heat-related failures which lead to catastrophic damage to machinery. Evaporation of a lubricant's volatile constituents as well as lubricant migration leads not only to a reduction in lubricant quantity but also in its quality, thus facilitating component failures. In order to enhance component reliability, the surface should incorporate features that actively retain lubricants. The unique properties of nano-porous topographies such as their high surface area-to-volume ratio …

Development Of Best Management Practices For Turbidity Control During Rainfall Events At Highway Construction Sites Using Polyacrylamide, Joanne Johnson

Graduate Theses and Dissertations

In 2009, the United States Environmental Protection Agency (EPA) promulgated a national turbidity standard for runoff water leaving highway construction sites at 280 nephelometric turbidity units (NTU). Meeting this standard can be challenging as turbidities of runoff waters can exceed 15,000 NTU. The objective of this research was to assess polyacrylamide (PAM), a coagulant aid used in water treatment, to help meet the EPA turbidity regulation. Twelve commercially available PAM types were studied, selected on the basis of charge type (cationic, nonionic, anionic), charge density (0-100%), and molecular weight (0.1-28 Mg mol-1). Jar tests were conducted with runoff waters from …

Measurement Of Transfer And Development Lengths Of 0.7 In. Strands On Pretensioned Concrete Elements, Canh Ngoc Dang

Graduate Theses and Dissertations

The implementation of 0.7 in. (17.8 mm), Grade 270 (1860), low-relaxation prestressing strands in construction is slow regardless of its advantages over the use of 0.6 in. (15.2 mm) and 0.5 in. (12.7 mm) strands. The limited research data and unavailable design guidelines partially account for the slow utilization. This study measured transfer and development length, and evaluated applicable strand spacing of 0.7 in. (17.8 mm) prestressing strands for 24 pretensioned concrete beams. Each beam contained one prestressing strand or two prestressing strands placed at spacing of 2.0 in. (51 mm). The beams were fabricated with high strength, conventional concrete …

Achieving Enhanced Treatment Of Produced Fluids Using Ozone, Hydrogen Peroxide And Electrochemical Oxidation: Full Scale Evaluations, Jamar Willis Blackmon

Graduate Theses and Dissertations

The main focus of the present work was to expand the existing knowledge in using an advanced oxidation process for produced water treatment. Produced water is a phrase used in the oil and gas industry to describe water that is produced as a waste byproduct together with oil and gas. Historically produced water was pumped down disposal wells as a waste product. Due to increasing demand, limited supply and stricter regulation on fresh water sources, exploration and production companies have been compelled to recycle produced waters in many parts of their operations around the world.

Produced water quality varies dramatically …

Vcare: A Personal Emergency Response System To Promote Safe And Independent Living Among Elders Staying By Themselves In Community Or Residential Settings, Priyankar Bhattacharjee

Department of Computer Electronics and Engineering: Dissertations, Theses, and Student Research

‘Population aging’ is a growing concern for most of us living in the twenty first century, primarily because many of us in the next few years will have a senior person to care for - spending money towards their healthcare expenditures AND/OR having to balance a full-time job with the responsibility of care-giving, travelling from another city to be with this elderly citizen who might be our parent, grand-parent or even community elders. As informal care-givers, if somehow we were able to monitor the day-to-day activities of our elderly dependents, and be alerted when wrong happens to them that would …

Effective Antisense Design Using An Ensemble Of Energetically Sub-Optimal Secondary Mrna Structures, Andrea M. Divenere

University Scholar Projects

There is a current deficit of effective therapies against bacterial infection. Many strategies seek using small molecules to target the infectious pathogen. One approach involves direct manipulation of the pathogen at the RNA level. Messenger RNA (mRNA) is a genetic transcript that encodes the fundamental instruction for protein production. Inhibiting mRNA translation effectively prevents protein synthesis.

The therapeutic agent must physically access mRNA to effectively block its message from being read. A technique has arisen where a complementary nucleic acid binding strand, called antisense, is generated to impede protein synthesis. An issue in creating effective antisense is finding mRNA target …

The Development And Evaluation Of A Method For Understanding The Impact Of Transmission Loss On The Overall Noise Attenuation Of Finite Barriers, Ashwin Arvind Upasani

Graduate Theses - Mechanical Engineering

The purpose of this study is to evaluate the impact of transmission loss on the overall noise reduction obtained from finite barriers. The noise attenuation ability of barriers is understood to be a consequence of sound waves diffracting around their edges. Although the presence of transmission loss is acknowledged, its significance in affecting noise attenuation is usually not considered a priority in barrier design. This study incorporates the Fresnel Number concept for predicting theoretical insertion loss of a finite barrier and compares these predictions to experimental observations. The experiments performed in this study offer a method to isolate the transmission …