Engineering Commons^™

The Role Of Inter-Particle Behavior In Iron Oxide Nanoparticle Induction Heating, Hayden Seth Carlton

Graduate Theses and Dissertations

Due to their multi-functional nature, iron oxide nanoparticles present themselves in a myriad of scientific disciplines, but perhaps the most interesting property of these nanomaterials can be seen in their immense thermal response under the influence of alternating magnetic fields. Currently popularized as an alternative cancer treatment through localized hyperthermia, iron oxide nanoparticle induction heating presents an interesting physical phenomenon that distinguishes itself from macroscopic induction heating. Understanding how a single spherical particle behaves is relatively simple and remains well documented; however, magnetic interactions of a single particle often extend over many length scales, affecting numerous neighboring particles in the …

Auto-Calibration Of Wim Using Traffic Stream Characteristics, Johnson Baker

Graduate Theses and Dissertations

This project evaluates the performance of Weigh-in-Motion (WIM) auto-calibration methods used by the Arkansas Department of Transportation (ARDOT). Typical auto-calibration algorithms compare the WIM measured weights of vehicles from the traffic stream to reference values, using five-axle tractor-trailer configured trucks for comparisons, e.g. Federal Highway Administration (FHWA) Class 9. Parameters of the existing algorithms including the Front Axle Weight (FAW) reference value, the sampling frequency required to update the calibration factor, and thresholds for Gross Vehicle Weight (GVW) bins were evaluated. The primary metric used to estimate algorithm performance was Mean Absolute Percent Error (MAPE) between the WIM and static …

Motor Control Systems Analysis, Design, And Optimization Strategies For A Lightweight Excavation Robot, Austin Jerold Crawford

Graduate Theses and Dissertations

This thesis entails motor control system analysis, design, and optimization for the University of Arkansas NASA Robotic Mining Competition robot. The open-loop system is to be modeled and simulated in order to achieve a desired rapid, yet smooth response to a change in input. The initial goal of this work is to find a repeatable, generalized step-by-step process that can be used to tune the gains of a PID controller for multiple different operating points. Then, sensors are to be modeled onto the robot within a feedback loop to develop an error signal and to make the control system self-corrective …

Manufacturing And Testing The Permanent Magnet Linear Motor, Renjie Kang

Senior Theses

Controlled mechanical motion is vital in many useful applications in technology. Among them, linear motors have advantages over traditional rotating motors. In this work, we built a permanent magnet linear motor to test and measure its energy efficiency. A maximum 29% total energy efficiency, and 67% energy transfer rate, were detected. In addition, a C-shape support structure was added to the moving part in order to increase the moving accuracy. The tests show that, with the support structure, the fluctuation in the vertical direction decreases significantly, but the friction of the system slightly increases.

Investigation Of The Surface Topology Changes Associated With Fatigue, Randall D. Kelton

Material Science and Engineering Dissertations - Archive

Metals have long been known to change their surface topology when subjected to a plastic strain. Given that a plastic zone exists at the tip of a propagating crack, it would seem natural to quantitatively study surface topology changes associated with nucleating and propagating fatigue cracks. So far the workers in this study have only found one measurement of the surface topology changes associated with a nucleating crack. The current research seeks to study and refine, a possible correlation between crack growth and surface topology changes, with the object to develop a damage index for fatigue cracking from surface topology …

Electrochemical Energy Storage Integration Challenges Within High Voltage Distributed Generation Power System Architectures, Charles N. Nybeck

Electrical Engineering Dissertations - Archive

Future stationary and mobile microgrids may be deployed with a number of high power electrical loads that operate transiently. The transient nature of the loads will impart high stress on a microgrid’s power system, possibly pushing it outside of the acceptable power quality standards. To restore power quality and increase system reliability, it is being proposed that electrochemical energy storage systems be used as a buffer. Energy storage systems that store a great deal of energy and could be used with open circuit potentials (OCPs) as high as 1 kV. Since size and weight on a mobile microgrid is limited, …

Wearable Biomedical Sensors, Wenyuan Shi

Electrical Engineering Dissertations - Archive

Focusing on current major research interests about the wearable biomedical sensors, numerous achievements contributed by researchers and engineers are reviewed in chapter 1. Development and research trends, as well as challenges of the wearable technologies are discussed. In chapter 2, a new double-resonance sensor was presented for monitoring body dehydration with two resonant frequencies. Using the waveguide method and the finite-element simulations, the sensor was designed with optimal parameters. Electromagnetic field distributions, Q factors, and sensitivities of the sensor are analyzed. The sensor’s equivalent circuit was deduced. The finite-element model and the equivalent circuit model were simulated for identifying various …

Real-Time Multi-Pulse Rectifier Models For Power Hardware-In-The-Loop Implementation In Medium Voltage Dc Microgrid Applications, Brian J. Mcree

Electrical Engineering Dissertations - Archive

Microgrids have proliferated the landscape of the world’s power systems as distributed energy generation, energy storage, and evolving electrical loads become more abundant. Microgrids offer many advantages to the end user of electrical power over traditional power distribution networks that rely on exceedingly large rotating machines producing power for a large group of electrical loads over long physical distances. Microgrids provide a unique benefit to smaller electrical networks that may be isolated, may have unique electrical loads, or may have a network of energy storage devices that can be utilized to serve the microgrid in particular operational scenarios. With the …

Production Of Liquid Fuels From Natural Gas: Simulation Of Synthesis Gas And Fischer-Tropsch Reactors, Saiedeh Arabi Bolaghi

Mechanical and Aerospace Engineering Dissertations - Archive

Gas to Liquid (GTL) processes chemically convert natural gas to valuable liquid hydrocarbon products. The GTL process considered in this research is comprised of three phases: 1) syngas production, 2) Fischer-Tropsch synthesis (FTS), and 3) product separation. This study focuses on the simulation and optimization of a GTL process to convert natural gas to more valuable liquid fuels. In syngas production, steam methane reforming (SMR) is typically used although it requires an external heat source due to the endothermic nature of the reaction. In addition, the SMR approach produces syngas with a hydrogen to carbon monoxide ratio that is not …

Gasdynamic Phenomena And Propulsive Performance Of Pulse Detonation Engines, James T. Pearce

Mechanical and Aerospace Engineering Dissertations - Archive

The pulsed detonation engine (PDE) is an advanced propulsion system that makes use of intermittent detonations to provide thrust. In recent decades, the PDE has been at the center of various propulsion research efforts focused on practical implementation of a reliable detonation-based engine for aerospace propulsion applications. However, many design challenges remain to be solved due to the PDEs unsteady operating characteristics. In particular, the unsteady nature of the thrust chamber flow field inherent to the PDE operation makes the design of nozzles aimed at adequately expanding the burned detonation products especially difficult. In order to address this design challenge, …

Onboard Payload Mass Estimation And Electric Propulsion Modeling For Multicopters With Application In Unmanned Aerial Systems, Abel Martinez Martinez Martinez

Mechanical and Aerospace Engineering Theses - Archive

Unmanned vehicles are the future. The aim of the future online retailers, delivery and transportation companies would be air delivery using unmanned aerial vehicles. Multicopters are becoming rapidly famous because they o er a relatively easy-to-fly platform that is also very stable, and their mechanical simplicity. The possibility of estimating the weight of the multicopter in real time is really useful. A weight estimation system that could be implemented in multicopters with cable suspended payloads without using any extra sensors is presented in this thesis. The weight estimation system uses a functional relationship that correlates Pulse Position Modulation (PPM) signal …

Experimental Analysis For Optimization Of Thermal Performance Of A Server In Single Phase Immersion Cooling, Pravin Ashok Shinde

Mechanical and Aerospace Engineering Theses - Archive

Liquid immersion cooling of servers in synthetic dielectric fluids is an emerging technology which offers significant cooling energy saving and increased power densities for data centers. A noteworthy advantage of using immersion cooling is high heat dissipation capacity which is roughly 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include high rack density, better server performance, even temperature profile, reduction in noise. The enhanced thermal properties of oil lead to the considerable saving of both upfront and operating cost over traditional methods. In this study, a server is completely submerged in a synthetic dielectric fluid. Experiments …

Onboard Payload Mass Estimation And Electric Propulsion Modeling For Multicopters With Application In Unmanned Aerial Systems, Abel Martinez Martinez

Mechanical and Aerospace Engineering Theses - Archive

Unmanned vehicles are the future. The aim of the future online retailers, delivery and transportation companies would be air delivery using unmanned aerial vehicles. Multicopters are becoming rapidly famous because they o er a relatively easy-to-fly platform that is also very stable, and their mechanical simplicity. The possibility of estimating the weight of the multicopter in real time is really useful. A weight estimation system that could be implemented in multicopters with cable suspended payloads without using any extra sensors is presented in this thesis. The weight estimation system uses a functional relationship that correlates Pulse Position Modulation (PPM) signal …

Computational Analysis For Thermal Optimization Of Server For Single - Phase Immersion Cooling, Dhruvkumar Vimalkumar Gandhi

Mechanical and Aerospace Engineering Theses - Archive

Complete immersion of servers in synthetic dielectric fluids is rapidly becoming a popular technique to minimize the energy consumed by data centers for cooling purposes. In general, immersion cooling offers noteworthy advantages over conventional air-cooling methods as synthetic dielectric fluids have high heat dissipation capacities which are roughly about 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include even temperature profile on chips, reduction in noise and addressing reliability and operational enhancements like whisker formation and electro-chemical migration. Nevertheless, lack of data published and availability of long-term reliability data on immersion cooling is insufficient which makes …

Electroextraction Across Droplet-Droplet Interface, Subhadeep Chakraborti

Mechanical and Aerospace Engineering Theses - Archive

Extraction of analytes from solvents is a crucial part of many medical, clinical, industrial and refinery processes. It is required for preconcentration of analytes into other solvents, purification of solvents and detection of harmful or toxic molecules. One of the very important methods of extraction in microfluidics is liquid-liquid extraction (LLE). LLE involves the use of two immiscible liquids for diffusion of analytes across the interface. Recently there has been a growing interest in the coupling of external electric field with LLE to enhance the extraction of charged analytes. This has led to the birth of a new extraction method …

Role Of Angiotensin I And Ii On The Tissue Mechanics Of The Aortic Heart Valve Via Receptor Binding And Converting Enzymes, Josh Fahy

Biomedical Engineering Undergraduate Honors Theses

The renin-angiotensin system (RAS) plays a crucial role in the regulation of renal, cardiac, and vascular physiology. This system regulates in vivo blood pressure and fluid balance. As renal blood flow decreases, the kidneys convert prorenin into renin and secrete it into the circulatory system. Renin then converts angiotensinogen into angiotensin I (ang-I). The ang-I is then converted into angiotensin II (ang-II) by the angiotensin-converting enzyme (ACE). Ang-II, a vasoconstrictor, increases blood pressure by causing the blood vessels to narrow. Recent evidence suggests that RAS may be involved in the progression of valve disease, most notably, aortic stenosis.

The first …

Investigation Of Acute Radiation-Induced Changes In Oxygenation In A Murine Breast Tumor Model, Alaa Abdelgawad

Biomedical Engineering Undergraduate Honors Theses

Around 50-60% of all cancer patients undergo radiation therapy. Although some patients show complete response with no recurrence, a significant proportion of the population still develop radiation resistance. It is important to identify tumor resistance at early stages of therapy in order to adjust treatment protocol and avoid extra exposure to radiation. Current methods to assess treatment response are only limited to anatomical measurements of tumor volume after therapy. Novel approaches that shed the light on any functional information during the course of radiotherapy could significantly improve our ability to identify patients who do not respond to radiation therapy. Diffuse …

Effect Of Dielectric Inter-Layer In Performance Of The Multi-Functional Material In Mechanical, Thermal And Environmental Loading Conditions, Rauhon Ahmed Shaik

Mechanical and Aerospace Engineering Theses - Archive

The demand for Electrical power storage devices for space shuttle, aircraft, car, bus and marine vehicles increased a great deal to have a greener and safer world. Decades of research has been done on development of light weight and high-performance energy storage devices such as batteries and structural capacitors. The use of structural capacitors can solve the high-performance energy storage requirement with no dead weight and also gives a strong structure. However, these heterogeneous materials experience different thermal expansions across the dielectric and electrodes inter layers due to which the energy storage capacity and mechanical performance evolve over time. Hence, …

Methodology To Develop Artificial Neural Network Based Control Strategies For Multiple Air-Cooling Units In A Raised Floor Data Center, Vibin Shalom Simon

Mechanical and Aerospace Engineering Theses - Archive

A data center consists of a hierarchy of systems with dedicated control algorithms dictating their operational states. We could say, there exists an ensemble of dynamical systems, each executing a control task, while the global objective is to drive the overall system to an optimum i.e. minimum total operational power at desired rack inlet temperatures. The dynamics of the Information Technology Equipment (ITE) workload and the cooling provisioning is non-linear in spatial and temporal parameter space. Data-driven modelling is one method to realistically model such non-linear dynamics and make predictions that are necessary for improved control design of the cooling …

Ultra-Small Gold Nanoparticles By Galvanic Replacement Of Larger Silver Nanoparticles, Chang Ting Lin

Material Science and Engineering Theses - Archive

In the last two decades, Au nanoparticles have been extensively explored for their biomedical applications, which is mainly driven by their biocompatibility and special optical properties known as surface plasmon resonance (SPR) effect. A variety of Au nanoparticles with different sizes and shapes have been synthesized and tested both in vitro and in vivo. For in vivo applications, it is usually required that Au nanoparticles can be cleared through urine (renal clearance). Renal clearance is determined by several factors of Au nanoparticles, including size, shape and surface modification. In this thesis, for the purpose of using Au nanoparticles as carriers …

Element-Specific Nanoparticle Placement Toward Fabricating Multi-Element Metastructures, Lei Wu

Material Science and Engineering Theses - Archive

Nanoscale entities such as semiconductor nanoparticles, magnetic nanoparticles, metal nanoparticles, and dielectric nanoparticles have attracted a lot of attention due to their novel electrical, optical, and magnetic properties that their bulk materials cannot produce. These unique properties promise applications in nano-optical devices, ultra-sensitive sensors, single electron transistors, and high-density data storages. Moreover, to these captivating properties of the individual nanoparticles, it has been found that novel and scientifically important properties can be obtained when nanoparticles are arranged in specific configurations. Examples include nanoparticle dimers, hexamers, heptamers, and nanoparticle arrays. Until now, however, most studies have focused on one-element nanoparticle systems. …

Enhancing Anaerobic Oxidation Of Methane In Landfill Cover Soil, Niloofar Parsaeifard

Civil Engineering Dissertations - Archive

Methane (CH4) is one of the major greenhouse gases (GHG) generated in landfills and has a global warming effect 28 times more than carbon dioxide (CO2). Therefore, decreasing methane emissions into the atmosphere from landfills is critically important. In the upper portions of a landfill cover, methane is exposed to oxygen and oxidized aerobically to carbon dioxide while passing through the cover soil; this lowers the overall contribution of the landfill to climate change. However, because of the low permeability of the landfill cover, no aerobic oxidation occurs in the bottom of the cover because oxygen cannot penetrate to those …

Mathematical Modeling Of Blood Pressure And Cerebral Blood Flow Using Photoplethysmography Signal, Armin Soltan Zadi

Bioengineering Dissertations - Archive

Continuous and non-invasive monitoring of blood pressure (BP) and cerebral blood flow (CBF) has numerous clinical and health maintenance applications. Of particular interest is monitoring of BP and CBF during events that stress the cardiovascular system such as cessation of breathing during sleep apnea. Current means and methods of continuous measurement of these signals are either invasive or require expensive equipment. Therefore, investigation of new methods of continuous estimation of the BP and CBF are of high interest. One attractive alternative is to use photoplethysmography (PPG) technique to estimate BP and CBF, as PPG is shown to be able to …

The Hip-Spine Effect: How Pathological Femoro-Pelvic Interactions Contribute To Abnormal Lumbar Spine Loading, Anthony Nicholas Khoury

Bioengineering Dissertations - Archive

ABSTRACT THE HIP-SPINE EFFECT: HOW PATHOLOGICAL FEMORO-PELVIC INTERACTIONS CONTRIBUTE TO ABNORMAL LUMBAR SPINE LOADING Anthony Nicholas Khoury, Ph.D. The University of Texas at Arlington, 2019 Supervising Professor: Hal David Martin Cheng-Jen Chuong Lumbar pathology has been shown to explain hip pain, as hip pathology is involved in the development of lumbar pain by the disruption of normal lumbopelvic kinematics. Hip pathologies that contribute to lumbar pain include flexion deformities, osteoarthritis, congenital hip dislocation, and limited hip range of motion. To date there is a paucity of research that actively looks to investigate the symbiotic relationship between the hip and the …

Performance Of Concrete Slabs With Embedded Hydronic Loops For Geothermally Based Bridge De-Icing Applications, Mark Hurley

Civil Engineering Theses - Archive

Geothermal energy has always been available as a renewable thermal reserve, however, only recently has it been unlocked as a potential source of energy to de-ice bridges and roadways. The ability to efficiently extract the geothermal reserves has been accomplished with the advent of new technology. Each progressing year, the refinement of technology has led to a reduction in the input required to achieve a desired output. For the case of bridge de-icing, the extracted input of thermal energy must exceed the required demands to permit de-icing. The conventional approach to de-icing (using chemicals, salt, and sand) works as a …

Service Life Prediction And Risk Analysis Of Reinforced Concrete Gravity Flow Pipes Using Reliability Theory, Khaled Saleh Abuhishmeh

Civil Engineering Theses - Archive

Reinforced concrete pipes are susceptible to different types of deteriorations that threaten their structural capacity and serviceability. Failure of these structures or losing parts of their operational capabilities may cause undesirable consequences that affect the surrounding environment, public health and the economy. The main objectives of this research are to estimate the service life, and to evaluate the level of risk of reinforced concrete sewer pipes (RCP) that are under persistent chemical deterioration caused by the sulfide attack that leads to excessive erosion along the pipe’s interior wall. In order to estimate the service life, reliability theory is used by …

Flexural Behavior Of Preflex Sfrc-Encased Steel Joist Composite Beams, Nancy Thazhampallatu Varughese

Civil Engineering Theses - Archive

This research investigates the behavior of encased steel composite beams within steel fiber reinforced concrete (SFRC) in straight and preflex beams, using nonlinear analysis. ABAQUS FEA software has been adopted. Composite steel beams encased in fiber reinforced concrete are analyzed and a comparison is made with available experimental results. Good agreement with the experimental results is observed. Upwards camber of the steel section is introduced on the steel joist. It’s found that the preflex section can increase the ultimate load capacity by 10% and decrease midspan displacement by 13% of the same beams without the preflex steel section. Steel fiber …

Experimental Investigation Of Concrete Breakout Strength Of Anchors In Shear Within Fiber Reinforced Concrete, Mohammad Akram Khanfar

Civil Engineering Theses - Archive

This study investigates the effects of Polypropylene fibers on the concrete breakout strength of cast in place anchors in shear under different loading rates. The steel headed anchors were cast within concrete specimens of different amounts of Polypropylene fibers. Four differing mixtures were produced using, 0, 0.5, 1, and 1.5% fibers by volume of the mixture. Their physical properties were calculated through testing at the Civil Engineering Laboratory Building. In total, 16 cylindrical specimens, 4” in diameter and 8” in height, and 6 beam specimens, 6”x6”x20” were produced and tested. After 28 days of curing, the specimens were tested for …

Effect Of Termite Gut Microorganism Tav5 Ratios On Lignin Degradation And Methane Generation From Paper, Yard, And Wood Waste, Hoda Rahimi

Civil Engineering Dissertations - Archive

Methane from anaerobic processes is being increasingly utilized as an alternative energy source in developed countries, via large projects that extract methane from landfills or wastewater treatment plants. Anaerobic degradation of organic material (biomass) involves decomposition by bacteria under humid conditions without any oxygen. Organic carbon deposited in landfills is converted by microbes to carbon dioxide (CO2) and methane (CH4). If the methane is not captured, it contributes to climate change (28 times more effectively than CO2 on a per-mass basis). If the methane is captured, it can be used as a renewable energy resource. Lignocellulose comprises a significant portion …

Investigation Of Gas- And Liquid-Phase Sewer Environmental Factors Leading To Microbially-Induced Concrete Corrosion, Aiswarya Acharath Mohanakrishnan

Civil Engineering Theses - Archive

Sewer systems are a principal element of infrastructure in modern cities, accounting for massive amounts of public investments made over many decades and can be considered as an asset of the nation. Many concrete manholes in the sewer system are deteriorating due to the attack of sulfuric acid produced by microorganisms in a process termed as Microbial Induced Concrete Corrosion (MICC). The life span of concrete sewer elements significantly reduces from 100 years to 30–50 years, in extreme cases even down to 10 years. The primary aim of this study is to enhance the understanding of the correlation between gas-phase …