Physical Sciences and Mathematics Commons^™

Development Of High-Speed Photoacoustic Imaging Technology And Its Applications In Biomedical Research, Yun He

McKelvey School of Engineering Theses & Dissertations

Photoacoustic (PA) tomography (PAT) is a novel imaging modality that combines the fine lateral resolution from optical imaging and the deep penetration from ultrasonic imaging, and provides rich optical-absorption–based images. PAT has been widely used in extracting structural and functional information from both ex vivo tissue samples to in vivo animals and humans with different length scales by imaging various endogenous and exogenous contrasts at the ultraviolet to infrared spectrum. For example, hemoglobin in red blood cells is of particular interest in PAT since it is one of the dominant absorbers in tissue at the visible wavelength.The main focus of …

Numerical And Semi-Analytical Estimation Of Convective Heat Transfer Coefficient For Buildings In An Urban-Like Setting, Anwar Demsis Awol

Electronic Thesis and Dissertation Repository

Urban building arrangements such as packing density, orientation and size are known to influence the microclimate surrounding each building. Studies on the impact of urban microclimatic changes on convective heat transfer coefficient (CHTC) from a stock of buildings, however, have been rare in surveyed literature. The present study focuses on numerical and analytical investigation of CHTC from building-like models with homogeneous set of equal and unequal planar and frontal densities. Consequently, the study discusses the CHTC response in relation to broader changes in the urban surface form. Part of the process involves the development of a simplified one-dimensional semi-analytical CHTC …

Characterization And Computational Modelling For The Garnet Oxide Solid State Electrolyte Ta-Llzo, Colin A. Versnick

Electronic Thesis and Dissertation Repository

The all-solid-state-battery (ASSB) serves as a promising candidate for next generation lithium ion batteries for significant improvements in battery safety, capacity, and longevity. Of the material candidates researched to replace the conventionally used liquid electrolyte, the garnet oxide Ta-LLZO (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) has received much attention thanks to its high chemical and electrochemical stability, and ionic conductivity which rivals that of liquid electrolytes. While much investigation has taken place regarding the electrochemical performance of Ta-LLZO, much less is known about the micromechanics, including microstructural characterization, stress and strain development, and material failure …

A Rotating Aperture Mask For Small Telescopes, Edward L. Foley

Master's Theses

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that …

Residual Stress Models For Large Eddy Simulation Of Stratified Turbulent Flows, Felipe Augusto Ventura De Bragança Alves

Doctoral Dissertations

The residual stresses and scalar fluxes are required to close the momentum and scalar transport equations in simulations of turbulence that are not fully resolved in space. In stratified turbulence, the stress and fluxes are statistically anisotropic unless the smallest resolved length scale is smaller than the Ozmidov scale and the buoyancy Reynolds number is sufficiently high for there to exist a range of scales that is statistically isotropic. In this work, a tensorial basis set is derived analytically that potentially contains sufficient information about the anisotropic interaction between resolved and residual scales. The residual stress tensor is evaluated by …

Polymeric Impulsive Actuation Mechanisms: Development, Characterization, And Modeling, Yongjin Kim

Doctoral Dissertations

Recent advances in the field of biomedical and life-sciences are increasingly demanding more life-like actuation with higher degrees of freedom in motion at small scales. Many researchers have developed various solutions to satisfy these emerging requirements. In many cases, new solutions are made possible with the development of novel polymeric actuators. Advances in polymeric actuation not only addressed problems concerning low degree of freedom in motion, large system size, and bio-incompatibility associated with conventional actuators, but also led to the discovery of novel applications, which were previously unattainable with conventional engineered systems. This dissertation focuses on developing novel actuation mechanisms …

Modeling Of Buildings With Electrochromic Windows And Thermochromic Roofs, Hua-Ting Kao

USF Tampa Graduate Theses and Dissertations

Air conditioning and heating have increased substantially during the past two decades. According to a survey, buildings consume about 73% of the total electricity in the United States, accounting for 41% of all other energy in the world. At the same time, building skin technologies are constantly improving. Electrochromic and thermochromic are two exciting new technologies that can help reduce the energy consumption of a building. The purpose of this work is to increase our understanding of how much the use of electrochromic (EC) and thermochromic (TC) technologies can reduce the energy consumption of residential and commercial buildings in two …

A Cfd Study Of Steady Fully Developed Laminar Flow Through A 90-Degree Bend Pipe With A Square Cross-Sectional Area, Subodh Sushant Toraskar

Mechanical & Aerospace Engineering Theses & Dissertations

Fluid flow through a closed curved conduit has always been a topic of extensive research, as it has many practical and industrial applications. The flow is generally characterized by a presence of secondary flow, vortical motions and pressure losses for different flow regimes. These observed irregularities may positively or negatively impact the flow. They are beneficial for cases where mixing of fluids is required, usually observed for multiphase flow regimes or detrimental for cases involving particles in the fluid. There are also instances where a particle-laden fluid transported through the curved pipe was directly related to corrosion- erosion related problems. …

General Nonlinear-Material Elasticity In Classical One-Dimensional Solid Mechanics, Ronald Joseph Giardina Jr

University of New Orleans Theses and Dissertations

We will create a class of generalized ellipses and explore their ability to define a distance on a space and generate continuous, periodic functions. Connections between these continuous, periodic functions and the generalizations of trigonometric functions known in the literature shall be established along with connections between these generalized ellipses and some spectrahedral projections onto the plane, more specifically the well-known multifocal ellipses. The superellipse, or Lam\'{e} curve, will be a special case of the generalized ellipse. Applications of these generalized ellipses shall be explored with regards to some one-dimensional systems of classical mechanics. We will adopt the Ramberg-Osgood relation …

Microextrusion 3d Printing Of Optical Waveguides And Microheaters, Edidiong Nseowo Udofia

Graduate Theses and Dissertations

The drive for smaller and more compact devices presents several challenges in materials and fabrication strategies. Although photolithography is a well-developed method for creating microdevices, the disparate requirements in fabrication strategies, material choices, equipment and process complexities have limited its applications. Microextrusion printing (μEP) provides a promising alternative for microfabrication. Compared to the traditional techniques, the attractions lie in the wide range of printable material choice, greater design freedom, fewer processing steps, lower cost for customized production, and the plurality of compatible substrates. However, while extrusion-based 3D printing processes have been successfully applied at the macroscale, this seeming simplicity belies …

Optimizing Self-Healing Wind Turbine Blades Utilizing Dicyclopentadiene Infused Vascular Networks, Giovanni Lewinski

Theses and Dissertations

Self-healing wind turbine blades can reduce costs associated with maintenance, repair, and energy compensation. Self-healing is the ability to sustain and recover from damage autonomously. The self-healing presented in this paper uses the reaction of two agents Dicyclopentadiene, DCPD, and Grubbs’ first-generation catalyst, henceforward known as a catalyst to fuel this recovery. DCPD is housed as a liquid isolated from the catalyst until a damaging event occurs, causing the two agents to mix and solidify to form the thermoset Polydicyclopentadiene, PDCPD. We discuss the efforts made to optimize the self-healing properties of wind turbine blades and provide new systems to …

Development Of A Ground-Based Aerial-Tracking Instrument For Open-Path Spectroscopy To Monitor Atmospheric Constituents, Haden Hodges

Civil Engineering Undergraduate Honors Theses

A ground-based aerial-tracking instrument, known as the Ground Tracker, designed to provide spectral data to quantify greenhouse gases is under development. The Ground Tracker includes an Optical System including a high power rifle scope, video camera, and spectrometer used to locate an active light source from the Emitter, and collect spectral data by utilizing an actuating mirror. The implementation of this instrument could be made low cost by utilizing existing weather balloon infrastructure to allow the Emitter to be placed into the lower stratosphere. The recovery of the emitter will be possible by tracking the GPS coordinates. Weather balloon instrument …

Characterization Of Single- And Multi-Phase Shock-Accelerated Flows, Patrick John Wayne

Mechanical Engineering ETDs

Experiments conducted in the Shock Tube Facility at the University of New Mexico are focused on characterization of shock-accelerated flows. Single-phase (gaseous) initial conditions consist of a heavy gas column of sulfur hexafluoride seeded with approximately 11% acetone gas by mass. Visualization of the image plane for gaseous initial conditions is accomplished via planar laser-induced fluorescence (PLIF) with a high-powered Nd:YAG ultraviolet laser and an Apogee Alta U-42 monochrome CCD camera, with a quantum efficiency > 90%. Multi-phase (gas-solid) initial conditions consist of glass micro-beads deposited on small 1-cm diameter discs of specific surface chemistry, mounted flush with the bottom wall …

Flow-Induced Oscillations In Floating Offshore Wind Turbines, Daniel Carlson

Doctoral Dissertations

The goal of this thesis is to experimentally study the structural dynamics, wake interaction, and fluid forces on the multiple-degree of freedom systems typical of floating wind turbines. Vortex--surface alignment about flexibly-mounted prisms is studied to investigate the response of barges and semi-submersible hulls, and new results pertaining to the galloping response kink for a prism with dual inline--crossflow resonance is presented. Flow--induced oscillations of a spar model free to rotate in 3D space is replicated and observed as 2D figure--eight orbits about the center of the spar. Methods to suppress the flow from exciting the spar are proposed. The …

Design Of Variable Wall Thickness Geometry And Performance Mapping Of Scroll Expanders For Distributed Power Generation, Arun Kumar Narasimhan

USF Tampa Graduate Theses and Dissertations

Low-temperature heat sources such as industrial waste heat, solar, and geothermal are more suitable for small-scale power generation rather than utility scale. In order to maximize the electricity generated from low-temperature heat sources, an efficient expansion device for small-scale power output is necessary. This research work has focused on evaluating the use of a scroll expander and improving its geometrical design for the power output range of 1-25 kW_e.

The first part of the work focusses on modeling the performance of a scroll expander using two non-dimensionless parameters, namely, specific speed and specific diameter. Performance of a scroll …

Investigation Of Fundamental Principles Of Rigid Body Impact Mechanics, Khalid Alluhydan

Mechanical Engineering Research Theses and Dissertations

In impact mechanics, the collision between two or more bodies is a common, yet a very challenging problem. Producing analytical solutions that can predict the post-collision motion of the colliding bodies require consistent modeling of the dynamics of the colliding bodies. This dissertation presents a new method for solving the two and multibody impact problems that can be used to predict the post-collision motion of the colliding bodies. Also, we solve the rigid body collision problem of planar kinematic chains with multiple contacts with external surfaces.

In the first part of this dissertation, we study planar collisions of Balls and …

Maximizing And Modeling Malonyl-Coa Production In Escherichia Coli, Tatiana Thompson Silveira Mello

LSU Master's Theses

In E. coli, fatty acid synthesis is catalyzed by the enzyme acetyl-CoA carboxylase (ACC), which converts acetyl-CoA into malonyl-CoA. Malonyl-CoA is a major building block for numerous of bioproducts. Multiple parameters regulate the homeostatic cellular concentration of malonyl-CoA, keeping it at a very low level. Understanding how these parameters affect the bacterial production of malonyl-CoA is fundamental to maximizing it and its bioproducts. To this end, competing pathways consuming malonyl-CoA can be eliminated, and optimal nutritional and environmental conditions can be provided to the fermentation broth. Most previous studies utilized genetic modifications, expensive consumables, and high-cost quantification methods, making …

Nano Fab Lab 63, Brian K. Deemer, Josh Clemons, Nick Brodine, Delaney Fitzsimmons

Mechanical Engineering

Lawrence Livermore National Laboratories (LLNL) has several steps in the production process for ceramic nanofiber tubes that they would like to improve - electrospinning, cutting, rolling, sealing and heat treating. We undertook the challenge to deliver LLNL with a semi-automated process that efficiently integrates the steps of cutting, rolling, and sealing to save time and improve control over end dimensions. In this document, we discuss the technical background of the manufacturing steps currently followed to create nanofiber tubes, identify which steps are incorporated in our prototype and explain how they will interface with one another, define the design requirements, present …

Predicting The Mechanical Properties Of Nanocomposites Reinforced With 1-D, 2-D And 3-D Nanomaterials, Scott Edward Muller

Graduate Theses and Dissertations

Materials with features at the nanoscale can provide unique mechanical properties and increased functionality when included as part of a nanocomposite. This dissertation utilizes computational methods at multiple scales, including molecular dynamics (MD) and density functional theory (DFT), and the coupled atomistic and discrete dislocation multiscale method (CADD), to predict the mechanical properties of nanocomposites possessing nanomaterials that are either 1-D (carbyne chains), 2-D (graphene sheets), or 3-D (Al/amorphous-Si core-shell nanorod).

The MD method is used to model Ni-graphene nanocomposites. The strength of a Ni-graphene nanocomposite is found to improve by increasing the gap between the graphene sheet and a …

Fault Adaptive Workload Allocation For Complex Manufacturing Systems, Charlie B. Destefano

Graduate Theses and Dissertations

This research proposes novel fault adaptive workload allocation (FAWA) strategies for the health management of complex manufacturing systems. The primary goal of these strategies is to minimize maintenance costs and maximize production by strategically controlling when and where failures occur through condition-based workload allocation.

For complex systems that are capable of performing tasks a variety of different ways, such as an industrial robot arm that can move between locations using different joint angle configurations and path trajectories, each option, i.e. mission plan, will result in different degradation rates and life-expectancies. Consequently, this can make it difficult to predict when a …

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 …

Exploring The Electrical Properties Of Twisted Bilayer Graphene, William Shannon

Senior Theses

Two-dimensional materials exhibit properties unlike anything else seen in conventional substances. Electrons in these materials are confined to move only in the plane. In order to explore the effects of these materials, we have built apparatus and refined procedures with which to create two-dimensional structures. Two-dimensional devices have been made using exfoliated graphene and placed on gold contacts. Their topography has been observed using Atomic Force Microscopy (AFM) confirming samples with monolayer, bilayer, and twisted bilayer structure. Relative work functions of each have been measured using Kelvin Probe Force Microscopy (KPFM) showing that twisted bilayer graphene has a surface potential …

Transferring Power Through A Magnetic Couple, Nickolas Cruz Villalobos Jr.

Senior Theses

Properties of several working magnetic coupled rotors have been measured and their performance compared to theoretical models. Axial magnetic couplers allow rotors to work within harsh environments, without the need for seals, proper alignment, or overload protection on a motor. The influence of geometrical parameters, such as distance from the center of the rotors, polarity arrangement, and the number of dipole pairs were experimentally tested. These results can be used to improve rotor designs, to increase strength and efficiency.

The Design And Optimization Of Jet-In-Cross-Flow (Jicf) For Engineering Applications: Thermal Uniformity In Gas-Turbines And Cavitation Treatment In Hydro-Turbines, Tarek Mahmoud Mohammed Elgammal

Theses and Dissertations

Jet-in-cross-flow (JICF) is a well-known term in thermal flows field. Ranging from the normal phenomenon like the volcano ash and dust plumes to the designed film cooling and air fuel mixing for combustion, JICF is always studied to understand its nature at different conditions. Realizing the behavior of interacting flows and importance of many variables lead to the process of reiterating the shapes and running conditions for better outcomes or minimizing the losses. Summarizing the process under the name of optimization, two JICF applications are analyzed based on the principles of thermodynamics and fluid mechanics, then some redesigns are proposed …

Methods To Remotely Eliminate Biofilm From Medical Implants Using 2.4 Ghz Microwaves, Brett Glenn

Mechanical Engineering Undergraduate Honors Theses

Infections associated with biofilm growth are usually challenging to eradicate due to their high tolerance toward antibiotics [11, 12]. Biofilms often form on the inert surfaces of medically implanted devices [13]. No matter the sophistication, microbial infections can develop on all medical devices and tissue engineering constructs [12]. Related infections lead to 2 million cases annually in the U.S., costing the healthcare system over $5 billion in additional healthcare expenses [12].

Novel solutions to biofilm’s microbial colonization span the spectrum of engineering and science disciplines. Yet a practical solution still does not exist. The research presented here will explore a …

Construction Of A Hyperspectral Camera Using Off-The-Shelf Parts And 3d-Printed Parts, Connor Heo

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences (ACSPS) is working together with the Mechanical Engineering Department to build a modifiable camera with 3D-printed parts and off-the-shelf parts (sourced from Edmund Optics and Amazon). The design is to be readily changeable, primarily with the 3D printed parts, as to accommodate new ideas and functionalities in the future. Ultimately, the camera should be relatively cheap while maintaining functionality for proposed use cases. Earlier versions of the design will be tested extensively and rapidly updated in the ACSPS labs with benchtop testing. This will involve subjects with both visible and infrared emissions, …

Lithium Molybdate-Sulfur Battery., Ruchira Ravinath Dharmasena

Electronic Theses and Dissertations

Rechargeable energy storage systems play a vital role in today’s automobile industry with the emergence of electric vehicles (EVs). In order to meet the targets set by the department of energy (DOE), there is an immediate need of new battery chemistries with higher energy density than the current Li- ion technology. Lithium–sulfur (Li–S) batteries have attracted enormous attention in the energy-storage, due to their high specific energy density of 2600 Wh kg^-1 and operational voltage of 2.0 V. Despite the promising electrochemical characteristics, Li-S batteries suffer from serious technical challenges such as dissolution of polysulfides Li₂S_{x …}

A Monolithic Arbitrary Lagrangian-Eulerian Finite Element Method For An Unsteady Stokes/Parabolic Interface Problem, Ian Kesler

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, a non-conservative arbitrary Lagrangian-Eulerian (ALE) method is developed

and analyzed for a type of linearized Fluid-Structure Interaction (FSI) problem in a

time dependent domain with a moving interface - an unsteady Stokes/parabolic interface

problem with jump coefficients. The corresponding mixed finite element approximation is

analyzed for both semi- and full discretization based upon the so-called non-conservative

ALE scheme. The stability and optimal convergence properties in the energy norm are

obtained for both schemes.

The Affective Perceptual Model: Enhancing Communication Quality For Persons With Pimd, Jadin Tredup

UNLV Theses, Dissertations, Professional Papers, and Capstones

Methods for prolonged compassionate care for persons with Profound Intellectual and Multiple Disabilities (PIMD) require a rotating cast of import people in the subjects life in order to facilitate interaction with the external environment. As subjects continue to age, dependency on these people increases with complexity of communications while the quality of communication decreases. It is theorized that a machine learning (ML) system could replicate the attuning process and replace these people to promote independence. This thesis extends this idea to develop a conceptual and formal model and system prototype.

The main contributions of this thesis are: (1) proposal of …

Fracture Toughness And Fatigue Crack Growth Rate Characterization Of Inconel 718 Formed By Laser Powder Bed Fusion, Charles C. Hohnbaum

Theses and Dissertations

Continuing improvement in the field of AM of metals provides the opportunity for direct fabrication of aerospace parts. AM was once used in large part for rapid prototyping but improvements in technology and increases in the knowledge base of AM materials has provided the opportunity for manufacture of AM parts for operational use. The ability to create low numbers of unique parts without having to invest in expensive tooling provides great economic incentive to utilize this technique. IN718 is the most common high temperature alloy used in the aerospace industry and lends itself readily to formation by LPBF. The superior …