Materials Science and Engineering Commons^™

Inverse Problems Using Reduced Basis Method, Phil Gralla

All Theses

Inverse Problems is a field of great interest for many applications, such as parameter identification and image reconstruction. The underlying models of inverse problems in many applications often involve Partial Differential Equations (PDEs). A Reduced Basis (RB) method for solving PDE based inverse problems is introduced in this thesis. The RB has been rigorously established as an efficient approach for solving PDEs in recent years. In this work, we investigate whether the RB method can be used as a regularization for solving ill-posed and nonlinear inverse problems using iterative methods. We rigorously analyze the RB method and prove convergence of …

Flexoelectricity And Ferroelectric Domain Wall Structures: Phase-Field Modeling And Dft Calculations, Yijia Gu, Menglei Li, Anna N. Morozovska, Yi Wang, Eugene A. Eliseev, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

We show that flexoelectric effect is responsible for the non-Ising character of a 180° ferroelectric domain wall. The wall, long considered being of Ising type, contains both Bloch- and Néel-type polarization components. Using the example of classic ferroelectric BaTiO3, and by incorporating the flexoelectric effect into a phase-field model, it is demonstrated that the flexoelectric effect arising from stress inhomogeneity around the domain wall leads to the additional Bloch and Néel polarization components. The magnitudes of these additional components are two or three magnitudes smaller than the Ising component, and they are determined by the competing depolarization and flexoelectric fields. …

Discrete Strain Engineering In Graphene, Cedric Marcus Horvath

Graduate Theses and Dissertations

Graphene has a number of fascinating mechanical and electrical properties. Strain engineering in graphene is the attempt to control its properties with mechanical strain. Previous research in this area has come up with an approach using a continuum theory to describe the strain induced gauge fields in graphene; however, this approach is only valid for small strains (5% at most). A discrete framework is being developed in Arkansas that can more accurately calculate the deformation (electrical) and (pseudo-)magnetic gauge fields created by large strains. Computational simulations were carried out and used to get discrete atomic positions for strained, suspended graphene …

Homochiral Metal-Organic Materials: Design, Synthetic And Enantioseletive Separation, Shi-Yuan Zhang

USF Tampa Graduate Theses and Dissertations

Owing to the growing demand for enantiopurity in biological and chemical processes, tremendous efforts have been devoted to the synthesis of homochiral metal-organic materials (MOMs) because of their potential applications in chiral separation and asymmetric catalysis. In this dissertation, the synthetic strategies for homochiral MOMs are discussed keeping the focus on their applications. Two distinct approaches have been taken to synthesize chiral structures with different topologies and accessible cavities. The chiral MOMs have been utilized in enantioselective separation of racemates.

Chiral variants of the prototypal metal-organic framework MOF-5, δ-CMOF-5 and [lambda]-CMOF-5, have been synthesized by preparing MOF-5 in the presence …

Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper

Articles

The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with

Study Of The Structure-Property Relationships That Determine The Effects Of Latexes And Starch Containing Latex Emulsions On The Performance Of The Barrier Coatings (Sub-Coat) For Paper, Joanna Marie Monfils

Master's Theses

The history of carbonless paper dates back to the 1940s. Before this, a carbon copy sheet was needed between sheets of paper to be able to produce one or more copies simultaneously during writing. The pressure from a pen or typewriter would help deposit the ink of the carbon paper onto the blank sheet of paper under the original written sheet to create a “carbon copy.” This method did however, have its disadvantages. Not only did it produce a limited number of copies, but it was also a messy process. So came the creative process of using microencapsulated dyes to …

Thermodynamics And Reaction Kinetics During Mechanochemical Synthesis And Environmental Testing Of Lanthanide And Actinide Refractory Materials, Gordon Andrew Alanko

Boise State University Theses and Dissertations

High energy ball milling is a broad family of well-known techniques for materials processing that includes mechanochemical synthesis, in which the milled materials react during milling. The latter may involve components reacting in the solid, liquid, or gas phases, and the operative kinetics have hardly been studied. Several manufacturers of high energy ball mills have recently made available instrumented milling vessel lids. These lids are able to monitor the temperature of the lid and the gas pressure within the vessel in situ during milling experiments. This ability is a significant improvement over the ad hoc instrumentation setups sometimes discussed in …

Optimizing Polymer Fluorescence For Explosives Detection, Rose K. Cersonsky

Honors Scholar Theses

Pyrene is commonly used for explosives detection, as when mixed with polystyrene, the fluorescence intensity of the resulting film can be used as an indicator of the presence of nitro-aromatic, nitro-ether, or nitro-amine explosives. Previous studieshave tested a three-component system including pyrene, polystyrene, and a salt, tetrabutylammonium hexafluorophosphate (TBAHP). From these previous studies, it has been seen that vapor pressure of the preparation area is a governing factor in the formation of excimers, which are instrumental in achieving and maintaining fluorescence intensity. In this study, three parameters – solution concentration, film thickness, and molecular weight of polystyrene are examined to …

Fabrication And Characterization Of Amorphous/Nanocrystalline Thin Film Composite, Benjamin Seth Newton

Graduate Theses and Dissertations

Combining the absorption abilities of amorphous silicon and the electron transport capabilities of crystalline silicon would be a great advantage to not only solar cells but other semiconductor devices. In this work composite films were created using molecular beam epitaxy and electron beam deposition interchangeably as a method to create metallic precursors. Aluminum induced crystallization techniques were used to convert an amorphous silicon film with a capping layer of aluminum nanodots into a film composed of a mixture of amorphous silicon and nanocrystalline silicon. This layer was grown into the amorphous layer by cannibalizing a portion of the amorphous silicon …

Phase Transformations In Calcium Substituted Lanthanum Ferrite, Patrick M. Price

Boise State University Theses and Dissertations

Increasing world energy demands are still heavily dependent on fossil fuels. To meet these demands, crude oil is increasingly being extracted from remote locations where natural gas pipelines do not exist. It is not profitable for oil and gas companies to transport natural gas by ship or truck from these remote locations so it is combusted on site in the form of gas flares. Critics oppose this practice due to the environmental impact from pollution and carbon emissions created during the flaring process. Oil and gas companies are eager to find profitable ways to eliminate natural gas lines in order …

Investigation Of Energy Alignment Models At Polymer Interfaces, Wenfeng Wang

USF Tampa Graduate Theses and Dissertations

The presented study investigated the Induced Density of Interface States (IDIS) model at different polymer interfaces by using photoemission spectroscopy in combination with electrospray deposition.

In recent years, organic electronics have attracted considerable attention due to their advantages of low-cost and easy-fabrication. The performance of such devices crucially depends on the energy barrier that controls the interface charge transfer. A significant effort has been made to explore the mechanisms that determine the direction and magnitude of charge transfer barriers in these devices. As a result of this effort, the IDIS model was developed to predict the energy alignment at metal/organic …

Structural, Magnetic And Microstructural Studies Of Composition-Modified Sm–Co Ribbons, Xiujuan Jiang

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

There is an increasing interest in developing desirable microstructures in hard magnetic materials. Sm-Co-based magnets, bearing superior intrinsic magnetic properties, are good candidates for further development. Two Sm-Co-based alloys, (Sm₁₂Co₈₈)_100-x-yCr_yC_x (taking SmCo₇ phase) and SmCo_4-xFe_xB (a derivative of SmCo₅ phase), were produced using melt-spinning technique. The magnetic properties are correlated to the structural and microstructural properties.

Within the SmCo₇ stoichiometry, cumulative effects of Cr and C additions on the structural and magnetic properties have been investigated. Experimental results have shown that these additions along …

A Sinteractive Ni-Bazr0.8Y0.2O3-Δ Composite Membrane For Hydrogen Separation, Shumin Fang, Siwei Wang, Kyle S. Brinkman, Fanglin Chen

Faculty Publications

BaZr_0.8Y_0.2O_3−δ (BZY) is an excellent candidate material for hydrogen permeation membranes due to its high bulk proton conductivity, mechanical robustness, and chemical stability in H₂O- and CO₂-containing environments. Unfortunately, the use of BZY as a separation membrane has been greatly restrained by its highly refractory nature, poor grain boundary proton conductivity, high number of grain boundaries resulting from limited grain growth during sintering, as well as low electronic conductivity. These problems can be resolved by the fabrication of a Ni–BZY composite membrane with large BZY grains, which requires the development …

Preparation Of Pt/H-Tio2 Catalyst With Improved Catalytic Performance For Methanol Electrooxidation, Jin Han, Zhi-You Zhou, Qiang Wang, Miao-Qiang Lv, Chi Chen, Shi-Gang Sun

Journal of Electrochemistry

White TiO₂ nanorods were synthesized by hydrothermal method with TiCl₄ as a precursor. As-synthesized TiO₂ nanorods were further subjected to high-temperature (550 ^oC) heat treatment for 2 h under H₂ atmosphere to prepare gray black hydrogen-treated TiO₂ (H-TiO₂) nanorods with oxygen vacancies and Ti³⁺ interstitial atoms. The Pt nanoparticles of 1.9 nm were supported on these two types of TiO₂ nanorods to form Pt/TiO₂ and Pt/H-TiO₂ catalysts. XRD data indicates that the crystal structure of TiO₂ was still reserved as rutile after hydrogen treatment, but the surface …

Electro-Catalytic Oxidation Of Hydrogen Peroxide On Au/ L-Methionine /Gc Electrode, Jian-Feng Fan, Xue-Mei Luo, Jing Li, Lou-Zhen Fan

Journal of Electrochemistry

The modified electrodes have been fabricated by generation of Au nanoparticle chains, which was produced by reaction between HAuCl4 and sodium citrate without any additional capping agents or surfactants. The self-assembled Au nanoparticles were attached to the surface of glassy carbon electrode (GCE) layer by layer, using L-methionine (L-Met), thiourea (TU), allyl thiourea (ATU) and polyvinylpyrrolidone (PVP) as a crosslinking agent, respectively. The experimental results showed that the electrochemical performance of the different modified electrodes varied in [Fe(CN)₆]^3-/4- solution. The Au/L-Met/GCE exhibited an excellent electrochemical property, which is superior to other modified electrodes. In addition, the catalysis …

Synthesis Of Platinum Nanocrystallites And Possible Electrocatalytic Properties For Methanol, Lei-Lei Lu, Bao-Zhong Du, Sha Sun, Jin-Fen Niu, Jie Zhao

Journal of Electrochemistry

Platinum nanocrystallites were synthesized by the colloidal method using oxamide as the stabilizer. The morphologies and electrocatalytic performances for methanol of platinum nanocrystallites prepared at different pH values and with different reactant ratios of precursor and stabilizer were investigated. It was found that the platinum nanocrystallites synthesized at pH=5 and with the reactant ratio of 1:20 showed the best electrocatalytic activity for methanol. The peak current density reached up to 1709 μA·cm^-2. Furthermore, the electrocatalytic activity of platinum nanocrystallites for methanol reduced significantly although the cyclic voltammograms in the blank solution were not obviously changed after exposing in …

Effect Of Temperature On The Self-Humidifying Open-Cathode Proton Exchange Membrane Fuel Cell, Si-Chen Zhao, Ben Wang, Qiu-Hong Jia, Ming Han, Yu-Hong Xie

Journal of Electrochemistry

Based on the experiments about the output characteristics of a home-made temperature-controlled PEMFC system with atmospheric pressure and no external humidifying condition in different loading voltages and operating temperatures, the optimum operating temperature at different loading voltages can be obtained by tracking the output characteristics of PEMFC operating over a range of temperatures. By analyzing the fitted data the kinetic parameters are evaluated and the effect of different operating temperatures on the PEMFC performance is discussed from a view of electrode kinetics.

An Equivalent Circuit Model For Redox Flow Battery Stack, Dong-Jiang You, Hua-Min Zhang

Journal of Electrochemistry

This paper introduces an equivalent circuit model for a redox flow battery stack. The model combines the electrochemical reaction of the battery cell and the shunt current of the battery stack. An all-vanadium redox flow battery stack of 1kW rated output power is tested through transient response and self-discharge experiments. All the parameters used for the modeling are obtained. Calculated shunt current and distribution of calculated battery voltage are shown in the results. It is concluded that the impedance of the battery stack can be obtained by the experimental results of the transient response and self-discharge measurements. The capacity lose …

Electrocatalytic Oxidation Of Glycerol At The Platinum Electrode Modified With An Nd-Fe-Moo42- Cyano-Bridged Mixed Coordination Polymer, Yong-Jun Ma, Yu-Xiu Tian, Jing Liu, Min Zhou, Jing Ding, Zhi-Mei Jin, Xiang-Mei Wang

Journal of Electrochemistry

A platinum electrode decorated with the ordered Nd-Fe-MoO₄^2- cyano-bridged mixed coordination polymer was successfully prepared by electrodeposition in virtue of the lyotropic liquid crystal soft template methods, and electrocatalytic oxidation behavior of glycerol was investigated on the chemically modified electrode by cyclic voltammetry. The influences of experimental factors such as the concentrations of H⁺ and SO₄^2- in electrolytes, glycerol concentration and scan rate on the electrocatalytic activity of glycerol at the modified electrode were also studied. It indicated that the proper amount of SO₄^2- in weakly acidic electrolyte could help to improve the …

Electrodeposition Of Copper From A Choline Chloride Based Ionic Liquid, Rostom Ali M., Ziaur Rahman Md., Sankarsaha S.

Journal of Electrochemistry

The electrodeposition of copper from a solution containing copper chloride in either an ethylene glycol (EG)-choline chloride based or a urea-choline chloride based ionic liquid has been carried out onto a steel cathode by constant current and constant potential methods at room temperature. The influences of various experimental conditions on electrodeposition and the morphology of the deposited layers have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is shown that very smooth, shiny and dense with good adherence and bright metallic coloured copper coatings can be obtained from both EG and urea based ionic liquids at …

Application Of Ionic Liquid Pp14Tfsi In Electrolyte Systems For Rechargeable Mg Batteries, Jin-Jie Zhu, Fei-Fei Wang, Yong-Sheng Guo, Jun Yang, Yan-Na Nuli, Jiu-Lin Wang

Journal of Electrochemistry

A phenolated-based Mg salt was prepared. The mixture of THF and N-methyl-N-butyl-piperidinium bis(trifluoromethanesulfonyl)imide (PP14TFSI) serves as the mixed solvent instead of pure THF for rechargeable Mg batteries systems. This new type of electrolyte system not only has optimal reversibility of Mg, but also owns a wide electrochemical window (2.7 V vs. Mg) and high ionic conductivity (7.77 mS·cm^-1). More importantly, the addition of Ionic Liquid suppresses the volatility of THF and improves the safety of rechargeable Mg batteries. The result shows that the mixture of THF and piperidyl-based Ionic Liquid could be regarded as a good solvent candidate …

Preparation And Electrochemical Performances Of Cofe2O4/Gns Nanocomposites As Anode Material For Lithium Ion Battery, Mo-Chao Cai, Sen-Rong Cai, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The CoFe₂O₄/GNS was synthesized by a simple one-pot solvothermal method. The results obtained by X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that the CoFe₂O₄ particles with sizes of 15 nm dispersed on the surface of graphene uniformly. Electrochemical tests indicated that the CoFe₂O₄/GNS nanocomposite exhibited excellent cyclic stability with almost 95.8% capacity retention after 100 cycles at the current density of 500 mA·g^-1 and delivered a high reversible capacity of 482 mAh·g^-1 at the current density of 2 A·g^-1.

Effects Of Carbon Interlayer On Electrochemical Performance Of Lithium-Sulfur Cell, Jin-Peng Yu, Ming Zhang, Fei Ding, Zhi-Yuan Tang, Xing-Jiang Liu

Journal of Electrochemistry

Three kinds of conductive carbon films were prepared with Super-P (SP), KB and MWCNTs, and then the as-prepared carbon films were applied as an interlayer between a sulfur electrode and a separator for constructing a coin-type lithium-sulfur (Li-S) cell, respectively. The assessment results show that all the cells delivered the reversible capacities higher than 800 mAh·g^-1 after 40 cycles when the sulfur loading was up to 80% (by mass) in the sulfur electrode. Due to significant differences of physical properties among the carbon materials, the cell with a KB interlayer exhibited higher electrochemical polarization; the cycling performance of the …

Effect Of Al-Doping In Li-Rich Material Li1.2Mn0.543Co0.078Ni0.155Al0.030O2 For Lithium-Ion Batteries, Xiao-Xi Jin, Yi-Xiao Li, Yong Yang, Zhou-Cheng Wang

Journal of Electrochemistry

The Al-doped 0.5Li₂MnO₃·0.5Li(Mn_0.4Co_0.2Ni_0.4)O₂ compounds were successfully synthesized as cathode materials for lithium-ion batteries. The pristine and Al-doped materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and laser Raman spectroscopy. The results indicated that all the prepared materials were indexed as a hexagonal structure with R-3m space group, and Al element had been introduced into lattice. When cycled at 180 mA·g^-1 (1 C-rate), the capacity retention of 4% (by mole) Al-doped 0.5Li₂MnO₃·0.5Li(Mn_0.4Co_0.2Ni …

3d Printing Of Stainless Steel For Engineering Applications, Michael Doyle

Undergraduate Research Symposium

3-D metal printing has the potential to solve problems in the medical, prototyping, automotive, aerospace, defense, and other engineering industries. To reach the potential of any manufacturing process, the final product’s material characteristics and how the process affects those characteristics must be understood to meet the demands of industrial applications. There is a gap in standard testing information regarding metal based 3-D metal printing processes. The purpose of this research is to fill that gap of valuable information for this manufacturing process, so that its principles can be used to design better products. Fundamental tensile and compression tests were executed …

Magnetic Shape Memory Micro-Pump For Intra-Cranial Drug Delivery, Sam Barker, Eric Rhoads, Andrew Morrison, Miranda Buttram, Paul Lindquist

College of Engineering Presentations

Magnetic shape-memory alloys exhibit strong magneto-structural coupling enabling large magnetic-field-induced deformation. Local control of twinning via variable inhomogeneous magnetic fields initiates local reversible deformation. Previous work produced a valve-less micropump consisting of a Ni-Mn-Ga single crystal, a casing, and a rod magnet. The micropump successfully pumped fluid in opposite directions when the magnet was turned clockwise and counter clockwise. Our current work modifies this micropump for application in rat a head stage, which would simultaneously monitor electroencephalograph data and deliver 0.5-5.0 μl of a drug solution at 100-500 nl/min directly to the rat’s brain. These improvements and the application of …

Molecular Modification Of Cnt Junctions, Kari Mclaughlin*, Hanna Meinikheim*, Angela "Nikki" Chang

College of Arts and Sciences Presentations

Carbon nanotube networks (CNNs) are increasingly finding applications as thin film transistors (TFTs), integrated circuits, and display drivers on flexible, transparent substrates. This is attributed to the higher carrier mobility of CNNs as compared to amorphous silicon and organic TFTs [1,2]. However, high electrical [3-5] and thermal [6,7] resistances at individual nanotube junctions (NJs) limit the performance of CNN devices. The resistances of the junctions are no less than an order of magnitude higher than those of individual carbon nanotubes (CNTs). This causes high power dissipation at the NJs. In the end this causes degradation of the overall device performance …

The Properties And Structure Of Zinc Magnesium Phosphate Glasses, Charmayne E. Smith (Lonergan), Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Zn-Mg-phosphate (ZMP) glasses, including those with the nominal molar compositions (50 - x)ZnO xMgO 50P₂O₅ (0 ≥ x ≥ 50) and (60 - y)ZnO yMgO 40P₂O₅(0 ≥ y ≥ 60), were prepared and properties such as density, refractive index, coefficient of thermal expansion and glass transition temperature (Tg), were measured. The glass transition temperature increases by 100-150 C and the room temperature dissolution rates in water decrease by 1-2 orders of magnitude when MgO replaces ZnO while maintaining a constant P₂O₅ content. Glass structures were characterized by Raman spectroscopy and …

Effect Of Ionic Crosslinking On The Swelling And Mechanical Response Of Model Superabsorbent Polymer Hydrogels For Internally Cured Concrete, Qian Zhu, Christopher W. Barney, Kendra Erk

School of Materials Engineering Faculty Publications

The chemical and physical structure-property relationships of model superabsorbent polymer (SAP) hydrogels were characterized with respect to swelling behavior and mechanical properties in different ionic solutions (Na+, Ca2+, and Al3+). The model hydrogels were composed of poly(sodium acrylate-acrylamide) (PANa-PAM) copolymer with varying concentrations of PANa (0, 17, 33, 67, and 83 wt.%) and covalent crosslinking densities of 1, 1.5, and 2 wt.%. By synthesizing the hydrogels in-house, systems with independently tunable amounts of covalent crosslinking and anionic functional groups were created, allowing for the relative effects of covalent and ionic crosslinking on the properties of the hydrogels to be directly …

Simulation Of The Relaxation Potential Profile Of An Ac-Dc-Ac Test, Kerry N. Allahar, Michael F. Hurley, Erik D. Sapper, Darryl P. Butt

Materials Science and Engineering Faculty Publications and Presentations

The relaxation period of the accelerated ac-dc-ac test for coatings is associated with the transient electrochemistry that occurs when the immersed coated system is allowed to return to a stable open-circuit condition after being subjected to a cathodic potential. A mathematical model of the transient electrochemistry that occurs during this relaxation period is presented for coated aluminum. Expressions for the corrosion potential and corrosion current as functions of the local pH at the metal-coating interface were developed using reported experimental results. These expressions enabled the simulation of the transient electrochemistry under the constraint of balanced anodic and cathodic current densities. …