Materials Science and Engineering Commons^™

Computational Studies Of Electronic Structure Of Doped Graphene, Yan Chu

Theses

In the literature, extensive studies have been performed to study the electronic properties of doped graphene. This is due to the potentially large number of applications of graphene in p-n junctions, transistors, photodiodes and lasers. By utilizing single heteroatom chemical doping method or electric field-induced method, one can introduce a band gap, ranging from 0.1eV to 0.5eV, in graphene. A tunable bandgap is highly desirable because it would allow significant flexibility in the design and optimization of such devices, particularly if it could be tuned by adjusting the doping configurations. Here, we demonstrate the realization of a widely tunable electronic …

Modeling Of Electrical Behavior Of Graphene-Based Ultracapacitors, Patrick Dzisah

Theses

Graphene has been identified as a promising material for energy storage, especially for high performance ultracapacitors. Graphene-based ultracapacitors show high stability, significantly-improved capacitance and energy density with fast charging and discharging time at a high current density, due to enhanced ionic electrolyte accessibility in deeper regions. The surface area of a single graphene sheet is 2630 m2/g, substantially higher than values derived from Brunauer Emmett Teller (BET) surface area measurements of activated carbons used in the current electrochemical double layer capacitors.

In an ultracapacitor cell, chemically modified graphene (CMG) materials demonstrate high specific capacitances of 135 and 99 F/g in …

Design, Construction And Characterization Of A Wind Tunnel, Chang Ge

Theses

The wind tunnel is the most fundamental test equipment for aircraft testing and studying aerodynamics. Because of the complexity of the test-subject's geometry, it is difficult to study the aerodynamic pattern simply based on theoretical calculations. Most of the aerodynamics experiments still use wind tunnels. The progress of the wind tunnel is highly related to the advancements in air crafts. Aircraft manufacturing has pushed the wind tunnel technology forward. Wind tunnels can be categorized by the wind speed limit differences, which are controlled by the mechanism of the driving methods, structure applications, etc. In this case, we built a small …

Simulation Of Electronic And Optical Properties Of Graphene, Biao Leng

Theses

Graphene is a recently discovered two-dimensional crystal. Due to its excellent electronic properties, transport properties, optical properties, and many other features, it has tremendous potential for applications in many areas. This thesis discusses the structure and properties of graphene using several different models of graphene and carries out detailed theoretical studies and calculations of its electronic and optical properties. Using two modules of Materials Studio, CASTAP and Doml3, four graphene models have been constructed. Their electronic and optical properties have also been calculated via these two modules. By comparing the results of calculations with experimental results and the literature, the …

Thermal Properties Of Graphene, Vishal Vijay Nakhate

Theses

The two-dimensional (2D) monolayer structure of carbon atoms were initially considered as unstable. The 2D materials have recently been discovered and many researchers have started analyzing these materials. Graphene, a two-dimensional allotrope of graphite with sp2 bonded carbon atoms, is arranged in honeycomb structure. Graphene has excellent thermal conductivity and can be considered as a potential material for applications in the electronics industry where heating of materials is a serious concern.

In this study, thermal properties of p and n doped graphene nanosheets and nanoribbons are studied as function of percentage composition of the dopants and the direction of dissipation …

Processing And Characterization Of Graphene And Graphene On Silicon, Cheng Peng

Theses

Graphene has become a promising material for applications in many areas including electronic devices, batteries and space crafts. Although it has a bright future, the commercial production of graphene has not yet been realized. In this thesis, an overview of the properties and applications of graphene is presented. The early research of preparing graphene and its composites is summarized, which gives the basis to synthesize graphene and improve the process. In this study, graphene oxide (GO) and graphene have been successfully made using graphite; graphene layer has been coated on the surface of a silicon wafer. The resulting specimens are …

Design, Construction And Characterization Ofa Magnetic Augmented Rotation System (Mars) Based Wind Turbine, Da Li

Theses

Magnetic Augmented Rotation System (MARS) works by magnetic field coupling, to transfer torque from the driver to the rotor without contact. This characteristic has significant applications to the wind turbine but research in combination of MARS and wind turbine has not been done in the literature. In this thesis, a small-scale wind turbine is designed, built and characterized in a prototype wind tunnel. The test results are analyzed and computer-aided software simulation is used as an auxiliary method to understand the mechanism of MARS. The power coefficient of this new wind turbine is estimated to be about 40%. The “gear …

Ultracapacitors For Off Grid Wind Power Systems, Hans Tanis

Theses

The main reason for wind turbine to be not as prevalent as traditional power systems is because they do not have an effective storage capacity. However, researchers in material science and engineering have found ways to resolve this problem by developing “ultracapacitors” that store energy by assembling ions at the surface of a porous material. That is why ultracapacitors coupled with the energy storage battery could present a challenge to the electrical power grid. Such a design allows ultracapacitors to charge in matter of minutes and not hours. This innovation would create a significant impact on electronic items such as …

Bio-Medicinal Application For Plasma Electrolytic Oxidation Of Metals, Zunjian Yang

Theses

Plasma electrolytic oxidation (PEO), a novel method for forming ceramic coatings on metals, has been researched extensively in recent times. By applying high voltage between dielectric thin films, a plasma micro-arc is induced through penetration of breakdown in film boiling layer. Such a method takes advantage of high processing time, low equipment requirement and advanced coating performance.

Titanium alloys, Ti-6Al-4V and pure Titanium Grade 2, are two of most common Titanium alloys in daily use. Both of such Titanium alloys show great potential utilization in bio-medicinal application, especially in implants, for its excellent biocompatibility, high tensile strength, and high elastic …

Optical Properties Of Black Silicon - An Analysis, Suramya Sekhri

Theses

Silicon is the preeminent solar cell material of the day because it is the first semiconductor that was learned to commercialize and continues to be the principal semiconducting material used in photovoltaic technology for the manufacture of solar cells. Silicon, an indirect band gap semiconducting material, has a reflectance of about 30% in the visible range of wavelengths. Standard Silicon solar cells are not entirely useful in the infrared spectrum region. In order to enhance the performance of Silicon solar cells, reflectance losses must be minimized and absorption must be maximized. In the solar cell industry, anti-reflection (AR) coating is …

Capacitance Measurements Of Defects In Solar Cells: Checking The Model Assumptions, Justin R. Davis

Senior Theses

Capacitance measurements of solar cells are sensitive to minute changes in charge in the material. For that reason, capacitance is used in several methods to electrically characterize defects in the solar cell. Standard interpretations of capacitance rely on many assumptions, which, if wrong can skew the results. We explore possible alternative explanations for capacitance transitions, such as a non-ideal back contact and series resistance. Using Drive Level Capacitance Profiling measurements, a capacitance step is linked to a defect between the energy bands of a solar cell.

Predictive Modeling Of Oxygen Transmission Through Micro-Perforations For Packaging Applications, Ayman Abdellatief, Bruce A. Welt, Jason Butler, Eric Mclamore, Arthur Teixeira, Sanjay Shukla

Journal of Applied Packaging Research

Methods for creating precise perforations in respiring produce packaging are being increasingly adopted. Knowledge of oxygen transfer through perforated packaging and oxygen distribution in packages is necessary for successful packaging design of fresh produce. An approach to modeling perforated packaging performance was developed using a cylindrical chamber with precision perforations using Fick’s second law. The model was simulated using two techniques including Finite Element Method (FEM) using commercially available software and Finite Volume Method (FVM) through programming. Perforations were approximated as a source term in the second method. Both simulation techniques showed trends similar to experimental data.

Constant Interface Temperature Reliability Assessment Method: An Alternative Method For Testing Thermal Interface Material In Products, Christian Amoah-Kusi

Dissertations and Theses

As electronic packages and their thermal solutions become more complex the reliability margins in the thermal solutions diminish and become less tolerant to errors in reliability predictions. The current method of thermally stress testing thermal solutions can be over or under predicting end of life thermal performance. Benefits of accurate testing and modeling are improved silicon yield in manufacturing, improved performance, lower cost thermal solutions, and shortened test times.

The current method of thermally stress testing is to place the entire unit in an elevated isothermal temperature and periodically measure thermal performance. Isothermally aging is not an accurate representation of …

Measuring Strain In Trusses, Spencer Metzsch

Senior Theses

Strain is an important quantity in engineering design and materials science that relates the deformation of a material to its original length, through a percentage. Different materials exhibit particular qualities under loading, for example the amount of strain due to a certain magnitude of force, or the amount of strain that can be borne before failure. This experiment aims to compare the relative strengths of three common truss configurations by measuring the strain in their members under loading. The Queen’s post truss was found to be the best at minimizing strain under similar loading conditions.

Photocatalytic Mineralization Of Phenol On Fluidized Titanium Oxide-Coated Silica Gel, Guillermo J. Rincon

LSU New Orleans Theses and Dissertations

A bench-scale tubular reactor with recirculation was built in order to study the efficiency of the photocatalytic oxidation of phenol on fluidized titanium oxide-coated silica gel beads. A UV-C lamp placed along the central vertical axes of the reactor was used as source of photons. A bed of silica gel beads was fluidized by means of fluid recirculation and forced to follow upward helical flow around the lamp. Anatase was successfully synthetized on silica gel particles of average diameters 224, 357 and 461 µm, as confirmed by scanning electron micrographs, through a sol-gel technique using a titanium (iv)isopropoxide / hydrochloric …

Synthesis, Characteristics, And Material Properties Dataset Of Bi:Dyig-Oxide Garnet-Type Nanocomposites, M Nur-E-Alam, Mikhail Vasiliev, Kamal Alameh

Research outputs 2014 to 2021

The fabrication, annealing crystallization processes, and material properties of (Bi,Dy)3(Fe,Ga)5O12:Bi2O3 nanocomposites are investigated and summarized. The stoichiometry of these nanocomposites is optimized for magnetooptic applications using the approach of stoichiometry adjustment (implemented by means of varying RF power densities applied to the sputtering targets used to prepare the nanocomposite thin films). The crystallization processes for all developed batches of as-deposited films are carried out by annealing runs at different temperatures and process durations. This paper describes the methodologies used to optimize the compositions (by calculating the volumetric fractions of excess bismuth oxide to be mixed with the garnet-stoichiometry species during …

On The Fe Enrichment During Anodic Polarization Of Mg And Its Impact On Hydrogen Evolution, D. Lysne, S. Thomas, M. F. Hurley, N. Birbilis

Materials Science and Engineering Faculty Publications and Presentations

Iron (Fe) is an unintentional impurity present in pure magnesium (Mg) and Mg alloys, albeit nominally in low and innocuous concentrations (< 100 ppmw). Since Fe, like most metals, is more noble than Mg, the presence of Fe impurities can serve as cathodic sites within the Mg matrix. During anodic polarization of Mg, incongruent dissolution can lead to undissolved Fe impurities accumulating upon the Mg surface, permitting an increase in the overall rate of hydrogen evolution. The experimental manifestation of the incongruent dissolution of Mg, has not yet been clarified, wherein, the extent and efficiency of Fe enrichment during anodic polarization is not known, and also the increase in the hydrogen evolution rate due to Fe enrichment has not been quantified. In this work, Mg specimens with Fe concentration between 40 to 13,000 ppmw were examined in 0.1 M NaCl to obtain a quantitative relation between the Fe concentration and the rate of cathodic hydrogen evolution. These base-line alloys were then anodically polarized to facilitate surface Fe enrichment, and subsequently again cathodically polarized to determine the impact of prior dissolution and Fe enrichment on the subsequent hydrogen evolution. A simple model to predict Fe enrichment was used to analyze the electrochemical data and predict the extent and efficiency of Fe enrichment.

Three-Dimensional Printing Of Graphene-Based Composite Aerogels, Chen Zhu

Composites at Lake Louise (CALL 2015)

Graphene-based composite materials have found wide applications in nanoelectronics, sensors, catalysis, energy storage, and biomedicine areas for their unique combination of low density, exceptional mechanical properties, large surface area, and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, by the self-assembly or gelation of the graphene oxide (GO) suspension via hydrothermal reduction, chemical reduction, or direct crosslinking of the GO sheets. Other templating methods like chemical vapor deposition (CVD) coatings and freeze-casting have already been employed to control over the pore morphology of 3D graphene monoliths. However, the architecture of these graphene …

Feasibility Study: The Evaluation Of Polymer Coatings To Prevent Weathering Of Weak Rocks, Lauren Distler

Senior Honors Projects, 2010-2019

The weathering and erosion of weak rocks along roadways can cause dangerous and potentially fatal rockfalls.   Various slope stabilization methods exist, but each presents a set of challenges and trade-offs.   The focus of the project is to understand the feasibility of utilizing of a polymerbased slope stabilization technique. Rock samples were collected along US Route 33 in Virginia and West Virginia, and preliminary tests were conducted to evaluate the absorption of water (% mass) and durability. The study evaluates three polymer options in regard to the following criteria: adhesion to rock, layer thickness, semi-permeability, insolubility, and non-toxicity. The polymer selection …

Variability In The Fabrication Process Of Bivo4 Photoanodes, Lauren M. Phillips

Senior Honors Projects, 2010-2019

Hydrogen gas produced from the photoelectrochemical (PEC) decomposition of water, using sunlight as an energy source, is a promising approach for sustainable fuel production. This decomposition of water is also called artificial photosynthesis. A device that accomplished this process is sometimes call an artificial leaf, which mimics nature inasmuch as it stores solar energy as a chemical fuel (e.g., hydrogen) by splitting water, in this way imitating natural photosynthesis. In 2009, Dr. Keith Holland and Dr. David Lawrence of James Madison University (JMU) initiated a research program to investigate materials for the photoelectrochemical decomposition of water into hydrogen and oxygen, …

Enhancing Grain Refinement Of Austenitic Steel With Ti Additions By Melt Treatment Sequence Optimization, Gun Ge, Semen Naumovich Lekakh, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Measuring The Effect Of Vegetated Roofs On The Performance Of Photovoltaic Panels In Combined Systems, Hamid Hawi Kadham Ogaili

Dissertations and Theses

Recent studies suggest that integration of photovoltaic panels with green roofs may improve the performance of both. While vegetation may provide a benefit by reducing the net radiation load on the underside of the photovoltaic (PV) panels, it may also affect convective cooling of panels, and consequently, panel efficiency. Both effects likely diminish with the height of the PV panel above the roof, although placing PV panels too close to the vegetation increases the risk of the plants growing over the edges of, and shading the PV panel. There is a gap in the literature with respect to evaluating these …

Section Abstracts: Astronomy, Mathematics And Physics With Material Science

Virginia Journal of Science

Abstracts of the Astronomy, Mathematics, and Physics with Material Science Section for the 93rd Annual Meeting of the Virginia Academy of Science, May 21-23, 2015, James Madison University, Richmond, Virginia

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 …

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 …

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 …

Characterizing Water As Gap Fill For Double Glazing Units, Bright Adu

Masters Theses & Specialist Projects

The use of sunlight has always been a major goal in the design and operation of commercial buildings to minimize electrical consumption of artificial lighting systems. Glazing systems designed to allow optimal visible light transmission also allow significant unwanted direct solar heat gain caused by infrared light. Conversely, glazing systems that are designed to reflect unwanted direct solar heat gain significantly reduce the transmittance of visible light through windows. The goal of this research was to characterize the performance of water as gap-fill for double-glazing units in eliminating the compromises that exist in current glazing systems with respect to light …

Ultrahigh Density Sub-10 Nm Cobalt Nanowire Arrays: Simulation, Fabrication, And Characterization, Yuan Tian

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

The simulation, fabrication, and characterization of self-assembled ultrahigh density sub-10nm Co nanowire arrays are presented in this dissertation. The general phase separation nanowire growth simulation was operated based on a modified Ising model. The fabrication process can be summarized as the binary Co-X systems lateral phase separation during physical vapor deposition – the plasma layer deposition with a single alloy Co-X target. The “X” stands for Al or Si. The nanowire fabrication and diameter deduction was achieved by balancing the growth rate and surface diffusivity. For Co-Al binary system, the formed sub-10 nm Co nanowires are of face-centered cubic structure …

Eye Tracking Consumer Purchase Behavior Within Physical And Virtual Environments, David Andrew Stone

All Theses

Understanding how consumers observe and make purchase decisions within a retail context is now both accessible and efficient through the process of eye tracking. Eye tracking package design aesthetics helps us understand and predict what consumers are looking at, and how likely a package might be selected. Typically, this research is conducted in an immersive retail setting where consumers can shop as they would in a normal store-shopping context. A store is stocked with products where a participant in the study shops throughout while wearing an eye tracker to gather data on what their attention fixates on within a given …

Reaction Kinetics Of Rare Earth And Actinide Materials, Brian Jon Jaques

Boise State University Theses and Dissertations

This dissertation presents the effects of atmosphere, time, and energy input (thermal and mechanical) on the kinetics of gas-solid and solid-solid reactions in systems of dysprosium, uranium, oxygen, and nitrogen. Accordingly, Chapter Two presents a novel synthesis technique used to form DyN via a gas-solid reaction between dysprosium and nitrogen. DyN was rapidly formed through a mechanochemical process in a high energy ball mill at ambient temperatures. The progress of the reaction was quantified using in situ temperature and pressure measurements coupled with microscopy and x-ray diffraction. It was found that the rate of the nitridation reaction is controlled by …