Electrical and Computer Engineering Commons^™

Molecular Dynamics Study Of Characterization In Metal-Free Friction Materials, Yizhan Zhang

Electronic Theses and Dissertations

Metallic friction materials currently used in industry may adversely impact the environment. Substitutions for metals in friction materials, on the other hand, can introduce operational safety issues and other unforeseeable issues such as thermal-mechanical instabilities and insufficient strength. In view of it, this dissertation focuses on developing different kinds of materials from simple structure to complex structure and evaluating the material properties with the assistance of molecular dynamics (MD) tools at the nano scale.

First, the concept of the contacted surfaces in friction at the atomic scale was introduced in order to get accurate understanding of the friction process compared …

The Modernization Of Large Power Transformer Tanks, Babajide O. Williams

Electronic Theses and Dissertations

Due to the current demands placed on the power grid in terms of climate change, increasing urbanization, and terrorist attacks, the U.S. government in response to these demands, mandated that all the grid components be modernized in order to increase their reliability. As a critical component of the grid, Large Power Transformers (LPTs) play a key role in ensuring sustainable power generation and distribution. A literature search performed in this work and the analysis of data retrieved from the search showed that the tanks of these LPTs are critical to their durability, longevity, and reliability. Therefore, the reliability of LPTs …

The Study Of Corrosion On Additive-Manufactured Metals., Braydan Daniels

Electronic Theses and Dissertations

The purpose of this study was to investigate and compare the corrosion mechanisms between wrought and additive-manufactured (3D-printed) copper and stainless steel. The experimental procedure consisted of measuring the open circuit potential, electrochemical impedance spectroscopy, linear sweep voltammetry, Tafel analysis, surface topology, and scanning electron microscopy for each metal within salt water, tap water, sulfuric acid, and synthetic body fluid (excluding copper in synthetic body fluid).

Overall, printed stainless steel was more corrosion-resistant than wrought stainless steel in tap water and synthetic body fluid based on OCP, LSV, and surface topology results. Additionally, printed copper was more corrosion-resistant than wrought …

Optimization Of Chemical Compositions Of Al-Si-Cu-Ni-Sr Alloys With High Strengths And Electrical Conductivities, Yuxian Li

Electronic Theses and Dissertations

Mechanical strengths and electrical conductivity are the very important engineering properties of lightweight metallic materials used in the automotive industry, especially for battery-powered electric vehicles (BEV). However, the main issue is that high strength and high electrical conductivity are mutually exclusive due to physical nature of these properties. The aim of this study is to develop new cast aluminum alloys for the production of rotor bar in the rotor with high as-cast strength and electrical conductivity. A design of experiment (DOE) technique, Taguchi method, was used to develop high as-cast strength and electrical conductivity alloys with various element addition of …

Quality Assurance Of Lightweight Structures Via Phase-Based Motion Estimation, Ikenna E. Ifekaonwu

Electronic Theses and Dissertations

In recent years, lightweight structures have become mature and adopted in various applications. The importance of quality assurance cannot be overemphasized hence extensive research has been conducted to assess the quality of lightweight structures. This study investigates a novel process that exploits motion magnification to investigate the damage characteristics of lightweight mission-critical parts. The goal is to assure the structural integrity of 3D printed structures and composite structures by determining the inherent defects present in the part by exploiting their vibration characteristics. The minuscule vibration of the structure was recorded with the aid of a high-speed digital camera, and the …

Fabrication Of Silicon Microneedles For Dermal Interstitial Fluid Extraction In Human Subjects, Caleb A. Berry

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for silicon microneedle arrays to extract dermal interstitial fluid (ISF) from human skin. ISF is a cell- free, living tissue medium that is known to contain many of the same, clinical biomarkers of general health, stress response and immune status as in blood. However, a significant barrier to adoption of ISF as a diagnostic matrix is the lack of a rapid, minimally invasive method of access and collection for analysis. Microfabricated chips containing arrays of microneedles that can rapidly and painlessly access and collect dermal ISF for …

Two-Dimensional Nanomaterials And Their Composites For Electrochemical Detection Of Toxic Mercury Ions In Water, Md Tawabur Rahman

Electronic Theses and Dissertations

The presence of trace amounts of mercury ion (Hg²⁺) in drinking water has a detrimental effect on human health. The development of an electrochemical sensor for Hg²⁺ detection is still challenging to obtain ultra-trace sensitivity, excellent selectivity, wide Linear Detection Ranges (LDRs), and ultra-low detection limit. This work presents an electrochemical sensor based on two-dimensional nanomaterials and their composites for the enhanced sensing of Hg²⁺ in water. Graphene oxide (GO)-silver nanowires (AgNWs) composite and metallic 1T phase tungsten disulfide (WS2) microflowers were utilized for the fabrication of electrochemical sensors using drop-casting. Under the optimized experimental conditions, …

Surface And Structure Engineering For Next Generation Lithium Metal Batteries, Ke Chen

Electronic Theses and Dissertations

Lithium (Li) metal has been considered as one of the most promising anode materials to replace conventional graphite for Li-ion battery due to its high theoretical capacity (3860 mAh g-1) and low electrochemical potential (-3.04 V vs standard hydrogen electrode). However, it still faces some problems such as unstable solid electrolyte interphase (SEI), uncontrolled Li dendrites growth, and infinite volume change during battery charging/discharging. To develop a stable and low-cost Li metal anode for next-generation Li metal battery, in this dissertation, we have made efforts to understand and solve these problems in two aspects, by introducing an artificial SEI and …

Ultrasonic-Based Condition Assessment Of Wooden Utility Poles, Yishi Lee

Electronic Theses and Dissertations

More than 300 million utility poles shoulder the utility grid in the United States. However, the ineffectiveness of the current inspection process causes roughly a third of utility poles removed from the service deemed suitable for reuse. Due to the utterly essential role of the power infrastructure, budget shrinkage, and the structural degradation of the modern distribution grid, this Ph.D. dissertation addresses the challenges by proposing a physics-based signal analysis method with a jointly developed ultrasonic UB1000 system c to enhance the objectivity in ultrasonic-based nondestructive evaluation (NDE). The proposed methodology has been deployed commercially in the field and featured …

Triple-Junction Solar Cells : In Parallel., Levi C Mays

Electronic Theses and Dissertations

This paper looks into the current inefficiency of solar cells and attempts a few alternative solar cell structures in order to provide a more effective source of renewable energy. Currently, multi-junction solar cells are being developed to capture the sun’s light more efficiently. One of the ideas in this paper is to add a window to see if the addition of such a layer into a junction will increase the voltage while maintaining nearly the same current output. Central to this paper is the rearranging of the conducting layers of the multi-junction cell so that the junctions can be connected …

Metal Thin Film Stiffness Extraction Technique For Surface Acoustic Wave Filters, Travis R. Weismeyer

Electronic Theses and Dissertations

Accurate knowledge of the surface acoustic wave (SAW) properties propagating at the surface of a piezoelectric substrate with thin films, electrodes or temperature compensated films, is critical in SAW filter design to meet the target frequency response, power durability and performance prior to device fabrication. While reliable material constants exist for substrates such as LiNbO3 used in SAW filters, the absolute elastic constants associated with operational thin films used for electrodes or temperature compensation do not exist. Although the bulk values of the constituent materials are known, the composite film/substrate properties are difficult to predict since they depend strongly on …

Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for a silicon photovoltaic device which incorporates a nanohair textured p-n junction. The silicon nanowires are etched into a silicon wafer, comprising an epitaxial p-layer on n-substrate, via metal-assisted chemical etching (MACE). The resulting nanowires contain p-n junctions that lie along the length of the vertical nanowires. This construct has the potential to increase the optical bandwidth of a silicon photovoltaic device by allowing a greater amount of short wavelength light to reach the junction. In addition, the MACE method of nanofabrication has the potential for decreasing …

High Dynamic Range Optical Devices And Applications., Elijah Robert Jensen

Electronic Theses and Dissertations

Much of what we know about fundamental physical law and the universe derives from observations and measurements using optical methods. The passive use of the electromagnetic spectrum can be the best way of studying physical phenomenon in general with minimal disturbance of the system in the process. While for many applications ambient visible light is sufficient, light outside of the visible range may convey more information. The signals of interest are also often a small fraction of the background, and their changes occur on time scales so quickly that they are visually imperceptible. This thesis reports techniques and technologies developed …

Electro-Magnetic Responsive Ni0.5zn0.5fe2o4 Nano-Particle Composite, Jaiprakash Kanagaraj

Electronic Theses and Dissertations

The purpose of this study is to simulate and synthesize a Radar (or Radiation) Absorbent Material (RAM) by using polymers and nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) magnetic nanoparticles. There is an ardent desire in military, space and electronics for lighter, faster, cheaper and widespread bandwidth providing RAM materials. Electromagnetic property such as magnetic permeability and electric permittivity play a major in controlling the radiation. The appropriate combination of permeability and permittivity properties is acquired for the synthesis of RAM providing wide-ranging bandwidth. The apt property is achieved by rule of mixture, mixing of particular composition of epoxy polymer having low permeability …

Novel Technique Of Fabrication Of Porous Copper And Copper Oxide To Improve The Lithium Ion Battery Performance, Raju Prasad Ghimire

Electronic Theses and Dissertations

Due to widespread and long-term application, Lithium-ion batteries are considered as promising power sources for portable devices, satellites, medical instruments, computers, electric vehicles and grid application. It started to occupy the market once Sony commercialized in 1991. Rechargeable lithium ion batteries drawing people attention due to their peculiar properties such as high energy density and low self-discharge compared to other alkali metals. However, these widespread and long-term applications still require better batteries in terms of performance, safety and cost, which can be achieved by better utilization of anode materials and/or an optimized design of battery configuration. There are several challenges …

Control Of Pore Characteristics Of Porous Silicon Using Non-Toxic Electrochemical Etching For Photovoltaics And Supercapacitor Applications, Utpal Saha

Electronic Theses and Dissertations

Porous silicon has exhibited lower reflectance and higher surface area than the pristine silicon. This property of porous silicon can be applied to photovoltaic (PV) application for more efficient silicon solar cells and for higher performance of supercapacitors. NH4Fl electrolytic etching solution has been used to fabricate porous silicon, but the control of pore morphology of silicon is achieved only by controlling the time. Therefore, it is urgently required to use other etching parameters such as voltage and current to achieve flexible control of pore properties. Porous silicon can also be used to fabricate supercapacitors. An established approach to make …

Development Of Highly Sensitive And Selective Breathing Sensors Using Molecular Imprinted Filtering For Diabetic And Alcoholic Patients, Md. Saleh Akram Bhuiyan

Electronic Theses and Dissertations

Wellness sensor technology is an emerging diagnostic test research field, which mostly deal with the point of care of the patients in the recent days. Due to the lack of awareness from the patients, most diseases cannot be detected in due time. This led to worse conditions, such as diabetic and alcoholic syndrome. Therefore, many research groups have been working to develop portable sensor devices that can track serious diseases. These include diabetic and alcoholic biomarkers in breathing. These devices have very high selectivity and reliability. However, the major limitation of biomarkers is that it deals with the bio-molecular based …

A Multi-Channel 3d-Printed Bioreactor For Evaluation Of Growth And Production In The Microalga Dunaliella Sp, Cristian A. Cox

Electronic Theses and Dissertations

We explored the capabilities of additive manufacturing using a photo-cured jetted material 3D printer to manufacture a milli-microfluidic device with direct application in microalgae Dunaliella sp growth and intracellular compounds biosynthesis tests. A continuous microbioreactor for microalgae culture was CAD designed and successfully built in 1 hour and 49 minutes using black photopolymer cured by UV and a support material. The microreactor was made up of 2 parts including the bioreactor itself and a microchannel network for culture media fluids and microalgae. Both parts were assembled to form a single unit. Additional optical and auxiliar components were added. An external …

Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell

Electronic Theses and Dissertations

Photoelectrochemical water splitting has been identified as a promising route for achieving sustainable energy future. However, semiconductor materials with the appropriate optical, electrical and electrochemical properties have yet to be discovered. In search of an appropriate semiconductor to fill this gap, GaSbP, a semiconductor never tested for PEC performance is proposed here and investigated. Density functional theory (DFT+U) techniques were utilized to predict band gap and band edge energetics for GaSbP alloys with low amount of antimony. The overall objective of this dissertation is to understand the suitability of GaSb_xP_1-x alloys for photoelectrochemical water splitting application. Specifically, …

Fully Solution Processed Pedot:Pss And Silver Nanowire Semi-Transparent Electrodes For Thin Film Solar Cells, Bjorn Vaagensmith

Electronic Theses and Dissertations

Building integrated photovoltaics (BIPV), such as semitransparent organic solar cells (OSC) for power generating windows, is a promising method for implementing renewable energy under the looming threat of depleting fossil fuels. OSC require a solution processed transparent electrode to be cost effective; but typically employ a nonsolution processed indium tin oxide (ITO) transparent electrode. PEDOT:PSS and silver nanowire transparent electrodes have emerged as a promising alternative to ITO and are solution processed compatible. However, PEDOT:PSS requires a strong acid treatment, which is incompatible with high throughput solution processed fabrication techniques. Silver nanowires suffer from a short lifetime when subject to …

Urea Pre-Treatment Of N2-Annealed Transition Metal Oxides For Low Cost And Efficient Counter Electrodes In Dye-Sensitized Solar Cell, Hytham Elbohy

Electronic Theses and Dissertations

Photovoltaic cells have shown great promise as an alternative to fossil fuel-based energy sources. Dye-sensitized solar cells (DSSCs) have shown potential as low-cost replacement to silicon solar cells owing to their reduced material costs and simple fabrication techniques. Platinum (Pt) was used as a catalyst in the counter electrode for DSSCs. Metal oxides have been used as an alternative material to Pt. The introduction of oxygen vacancies inside metal oxides helps to facilitate electron transport to the electrolyte to enhance the reduction process of triiodide ions. Annealing n-type metal oxides under a reducing agent gas such as hydrogen (H2) at …

Integrated Tandem Dye Sensitized Solar Cell (Dssc)-Lithium Ion Battery, Geetha Varnekar

Electronic Theses and Dissertations

Efficient renewable energy harvesting and storage are needed for present challenges related to clean environment and increasing energy demand. Different types of energy harvesting technologies such as solar, thermal and wind require excess energy to be stored in batteries, which further adds to the complication and increase in cost to the overall renewable energy system. Integrating the generation and storage of solar energy in a single device would be a more cost effective way towards meeting the increasing energy demand due to its simplicity in design and less space consumptions. Herein, a sustainable photovoltaic cell integrated with an energy storage …

Synthesis And Characterization Of Kesterite Cu2znsns4 (Czts) Thin Films For Solar Cell Application, Mohamed M.A. Abusnina

Electronic Theses and Dissertations

The quaternary compound Cu₂ZnSnS₄ (CZTS) gained considerable attention in the last decade due to its potential as an active-layer semiconductor for low-cost thin-film solar cells. The material is composed of nontoxic and Earth-abundant constituents, has optical properties suitable for photovoltaic application, and can be synthesized using a wide variety of methods.

Polycrystalline CZTS was grown in this work using vacuum-based deposition to first deposit metal films (precursors) of Cu, Zn, and Sn. In a subsequent step, the precursors underwent an annealing treatment in sulfur vapor environment (sulfurization) to form CZTS. Using sputtering, a physical vapor deposition (PVD) …

Composite Gel Polymer Electrolyte For Lithium Ion Batteries, Roya Naderi

Electronic Theses and Dissertations

Batteries have been ubiquitously utilized in enormous applications such as portable electronics, satellites, computers, medical instruments, and electric cars. The development of battery technology has been through a long journey since the 17th century, paving its way to commercialization of lithium ion batteries in 1991 by Sony. Rechargeable lithium ion batteries represent the most favorable type of batteries for portable applications due to their high energy density compared to other alkali metals. In 1997, lithium polymer batteries with solid polymer/composite electrolyte were introduced where the safety drawbacks of the liquid electrolyte were eliminated but the ionic conductivity of the batteries …

Thermal And Structural Modeling Of Electrochromics On Glass, Mahesh B. Manandhar

Electronic Theses and Dissertations

Advanced glazing is a type of window glazing that interacts with the surrounding environment to change its thermal and optical properties to create a more comfortable and energy efficient indoor environment. Electrochromics are one type of such advanced glazing materials that change their properties in response to an externally applied voltage controllable by the user or by automation.

The effectiveness of electrochromics depends upon how well it can keep off extreme temperature conditions from outdoors all year round as well as how structurally stable it can remain at such conditions. This research investigates the use of COMSOL, a finite element …

New Open Source Software For Building Molecular Dynamics Systems, Bruce Michael Allen

Electronic Theses and Dissertations

The context of this work is the development of open source software to support researchers to quickly build systems of molecules for molecular dynamics (MD) simulations. The goal is achieved through the integration of three open source programs by judicious modifications and creation of new source code, which allows the creation of molecular models, MD cells and the LAMMPS geometry input files. The software changes work together supporting an easy and intuitive process for simulation system creation. Creation of multiple MD cells for research simulations becomes quicker and provides needed standardization to the simulation process. The researcher can select from …