Physical Sciences and Mathematics Commons^™

The Structure And Ferroelectric Properties Of Iron-Doped Lead Titanate, Michael Bartlein

Theses and Dissertations

Multiferroics are a class of poorly understood, but technologically important materials. Lead(II) titanate (PbTiO$_3$) is a known perovskite ferroelectric. By doping PbTiO$_3$ with Fe$^{3+}$ at the Ti site, we produce the multiferroic PbTi$_{1-x}$Fe$_x$O$_3$ (PTFO). Using selected area electron diffraction on a transmission electron microscope, the structure of PTFO is investigated. Of particular interest is identifying the cubic-to-tetragonal transition at the Curie temperature. As the concentration of Fe increases, the crystal becomes more cubic and experiences a lower transition temperature. I also establish a procedure for preparing bulk PTFO samples for ferroelectric testing and present preliminary results establishing ferroelectricity in these …

Evaluation And Forecast Of Energy Consumption In Different Sectors Of The United States Using Artificial Neural Networks, Arash Kialashaki

Theses and Dissertations

The United States is a country which consumes a vast amount of energy. In order to keep the development of the United States sustainable (diverse and productive over the time) energy planning should be carried out comprehensively and precisely. This dissertation presents a specific mathematical modeling approach towards energy demand modeling of the United States and forecast future energy demand. To generate more detailed and accurate results, this dissertation investigates the energy demand of each sector separately using the analysis of trend for unique set of independent parameters which affect the energy demand in that sector.

In solving a forecast …

Molecular Dynamics (Md) Study On The Electrochemical Properties Of Electrolytes In Lithium-Ion Battery (Lib) Applications, Negin Salami

Theses and Dissertations

While the high energy density and the power along with longer cycle life and less requirements of maintenance distinguish the rechargeable lithium-ion batteries (LIBs) from other energy storage devices, development of an electrolyte of LIBs with optimized properties still constitutes a challenge towards next-generation LIB systems with robust electrochemical performance. The electrolytes serve as the medium to provide ionic conduction path between the electrodes as their basic function. Conductivity of the solutions are mainly affected by their transport properties and the electrolyte electrode/separator interfacial phenomena. Although many contributions on thermodynamic properties of the electrolytes consist of alkyl carbonates mixed with …

A Decision Support System To Analyze, Predict, And Evaluate Solar Energy System Performance: Pvsysco (Photovoltaic System Comparison), Lisa Bosman

Theses and Dissertations

In 2010, the U.S. Department of Energy announced the SunShot Initiative, which aims to reduce the total installation cost of solar technologies by 75% between 2010 and 2020. This implies that solar energy is a top priority in the U.S. and many other countries. The purpose of this dissertation research is focused on creating a model to better understand the performance and reliability of photovoltaic (PV) energy systems over time. The model will be used to analyze, predict, and evaluate the performance of PV systems, taking into consideration technological and geographical location attributes. The overall research goal is to build …

Propagation Of An Optical Vortex In Fiber Arrays With Triangular Lattices, Muhammad Abdulrahman Mushref

Theses and Dissertations

The propagation of optical vortices (OVs) in linear and nonlinear media is an important field of research in science and engineering. The most important goal is to explore the properties of guiding dynamics for potential applications such as sensing, all-optical switching, frequency mixing and modulation. In this dissertation, we present analytical methods and numerical techniques to investigate the propagation of an optical vortex in fiber array waveguides. Analytically, we model wave propagation in a waveguide by coupled mode Equations as a simplified approximation. The beam propagation method (BPM) is also employed to numerically solve the paraxial wave Equation by finite …

Assessing Survivability Of The Beijing Subway System, Yan Li, Hyun Kim

International Journal of Geospatial and Environmental Research

The Beijing subway system, the third largest in the world, serves more than ten million passengers a day. As Beijing is the capital city of China and thus a booming urban center, its subway system has experienced rapid evolution from a local single line system to a complicated network. Due to its constantly increasing complexity, the system is both a critical asset for a local transit artery and a bridge between intercity transportation modes, increasing the issue of network survivability in the face of potential outages of network components. In this study, we provide a connectivity-based survivability measure with which …

Impacts Of Remotely Sensed Land Use Data On Watershed Hydrologic Change Assessment, Gi-Choul Ahn, Steven I. Gordon, Carolyn J. Merry

International Journal of Geospatial and Environmental Research

Urbanization affects the stream system of a watershed. Increased urbanization alters the land cover and surface characteristics, the stream channel characteristics, and pollutant load of a stream system by increasing the amount of impervious surface. Once rural, forest, or wetland areas are changed to streets, highways, parking lots, sidewalks, and building rooftops. This results in large volumes of runoff being generated for an intense storm over a relatively short time period. As a result, sensitive ecosystems are likely to be damaged by increased urbanization.

Projecting the impact of land use changes on a watershed scale often requires the use of …

Wetting, Superhydrophobicity, And Icephobicity In Biomimetic Composite Materials, Vahid Hejazi

Theses and Dissertations

Recent developments in nano- and bio-technology require new materials. Among these new classes of materials which have emerged in the recent years are biomimetic materials, which mimic structure and properties of materials found in living nature. There are a large number of biological objects including bacteria, animals and plants with properties of interest for engineers. Among these properties is the ability of the lotus leaf and other natural materials to repel water, which has inspired researchers to prepare similar surfaces. The Lotus effect involving roughness-induced superhydrophobicity is a way to design nonwetting, self-cleaning, omniphobic, icephobic, and antifouling surfaces. The range …

Design Of A Micro-Focus X-Ray Source Validated By Model Protein Crystals, Lavanya Ramachandran

Theses and Dissertations

The main objective of this thesis was to build a Laboratory Microfocus X-ray Source for Protein Crystallography (LMXS-PC), an X-ray source that would provide prospective users programmatic control and remote capability.

A study of the crystal was conducted using Photoactive Yellow protein (PYP) and cytochrome c nitrite reductase (ccNiR). The instrument was then tested by mounting the crystal in the instrument and collecting data.

The other objective of my research work was to determine the crystal structure of PYP using X-ray crystallography techniques. I attempted many trials in PYP crystal in an effort to achieve a high-quality diffraction pattern; however, …

Monitoring Changes In Hemodynamics Following Optogenetic Stimulation, Seth Thomas Frye

Theses and Dissertations

The brain is composed of billions of neurons, all of which connected through a vast network. After years of study and applications of different technologies and techniques, there are still more questions than answers when it comes to the fundamental functions of the brain. This project aims to provide a new tool which can be used to gain a better understanding of the fundamental mechanisms that govern neurological processes inside the brain. In order for neural networks to operate, blood has to be supplied through neighboring blood vessels. As such, the increase or decrease in the blood supply has been …

The Occurrence, Fate, Environmental Impact, And Management Implications Of Pharmaceutical And Personal Care Products In Wastewater And The Environment, Benjamin Donald Blair

Theses and Dissertations

Pharmaceuticals and personal care products (PPCPs) are a critical part of modern life. However, there is growing evidence that the levels of PPCPs detected in wastewater effluent and in the environment have the potential to cause damage to aquatic organisms. These pollutants enter the aquatic environment primarily through human use, disposal in the drain or toilet, land application of biosolids, and veterinary sources. Numerous questions remain regarding the occurrence, fate, and impacts of PPCPs in wastewater, along with limited feasible management recommendations that would adequately mitigate the risk from these pollutants. This dissertation will present three advances in the field …

Citefinder: A System To Find And Rank Medical Citations, Seyed Soheil Moosavinasab

Theses and Dissertations

This thesis presents CiteFinder, a system to find relevant citations for clinicians' written content. Inclusion of citations for clinical information content makes the content more reliable through the provision of scientific articles as references, and enables clinicians to easily update their written content using new information. The proposed approach splits the content into sentences, identifies the sentences that need to be supported with citations by applying classification algorithms, and uses information retrieval and ranking techniques to extract and rank relevant citations from MEDLINE for any given sentence. Additionally, this system extracts snippets from the retrieved articles. We assessed our approach …

Nonlinear Processes In Multi-Mode Optical Fibers, Hamed Pourbeyram Kaleibar

Theses and Dissertations

Nonlinear processes in optical fibers can affect data transmission and power carried by

optical fibers and can limit the bandwidth and the capacity of optical communications.

On the other hand nonlinear phenomena could be utilized to build in-fiber all-optical

light sources and amplifiers. In this thesis new peaks inside an optical fiber have been

generated using nonlinear processes. An intense green pump laser has been launched

into a short fiber and specific modes have been excited to generate two new peaks in

red and blue wavelengths, where two pump photons are annihilated to create two new

photons in red and …