Physical Sciences and Mathematics Commons^™

Transits Of Non-Spherical Exoplanets, Bertrand Carado

Legacy Theses & Dissertations (2009 - 2024)

The recent years have shed light on amazing new worlds across the galaxy. It has been demonstrated that the Solar System is only one of many other systems. The Kepler Space Observatory, which was launched by NASA in 2009, has greatly contributed to expand knowledge of exoplanets whose characteristics (how massive they are, their size, orbital period, temperature...) vary on a surprisingly large scale. As an example, the least massive exoplanet known today has twice the mass of the moon [1]. The most massive exoplanet has 29 times the mass of Jupiter [2]. Orbital periods of known planets vary between …

Illumination Modulation For Improved Propagation-Based Phase Imaging, Tonmoy Chakraborty

Legacy Theses & Dissertations (2009 - 2024)

Propagation-based phase imaging enables the quantitative reconstruction of a light beam's phase from measurements of its intensity. Because the intensity depends on the time-averaged square of the field the relationship between intensity and phase is, in general, nonlinear. The transport of intensity equation (TIE), is a linear equation relating phase and propagated intensity that arises from restricting the propagation distance to be small. However, the TIE limits the spatial frequencies that can be reliably reconstructed to those below some cutoff, which limits the accuracy of reconstruction of fine features in phase. On the other hand, the low frequency components suffer …

The Entropic Dynamics Approach To The Paradigmatic Quantum Mechanical Phenomena, Susan Difranzo

Legacy Theses & Dissertations (2009 - 2024)

Standard Quantum Mechanics, although successful in terms of calculating and predicting

Radiation Effects In Tantalum Oxide-Based Resistive Memory Devices, Joshua Stuart Holt

Legacy Theses & Dissertations (2009 - 2024)

There is an increasing need for radiation-hardened electronics as space programs grow in number and scope. Scientific interest in long-term exploration, particularly in high-radiation environments such as Europa, as well as commercial interest in establishing permanent outposts, requires high tolerance of radiation effects. A flash memory device might survive for several years in low Earth orbit, but only a few days in orbit around Europa due to the extremely high levels of radiation encountered there. Meanwhile, commercial interests, including asteroid mining and building a base on the moon or Mars would require electronic systems that could survive for long periods …

Mesh And Diffraction-Based X-Ray Phase Imaging, Congxiao He

Legacy Theses & Dissertations (2009 - 2024)

More than a hundred years have passed since X-rays were detected by Wilhelm Rontgen. Due to their properties, they soon became widely applied in many areas, especially medical imaging. Recently, many new X-ray imaging techniques were designed, including phase imaging and diffraction enhanced imaging, DEI.

Effects Of Interface Scattering And Carrier Localization On Conductance Of Cu-Based Superlattices, Jiyoon Jessica Kim

Legacy Theses & Dissertations (2009 - 2024)

Ultra-thin films and multilayer structures are widely used in modern technologies such as semiconductor logic and memory devices. As film thickness decreases to a few nanometers or smaller, classical transport theories are no longer valid. In this study, we investigate transport properties of superlattices with layer thickness reduced to ~1 nm. The superlattices are made of alternating layers of Cu and a transition metal (Ru, Mo, and Co). The layers are deposited by physical vapor deposition and resistance changes during superlattice growth are measured. The observed resistance evolution reveals the effects of carrier scattering and localization at the interfaces.

The N=1 Singlet Vertex Superalgebra Sm(1), Scott Richey Sidoli

Legacy Theses & Dissertations (2009 - 2024)

In this work we study the vertex operator superalgebra known as the singlet vertex operator superalgebra, denoted $\overline{SM(1)}$. We are particularly interested in the number theoretic properties of the characters, and supercharacters, of irreducible modules of $\overline{SM(1)}$ as modules over the Neveu-Schwarz and Ramond Lie superalgebras, denoted $\mathfrak{ns}$ and $\mathfrak{R}$, respectively. These characters occur as modular-like forms, namely false and mock theta functions. The $S$- and $T$- transformations are computed and we demonstrate modular invariance of the vector space spanned by these characters and supercharacters. We use a continuous version of the Verlinde formula, introduced by Creutzig and Milas, to …

The Inferential Design Of Entropy And Its Application To Quantum Measurements, Kevin Vanslette

Legacy Theses & Dissertations (2009 - 2024)

This thesis synthesizes probability and entropic inference with Quantum Mechanics and quantum measurement [1-6]. It is shown that the standard and quantum relative entropies are tools \emph{designed} for the purpose of updating probability distributions and density matrices, respectively [1]. The derivation of the standard and quantum relative entropy are completed in tandem following the same inferential principles and design criteria. This provides the first design derivation of the quantum relative entropy while also reducing the number of required design criteria to two.

Carrier Scattering And Localization In Nm-Thick Al/Ru, Al/Co And Al/Mo Superlattices, Yanli Zhang

Legacy Theses & Dissertations (2009 - 2024)

Thin films and superlattices are widely used in modern technologies. Certain metal superlattices with layer thickness between 1 to 10 nm have interesting magneto transport properties and unique applications in spintronics and data storage. We have studied electrical conductance of Al/Ru, Al/Co, and Al/Mo superlattices with layer thickness between 1 to 2 nm. By monitoring the resistance change during the growth of the superlattice, we are able to observe directly the effects of carrier localization and scattering when a highly disordered interface is being deposited.

The Classical Limit Of Entropic Quantum Dynamics, Anthony V. Demme

Physics

The framework of entropic dynamics (ED) allows one to derive quantum mechanics as an application of entropic inference. In this work we derive the classical limit of quantum mechanics in the context of ED. Our goal is to find conditions so that the center of mass (CM) of a system of N particles behaves as a classical particle. What is of interest is that ~ remains finite at all steps in the calculation and that the classical motion is obtained as the result of a central limit theorem. More explicitly we show that if the system is sufficiently large, and …

Influence Of Volcanic Eruptions On Tropical Hydroclimate During The Last Millennium, Christopher Colose

Legacy Theses & Dissertations (2009 - 2024)

Volcanic eruptions exert the most important radiative forcing on Earth’s climate during the pre-industrial interval of the last millennium. In this thesis, I investigate the role of volcanic eruptions in altering tropical climate, including temperature and rainfall. I primarily use forced transient simulations of the last millennium as a tool to explore how explosive volcanic events project onto the hydrologic cycle, as well as the imprint of water isotopologues (H216O, H218O) associated with rainfall. Attention is given to the South American continent specifically (in chapter 2), and to the entire tropics (in chapter 3).

Hidden Symmetries In String Theory, Iurii Chervonyi

Legacy Theses & Dissertations (2009 - 2024)

In this thesis we study hidden symmetries within the framework of string theory. Symmetries play a very important role in physics: they lead to drastic simplifications, which allow one to compute various physical quantities without relying on perturbative techniques.

A Three-Body Simulation Of Kepler-91 : A Potential Trojan System, Bryan Daniel D'Angelo

Legacy Theses & Dissertations (2009 - 2024)

This paper presents a three-body simulation of Kepler-91 (KIC 8219268) using parameters

Mesh-Based Fourier Imaging For Biological And Security Applications, Danielle Justine Hayden

Legacy Theses & Dissertations (2009 - 2024)

Traditional x-ray imaging provides only low contrast from low atomic number materials, like soft tissue, due to the small attenuation variations producing very small intensity changes. Higher contrast can be achieved through phase information. The phase change is obtained from the x-ray refracting in a sample, or phase object, due to the difference in refractive indexes. This causes a small angular deviation from the original path. Phase contrast imaging has not been realized in everyday practice due to the requirement for large spatial coherence width of the x-ray beam which typically requires sources on the order of 10-50 m, the …

Materials For Giant Spin Hall Effect Devices, Avyaya Jayanthinarasimham

Legacy Theses & Dissertations (2009 - 2024)

Studies presented in this thesis are an effort to control the growth of β W and explore

Exploring Magnetic Nanostructures Embedded Within Single-Crystal Silicon For Generation Of Spin-Polarized Carriers, Machara Krishna Girish Malladi

Legacy Theses & Dissertations (2009 - 2024)

Integrating magnetic functionalities with silicon holds the promise of developing, in the most dominant semiconductor, a paradigm-shift information technology based on the manipulation and control of electron spin and charge. Here, we demonstrate an ion implantation approach enabling the synthesis of a ferromagnetic layer within a defect free Si environment by exploiting an additional implant of hydrogen in a region deep below the metal implanted layer. Upon post-implantation annealing, nanocavities created within the H-implanted region act as trapping sites for gettering the implanted metal species, resulting in the formation of metal nanoparticles in a Si region of excellent crystal quality. …

Mechanisms Of Euv Exposure : Photons, Electrons And Holes, Amrit Kausik Narasimhan

Legacy Theses & Dissertations (2009 - 2024)

The microelectronics industry’s movement toward smaller and smaller feature sizes has necessitated a shift to Extreme Ultra-Violet (EUV) lithography to be able to pattern sub 20-nm features, much like earlier shifts from i-line to 248 nm. However, this shift from 193-nm lithography to EUV (13.5 nm) poses significant obstacles. EUV is the first optical lithography to operate in an energy range (92 eV per photon vs. 6.4 eV per photon for 193 nm lithography) above the electron binding energies of common resist atomic species. This significant energy increase complicates resist design. For exposures of equal dose, resists receive 14 times …

Coherent Scatter And Grid-Based Phase Imaging For Materials Discrimination, Sean Niccholas Starr-Baier

Legacy Theses & Dissertations (2009 - 2024)

Traditional X-Ray images provide a meaningful way to differentiate between materials with differing attenuation coefficients. The low contrast provided by this method for materials of low electron density or similar attenuation is a limitation of traditional radiography. Two alternatives have presented themselves as viable candidates for widening the viability of X-Ray imaging, Coherent scatter, and phase contrast imaging provide a means to distinguish between objects of both low absorption and similar attenuation.

Characterizing Kepler Objects Of Interest Using The Algorithm Exonest, Bertrand Carado

Physics

Recent observations across the galaxy have led to the conclusion that there exist many different extrasolar systems. Using photometric effects, the amount of data that has been produced on exoplanets has significantly increased and will continue to rise. Finding new methods of data analysis to broaden the spectrum of research has therefore become a necessity. Exonest is an algorithm currently in development that uses Bayesian methods, and notably nested sampling, to infer characteristics about an exoplanet from its observed light curve.

In this paper, Exonest was tested by being used to study three extra-solar systems: each containing a single confirmed …

The Utilization Of Exonest In Characterizing Kepler Objects, Nicole Wallack

Physics

With the first detection of an exoplanet, came the study of methods to detect and characterize additional planets. Multiple methods for finding exoplanets were developed, including transit methods. When a star’s flux is being observed for an extended period of time and a slight dip in the relative flux is seen periodically, this may be evidence of a planet passing in front of the star and blocking out a portion of the received flux. It is this method that is employed by the Kepler spacecraft. Kepler observes approximately 100,000 stars looking for periodic decreases in stellar fluxes. From the produced …

Bayesian Model Testing Of Models For Ellipsoidal Variation On Stars Due To Hot Jupiters, Anthony Gai

Legacy Theses & Dissertations (2009 - 2024)

A massive planet closely orbiting its host star creates tidal forces that distort the typically spherical stellar surface. These distortions, known as ellipsoidal variations, result in variations in the photometric flux emitted by the star, which can be detected by the Kepler Space Telescope. Currently, there exist several models describing such variations and their effect on the photometric fux [1] [2] [3] [4]. By using Bayesian model testing in conjunction with the Bayesian-based exoplanet characterization software package EXONEST [4] [5] [6], the most probable representation for ellipsoidal variations was determined for synthetic data and two systems with confirmed hot Jupiter …

Development Of Iii-Sb Based Technologies For P-Channel Mosfet In Cmos Applications, Shailesh Kumar Madisetti

Legacy Theses & Dissertations (2009 - 2024)

The continuous scaling of silicon CMOS predicts the end of roadmap due to the difficulties such as that arise from electrostatic integrity, design complexities, and power dissipation. These fundamental and practical limitations bring the need for innovative design architectures or alternate materials with higher carrier transport than current Si based materials. New device designs such as multigate/gate-all-around architectures improve electrostatics while alternate materials like III-Vs such as III-As for electrons and III-Sbs for holes increase operational speed, lower power dissipation and thereby improve performance of the transistors due to their low effective mass and faster transport properties. Further, application of …

Magnetoresistance Of A Low-K Dielectric, Brian Thomas Mcgowan

Legacy Theses & Dissertations (2009 - 2024)

Low-k dielectrics have been incorporated into advanced computer chip technologies as a part of the continuous effort to improve computer chip performance. One drawback associated with the implementation of low-k dielectrics is the large leakage current which conducts through the material, relative to silica. Another drawback is that the breakdown voltage of low-k dielectrics is low, relative to silica [1]. This low breakdown voltage makes accurate reliability assessment of the failure mode time dependent dielectric breakdown (TDDB) in low-k dielectrics critical for the successful implementation of these materials. The accuracy with which one can assess this reliability is currently a …

Bayesian Signal Detection And Source Separation In Simulated Brain Computer Interface Systems, Muhammad Asim Mubeen

Legacy Theses & Dissertations (2009 - 2024)

The problems of signal detection and source separation are important in many fields of science and engineering. In many cases, a target signal needs to be detected in real time and is contaminated by noise. Sometimes the level of noise is on the order of the signal itself. The real time detection of a target signal is of key importance in problems such as the brain computer interface systems. In brain computer interface systems, the neural activity (electric signals) of the brain is detected using sensors (electrodes) on the surface of the brain or the scalp. This signal is contaminated …

The Detection And Characterization Of Extrasolar Planets, Zachary Richards

Legacy Theses & Dissertations (2009 - 2024)

The study of extra-solar planets (exoplanets) is a rapidly expanding field, which aims to detect, characterize, and understand how other planetary systems form and behave. Observing an exoplanet transit its host star allows us to detect the exoplanet in the light curve. As an exoplanet transits, there will be a dip in the total flux (light per unit area) of the host star visible in the light curve. While observing an exoplanet transit, several photometric effects may influence the light curve. We consider the following photometric effects: reflected light, Doppler boosting (beaming), thermal emission, and ellipsoidal variation. This study relies …

Novel Two-Dimensional Devices For Future Applications, Pratik Agnihotri

Legacy Theses & Dissertations (2009 - 2024)

The scalability of field effect transistor has led to the monumental success of complementary metal-oxide-semiconductor (CMOS) technology. In the past, device scaling was not the major issue to a greater extent. Recently with current technology nodes, transistor characteristics show signs of reduced performance due to short channel effects and other issues related to device scaling. Device designers look for innovative ways to enhance the transistor performance while keeping up with device miniaturization. Successful inventions include the development of tri-gate technology, gate all around (GAA) field effect transistors, silicon-on-insulator substrate, and high-k dielectrics. These developments have enabled the device scaling that …

Tailoring The Optical Properties Of Silicon With Ion Beam Created Nanostructures For Advanced Photonics Applications, Perveen Akhter

Legacy Theses & Dissertations (2009 - 2024)

In today’s fast life, energy consumption has increased more than ever and with that the demand for a renewable and cleaner energy source as a substitute for the fossil fuels has also increased. Solar radiations are the ultimate source of energy but harvesting this energy in a cost effective way is a challenging task. Si is the dominating material for microelectronics and photovoltaics. But owing to its indirect band gap, Si is an inefficient light absorber, thus requiring a thickness of solar cells beyond tens of microns which increases the cost of solar energy. Therefore, techniques to increase light absorption …

A Tale Of Two Searches With The Atlas Detector At The Large Hadron Collider, Julian Bouffard

Legacy Theses & Dissertations (2009 - 2024)

Two searches carried out with the ATLAS detector at the Large Hardron Collider at a center of mass energy of 8 TeV. Primarily, a search for the associated production of a Standard Model Higgs boson produced in association with a top quark pair. Additionally, a search for the existence of R-Parity violating Supersymmetry.

Thermal Transportability Based Gas Analysis Using Fiber Bragg Grating Sensors, Yuan Chang

Legacy Theses & Dissertations (2009 - 2024)

Compositional analysis of gases in real time is important for many industries. Traditionally, it was done with online sensors such as thermal conductivity detectors or analytical methods such as gas chromatography. Fiber Bragg grating (FBG) sensors have demonstrated unique advantages in gas sensing. This dissertation focuses on the designing of a thermal modulation system that can properly functionalize FBG sensors, and the building of a sensing system that can perform non-specific gas compositional analysis in real time for pure gases and binary gas mixtures.

The Van Der Pol Oscillator As A Model Of The Hair Cell Auditory Response: A Numerical Study, Thomas Yocono

Physics

Hair cells, which detect and encode sound stimuli, have been shown to have a non-linear response and self sustaining oscillations. Here, we look at the Van der Pol oscillator, which has these properties, and numerically calculate its response to multiple driving frequencies. Any nonlinear system's response to multiple driving frequencies will have not just the driving frequencies present, but also combination tones, or heterodyne frequencies, which have order defined by the number of driving frequency combinations. This phenomenon has been experimentally confirmed in the human auditory response [1]. In the frequency specture of the Van der Pol steady state response …