Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Electronic Theses and Dissertations

Discipline
Institution
Keyword
Publication Year
File Type

Articles 1561 - 1590 of 4195

Full-Text Articles in Physical Sciences and Mathematics

Quasi-Gorenstein Modules, Alexander York Jan 2018

Quasi-Gorenstein Modules, Alexander York

Electronic Theses and Dissertations

This thesis will study the various roles that quasi-Gorenstein modules and their properties play in the study of homological dimensions and linkage of modules. To that effect we begin by studying these modules in their own right. An R-module M of grade g will be quasi-Gorenstein if ExtiR(M, R) = 0 for i 6= g and there is an isomorphism M ∼= ExtgR(M, R). Such modules have many nice properties which we will explore throughout this thesis. We will show they help extend a characterization of diagonalizable matrices over principal ideal domains to more general rings. We will use their …

Go to article

In-Memory Computing Using Formal Methods And Paths-Based Logic, Alvaro Velasquez Jan 2018

In-Memory Computing Using Formal Methods And Paths-Based Logic, Alvaro Velasquez

Electronic Theses and Dissertations

The continued scaling of the CMOS device has been largely responsible for the increase in computational power and consequent technological progress over the last few decades. However, the end of Dennard scaling has interrupted this era of sustained exponential growth in computing performance. Indeed, we are quickly reaching an impasse in the form of limitations in the lithographic processes used to fabricate CMOS processes and, even more dire, we are beginning to face fundamental physical phenomena, such as quantum tunneling, that are pervasive at the nanometer scale. Such phenomena manifests itself in prohibitively high leakage currents and process variations, leading …

Go to article

Terahertz Emission From The Intrinsic Josephson Junctions Of High-Symmetry Thermally-Managed Bi2sr2cacu2o8+D Annular Microstrip Antennas, Sheila Bonnough Jan 2018

Terahertz Emission From The Intrinsic Josephson Junctions Of High-Symmetry Thermally-Managed Bi2sr2cacu2o8+D Annular Microstrip Antennas, Sheila Bonnough

Electronic Theses and Dissertations

The intrinsic Josephson junctions in the high transition temperature superconductor Bi2Sr2CaCu2O8+δ (BSCCO) have shown great potential for oscillators emitting in the terahertz frequency. The radiation frequency satisfies the conditions for both the ac Josephson effect and for a mesa cavity resonance mode. The observed angular dependence of the emissions from some mesa imply that the ac Josephson effect plays the primary role in a dual source radiation mechanism. But the integrated emission power had generally been significantly below the 1 mW level suitable for many applications. This output power can be enhanced by a suitable design of an array of …

Go to article

Weierstrass Vertices And Divisor Theory Of Graphs, Ajani Ruwandhika Chulangi De Vas Gunasekara Jan 2018

Weierstrass Vertices And Divisor Theory Of Graphs, Ajani Ruwandhika Chulangi De Vas Gunasekara

Electronic Theses and Dissertations

Chip-firing games and divisor theory on finite, connected, undirected and unweighted graphs have been studied as analogs of divisor theory on Riemann Surfaces. As part of this theory, a version of the one-dimensional Riemann-Roch theorem was introduced for graphs by Matt Baker in 2007. Properties of algebraic curves that have been studied can be applied to study graphs by means of the divisor theory of graphs. In this research, we investigate the property of a vertex of a graph having the Weierstrass property in analogy to the theory of Weierstrass points on algebraic curves. The weight of the Weierstrass vertices …

Go to article

Undergraduate Student Agreement With Reformed Introductory Physics Classes, Matthew Wilcox Jan 2018

Undergraduate Student Agreement With Reformed Introductory Physics Classes, Matthew Wilcox

Electronic Theses and Dissertations

In this study, I investigate student "buy-in", defined as students' proper understanding of and agreement with the class format, for introductory studio physics classes that incorporate lectures, labs, and group problem-solving activities into one interactive environment. I also investigate the ways in which instructors try to gain student buy-in to their class. Research has shown that student resistance to reformed instruction is a barrier to an instructor's use of research-based instructional strategies that are common to the studio class. Expectancy value theory suggests that by gaining student buy-in to the reformed class format, student resistance will decrease thus allowing a …

Go to article

Assessment Of Information Security Culture In Higher Education, Henry Glaspie Jan 2018

Assessment Of Information Security Culture In Higher Education, Henry Glaspie

Electronic Theses and Dissertations

Information security programs are instituted by organizations to provide guidance to their users who handle their data and systems. The main goal of these programs is to protect the organization's information assets through the creation and cultivation of a positive information security culture within the organization. As the collection and use of data expands in all economic sectors, the threat of data breach due to human error increases. Employee's behavior towards information security is influenced by the organizations information security programs and the overall information security culture. This study examines the human factors of an information security program and their …

Go to article

Hilbert Series Of Graphs, Hypergraphs, And Monomial Ideals, Kyle Trainor Jan 2018

Hilbert Series Of Graphs, Hypergraphs, And Monomial Ideals, Kyle Trainor

Electronic Theses and Dissertations

In this dissertation, identities for Hilbert series of quotients of polynomial rings by monomial ideals are explored, beginning in the contexts of graph and hypergraph rings and later generalizing to general monomial ideals. These identities are modeled after constructive identities from graph theory, and can thus be used to construct Hilbert series iteratively from those of smaller algebraic structures.

Go to article

Power Scaling Of High Power Solid State Lasers., Bumjin Oh Jan 2018

Power Scaling Of High Power Solid State Lasers., Bumjin Oh

Electronic Theses and Dissertations

The solid-state laser is one of the most widely used lasers in scientific research and industrial applications. This thesis describes detailed investigations of two modern architectures of high power cw solid-state lasers, a 20 W diode-pumped Yb:YAG thin disc laser and 300 W diode-pumped Nd:YAG rod laser. With the thin disc laser architecture, the signal beam must fit to the pump area on the disc defined by the multi-pass diode pump configuration. The beam propagation, beam diameter, phase and thermal effects for various cavity configurations are investigated theoretically and experimentally. In addition, the internal loss, small signal gain, and thermal …

Go to article

From Excited Charge Dynamics To Cluster Diffusion: Development And Application Of Techniques Beyond Dft And Kmc, Shree Ram Acharya Jan 2018

From Excited Charge Dynamics To Cluster Diffusion: Development And Application Of Techniques Beyond Dft And Kmc, Shree Ram Acharya

Electronic Theses and Dissertations

This dissertation focuses on developing reliable and accurate computational techniques which enable the examination of static and dynamic properties of various activated phenomena using deterministic and stochastic approaches. To explore ultrafast electron dynamics in materials with strong electron-electron correlation, under the influence of a laser pulse, an ab initio electronic structure method based on time-dependent density functional theory (TDDFT) in combination with dynamical mean field theory (DMFT) is developed and applied to: 1) single-band Hubbard model; 2) multi-band metal Ni; and 3) multi-band insulator MnO. The ultrafast demagnetization in Ni reveal the importance of memory and correlation effects, leading to …

Go to article

Investigating Compositional Variations Of S-Complex Near-Earth Asteroids: (1627) Ivar, Jenna Jones Jan 2018

Investigating Compositional Variations Of S-Complex Near-Earth Asteroids: (1627) Ivar, Jenna Jones

Electronic Theses and Dissertations

We seek to investigate the complexity and heterogeneity of the surfaces of near-Earth asteroids (NEAs). In particular, we are studying the S-complex NEAs, which account for a large portion of the observed near-Earth objects. Here we present our results for (1627) Ivar, an Amor class NEA with taxonomic type Sqw. In 2013, Ivar's large size and close approach to Earth (minimum distance 0.32 AU) provided an opportunity to observe the asteroid over many different viewing angles for an extended period of time. We collected delay-Doppler radar images and Doppler spectra using the Arecibo Observatory's 2380 MHz radar, and, by incorporating …

Go to article

Electronic, Optical, And Magnetic Properties Of Graphene And Single-Layer Transition Metal Dichalcogenides In The Presence Of Defects, Mahtab Khan Jan 2018

Electronic, Optical, And Magnetic Properties Of Graphene And Single-Layer Transition Metal Dichalcogenides In The Presence Of Defects, Mahtab Khan

Electronic Theses and Dissertations

Two-dimensional (2D) materials, such as graphene and single-layer (SL) transition metal dichalcogenides (TMDCs), have attracted a lot of attention due to their fascinating electronic and optical properties. Graphene was the first 2D material that has successfully been exfoliated from bulk graphite in 2004. In graphene, charge carriers interacting with the honeycomb lattice of carbon atoms of graphene to appear as massless Dirac fermions. Massless quasiparticles with linear dispersion are also observed in surface states of 3D topological insulators and quantum Hall edge states. My first project deals with the two-dimensional Hong-Ou-Mandel (HOM) type interference experiment for massless Dirac fermions in …

Go to article

Polyelectrolyte Complexes Based On Poly(Acrylic Acid): Mechanics And Applications, Xiaoyan Lu Jan 2018

Polyelectrolyte Complexes Based On Poly(Acrylic Acid): Mechanics And Applications, Xiaoyan Lu

Electronic Theses and Dissertations

Poly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic condition when the carboxylic group loses a proton. These carboxylate group can interact with polycations and metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable properties and multifunctional nanoscale structures through chemical reactions. This research focuses on nanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferric ion concentration on the mechanical properties of PAA-based single naonofiber by using dark field microscopy imaging and persistence length analysis. The application of PAA-based nanofiber mats loaded with MnO2 for supercapacitors was also explored. As a …

Go to article

Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li Jan 2018

Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li

Electronic Theses and Dissertations

The observation of any atomic and molecular dynamics requires a probe that has a timescale comparable to the dynamics itself. Ever since the invention of laser, the temporal duration of the laser pulse has been incrementally reduced from several nanoseconds to just attoseconds. Picosecond and femtosecond laser pulses have been widely used to study molecular rotation and vibration. In 2001, the first single isolated attosecond pulse (1 attosecond = 10^-18 seconds.) was demonstrated. Since this breakthrough, "attoscience" has become a hot topic in ultrafast physics. Attosecond pulses typically have span between EUV to X-ray photon energies and sub-femtosecond pulse duration. …

Go to article

Integration Of Fundamental Research And Cer: The Role Of Authenticity In Developing Views On The Nature Of Teaching, Learning, And Doing Science, Julie Donnelly Jan 2018

Integration Of Fundamental Research And Cer: The Role Of Authenticity In Developing Views On The Nature Of Teaching, Learning, And Doing Science, Julie Donnelly

Electronic Theses and Dissertations

This dissertation is an integration of fundamental research and chemical education. It begins with two nonlinear spectroscopic studies of compounds important to the study of brain chemistry. In Chapter 2, we present a novel method using quantum mechanics for modelling ligand docking and the potential of nonlinear circular dichroism for elucidating the mechanism of cannabinoids docking to their receptor, a contribution to studies of varying psychological effects of cannabinoids. Considering existent challenges with measuring this phenomenon, in Chapter 3, we evaluate two-photon absorption properties of Thioflavin T (ThT) in varying glycerol/water content solutions and discuss the enhancement of nonlinear absorption …

Go to article

2 Micron Fiber Lasers: Power Scaling Concepts And Limitations, Alex Sincore Jan 2018

2 Micron Fiber Lasers: Power Scaling Concepts And Limitations, Alex Sincore

Electronic Theses and Dissertations

Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses …

Go to article

Single Mode Wavelength-Tunable Thulium Fiber, Dong Jin Shin Jan 2018

Single Mode Wavelength-Tunable Thulium Fiber, Dong Jin Shin

Electronic Theses and Dissertations

Thulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75μm and ends at around 2.15μm, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them uniquely suited for applications such as remote sensing. At the moment, high power beam propagation of continuous wave laser through the atmosphere in the mid-infrared range is yet to …

Go to article

Cavity-Coupled Plasmonic Systems For Enhanced Light-Matter Interactions, Abraham Vazquez-Guardado Jan 2018

Cavity-Coupled Plasmonic Systems For Enhanced Light-Matter Interactions, Abraham Vazquez-Guardado

Electronic Theses and Dissertations

Light-matter interaction is a pivotal effect that involves the synergetic interplay of electromag- netic fields with fundamental particles. In this regard localized surface plasmons (LSP) arise from coherent interaction of the electromagnetic field with the collective oscillation of free electrons in confined sub-wavelength environments. Their most attractive properties are strong field en- hancements at the near field, highly inhomogeneous, peculiar temporal and spatial distributions and unique polarization properties. LSP systems also offer a unique playground for fundamental electromagnetic physics where micro-scale systemic properties can be studied in the macro-scale. These important properties and opportunities are brought up in this work …

Go to article

Liquid Crystal Phase Modulation For Beam Steering And Near-Eye Displays, Yun-Han Lee Jan 2018

Liquid Crystal Phase Modulation For Beam Steering And Near-Eye Displays, Yun-Han Lee

Electronic Theses and Dissertations

Liquid crystal spatial phase modulator plays an important role in laser beam steering, wave-front shaping and correction, optical communication, optical computation and holography. One fundamental limitation lays in the response time of liquid crystal reorientation. To achieve fast response time, polymer-network liquid crystals are therefore proposed. By incorporating polymer network in a liquid crystal host, the response time can be reduced by a factor of 100. However, the polymer network introduces hysteresis, light scattering, and high voltage. The motivation for a fast-response liquid crystal phase modulator will be discussed in the first chapter. In the second chapter, we introduce our …

Go to article

Relating First-Person And Third-Person Vision, Shervin Ardeshir Behrostaghi Jan 2018

Relating First-Person And Third-Person Vision, Shervin Ardeshir Behrostaghi

Electronic Theses and Dissertations

Thanks to the availability and increasing popularity of wearable devices such as GoPro cameras, smart phones and glasses, we have access to a plethora of videos captured from the first person (egocentric) perspective. Capturing the world from the perspective of one's self, egocentric videos bear characteristics distinct from the more traditional third-person (exocentric) videos. In many computer vision tasks (e.g. identification, action recognition, face recognition, pose estimation, etc.), the human actors are the main focus. Hence, detecting, localizing, and recognizing the human actor is often incorporated as a vital component. In an egocentric video however, the person behind the camera …

Go to article

Examining Users' Application Permissions On Android Mobile Devices, Muhammad Safi Jan 2018

Examining Users' Application Permissions On Android Mobile Devices, Muhammad Safi

Electronic Theses and Dissertations

Mobile devices have become one of the most important computing platforms. The platform's portability and highly customized nature raises several privacy concerns. Therefore, understanding and predicting user privacy behavior has become very important if one is to design software which respects the privacy concerns of users. Various studies have been carried out to quantify user perceptions and concerns [23,36] and user characteristics which may predict privacy behavior [21,22,25]. Even though significant research exists regarding factors which affect user privacy behavior, there is gap in the literature when it comes to correlating these factors to objectively collected data from user devices. …

Go to article

Far-Infrared Bands In Plasmonic Metal-Insulator-Metal Absorbers Optimized For Long Wave Infrared, Rachel Evans Jan 2018

Far-Infrared Bands In Plasmonic Metal-Insulator-Metal Absorbers Optimized For Long Wave Infrared, Rachel Evans

Electronic Theses and Dissertations

Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a thin dielectric, and thin separated metal top-surface structures. Long-wave infrared (LWIR) fundamental absorptions are experimentally shown to be optimized for a ratio of dielectric thickness to top-structure dimension t/l > 0.08. The fundamental resonance wavelength is predicted by different analytic standing-wave theories to be ~2nl, where n is the dielectric refractive index. Thus, for the dielectrics SiO2, AlN, and TiO2, l values of a few microns give fundamentals in the 8-12 micron LWIR wavelength region. Agreement of observed fundamental resonance wavelength with theory is better for t/l > ~0.2. Harmonics at shorter …

Go to article

Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar Jan 2018

Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar

Electronic Theses and Dissertations

Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal and anomalous dispersion regimes. In the anomalous dispersion regime, the nonlinearity leads to a formation of spatiotemporal 3-D solitons. Unlike in single-mode fibers, these solitons are not unique and their properties can be modified …

Go to article

Split Aptameric Turn-On Fluorescence Sensor For Detection Of Sequence Specific Nucleic Acid At Ambient Temperature, Nanami Kikuchi Jan 2018

Split Aptameric Turn-On Fluorescence Sensor For Detection Of Sequence Specific Nucleic Acid At Ambient Temperature, Nanami Kikuchi

Electronic Theses and Dissertations

Nucleic acid amplification tests (NAATs) enable sensitive detection of low density infections that microscopy and rapid diagnostic test are not capable of detecting. They enable quantitative and qualitative nucleic acid detection, genotype analysis, and single nucleotide polymorphism (SNP) detection. Current state of the art molecular probes used with NAATs includes molecular beacon (MB), Taqman and its variations. This work presents novel molecular probe designed from Spinach and Dapoxyl aptamers. The aptamers are split into two parts (split aptamer), allowing greater sensitivity and selectivity towards fully complementary nucleic acid analyte. The major advantage of split aptamer probe over state-of-the-art fluorescent probes …

Go to article

Optical Properties Of Single Nanoparticles And Two-Dimensional Arrays Of Plasmonic Nanostructures, Yadong Zhou Jan 2018

Optical Properties Of Single Nanoparticles And Two-Dimensional Arrays Of Plasmonic Nanostructures, Yadong Zhou

Electronic Theses and Dissertations

The tunability of plasmonic properties of nanomaterials makes them promising in many applications such as molecular detection, spectroscopy techniques, solar energy materials, etc. In the thesis, we mainly focus on the interaction between light with single nanoparticles and two-dimensional plasmonic nanostructures using electrodynamic methods. The fundamental equations of electromagnetic theory: Maxwell's equations are revisited to solve the problems of light-matter interaction, particularly the interaction of light and noble nanomaterials, such as gold and silver. In Chapter 1, Stokes parameters that describe the polarization states of electromagnetic wave are presented. The scattering and absorption of a particle with an arbitrary shape …

Go to article

Design, Synthesis, Stability, And Photocatalytic Studies Of Sustainable Metal-Organic Frameworks, Matthew Logan Jan 2018

Design, Synthesis, Stability, And Photocatalytic Studies Of Sustainable Metal-Organic Frameworks, Matthew Logan

Electronic Theses and Dissertations

The presented dissertation focuses on the design, synthesis, and characterization of metal-organic frameworks (MOFs) composed of earth-abundant elements the exhibit photoredox activity and studied their application as heterogeneous photocatalysts in organic synthesis and in solar-to-chemical energy conversion. In particular, the structure-property relationships of titanium-based MOFs relating the structure of the organic building unit and the photophysical and photochemical activity of the solid material is studied. The first novel family of seven MOFs isoreticular to MIL-125-NH2, includes functionalized with N-alkyl groups with increasing chain length (methyl to heptyl) and with varying connectivity (primary or secondary). The functionalized materials displayed reduced optical …

Go to article

Practical Dynamic Transactional Data Structures, Pierre Laborde Jan 2018

Practical Dynamic Transactional Data Structures, Pierre Laborde

Electronic Theses and Dissertations

Multicore programming presents the challenge of synchronizing multiple threads. Traditionally, mutual exclusion locks are used to limit access to a shared resource to a single thread at a time. Whether this lock is applied to an entire data structure, or only a single element, the pitfalls of lock-based programming persist. Deadlock, livelock, starvation, and priority inversion are some of the hazards of lock-based programming that can be avoided by using non-blocking techniques. Non-blocking data structures allow scalable and thread-safe access to shared data by guaranteeing, at least, system-wide progress. In this work, we present the first wait-free hash map which …

Go to article

Necessary Conditions For Open-Ended Evolution, Lisa Soros Jan 2018

Necessary Conditions For Open-Ended Evolution, Lisa Soros

Electronic Theses and Dissertations

Evolution on Earth is widely considered to be an effectively endless process. Though this phenomenon of open-ended evolution (OEE) has been a topic of interest in the artificial life community since its beginnings, the field still lacks an empirically validated theory of what exactly is necessary to reproduce the phenomenon in general (including in domains quite unlike Earth). This dissertation (1) enumerates a set of conditions hypothesized to be necessary for OEE in addition to (2) introducing an artificial life world called Chromaria that incorporates each of the hypothesized necessary conditions. It then (3) describes a set of experiments with …

Go to article

Analysis And Design Of Non-Hermitian Optical Systems, Ali Kazemi Jahromi Jan 2018

Analysis And Design Of Non-Hermitian Optical Systems, Ali Kazemi Jahromi

Electronic Theses and Dissertations

From a very general perspective, optical devices can be viewed as constructions based on the spatial engineering of the optical index of refraction. Sculpting the real part of the refractive index produces the wide variety of known passive optical devices, such as waveguides, resonators, gratings, among a plethora of other possibilities for managing the transport of light. Less attention has been directed to engineering the imaginary part of the refractive index – that is responsible for optical gain and absorption – in conjunction with the real part of the refractive index. Optical gain is the building block of amplifiers and …

Go to article

Examining The Issue Of Compliance With Personal Protective Equipment Among Wastewater Workers Across The Southeast Region Of The United States, Tamara L. Wright Jan 2018

Examining The Issue Of Compliance With Personal Protective Equipment Among Wastewater Workers Across The Southeast Region Of The United States, Tamara L. Wright

Electronic Theses and Dissertations

Wastewater workers are exposed to different occupational hazards such as chemicals, gases, viruses, and bacteria. Personal Protective Equipment (PPE) is a significant factor that can reduce or increase the probability of an accident from hazardous exposures to chemicals and microbial contaminants. The purpose of this study was to identify wastewater worker’s beliefs and practices on wearing PPE and protections offered by PPE through the integration of the Health Belief Model (HBM). Participants were workers in the wastewater industry, which included wastewater operators, laboratory analysts, maintenance workers, wastewater collection workers, equipment operators, managers, and supervisors (n=272). The instrument was a self-administered …

Go to article

Some New And Generalized Distributions Via Exponentiation, Gamma And Marshall-Olkin Generators With Applications, Hameed Abiodun Jimoh Jan 2018

Some New And Generalized Distributions Via Exponentiation, Gamma And Marshall-Olkin Generators With Applications, Hameed Abiodun Jimoh

Electronic Theses and Dissertations

Three new generalized distributions developed via completing risk, gamma generator, Marshall-Olkin generator and exponentiation techniques are proposed and studied. Structural properties including quantile functions, hazard rate functions, moment, conditional moments, mean deviations, R\'enyi entropy, distribution of order statistics and maximum likelihood estimates are presented. Monte Carlo simulation is employed to examine the performance of the proposed distributions. Applications of the generalized distributions to real lifetime data are presented to illustrate the usefulness of the models.

Go to article

First Prev Next Last