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University of Central Florida

Theses/Dissertations

2017

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Full-Text Articles in Physical Sciences and Mathematics

Weakly Labeled Action Recognition And Detection, Waqas Sultani Jan 2017

Weakly Labeled Action Recognition And Detection, Waqas Sultani

Electronic Theses and Dissertations

Research in human action recognition strives to develop increasingly generalized methods that are robust to intra-class variability and inter-class ambiguity. Recent years have seen tremendous strides in improving recognition accuracy on ever larger and complex benchmark datasets, comprising realistic actions "in the wild" videos. Unfortunately, the all-encompassing, dense, global representations that bring about such improvements often benefit from the inherent characteristics, specific to datasets and classes, that do not necessarily reflect knowledge about the entity to be recognized. This results in specific models that perform well within datasets but generalize poorly. Furthermore, training of supervised action recognition and detection methods …

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Quantification Of Non-Stoichiometry And Impurities In Transparent Yag Ceramics By Laser-Induced Breakdown Spectroscopy (Libs), Sudeep Pandey Jan 2017

Quantification Of Non-Stoichiometry And Impurities In Transparent Yag Ceramics By Laser-Induced Breakdown Spectroscopy (Libs), Sudeep Pandey

Electronic Theses and Dissertations

Transparent ceramics are an important class of optical materials with applications in street-lighting, high-strength windows, electro- and magneto-optical isolators, high-power laser gain media and nuclear radiation detectors. Compared to single-crystal growth, ceramic processing enables size scalability, near net-shape forming and prevents issues associated with dopant segregation and inhomogeneity, such as stress-induced birefringence and wavefront distortions. The fabrication of high optical grade ceramics by route of powder sintering, relies on a controlled set of techniques preventing the formation of scattering centers (pores and secondary phases) and harmful point defects (color centers, charge-carrier trapping sites). This thesis work investigates a novel approach …

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Mechanochemical Synthesis Of Fuels From Sustainable Sources Utilizing Solid Catalysts, Jacob Todd Jan 2017

Mechanochemical Synthesis Of Fuels From Sustainable Sources Utilizing Solid Catalysts, Jacob Todd

Electronic Theses and Dissertations

Mechanochemistry requires less solvents which results in less waste generation. The question becomes can we apply mechanochemistry to current chemical reactions and reduce the generation of waste. This process can be simple or can be very extensive resulting in the generation of large amounts of waste and very little product. A significant advantage of mechanochemistry is the reduced need for solvents that would be common place for reactions. Mechanochemistry transfers energy to reagents via impacts from milling media. Energy can be transferred to the reagents no matter their state-of-matter. Much of the current studies in mechanochemistry today are done using …

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Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah Jan 2017

Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah

Electronic Theses and Dissertations

Ultrashort pulse lasers are well-established in the scientific community due to the wide range of applications facilitated by their extreme intensities and broad bandwidth capabilities. This thesis will primarily present the design for the Mobile Ultrafast High Energy Laser Facility (MU-HELF) for use in outdoor atmospheric propagation experiments under development at the Laser Plasma Laboratory at UCF. The system is a 100fs 500 mJ Ti-Sapphire Chirped-Pulse Amplification (CPA) laser, operating at 10 Hz. Some background on the generation of very high intensity optical pulses is also presented, alongside an overview of the physics of filamentation. As part of the design …

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Charge And Spin Transport In Low-Dimensional Materials, Amin Ahmadi Jan 2017

Charge And Spin Transport In Low-Dimensional Materials, Amin Ahmadi

Electronic Theses and Dissertations

My research has been focused on two main areas. First, electronic transports in chiral carbon nanotubes in the presence of charged adatoms. To study such systems we employed recursive Greens function technique to evaluate the conductance using the Landauer formula. Comparing with the experimental data, we determined the effective amplitude and the range of scattering potentials. In addition, using a similar approach we explained qualitatively an unusual conductance feature in a metallic carbon nanotube. The second part of my study was concerned to the dynamical spin injection and spin currents in low-dimensional materials. We have developed an atomistic model to …

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High Performance Liquid Crystals For Displays And Spatial Light Modulators, Fenglin Peng Jan 2017

High Performance Liquid Crystals For Displays And Spatial Light Modulators, Fenglin Peng

Electronic Theses and Dissertations

Liquid crystals (LCs) are an amazing class of soft materials which have been widely used in the visible, infrared (IR), millimeter wave, and terahertz spectral regions. Both amplitude modulation (e.g. displays) and phase modulation (e.g. spatial light modulators (SLMs) for adaptive optics and adaptive lens) have been investigated extensively. Thin-film-transistor liquid crystal displays (TFT-LCDs) have become ubiquitous in our daily lives. Its widespread applications span from TVs, monitors, tablets, smartphones, augmented reality, virtual reality, to vehicle displays. LCD shows advantages in 1) high resolution, 2) long lifetime, 3) vivid colors using quantum dots backlight, and 4) high dynamic contrast ratio …

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Coloring Graphs With Forbidden Minors, Martin Rolek Jan 2017

Coloring Graphs With Forbidden Minors, Martin Rolek

Electronic Theses and Dissertations

A graph H is a minor of a graph G if H can be obtained from a subgraph of G by contracting edges. My research is motivated by the famous Hadwiger's Conjecture from 1943 which states that every graph with no Kt-minor is (t − 1)-colorable. This conjecture has been proved true for t ≤ 6, but remains open for all t ≥ 7. For t = 7, it is not even yet known if a graph with no K7-minor is 7-colorable. We begin by showing that every graph with no Kt-minor is (2t − 6)- colorable for t = …

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Pervasive Secure Content Delivery Networks Implementation, Hector Lugo-Cordero Jan 2017

Pervasive Secure Content Delivery Networks Implementation, Hector Lugo-Cordero

Electronic Theses and Dissertations

Over the years, communication networks have been shifting their focus from providing connectivity in a client/server model to providing a service or content. This shift has led to topic areas like Service-Oriented Architecture (SOA), Heterogeneous Wireless Mesh Networks, and Ubiquitous Computing. Furthermore, probably the broadest of these areas which embarks all is the Internet of Things (IoT). The IoT is defined as an Internet where all physical entities (e.g., vehicles, appliances, smart phones, smart homes, computers, etc.), which we interact daily are connected and exchanging data among themselves and users. The IoT has become a global goal for companies, researchers, …

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Jml Template Generation, Kushal Raghav Poojari Jan 2017

Jml Template Generation, Kushal Raghav Poojari

Electronic Theses and Dissertations

The Java Modeling Language (JML) is a behavioral interface specific language designed to specify Java modules (which are Java classes and interfaces). Specifications are used to describe the intended functionality without considering the way it is implemented. In JML, if a user wants to write specifications for a Java file, he or she must undertake several steps. To help automate the process of creating annotations for method specifications, a tool Jmlspec was created. Jmlspec generated a file that refines the source file and has empty placeholders in which one can write specifications. Although Jmlspec worked with older versions of Java, …

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Growth And Doping Of Mos2 Thin Films For Electronic And Optoelectronic Applications, Hussain Abouelkhair Jan 2017

Growth And Doping Of Mos2 Thin Films For Electronic And Optoelectronic Applications, Hussain Abouelkhair

Electronic Theses and Dissertations

MoS2 high absorption coefficient, high mobility, mechanical flexibility, and chemical inertness is very promising for many electronic and optoelectronic applications. The growth of high-quality MoS2 by a scalable and doping compatible method is still lacking. Therefore, the suitable dopants for MoS2 are not fully explored yet. This dissertation consists mainly of four main studies. The first study is on the growth of MoS2 thin films by atmospheric pressure chemical vapor deposition. Scanning electron microscope images revealed the growth of microdomes of MoS2 on top of a smooth MoS2 film. These microdomes are very promising as a broadband omnidirectional light trap …

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Ichetucknee Springs: Measuring The Effects Of Visitors On Water Quality Parameters Through Continuous Monitoring., Sarah Faraji Jan 2017

Ichetucknee Springs: Measuring The Effects Of Visitors On Water Quality Parameters Through Continuous Monitoring., Sarah Faraji

Electronic Theses and Dissertations

Ichetucknee Springs System is in north central Florida, under the jurisdiction of the Suwannee River Water Management District (SRWMD). The Ichetucknee River is one of the most pristine spring-fed rivers in Florida and became a state park in 1970. Over 400,000 people visited the Ichetucknee Springs State Park in 2016. From that total, over 130,000 people came during the tubing season alone (Memorial Day to Labor Day). During the tubing season, only 750 visitors per day are allowed to launch from the North Launch, near the Ichetucknee Head Spring. The park enforces visitor usage of the river during these time …

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Atomic-Scale Simulation Of Physical And Chemical Processes During Space Weathering And Planet Formation, Abrar Quadery Jan 2017

Atomic-Scale Simulation Of Physical And Chemical Processes During Space Weathering And Planet Formation, Abrar Quadery

Electronic Theses and Dissertations

We investigate the mechanisms of space weathering and dust grain collisions, two topics of interests from planetary sciences, using atomic-scale simulations. Space weathering is the change in chemical and physical properties of minerals exposed to solar radiation and micrometeorite bombardment on surfaces of airless planetary bodies like the Moon and asteroids. An understanding of the connection between the surface evolution of the minerals and the underlying thermodynamic and kinetic factors is still missing. We address this issue and determine the time evolution of Frenkel defects in the silicate minerals olivine ((Mg,Fe)$_2$SiO$_4$) and orthopyroxene ((Mg,Fe)SiO$_3$) using molecular dynamics with a pair …

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Time-Resolved Phosphorescence Spectroscopy At Cryogenic Temperatures For The Environmental Analysis Of Polycyclic Aromatic Sulfur Heterocycles In Oil Contaminated Sites., Maha Al-Tameemi Jan 2017

Time-Resolved Phosphorescence Spectroscopy At Cryogenic Temperatures For The Environmental Analysis Of Polycyclic Aromatic Sulfur Heterocycles In Oil Contaminated Sites., Maha Al-Tameemi

Electronic Theses and Dissertations

The large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). A classic example is the analysis of the sixteen polycyclic aromatic hydrocarbons included in the priority pollutants list of the U.S. Environmental Protection Agency (EPA-PAHs). …

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A Universal Electrochemical Biosensor For The Detection Of Nucleic Acids Based On A Four-Way Junction Structure, Dawn Mills Jan 2017

A Universal Electrochemical Biosensor For The Detection Of Nucleic Acids Based On A Four-Way Junction Structure, Dawn Mills

Electronic Theses and Dissertations

Electrochemical hybridization sensors have been explored extensively for analysis of specific nucleic acids. However, commercialization of the platform is hindered by the need for attachment of separate oligonucleotide probes complementary to a RNA or DNA target to an electrode's surface. This dissertation demonstrates that a single probe can be used to analyze several nucleic acid targets of different lengths with high selectivity, low cost and can be regenerated in 30 seconds by a simple water rinse. The universal electrochemical four-way junction (4J)-forming (UE4J) sensor consists of a universal DNA stem-loop (USL) probe attached to the electrode's surface and two adaptor …

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Solving Constraint Satisfaction Problems With Matrix Product States, Sabine Pelton Jan 2017

Solving Constraint Satisfaction Problems With Matrix Product States, Sabine Pelton

Electronic Theses and Dissertations

In the past decade, Matrix Product State (MPS) algorithms have emerged as an efficient method of modeling some many-body quantum spin systems. Since spin system Hamiltonians can be considered constraint satisfaction problems (CSPs), it follows that MPS should provide a versatile framework for studying a variety of general CSPs. In this thesis, we apply MPS to two types of CSP. First, use MPS to simulate adiabatic quantum computation (AQC), where the target Hamiltonians are instances of a fully connected, random Ising spin glass. Results of the simulations help shed light on why AQC fails for some optimization problems. We then …

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High Power Fiber Lasers And Fiber Devices, Zeinab Sanjabieznaveh Jan 2017

High Power Fiber Lasers And Fiber Devices, Zeinab Sanjabieznaveh

Electronic Theses and Dissertations

Fiber lasers and fiber amplifiers have experienced considerable improvements in recent years and demonstrated remarkable power scalability. However, due to high optical intensity in the core, the performance of high power fiber lasers is limited by detrimental nonlinear processes, such as four-wave mixing, self-phase modulation, stimulated Brillouin scattering, and stimulated Raman scattering. To mitigate nonlinear effects, very large mode area (LMA) fibers, which exhibit a mode field diameter larger than 30 ?m have been developed. However, for larger core sizes the discrimination capabilities of conventional fiber designs decrease, consequently, LMA fibers are not strictly single mode which ultimately at high …

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Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger Jan 2017

Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger

Electronic Theses and Dissertations

Quantum Cascade Lasers are a novel source of coherent infrared light, unique in their tunability over the mid-infrared and terahertz range of frequencies. Advances in bandgap engineering and semiconductor processing techniques in recent years have led to the development of highly efficient quantum cascade lasers capable of room temperature operation. Recent work has demonstrated power scaling with broad area quantum cascade lasers by increasing active region width beyond the standard ~10 ?m. Taking into account thermal effects caused by driving a device with electrical power, an experimentally fitted model is developed to predict the optical power output in both pulsed …

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Photothermal Lensing In Mid-Infrared Materials, Justin Cook Jan 2017

Photothermal Lensing In Mid-Infrared Materials, Justin Cook

Electronic Theses and Dissertations

A thorough understanding of laser-materials interactions is crucial when designing and building optical systems. An ideal test method would probe both the thermal and optical properties simultaneously for materials under large optical loads where detrimental thermal effects emerge. An interesting class of materials are those used for infrared wavelengths due to their wide spectral transmission windows and large optical nonlinearities. Since coherent sources spanning the mid-wave and long-wave infrared wavelength regions have only become widely available in the past decade, data regarding their thermal and optical responses is lacking in literature. Photothermal Lensing (PTL) technique is an attractive method for …

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High Dynamic Range Display Systems, Ruidong Zhu Jan 2017

High Dynamic Range Display Systems, Ruidong Zhu

Electronic Theses and Dissertations

High contrast ratio (CR) enables a display system to faithfully reproduce the real objects. However, achieving high contrast, especially high ambient contrast (ACR), is a challenging task. In this dissertation, two display systems with high CR are discussed: high ACR augmented reality (AR) display and high dynamic range (HDR) display. For an AR display, we improved its ACR by incorporating a tunable transmittance liquid crystal (LC) film. The film has high tunable transmittance range, fast response time, and is fail-safe. To reduce the weight and size of a display system, we proposed a functional reflective polarizer, which can also help …

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Two-Component Covalent Inhibitors (Tcci) Of The Human Immunodeficiency Virus Reverse Transcriptase (Hiv-Rt), Carlos Ledezma Jan 2017

Two-Component Covalent Inhibitors (Tcci) Of The Human Immunodeficiency Virus Reverse Transcriptase (Hiv-Rt), Carlos Ledezma

Electronic Theses and Dissertations

The traditional design of nucleoside reverse transcriptase inhibitors (NRTI's) involves the synthesis of chain-terminated nucleoside analogs. HIV-RT has relatively low fidelity which facilitates mutations that confer resistance towards NRTI's, also, drug promiscuity from NRTI's result in various side-effects that lead to poor patient adherence to treatment. We designed and tested two-component covalent inhibitors against HIV-RT. Our inhibitor design results in higher specificity due to its binary approach, which has previously been used in biosensing applications, where both components are necessary for therapeutic effect, and lower chances for mutagenesis because of its inhibitory action. The TCCI approach results in up to …

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Monitoring Crystal Structure Refinements Using Solid-State Nmr Chemical Shift Tensors, Keyton Kalakewich Jan 2017

Monitoring Crystal Structure Refinements Using Solid-State Nmr Chemical Shift Tensors, Keyton Kalakewich

Electronic Theses and Dissertations

Inclusion of lattice-fields in density functional theory (DFT) methods has enabled the accurate calculation of solid-state nuclear magnetic resonance (SSNMR) chemical shift tensors. Calculated 13C and 15N tensors (i.e. 3 principle values per nucleus) can be used to monitor crystal structure refinements and to select the correct structure from a large population of computationally generated candidates. In this dissertation, chapter 2 describes a methodology to improve established crystal structures from three different diffraction techniques involving geometric refinement monitored using SSNMR tensor values. The calculated 13C tensors for three relatively simple organic compounds (i.e. acetaminophen, naphthalene, and adenosine) are shown to …

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Nitrogen-Containing Materials For Mechanochemical Synthesis, Luminescence Analysis, And Heterogeneous Catalysis, David Nash Jan 2017

Nitrogen-Containing Materials For Mechanochemical Synthesis, Luminescence Analysis, And Heterogeneous Catalysis, David Nash

Electronic Theses and Dissertations

Various inorganic nitrogen-containing materials have been exploited for their different properties. Several nitride materials are commercially attractive due to their mechanical properties making them suitable for ceramic industries and wide bandgaps fitting for use as semiconductor and insulator materials, as well as optoelectronics. Nitride materials can exhibit versatility in applications such as the use of gallium nitride to make blue LEDs, nitrides of titanium and silicon being utilized as medical implants for their chemical inertness and hardness, and the heavy use of boron nitride as a solid lubricant in the cosmetic industry. Amines have been used as nitrogen-containing organic ligands …

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Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei Jan 2017

Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei

Electronic Theses and Dissertations

In recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics- enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity …

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Online, Supervised And Unsupervised Action Localization In Videos, Khurram Soomro Jan 2017

Online, Supervised And Unsupervised Action Localization In Videos, Khurram Soomro

Electronic Theses and Dissertations

Action recognition classifies a given video among a set of action labels, whereas action localization determines the location of an action in addition to its class. The overall aim of this dissertation is action localization. Many of the existing action localization approaches exhaustively search (spatially and temporally) for an action in a video. However, as the search space increases with high resolution and longer duration videos, it becomes impractical to use such sliding window techniques. The first part of this dissertation presents an efficient approach for localizing actions by learning contextual relations between different video regions in training. In testing, …

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Adversarial Attacks On Vision Algorithms Using Deep Learning Features, Andy Michel Jan 2017

Adversarial Attacks On Vision Algorithms Using Deep Learning Features, Andy Michel

Electronic Theses and Dissertations

Computer vision algorithms, such as those implementing object detection, are known to be susceptible to adversarial attacks. Small barely perceptible perturbations to the input can cause vision algorithms to incorrectly classify inputs that they would have otherwise classified correctly. A number of approaches have been recently investigated to generate such adversarial examples for deep neural networks. Many of these approaches either require grey-box access to the deep neural net being attacked or rely on adversarial transfer and grey-box access to a surrogate neural network. In this thesis, we present an approach to the synthesis of adversarial examples for computer vision …

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Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken Jan 2017

Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken

Electronic Theses and Dissertations

Glass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the resulting composite's optical properties including refractive index, transmission, dispersion, and thermo-optic coefficient. Optical property evolution was related to the type and amount of the crystal phases formed, since through control of the local …

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Assessing Interactions Between Estuary Water Quality And Terrestrial Land Cover In Hurricane Events With Multi-Sensor Remote Sensing, Chandan Mostafiz Jan 2017

Assessing Interactions Between Estuary Water Quality And Terrestrial Land Cover In Hurricane Events With Multi-Sensor Remote Sensing, Chandan Mostafiz

Electronic Theses and Dissertations

Estuaries are environmentally, ecologically and environmentally important places as they act as a meeting place for land, freshwater and marine ecosystems. They are also called nurseries of the sea as they often provide nesting and feeding habitats for many aquatic plants and animals. These estuaries also withstand the worst of some natural disasters, especially hurricanes. The estuaries as well as the harbored ecosystems undergo significant changes in terms of water quality, vegetation cover etc. and these components are interrelated. When hurricane makes landfall it is necessary to assess the damages as quickly as possible as restoration and recovery processes are …

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Super Resolution Of Wavelet-Encoded Images And Videos, Vildan Atalay Jan 2017

Super Resolution Of Wavelet-Encoded Images And Videos, Vildan Atalay

Electronic Theses and Dissertations

In this dissertation, we address the multiframe super resolution reconstruction problem for wavelet-encoded images and videos. The goal of multiframe super resolution is to obtain one or more high resolution images by fusing a sequence of degraded or aliased low resolution images of the same scene. Since the low resolution images may be unaligned, a registration step is required before super resolution reconstruction. Therefore, we first explore in-band (i.e. in the wavelet-domain) image registration; then, investigate super resolution. Our motivation for analyzing the image registration and super resolution problems in the wavelet domain is the growing trend in wavelet-encoded imaging, …

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Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen Jan 2017

Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen

Electronic Theses and Dissertations

Several metrics are commonly used to evaluate the performance of display devices. In this dissertation, we analyze three key parameters: fast response time, wide color gamut, and high contrast ratio, which affect the final perceived image quality. Firstly, we investigate how response time affects the motion blur, and then discover the 2-ms rule. With advanced low-viscosity materials, new operation modes, and backlight modulation technique, liquid crystal displays (LCDs) with an unnoticeable image blur can be realized. Its performance is comparable to an impulse-type display, like cathode ray tube (CRT). Next, we propose two novel backlight configurations to improve an LCD's …

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Spherical Self-Assembly Of Rous Sarcoma Virus Ca, Probed By Ssnmr And The Structure Of Pap And Reflectin Protein, Xin Qiao Jan 2017

Spherical Self-Assembly Of Rous Sarcoma Virus Ca, Probed By Ssnmr And The Structure Of Pap And Reflectin Protein, Xin Qiao

Electronic Theses and Dissertations

In this dissertation, we investigate the morphology of three different protein assemblies, which are formed by prostate acidic phosphatase, residues 248-286 (PAP39), reflectin and rous sarcoma virus capsid (RSV CA). First of all, the main aim of this research is to study the structure of PAP39 which is derived from protease cleavage of Prostate Acidic Phosphatase. The PAP39 can form fibrils of different morphologies in phosphate-buffered saline (PBS) and NaBiCarb (25 mM sodium bicarbonate and 40 mM sodium phosphate, pH=8.83) buffer conditions, each exhibiting different potentials to enhance the infection of HIV in vitro due to different assemble pathways. In …

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