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Articles 1 - 30 of 37
Full-Text Articles in Physical Sciences and Mathematics
Assessment Of The High-Resolution Sediment Gravity Flow Record In Prince William Sound, Alaska, Elisabeth Rose Clyne
Assessment Of The High-Resolution Sediment Gravity Flow Record In Prince William Sound, Alaska, Elisabeth Rose Clyne
Dissertations, Theses, and Masters Projects
South-Central Alaska is one of the most seismically active and climatologically sensitive places in the world. Within this region, Prince William Sound (PWS) receives abundant sediment from multiple sources, potentially housing a high-resolution environmental record spanning the past 4,000 years. Inputs to PWS are derived from local rivers and glaciers, and may include earthquake- and glacial-outburst-triggered sediment gravity flows. Therefore, this is an ideal location to investigate the long-term record of seismic, glacial, and riverine activity. This study examines the elemental, grain size, and stable isotope signatures in PWS to identify gravity flow deposits and the potential paleoseismic and paleoclimate …
Exploiting Power For Smartphone Security And Privacy, Qing Yang
Exploiting Power For Smartphone Security And Privacy, Qing Yang
Dissertations, Theses, and Masters Projects
Power consumption has become a key issue for smartphone security and privacy protection. In this dissertation, we propose to exploit power for smartphone security, as well as to optimize energy consumption for smartphone privacy. First, we show that public USB charging stations pose a significant privacy risk to smartphone users. We present a side-channel attack that allows a charging station to identify which webpages are loaded while the smartphone is charging. to evaluate this side-channel, we collected power traces of Alexa top 50 websites on multiple smartphones under several conditions, including: varied battery charging level, browser cache enabled/disabled, taps/no taps …
Superconducting Thin Films For The Enhancement Of Superconducting Radio Frequency Accelerator Cavities, Matthew Burton
Superconducting Thin Films For The Enhancement Of Superconducting Radio Frequency Accelerator Cavities, Matthew Burton
Dissertations, Theses, and Masters Projects
Bulk niobium (Nb) superconducting radio frequency (SRF) cavities are currently the preferred method for acceleration of charged particles at accelerating facilities around the world. However, bulk Nb cavities have poor thermal conductance, impose material and design restrictions on other components of a particle accelerator, have low reproducibility and are approaching the fundamental material-dependent accelerating field limit of approximately 50MV/m. Since the SRF phenomena occurs at surfaces within a shallow depth of ~1 µm, a proposed solution to this problem has been to utilize thin film technology to deposit superconducting thin films on the interior of cavities to engineer the active …
Modeling The Gross-Pitaevskii Equation Using The Quantum Lattice Gas Method, Armen M. Oganesov
Modeling The Gross-Pitaevskii Equation Using The Quantum Lattice Gas Method, Armen M. Oganesov
Dissertations, Theses, and Masters Projects
We present an improved Quantum Lattice Gas (QLG) algorithm as a mesoscopic unitary perturbative representation of the mean field Gross Pitaevskii (GP) equation for Bose–Einstein Condensates (BECs). The method employs an interleaved sequence of unitary collide and stream operators. QLG is applicable to many different scalar potentials in the weak interaction regime and has been used to model the Korteweg–de Vries (KdV), Burgers and GP equations. It can be implemented on both quantum and classical computers and is extremely scalable. We present results for 1D soliton solutions with positive and negative internal interactions, as well as vector solitons with inelastic …
Computational Methods Of Lattice Boltzmann Mhd, Christopher Robert Flint
Computational Methods Of Lattice Boltzmann Mhd, Christopher Robert Flint
Dissertations, Theses, and Masters Projects
Lattice Boltzmann (LB) Methods are a somewhat novel approach to Computational Fluid Dynamics (CFD) simulations. These methods simulate Navier-Stokes and magnetohydrodynamics (MHD) equations on the mesoscopic (quasi-kinetic) scale by solving for a statistical distribution of particles rather than attempting to solve the nonlinear macroscopic equations directly. These LB methods allow for a highly parallelizable code since one replaces the difficult nonlinear convective derivatives of MHD by simple linear advection on a lattice. New developments in LB have significantly extended the numerical stability limits of its applicability. These developments include multiple relaxation times (MRT) in the collision operators, maximizing entropy to …
Automatically Documenting Software Artifacts, Boyang Li
Automatically Documenting Software Artifacts, Boyang Li
Dissertations, Theses, and Masters Projects
Software artifacts, such as database schema and unit test cases, constantly change during evolution and maintenance of software systems. Co-evolution of code and DB schemas in Database-Centric Applications (DCAs) often leads to two types of challenging scenarios for developers, where (i) changes to the DB schema need to be incorporated in the source code, and (ii) maintenance of a DCAs code requires understanding of how the features are implemented by relying on DB operations and corresponding schema constraints. On the other hand, the number of unit test cases often grows as new functionality is introduced into the system, and maintaining …
Enhancing Usability And Security Through Alternative Authentication Methods, Nicolas Jorge Van Balen
Enhancing Usability And Security Through Alternative Authentication Methods, Nicolas Jorge Van Balen
Dissertations, Theses, and Masters Projects
With the expanding popularity of various Internet services, online users have be- come more vulnerable to malicious attacks as more of their private information is accessible on the Internet. The primary defense protecting private information is user authentication, which currently relies on less than ideal methods such as text passwords and PIN numbers. Alternative methods such as graphical passwords and behavioral biometrics have been proposed, but with too many limitations to replace current methods. However, with enhancements to overcome these limitations and harden existing methods, alternative authentications may become viable for future use. This dissertation aims to enhance the viability …
Disconnected Diagrams In Lattice Qcd, Arjun Singh Gambhir
Disconnected Diagrams In Lattice Qcd, Arjun Singh Gambhir
Dissertations, Theses, and Masters Projects
In this work, we present state-of-the-art numerical methods and their applications for computing a particular class of observables using lattice quantum chromodynamics (Lattice QCD), a discretized version of the fundamental theory of quarks and gluons. These observables require calculating so called "disconnected diagrams" and are important for understanding many aspects of hadron structure, such as the strange content of the proton. We begin by introducing the reader to the key concepts of Lattice QCD and rigorously define the meaning of disconnected diagrams through an example of the Wick contractions of the nucleon. Subsequently, the calculation of observables requiring disconnected diagrams …
Quantum And Classical Manifestation Of Hamiltonian Monodromy, Chen Chen
Quantum And Classical Manifestation Of Hamiltonian Monodromy, Chen Chen
Dissertations, Theses, and Masters Projects
Integrable Hamiltonian systems are said to display nontrivial monodromy if fundamental action-angle loops defined on phase-space tori change their topological structure when the system is carried around a circuit. It was shown in earlier work that this topological change can be seen in families of trajectories of noninteracting particles; however, that work required use of a very abstract flow in phase space. In this dissertation, we show that the same topological change can occur as a result of application of ordinary forces. We also show how this dynamical phenomenon could be observed experimentally in cold atom systems. Almost everything that …
Data-Driven Radiometric Photo-Linearization, Han Li
Data-Driven Radiometric Photo-Linearization, Han Li
Dissertations, Theses, and Masters Projects
In computer vision and computer graphics, a photograph is often considered a photometric representation of a scene. However, for most camera models, the relation between recorded pixel value and the amount of light received on the sensor is not linear. This non-linear relationship is modeled by the camera response function which maps the scene radiance to the image brightness. This non-linear transformation is unknown, and it can only be recovered via a rigorous radiometric calibration process. Classic radiometric calibration methods typically estimate a camera response function from an exposure stack (i.e., an image sequence captured with different exposures from the …
Deep Learning Software Repositories, Martin White
Deep Learning Software Repositories, Martin White
Dissertations, Theses, and Masters Projects
Bridging the abstraction gap between artifacts and concepts is the essence of software engineering (SE) research problems. SE researchers regularly use machine learning to bridge this gap, but there are three fundamental issues with traditional applications of machine learning in SE research. Traditional applications are too reliant on labeled data. They are too reliant on human intuition, and they are not capable of learning expressive yet efficient internal representations. Ultimately, SE research needs approaches that can automatically learn representations of massive, heterogeneous, datasets in situ, apply the learned features to a particular task and possibly transfer knowledge from task to …
A Global Normal Form For Two-Dimensional Mode Conversion, David Gregory Johnston
A Global Normal Form For Two-Dimensional Mode Conversion, David Gregory Johnston
Dissertations, Theses, and Masters Projects
Mode conversion is a phenomenon that is of interest as a method for heating in fusion reactors. A magnetosonic wave with dispersion relation DMS propagates toward the interior of the plasma, where it excites an ion-hybrid wave with dispersion relation DIH and thereby transfers energy to the plasma. We wish to study this process using ray-based methods. The 2 2 dispersion matrix D, which is, in general, a function of the phase space variables (x; y; kx; ky), must be put into normal form, in which the diagonals of D, identied as the uncoupled dispersion relations, DMS and DIH, Poisson-commute …
Measurement Of The Elastic Ep Cross Section At Q2 = 0.66, 1.10, 1.51 And 1.65 Gev2, Yang Wang
Measurement Of The Elastic Ep Cross Section At Q2 = 0.66, 1.10, 1.51 And 1.65 Gev2, Yang Wang
Dissertations, Theses, and Masters Projects
The nucleon form factors have been investigated by physicists for decades because of its fundamental importance. The world data of the proton magnetic form factor GMp shows that the measurements have been focused on Q2 lower than 5 GeV2 and it has large uncertainties at higher GeV2. Experiment E12-07-108 aims to improve the accuracy of the e − p elastic cross section to better than 2% over a Q2 range of 7 − 14 GeV2. From 2015 to 2016, the e − p elastic cross section was measured over a wide range of Q2 from 0.66 − 12.56 GeV2 at …
Infrared Spectroscopy And Nano-Imaging Of La0.67sr0.33mno3 Films, Peng Xu
Infrared Spectroscopy And Nano-Imaging Of La0.67sr0.33mno3 Films, Peng Xu
Dissertations, Theses, and Masters Projects
Charge transport properties of manganites can be significantly modified by temperature, chemical doping, strain, and interfacial boundaries. In this dissertation, we report studies on broadband far-field infrared spectroscopy and near-field infrared imaging of single crystalline thin films of Sr doped manganite LaMnO3 at 0.33 doping level. at this Sr-doping level, the manganite films undergo a phase transition between a ferromagnetic metallic phase at low temperatures to a paramagnetic, insulating phase at higher temperatures. The films were grown on different substrates with different thicknesses by pulsed laser deposition method. The temperature dependent far-field infrared data on 85 nm thick La0.67Sr0.33MnO3 (LSMO) …
Plasmonic Approaches And Photoemission: Ag-Based Photocathodes, Zhaozhu Li
Plasmonic Approaches And Photoemission: Ag-Based Photocathodes, Zhaozhu Li
Dissertations, Theses, and Masters Projects
Photocathodes play an important role in present large accelerator facilities by providing polarized or un-polarized electron beams. Current state-of-art high polarization photocathodes consist of strained super-lattice GaAs based photocathodes, e.g. GaAs/GaAsP has a quantum efficiency ~1% and polarization ~90% at near-infrared wavelength for the incident light. Despite the advantages offered by metallic photocathodes regarding longer life time, fast response time and low requirements of ultra-high vacuum environment, they have not been put to use due to their low quantum efficiency, even though one can envision several approaches to achieve spin-polarization from them. A possible solution is to apply the Fano …
Optical Control Of Multi-Photon Coherent Interactions In Rubidium Atoms, Gleb Vladimirovich Romanov
Optical Control Of Multi-Photon Coherent Interactions In Rubidium Atoms, Gleb Vladimirovich Romanov
Dissertations, Theses, and Masters Projects
In the last few decades, coherent light-atom interactions have opened unprecedented possibilities for the coherent control of atomic and optical quantum systems, paved the way for the practical realization of quantum information technologies, and allowed for the creation of novel quantum-enhanced sensors. This dissertation investigates the interaction of multiple near-resonant optical fields with hot rubidium atoms under the conditions of electromagnetically induced transparency. The main goal of the presented research is to address some fundamental challenges in using such systems for practical applications. The EIT effect relies on the strong coupling of an optical probe field and a collective long-lived …
Enhancing Energy Efficiency And Privacy Protection Of Smart Devices, Ge Peng
Enhancing Energy Efficiency And Privacy Protection Of Smart Devices, Ge Peng
Dissertations, Theses, and Masters Projects
Smart devices are experiencing rapid development and great popularity. Various smart products available nowadays have largely enriched people’s lives. While users are enjoying their smart devices, there are two major user concerns: energy efficiency and privacy protection. In this dissertation, we propose solutions to enhance energy efficiency and privacy protection on smart devices. First, we study different ways to handle WiFi broadcast frames during smartphone suspend mode. We reveal the dilemma of existing methods: either receive all of them suffering high power consumption, or receive none of them sacrificing functionalities. to address the dilemma, we propose Software Broadcast Filter (SBF). …
An Investigation Of Power Saving And Privacy Protection On Smartphones, Dachuan Liu
An Investigation Of Power Saving And Privacy Protection On Smartphones, Dachuan Liu
Dissertations, Theses, and Masters Projects
With the advancements in mobile technology, smartphones have become ubiquitous in people's daily lives and have greatly facilitated users in many aspects. For a smartphone user, power saving and privacy protection are two important issues that matter and draw serious attentions from research communities. In this dissertation, we present our studies on some specific issues of power saving and privacy protection on a smartphone. Although IEEE 802.11 standards provide Power Save Mode (PSM) to help mobile devices conserve energy, PSM fails to bring expected benefits in many real scenarios. We define an energy conserving model to describe the general PSM …
Formulating Schwinger-Dyson Equations For Qed Propagators In Minkowski Space, Shaoyang Jia
Formulating Schwinger-Dyson Equations For Qed Propagators In Minkowski Space, Shaoyang Jia
Dissertations, Theses, and Masters Projects
The Schwinger-Dyson equations (SDEs) are coupled integral equations for the Green's functions of a quantum field theory (QFT). The SDE approach is the analytic nonperturbative method for solving strongly coupled QFTs. When applied to QCD, this approach, also based on first principles, is the analytic alternative to lattice QCD. However, the SDEs for the n-point Green's functions involves (n+1)-point Green's functions (sometimes (n+2)-point functions as well). Therefore any practical method for solving this infinitely coupled system of equations requires a truncation scheme. When considering strongly coupled QED as a modeling of QCD, naive truncation schemes violate various principles of the …
Shining Light On The Phase Transitions Of Vanadium Dioxide, Tyler J. Huffman
Shining Light On The Phase Transitions Of Vanadium Dioxide, Tyler J. Huffman
Dissertations, Theses, and Masters Projects
The salient feature of the familiar structural transition accompanying the thermally-driven metal-insulator transition in bulk vanadium dioxide (VO2) is a pairing of all the vanadium ions in the monoclinic M¬1 insulating phase. Whether this pairing (unit cell doubling) alone is sufficient to open the energy gap has been the central question of a classic debate which has continued for almost sixty years. Interestingly, there are two less familiar insulating states, monoclinic M2 and triclinic, which are accessible via strain or chemical doping. These phases are noteworthy in that they exhibit distinctly different V-V pairing. With infrared and optical photon spectroscopy, …
Determination Of The Kinematics Of The Qweak Experiment And Investigation Of An Atomic Hydrogen Møller Polarimeter, Valerie Marie Gray
Determination Of The Kinematics Of The Qweak Experiment And Investigation Of An Atomic Hydrogen Møller Polarimeter, Valerie Marie Gray
Dissertations, Theses, and Masters Projects
The Qweak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton (QpW). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer (Q^2) from the electron to the proton. The extraction of QpW from the measured asymmetry requires a precise Q^2 determination. The Qweak experiment had a Q^2 = 24.8 ± 0.1 m(GeV^2) which achieved the goal of an uncertainty of ≤ 0.5%. From the measured asymmetry and Q^2 , QpW was determined to …
Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, Daniel Edward Kaufman
Using High-Resolution Glider Data And Biogeochemical Modeling To Investigate Phytoplankton Variability In The Ross Sea, Daniel Edward Kaufman
Dissertations, Theses, and Masters Projects
As Earth’s climate changes, polar environments experience a disproportionate share of extreme shifts. Because the Ross Sea shelf has the highest annual productivity of any Antarctic continental shelf, this region is of particular interest when striving to characterize current and future changes in Antarctic systems. However, understanding of mesoscale variability of biogeochemical patterns in the Ross Sea and how this variability affects assemblage dynamics is incomplete. Furthermore, it is unknown how the Ross Sea may respond to projected warming, reduced summer sea ice concentrations, and shallower mixed layers during the next century. to investigate these dynamics and explore their consequences …
Highly-Correlated Electron Behavior In Niobium And Niobium Compound Thin Films, Melissa R. Beebe
Highly-Correlated Electron Behavior In Niobium And Niobium Compound Thin Films, Melissa R. Beebe
Dissertations, Theses, and Masters Projects
Electron correlations are the root of many interesting phenomena in materials, including phase transitions such as superconductivity and insulator-to-metal transitions, which are of great interest both for scientific understanding and for many applications. Such phase transitions can often be tailored in thin films, in which the geometry of the material is limited in one dimension. By studying how the physical structure of a thin film affects its correlated electron response, it is possible to obtain useful insight into both the nature of the electron correlations present in the material and how to control them for various applications. Niobium, an elemental …
Parsing The Aggregation- And Photodegradation-Induced Effects Of Rhodamine-Sensitized Tio2 And Zro2 Films, James Cassidy
Parsing The Aggregation- And Photodegradation-Induced Effects Of Rhodamine-Sensitized Tio2 And Zro2 Films, James Cassidy
Dissertations, Theses, and Masters Projects
The impact of rhodamine aggregates on the photophysical properties of rhodamine dyes adsorbed to TiO2 were investigated using diffuse reflectance spectroscopy, steady-state fluorescence, and time-correlated single photon counting (TCSPC). Photocatalyzed de-alkylation of rhodamine dyes containing tertiary amine groups (5-ROX, R101, and RB) was observed on TiO2, which resulted in a ~50 nm hypsochromic shift. Therefore, concentration dependent diffuse reflectance spectra of R560/TiO2 samples, which contained primary amines, demonstrated the formation of H- and J-aggregates at the expense of the monomers. The formation of J-aggregates resulted in FRET between monomers and J-aggregates which yielded a bathochromic shifted fluorescence spectra as a …
Workload Prediction For Efficient Performance Isolation And System Reliability, Ji Xue
Workload Prediction For Efficient Performance Isolation And System Reliability, Ji Xue
Dissertations, Theses, and Masters Projects
In large-scaled and distributed systems, like multi-tier storage systems and cloud data centers, resource sharing among workloads brings multiple benefits while introducing many performance challenges. The key to effective workload multiplexing is accurate workload prediction. This thesis focuses on how to capture the salient characteristics of the real-world workloads to develop workload prediction methods and to drive scheduling and resource allocation policies, in order to achieve efficient and in-time resource isolation among applications. For a multi-tier storage system, high-priority user work is often multiplexed with low-priority background work. This brings the challenge of how to strike a balance between maintaining …
Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann
Ecosystem Services Of Restored Oyster Reefs In A Chesapeake Bay Tributary: Abundance And Foraging Of Estuarine Fishes, Bruce William Pfirrmann
Dissertations, Theses, and Masters Projects
Oyster reef restoration may enhance the production of ecologically or economically important fish species, an ecosystem service, by providing refuge and foraging habitat. Predicting the effects of oyster habitat restoration on fisheries production in Chesapeake Bay requires a better understanding of fish habitat use, trophic dynamics, and the processes leading to production on a habitat-scale. The objective of this thesis was to evaluate the influence of restored subtidal oyster reefs on the abundance and foraging patterns of mobile estuarine fishes. Specifically, I compared the 1) abundance, 2) stomach fullness, 3) diet composition, and 4) daily consumption rate of fishes collected …
Impact Of Climate Variation And Human Adaptation On The Physical Transport Processes And Water Exchange In Chesapeake Bay, Jiabi Du
Dissertations, Theses, and Masters Projects
The efficiencies of water exchanges in both vertical and horizontal directions reflect the overall impact of various physical processes and serve as important indicators of physical control over a variety of ecological and biogeochemical processes. The vertical exchange between surface layers and bottom layers of a waterbody has proved to exert great control over the hypoxic condition, while the horizontal exchange between an estuary and coastal ocean determines the flushing capacity of the estuary and the retention rate of riverine materials. Various processes, such as tidal flushing, tidal mixing, gravitational circulation, and lateral circulation, can affect water exchange. Therefore, water …
Using Water Quality Models In Management - A Multiple Model Assessment, Analysis Of Confidence, And Evaluation Of Climate Change Impacts, Isaac Irby
Dissertations, Theses, and Masters Projects
Human impacts on the Chesapeake Bay through increased nutrient run-off as a result of land-use change, urbanization, and industrialization, have resulted in a degradation of water quality over the last half-century. These direct impacts, compounded with human-induced climate changes such as warming, rising sea-level, and changes in precipitation, have elevated the conversation surrounding the future of water quality in the Bay. The overall goal of this dissertation project is to use a combination of models and data to better understand and quantify the impact of changes in nutrient loads and climate on water quality in the Chesapeake Bay. This research …
Investigating The Charge-Transfer Dynamics Of Single-Molecule Sensitizers, Jenna Tan
Investigating The Charge-Transfer Dynamics Of Single-Molecule Sensitizers, Jenna Tan
Dissertations, Theses, and Masters Projects
Dye-sensitized solar cells (DSSCs) can reduce the cost of photovoltaic electricity generation to meet global energy needs. Optimizing DSSC efficiency requires a detailed understanding of the underlying charge transfer processes at the dye-semiconductor interface. By modifying the sensitizer structure, we gain insight into these charge transfer mechanisms. In this thesis, two hydroxyanthraquinone dyes are compared to investigate the impact of structure on charge-transfer and photobleaching dynamics. A combination of ensemble-averaged and single-molecule spectroscopy approaches are used to interpret the underlying ET kinetics.
Impact Of Climate Change Variables On Nutrient Cycling By Marine Microorganisms In The Southern California Bight And Ross Sea, Antarctica, Jenna Lee Spackeen
Impact Of Climate Change Variables On Nutrient Cycling By Marine Microorganisms In The Southern California Bight And Ross Sea, Antarctica, Jenna Lee Spackeen
Dissertations, Theses, and Masters Projects
Ocean environments are being impacted by climate warming, elevated carbon dioxide (CO2) levels, and shifting nutrient sources and sinks. It is essential to quantify the sensitivity of microorganisms to these effects of global change because they form the base of the marine food web and are an integral component of nutrient cycling on the planet. their role in photosynthesis, nutrient uptake, and transfer of organic matter into higher trophic levels or to the deep ocean via the biological pump render microorganisms key in ecosystem structure and function and in regulating the global climate. The goal of this dissertation research was …