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Impacts Of Physical Transport On Estuarine Phytoplankton Dynamics And Harmful Algal Blooms, Qubin Qin Jan 2019

Impacts Of Physical Transport On Estuarine Phytoplankton Dynamics And Harmful Algal Blooms, Qubin Qin

Dissertations, Theses, and Masters Projects

The spatial and temporal variability of phytoplankton biomass in estuaries is determined by both local processes and transport processes. Local processes include biological processes (e.g., photosynthesis, respiration/excretion, and grazing) and settling, whereas transport processes include advective and diffusive transports. Transport processes have been demonstrated to regulate phytoplankton dynamics significantly by distributing both phytoplankton and other dissolved and particulate substances (e.g., nutrients, salts, sediments, and chromophoric dissolved organic matter). Yet, these transport properties lack a framework that unifies the pieced description of their various effects, and quantification of their importance under various environmental conditions. This dissertation highlights the ...


Scattering A Bose-Einstein Condensate Off A Modulated Barrier, Andrew James Pyle Jan 2019

Scattering A Bose-Einstein Condensate Off A Modulated Barrier, Andrew James Pyle

Dissertations, Theses, and Masters Projects

A quantum pump is a device that transports particles through a circuit with localized time-varying potentials, and without the need for an external applied voltage or chemical potential. Quantum pumping was originally proposed in the context of electron transport in nanowires, but has proven difficult to implement. The ultracold atom approach represents a possible route around the current experimental bottleneck. We present an experiment to study 1D quantum mechanical scattering by an amplitude-modulated barrier. This experiment represents a first step toward implementing a quantum pump for ultracold atoms based on two such barriers modulated out of phase with one another ...


On Enhancing Security Of Password-Based Authentication, Yue Li Jan 2019

On Enhancing Security Of Password-Based Authentication, Yue Li

Dissertations, Theses, and Masters Projects

Password has been the dominant authentication scheme for more than 30 years, and it will not be easily replaced in the foreseeable future. However, password authentication has long been plagued by the dilemma between security and usability, mainly due to human memory limitations. For example, a user often chooses an easy-to-guess (weak) password since it is easier to remember. The ever increasing number of online accounts per user even exacerbates this problem. In this dissertation, we present four research projects that focus on the security of password authentication and its ecosystem. First, we observe that personal information plays a very ...


Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus Jan 2019

Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus

Dissertations, Theses, and Masters Projects

By mining data from Jefferson Lab Hall A experiment E08-014 a new measurement of the 3He elastic cross section at Q^2 ≈ 34 fm^−2 was extracted from a large quasielastic background. This new data point falls approximately halfway between the first and second diffractive minima of the 3He form factors. When combined with recent high Q^2 3He elastic cross section measurements from JLab this new point improves our knowledge of the cross section and form factors at large momentum transfers. The new high Q^2 data motivate a reanalysis of the 3He elastic cross section world data and ...


Gpgpu Reliability Analysis: From Applications To Large Scale Systems, Bin Nie Jan 2019

Gpgpu Reliability Analysis: From Applications To Large Scale Systems, Bin Nie

Dissertations, Theses, and Masters Projects

Over the past decade, GPUs have become an integral part of mainstream high-performance computing (HPC) facilities. Since applications running on HPC systems are usually long-running, any error or failure could result in significant loss in scientific productivity and system resources. Even worse, since HPC systems face severe resilience challenges as progressing towards exascale computing, it is imperative to develop a better understanding of the reliability of GPUs. This dissertation fills this gap by providing an understanding of the effects of soft errors on the entire system and on specific applications. To understand system-level reliability, a large-scale study on GPU soft ...


Beyond The Standard Model: Flavor Symmetry, Nonperturbative Unification, Quantum Gravity, And Dark Matter, Shikha Chaurasia Jan 2019

Beyond The Standard Model: Flavor Symmetry, Nonperturbative Unification, Quantum Gravity, And Dark Matter, Shikha Chaurasia

Dissertations, Theses, and Masters Projects

Despite the vast success of the Standard Model of particle physics, it is no secret that is also has its shortcomings, thus providing incentive to look beyond the Standard Model for solutions. In this thesis we focus in particular on a model of horizontal flavor symmetry, unification via a universal Landau pole, emergent gravity, and dark matter. First we explain the observed hierarchies in the elementary fermion mass spectrum via a model based on the double tetrahedral group, the smallest discrete subgroup of SU(2), while relaxing previous assumptions of supersymmetry. A sequential symmetry breaking process results in a hierarchy ...


Learning Code Transformations Via Neural Machine Translation, Michele Tufano Jan 2019

Learning Code Transformations Via Neural Machine Translation, Michele Tufano

Dissertations, Theses, and Masters Projects

Source code evolves – inevitably – to remain useful, secure, correct, readable, and efficient. Developers perform software evolution and maintenance activities by transforming existing source code via corrective, adaptive, perfective, and preventive changes. These code changes are usually managed and stored by a variety of tools and infrastructures such as version control, issue trackers, and code review systems. Software Evolution and Maintenance researchers have been mining these code archives in order to distill useful insights on the nature of such developers’ activities. One of the long-lasting goal of Software Engineering research is to better support and automate different types of code changes ...


Electronic Properties Of Two-Dimensional Van Der Waals Systems, Yohanes Satrio Gani Jan 2019

Electronic Properties Of Two-Dimensional Van Der Waals Systems, Yohanes Satrio Gani

Dissertations, Theses, and Masters Projects

In this dissertation we study the electronic structure of van der Waals systems. A van der Waals systems is a heterostructure in which the different constituents are held together by van der Waals forces. We study two different types of van der Waals systems: van der Waals systems formed by graphene and a monolayer of NbSe2, van der Waals systems obtained by placing graphene nanoribbons on a two-dimensional crystal. For the first type of systems we build a continuous low-energy effective model that takes into account the presence of a twist angle between graphene and NbSe2, and of spin-orbit coupling ...


Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig Jan 2019

Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig

Dissertations, Theses, and Masters Projects

Microplastic contamination of aquatic environments has only recently caught the attention of scientists, regulators and the public. Microplastics are typically more recalcitrant than naturally occurring polymers and so have the potential to cause a range of issues, including increased exposure of marine life to chemical contaminants sorbed to or leached from microplastics, negative impacts due to ingestion of microplastics by biota, and the potential to carry and transport pathogenic and invasive species long distances. Bio-based, bio-degradable polymers have begun to gain market share as an alternative to traditional petrochemical-based plastics, but not much is known about their impacts in marine ...


Persistence And Extinction Dynamics In Reaction-Diffusion-Advection Stream Population Model With Allee Effect Growth, Yan Wang Jan 2019

Persistence And Extinction Dynamics In Reaction-Diffusion-Advection Stream Population Model With Allee Effect Growth, Yan Wang

Dissertations, Theses, and Masters Projects

The question how aquatic populations persist in rivers when individuals are constantly lost due to downstream drift has been termed the ``drift paradox." Reaction-diffusion-advection models have been used to describe the spatial-temporal dynamics of stream population and they provide some qualitative explanations to the paradox. Here random undirected movement of individuals in the environment is described by passive diffusion, and an advective term is used to describe the directed movement in a river caused by the flow. In this work, the effect of spatially varying Allee effect growth rate on the dynamics of reaction-diffusion-advection models for the stream population is ...


Research On Efficiency And Security For Emerging Distributed Applications, Zijiang Hao Jan 2019

Research On Efficiency And Security For Emerging Distributed Applications, Zijiang Hao

Dissertations, Theses, and Masters Projects

Distributed computing has never stopped its advancement since the early years of computer systems. In recent years, edge computing has emerged as an extension of cloud computing. The main idea of edge computing is to provide hardware resources in proximity to the end devices, thereby offering low network latency and high network bandwidth. However, as an emerging distributed computing paradigm, edge computing currently lacks effective system support. To this end, this dissertation studies the ways of building system support for edge computing. We first study how to support the existing, non-edge-computing applications in edge computing environments. This research leads to ...


Seasonal Variability Of The Co2-System Throughout The Chesapeake Bay Mainstem, Jaclyn Rain Friedman Jan 2019

Seasonal Variability Of The Co2-System Throughout The Chesapeake Bay Mainstem, Jaclyn Rain Friedman

Dissertations, Theses, and Masters Projects

Declining water quality, in addition to hypoxia and eutrophication, may have a significant impact on the seasonality of biogeochemical parameters throughout the mainstem of the Chesapeake Bay. The carbonate (CO2) system in the Chesapeake Bay experiences seasonal and spatial complexities and is influenced by both natural and anthropogenic variability. Although site-specific studies investigating CO2-system variability exist within the Chesapeake Bay, few studies have investigated the seasonality of the CO2-system throughout the entire mainstem. Additionally, recent comprehensive studies investigating over 50 estuaries along the East Coast of the United States suggest that estuarine systems are heterotrophic and act as sources of ...


Optimization Approaches For Open-Locating Dominating Sets, Daniel Blair Sweigart Jan 2019

Optimization Approaches For Open-Locating Dominating Sets, Daniel Blair Sweigart

Dissertations, Theses, and Masters Projects

An Open Locating-Dominating Set (OLD set) is a subset of vertices in a graph such that every vertex in the graph has a neighbor in the OLD set and every vertex has a unique set of neighbors in the OLD set. This can also represent where sensors, capable of detecting an event occurrence at an adjacent vertex, could be placed such that one could always identify the location of an event by the specific vertices that indicated an event occurred in their neighborhood. By the open neighborhood construct, which differentiates OLD sets from identifying codes, a vertex is not able ...


Global Shipping Container Monitoring Using Machine Learning With Multi-Sensor Hubs And Catadioptric Imaging, Victor Esteban Trujillo Jan 2019

Global Shipping Container Monitoring Using Machine Learning With Multi-Sensor Hubs And Catadioptric Imaging, Victor Esteban Trujillo

Dissertations, Theses, and Masters Projects

We describe a framework for global shipping container monitoring using machine learning with multi-sensor hubs and infrared catadioptric imaging. A wireless mesh radio satellite tag architecture provides connectivity anywhere in the world which is a significant improvement to legacy methods. We discuss the design and testing of a low-cost long-wave infrared catadioptric imaging device and multi-sensor hub combination as an intelligent edge computing system that, when equipped with physics-based machine learning algorithms, can interpret the scene inside a shipping container to make efficient use of expensive communications bandwidth. The histogram of oriented gradients and T-channel (HOG+) feature as introduced for ...


Exploring New Paradigms For Mobile Edge Computing, Yutao Tang Nov 2018

Exploring New Paradigms For Mobile Edge Computing, Yutao Tang

Dissertations, Theses, and Masters Projects

Edge computing has been rapidly growing in recent years to meet the surging demands from mobile apps and Internet of Things (IoT). Similar to the Cloud, edge computing provides computation, storage, data, and application services to the end-users. However, edge computing is usually deployed at the edge of the network, which can provide low-latency and high-bandwidth services for end devices. So far, edge computing is still not widely adopted. One significant challenge is that the edge computing environment is usually heterogeneous, involving various operating systems and platforms, which complicates app development and maintenance. in this dissertation, we explore to combine ...


Monitoring Infection Of E. Coli By Bacteriophage T7 Through Mass Spectrometry-Based Proteomics, Amy Swayne Schienschang Nov 2018

Monitoring Infection Of E. Coli By Bacteriophage T7 Through Mass Spectrometry-Based Proteomics, Amy Swayne Schienschang

Dissertations, Theses, and Masters Projects

Mass spectrometry-based proteomics has become an important and versatile tool in analytical chemistry, making sense of complex biological samples and shedding light on the intricate proteomes of living organisms. Bottom-up proteomics studies are used to elucidate the changes in gene expression of bacteriophage T7 over the course of infection of Escherichia coli. E. coli cultures were infected with T7, sampled over time, and proteins were isolated and enzymatically digested. Nanoflow liquid chromatography combined with tandem mass spectrometry was used to detect proteolytic peptides and identify host and phage proteins. Generally, phage proteins were detected on a time scale fitting the ...


Probe Of Electroweak Interference Effects In Non-Resonant Inelastic Electron-Proton Scattering, James Franklyn Dowd Sep 2018

Probe Of Electroweak Interference Effects In Non-Resonant Inelastic Electron-Proton Scattering, James Franklyn Dowd

Dissertations, Theses, and Masters Projects

The Qweak collaboration at Jefferson Lab made the first direct measurement of the proton's weak charge, Q_W^p, via a measurement of the parity-violating asymmetry in elastic e ⃑p scattering with low four-momentum transfer. to meet the high-precision goals, energy-dependent electroweak radiative corrections were applied to the measured asymmetry. The γZ box, □_γZ, where a photon and a Z-boson are simultaneously exchanged, was the most problematic of these corrections. It could not be calculated through the same perturbative methods as the rest of the corrections. The □_γZ correction depends on theoretical models of the γZ interference structure functions, F_1 ...


Development Of Large-Scale Unstructured Grid Storm Surge And Sub-Grid Inundation Models For Coastal Applications, Zhuo Liu Aug 2018

Development Of Large-Scale Unstructured Grid Storm Surge And Sub-Grid Inundation Models For Coastal Applications, Zhuo Liu

Dissertations, Theses, and Masters Projects

Storm surge and inundation induced by hurricanes and nor'easters pose a profound threat to coastal communities and ecosystems. These storm events with powerful winds, heavy precipitation, and strong wind waves can lead to major flooding for cities along U.S. Coasts. Recent examples of Hurricane Irene (2011) in North Carolina and Virginia and Hurricane Sandy (2012) in New York City not only demonstrated the immense destructive power by the storms, but also revealed the obvious, crucial need for improved forecasting of storm tide and inundation. in part I, a large-scale unstructured-grid 3-D barotropic storm tide model SCHISM (Semi-implicit Cross-scale ...


Impact Of Submerged Aquatic Vegetation On Water Quality In Cache Slough Complex, Sacramento-San Joaquin Delta: A Numerical Modeling Study, Xun Cai Aug 2018

Impact Of Submerged Aquatic Vegetation On Water Quality In Cache Slough Complex, Sacramento-San Joaquin Delta: A Numerical Modeling Study, Xun Cai

Dissertations, Theses, and Masters Projects

Submerged aquatic vegetation (SAV) plays a significant role in many aquatic systems, and impacts both physical and ecological quantities. It can baffle currents, attenuate waves, recycle nitrogen and phosphorus from the sediment bed, perform ecosystem function as a primary producer, and provide critical habitat for many aquatic species. Conversely, the invasive SAV, Egeria densa (Brazilian waterweed), in the San Francisco Bay & Delta has been a nuisance since its introduction into the system in the 1960s. It has displaced most of the native submersed aquatic plant species in the Delta and restructured the ecosystem, thus threatening the survival of several endangered ...


Exotic Phases In Attractive Fermions: Charge Order, Pairing, And Topological Signatures, Peter Rosenberg Jul 2018

Exotic Phases In Attractive Fermions: Charge Order, Pairing, And Topological Signatures, Peter Rosenberg

Dissertations, Theses, and Masters Projects

Strongly interacting many-body systems remain a central challenge of modern physics. Recent developments in the field of ultra-cold atomic physics have opened a new window onto this enduring problem. Experimental progress has revolutionized the approach to studying many-body systems and the exotic behaviors that emerge in these systems. It is now possible to engineer and directly measure a variety of models that can capture the essential features of real materials without the added complexity of disorder, impurities, or complicated or irregular geometries. The parameters of these models can be freely tuned with tremendous precision. These experimental realizations are an ideal ...


Quantifying And Explaining Causal Effects Of World Bank Aid Projects, Jianing Simulation Zhao Jul 2018

Quantifying And Explaining Causal Effects Of World Bank Aid Projects, Jianing Simulation Zhao

Dissertations, Theses, and Masters Projects

In recent years, machine learning methods have enabled us to predict with good precision using large training data, such as deep learning. However, for many problems, we care more about causality than prediction. For example, instead of knowing that smoking is statistically associated with lung cancer, we are more interested in knowing that smoking is the cause of lung cancer. With causality, we can understand how the world progresses and how impacts are made on an outcome by influencing the cause. This thesis explores how to quantify the causal effects of a treatment on an observable outcome in the presence ...


Dynamics Of Systems With Hamiltonian Monodromy, Daniel Salmon Jul 2018

Dynamics Of Systems With Hamiltonian Monodromy, Daniel Salmon

Dissertations, Theses, and Masters Projects

A system is said to have monodromy if, when we carry the system around a closed circuit, it does not return to its initial state. The simplest example is the square-root function in the complex plane. A Hamiltonian system is said to have Hamiltonian monodromy if its fundamental action-angle loops do not return to their initial topological state at the end of a closed circuit. These changes in topology of angle loops carry through to other aspects of these systems, including the classical dynamics of families of trajectories, quantum spectra and even wavefunctions. This topological change in the evolution of ...


Computational Investigations Of The Structure And Spectroscopy Of Small Biomolecules In The Gas Phase, Zachary Michael Smith Jul 2018

Computational Investigations Of The Structure And Spectroscopy Of Small Biomolecules In The Gas Phase, Zachary Michael Smith

Dissertations, Theses, and Masters Projects

Small biomolecule systems were interrogated using infrared multiple photon dissociation (IRMPD) action spectroscopy and corresponding quantum chemical calculations with a particular focus on peptide fragmentation and protonation site preference. b2+ and b3+ fragment ions with a terminal lysine homolog residue were investigated using IRMPD in the fingerprint region (1000 cm-1 – 2000 cm-1) and a variety of computational methods. We present the first spectroscopic confirmation of b-ion formation with a lactam structure. Infrared spectra for b2+ fragment system indicate the presence of a mixture of structures, though final determination will require further investigation. The b3+ fragment ion infrared spectra show strong ...


A Measurement Of Nuclear Effects In Deep Inelastic Scattering In Neutrino-Nucleus Interactions, Anne Norrick Jul 2018

A Measurement Of Nuclear Effects In Deep Inelastic Scattering In Neutrino-Nucleus Interactions, Anne Norrick

Dissertations, Theses, and Masters Projects

Neutrino-Nucleus Deep Inelastic Scattering (DIS) events provide a probe into the structure of nucleons within a nucleus that cannot be accessed via charged lepton-nucleus interactions. The MINERvA experiment is stationed in the Neutrinos from the Main Injector (NuMI) beam line at Fermi National Accelerator Laboratory. With the recent increase in average neutrino energy and the greatly increased intensity of the NuMI beam line, projected sensitivities for DIS cross section ratio analyses using MINERvA's suite of nuclear targets (C, CH, Fe and Pb) are greatly increased. an analysis of theMINERvA DIS data on carbon, iron, lead, and plastic has been ...


Extensions Of The Standard Model Higgs Sector, Richard Keith Thrasher Jul 2018

Extensions Of The Standard Model Higgs Sector, Richard Keith Thrasher

Dissertations, Theses, and Masters Projects

The Standard Model is regarded as one of the most successful scientific theories, but there is compelling evidence that it is an incomplete theory of particle physics. There is currently no understanding of the observed baryon asymmetry, the nature of dark matter, and dark energy. Field theoretic considerations indicate parameters in the Standard Model are extremely fine-tuned. This suggests the existence of new physics, accessible at higher energies, to explain these seemingly unnatural tunings. to solve these puzzles, and others not addressed by the Standard Model, many extensions of the Standard Model have been proposed. It is of great importance ...


Investigating Emerging Security Threats In Clouds And Data Centers, Xing Gao Jul 2018

Investigating Emerging Security Threats In Clouds And Data Centers, Xing Gao

Dissertations, Theses, and Masters Projects

Data centers have been growing rapidly in recent years to meet the surging demand of cloud services. However, the expanding scale of a data center also brings new security threats. This dissertation studies emerging security issues in clouds and data centers from different aspects, including low-level cooling infrastructures and different virtualization techniques such as container and virtual machine (VM). We first unveil a new vulnerability called reduced cooling redundancy that might be exploited to launch thermal attacks, resulting in severely worsened thermal conditions in a data center. Such a vulnerability is caused by the wide adoption of aggressive cooling energy ...


Usability, Efficiency And Security Of Personal Computing Technologies, Nancy Carter Jun 2018

Usability, Efficiency And Security Of Personal Computing Technologies, Nancy Carter

Dissertations, Theses, and Masters Projects

New personal computing technologies such as smartphones and personal fitness trackers are widely integrated into user lifestyles. Users possess a wide range of skills, attributes and backgrounds. It is important to understand user technology practices to ensure that new designs are usable and productive. Conversely, it is important to leverage our understanding of user characteristics to optimize new technology efficiency and effectiveness. Our work initially focused on studying older users, and personal fitness tracker users. We applied the insights from these investigations to develop new techniques improving user security protections, computational efficiency, and also enhancing the user experience. We offer ...


Understanding And Enriching Randomness Within Resource-Constrained Devices, Kyle Wallace Jun 2018

Understanding And Enriching Randomness Within Resource-Constrained Devices, Kyle Wallace

Dissertations, Theses, and Masters Projects

Random Number Generators (RNG) find use throughout all applications of computing, from high level statistical modeling all the way down to essential security primitives. A significant amount of prior work has investigated this space, as a poorly performing generator can have significant impacts on algorithms that rely on it. However, recent explosive growth of the Internet of Things (IoT) has brought forth a class of devices for which common RNG algorithms may not provide an optimal solution. Furthermore, new hardware creates opportunities that have not yet been explored with these devices. in this Dissertation, we present research fostering deeper understanding ...


Mixed-Weight Open Locating-Dominating Sets, Robin M. Givens Jun 2018

Mixed-Weight Open Locating-Dominating Sets, Robin M. Givens

Dissertations, Theses, and Masters Projects

The detection and location of issues in a network is a common problem encompassing a wide variety of research areas. Location-detection problems have been studied for wireless sensor networks and environmental monitoring, microprocessor fault detection, public utility contamination, and finding intruders in buildings. Modeling these systems as a graph, we want to find the smallest subset of nodes that, when sensors are placed at those locations, can detect and locate any anomalies that arise. One type of set that solves this problem is the open locating-dominating set (OLD-set), a set of nodes that forms a unique and nonempty neighborhood with ...


Evaluation Of Population Structure And The Interspecific Relationship Of Striped Marlin (Kajikia Audax) And White Marlin (K. Albida) Based On Traditional Or Genome-Wide Molecular Markers, Nadya Mamoozadeh Apr 2018

Evaluation Of Population Structure And The Interspecific Relationship Of Striped Marlin (Kajikia Audax) And White Marlin (K. Albida) Based On Traditional Or Genome-Wide Molecular Markers, Nadya Mamoozadeh

Dissertations, Theses, and Masters Projects

The istiophorid billfishes (marlins, spearfishes, and sailfish) are highly migratory pelagic fishes exhibiting broad and continuous spatial distributions in the Atlantic, Pacific, and Indian oceans. These species are targeted by a number of recreational, commercial, artisanal, and subsistence fisheries worldwide, and are also caught as bycatch in pelagic longline fisheries targeting tunas and swordfish. Though stock assessments have not been conducted for all istiophorids, assessments available for some species indicate that many istiophorid stocks are overfished and/or experiencing overfishing. However, the development of stock-specific recovery efforts is often impeded by a lack of information on basic species biology, including ...