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Articles 121 - 150 of 1853
Full-Text Articles in Physical Sciences and Mathematics
Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan
Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan
Dissertations, Theses, and Masters Projects
During the last decade, Trusted Execution Environment (TEE) provided by ARM TrustZone had become one of the most popular techniques to build security on mobile devices. On a TrustZone-enabled system, the software can execute in either Secure World (trusted) and Normal World (untrusted). Meanwhile, along with the expeditious development of TrustZone technology, the security of TEE is also challenged by dealing with more and more on-board hardware and in-TEE applications. In this dissertation, we explicitly study the security of ARM TrustZone technology with the latest ARM architecture in three aspects. First, we study the security of the TrustZone-assisted asynchronous introspection. …
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Dissertations, Theses, and Masters Projects
Cultural eutrophication, the overproduction of phytoplankton biomass in response to increased nutrient inputs directly associated with human activities, is a major threat to the health of Chesapeake Bay. Strict regulations, which require a reduction in nutrient loading from all sources, have been a key component to restoration efforts. Water reclamation facilities (WRFs), which discharge effluent containing nitrogen (N) and other nutrients into receiving waters, have implemented upgrades in an effort to comply with regulations. These improvements have decreased the concentration of highly labile dissolved inorganic N (DIN), leaving behind significant concentrations of dissolved organic N (DON) whose bioavailability, and therefore …
Quantitative Analysis Of Ekg And Blood Pressure Waveforms, Denise Erin Mckaig
Quantitative Analysis Of Ekg And Blood Pressure Waveforms, Denise Erin Mckaig
Dissertations, Theses, and Masters Projects
In the intensive care unit (ICU) of a hospital, patients are monitored continuously and the data on those patients provide powerful diagnostic tools for the medical community. However, the patient data creates incredibly large data sets with instruments measuring multiple signals simultaneously. This work seeks to improve monitoring techniques through analysis of large data sets from former ICU patients. By knowing the outcomes of patients in the past, can we detect patterns to diagnose future patients while also reducing the amount of recorded information? This thesis first seeks to improve methods of storing infant electrocardiograms (EKGs) by reducing the full …
Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang
Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang
Dissertations, Theses, and Masters Projects
Unhealthy dietary habits (such as eating disorders, eating too fast, excessive energy intake, and chewing side preference) are major causes of some chronic diseases, including obesity, heart disease, digestive system disease, and diabetes. Dietary monitoring is necessary and important for patients to change their unhealthy diet and eating habits. However, the existing monitoring methods are either intrusive or not accurate enough. In this dissertation, we present our efforts to use wearable motion sensors to sense mastication dynamics for continuous dietary monitoring. First, we study how to detect a subject's eating activity and count the number of chews. We observe that …
Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras
Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras
Dissertations, Theses, and Masters Projects
Vanadium Dioxide (VO2) is a strongly correlated material which has been studied for many decades. VO2 has been proposed for uses in technologies such as optical modulators, IR modulators, optical switches and Mott memory devices. These technologies are taking advantage of VO2’s insulator to metal transition (IMT) and the corresponding changes to the optical and material properties. The insulator to metal transition in VO2 can be accessed by thermal heating, applied electric field, or ultra-fast photo induced processes. Recently, thin films of VO2 grown on Titanium Dioxide doped with Niobium (TiO2:Nb), have shown promise as a possible UV photo detector …
Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su
Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su
Dissertations, Theses, and Masters Projects
Production software packages have become increasingly complex with millions of lines of code, sophisticated control and data flow, and references to a hierarchy of external libraries. This complexity often introduces performance inefficiencies across software stacks, making it practically impossible for users to pinpoint them manually. Performance profiling tools (a.k.a. profilers) abound in the tools community to aid software developers in understanding program behavior. Classical profiling techniques focus on identifying hotspots. The hotspot analysis is indispensable; however, it can hardly diagnose whether a resource is being used in a productive manner that contributes to the overall efficiency of a program. Consequently, …
Exploring Heterogeneous Architectures With Tools And Applications, Du Shen
Exploring Heterogeneous Architectures With Tools And Applications, Du Shen
Dissertations, Theses, and Masters Projects
Heterogeneous architectures have become popular due to programming flexibility and energy efficiency. Heterogeneous architectures include GPU accelerators, and memory subsystems consisting fast and slow components. Achieving high performance for programs running on heterogeneous architectures requires sophisticated tools and applications. They either lack hardware support for fast memory component, or provide complex programming model, which puts extra burdens on compilers and programmers. However, existing tools either rely on simulators or lack support across different GPU architectures, runtime or driver versions. Thus, they only provide insufficient insights. In the first project, we develop DataPlacer, a profiling tool to provide guidance for data …
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
Dissertations, Theses, and Masters Projects
Upon cooling past a critical temperature Tc = 340 K Vanadium dioxide (VO2) exhibits a metal-insulator transition (MIT) from a metallic rutile R to an insulating monoclinic M1 phase. Other insulating phases, a monoclinic M2 and triclinic T, have been identifed and are accessible via strain or doping. Despite decades of research, the nature of the VO2 MIT is still not fully understood. In this work we present ab-initio hybrid density functional theory (DFT) calculations on the insulating phases, compare the results to experimental measurements and discuss their implications on our understanding of the VO2 MIT. Recent measurements on M1 …
Deep Learning In Software Engineering, Cody Watson
Deep Learning In Software Engineering, Cody Watson
Dissertations, Theses, and Masters Projects
Software evolves and therefore requires an evolving field of Software Engineering. The evolution of software can be seen on an individual project level through the software life cycle, as well as on a collective level, as we study the trends and uses of software in the real world. As the needs and requirements of users change, so must software evolve to reflect those changes. This cycle is never ending and has led to continuous and rapid development of software projects. More importantly, it has put a great responsibility on software engineers, causing them to adopt practices and tools that allow …
Competing And Cooperating Orders In The Three-Band Hubbard Model: A Comprehensive Quantum Monte Carlo And Generalized Hartree-Fock Study, Adam Chiciak
Dissertations, Theses, and Masters Projects
Significant progress has been made in studying strongly correlated electronic systems with major focus on understanding high-temperature superconductivity. At the center of these studies are the so-called cuprates, which are characterized by a quasi-2D Copper-Oxide plane in which superconductivity is believed to arise. From the theoretical point of view, the complex electronic structure of these materials makes a fully ab initio many-body computation a formidable task, so we are forced to focus on minimal models that can reproduce the physics, the most well known of which is known as the Hubbard Model, which relies on the Zhang-Rice singet notion to …
Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang
Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang
Dissertations, Theses, and Masters Projects
Graphics Processing Unit (GPU)-based architectures have become the default accelerator choice for a large number of data-parallel applications because they are able to provide high compute throughput at a competitive power budget. Unlike CPUs which typically have limited multi-threading capability, GPUs execute large numbers of threads concurrently to achieve high thread-level parallelism (TLP). While the computation of each thread requires its corresponding data to be loaded from or stored to the memory, the key to supporting the high TLP of GPUs lies in the high bandwidth provided by the GPU memory system. However, with the continuous scaling of GPUs, the …
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Dissertations, Theses, and Masters Projects
In this thesis we investigate the phenomenology of beyond the Standard Model scenarios with extra scalar fields. A review and motivation of extended electroweak symmetry breaking is presented. Then we address observational evidence of new physics such as possible lepton flavor violating processes and the relic abundance of dark matter by implementing models with three Higgs doublets. The complementarity between theoretical restrictions and experimental bounds on some of the predicted signals is leveraged to sharpen the allowed parameter space. After that we study embeddings of two-Higgs doublets into the Randall-Sundrum model with emphasis on the scalar fluctuations of the metric …
Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati
Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati
Dissertations, Theses, and Masters Projects
Multi-photon nonlinear processes in atoms have served as important tools for quantum metrology, quantum communications, and quantum sensing. In this thesis, we experimentally address the interplay of various multi-photon Raman processes in hot Rb vapor, with the four-wave mixing (FWM) process being a central theme. FWM is the nonlinear response of a medium to a strong optical pump field inelastically scattering off atomic resonances and resulting in the generation of additional photons in different modes. FWM is a detrimental, but inherent part of electromagnetically induced transparency (EIT) and Raman based quantum memories. However, we were able to weaken the four-photon …
Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao
Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao
Dissertations, Theses, and Masters Projects
Human behavior recognition and analysis have been considered as a core technology that can facilitate a variety of applications. However, accurate detection and recognition of human behavior is still a big challenge that attracts a lot of research efforts. Among all the research works, motion sensors-based human behavior recognition is promising as it is low cost, low power, and easy to carry. In this dissertation, we use motion sensors to study human behaviors. First, we present Ultigesture (UG) wristband, a hardware platform for detecting and analyzing human behavior. The hardware platform integrates an accelerometer, gyroscope, and compass sensor, providing a …
Impacts Of Physical Transport On Estuarine Phytoplankton Dynamics And Harmful Algal Blooms, Qubin Qin
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 role of horizontal …
On Enhancing Security Of Password-Based Authentication, Yue Li
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 …
Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson
Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson
Dissertations, Theses, and Masters Projects
Two-dimensional (2D) materials, including graphene and graphene oxide (GO), are a subject of interest for many researchers due to their exceptional properties (strength, conductivity, etc.). These materials, comprised of atomically-thin sheets, may naturally occur stacked together like sheets of paper, but their most interesting properties emerge when separated into individual layers. However, scaling up the processes used to isolate single sheets of some of these materials, particularly graphene, has proven problematic. They can be fiercely resistant to exfoliation, difficult to disperse, and have a worrying propensity to restack. All these problems contribute to the great difficulty these fascinating materials have …
Improving Wifi Sensing And Networking With Channel State Information, Yongsen Ma
Improving Wifi Sensing And Networking With Channel State Information, Yongsen Ma
Dissertations, Theses, and Masters Projects
In recent years, WiFi has a very rapid growth due to its high throughput, high efficiency, and low costs. Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency-Division Multiplexing (OFDM) are two key technologies for providing high throughput and efficiency for WiFi systems. MIMO-OFDM provides Channel State Information (CSI) which represents the amplitude attenuation and phase shift of each transmit-receiver antenna pair of each carrier frequency. CSI helps WiFi achieve high throughput to meet the growing demands of wireless data traffic. CSI captures how wireless signals travel through the surrounding environment, so it can also be used for wireless sensing purposes. This dissertation …
Scattering A Bose-Einstein Condensate Off A Modulated Barrier, Andrew James Pyle
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. …
Beyond The Standard Model: Flavor Symmetry, Nonperturbative Unification, Quantum Gravity, And Dark Matter, Shikha Chaurasia
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 in …
Electronic Properties Of Two-Dimensional Van Der Waals Systems, Yohanes Satrio Gani
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 …
Investigating The Molecular Choreography Of Atmospherically Relevant Molecules: A Dynamics Study, Kenneth Jacob Blackshaw
Investigating The Molecular Choreography Of Atmospherically Relevant Molecules: A Dynamics Study, Kenneth Jacob Blackshaw
Dissertations, Theses, and Masters Projects
Investigating and understanding the chemistry of the atmosphere has historically been an important research topic. This importance has only strengthened in the recent decades as technological advancements have drastically increased anthropogenic emissions of hydrocarbons and nitroaromatic compounds. Indeed, we are in an era of unprecedented change of the chemical composition of the troposphere and never before has an in-depth understanding of atmospheric chemical properties been more sought-after. This study seeks to fill that need by probing the molecular dynamics of atmospherically relevant molecules through the use of velocity map imaging (VMI). In particular, we utilize VMI to study the photolysis …
Optimization Approaches For Open-Locating Dominating Sets, Daniel Blair Sweigart
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 …
Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus
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 promise an improved …
Controlling Infectious Disease: Prevention And Intervention Through Multiscale Models, Adrienna N. Bingham
Controlling Infectious Disease: Prevention And Intervention Through Multiscale Models, Adrienna N. Bingham
Dissertations, Theses, and Masters Projects
Controlling infectious disease spread and preventing disease onset are ongoing challenges, especially in the presence of newly emerging diseases. While vaccines have successfully eradicated smallpox and reduced occurrence of many diseases, there still exists challenges such as fear of vaccination, the cost and difficulty of transporting vaccines, and the ability of attenuated viruses to evolve, leading to instances such as vaccine derived poliovirus. Antibiotic resistance due to mistreatment of antibiotics and quickly evolving bacteria contributes to the difficulty of eradicating diseases such as tuberculosis. Additionally, bacteria and fungi are able to produce an extracellular matrix in biofilms that protects them …
Investigation Of Pattern Formation In Marine Environments Through Mathematical Modeling And Analysis Of Remotely Sensed Data, Sofya Zaytseva
Investigation Of Pattern Formation In Marine Environments Through Mathematical Modeling And Analysis Of Remotely Sensed Data, Sofya Zaytseva
Dissertations, Theses, and Masters Projects
Pattern formation in ecological systems refers to a nonuniform distribution of animal and plant species across a landscape. Pattern formation can be observed in many aquatic and terrestrial systems and can provide important insights into their dynamics and ability to cope with environmental changes. In this dissertation, we focus on pattern formation in tidal marshes and oyster reefs, two important habitats that provide a number of essential ecosystem services. Both of these systems have also experienced dramatic losses, prompting much research to investigate their dynamics as and viable restoration and management strategies. The first part of this dissertation focuses on …
Complex Mixtures: Identifying And Characterizing Secondary Organic Aerosols, Emma Quinn Walhout
Complex Mixtures: Identifying And Characterizing Secondary Organic Aerosols, Emma Quinn Walhout
Dissertations, Theses, and Masters Projects
Complex organic mixtures in the environment can contain hundreds to thousands of different organic molecules, and their composition and reactivity can have important environmental implications. In addition to gases, the atmosphere is made of a variety of small liquids and solids called aerosols. These aerosols have large impacts on human health, climate, and atmospheric chemical reactions. Here, secondary organic aerosol (SOA) from the ozonolysis of α-pinene is characterized. The atmospheric lifetime of SOA is very uncertain, but recent laboratory and modeling studies have demonstrated that photolysis is potentially an important process for organic mass loss from aerosol particles.1-5 Photolysis modifies …
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 …
Applying The Concept Of Thresholds In Ecotoxicology With Focus On The Joint Effects Of Habitat Fragmentation And Contamination, Marcos Krull
Applying The Concept Of Thresholds In Ecotoxicology With Focus On The Joint Effects Of Habitat Fragmentation And Contamination, Marcos Krull
Dissertations, Theses, and Masters Projects
A threshold can be defined as the point where small changes in an environmental driver produce an abrupt change within a biological system. These changes can occur at different levels of organization, from organisms to ecosystems. Although thresholds seem to be receiving more attention by ecotoxicologist, not much is known about how contaminants cause or affect thresholds at the landscape level, such as habitat fragmentation thresholds. Habitat fragmentation thresholds can occur due to rapid changes in the landscape structure after a certain amount of habitat is lost, which can cause abrupt effects on the movement of organisms, population abundance and …
Human Dimensions Of A Participatory, Collaborative Modeling Process - Oysterfutures, Taylor Dawn Goelz
Human Dimensions Of A Participatory, Collaborative Modeling Process - Oysterfutures, Taylor Dawn Goelz
Dissertations, Theses, and Masters Projects
Participatory, collaborative modeling processes represent a unique decision-making technique within natural resources management that allows for the combination of stakeholder involvement with the analytical and predictive power of scientific models. The continued use of participatory modeling within decision-making processes depends in part upon the willingness of stakeholders to participate. Continued participation of stakeholders is key to the persistence and overall success of these processes, and yet limited information exists concerning the impacts of these processes on participants. The consideration of human dimensions advances our understanding of the design and function of participatory modeling processes, including their ability to create consensus …