Digital Commons Network^™

Metareasoning For Heuristic Search Using Uncertainty, Tianyi Gu

Doctoral Dissertations

Heuristic search methods are widely used in many real-world autonomous systems. Yet, people always want to solve search problems that are larger than time allows. To address these challenging problems, even suboptimally, a planning agent should be smart enough to intelligently allocate its computational resources, to think carefully about where in the state space it should spend time searching. For finding optimal solutions, we must examine every node that is not provably too expensive. In contrast, to find suboptimal solutions when under time pressure, we need to be very selective about which nodes to examine. In this dissertation, we will …

Synthesis Of Thioacids And Dicarboxylic Acids Derived From Open Β-Lactams For Inhibition Of Metallo-Β-Lactamases, Junfu Chen

Doctoral Dissertations

Antibiotics are important substances that have been used in clinical treatment for over 70 years. Because of overuse and misuse of antibiotics, bacteria developed resistance. However, bacterial resistance towards antibiotics, especially the β-lactam antibiotics, is becoming increasingly threat. Currently, the β-lactam antibiotics are seriously threatened by β-lactamases. Metallo-β-lactamases (MBLs), a sub-class of β-lactamases, have been found in several bacteria since they confer resistance to many different β-lactams, and as a result, the bacteria survive in their presence. A potential treatment is to synthesize inhibitors of MBLs, however, there are no inhibitors synthesized in clinical use. The goal of this project …

High Level Learning Using The Temporal Features Of Human Demonstrated Sequential Tasks, Madison Brandywine Clark-Turner

Doctoral Dissertations

Modelling human-led demonstrations of high-level sequential tasks is fundamental to a number of practical inference applications including vision-based policy learning and activity recognition. Demonstrations of these tasks are captured as videos with long durations and similar spatial contents. Learning from this data is challenging since inference cannot be conducted solely on spatial feature presence and must instead consider how spatial features play out across time. To be successful these temporal representations must generalize to variations in the duration of activities and be able to capture relationships between events expressed across the scale of an entire video.

Contemporary deep learning architectures …

Molecular Architecture Of Rod Photoreceptor Phosphodiesterase In Its Nonactivated And G-Protein Activated States, Michael Irwin

Doctoral Dissertations

The photoreceptor phosphodiesterase (PDE6) plays an important role in the G-protein coupled visual signaling pathway which uses cGMP as a second messenger to convert light stimuli into electrical signals. PDE6 is a tetrameric peripheral membrane protein consisting of two catalytic subunits and two inhibitory subunits and is localized to the outer segment membranes of rod and cone photoreceptors. Mutations in this enzyme are one cause of retinitis pigmentosa and other retinal degenerative diseases resulting in blindness or visual dysfunction that lack adequate therapeutic intervention due to inadequate knowledge of PDE6 structure and regulation PDE6 is tightly regulated in the nonactivated …

Cognitive Buffer-Aided Cooperative Networks: Scheduling, Resource Allocation, And Performance Analysis, Omid Moghimi Kandelusy

Doctoral Dissertations

Electromagnetic spectrum, as a limited resource, is prone to scarcity due to the astronomical growth in demands for ubiquitous wireless connectivity in the past few decades. Meeting such an ever-growing demand is contingent upon optimizing the spectrum utilization. In this context, dynamic spectrum access policies, such as spectrum sharing, are promising solutions to mitigate the spectrum gridlock. Spectrum sharing networks are allowed to operate on the licensed frequency bands as the secondary users of the spectrum provided that the licensed primary network is protected from any disruptive interference due to the coexistence. The stringent constraints on the secondary network for …

Multiscale Dynamics Of Energy Transfer Within The Electron Diffusion Region Of Magnetic Reconnection, Dominic Payne

Doctoral Dissertations

During the process of magnetic reconnection, anti-parallel magnetic fields with embedded plasma particles converge and undergo a dramatic topological reconfiguration in the electron diffusion region (EDR) while releasing some of the stored magnetic energy directly into the particles. This process is ubiquitous in natural plasmas, and is responsible for many of the explosive phenomena observed in the Earth's magnetosphere and on the sun. While it has long been established that magnetic reconnection is a plasma energization process, it is still unclear what mechanisms underlie the energy conversion from fields to particles, particularly in the EDR where magnetohydrodynamic (MHD) approximations are …

The Application Of Iron-Based Materials In Aqueous Energy Storage, Fenghua Guo

Doctoral Dissertations

Aqueous energy storage has been an important part of battery research for its cost-effective, environmentally benign, and robust nature. Iron-based materials, including iron hydroxides and iron oxides, are widely investigated as electrode materials for their extremely low cost and sufficient discharge capacity. Iron-based electrode materials were often operated in strong alkaline electrolytes, experiencing either slow reaction kinetics, severe side reactions, or significant capacity loss over cycling. This research focused on the application of iron-based materials in aqueous electrolytes with low alkalinity. This research showed that the synthesized γ-FeOOH measured with a cocktail electrolyte of sodium sulfate and sodium hydroxide demonstrated …

Ligand Design In C-Functionalized Cobalt Cyclams For Hybrid Photocatalytic Co2 Reduction, Ethan Edward Jarvis

Doctoral Dissertations

Global climate change is one of the most significant risks to both the planet and all life on it. The largest contributor to this ever-growing threat is CO2 and its continued emission into the atmosphere. As a result, many scientists are researching CO2 reduction processes to help slow and potentially reverse the climate change by reducing the atmospheric levels of CO2. Ideally, these reduction processes convert CO2 into useful materials such as hydrocarbon-based fuels such as methanol or ethanol, which could also help remove our dependence on finite natural energy resources. CO2 reduction is challenging to do efficiently however, due …

Preventing Violence Among Adolescents: The Many Roles Of School Personnel, Andrew Rizzo

Doctoral Dissertations

Youth violence can encompass a range of types of harmful behaviors that each have their own definitions, high prevalence rates, and litany of negative consequences for both adolescent victims and perpetrators. It includes behaviors that can be labeled based on the nature of the act itself such as physical assault, verbal harassment, relational violence, sexual violence, or cyber violence (Basile et al., 2020; Hasbrouck, 2020). One of the primary avenues of youth violence prevention is through school-based programs that often involve school personnel (Butchart et al., 2019). This dissertation contributes to the extant knowledge about school personnel’s impact on preventing …

Three Essays In Applied Microeconomics: Spillover Effects Of Anti Discrimination And Anti Violence Policies, Gokhan Kumpas

Doctoral Dissertations

In this research, I examine the intended and unintended consequences of three highly debated policies at the state and federal level: enactment of Title IX, state anti-bullying laws, and warrantless arrest laws aimed at curbing domestic violence. My first essay examines the causal relationship between athletic participation and means-tested program participation. I use the variation in the implementation of Title IX and find that a 30 percentage-point increase in female athletic participation induced by Title IX increased program participation among 25 to 40-year-old females by 2.8 percentage-points. This effect persists across SNAP, TANF, and Medicaid recipiency. Event study analysis and …

The Effect Of Deep-Water Multibeam Mapping Activity On The Foraging Behavior Of Cuvier’S Beaked Whales And The Marine Acoustic Environment, Hilary Suzanne Curran Kates Varghese

Doctoral Dissertations

Sound can propagate great distances underwater and is an important mode for marine life to obtain information. Human activities in the ocean such as global shipping, coastal construction, gas and oil exploration, and mapping navigation routes intentionally and unintentionally emit sound into the ocean, potentially interacting with marine life. Therefore, it is essential that the effects of anthropogenic noise on marine life and the ambient marine acoustic environment be understood. Most of the work, to date, has focused on the impact of low-frequency (<1 kHz) sources such as shipping noise, which is ubiquitous in the ocean, and mid-frequency (1-10 kHz) sources such as naval sonar, to which many marine mammals have shown to be sensitive. The effect of these sources can be as salient as a mass stranding event or as benign as an animal swimming away from a source of noise with no other effect. Less work has focused on higher frequency sources (>10 kHz), including ocean-mapping sonar systems. However, most marine mammals, namely toothed whales (odontocetes), are capable …

Investigation Of Anomalous Data Trends During Coal Dust Explosibilty Testing, Jacob Lee Miller

Doctoral Dissertations

Coal dust explosibility is a health and safety concern that has been a recognized hazard for over 100 years. Initial testing by the Author using a Siwek 20L apparatus recorded a secondary maximum pressure at higher dust concentrations (1,000-7,000g/m³) with Pulverized Pittsburgh Coal (PCC). Higher dust concentrations are beyond the typical ASTM E1226 testing procedure but are possible in mining and processing scenarios. No reference documents have been discovered that show a secondary maximum pressure at higher dust concentrations. Literature reviewed identified that once a coal dust concertation generates a peak pressure, the pressure remains constant or decreases …

Fabrication, Characterization Of High-Entropy Alloys And Deep Learning-Based Inspection In Metal Additive Manufacturing, Wenyuan Cui

Doctoral Dissertations

"Alloying has been used to confer desirable properties to materials. It typically involves the addition of small amounts of secondary elements to a primary element. In the past decade, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high- entropy alloys (HEAs) has been in vogue. In the first part, the investigation focused on the fabrication process and property assessment of the additive manufactured HEA to broaden its engineering applications. Additive manufacturing (AM) is based on manufacturing philosophy through the layer-by-layer method and accomplish the near net-shaped components …

Integrating Snp Data And Imputation Methods Into The Dna Methylation Analysis Framework, Yuqing Su

Doctoral Dissertations

"DNA methylation is a widely studied epigenetic modification that can influence the expression and regulation of functional genes, especially those related to aging, cancer and other diseases. The common goal of methylation studies is to find differences in methylation levels between samples collected under different conditions. Differences can be detected at the site level, but regulated methylation targets are most commonly clustered into short regions. Thus, identifying differentially methylated regions (DMRs) between different groups is of prime interest. Despite advanced technology that enables measuring methylation genome-wide, misinterpretations in the readings can arise due to the existence of single nucleotide polymorphisms …

Advanced Battery Modeling For Interfacial Phenomena And Optimal Charging, Yaqi Zhu

Doctoral Dissertations

"Lithium-ion batteries are one of the most promising energy storage systems for portable devices, transportation, and renewable grids. To meet the increasing requirements of these applications, higher energy density and areal capacity, long cycle life, fast charging rate and enhanced safety for lithium-ion battery (LIBs) are urgently needed. To solve these challenges, the relevant physics at different length scale need to be understood. However, experimental study is time consuming and limited in small scale’s study. Modeling techniques provide us powerful tools to get a deep understanding of the relevant physics and find optimal solutions. This work focuses on studying the …

Infrastructure Systems Modeling Using Data Visualization And Trend Extraction, Jacob Marshal Hale

Doctoral Dissertations

“Current infrastructure systems modeling literature lacks frameworks that integrate data visualization and trend extraction needed for complex systems decision making and planning. Critical infrastructures such as transportation and energy systems contain interdependencies that cannot be properly characterized without considering data visualization and trend extraction.

This dissertation presents two case analyses to showcase the effectiveness and improvements that can be made using these techniques. Case one examines flood management and mitigation of disruption impacts using geospatial characteristics as part of data visualization. Case two incorporates trend analysis and sustainability assessment into energy portfolio transitions.

Four distinct contributions are made in this …

Analysis Of The Primary Volatile Compositions In The Oort Cloud And Jupiter-Family Comets Towards The Goal Of Understanding Their Origin And Diversity, Mohammad Saki

Doctoral Dissertations

“Knowledge of the initial conditions present in the early solar nebula is required to understand the evolution and its current volatile content. Comets were some of the first objects to accrete in the solar nebula. They are among the most pristine (primitive) remnants of the solar system formation, and their present-day volatile composition likely reflects the composition and conditions where (and when) they formed. Therefore, they are fossils of the solar system formation. High-resolution near-infrared spectroscopy is a valuable tool for sampling the parent volatile (i.e., ices subliming directly from the nucleus) composition of comets via analysis of fluorescence emission …

Scaling, Experiments, And Simulations Of Condensation Heat Transfer For Advanced Nuclear Reactors Safety, Palash Kumar Bhowmik

Doctoral Dissertations

“The purpose of this research was to perform scaled experiments and simulations to validate computational fluid dynamics (CFD) and empirical models of condensation heat transfer (CHT) for the passive containment cooling system (PCCS) of Small Modular Reactors (SMRs). SMRs are the futuristic candidates for clean, economic, and safe energy generation; however, reactor licensing requires safety system evaluations, such as PCCS. The knowledge in the reviewed relevant literature showed a gap in experimental data for scaling SMR’s safety systems and validating computational models. The previously available test data were inconsistent due to unscaled geometric and varying physics conditions. These inconsistencies lead …

Source Reconstruction In Near Field Scanning For Rfi Application, Hosseien Rezaei

Doctoral Dissertations

"This research is divided into three major topics. The first topic, mechanical magnetic field generator for communication in the ULF range, is discussed in the first paper. The second topic, source reconstruction in near field scanning for RFI application, is discussed over the course of two papers. The third topic, analysis of imbalanced 2 or 3 Wire VHF LISN, is discussed in the last two papers.

In the first topic, the possibility to use a mechanical system (a rotating magnet) as a source (generator or antenna combined) of the ULF magnetic field is investigated. Ultralow frequency (ULF) communication systems have …

Investigating The Effect Of Operating Condition On Esd-Induced Soft-Failures, Omid Hoseini Izadi

Doctoral Dissertations

"Conflicting observations have been found in the literature regarding the effect of operating conditions on ESD (electrostatic discharge) susceptibility. While some studies have suggested a strong correlation between the two, others observed little to no correlation. In this work, a systematic study has been carried out suggesting the existence of a strong correlation between the ESD susceptibility and operating conditions. It is found that the root cause of this conflict is random ESD noise injection. A measurement approach is proposed to synchronize the noise injection with the system activity such as high/low CPU load. In this approach, the current consumption …

Integrated Solar And Ess Ac/Dc Systems For Various Grid Applications, Phani Ratna Vanamali Marthi

Doctoral Dissertations

"Modular multilevel converters (MMC) have gained prominence for high power applications in recent years due to their technical merits such as voltage scalability, harmonic performance, and high efficiency. Integration of renewable energy sources such as solar photovoltaic (PV) systems and energy storage systems (ESS) to the grid using power electronic (PE) resources is increasing due to the techno-economic successes achieved by such systems. Following these developments, the integration of MMCs with PV plants and ESS systems is one of the dynamic research avenues being pursued. Along these lines, an integrated development of PV plants, ESS, and alternating- and direct-current (ac/dc) …

Thermophysical Properties Of Nominally Phase Pure Boride Ceramics, Austin D. Stanfield

Doctoral Dissertations

"This research focusses on the thermophysical properties of nominally phase pure boride ceramics. As interest in ultra high temperature ceramics increases due to a renewed interest in hypersonic flight vehicles and with the expanding materials design space accompanying interest in high entropy materials, it is imperative to understand the intrinsic properties of boride ceramics. By reducing Hf content in ZrB₂ from the natural abundance, ~1.75 at% in this case, to ~100 ppm, thermal conductivity increased from 88 W/m·K to 141 W/m·K. Removal of Hf allowed the thermal conductivity of ZrB₂ with small transition metal solute additions to be …

Fiber Optic Sensors For Industry And Military Applications, Yiyang Zhuang

Doctoral Dissertations

"Fiber optic sensors (FOSs) have been widely used for measuring various physical and chemical measurands owing to their unique advantages over traditional sensors such as small size, high resolution, distributed sensing capabilities, and immunity to electromagnetic interference. This dissertation focuses on the development of robust FOSs with ultrahigh sensitivity and their applications in industry and military areas.

Firstly, novel fiber-optic extrinsic Fabry-Perot interferometer (EFPI) inclinometers for one- and two-dimensional tilt measurements with 20 nrad resolution were demonstrated. Compared to in-line fiber optic inclinometers, an extrinsic sensing motif was used in our prototype inclinometer. The variations in tilt angle of the …

Mining Haul Road Defect Detection -- Advancement In Automated Road Extent And Response Calibration For Improved Maintenance, Alexander David Douglas

Doctoral Dissertations

Mine haul roads degrade rapidly due to extremely heavy loads on sub optimal construction materials. This research tests two methods of defect detection to determine limitations to current technology: optical detection and vehicle vibration response. Optical defect detection was found to have the least significant limitations for surface defect detection and vehicle vibration response modeling has the least significant limitations for subsurface defects. This research proposes novel methods to eliminate the critical limitations of both technologies.

Unmanned Aerial Vehicles (UAV) equipped with GPS and a high-resolution camera is used to create a 3-D point cloud using a structure-from-motion algorithm. This …

Data And Resource Management In Wireless Networks Via Data Compression, Gps-Free Dissemination, And Learning, Xiaofei Cao

Doctoral Dissertations

“This research proposes several innovative approaches to collect data efficiently from large scale WSNs. First, a Z-compression algorithm has been proposed which exploits the temporal locality of the multi-dimensional sensing data and adapts the Z-order encoding algorithm to map multi-dimensional data to a one-dimensional data stream. The extended version of Z-compression adapts itself to working in low power WSNs running under low power listening (LPL) mode, and comprehensively analyzes its performance compressing both real-world and synthetic datasets. Second, it proposed an efficient geospatial based data collection scheme for IoTs that reduces redundant rebroadcast of up to 95% by only collecting …

Fiber-Optic And Coaxial-Cable Extrinsic Fabry-Perot Interferometers For Sensing Applications, Chen Zhu

Doctoral Dissertations

”The fiber-optic extrinsic Fabry-Perot interferometer (EFPI) is one of the simplest sensing configurations and is widely used in various applications due to its prominent features, such as high sensitivity, immunity to electromagnetic interference, and remote operation capability. In this research, a novel one-dimensional wide-range displacement sensor and a three-dimensional displacement sensor based on fiber-optic EFPIs are demonstrated. These two robust and easy-to-manufacture sensors expand the application scope of the fiber-optic EFPI sensor devices, and have great potential in structural health monitoring, the construction industry, oil well monitoring, and geo-technology.

Furthermore, inspired by the fiber-optic EFPI, a novel and universal ultra-sensitive …

3d-Printed Adsorbents For Gas Separations: A Material Development, Kinetic Assessment, And Process Performance Investigation, Shane Lawson

Doctoral Dissertations

“Adsorbent materials are promising for various gas purification processes, however, forming them into structured contactors is paramount in enhancing mass transfer properties and reducing pressure losses. In this research, various adsorbents were engineered into structured contactors with 3D printing. The overall goal of this research was to improve the formulation methods of 3D-printed adsorbents and understand their performances in gas separation processes. The specific objectives were to 1) develop new adsorbent 3D-printing strategies, 2) understand the kinetic properties of printed adsorbent monoliths, and 3) assess their process performances. Objective one was addressed by developing five 3D printing techniques: i) oxide …

Theoretical Study Of Magnetic Particles In A Shear Flow Subjected To A Uniform Magnetic Field, Christopher A. Sobecki

Doctoral Dissertations

"Magnetic manipulation of non-spherical magnetic microparticles is important for applications in shape-based and magnetic-based separations such as waste management, disease diagnostics, drug delivery, and mining. Manipulations of magnetic microparticles also include chain formation to assemble compositions for electronics, drug loading designs, and magnetorheological fluids for smart armor, hydraulic brakes, and dampers. In microfluidic devices, separation-formation-effectiveness depends on the shape of the channel, the shear rate, and the magnetic field strength and direction.

Particle separation and chain formation involved highly complex and computational expense-demanding studies in microfluidic devices, magnetic fields, and particle- particle/wall interactions. This research took complex experimental studies and …

Pdn Modeling For High-Speed Multilayer Pcb Boards And Decap Optimization Using Machine Learning Techniques, Ling Zhang

Doctoral Dissertations

"In power distribution networks (PDN), there are two main challenges nowadays. One challenge is how to efficiently model and calculate the impedance for arbitrary-shape and multi-layer PDN systems. The second challenge is the optimization of decoupling capacitors in the pre-layout stage. This dissertation proposes novel solutions to these two challenges. To tackle the first challenge, a boundary element method (BEM) is utilized to calculate the quasi-static inductances between vertical vias for arbitrary-shape planes. Then a specialized circuit solver is developed to solve the equivalent circuit of inductances and capacitances for multi-layer PDN structures. Also, a contour integral method (CIM) is …

Receiver Function Imaging Of The 410 And 660 Km Discontinuities And Seismic Azimuthal Anisotropy Revealed By Shear Wave Splitting Beneath The Australian Continent, Kailun Ba

Doctoral Dissertations

"The Australian continent is composed the of Precambrian cratons in the west and Phanerozolc orogens in the east. Despite numerous seismological studies, controversies remain regarding the structure, evolution, and dynamics of the crust and mantle beneath Australia. In this study, we used two techniques, receiver functions and shear wave splitting analyses, to investigate the topography of the mantle transition zone (MTZ) discontinuities and mantle seismic azimuthal anisotropy, respectively. We utilized P-to-S receiver functions to map the 410 and 660 km discontinuities bordering the MTZ. The discontinuity depths obtained show a systematic apparent uplifting for both discontinuities in central and western …