Digital Commons Network^™

Accelerating Graph Processing On Large-Scale Multicores, Masab Ahmad

Doctoral Dissertations

With the ever-increasing amount of data and input variations, portable performance is becoming harder to exploit on today’s architectures. Computational setups utilize single-chip processors, such as GPUs or large-scale multicores for graph analytics. Some algorithm-input combinations perform more efficiently when utilizing a GPU’s higher concurrency and bandwidth, while others perform better with a multicore’s stronger data caching capabilities. Architectural choices also occur within selected accelerators, where variables such as threading and thread placement need to be decided for optimal performance. This paper proposes a performance predictor paradigm for a heterogeneous parallel architecture where multiple disparate accelerators are integrated in an …

Stress Analysis Of Operating Gas Pipeline Installed By Horizontal Directional Drilling And Pullback Force Prediction During Installation, Hongfang Lu

Doctoral Dissertations

With the development of the natural gas industry, the demand for pipeline construction has also increased. In the context of advocating green construction, horizontal directional drilling (HDD), as one of the most widely utilized trenchless methods for pipeline installation, has received extensive attention in industry and academia in recent years. The safety of natural gas pipeline is very important in the process of construction and operation. It is necessary to conduct in-depth study on the safety of the pipeline installed by HDD method.

In this dissertation, motivated by the following considerations, two aspects of HDD are studied. First, through the …

Adaptive Feature Engineering Modeling For Ultrasound Image Classification For Decision Support, Hatwib Mugasa

Doctoral Dissertations

Ultrasonography is considered a relatively safe option for the diagnosis of benign and malignant cancer lesions due to the low-energy sound waves used. However, the visual interpretation of the ultrasound images is time-consuming and usually has high false alerts due to speckle noise. Improved methods of collection image-based data have been proposed to reduce noise in the images; however, this has proved not to solve the problem due to the complex nature of images and the exponential growth of biomedical datasets. Secondly, the target class in real-world biomedical datasets, that is the focus of interest of a biopsy, is usually …

Application Of Halloysite Nanotubes In Bone Disease Remediation And Bone Regeneration, Yangyang Luo

Doctoral Dissertations

Customized patient therapy has been a major research focus in recent years. There are two research fields that have made a significant contribution to realizing individualized-based treatment: targeted drug delivery and three-dimensional (3D) printing technology. With benefit from the advances in nanotechnology and biomaterial science, various drug delivery systems have been established to provide precise control of therapeutic agents release in time and space. The emergence of three-dimensional (3D) printing technology enables the fabrication of complicated structures that effectively mimic native tissues and makes it possible to print patient-specific implants. My dissertation research used a clay nanoparticle, halloysite, to develop …

Feature Space Modeling For Accurate And Efficient Learning From Non-Stationary Data, Ayesha Akter

Doctoral Dissertations

A non-stationary dataset is one whose statistical properties such as the mean, variance, correlation, probability distribution, etc. change over a specific interval of time. On the contrary, a stationary dataset is one whose statistical properties remain constant over time. Apart from the volatile statistical properties, non-stationary data poses other challenges such as time and memory management due to the limitation of computational resources mostly caused by the recent advancements in data collection technologies which generate a variety of data at an alarming pace and volume. Additionally, when the collected data is complex, managing data complexity, emerging from its dimensionality and …

Electrolytic Metallization Of Halloysite Nanotubes And Antimicrobial Applications, Ahmed Humayun

Doctoral Dissertations

Due to increased reports of infections and biofouling arising from the use of invasive medical devices, novel antimicrobial agents with suitable anti-biofouling properties are critically needed. Transition metals exhibit substantial antimicrobial activity; however, their use is limited because of their inherent toxicity to eukaryotic cells. In this regard, naturally occurring halloysite clay nanotubes (HNTs) show significant promise. HNTs possess a high surface area for adsorption while its hollow lumen can be used for loading different materials.

Herein, we demonstrate an electrolytic method for generating and depositing metal nanoparticles (NPs) on the HNTs outer surface and we propose an optimized method …

Dual Purpose Tunable Vibration Isolator Energy Harvester: Design, Fabrication, Modeling And Characterization, S. M. Mahdi Mofidian

Doctoral Dissertations

This dissertation is focused on design, fabrication, characterization, and modeling of a unique dual purpose vibration isolation energy harvesting system. The purpose of the system is to, simultaneously, attenuate unwanted vibrations and scavenge kinetic energy available in these vibrations. This study includes theoretical modeling and experimental work to fully characterize and understand the dynamic behavior of the fabricated dual purpose system. In the theoretical study, both numerical (Runge-Kutta) and analytical (Harmonic Balance Method, HBM) methods are used to obtain the dynamic behavior of the system. The system features a combination of mechanical and electromagnetic components to facilitate its dual functionality. …

A Multicarrier Technique For Monte Carlo Simulation Of Electrothermal Transport In Nanoelectronics, Tyler J. Spence

Doctoral Dissertations

The field of microelectronics plays an important role in many areas of engineering and science, being ubiquitous in aerospace, industrial manufacturing, biotechnology, and many other fields. Today, many micro- and nanoscale electronic devices are integrated into one package. e capacity to simulate new devices accurately is critical to the engineering design process, as device engineers use simulations to predict performance characteristics and identify potential issues before fabrication. A problem of particular interest is the simulation of devices which exhibit exotic behaviors due to non-equilibrium thermodynamics and thermal effects such as self-heating. Frequently, it is desirable to predict the level of …

Gully Erosion And Holocene-Anthropocene Environmental Change In Southern New England, Megan Hill

Doctoral Dissertations

The proposed Anthropocene epoch provides a novel framework for recognizing, measuring, and interpreting human impacts to landscapes around the world. Important also, is the need to place human impacts in the context of how these landscapes have been behaving over recent geologic time (i.e., the Late Pleistocene and Holocene). In southern New England, widespread Anthropocene landscape changes occurred throughout 17^th-20^th century following European settlement. Markers of these Anthropocene landscape changes are visible in high-resolution topographic data in the form of historic land use features (e.g., stone walls and charcoal hearths), in gullies that dissect hillslopes, and in …

Collective Behavior In Dissipative Systems: Flocking & Futbol, Maurici López-Felip

Doctoral Dissertations

Collective behavior and large-scale group dynamics have become especially hot topics of research in the physical, biological, and cognitive sciences — from microscopic interactions involving the signaling and collective response of bacteria, to the types of coordination dynamics that are present in team sports. Recent findings argue for a fundamental principle for the self-organization of activity that is indifferent to scale; and that the behavior manifest in both living and non-living collectives serves to satisfy the dissipation of energy and strives toward the maximization of entropy production. While undoubtedly provocative, this hypothesis opens up new avenues of inquiry for the …

The Impact Of Estradiol And Stress On Spatial Memory, Soniya Assudani Patel

Doctoral Dissertations

Spatial memory is a critical cognitive function that involves for navigating, interpreting, and representing environments, planning a route, remembering the location of an object or event, and understanding spatial configurations. The three studies presented are original investigations on how estradiol, anxiety, and stress influence hippocampal-dependent spatial memory. The first study assessed the impact of estradiol level on spatial memory in young adult women. Salivary assays were obtained to determine the exact estradiol level. Women at the high and low estradiol phases of their natural menstrual cycle were compared to each other and to women on oral contraceptives (OCs). Behavioral performance …

Development Of Reduced-Order Models For Engine Applications, Yunchao Wu

Doctoral Dissertations

Detailed chemical kinetics is critical for accurate prediction of complex flame behaviors, such as ignition and extinction in engine applications, but difficult to be applied in multi-dimensional flame simulations due to their large sizes. Reduced-order models are needed in such cases to enable high fidelity combustion simulations. This dissertation is focused on developing new model reduction strategies and reduced-order models for engine combustion applications. First, a linearized error propagation (LEP) method for skeletal mechanism reduction is proposed. LEP is based on Jacobian analysis of perfectly stirred reactors (PSR) and can more accurately predict the propagation of small reduction errors compared …

Microfluidic Systems For Cancer Diagnostics, Mohamed Sharafeldin

Doctoral Dissertations

Cancer is the second leading cause of death in noncommunicable diseases coming right after cardiovascular diseases. Early diagnosis is a key for improving survival expectancy and treatment outcomes as cancer in early stage is more responsive to treatment. Currently, center of diseases control and prevention (CDC) recommend regular screening for cervical, breast and colorectal cancers. Although other screening procedures are available for prostate, pancreatic, thyroid and ovarian cancer, they did not prove to be effective in reducing mortality rates of these cancers. Adaption of prostate specific antigen (PSA) screening test for prostate cancer has not been related to improved survival …

Characterization And Modeling Of Satellite-Based Precipitation Uncertainty Over Complex Terrain, Yagmur Derin

Doctoral Dissertations

The availability and quality of precipitation estimates is essential to the accuracy and reliability of hydrological modeling studies. Difficulties in the representation of high rainfall variability over mountainous areas using ground-based sensors make satellite-based precipitation products (SPPs) attractive for hydrological studies over such regions, since these products are quasi-global and available at high spatial resolution. Evaluation of several SPPs using rain gauge networks over ten mountainous regions across the globe has shown their performance is highly dependent on advancing the quality of primary data sources, one of which is passive microwave (PMW) retrievals. The evaluation of PMW retrievals is challenging, …

Whole Slide Imaging For High-Throughput Monitoring Of Microbial Growth And Its Application To Rapid Antimicrobial Susceptibility Testing, Donghui Song

Doctoral Dissertations

Archival abstract submitted

The Use Of A Targeted Omic Approach To Dissect The Nested Symbiosis Of The Eastern Subterranean Termite, Reticulitermes Flavipes, Michael Stephens

Doctoral Dissertations

Archival abstract submitted

Functional Nanomaterials For Energy And Sensor Applications, Dongwook Kwak

Doctoral Dissertations

Functional nanomaterials synthesized by a flame spray pyrolysis process called reactive spray deposition technology (RSDT) and a hydrothermal method along with drop-casting were investigated for energy and sensor applications in this dissertation. For a high temperature proton exchange membrane fuel cell (HT-PEMFC) application, RSDT was utilized to manufacture the nanostructured catalyst layer (CL). The study of the influence of binder content in the catalyst coated-membrane (CCM) was conducted in terms of optimization for the performance of HT-PEMFC. As sensor applications, two different types of detection technique are introduced: metal oxide-based resistor and surface acoustic wave (SAW) based detector. Especially, two …

Electrophysiological, Neural, And Perceptual Aspects Of Pitch, Karl D. Lerud

Doctoral Dissertations

Pitch is a perceptual rather than physical phenomenon, important for spoken language use, musical communication, and other aspects of everyday life. Auditory stimuli can be designed to probe the relationship between perception and physiological responses to pitch-evoking stimuli. One technique for measuring physiological responses to pitch-evoking stimuli is the frequency following response (FFR). The FFR is an electroencephalographic (EEG) response to periodic auditory stimuli. The FFR contains nonlinearities not present in the stimuli, including correlates of the amplitude envelope of the stimulus; however, these nonlinearities remain undercharacterized. The FFR is a composite response reflecting multiple neural and peripheral generators, and …

Relationship Between Dietary Furocoumarins And Melanoma Risk, Melissa Melough

Doctoral Dissertations

Furocoumarins are a class of photocarcinogenic and phototoxic compounds found naturally in numerous edible plants. Experimental evidence shows that when combined with UV radiation, furocoumarins may become photoactivated and induce DNA crosslinks, leading to DNA damage and carcinogenesis. Therefore, a link between dietary furocoumarins and melanoma has been proposed. This project aims to examine the relationship between dietary furocoumarins and melanoma risk through three specific aims. First, we examined the kinetics of dietary furocoumarins in healthy adults (Aim 1). As early as 15 minutes after consuming grapefruit, and for up to three or more hours after ingestion, furocoumarins were detectable …

Development Of A Raman Spectroscopic Method To Detect Protein Conformation In Amorphous Solids: Application To Protein Formulation And Stability, Lauren Kathleen Fontana

Doctoral Dissertations

Therapeutic proteins are freeze-dried to improve storage stability. However, any changes in conformation of the protein molecule induced by stresses encountered during freeze-drying can influence the storage stability. Fourier Transform Infrared spectroscopy (FTIR) is very useful for monitoring secondary structural changes in protein solid state, but is much less sensitive to smaller tertiary structural changes associated with tryptophan, tyrosine and phenylalanine residues, that may be more predictive of stability. The aim of the present study was development and evaluation of a solid-state Raman spectroscopic method capable of detecting both tertiary and secondary structural solid-state changes in the spectral region from …

Investigation Of The Bond Behavior Of Steel Reinforcement Bars Embedded In Ultra High Performance Concrete Under Static Loads Using Finite Element Modeling, Manish Roy

Doctoral Dissertations

The bond properties of reinforcement bars (rebar) embedded in concrete depends on the tensile behavior of the surrounding material and its capability of resisting micro cracks. Since the tensile behavior of Ultra High Performance Concrete (UHPC) is dominated by the amount and the orientation of fibers as well as the type of fibers, an effort has been made in this study to investigate the influence of the fiber volume fraction () and the fiber orientation on the bond behavior of steel rebar embedded in UHPC under a static loading condition using finite element simulation. Owing to the inclusion of discrete …

Cryptographic Solutions For Cyber-Physical System Security, Chenglu Jin

Doctoral Dissertations

Since the introduction of Stuxnet, security research of industrial control systems, or cyber-physical systems (CPSs) in general, has become a rapidly growing area. There is a widespread belief that solutions based on cryptographic primitives are generally considered too computationally expensive to realize security properties for CPS in practice.

In this dissertation, we will show how to efficiently leverage the limited computational power and storage on CPS devices to secure a CPS under the attacks initiated from sensors, controllers, and networks using cryptographic methods. More specifically, we will present an intrusion-tolerant and privacy-preserving sensor fusion scheme, a lightweight intrusion detection system …

Modeling And Finite Element Simulations Of Phase Change Memory Materials And Devices, Jake Scoggin

Doctoral Dissertations

I simulate phase change including stochastic nucleation and growth of discrete grains with a finite element framework which captures the latent heat of phase change and heterogeneous melting. I model the electrical conductivity, thermal conductivity, Seebeck coefficient, and specific heat in TiN, SiO₂, and the face centered cubic and amorphous phases of Ge₂Sb₂Te₅ as well as the thermal boundary conductance at interfaces of these materials over the temperatures and fields encountered during phase change memory device operation. Simulations show reset, set, and read of phase change memory devices including mushroom cells, encapsulated pillar …

Viral Community Assembly In Puerto Rican Bats, Anna Sjodin

Doctoral Dissertations

Viruses are the most abundant biological entity on Earth, yet little is known about the factors driving their abundance, frequency of occurrence, and distribution in non-human hosts. Most emerging infectious diseases of humans originate in wildlife, up to a quarter of which are caused by viruses, creating an urgent need to broaden understanding of viral systems. With its theoretical depth, ecology can provide mechanistic insights about viral diversity, with broad implications for public health and wildlife conservation. Unfortunately, few datasets exist that allow a thorough exploration of viral ecology, and the process of defining viral species can prohibit timely conclusions. …

Inequality Matters In Transitional China: The Hukou System, Class Structure, And Stratification Outcomes, Qiong (Miranda) Wu

Doctoral Dissertations

China has experienced a massive transformation over the past four decades. As China moves towards marketization and capitalism, scholars disagree over whether state or market mechanisms play a more prominent role in transitional China. The state-centered perspective emphasizes the continuing power of the socialist state in the transitional period, while the market-centered perspective highlights the rise of market forces in the capitalist economy. Building upon the market transition debate, this dissertation investigates the relative influence of state forces, which is represented by the longstanding hukou system, and market forces, which is represented by the emerging class structure in the determination …

Real-Time Neurotransmitter Monitoring Of Neuronal Networks In Epilepsy, Phillip Timothy Doughty

Doctoral Dissertations

Epilepsy affects almost 1% of the global population, and further study is necessary to reveal diagnostic biomarkers and therapeutic targets [1]. Second-by-second quantification of neurotransmitter molecules like L-glutamate is expected to elucidate the underlying mechanisms of epilepsy [2-4], and enzyme-based microelectrode probes offer improved temporal and spatial resolution over existing tools due to their smaller profiles and higher sampling frequencies [5, 6]. To that end, we tested a ceramic enzyme-based microelectrode array (MEA) probe in the hippocampi of Male Sprague-Dawley rats in vivo for the detection of L-glutamate during status epilepticus. Current induced by hydrogen peroxide, the reporter molecule resulting …

Organically Modified Inorganic Nanoparticles For Halochromic Ionophores And Nucleic Acids, William Johnston

Doctoral Dissertations

In this dissertation, four nanoparticle reaction schemes were developed as substrates for halochromic dyes or nucleic acids. The reaction schemes include the use of two substrates: silica nanoparticles and halloysite nanotubes. The protocols can incorporate silica (SiO2) nanoparticles and halloysite aluminosilicate (AlO2SiO2) nanotubes due to the presence of silane groups on the surface of either substrate. The reaction schemes are presented along with detailed protocols which were written to facilitate both reproducibility and to serve as an aid to further study and for easy modification of the protocol to suit a researcher's needs. The data is discussed in the materials …

Developing A Model Of Sexism-Based Traumatic Stress, Marcus Cherry

Doctoral Dissertations

In contemporary society, women regularly endure sexist microaggressions—messages that convey aversive, demeaning sexist slights toward women. Sexist microaggressions have been associated with anger, depression, anxiety, low self-esteem, job stress, increased risky health behavior and trauma. Additionally, sexist microaggressions effects are cumulative and can result in the internalization of sexist beliefs and undermine selfcompassion. Research suggests that these distortions of self-views and self-regard can in part contribute to the development of trauma symptoms. Notably, research has found that prolonged exposure to sexism, in general, has been associated with trauma symptoms. However, the traumatic effects of sexist microaggressions have remained largely theoretical. …

Design, Microfabrication And Characterization Of Concentric Gold Nanoring Electrode For Neurochemical Sensing, Haocheng Yin

Doctoral Dissertations

Nanoelectrodes have become widely used in electrochemical sensing in recent decades. When compared to microelectrodes, it has many unique advantages such as high signal to noise ratio, small sample volume requirement, and lower detection limits.

This work reports on the microfabrication and characterization of a gold nanoring electrode (Au NRE) patterned on top of a silicon (Si) micropillar. An NRE of 165  10 nm in width was micropatterned on 4.6  1 µm diameter  17.5  2.5 µm long Si micropillar with an intervening 50 nm thick hafnium oxide insulating layer. Scanning electron microscopy and energy dispersive spectroscopy …

Increasing The Functionality Of Additive Manufacturing Through Atmospheric Microplasma And Nanotechnology, Alexander Jon Ulrich

Doctoral Dissertations

Additive Manufacturing (AM) has been changing the manufacturing landscape for the last 20 years. As the interest and demand for both polymer and metal-based 3D printing has grown, the materials and machines used have increased in capabilities. Despite the growth and advancement, there are still a large number of improvements that can be made to add functionality to 3D printers. Metal AM, a subcategory of 3D printing, has garnered much attention among industrial applications with large companies such as General Electric trying to implement the technology to increase innovative designs for motors. Some of the limitations on AM have to …