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Microstructural Studies Of Ag/W And Ag3sn/Cu3sn Alloys For Electrical Circuit Breaker Contacts, Haibo Yu

Doctoral Dissertations

Contact materials composed of Ag and W have been used in circuit breakers and other electrical switching systems for decades due to their excellent properties. A series of standard acceptance tests have been established by UL (Underwriters Laboratories) to ensure that circuit breakers meet certain criteria for performance and safety. These standard tests include: overload/temperature-rise, endurance and short-circuit conditions. In this dissertation, a study on the near-surface microstructures exhibited by untested commercial Ag/W circuit breaker contacts, and by those that have been subjected to the UL standard tests, is presented. The microstructural characteristics were investigated to deduce the degradation mechanisms …

Multi-Level Dynamical Parameter Estimation: Hypothesis Testing With Dynamical Systems, Henry S. Harrison

Doctoral Dissertations

The practice of dynamical modeling of perception-action behavior has lagged behind the proliferation of the dynamical perspective. Two methodological roadblocks to dynamical modeling are discussed. First, parameter selection is difficult with current tools. Second, it is unclear what role models have in the larger scientific project beyond their use as descriptions or proofs of concept. In this dissertation, a new parameter selection method is developed to address these issues, Multi-Level Dynamical Parameter Estimation (MLDPE). Like its precursor DPE, MLDPE uses an extended Luenberger observer to stabilize the synchronization manifold in combined model-data space. MLDPE also embeds a regression model into …

Statistical Models For Single Molecule Localization Microscopy, Ahmed Elmokadem

Doctoral Dissertations

Single-molecule localization microscopy (SMLM) has revolutionized the field of cell biology. It allowed scientists to break the Abbe diffraction limit for fluorescence microscopy and got it closer to the electron microscopy resolution but still it faced some serious challenges. Two of the most important of these are the sample drift and the measurement noise problems that result in lower resolution images. Both of these problems are generally unavoidable where the sample drift is a natural mechanical phenomenon that occurs during the long time of image acquisition required for SMLM (Geisler et al. 2012) while the measurement noise, which arises from …

Design, Synthesis And Characterization Of Hydrophobic Polydivinylbenzene Adsorbent For Environmental Applications, Tahereh Jafari

Doctoral Dissertations

Archival abstract submitted

Design, Synthesis And Characterization Of Metal Oxide Adsorbents And Catalysts For Environmental Applications, Wei Zhong

Doctoral Dissertations

In this thesis, I will focus on the design and synthesis of metal oxides as adsorbents and catalysts for different types of environmental applications,such as water remediation, biogas cleanup. Controlled synthesis of these materials with unique crystalline structures, physical, and chemical properties will be carried out to achieve an improved performance. Correlations between the material property and performance will be investigated by varieties of characterization methods.

In the first part, I will employ perovskite materials for catalytic wet air oxidation (CWAO) reactions for water remediation. LaNiO_3-δ (LNO) was applied for degradation of methyl orange (MO) azo dye in aqueous …

Experimental Investigation On The Effects Of Free Stream Turbulence And Fuel Type On Structure And Blowoff Characteristics Of Turbulent Premixed Bluff-Body Stabilized Flames, Bikram Roy Chowdhury

Doctoral Dissertations

An experimental investigation on the effect of different levels of turbulence intensity and properties of the fuel/air mixture on the structure and characteristics of lean flames stabilized on an axisymmetric bluff body is described in this thesis. Simultaneous imaging of hydroxyl (OH) and formaldehyde (CH₂O) by planar laser induced fluorescence and particle image velocimetry (PIV) were used to study the interaction between the flame and the flow field. CH₂O fluorescence and the pixel-by-pixel multiplication of OH and CH₂O fluorescence signals were utilized to mark preheat and heat release regions respectively. In addition, high-speed chemiluminescence …

Architectural Primitives For Secure Computation Platforms, Syed Kamran Haider

Doctoral Dissertations

Computation outsourcing to a cloud cluster has become a common practice in today’s world. Unlike traditional computing models, the cloud computing model has raised serious challenges in terms of privacy and integrity of the users’ sensitive data. Depending on their respective adversarial models, modern secure processor architectures offer a promising solution to many of these challenges. However, almost all secure processor proposals dealing with computation outsourcing face two crucial security vulnerabilities that are still treated as open problems; the threat of hardware Trojans embedded inside the secure processor chip, and, the threat of privacy leakage via access patterns of the …

Computational Design Of Multifunctional Nanodielectrics, John Mangeri

Doctoral Dissertations

In this dissertation, a mesoscale modeling approach is developed aimed at simulating the properties of dielectric nano/microstructures with coupled polar, elastic, and thermal degrees of freedom, as well as the dependence of these properties on the structure size, shape, morphology and applied conditions. The versatility of this computational method to predict functional behavior is exemplified in the following systems: (i) Semiconducting core-shell nanoparticles and the influence of their size, anisotropy, microstructure and applied pressure on their optical properties; (ii) Ferroelectric nanoparticles embedded in a dielectric medium, and the dependence on their polarization-field topology and transitions on particle shape and size, …

Development Of Radar Absorbing Materials (Rams) Based On Nano-Structured Magnetic Materials And Applications, Ahmet Teber

Doctoral Dissertations

There has been a long-standing interest in the development of radar absorbing materials (RAMs) for military applications such as microwave absorbers for stealth technology, anechoic chambers, and morphing scenarios, as well as camouflaging ground-based hardware against airborne radar observation. Even so, there remain outstanding challenges in this area such as the selection of suitable material compositions, the available frequency bandwidth, and the required thickness of the materials. The properties of materials at the nano-scale can change significantly. With only a reduction in size (no change in the substance itself), materials can exhibit new properties such as electrical conductivity, insulating behavior, …

A Materials Genome Approach To The Design, Synthesis, And Testing Of High Energy Density Dielectric Materials For Capacitor Applications, Gregory Treich

Doctoral Dissertations

The rapid implementation and improvement of renewable energy technologies require advanced dielectric materials to enable capacitive energy storage under high fields. Since capacitors are among the most pervasive electronic device in many of these systems, my search for improved dielectrics focused on the application of film capacitors. To overcome these current problems, new polymers need to be developed that can serve as the dielectric material in electronic devices. Such a comprehensive search requires careful prior planning to ensure that effort is not needlessly wasted and thus a rational co-design approach was developed. Through this approach, high-throughput computational predictions are used …

Point Cloud Model Shape Analysis, Reed Williams

Doctoral Dissertations

Shape analysis of point cloud surface models produces quality results and avoids the pitfalls of working with mesh models.

Shape analysis is concerned with understanding the shape of models geometrically, topologically, and relationally. Traditionally, shape analysis methods have operated on solid and surface models of objects, especially surface mesh models.

Recent advances in 3D camera technology has driven demand for automatic shape analysis tools.

Devices like the Microsoft Kinect are democratizing 3D sensing and such expansion of what was once an academic and industrial space is making it clear that there is a need for generally-applicable techniques which don't require …

Advancing Our Understanding Of Performance During Sleep Deprivation, Jeffrey Blake Bolkhovsky

Doctoral Dissertations

Sleep deprivation is a concern in professional, military, and personal settings and can potentially lead to critical, life threatening errors. Predicting a person’s behavior under the effects of sleep deprivation allows for the mitigation of risk due to reduced performance. The objectives of this dissertation are 1) to examine the role of sleep deprivation on cognitive and motor performance with the goal of contributing to a predictive model of complex real-world tasks, and 2) to explore non-invasive and non-disruptive physiological correlates of sleep deprivation through eye-tracking. Currently lacking in literature, and consequently from predictive models, are the generalized effects that …

An Accuracy Study Of Rtk Gnss Positioning Applied To Comparing Maps For Bentgrass Habitat Modeling, Jinwon Chung

Doctoral Dissertations

Theory and previous research suggest that sky obstructions and humidity can degrade global navigation satellite system (GNSS) positioning accuracy for static observation sessions. It is reasonable to suppose that these effects might be even worse for real-time kinematic (RTK) positioning, because the observer will likely collect fewer observations for RTK positioning than for a static occupation, so the statistics used to estimate the positions have fewer data to work with. These effects have not been thoroughly studied, which provided the motivation to conduct several experiments to quantity the effects. Temperature and humidity are variables of interest, so the first experiment …

Development And Application Of Advanced Econometric Models For Exploring Activity-Travel Behavior, Annesha Enam

Doctoral Dissertations

Historically, transportation planning relied on aggregate, trip-based procedures, namely, four-step modeling, for modeling travel demand. The aggregate approaches served well when the capacity oriented policies were of primary interest. However, in the last few decades, with the growing demand for travel and the increasing externalities (e.g. congestion, energy implications, pollution), there is a widespread acknowledgement that capacity oriented approach to transportation planning is unsustainable. Instead, the focus of the transportation planners has shifted towards sustainable demand management strategies wherein the idea is to alter existing behaviors and promote new behaviors such that demand for travel can be met while also …

Riparian Impacts To Stream Water Quality Across Spatial Scales, David J. Rosa

Doctoral Dissertations

This research contributes new knowledge to two major challenges: 1) up-scaling water quality results from riparian treatment plots to larger watersheds and 2) determining if a short-rotation woody crop (SRWC) can be an effective riparian buffer for treating agricultural nonpoint source pollution. An exhaustive literature review was conducted to provide detailed insight into the methods of scaling, the associated mathematical equations, and their application to the problem of predicting water quality. Dimensional analysis was identified as an underutilized but promising technique for water quality scaling. Dimensional analysis was used to predict total phosphorus (TP) concentrations across heterogenous watersheds ranging from …

Electronic Structure And Vibrational Behavior Of Polyethylene: Role Of Chemical, Morphological And Interfacial Complexity, Lihua Chen

Doctoral Dissertations

Archival abstract submitted

A Cross-Layer Resilient Multicore Architecture, Qingchuan Shi

Doctoral Dissertations

The ever-increasing miniaturization of semiconductors has led to important advances in mobile, cloud and network computing. However, it has caused electronic devices to become less reliable and microprocessors more susceptible to transient faults induced by radiations. These intermittent faults do not provoke permanent damage, but may result in incorrect execution of programs by altering signal transfers or stored values. These transitory faults are also called soft errors. As technology scales, researchers and industry pundits are projecting that soft-error problems will become increasingly important. Today’s processors implement multicores, featuring diverse set of compute cores and on-board memory sub-systems connected via networks-on-chip …

Structural Health Monitoring Of Buildings For Safety Assessments Under Explosions, Edward Eskew

Doctoral Dissertations

Due to unstable political climates across the world, the potential for terrorist attacks against civil infrastructure has become a serious concern. The increasing threat of explosions has fueled the need for research into methods to rapidly, and safely, assess the condition and safety of a structure from a blast. The ability to assess the structures safety from a potential blast with cumulative structural damage can be used to update security operations or retro-fit elements to improve resilience. In this work, structural health monitoring is used to determine the safety of structures before and the condition after a blast event, incorporating …

Project Recess: Restructuring Environmental Contingencies And Enhancing Self-Managed Supervision, Laura Kern

Doctoral Dissertations

Aggressive behaviors are garnering a great deal of national attention in research, policy, and practice circles. The majority of these problematic behaviors occur in non-classroom settings, where students outnumber staff and structure is lacking. Although strategies, like active supervision, are effective at reducing problem behavior in these settings, adults often miss opportunities to implement these strategies to achieve desired results. Project RECESS (Restructuring Environmental Contingencies and Enhancing Self-Managed Supervision) introduces a behavioral approach to increase adult active supervision through the use of self-management. Specifically, four recess supervisors participated in a brief training on active supervision and engaged in self-management by …

Computer Aided Design Solutions For Testability And Security, Qihang Shi

Doctoral Dissertations

As technology down scaling continues, new technical challenges emerge for the Integrated Circuits (IC) industry. One direct impact of down-scaling in feature sizes leads to elevated process variations, which has been complicating timing closure and requiring classification of fabricated ICs according to their maximum performance. To address this challenge, speed-binning based on on-chip delay sensor measurements has been proposed as alternative to current speed-binning methods. This practice requires advanced data analysis techniques for the binning result to be accurate. Down-scaling has also increased transistor count, which puts an increased burden on IC testing. In particular, increase in area and capacity …

The Margination And Transport Of Particles In Blood Flow, Erik James Carboni

Doctoral Dissertations

Archival abstract submitted.

Dielectric And Electrothermal Properties Of Ferroelectric Multilayers And Superlattice Heterostructures, Mehmet Kesim

Doctoral Dissertations

Artificial ferroelectric (FE) heterostructures show unique electrical properties compared to bulk and single-crystal and thin film FEs. The internal built-in electrical fields due to heterogenoeuos nature of the structure gives rise to unique electrical properties. Dielectric and electrothermal (pyroelectric and electrocaloric) properties of such multilayers and superlattice (SL) heterostructures are investigated using a non-linear thermodynamic model. The underlying reasons for the enhancement of electrical properties of FE heterostructures are analyzed based on the strain and built-in electrostatic fields that could be used as design parameters under realistic processing conditions of such materials. It is shown that the choice of multilayer/substrate …

Statistical Methods For Information Assessment And Data Compatibility With Applications, Daoyuan Shi

Doctoral Dissertations

Various modifications have been suggested in the past to extend the Shannon entropy to continuous random variables. We propose a new entropy called the fractional size adjusted entropy and later extend it to the generalized fractional size adjusted entropy. These two proposed entropies always exist and maintain non-negative values. The generalized fractional size adjusted entropy also includes many well-known entropies as its special cases, such as the Shannon entropy and the Renyi entropy. We apply our proposed entropies on various distributions and a phylogenetic example to demonstrate their good performances.

In addition, we propose a partition based measure to quantify …

Ultra-Low Chloride Content Water Production For Corrosion Control, Lewis Crone

Doctoral Dissertations

A process was developed to produce ultra-low chloride content on the industry standard strongly basic, gel -type anion resin employed in an equivalent mixture with companion cation resin in the deep bed condensate polishers at Dominion’s Millstone Power Station. The low chloride anion facilitated on-line conversion of the polisher resins to the amine chemical form, enabling an increase in secondary cycle amine concentration and pH for the purpose of minimizing general and erosion corrosion. This dissertation describes the research, testing, and full scale implementation of this unique application of ion exchange resins that led to an eighty percent reduction in …

Investigation And Mitigation Of Anode And Cathode Impurities To Improve Polymer Electrolyte Fuel Cell Performance, Mehmet Ozan Ozdemir

Doctoral Dissertations

Due to an increasing demand for environment-friendly power production, polymer electrolyte fuel cells (PEFCs) are promising devices with their low operation temperature, zero-emission, high efficiency and smaller sizes. However, some challenges still exist in commercial applications. One of the issues is impurities in hydrogen (anode fuel) and air (cathode oxidant).

The first objective of this thesis is to investigate the carbon monoxide (CO) poisoning and a mitigation method of high-level CO (1,000 and 10,000 ppm) in a platinum (Pt) catalyst layer using hydrogen (H₂)/CO mixture as the inlet fuel. A one-dimensional transient model is developed including the species …

Novel Methods To Address Measurement Error Issues In Gifted Identification, Huihui Yu

Doctoral Dissertations

This study applied statistical simulation techniques to posit a practical situation of gifted identification based on students’ performance on the intelligence test and academic achievement tests of math and reading. Three tests were generated based on the one-parameter item response theory model. The marginal reliabilities were .95, .90, and .80 for observed intelligence and observed abilities in math and reading, respectively. Totally, 1,000,000 pairs of true and observed abilities in each of the three domain areas were generated. Results suggest that using different combination rules is conceptually aimed to identify different gifted populations. Using the conjunctive rule to combine a …

Rating Game – Inflation Detection, Audit Design, And Technology Adoption On The Nursing Home Compare System, Xu Han

Doctoral Dissertations

The Nursing Home Compare System supported by the Centers for Medicare & Medicaid Services (CMS) is being widely used by patients, medical providers and payers. However, evidence suggests that the rating system is prone to self-reporting inflation, leading to biased and misleading ratings. This dissertation consists of three essays analyzing a series of issues that arise in this rating system, including inflation detection, performance evaluation, audit design, and technology adoption.

In the first essay, we use data over 2009-2013 for 1219 California nursing homes to empirically examine the key factors affecting a nursing home’s rating. We find a significant association …

Design And Architecture Of Hardware-Based Random Function Security Primitives, Fatemeh Tehranipoor

Doctoral Dissertations

In recent years, security has grown into a critical issue in modern information systems. Electronic hardware security, in particular, has emerged as one of the most serious challenges due to electronic devices penetrating every aspect of our society. Furthermore, due to the trend in globalization, system integrators have had to deal with integrated circuit (IC)/intellectual property (IP) counterfeiting more than ever. These counterfeit hardware issues counterfeit hardware that have driven the need for more secure chip authentication, since traditional ID or key storage have been demonstrated to be vulnerable to various kinds of attacks. In addition, due to the need …

Neural Coding And Models For Natural Sounds Recognition: Effects Of Temporal And Spectral Features, Seyedeh Fatemeh Khatami Firoozabadi

Doctoral Dissertations

The mammalian brain is able to recognize natural sounds in the presence of acoustic uncertainties such as background noise. A prevailing theory of neural coding suggest that neural systems are optimized for natural environment signals and sensory inputs that are biologically relevant. The optimal coding hypothesis thus suggests that neural populations should encode sensory information so as to maximize efficient utilization of environmental inputs. In the first part of my thesis, I will explore the origins of scale invariance phenomena which has been previously described for natural sounds and has been observed in a variety of natural sensory signals including …

A Configurable Framework For Rbac, Mac, And Dac For Mobile Applications, Yaira Karine Rivera Sánchez

Doctoral Dissertations

In the last decade, mobile computing as evidenced by the emergence of mobile devices (smartphones, phablets, tablets) has dominated personal and business computing. Users of traditional computing devices (e.g., PCs, laptops, etc.) are transitioning to mobile devices to perform daily tasks such as managing emails, playing games, viewing/editing documents, paying bills, managing healthcare data, etc. The majority of these tasks can be performed through the means of mobile applications, which is a piece of software specifically made to run on a mobile device. Mobile applications (apps) can contain data that ranges from being non-sensitive to highly-sensitive. Specifically, for those apps …