Digital Commons Network^™

Security Against Data Falsification Attacks In Smart City Applications, Venkata Praveen Kumar Madhavarapu

Doctoral Dissertations

Smart city applications like smart grid, smart transportation, healthcare deal with very important data collected from IoT devices. False reporting of data consumption from device failures or by organized adversaries may have drastic consequences on the quality of operations. To deal with this, we propose a coarse grained and a fine grained anomaly based security event detection technique that uses indicators such as deviation and directional change in the time series of the proposed anomaly detection metrics to detect different attacks. We also built a trust scoring metric to filter out the malicious devices. Another challenging problem is injection of …

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 …

Critical Behavior In Evolutionary And Population Dynamics, Stephen Walter Ordway

Doctoral Dissertations

“This study is an exploration of phase transition behavior in evolutionary and population dynamics, and techniques for predicting population changes, across the disciplines of physics, biology, and computer science. Under the looming threat of climate change, it is imperative to understand the dynamics of populations under environmental stress and to identify early warning signals of population decline. These issues are explored here in (1) a computational model of evolutionary dynamics, (2) an experimental system of decaying populations under environmental stress, and (3) a machine learning approach to predict population changes based on environmental factors. Through the lens of critical phase …

Robustness Against Attacks And Uncertainties In Smart Cyber-Physical Systems, Prithwiraj Roy

Doctoral Dissertations

Cyber-Physical Systems (CPS) are sensing, processing, and communicating platforms, embedded with physical devices that provide real-time monitoring and control. Security challenges in CPS necessitate solutions that are robust against attacks and uncertainties and provide a seamless operation, especially when used in real-time applications to monitor and secure critical infrastructures. CPS mainly consists of a physical component for sensing or monitoring and a cyber component for processing and communicating. The quality of interactions between physical and cyber systems has direct impacts on the system’s performance and reliability.

CPS plays a major role in smart services and applications within a smart living …

Modeling For Off-Chip High-Speed Designs, Siqi Bai

Doctoral Dissertations

”Signal integrity (SI) and power integrity (PI) are essential for datacenter application. A typical datacenter rack consists of a switch on the top of the rack, servers, and storage units. Three SI/PI related problems for datacenter application are analyzed in this research.

The first topic is analysis on power via induced Quasi-quarter-wavelength resonance to reduce crosstalk. Using an analytical model and 3D full-wave simulation models, a physical explanation for the unexpected resonance in the differential signal pairs is proposed. Considering the difficulty in changing the pin map of the IC-package, several PCB layouts to eliminate the power via induced quasi-quarter-wavelength …

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 …

Designing Transition Metal Chalcogenides Electrocatalyst Surfaces For High-Efficiency Water Oxidation, Umanga De Silva

Doctoral Dissertations

”The rising demand for energy security and reducing fossil fuel dependence has prompted researchers to search for a clean, sustainable, and efficient energy generation system with low environmental impact. Water electrolysis has been identified as one of the most important processes satisfying the above needs to generate hydrogen as a clean fuel. Two half-cell reactions of oxygen evolution reaction (OER) at the anode and hydrogen evolution reaction (HER) at the cathode comprise the main process of water electrolysis. However, the oxygen evolution reaction is the most crucial step for efficient water splitting. Traditionally, metal oxides have been utilized as catalysts …

Secure Data Sharing In Cloud And Iot By Leveraging Attribute-Based Encryption And Blockchain, Md Azharul Islam

Doctoral Dissertations

“Data sharing is very important to enable different types of cloud and IoT-based services. For example, organizations migrate their data to the cloud and share it with employees and customers in order to enjoy better fault-tolerance, high-availability, and scalability offered by the cloud. Wearable devices such as smart watch share user’s activity, location, and health data (e.g., heart rate, ECG) with the service provider for smart analytic. However, data can be sensitive, and the cloud and IoT service providers cannot be fully trusted with maintaining the security, privacy, and confidentiality of the data. Hence, new schemes and protocols are required …

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 …

High Throughput Analysis To Study Emerging Pollutants And Nanoparticle Fate In Biological Systems, Xiaolong He

Doctoral Dissertations

”The increasing applications of emerging and fugitive contaminants (EFCs) and engineered nanoparticles (ENPs) attract significant research interest for their potential risks to human health and the environment. In order to assess the health risks of these emerging contaminants, rapid and reliable analytical methods to measure the concentrations and fates of these contaminants are imperative. This dissertation focuses on the developments of advanced analytical methods and their applications to study those emerging contaminants in crop plant and simulated gastric fluid (SGF). Three types of mass spectrometry based methodologies have been developed, one is freeze-thaw/centrifugation extraction followed by high performance liquid chromatography …

Advanced Control Techniques For Modern Inertia Based Inverters, Sepehr Saadatman

Doctoral Dissertations

”In this research three artificial intelligent (AI)-based techniques are proposed to regulate the voltage and frequency of a grid-connected inverter. The increase in the penetration of renewable energy sources (RESs) into the power grid has led to the increase in the penetration of fast-responding inertia-less power converters. The increase in the penetration of these power electronics converters changes the nature of the conventional grid, in which the existing kinetic inertia in the rotating parts of the enormous generators plays a vital role. The concept of virtual inertia control scheme is proposed to make the behavior of grid connected inverters more …

Prediction Of Deflection Of Helical Anchors Under Load, Andre Stephen Hawks

Doctoral Dissertations

”As the sophistication of modern structural design methods has improved over time, the ability to accurately predict and model foundation stiffness has become increasingly more important. In complicated structural systems with deep foundations, correct calculation of the distribution of load and serviceability requires proper modeling of axial load-deflection characteristics. To keep pace with advances in structural analysis, there is much need for more practical and scientific work on the load-deflection prediction of deep foundations including Helical Anchors.

The load-settlement mechanism of an axially loaded helical pile is a complex soil-structure interaction problem influenced by helical pile dimensions, installation method, and …

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 …

Additively Manufactured Metallic Cellular Structures, Okanmisope Aziel Fashanu

Doctoral Dissertations

"Cellular structures are lightweight structures with excellent mechanical, thermal, and acoustic properties. They offer promise in a series of applications, including lightweight applications, sandwich cores, mechanical damping, acoustic absorption, strain isolation, and thermal management. The manufacturing of these complex cellular structures is expensive and time-consuming, which hinders the adoption of these structures in many industries. Advancement in manufacturing technologies, such as additive manufacturing (AM), however, have changed this. AM allows for the rapid and less expensive manufacturing of complex cellular structures. This work aimed to investigate the performance of additively manufactured cellular structures for lightweight and sandwich core applications. In …

Identification Of Neuromarkers Using Structural And Functional Neuroimaging, Sreevalsan Sanathanan Menon

Doctoral Dissertations

"One of the grand challenges in science is understanding the human brain. Recent advances in magnetic resonance imaging have opened unmatched opportunities to demystify neural circuitry. In this research, the spatially and temporally complex neuroimaging data were used to identify neuromarkers that aids in quantifying a brain’s health. In the first part, a comparison of static and dynamic functional connectivities was made to study their efficacies in identifying intrinsic individual connectivity patterns. Results show that the intrinsic individual connectivity pattern can be used as a ‘fingerprint’ to distinguish among and identify subjects and their biological sex and is more accurately …

Novel Synthetic Methods And Applications Of Porous Materials: Aerogel Foams, Metallic Aerogels, Amorphous And Graphitic Carbon Aerogels, Rushi Soni

Doctoral Dissertations

"We report novel methods for the synthesis of porous materials such as polymeric aerogel foams, pure metallic aerogels, amorphous and graphitic carbon aerogels, and their applications. I. Polyurethane based aerogel foams were synthesized with an aliphatic triisocyanate and ethylene glycol through a pressurized (7 bar) sol-gel method. The foam-like structure is prepared without any chemical foaming agents or templates, resulting in less expensive, more efficient, readily adaptable, and environmentally friendly process. Those materials exhibited lower thermal conductivity (by 25%) and higher oil adsorption capacity (by 36% w/w) than their corresponding aerogels. II. Monolithic, pure metallic Co(0) aerogels were synthesized from …

Teaching Critical Thinking Skills In A Chinese Immersion School, Pui Hung Helen Wong

Doctoral Dissertations

As a frontline teacher and administrator, I received feedback consistently from parents and students asking for a fun and effective method of instruction for Chinese language development in the US. This study explored the micro-level of how teachers in Chinese immersion schools create an environment to support development of students’ critical thinking skills while learning Chinese. I applied a qualitative approach to the research and designed a case study focused on answering the following research questions: How do teachers help their students to develop critical thinking skills when teaching in a Chinese immersion program? What are the challenges teachers have …

Analysis Of The Population Dynamics Of Placida Dendritica And Codium Fragile In The Gulf Of Maine And A Theoretical Discussion Of Invasive Species, Seth Goodnight

Doctoral Dissertations

This dissertation examines several aspects of the biology and ecology of Codium fragile and Placida dendritica in the Gulf of Maine. Scientific interest in nonindigenous species was examined to determine if any patterns were evident that might indicate a change in the status of an invasive species. Interest in C. fragile had waned in recent years, the timing of which coincides with the decreased ecological dominance and apparent naturalization of the alga. Laboratory and field studies were combined to quantify the dynamics in the population of C. fragile and in the recruitment dynamics of P. dendritica. Results of laboratory research …

Characterizing Student Engagement In A Post-Secondary Developmental Mathematics Class And Exploring The Reflexivity Between Social And Sociomathematical Norms, David Fifty

Doctoral Dissertations

Traditionally, post-secondary developmental mathematics courses aspire to equip students with mathematical content knowledge needed to succeed in calculus and subsequent STEM courses. The literature shows that this goal alone is insufficient, as the emphasis on content acquisition often comes at the expense of developing higher-order skills such as argumentation, reasoning, and flexibility in mathematics problem solving (Chiaravalloti, 2009; Partanen & Kaasila, 2014; Star et al., 2015). Redesigning curricula with these additional objectives in mind requires providing students with opportunities to engage with mathematics in ways that may contrast with their past experiences or expectations. It requires changing patterns of classroom …

Magnetoelastic Excitations In Chiral Magnets, Christopher Libby

Doctoral Dissertations

Emergence of quasiparticles is a central concept in condensed matter physics. As an example, in solids, lattice vibrations lead to quantized phonon excitations, which gives rise to many exotic phenomena, including superconductivity. Things become richer in magnetic systems. Collective fluctuations about a magnetic ground state induce the spin wave excitation, whose quantized quasiparticle is dubbed as the magnon. A fundamental question is how phonon and magnon, as two separate degrees of freedom, can be coupled together. More importantly, certain symmetry, such as spatial inversion symmetry, can be broken in novel magnetic textures. It is interesting to explore whether broken symmetry …

A Meta-Analysis Of Gender Gap On The Fci In High School And College Introductory Physics Courses In The Us And International Countries., Polin Yadak

Doctoral Dissertations

This meta-analysis synthesized research on gender gap in the Force Concept Inventory (FCI). The main goal of the present meta-analysis was to identify the moderator variables that mediate effect size differences. Furthermore, the statistical significance of the average effect sizes was investigated. The inclusion criteria for the meta-analysis resulted in 22 empirical research articles that studied gender gap and reported the number of male and female students in the study. The included articles reported multiple studies; therefore, there were 34 studies on pretest and 43 studies on the posttest FCI. The average effect size for the pretests was 0.62 and …

An Analysis Of The Yearly Dynamic Change Relationship Between Working Memory Ability And Mathematics Achievement Of K-5 Students Using The Grimm Et Al. (2012) Extensions Of The Multivariate Latent Difference Score Models, Wenyan (Emma) Jiang Erzincanli

Doctoral Dissertations

The purpose of this study was to conduct a secondary data analysis to examine the dynamic change relationship between working memory and mathematics over time, and to address the working memory training program issue by examining this dynamic change relationship across four different groups of students to provide evidence on how to help different types of students improve their mathematics achievement. To achieve this purpose, the ECLS-K:2011 longitudinal data set and Grimm, An, McArdle, Zonderman, and Resnick (2012) extension of the multivariate latent difference score models were used for the secondary data analysis. Working memory ability and mathematics achievement were …

The Natural Potential Of Transition Metals To Activate The Initial Steps Of Fischer-Tropsch Catalysis: A Dft Study, Sumegha Godara

Doctoral Dissertations

With recent advances in modeling and simulations methods along with state-of-the- art supercomputers, theoretical studies are becoming a cheaper choice for scientific predictions and provide complementary support to the experiments. Intense research in catalysis has been done in the past two decades experimentally as well as theoretically. This works employs first-principle studies to predict the most promising catalysts for Fischer-Tropsch (FT) reaction based on size and composition. The transition metals Fe, Co, Ni, Ru, Pd, and Pt, have been explored in pure and alloyed nanocluster forms for the effectiveness of catalytic properties.

The first and most crucial step of the …

Stochastic Decision Modeling To Improve Breast Cancer Preventive Care, Sevda Molani

Doctoral Dissertations

Breast cancer is a leading cause of premature mortality among women in the United States. Breast cancer screening tests can help with detecting breast cancer in early stages and thereby reducing the breast cancer mortality risk. However, due to the imperfect nature of screening tests, there is always some associated overdiagnosis, false positives, and false negatives risks. Therefore, to improve breast cancer preventive care, we defined the focus of this dissertation on modeling breast cancer screening decisions.

Breast cancer overdiagnosis is the first issue that is addressed in this dissertation. Although overdiagnosis is known to be the major risk inherent …

The Natural Potential Of Transition Metals To Activate The Initial Steps Of Fischer-Tropsch Catalysis: A Dft Study, Sumegha Godara

Doctoral Dissertations

With recent advances in modeling and simulations methods along with state-of-the- art supercomputers, theoretical studies are becoming a cheaper choice for scientific predictions and provide complementary support to the experiments. Intense research in catalysis has been done in the past two decades experimentally as well as theoretically. This works employs first-principle studies to predict the most promising catalysts for Fischer-Tropsch (FT) reaction based on size and composition. The transition metals Fe, Co, Ni, Ru, Pd, and Pt, have been explored in pure and alloyed nanocluster forms for the effectiveness of catalytic properties.

The first and most crucial step of the …

A Qualitative Analysis Of The Effects Of Corequisite Developmental Educational Reform Upon Community College Finances, Casey L. Martin

Doctoral Dissertations

The purpose of this research study was to investigate how a community college’s finances were affected by an organizational change. For this study, the organizational change was the implementation of corequisite developmental education reform. This study used a qualitative research method to collect and analyze data to answer the following research question: How were a community college’s finances impacted when a corequisite developmental, educational reform was implemented? The literature review presented an analysis of different states’ legislation requiring developmental education reform, which included an in-depth review of cases involving institutions from within those states that have implemented corequisite programs according …

Zinc Oxide Based Nanowire Arrays For Selective Detection Of Multiple Gaseous Analytes At Elevated Temperature, Bo Zhang

Doctoral Dissertations

Zinc oxide (ZnO) based nanostructures represent an important class of gas sensor materials, due to their high surface-to-volume ratio, significant surface band structure bending upon gaseous analyte exposures, good mobility of charge carriers, and good structural stability at elevated temperature. Their usually surface-dominant sensing processes entail the important roles played by nanostructure size, defects, morphologies, and surface absorbate energetics and dynamics. In this dissertation, based on ZnO nanowire array as a gas sensing platform, rational decoration of electronic sensitizers, such as Au nanoparticles, and semiconducting oxide, such as Fe₂O₃ nanoparticles, has been employed to boost its electrical …

Distributed Cooperative Control Of Multi-Agent Systems Under Detectability And Communication Constraints, Himadri Basu

Doctoral Dissertations

Cooperative control of multi-agent systems has recently gained widespread attention from the scientific communities due to numerous applications in areas such as the formation control in unmanned vehicles, cooperative attitude control of spacecrafts, clustering of micro-satellites, environmental monitoring and exploration by mobile sensor networks, etc. The primary goal of a cooperative control problem for multi-agent systems is to design a decentralized control algorithm for each agent, relying on the local coordination of their actions to exhibit a collective behavior. Common challenges encountered in the study of cooperative control problems are unavailable group-level information, and limited bandwidth of the shared communication. …

Reducing Dropout Rates Of New Hampshire High School Students By Increasing The Compelled Years Of Attendance: An Analysis Of Local Administrator Perceptions Of And Responses To State Law 193:1, Andrew K. Korman

Doctoral Dissertations

In 2007 New Hampshire passed a law, RSA 193:1, that changed the compulsory age of education for all public school students from age 16 to age 18. The purpose of this research is to explore the effect of RSA 193:1 on dropout rates in New Hampshire’s public high schools and to examine the perception of the high school principal in understanding the effect of the law and any differential effects of the law on students. Through an examination of five years of dropout data combined with a survey to current high school principals, findings indicate that there is strong support …

Experiments And Modeling Of Plastic Anisotropy And Ductile Fracture Under Multiaxial Loading, Madhav Baral

Doctoral Dissertations

The implementation of new materials for light-weighting purposes in the automotive industry has often been hindered due to the low ductility of these materials, as well as inadequate empirical knowledge about their fracture behavior and inadequate material modeling techniques. This thesis addresses these issues through extensive experimental and numerical study of plastic anisotropy and ductile fracture of several aluminum alloys and a stainless-steel. The test materials used for this study include AA365 die-casting, AA6013 and AA6111 aluminum sheets, AA6260 aluminum tube and SS304L stainless-steel microtube. The plastic anisotropy is assessed using uniaxial tension, plane-strain tension and disc compression experiments for …