Digital Commons Network^™

Topology Dependence Of Ppm-Based Internet Protocol Traceback Schemes, Ankunda R. Kiremire

Doctoral Dissertations

Multiple schemes that utilize probabilistic packet marking (PPM) have been proposed to deal with Distributed Denial of Service (DDoS) attacks by reconstructing their attack graphs and identifying the attack sources.

In the first part of this dissertation, we present our contribution to the family of PPM-based schemes for Internet Protocol (IP) traceback. Our proposed approach, Prediction-Based Scheme (PBS), consists of marking and traceback algorithms that reduce scheme convergence times by dealing with the problems of data loss and incomplete attack graphs exhibited by previous PPM-based schemes.

Compared to previous PPM-based schemes, the PBS marking algorithm ensures that traceback is possible …

Dual Channel-Based Network Traffic Authentication, David Irakiza

Doctoral Dissertations

In a local network or the Internet in general, data that is transmitted between two computers (also known as network traffic or simply, traffic) in that network is usually classified as being of a malicious or of a benign nature by a traffic authentication system employing databases of previously observed malicious or benign traffic signatures, i.e., blacklists or whitelists, respectively. These lists typically consist of either the destinations (i.e., IP addresses or domain names) to which traffic is being sent or the statistical properties of the traffic, e.g., packet size, rate of connection establishment, etc. The drawback with the list-based …

Studies Of Angular Correlations Of Jets With The Atlas Detector, Rajivalochan Subramaniam

Doctoral Dissertations

The strong force is one of the four fundamental forces and its strength is given by the coupling constant αs. The theory that describes the strong interaction is Quantum Chromodynamics (QCD) and it explains the interactions between quarks and gluons. The strong coupling constant is the only free parameter in the QCD Lagrangian if the quark masses are fixed. Determinations of αs provide direct tests of perturbative QCD calculations. The collimated sprays of particles originating from the quark and gluon interactions are called jets. The ratio of jet cross sections are sensitive to α s and are …

Positive Hysteresis And Negative Hysteresis In Human Gait Transition, Mohammad Abdolvahab

Doctoral Dissertations

The present study investigates the dynamics of human walk-to-run (W-R) and run-to-walk (R-W) transitions. Most particularly, it investigates the difference between the critical velocities (specifically, Froude Numbers) at which walk transitions to run and run transitions to walk, a difference referred to as hysteresis. Its primary theoretical focus is expressing the dynamics that distinguishes between (a) the classically observed positive hysteresis in which R-W critical Froude Number > W-R critical Froude Number and (b) the recently observed negative hysteresis in which R-W critical Froude Number < W-R critical Froude Number. Four experiments on treadmill locomotion of young adults were directed at the dependence of hysteresis on (1) treadmill speed (constantly increasing or decreasing), (2) treadmill slope (0%, 5% and 10%), (3) concurrent cognitive activity (no counting, counting back from a given number by ones, by sevens), and (4) so-called functional distance (report of upcoming transition speed while walking or running on the treadmill versus while standing off the treadmill). In respect to Experiment 1, treadmill speed did not affect critical Froude Numbers and, perforce, degrees of positive hysteresis. In respect to Experiment 2, treadmill inclination affected the critical Froude Numbers but not the degree of positive hysteresis. In respect to Experiment 3, the more difficult the cognitive activity concurrent with treadmill locomotion the larger the positive hysteresis. In respect to Experiment 4, judging the treadmill speed at which a gait transition was expected when standing off the treadmill yielded negative hysteresis in contrast to the positive hysteresis when walking or running on the treadmill. The results of the four experiments were addressed through a synergetic model of positive and negative hysteresis adapted from Lopresti-Goodman et al. (2013). The results were found to be consistent with principles of self- organization.

Comprehensive Numerical Modeling Of Heat Pipe-Assisted Latent Heat Thermal Energy Storage Systems, Nourouddin Sharifi

Doctoral Dissertations

Comprehensive Numerical Modeling of Heat Pipe-Assisted Latent Heat Thermal Energy Storage Systems

Nourouddin Sharifi, PhD

University of Connecticut, 2014

Latent heat thermal energy storage (LHTES) is capable of higher energy storage densities effectively reducing storage volume and cost compared to other thermal energy storage systems. However, most inexpensive phase change materials (PCMs) exhibit low thermal conductivities, potentially limiting the rates of heat transfer, and consequently, the use of LHTES in a variety of applications. To compensate for this major drawback, three different approaches to improve heat transfer rates are presented in this work: (i) utilization of fins, (ii) incorporation of …

Explaining Pedestrian And Vehicular Crashes In Conjunction With Exposure Measures, Md Saidul Islam

Doctoral Dissertations

The first part of the research presents an investigation of pedestrian conflicts and crash count models to learn which exposure measures and roadway or roadside characteristics significantly influence pedestrian safety at road crossings. The results show that minor and serious conflicts are marginally significant in predicting total pedestrian crashes together with crossing distance and building setback. This suggests that these conflicts may be a good surrogate for crashes in analyzing pedestrian safety. Greater crossing distance and small building setbacks are both found to be associated with larger numbers of pedestrian-vehicle crashes. In the second part of the research we assembled …

Crime And Supermarket Locations: Implications For Food Access, Adam N. Rabinowitz

Doctoral Dissertations

Food access in the United States has become a major policy issue that has received increased attention due to concerns of equality, health, and economic development. Since the initial academic research began to call attention to this issue a variety of tools have been developed to help identify geographic areas that have limited access to food. Supermarkets have taken the main focus as they provide for opportunities for fresh foods, greater variety, and lower prices.

While the existing research has looked to describe factors that explain the characteristics of communities with reduced supermarket access, crime has often been ignored or …

Switchgrass (Panicum Virgatum L.) Distribution, Genetic Diversity, And Pollen-Mediated Gene Flow, Geoffrey I. Ecker

Doctoral Dissertations

Switchgrass (Panicum virgatum L.) is a North American grass being optimized to serve as a biofuel crop. The cultivation of switchgrass carrying novel genes and traits has made ecological risk assessment (ERA) research critical for predicting the effects of pollen dispersal and pollen-mediated gene flow on local switchgrass populations and plant communities. The goals of this research were to: 1) Understand Panicum species distribution, habitat types, and plant communities; 2) Create a Lagrangian model of pollen dispersal informed by data on pollen longevity, size, and wind fields; 3) Determine the potential for interspecific hybridization between switchgrass and other Panicum …

A Circuit Model Of The Neural Network For Time-Optimal Control Of Horizontal Saccadic Eye Movements, Alireza Ghahari

Doctoral Dissertations

This dissertation research focused on computational systems neuroscience for modeling the major midbrain structures in the control of conjugate goal-directed horizontal human and monkey saccadic eye movements. Given the complexity of the saccade generator in a large-scale spiking neural network (SNN), a combination of extant behavioral, neurophysiological, and anatomical studies needs to be primarily referenced. These studies provide abundant evidence that an SNN is well suited to evoke the properties of the firing patterns of the premotor neurons during the pulse and slide phases of innervation in a saccade. However, none of the studies have presented a demonstration of the …

Three Essays In The Economics Of Food Marketing, Xun Li

Doctoral Dissertations

This dissertation consists of three empirical studies of food marketing, which directly and indirectly affects consumers’ purchase behavior, reshapes their eating habit, and alters social welfare. Chapter one investigates the advertising spillover effects using the carbonated soft drinks market as a case study. In this chapter, spillover effects are modeled using the conventional linear and constant elasticity of substitution (CES) advertising production functions. Empirical results confirm strong and positive brand advertising spillover effects across brands belonging to the same company as well as negative spillover effects from advertising by competitors. Empirical results also indicate that the CES advertising production function …

Algorithms For Blind Rendezvous In Wireless Networks, Sixia Chen

Doctoral Dissertations

Blind rendezvous is a fundamental problem in wireless networks. Rendezvous problems involve a collection of agents, or nodes, each of which would like to discover and communicate with the other agents in the collection who are within its transmission range. Two agents are said to rendezvous when they become aware of one another and are able to communicate. Blindness refers to a set of constraints on any algorithm that is to guarantee rendezvous in a typical wireless network.

• Agents begin with no knowledge of one another and have no means of coordination other than the common radio channels available to …

The Effects Of Construct Shift And Model-Data Misfit On Estimates Of Growth Using Vertical Scales, Melissa Eastwood

Doctoral Dissertations

The primary purpose of this study was to examine the extent to which violations of item response model dimensionality assumptions, model misspecification, and choice of calibration procedure affect accuracy of item and person parameter estimates and the estimation of growth in an IRT vertical scaling application using mixed-format tests. The assumptions of unidimensionality within grade and construct invariance across grades was of primary interest, as they may not hold in a vertical scaling context. Real data from a statewide assessment spanning six grades and two subject areas were analyzed to investigate the presence of construct shift and explore issues of …

Morphology And Function Of The Drinking Apparatus In Hummingbirds, Alejandro Rico-Guevara

Doctoral Dissertations

My research aims to answer the questions: How do hummingbirds feed? And, how do the mechanics of feeding define the limits and adaptive values of feeding behaviors? I meticulously study every step of nectar capture and ingestion. My dissertation chapters are organized following a morpho-functional and feeding sequence approach: 1) Feeding Apparatus Morphology; with emphasis on the understudied morphology of the tongue grooves and bill tongue coupling. 2) Tongue Tip Dynamics; how hummingbird tongues entrap nectar. 3) Tongue Grooves Functioning: how the tongue acts as an elastic micropump while collecting nectar. 4) Bill Tip Mechanics; internal bill structures that aid …

Heat Transfer And Thermodynamic Analysis Of Heat Pipe-Assisted Latent Heat Thermal Energy Storage Systems For Concentrating Solar Power Applications, Hamidreza Shabgard

Doctoral Dissertations

Thermal energy storage (TES) is the key advantage of concentrating solar power (CSP) systems. Among various types of TES, latent heat thermal energy storage (LHTES) benefits from large energy density and virtually isothermal operation that can potentially reduce the cost of TES systems significantly. However, most of the phase change materials (PCMs) used in LHTES systems have a prohibitively low thermal conductivity. This work presents a novel approach to substantially improve the heat transfer rates of a LHTES system by incorporating heat pipes (HPs) and/or thermosyphons (TSs) to circumvent the large thermal resistances of the PCMs. The basic design of …

Excitatory Post Synaptic Potentials In Dendritic Spines On Basal Dendrites Of L5 Pyramidal Neurons, Erika A. Hoyos-Ramirez

Doctoral Dissertations

Excitatory postsynaptic potentials (EPSPs) occur when the neurotransmitter glutamate binds to postsynaptic receptors located on specialized/pleomorphic structures called dendritic spines, which are attached to dendrites through spine necks. These potentials constitute the input signals that neurons must process in order to maintain proper brain function, but due to the small size of spines, direct measurement of these potentials at their site of origin has remained elusive. In this study, we combine voltage-sensitive dye recording with glutamate-uncaging to directly measure the amplitude and duration of unitary EPSPs in single spines in cortical layer 5 pyramidal neurons from mouse brain slices. Our …

Quantum Apices: Identifying Limits Of Entanglement, Nonlocality, & Contextuality, Elie S. Wolfe

Doctoral Dissertations

This work develops analytic methods to quantitatively demarcate quantum reality from its subset of classical phenomenon, as well as from the superset of general probabilistic theories. Regarding quantum nonlocality, we discuss how to determine the quantum limit of Bell-type linear inequalities. In contrast to semidefinite programming approaches, our method allows for the consideration of inequalities with abstract weights, by means of leveraging the Hermiticity of quantum states. Recognizing that classical correlations correspond to measurements made on separable states, we also introduce a practical method for obtaining sufficient separability criteria. We specifically vet the candidacy of driven and undriven superradiance as …

Synchrotron-Based X-Ray Imaging To Characterize Structural And Chemical Changes In Energy Materials, William M. Harris

Doctoral Dissertations

The development of increasingly complex, multiphase, and micro-scale composite materials has led to a simultaneous increase in the demand for characterization techniques capable of examining and evaluating the quality of these material systems. These types of composites, which can include such devices as fuel cell and battery electrodes and dense gas separation membranes, display an intimate link between the microstructural arrangement of the various constituent phases and the device performance. This connection is often manifested through coupled transport, reaction, and degradation processes occurring at the micro-scale and conformal to the detailed phase distribution. Therefore, direct examination of the microstructure is …

Traveling Fronts To Reaction Diffusion Equations With Fractional Laplacians, Tingting Huan

Doctoral Dissertations

We consider the traveling fronts of the reaction diffusion equations with fractional Laplacian. We show the nonexistence of the traveling fronts in the combustion model with fractional Laplacian in the supercritical case. Our method can be used to give a direct and simple proof of the nonexistence of traveling fronts for the Fisher-KPP nonlinearity. Also we prove the existence and nonexistence of traveling fronts for different ranges of the fractional power in the generalized Fisher-KPP type model.

Ionomer Morphology, Solution To Film Thermodynamics, Molecule Transport, Physical Properties, And Water Desalination Via Electrodialysis, Donghui Wang

Doctoral Dissertations

Archival abstract submitted

Synthesis Of Next Generation Dielectric Materials Through Rational Exploration Of Chemical Space, Aaron Baldwin

Doctoral Dissertations

Archival abstract submitted

Early Predictors Of Executive Function Abilities In School-Aged Children With Autism Spectrum Disorders, Kelley Knoch

Doctoral Dissertations

Executive Functions (EF) are a set of cognitive processes that direct and regulate behavior for the purpose of future goal attainment. These processes include working memory, inhibition, cognitive flexibility, planning, and fluency. Previous research has delineated impairments in individual processes of EF that may be related to the core social and communicative deficits typically found in children and adolescents with Autism Spectrum Disorders (ASDs). This line of research thus far has yielded mixed results, and further clarification is needed to determine if EF are directly related to clinical measures of ASD symptoms. Understanding the development of EF is critical, as …

Investigating The Effect Of Increasing Positive Teacher-Student Interactions On Adolescent Behavior And Teacher-Student Relationships, Jennifer J. Gallucci

Doctoral Dissertations

Research suggests that positive interactions between teachers and students are linked to a myriad of positive academic and behavioral student outcomes (Connor, Son, Hindman, & Morrison, 2005; Curby, Rimm-Kaufman, & Ponitz, 2009; Mashburn et al., 2008; Merritt, Wanless, Rimm-Kaufman, Comeron & Peugh, 2012). However, interactions between teachers and students with learning or behavioral difficulties are often characterized by fewer positive interactions (Cook & Cameron, 2008). Available interventions to increase positivity between teachers and students reveal major limitations. To address this issue, feasible and effective interventions to increase positive interactions between teachers and students are needed. As such, the objective of …

Improvements On Segment Based Contours Method For Dna Microarray Image Segmentation, Yang Li

Doctoral Dissertations

DNA microarray is an efficient biotechnology tool for scientists to measure the expression levels of large numbers of genes, simultaneously. To obtain the gene expression, microarray image analysis needs to be conducted. Microarray image segmentation is a fundamental step in the microarray analysis process. Segmentation gives the intensities of each probe spot in the array image, and those intensities are used to calculate the gene expression in subsequent analysis procedures. Therefore, more accurate and efficient microarray image segmentation methods are being pursued all the time.

In this dissertation, we are making efforts to obtain more accurate image segmentation results. We …

Quantum Levitation Using Metamaterials, Venkatesh K. Pappakrishnan

Doctoral Dissertations

The emergence of an attractive vacuum force (Casimir force) between two purely dielectric materials can lead to an increase in the friction and the stiction effects in nanoscale devices, resulting in degradation or decreased performance. Thus, it is of high practical importance that the conditions for the reversal of the Casimir force from attractive to repulsive are identified. Although the repulsive Casimir force has been considered for high dielectric materials as an intermediate (between the plates) medium, so far no realistic system has been proposed that can demonstrate quantum levitation with air/vacuum as a host medium. Since air is the …

Analysis Of A Mathematical Model For The Heave Motion Of A Micro Aerial Vehicle With Flexible Wings Having Non-Local Damping Effects, Jonathan B. Walters

Doctoral Dissertations

In this work we analyze a one dimensional model for a flexible wing micro aerial vehicle which can undergo heaving motion. The vehicle is modeled with a non-local type of internal damping known as spatial hysteresis as well as viscous external damping. We present a rigorous theoretical analysis of the model proving that the linearly approximated system is well-posed and the first order feedback system operators generate exponentially stable C0–semigroups.

Furthermore, we present numerical simulations of control designs used on the linearly approximated model to control the associated nonlinear model in two different strategies. The first strategy used to …

On Electromagnetic And Quantum Invisibility, Pattabhiraju Chowdary Mundru

Doctoral Dissertations

The principle objective of this dissertation is to investigate the fundamental properties of electromagnetic wave interactions with artificially fabricated materials i.e., metamaterials for application in advanced stealth technology called electromagnetic cloaking. The main goal is to theoretically design a metamaterial shell around an object that completely eliminates the dipolar and higher order multipolar scattering, thus making the object invisible.

In this context, we developed a quasi-effective medium theory that determines the optical properties of multi-layered-composites beyond the quasi-static limit. The proposed theory exactly reproduces the far-field scattering/extinction cross sections through an iterative process in which mode-dependent quasi-effective impedances of the …

A Knowledge Discovery Approach For The Detection Of Power Grid State Variable Attacks, Nathan Wallace

Doctoral Dissertations

As the level of sophistication in power system technologies increases, the amount of system state parameters being recorded also increases. This data not only provides an opportunity for monitoring and diagnostics of a power system, but it also creates an environment wherein security can be maintained. Being able to extract relevant information from this pool of data is one of the key challenges still yet to be obtained in the smart grid. The potential exists for the creation of innovative power grid cybersecurity applications, which harness the information gained from advanced analytics. Such analytics can be based on the extraction …

Instructional Leadership Practices Of Louisiana Elementary And Middle School Principals, Michael Ramon Hicks

Doctoral Dissertations

For principals in Louisiana, instructional leadership, in theory and practice, informs the foundation of ways they are trained and evaluated as school leaders. Identifying the specific instructional leadership practices that are tied to gains in student achievement has become critical for principals, and more importantly for their students. The focus of this research is in the area of principals' instructional leadership practices and student achievement in two northwestern Louisiana school districts. Such a study is important in order to provide effective training and development to Louisiana principals.

The purpose of the study was to investigate the relationship between teachers' perceptions …

The Impact Of Stereotype Threat On High School Females' Math Performance: Moderators And An Intervention, Jacqueline Hebert Ball

Doctoral Dissertations

Historically, there has been a significant gender gap in science, technology, engineering, and mathematics (STEM) careers (Beede et al., 2011; National Science Foundation, 2009), which has been attributed to females' lack of interest and pursuit of careers in these fields (Singletary et al., 2009). In the past, the lack of female participation in these careers was explained by a difference in natural abilities in these areas, especially in mathematics (Benbow & Stanley, 1983); however, research has shown that females are capable of performing just as well as males in the same age group in math (Smith & White, 2002; Spencer …

The Relationship Between Configurations Of The New Tech High School Model And Student Achievement, Kyle Grant Machen

Doctoral Dissertations

Traditional educational environments have been documented as being potential barriers to improving student achievement. Consequently, reform models, such as the New Tech High School (NTHS), were created to enable educators to fundamentally rethink teaching and learning. The purpose of this study was to ascertain whether the NTHS, as a reform model, is an effective vehicle to increase student achievement. The study examined the relationship between NTHS models and desired outcomes of the New Tech Network (NTN) as indicated by: state proficiency exams, End of Course (EOC) exams; a college and career readiness exam, the American College Test (ACT); and, School …