Digital Commons Network^™

New Polyanion-Based Cathode Materials For Alkali-Ion Batteries, Hooman Yaghoobnejad Asl

Doctoral Dissertations

"A number of new materials have been discovered through exploratory synthesis with the aim to be studied as the positive electrode (cathode) in Li-ion and Na-ion batteries. The focus has been set on the ease of synthesis, cost and availability of active ingredients in the battery, and decent cycle-life performance through a combination of iron and several polyanionic ligands. An emphasis has been placed also on phosphite (HPO₃^2-) as a polyanionic ligand, mainly due to the fact that it has not been studied seriously before as a polyanion for cathode materials. The concept of mixed polyanions, for …

Efficient Time-Dependent System Reliability Analysis, Zhifu Zhu

Doctoral Dissertations

"Engineering systems are usually subjected to time-variant loads and operate under time-dependent uncertainty; system performances are therefore time-dependent. Accurate and efficient estimate of system reliability is crucial for decision makings on system design, lifetime cost estimate, maintenance strategy, etc. Although significant progresses have been made in time-independent reliability analysis for components and systems, time-dependent system reliability methodologies are still limited. This dissertation is motivated by the need of accurate and effective reliability prediction for engineering systems under time-dependent uncertainty. Based on the classic First and Second Order Reliability Method (FORM and SORM), a system reliability method is developed for multidisciplinary …

Wetting Kinetics In Forced Spreading, Amer Mohammad Al-Shareef

Doctoral Dissertations

"Under dynamic conditions, the dynamic contact angle (the angle that the liquid makes with the solid) of a liquid on a solid surface varies dramatically with substrate velocity from its equilibrium value. Experimental data of the dynamic contact angles for polydimethylsiloxane (PDMS or silicone oil) under air on a glass substrate coated with teflon, for water under PDMS, for solutions of the polymer polyethylene oxide (PEO) under air, for solutions of PEO under PDMS, were obtained to simulate and understand the systems of brine or brine containing a polymer displacing viscous crude. A variety of solid substrates were used other …

Small Sample Confidence Bands For The Survival Functions Under Proportional Hazards Model, Emad Mohamed Abdurasul

Doctoral Dissertations

"In this work, a saddlepoint-based method is developed for generating small sample confidence bands for the population survival function from the Kaplan-Meier (KM), the product limit (PL), and Abdushukurov-Cheng-Lin (ACL) survival function estimators, under the proportional hazards model. In the process the exact distribution of these estimators is derived and developed mid-population tolerance bands for said estimators. The proposed saddlepoint method depends upon the Mellin transform of the zero-truncated survival estimator which is derived for the KM, PL, and ACL estimators. These transforms are inverted via saddlepoint approximations to yield highly accurate approximations to the cumulative distribution functions of the …

The Role Of Pre-Existing Basement Fabrics In The Initiation Of Continental Rifting: The Okavango Rift Zone, Botswana, Angelica Alvarez Naranjo

Doctoral Dissertations

"Integrated geophysical, remote sensing, and field investigations of the Okavango Rift Zone (ORZ), Botswana indicate that a feedback between optimum-oriented basement structures and fluid flow influence the nucleation and growth of continental rifts in their incipient stages. The ORZ, the youngest rift of the East African Rift System, occurs within a Proterozoic inter-cratonic suture zone - the NE-trending Precambrian Damara/Ghanzi-Chobe orogenic belts. The Pleistocene to Holocene ORZ forms a ~450 km long and ~100 km wide half-graben bounded by NE-trending normal faults. Basement units within the Damara/Ghanzi-Chobe orogenic belts exhibit a well-developed NE-trending linear fabric (045-065) defined by parallel limbs …

Approximation For Single-Channel Multi-Server Queues And Queuing Networks With Generally Distributed Inter-Arrival And Service Times, Carlos Roberto Chaves

Doctoral Dissertations

"This dissertation is divided into two papers. The first paper is related to developing a closed-form approximation for single-channel multiple-server queues with generally distributed inter-arrival and service times, which are often found in numerous settings, e.g., airports and manufacturing systems. Unfortunately, exact models for such systems require distributions for the underlying random variables. Further, data for fitting distributions is sometimes not available, and one only has access to means and variances of the underlying input random variables. Under heavy traffic, excellent approximations already exist for this purpose. In the first paper, a new approximation method for medium traffic is presented. …

Modeling And Evaluation Of Moisture Diffusion In Polymer Composite Materials, Zhen Huo

Doctoral Dissertations

"Fiber-reinforced polymer composites have extensive applications due to their high specific strength, improved product performance, low maintenance and design flexibility. However, moisture absorbed by polymer composites during the service life plays a detrimental role in both the integrity and durability of composite structure. It is essential to understand the moisture diffusion behavior and induced damage in polymer matrix composites under varying hygrothermal conditions. In Part I, the moisture diffusion characteristics in hybrid composites using moisture concentration-dependent diffusion method have been investigated. Also, a multi-stage diffusion model was proposed to explain the deviation of moisture diffusion behavior for sandwich composites from …

Innovative Techniques For Seismic-Resistant Bridge Columns Under Ground Motion Excitations, Ayman A. Moustafa

Doctoral Dissertations

“This dissertation provides innovative alternative solutions for replacing conventional reinforced concrete columns. The proposed columns displayed enhanced seismic resistance and properties compared to their counterpart conventional columns. Two main techniques were followed and proposed to develop seismic-resistant columns. The first technique utilized rubberized concrete to internally enhance energy dissipation and damping. Materials testing of rubberized concrete with scrap tire replacement of fine aggregates were performed to evaluate its dynamic properties. Shaking table testing of a rubberized concrete column was performed and the behavior was compared to that of the conventional one. The rubberized column showed an increase of 16% in …

Single Particle-Inductively Coupled Plasma-Mass Spectrometry Technology Development For Metallic Nanoparticle Characterization In Complex Matrices, Yongbo Dan

Doctoral Dissertations

"As the rapid growing of nanotechnology, the release of engineered nanoparticles (ENPs) into the environment is inevitable. After entering the real environment, ENPs tend to react with different components of the ecosystem (e.g. water, soil, air, plants) and make their characterization difficult. Analyzing ENPs in these complex matrices still remains as a grand challenge. ENPs characterization is normally the first step of risk assessment. Current analytical techniques have shown some limitations in revealing the unique characteristics of ENPs in complex matrices and reliable analytical techniques are in urgent need. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is an emerging …

Integrated Geophysical Approach Using Electrical Resistivity Tomography And Multichannel Analysis Of Surface Wave In Assessing Wilson Spring Development, Ibrahim E. Ahmed

Doctoral Dissertations

"This research investigated fractured zones leading to preferential flow paths of Wilson Spring. In this context, electrical resistivity tomography (ERT) data and multi-channel analyses of surface waves (MASW) data were acquired at studied site with the purpose of mapping a variable depth to top of bedrock and geological structures.

Interpretation of the boreholes, MASW, and ERT data indicated that a depth to top of rock does vary significantly at the studied site due to many solution-widened fractures. Multiple near-vertical solution-widened fractures were mapped in the studied site based on the interpretation of the ERT data. The mapped solution-widened fractures appear …

Repetitive Process Control Of Additive Manufacturing With Application To Laser Metal Deposition, Patrick M. Sammons

Doctoral Dissertations

"Additive Manufacturing (AM) is a set of manufacturing processes which has promise in the production of complex, functional structures that cannot be fabricated with conventional manufacturing and the repair of high-value parts. However, a significant challenge to the adoption of additive manufacturing processes to these applications is proper process control. In order to enable closed-loop process control compact models suitable for control design and for describing the layer-by-layer material addition process are needed. This dissertation proposes a two-dimensional modeling and control framework, with an application to a specific metal-based AM process, whereby the deposition of the current layer is affected …

Bioactivity/Cytotoxicity Of Micro-/Nano-Materials And Novel Development Of Fiber-Optic Probes For Single Cell Monitoring, Qingbo Yang

Doctoral Dissertations

"Manufactured nano-/micro-materials (MNMs) have been widely used and their interactions with niche biological environment are highly concerned for both of their biohazardous and bioactive effects, whereas no available comprehensive evaluations or regulations have been provided yet. This dissertation thus focuses on three major aspects: 1) fundamental toxicity understandings of a typical MNMs (zinc oxide nanoparticles), 2) bioactivity evaluations of representative bioactive MNMs, and 3) development of novel micro-probes for high spatial resolution monitoring. Firstly, the NP's concentration, irradiation, hydrodynamic size, and the localized pH, ionic strength, NP zeta-potential as well as dissolved oxygen levels were found correlated with the production …

An Investigation Of Multimedia Instruction, The Modality Principle, And Reading Comprehension In Fourth-Grade Classrooms, Laura Angela Sandoval

Doctoral Dissertations

Elementary-school teachers are faced with the responsibility of finding the most effective ways to educate their students using multimedia approaches. The use of instruction with visuals and audio has resulted in positive learning outcomes on retention and transfer tasks for junior-high and high-school students. This approach that results in the modality principle has been tested less frequently in elementary-aged students.

The purpose of this study was to examine two different multimedia instructional approaches to investigate which condition offers beneficial learning outcomes through recall and transfer assessments during a lesson on different types of energy in fourth-grade classrooms using a Powerpoint® …

Training In Summarizing Notes: Effects Of Teaching Students A Self-Regulation Study Strategy In Science Learning, Michelle Mendoza Nebres

Doctoral Dissertations

The last two decades of national data assessments reveal that there has been a sharp decline in nationwide standardized test scores. International assessment data show that in 2012 a very low amount of American students were performing at proficiency or above in science literacy. Research in science literacy education suggests that students benefit most when they are self-regulated (SR) learners. Unfortunately, SR poses a challenge for many students because students lack these skills. The effects of having learned few SR strategies at an early age may lead to long term learning difficulties—preventing students from achieving academic success in college and …

Girls And Stem (Science, Technology, Engineering, And Mathematics) In Catholic Schools: A Mixed Methods Exploration Of Interest, Confidence, And Perceptions Of Stem, Rachel Lynn-Pleis Mckenna

Doctoral Dissertations

Over the past decade, there has been a considerable push in emphasizing STEM—an acronym standing for Science, Technology, Engineering, and Math—as an integral aspect of educational curriculums. Even though research suggests that females tend to outperform males in standardized testing in STEM areas, they remain underrepresented in STEM careers and in the achievement of STEM degrees. In preparing this dissertation, therefore, the researcher investigated this issue by looking specifically at 4th- through 8th-grade girls in Catholic schools in the Diocese of San Jose, CA, which covers the Greater Silicon Valley region, one of the world's epicenters for technological innovations. In …

Effects Of The Green Life Nature Education Program For 4th Grade Students Who Attend Bay Area Title One Schools: A Mixed-Methods Study, Jessica Blundell

Doctoral Dissertations

This explanatory sequential design mixed-methods evaluation measures the effects of the GLNE program on (a) students’ personal and social skills (b) students’ stewardship of the environment (c) students’ knowledge and understanding of science concepts. Quantitative survey data and qualitative data from a phenomenologically-based study are analyzed and compared in order to understand the impact of attending Green Life Nature Education (GLNE) program, the only Bay Area Residential Outdoor School that serves urban youth with no-cost programing.

The quantitative data from student surveys implies that in general, attending GLNE has a neutral impact on students. While there were several negative impacts …

Applications Of Simulation And Optimization Techniques In Optimizing Room And Pillar Mining Systems, Angelina Konadu Anani

Doctoral Dissertations

"The goal of this research was to apply simulation and optimization techniques in solving mine design and production sequencing problems in room and pillar mines (R&P). The specific objectives were to: (1) apply Discrete Event Simulation (DES) to determine the optimal width of coal R&P panels under specific mining conditions; (2) investigate if the shuttle car fleet size used to mine a particular panel width is optimal in different segments of the panel; (3) test the hypothesis that binary integer linear programming (BILP) can be used to account for mining risk in R&P long range mine production sequencing; and (4) …

Assessment Of Highway Condition Using Combined Geophysical Surveys, Abdallah Alhadi Dera

Doctoral Dissertations

"Four pavement sections were investigated using ground penetrating radar (GPR) and Ultrasonic Surface Wave (USW). The objective of this research was to compare the effectiveness of two non-destructive geophysical tools, GPR and the PSPA, in assessing the condition of the pavements, composed of different construction materials. The GPR data were acquired using a 1.5 GHz antenna along five traverses spaced at two ft. intervals approximately 1000 ft. long. On the other hand, the PSPA data were acquired at the stations spaced at 1000 ft. along the five GPR traverses. Core samples were collected at each site to constrain the interpretation …

Synthesis And Functionalization Of A Triaryldiamine-Base Photoconductive/Photorefractive Composite, And Its Application To Aberrated Image Restoration, Yichen Liang

Doctoral Dissertations

"Organic photorefractive (PR) composites have recently emerged as an important class of materials for applications including high-density data storage, optical communication, and biomedical imaging. In an effort to further improve their performance, this study focused on the utilization of functionalized semiconductor nanocrystals to photosensitize triaryamine (TPD)-based PR composites, as well as the application of TPD-based PR composites in the restoration of aberrated optical information. A novel approach to functionalize CdSe quantum dot (QCdSe) was firstly introduced where the sulfonated triarydiamine (STPD) was used as charge-transporting ligand to passivate QCdSe. TPD-based photoconductive and PR composites were photosensitized with the STPD-passivated QCdSe …

Spectroscopy Of Quasibound And Long-Range Rydberg States Of Ultracold 85rb2, Ryan A. Carollo

Doctoral Dissertations

Ultracold atomic physics offers an experimentalist the opportunity to perform sensitive tests and measurements that are not possible at higher temperatures. In this case it allows for access to molecular states, through photoassociation, that are inaccessible to conventional techniques. We use photoassociation to measure quasi-bound levels of the 2 ¹Σ_g⁺ state of ⁸⁵Rb₂ . With these data, we examine a coupling between the short-range Hund’s case (c) 2 (0_g⁺ ) component and the long-range 2 (1_g ) state, which corresponds to the 1 ¹Π_g state. A second experiment studies the …

Self-Efficacy Of Middle School Teachers Responsible For Teaching Struggling Readers, Alison Burdick

Doctoral Dissertations

This qualitative study answers questions about school reform by utilizing professional learning for teachers who lack self-efficacy to teach reading to middle school students. The findings included higher self-efficacy and lower burnout rates for teachers. Implications from this study include a model for professional learning that recognizes teachers as adult learners and a system of professional development that provides daily opportunities for teachers to work together over problems of practice.

An Examination Of The Factors And Characteristics That Contribute To The Success Of Putnam Fellows, Robert A. J. Stroud

Doctoral Dissertations

The William Lowell Putnam Mathematical Competition is an intercollegiate mathematics competition for undergraduate college and university students in the United States and Canada and is regarded as the most prestigious and challenging mathematics competition in North America (Alexanderson, 2004; Grossman, 2002; Reznick, 1994; Schoenfeld, 1985). Students who earn the five highest scores on the examination are named Putnam Fellows and to date, despite the thousands of students who have taken the Putnam Examination, only 280 individuals have won the Putnam Competition. Clearly, based on their performance being named a Putnam Fellow is a remarkable achievement. In addition, Putnam Fellows go …

Lagrangian Approach To Modeling The Biodynamics Of The Upper Extremity: Applications To Collegiate Baseball Pitching, Matthew J. Solomito

Doctoral Dissertations

Biomechanical modeling can provide information regarding movement patterns and allow for an improved understanding of injury mechanisms. Biomechanical models typically rely on Newtonian mechanics leading to computationally intensive models; however, an often overlooked means of solving these same modeling needs is to apply the Lagrangian approach. This approach allows for a more direct means of solving the equations of motion; leading to more accurate models of human motion. The purpose of this project was to create a Lagrangian based model of the upper extremity to describe joint kinematics and kinetics as well as muscle kinetics during complex motion tasks.

The …

Motion And Noise Artifact Detection And Vital Signal Reconstruction In Ecg/Ppg Based Wearable Devices, Seyed Mohamad Amin Salehizadeh

Doctoral Dissertations

The design and development of wearable biosensor systems for health and wellness monitoring has garnered lots of attention in the scientific community and the industry during the past decade. When it comes to health and wellness monitoring, accurate measurements, analysis and estimations would be vital. One major challenge in achieving a high performance wearable health monitoring system is motion and noise artifacts. This consideration was the basis for this dissertation. This study presents different algorithms and signal processing techniques to address motion and noise artifact detection and vital signal reconstruction from electrocardiogram/photoplethysmogram recordings. Five vital signals including ECG, PPG, Heart …

On The Use Of The Linear Interaction Energy Method To Predict Affinities Of Charged Aromatic Ammines To Naturally Occurring Clay Minerals, Milinda A. Samaraweera

Doctoral Dissertations

This study presents the use of the linear interaction energy (LIE) method as a predictive tool to approximate the free energies of sorption of organic cations to naturally occurring clay mineral montmorillonite. One objective of this thesis is to explore the applicability and the accuracy of LIE, originated in the biochemistry field, as a predictive tool to estimate the free energies of sorption of organic cations to naturally occurring aluminosilicates. For this purpose, a set of charged aromatic amines sorbing to a prototypical homoionic clay montmorillonite (MMT) with calcium ions were modeled using molecular dynamics (MD) simulations. As the LIE …

The Perceived Relationship Of Leadership Behaviors To Teacher Preparedness For Implementing Connecticut’S Core Standards In Mathematics And Use Of Math Practices Aligned With Key Shifts In The Common Core, Angela Rossbach

Doctoral Dissertations

This study examines the relationship between specific leadership behaviors (i.e. the extent to which principals establish goals and expectations; plan, coordinate and evaluate teaching and the curriculum; and promote and participate in teacher learning) and teachers’ self-reported sense of preparedness and self-reported use of practices that align with the key shifts in the Common Core State Standards in Mathematics (CCSSM). Data for this quantitative study are from a teacher survey that was distributed electronically to all K-8 certified Connecticut teachers in fall, 2015.

Linear regression analysis shows significant relationships between the variables. Specifically, teachers who reported higher levels of principal …

Single Cell Resolution Mapping Of Mrna And Protein Expression Dynamics During Human Somatic Cell Reprogramming To Pluripotency, Frederick W. Kolling Iv

Doctoral Dissertations

In recent years, the fields of regenerative medicine and developmental biology have been revolutionized by the ability to reprogram adult somatic cells back to a pluripotent state, producing induced pluripotent stem cells (iPSCs) through the induction of the reprogramming factors OCT4, SOX2, KLF4 and c-MYC (OSKM). The promise of this technique has been somewhat limited by the low efficiency and long duration of the process which produces heterogeneous mixtures of cells in culture, many of which fail to fully reprogram over a 3-4 week period. Research in recent years has focused on the underlying mechanisms of reprogramming and identifying rate-limiting …

Efficient Methods For Mining Association Rules From Uncertain Data, Manal Hamed Alharbi

Doctoral Dissertations

Association rules mining is a common data mining problem that explores the relationships among items based on their occurrences in transactions. Traditional approaches to mine frequent patterns may not be applicable for several real life applications. There are many domains such as social networks, sensor networks, protein-protein interaction analysis, and inaccurate surveys where the data are uncertain. As opposed to deterministic or certain data where the occurrences of items in transactions are definite, in an uncertain database, the occurrence of an item in a transaction is characterized as a discrete random variable and thus represented by a probability distribution. In …

Electronic Structure Calculations Of Monolayer–Protected Gold Nanoclusters To Aid Spectroscopic Analysis, Neranjan V. Perera

Doctoral Dissertations

The underlying goal of this thesis dissertation is to simulate small monolayer protected clusters (MPCs) via quantum mechanics and molecular mechanics calculations to derive electronic, structural, and dynamical properties. First we specifically focus on monolayers consisting of thiolated oligopeptides and alkanethiols. We construct MPCs with a layer of oligopeptides consisting of α-aminoisobutyric acid units. We use Monte Carlo simulations to determine peptide arrangements and folding. We then perform NMR chemical shifts calculations and compare to experimental measurements to validate the predicted structure.

The native -1 oxidation state can be oxidized into 0 and to +1 charge states. The neutral charge …

Modeling Heterogeneity In Growth Mixture Models: A Case Study Of Model Selection Using Direct Behavior Rating, Janice Kooken

Doctoral Dissertations

This study investigates student classroom behavior changes over one year using multilevel growth mixture modeling to demonstrate how modifying assumptions of invariance affects parameter estimates, number of classes, and proportion of students assigned to each class. Current best practices for growth mixture modeling emphasize the importance of the proper specification, but the impact of these assumptions on the parameters and latent class composition has not been thoroughly addressed in applied research in multilevel growth mixture models. Using the Direct Behavior Rating Single Item Scale measures from 1975 students in lower elementary, upper elementary and middle school, a series of models …