# Physical Sciences and Mathematics Commons™

Articles 1 - 30 of 1137

## Full-Text Articles in Physical Sciences and Mathematics

Improving Reader Motivation With Machine Learning, Tanner A. Bohn Apr 2021

#### Improving Reader Motivation With Machine Learning, Tanner A. Bohn

##### Electronic Thesis and Dissertation Repository

This thesis focuses on the problem of increasing reading motivation with machine learning (ML). The act of reading is central to modern human life, and there is much to be gained by improving the reading experience. For example, the internal reading motivation of students, especially their interest and enjoyment in reading, are important factors in their academic success.

There are many topics in natural language processing (NLP) which can be applied to improving the reading experience in terms of readability, comprehension, reading speed, motivation, etc. Such topics include personalized recommendation, headline optimization, text simplification, and many others. However, to the ...

#### Generating Effective Sentence Representations: Deep Learning And Reinforcement Learning Approaches, Mahtab Ahmed

##### Electronic Thesis and Dissertation Repository

Natural language processing (NLP) is one of the most important technologies of the information age. Understanding complex language utterances is also a crucial part of artificial intelligence. Many Natural Language applications are powered by machine learning models performing a large variety of underlying tasks. Recently, deep learning approaches have obtained very high performance across many NLP tasks. In order to achieve this high level of performance, it is crucial for computers to have an appropriate representation of sentences. The tasks addressed in the thesis are best approached having shallow semantic representations. These representations are vectors that are then embedded in ...

Apr 2021

#### A Lightweight And Explainable Citation Recommendation System, Juncheng Yin

##### Electronic Thesis and Dissertation Repository

The increased pressure of publications makes it more and more difficult for researchers to find appropriate papers to cite quickly and accurately. Context-aware citation recommendation, which can provide users suggestions mainly based on local citation contexts, has been shown to be helpful to alleviate this problem. However, previous works mainly use RNN models and their variance, which tend to be highly complicated with heavy-weight computation. In this paper, we propose a lightweight and explainable model that is quick to train and obtains high performance. Our model is based on a pre-trained sentence embedding model and trained with triplet loss. Quantitative ...

#### Population And Evolution Dynamics In Predator-Prey Systems With Anti-Predation Responses, Yang Wang

##### Electronic Thesis and Dissertation Repository

This thesis studies the impact of anti-predation strategy on the population dynamics of predator-prey interactions. This work includes three research projects.

In the first project, we study a system of delay differential equations by considering both benefit and cost of anti-predation response, as well as a time delay in the transfer of biomass from the prey to the predator after predation. We reveal some insights on how the anti-predation response level and the biomass transfer delay jointly affect the population dynamics; we also show how the nonlinearity in the predation term mediated by the fear effect affects the long term ...

#### Geological, Mineralogical And Geochemical Process Controls On Ni Tenor Variations In The Metasedimentary-Hosted Thompson 1d Orebody At Vale’S Thompson Mine (T3), Northern Manitoba, Canada, Povilas G. Grigutis

##### Electronic Thesis and Dissertation Repository

The Proterozoic Thompson Nickel Belt (TNB) contains rift-related mafic-ultramafic igneous rocks, in a collisional belt at the NW margin of the Archean Superior province in Northern Manitoba, Canada. The TNB hosts world class Ni-Cu-(PGE) mineralization, that has undergone polyphase deformation (D1 – D4) and upper amphibolite to lower granulite facies metamorphism, up to ~750ºC and 7.5 kbars (Lightfoot et al., 2017). Komatiitic magmas (1880 ± 5 Ma; Hulbert et al., 2005) fertile in Ni & PGE elements intruded Ospwagan Group metasedimentary sequences and through sulfur assimilation and segregation produced primary magmatic sulfides (Lesher and Burnham, 2001).

The TNB metasedimentary-hosted ores of the Thompson Deposit (T1 and T3) are interpreted to have formed from the complete remobilization and relocation of sulfides from primary ultramafic boudins (Bleeker, 1990). The aim of this study was to assess geological, mineralogical and geochemical controls on the Ni tenor of sulfide (% Ni normalized to 100% sulfide), and to understand why Ni tenor in the metasedimentary-hosted Thompson deposits is higher than those of primary ultramafic associated mineralization, like the Pipe and Birchtree Deposits. The research focused on the Thompson 1D orebody at T3 mine because of the large variability of nickel tenor, ranging from(8-16 wt% Ni).

The two most significant findings of this study are that; Ni-Co-Pd tenors are highest in shear-hosted massive sulfides and that there is a positive correlation between pyrite modal abundance and Ni-Co tenor. Pyrite is ...

Apr 2021

#### Formation Of Supermassive Black Holes In The Early Universe, Arpan Das

##### Electronic Thesis and Dissertation Repository

The aim of the work presented in this thesis is to understand the formation and growth of the seeds of the supermassive black holes in early universe. Supermassive black holes (SMBH) with masses larger than 108MSun have been observed when the Universe was only 800 Myr old. The formation and accretion history of the seeds of these supermassive black holes are a matter of debate. We consider the scenario of massive seed black hole formation which allows gas to directly collapse into a black hole (DCBH) of similar mass. Considering this scenario, we show that the mass ...

#### An Investigation On Flow Field Partitioning Related To The Rheological Heterogeneities And Its Application To Geological Examples, Ankit Bhandari

##### Electronic Thesis and Dissertation Repository

Earth’s lithosphere is heterogeneous and composed of rheologically distinct elements at various scales of observations. This causes the flow of rocks to vary with space and time, which may influence the formation of various kinds of geological rock records. This thesis provides quantitative solutions to some first-order problems in structural geology regarding this heterogeneous flow variation and thereby the development of various geological rock records at different scales of observations.

Pressure in a rheologically heterogeneous element may deviate from its ambient value and if significant, may influence the metamorphic assemblages. This might cause problems in the routine use of ...

#### A Deep Topical N-Gram Model And Topic Discovery On Covid-19 News And Research Manuscripts, Yuan Du

##### Electronic Thesis and Dissertation Repository

Topic modeling with the latent semantic analysis (LSA), the latent Dirichlet allocation (LDA) and the biterm topic model (BTM) has been successfully implemented and used in many areas, including movie reviews, recommender systems, and text summarization, etc. However, these models may become computationally intensive if tested on a humongous corpus. Considering the wide acceptance of machine learning based on deep neural networks, this research proposes two deep neural network (NN) variants, 2-layer NN and 3-layer NN of the LDA modeling techniques. The primary goal is to deal with problems with a large corpus using manageable computational resources.

This thesis analyze ...

Non-Linear Effects Of Solution Parameters And Gamma Radiation On Nickel Oxidation Dynamics, Razieh Karimihaghighi Mar 2021

#### Non-Linear Effects Of Solution Parameters And Gamma Radiation On Nickel Oxidation Dynamics, Razieh Karimihaghighi

##### Electronic Thesis and Dissertation Repository

Nickel is the main component in nickel-based superalloys which are known for their superior corrosion resistance and mechanical properties. These alloys are used in nuclear power plants, mainly for thin-walled heat exchanger tubing where these materials are exposed to a continuous flux of ionizing radiation. The long-term corrosion behaviour of these alloys at high temperatures and in the presence of gamma-radiation is not well understood. Moreover, the mechanism by which nickel improves the corrosion resistance of these alloys is also not known. Therefore, a mechanistic understanding of the nickel oxidation process is required to develop a predictive corrosion model for ...

Parallel Arbitrary-Precision Integer Arithmetic, Davood Mohajerani Mar 2021

#### Parallel Arbitrary-Precision Integer Arithmetic, Davood Mohajerani

##### Electronic Thesis and Dissertation Repository

Arbitrary-precision integer arithmetic computations are driven by applications in solving systems of polynomial equations and public-key cryptography. Such computations arise when high precision is required (with large input values that fit into multiple machine words), or to avoid coefficient overflow due to intermediate expression swell. Meanwhile, the growing demand for faster computation alongside the recent advances in the hardware technology have led to the development of a vast array of many-core and multi-core processors, accelerators, programming models, and language extensions (e.g. CUDA, OpenCL, and OpenACC for GPUs, and OpenMP and Cilk for multi-core CPUs). The massive computational power of ...

Galvanic Corrosion Of Carbon Steel Coupled To Copper In Used Nuclear Fuel Containers, Lindsay J. Braithwaite Mar 2021

#### Galvanic Corrosion Of Carbon Steel Coupled To Copper In Used Nuclear Fuel Containers, Lindsay J. Braithwaite

##### Electronic Thesis and Dissertation Repository

Deep geological containment of used nuclear fuel will rely on multiple engineered and natural barriers, two of which are the copper-coated used fuel containers and the compacted bentonite clay buffer boxes in which the containers will rest. This work focused on possible galvanic interactions between the copper coating and the steel substrate of the container, which may occur at a hypothetical through-coating defect. In the presence of various amounts of chloride, bentonite, and oxygen, corrosion of the copper/carbon steel couple was studied using electrochemical tests complemented by surface characterization and 3D X-ray imaging. We investigated the effects of copper-to-steel ...

#### Sample Size Formulas For Estimating Risk Ratios With The Modified Poisson Model For Binary Outcomes, Zhenni Xue

##### Electronic Thesis and Dissertation Repository

Sample size estimation is usually the first step in planning a research study. Too small a study cannot adequately address the objectives, while too large a study may waste resources or unethical. For binary outcomes, several sample size estimation methods are available based on logistic regression models, which focusing on odds ratios. In prospective studies, risk ratios are preferable for ease of interpretation and communication. In this thesis, we compared the power difference between the logistic regression model and the modified Poisson regression model via simulation studies. We then proposed sample size estimation formulas based on the modified Poisson regression ...

Feb 2021

#### A Physical Layer Framework For A Smart City Using Accumulative Bayesian Machine Learning, Razan E. Alfar

##### Electronic Thesis and Dissertation Repository

Smart cities are one of the most active research fields in the world, due to the various benefits and challenges associated with their implementation. A major challenge for smart cities is processing and transporting the huge volumes of data generated by the sensor network layer, which builds the fundamental physical layer. Ongoing research is needed to address the computational challenges arising in smart city environments, particularly to help ensure efficient operations around the sensor layer. To address this challenge, a novel physical layer framework is proposed that intelligently learns the behavior of the physical system to enable the agents to ...

#### High-Pressure Studies Of Flexible Metal-Organic Frameworks And Their Performance For Co2 Adsorption Using Infrared Spectroscopy, Boqing Li

##### Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are crystalline porous materials comprising metal ions/clusters and organic linkers. MOFs feature very large surface area and broad tunability, which distinguish them from traditional CO2 adsorbents. High external pressure can significantly modify the framework structures and CO2 adsorption properties of MOFs. MIL-53(Al) and NH2-MIL-53(Al) exhibit excellent CO2 affinity by forming hydrogen bonds between bridging OH groups and adsorbed CO2. We used in situ infrared spectroscopy to investigate the high-pressure performance of their framework structures and CO2 adsorption capacities. Diamond anvil cell was employed to apply high pressures ...

Feb 2021

#### Load Balancing And Resource Allocation In Smart Cities Using Reinforcement Learning, Aseel Alorbani

##### Electronic Thesis and Dissertation Repository

Today, smart city technology is being adopted by many municipal governments to improve their services and to adapt to growing and changing urban population. Implementing a smart city application can be one of the most challenging projects due to the complexity, requirements and constraints. Sensing devices and computing components can be numerous and heterogeneous. Increasingly, researchers working in the smart city arena are looking to leverage edge and cloud computing to support smart city development. This approach also brings a number of challenges. Two of the main challenges are resource allocation and load balancing of tasks associated with processing data ...

Feb 2021

#### Investigating The Corrosion Behaviour Of Ni-Based Alloys In Industrially Relevant Environments, Jeffrey D. Henderson

##### Electronic Thesis and Dissertation Repository

Typical engineering materials may experience high corrosion rates when exposed to aggressive service conditions. Such conditions include high concentrations of aggressive anions and oxidants, high solution acidity, and/or high temperatures. Alloys with high corrosion resistance may be selected to avoid material failure caused by corrosion, for example, Ni-Cr-Mo alloys. These alloys exhibit excellent corrosion resistance due to the formation of a passive oxide film, primarily containing Cr and Mo. However, film breakdown can result in localized corrosion, e.g., crevice corrosion. Localized corrosion processes can penetrate deep into the bulk alloy, threatening its integrity. While the oxide film and ...

Studies Of The Tilts Of Atmospheric Scatterers By Windprofiler Radars, Farnoush Attarzadeh Feb 2021

#### Studies Of The Tilts Of Atmospheric Scatterers By Windprofiler Radars, Farnoush Attarzadeh

##### Electronic Thesis and Dissertation Repository

MST (Mesosphere–Stratosphere–Troposphere) radars are powerful instruments for observing the differences in refractive indexes in the air. By tracking refractive index perturbations, these radars can determine wind speeds and turbulence strengths in the atmosphere from the ground up to 15 km altitude. In this project, we used 6 Doppler Radars to study the correlation between horizontal and vertical winds in the Troposphere to find scatterer tilts. However, instrumental effects due to small tilts in the radar beam can also cause such correlations, thus our studies cover that as well. Scatterers are best known for being the result of turbulence ...

Feb 2021

#### The Mean-Reverting 4/2 Stochastic Volatility Model: Properties And Financial Applications, Zhenxian Gong

##### Electronic Thesis and Dissertation Repository

Financial markets and instruments are continuously evolving, displaying new and more refined stylized facts. This requires regular reviews and empirical evaluations of advanced models. There is evidence in literature that supports stochastic volatility models over constant volatility models in capturing stylized facts such as "smile" and "skew" presented in implied volatility surfaces. In this thesis, we target commodity and volatility index markets, and develop a novel stochastic volatility model that incorporates mean-reverting property and 4/2 stochastic volatility process. Commodities and volatility indexes have been proved to be mean-reverting, which means their prices tend to revert to their long term ...

#### Plastic Debris In The Laurentian Great Lakes System, North America: Analysis Of Types, Abundances, And Sources, Ian A. Arturo

##### Electronic Thesis and Dissertation Repository

Understanding plastic pollution in the Laurentian Great Lakes system requires investigation of all plastic debris sizes and categories. Visible polymeric debris (VPD) mainly characterize shorelines, and microplastics (MPs;mm) are found in benthic and beach sediment. Field sampling of VPD from all five Great Lakes, visual and chemical identification of VPD types, and implementation of a matrix scoring technique (MST) indicate that plastic industries, urban areas, and shoreline recreation are major sources of VPD. Sampling for MPs in the St. Clair system, followed by preliminary density separation, and microscopy, suggest that wastewater treatment plants are a major source. This work ...

Jan 2021

#### Building Effective Network Security Frameworks Using Deep Transfer Learning Techniques, Harsh Dhillon

##### Electronic Thesis and Dissertation Repository

Network traffic is growing at an outpaced speed globally. According to the 2020 Cisco Annual Report, nearly two-thirds of the global population will have internet connectivity by the year 2023. The number of devices connected to IP networks will also triple the total world population's size by the same year. The vastness of forecasted network infrastructure opens opportunities for new technologies and businesses to take shape, but it also increases the surface of security vulnerabilities. The number of cyberattacks are growing worldwide and are becoming more diverse and sophisticated. Classic network intrusion detection architectures monitor a system to detect ...

Fundamental Transport Properties In Silicon Quantum Structures, Nazban M. Darukhanawalla Jan 2021

#### Fundamental Transport Properties In Silicon Quantum Structures, Nazban M. Darukhanawalla

##### Electronic Thesis and Dissertation Repository

In the field of silicon photonics, there is an effort to bridge the gap between electrical and optical signals on a single platform, creating a need for Si-based light sources. In this project, Si quantum structures – Si quantum wells and quantum dots in SiO2 were fabricated via solid state precipitation methods. Their properties were studied using X-ray photoelectron spectroscopy, photoluminescence and I-V measurements. Rutherford backscattering spectroscopy was used for depth analysis in monitoring the Si distribution. Different electrical transport mechanisms were explored to understand how an ensemble of silicon QD’s or a silicon quantum well behaves in an SiO2 ...

Dec 2020

#### The Effect Of The Initial Structure On The System Relaxation Time In Langevin Dynamics, Omid Mozafar

##### Electronic Thesis and Dissertation Repository

In recent decades, computer experiments have allowed an accurate and fundamental understanding of molecular mechanisms at the microscopic level, such as the process of relaxation at a stable physical state. However, computer simulations may sometimes produce non-physical results or relations due to the incompleteness of mathematical models describing physical systems. In this thesis, we have investigated whether the initial structure in a computer simulation affects the system relaxation time, which is denoted by τsys, in the Langevin NVT ensemble. We found that for an initial structure, which is inhomogeneous in the number density of atoms, the system relaxation time ...

One-Pot Synthesis Of Bicyclic Piperidines From Donor Acceptor Cyclopropanes, David G. Stephens Dec 2020

#### One-Pot Synthesis Of Bicyclic Piperidines From Donor Acceptor Cyclopropanes, David G. Stephens

##### Electronic Thesis and Dissertation Repository

The efficient synthesis of heterocyclic compounds is of great importance to organic chemistry. One method for achieving efficiency is through the use and development of one-pot reactions. This thesis describes the planning and development of an extension to the tandem cyclopropane opening Conia-ene reactivity previously reported. A search for a substrate capable of undergoing the reaction was undertaken and the reaction was optimized. The highest yielding conditions tested used catalytic Sc(OTf)3 and superstoichiometric ZnBr2, but other catalyst systems also worked. The optimized reaction conditions tolerated 6-membered rings well in addition to 7-membered rings in some rotationally restricted ...

Applying Front End Compiler Process To Parse Polynomials In Parallel, Amha W. Tsegaye Dec 2020

#### Applying Front End Compiler Process To Parse Polynomials In Parallel, Amha W. Tsegaye

##### Electronic Thesis and Dissertation Repository

Parsing large expressions, in particular large polynomial expressions, is an important task for computer algebra systems. Despite of the apparent simplicity of the problem, its efficient software implementation brings various challenges. Among them is the fact that this is a memory bound application for which a multi-threaded implementation is necessarily limited by the characteristics of the memory organization of supporting hardware.

In this thesis, we design, implement and experiment with a multi-threaded parser for large polynomial expressions. We extract parallelism by splitting the input character string, into meaningful sub-strings that can be parsed concurrently before being merged into a single ...

#### Longitudinal Partitioning Waveform Relaxation Methods For The Analysis Of Transmission Line Circuits, Tarik Menkad

##### Electronic Thesis and Dissertation Repository

Three research projects are presented in this manuscript. Projects one and two describe two waveform relaxation algorithms (WR) with longitudinal partitioning for the time-domain analysis of transmission line circuits. Project three presents theoretical results about the convergence of WR for chains of general circuits.

The first WR algorithm uses a assignment-partition procedure that relies on inserting external series combinations of positive and negative resistances into the circuit to control the speed of convergence of the algorithm. The convergence of the subsequent WR method is examined, and fast convergence is cast as a generic optimization problem in the frequency-domain. An automatic ...

#### The Rearrangement And Nucleophilic Addition Of Donor-Acceptor Cyclobutane: Novel Methodologies To Access Δ-Lactones And Ring-Opened Products, Donghyun Koo

##### Electronic Thesis and Dissertation Repository

Donor-acceptor (D-A) cyclobutanes are a well recognized building block in synthetic organic chemistry thanks to their unique reactivity. A variety of synthetic methodologies such as cycloaddition, rearrangement, and ring-opening addition of D-A cyclobutanes have been reported. Among them, the rearrangement reactions of D-A cyclobutanes have attracted less interest compared with other methodologies as they too often require extreme reaction conditions. To further explore the rearrangement reactions of D-A cyclobutanes, in this work a ring expansion rearrangement reaction of D-A cyclobutanes analogous to the Cloke–Wilson reaction of cyclopropanes was examined. By exploiting the solvent effect in a Brønsted acid system ...