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Articles 31 - 50 of 50
Full-Text Articles in Physical Sciences and Mathematics
Runoff Water Quality And Crop Growth As Affected By Wastewater-Derived Struvite, Machaela Morrison
Runoff Water Quality And Crop Growth As Affected By Wastewater-Derived Struvite, Machaela Morrison
Graduate Theses and Dissertations
Mined phosphate rock, used to produce phosphorus (P) fertilizers, is a finite resource. Struvite (MgNH4PO4 • 6H2O) that has been synthetically produced from a stock solution of known P and nitrogen (N) concentrations has been shown to be an effective, alternative fertilizer-P source for various crops. However, little is known about the runoff-water-quality implications from and the crop response to soil application of struvite created from an actual municipal wastewater source. This study consisted of two objectives: i) to evaluate the effects of soil [i.e., Creldon (Oxyaquic Fragiudalf), Dapue (Fluventic Hapludoll), Roxana (Typic Udifluvent), and Calloway (Aquic Fraglossudalf) series], fertilizer-P …
Poly(Ionic Liquid)S For Magnetic, Ionic, And Electrical Stimuli-Responsive Applications, Kayla Ann Foley
Poly(Ionic Liquid)S For Magnetic, Ionic, And Electrical Stimuli-Responsive Applications, Kayla Ann Foley
Graduate Theses and Dissertations
Poly(ionic liquid)s (PILs) are a fascinating subclass of strong polyelectrolytes formed from polymerizable ionic liquids. As a result of their unique properties and counterion exchangeability, PILs can exhibit conformation structure or material property changes in response to external stimuli such as changes in pH/ionic environment, magnetic fields, and electric potentials. In Chapter 1, a comprehensive review of PILs design as well as their stimuli-responsive behavior is provided. Additional motivation for each dissertation chapter is also discussed. In Chapter 2, magnetically responsive PILs (MPILs) are developed from complexing paramagnetic salts with a random PIL copolymer containing a metal-coordinating co-monomer, acrylamide. A …
Dpd Guided Insight On The Formation Process Of Polyethersulfone Membranes By Nonsolvent Induced Phase Separation And The Effects Of Additives, Eric Ledieu
Graduate Theses and Dissertations
Dissipative particle dynamics (DPD), a coarse grain simulation method, was applied to the membrane formation process of non-solvent induced phase separation (NIPS) to gain further insight on the mechanism of certain variables and how they affect the final morphology. NIPS involves two solutions, an organic polymer dissolved in an organic solvent colloquially called the dope and an aqueous coagulation bath, brought into contact with one another. The solvents then mix, causing the polymer to fall out of solution as an asymmetric membrane with a dense surface layer and a more open subsurface layer in response to the decreasing solubility. Polyethersulfone …
Open Source Intelligence For Cybersecurity Events Via Twitter Data, Dakota Dale
Open Source Intelligence For Cybersecurity Events Via Twitter Data, Dakota Dale
Graduate Theses and Dissertations
Open-Source Intelligence (OSINT) is largely regarded as a necessary component for cybersecurity intelligence gathering to secure network systems. With the advancement of artificial intelligence (AI) and increasing usage of social media, like Twitter, we have a unique opportunity to obtain and aggregate information from social media. In this study, we propose an AI-based scheme capable of automatically pulling information from Twitter, filtering out security-irrelevant tweets, performing natural language analysis to correlate the tweets about each cybersecurity event (e.g., a malware campaign), and validating the information. This scheme has many applications, such as providing a means for security operators to gain …
Biochar As A Lake Management Option For Harmful Algal Blooms: Lab Experiments And Bioassays, Brittany Mc Intyre
Biochar As A Lake Management Option For Harmful Algal Blooms: Lab Experiments And Bioassays, Brittany Mc Intyre
Graduate Theses and Dissertations
Harmful Algal Blooms (HABs) are an increasing global concern for water management due to their increased frequency, distribution, and toxin production. In freshwaters the growth of cyanobacteria (commonly known as blue-green algae), due to anthropogenic nutrient enrichment is the primary driver of HABS; these are often referred to as cyanoHABs. The management of cyanoHABs should be focused on in the watershed through best management and conservation practices or the physical, chemical and biomanipulation of the lake or reservoir that is experiencing these blooms. In this study, we examine the use of biochar as an option for the management or treatment …
On The Impact Of Inclination-Dependent Attenuation On The Derived Star Formation Histories Of Disk Galaxies, Keith Doore
On The Impact Of Inclination-Dependent Attenuation On The Derived Star Formation Histories Of Disk Galaxies, Keith Doore
Graduate Theses and Dissertations
The physical properties of a galaxy (e.g., its star-formation history and dust content) regulate the distribution of light that is emitted by stars and attenuated by the interstellar gas and dust. This attenuation by dust can have a significant impact on the observed spectral energy distribution (SED) of a disk galaxy, especially when taking into account its viewing angle (i.e., inclination). For example, as the inclination angle of a galactic disk changes from face-on to edge-on (i.e., i = 0 deg to i = 90 deg), the proportion of light that is attenuated along the line of sight increases, due …
An Experimental Study Into Tholin's Solubility With Liquid Hydrocarbons On Titan, Katherine Dzurilla
An Experimental Study Into Tholin's Solubility With Liquid Hydrocarbons On Titan, Katherine Dzurilla
Graduate Theses and Dissertations
Titan’s production of organics in its atmosphere and the liquid hydrocarbon lakes present on its surface make it a prime target for astrobiologists. Many previous studies on laboratory analogs of these organics, called "tholins", have found amino acids, nitriles, and other building blocks necessary for life. The potential solubility of tholins in the lakes of Titan presents an opportunity to create physical and chemical changes within the organics. While the lakes of Titan are primarily comprised of nonpolar compounds (methane and ethane), many predict that very small amounts of polar hydrocarbons are also present. To better understand these processes, researchers …
Exploring Ferroelectric Phenomena In Batio3, Linbo3, And Liznsb: From Extended Oxygen Vacancies To Tri-Stable Polarization And Giant Hyperferroelectricity, Shaohui Qiu
Graduate Theses and Dissertations
This dissertation presents three projects that investigate the complex phenomena of ferroelectricity under different conditions in BaTiO3, LiNbO3, and LiZnSb using first-principles density functional calculations. Extended defects in ferroelectric solids play a crucial role in reducing the lifetime and performance of ferroelectric devices by causing fatigue, domain pinning, and aging. Thus, understanding their impact is of critical importance for the development of reliable and high-performance ferroelectric devices. In addition, hyperferroelectricity is an intriguing phenomenon that has attracted much attention in recent years. Despite the existence of depolarization field, spontaneous polarization persists under an open-circuit boundary condition (OCBC), making hyperferroelectric materials …
Insights Into Star Formation And Agn Activity In Protocluster Environments From Morphological Studies And Sed Fitting, Erik B. Monson
Insights Into Star Formation And Agn Activity In Protocluster Environments From Morphological Studies And Sed Fitting, Erik B. Monson
Graduate Theses and Dissertations
In this dissertation I present work done from 2018-2023 to investigate the growth of galaxies and supermassive black holes (SMBH) in high redshift overdensities (protoclusters) by studying the star-forming galaxy and active galactic nucleus (AGN) population in the SSA22 protocluster. I examined possible environmental sources of the enhanced star formation and AGN activity in the z = 3.09 SSA22 protocluster using Hubble WFC3 ∼ 1.6 μm observations of the SSA22 field, including new observations centered on eight X-ray selected protocluster AGN. To investigate the role of mergers in the observed AGN and star formation enhancement, quantitative and visual morphological classifications …
Understanding And Tuning Magnetism In Van Der Waals Magnetic Compounds, Rabindra Basnet
Understanding And Tuning Magnetism In Van Der Waals Magnetic Compounds, Rabindra Basnet
Graduate Theses and Dissertations
The recently discovered two-dimensional (2D) magnetism has attracted intensive attention due to possible magnetic phenomenon arising from 2D magnetism and their promising potential for spintronics applications. The advances in 2D magnetism have motivated the study of layered magnetic materials, and further enhanced our ability to tune their magnetic properties. Among various layered magnets, tunable magnetism has been widely investigated in metal thiophosphates MPX3. It is a class of magnetic van der Waals (vdW) materials with antiferromagnetic ordering persisting down to atomically thin limit. Their magnetism originates from the localized moments due to 3d electrons in transition metal ions. So, their …
Improving Classification In Single And Multi-View Images, Hadi Kanaan Hadi Salman
Improving Classification In Single And Multi-View Images, Hadi Kanaan Hadi Salman
Graduate Theses and Dissertations
Image classification is a sub-field of computer vision that focuses on identifying objects within digital images. In order to improve image classification we must address the following areas of improvement: 1) Single and Multi-View data quality using data pre-processing techniques. 2) Enhancing deep feature learning to extract alternative representation of the data. 3) Improving decision or prediction of labels. This dissertation presents a series of four published papers that explore different improvements of image classification. In our first paper, we explore the Siamese network architecture to create a Convolution Neural Network based similarity metric. We learn the priority features that …
First-Principal Investigations Of The Electronic, Magnetic, And Thermoelectric Properties Of Crtirhal Quaternary Heusler Alloy, Shuruq Alsayegh
First-Principal Investigations Of The Electronic, Magnetic, And Thermoelectric Properties Of Crtirhal Quaternary Heusler Alloy, Shuruq Alsayegh
Graduate Theses and Dissertations
Density functional theory calculations are performed to investigate the electrical electronic, magnetic, and thermoelectric properties of CrTiRhAl quaternary Heusler alloy (QHA). The type-I atomic configuration is found to be the most stable structure of this alloy. The CrTiRhAl QHA exhibits a half-metallic ferromagnetic structure with a narrow band gap at one spin channel (semiconductor), and a metallic behavior at the other spin channel. This corresponds to a 100% spin-polarization, making it ideal for potential spintronic applications. Applying the semi-classical Boltzmann theory, the Seebeck coefficient, electrical conductivity, and electronic thermal conductivity of CrTiRhAl alloy were calculated. The predicted figure of merit …
An Age, Size, And Climate Response Study Of Old Growth Shortleaf Pine In The Mccurtain County Wilderness Area, Oklahoma, Nicholas Cancalosi-Dean
An Age, Size, And Climate Response Study Of Old Growth Shortleaf Pine In The Mccurtain County Wilderness Area, Oklahoma, Nicholas Cancalosi-Dean
Graduate Theses and Dissertations
Increment cores were extracted from 483 trees distributed over 21 semi-randomly sampled 0.1-hectare plots on three distinct landscape positions in the McCurtain County Wilderness Area (MCWA), a 57 square kilometer tract of uncut shortleaf pine in southeastern Oklahoma. Forty additional cores were taken off plot from older-appearing trees. All sampled trees were shortleaf pine (Pinus echinata) with a diameter at breast height (DBH) of at least 10 cm. Hardwoods were not included in the size and age analyses. The study site chosen for the sampling was made up of four parallel east-west trending ridges near North Linson Creek, making up …
Effects Of Land Use On Soil Microbial Communities In Tropical Montane Forests Of Malaysian Borneo, Yang Kai Tang
Effects Of Land Use On Soil Microbial Communities In Tropical Montane Forests Of Malaysian Borneo, Yang Kai Tang
Graduate Theses and Dissertations
Land use, such as logging and forest conversion to agriculture, can modify soil physicochemical and biological properties, and affect soil health. To understand how land use change can impact soil properties and canopy structure, we used a land use gradient in Malaysian Borneo consisting of six sites, including old growth forests, mixed forests, and agriculture fields. Specifically, we aimed to answer the following questions: (1) How do soil physicochemical properties vary across land use types? (2) Does bacterial diversity and composition vary across different land use types? (3) Does fungal diversity and composition vary across different land use types? We …
The Terroir Of Swiss Cheese: A Temporal And Geomorphological Investigation Of The Martian Co2 Sublimation Pits, Racine D. Cleveland
The Terroir Of Swiss Cheese: A Temporal And Geomorphological Investigation Of The Martian Co2 Sublimation Pits, Racine D. Cleveland
Graduate Theses and Dissertations
Observations by NASA Mars Global Surveyor showed evidence of rough topography on the South Pole of Mars. The topography is the result of CO2 sublimation processes that occur through the changing seasons on the red planet. These sublimation areas are known to scientists as Swiss Cheese Features (SCF). SCF are erosional degradation pits that have been studied for over two decades. Studies show that these SCF increase in area over time, but these values are collected by hand on a per feature basis. Models for the pit evolution have also played a part in understanding these SCF. This work is …
Achieving Causal Fairness In Recommendation, Wen Huang
Achieving Causal Fairness In Recommendation, Wen Huang
Graduate Theses and Dissertations
Recommender systems provide personalized services for users seeking information and play an increasingly important role in online applications. While most research papers focus on inventing machine learning algorithms to fit user behavior data and maximizing predictive performance in recommendation, it is also very important to develop fairness-aware machine learning algorithms such that the decisions made by them are not only accurate but also meet desired fairness requirements. In personalized recommendation, although there are many works focusing on fairness and discrimination, how to achieve user-side fairness in bandit recommendation from a causal perspective still remains a challenging task. Besides, the deployed …
Asymptotic Properties And Separation Rates For Navier-Stokes Flows, Patrick Michael Phelps
Asymptotic Properties And Separation Rates For Navier-Stokes Flows, Patrick Michael Phelps
Graduate Theses and Dissertations
In this dissertation, we investigate asymptotic properties of local energy solutions to the Navier-Stokes equations and develop an application which controls the separation of non-unique solutions in this class. Specifically, we quantify the rate at which two, possibly unique solutions evolving from the same data may separate pointwise away from a singularity. This is motivated by recent results on non-uniqueness for forced and unforced Navier-Stokes and analytical and numerical evidence suggesting non-uniqueness in the Leray class. Our investigation begins with discretely self-similar solutions known to exist globally in time and to be regular outside a space-time paraboloid. We prove decay …
Evaluation Of Hydrogeochemical Characteristics Of San Joaquin, Tulare, And Mojave Aquifers, Southern California, Maedeh Hassanvand
Evaluation Of Hydrogeochemical Characteristics Of San Joaquin, Tulare, And Mojave Aquifers, Southern California, Maedeh Hassanvand
Graduate Theses and Dissertations
Before making attempts to enhance and manage the quality of water, a thorough understanding of these processes is necessary since the chemical quality of groundwater is impacted by a number of linked processes. This would be more important in arid and semiarid regions like the southern part of California where more rely on groundwater for agriculture and drinking water uses than the other states. As a result, fundamental knowledge of the governing processes of groundwater chemistry is required for effective water resource management. Thus, this study is primarily concerned with three aspects in Mojave, Tulare, and San Joaquin aquifers: The …
Effects Of Landscape And Yard Features On Mammals In Residential Yards In Northwest Arkansas, Emily Johansson
Effects Of Landscape And Yard Features On Mammals In Residential Yards In Northwest Arkansas, Emily Johansson
Graduate Theses and Dissertations
The human footprint is rapidly expanding, and wildlife habitat is continuously being converted to human residential properties. Most wildlife residing in developing areas are displaced to nearby undeveloped areas. However, some animals can coexist with humans and acquire the necessary resources (food, water, shelter) within the human environment. This may be particularly true when development is low intensity, as in suburban yards. Due to the wide variety in how homeowners utilize their yards, they can be considered individually managed “greenspaces.” These yards can provide a range of food (e.g., bird feeders, compost, gardens), water (bird baths and garden ponds), and …
Potential Control Of Invasive Mesquite Through Improving The Consumer’S Understanding Of Liquid Smoke Applications., Seth W. Ellsworth
Potential Control Of Invasive Mesquite Through Improving The Consumer’S Understanding Of Liquid Smoke Applications., Seth W. Ellsworth
Graduate Theses and Dissertations
Mesquite trees continue to invade forests and range lands in many countries across the world. The cost to remove these trees is staggering. In Texas, landowners spent $25 million over a 10- year period to clear 300,000 ha of mesquite trees, a fraction of the 22 million ha of Texas land affected by this invasion. Estimates are that the mesquite continues to negatively impact one to two percent of additional land in selected counties each year in Texas. However, the problem is not unique to Texas, but rather to the 44 species of mesquite trees, belonging to the genus Prosopis …