Digital Commons Network^™

Phase-Field Simulations Of The Precipitation Kinetics And Microstructure Development In Nickel-Based Superalloys, Caleb O. Yenusah

Theses and Dissertations

The continual research and development of nickel-based superalloys is driven by the global demand to improve efficiency and reduce emissions in the aerospace and power generation industries. Integrated Computational Material Engineering (ICME) is a valuable tool for reducing the cost, time, and resources necessary for the development and optimization of the mechanical properties of materials. In this work, an ICME approach for understanding the microstructure development and optimizing the mechanical properties in nickel-based superalloys is employed. Most nickel-based superalloys are precipitate strengthened by either the γ’ phase, γ” phase, or both. Therefore, understanding the precipitation kinetics and morphological evolution of …

Impact Of Row Spacing/Planting Pattern And Seed Size On Plant Development And Yield On Cotton (Gossypium Hirsutum L.)., Steven Dale Hall

Theses and Dissertations

There is renewed interest in cotton performance grown using various row spacings and plantings patterns in the Midsouth. Cotton seed size has been reduced compared to sixty years ago. Planting smaller seeds is concerning due to having less energy for emergence as well as complicating the ginning process. Two row spacings, two planting patterns, and two cotton varieties were evaluated over eight site years from 2019-2020. The solid planting pattern produced a higher yield on a land area basis. In addition, two varieties, each with three seed counts, were planted at three seeding rates and evaluated over six site years …

Borderline Personality Disorder And Suicide Risk: The Role Of Emotional Vulnerability, Parental Invalidation, And Adverse Childhood Experiences, Chandler Jayne Mcdaniel

Theses and Dissertations

Childhood adversity is linked with a variety of negative outcomes including suicide attempts and personality disorders, most commonly Borderline Personality Disorder (BPD). A core feature of BPD, emotion dysregulation is often reported following early childhood adversity and contributes to both suicidal ideation and attempts. One explanation for the development of emotion dysregulation within BPD, is the biosocial model, which states that there must be an interaction between childhood emotional vulnerability and parental invalidation. Recent literature suggests that this interaction may not be necessary. Thus, the current study extended previous literature by examining childhood risk factors (i.e., ACES, parental invalidation, and …

Assessment Of Retention Trends In The College Of Agriculture And Life Sciences To Determine Possible Internal Recruitment Efforts For Poultry Science Departments And Enhance University Retention, Peyton Alyssa Taylor

Theses and Dissertations

With only six poultry degree granting universities, producing a slim number of graduates each year, poses a challenge for the industry. There may be potential areas for internal recruitment within Colleges of Agriculture and Life Sciences (CALS). In study 1, an evaluation of Mississippi State University’s CALS retention trends determined that Biochemistry (BCH) and Animal Science (AS) have the lowest retention rates. Study 2 compared all six poultry degree granting universities’ CALS retention rates, with AS continuously having one of the lowest retention rates. Lastly, Study 3 surveyed undergraduates, advisors, and faculty showing students having an interest in poultry while …

Studies On The Impact Of An Insect Growth Regulator And Host Plant On Reproductive Physiology Of Lygus Lineolaris, James Houston Chance Anderson

Theses and Dissertations

The tarnished plant bug, Lygus lineolaris, is an economically important polyphagous pest with a broad host range. With occurrence of insecticide resistance, strategies to limit its ability to reproduce, which would curb population growth, are becoming increasingly more valuable. Strategies toward this goal include the application of insect growth regulators (IGRs) and utilization of resistant cotton lines. This thesis summarizes experiments that elucidate the physiological underpinnings of the mode of action of novaluron, an IGR, and a cotton chromosome substitution (CS) line on the reproductive physiology of L. lineolaris. Investigations reported herein indicate that novaluron inhibits oviposition by …

Individual Differences In Structure Learning, Philip Newlin

Theses and Dissertations

Humans have a tendency to impute structure spontaneously even in simple learning tasks, however the way they approach structure learning can vary drastically. The present study sought to determine why individuals learn structure differently. One hypothesized explanation for differences in structure learning is individual differences in cognitive control. Cognitive control allows individuals to maintain representations of a task and may interact with reinforcement learning systems. It was expected that individual differences in propensity to apply cognitive control, which shares component processes with hierarchical reinforcement learning, may explain how individuals learn structure differently in a simple structure learning task. Results showed …

The Inauguration Of President Laurie A. Carter, Lawrence University

Presidential Addresses

The Lawrence University Board of Trustees, along with the Lawrence University Alumni Association and Lawrence University Community Council, are excited to announce the Inauguration of Laurie A. Carter as the 17th President of Lawrence University.

Laurie A. Carter joined the Lawrence community as its 17th president on July 1, 2021, bringing with her more than 25 years of leadership experience in higher education.

Structural Sizing Of Post-Buckled Thermally Stressed Stiffened Panels, Walid Arsalane

Theses and Dissertations

Design of thermoelastic structures can be highly counterintuitive due to design-dependent loading and impact of geometric nonlinearity on the structural response. Thermal loading generates in-plane stresses in a restrained panel, but the presence of geometric nonlinearity creates an extension-bending coupling that results in considerable transverse displacement and variation in stiffness characteristics, and these affects are enhanced in post-bucking regimes. Herein a methodology for structural sizing of thermally stressed post-buckled stiffened panels is proposed and applied for optimization of the blade and hat stiffeners using a gradient-based optimizer. The stiffened panels are subjected to uniform thermal loading and optimized for minimum …

Transformer Fault Event Detection And Classification Using Pmus, Yadunandan Paudel

Theses and Dissertations

Transformer is one of the most reliable components in an electric power system, however its failure has huge opportunity costs for an electric utility. In this work, we detect transformer electrical faults promptly and accurately classify the fault types using voltage/current data from Phasor Measurement Units. Our work can also eliminate uncertainties which are inherent in traditional transformer fault diagnostic techniques like dissolved gas analysis. In this thesis, first, possible causes of transformer failures are discussed, and four common transformer electrical faults are identified. Second, a comprehensive simulation model for electrical faults is developed. Third, fast and efficient abrupt change …

Migration Ecology Of American White Pelicans: Circannual Movement, Geographic Range, And Annual Survival, Ryo Ogawa

Theses and Dissertations

Responses of migratory birds to seasonal climate and long-term environmental changes have been a central theme of avian migration ecology. Atmospheric conditions (e.g., winds and thermals), climate, and land cover and land use (LCLU) are major factors influencing the flights of soaring birds. Soaring American White Pelicans (Pelecanus erythrorhynchos) (hereafter, AWPEs) migrate between the subtropical Gulf of Mexico (GOM) and the temperate Northern Great Plains. American White Pelicans are also economically important piscivorous birds, causing enormous damages to the commercial Channel Catfish (Ictalurus punctatus) aquaculture in the Southeastern US. My studies aimed to evaluate the effects …

Assessing Priority Bird Response To Open Pine Management In Eastern Mississippi, Holly Marie Todaro

Theses and Dissertations

Fire suppression, combined with lack of forest thinning and short-rotation, monodominant management, has drastically altered the landscape in the southeastern U.S., leading to the loss of open pine ecosystems and associated avian species. Management of open pine ecosystems is a common practice; yet, there remains uncertainty regarding how vegetation structure impacts priority species. Using empirical data, I assessed changes in species abundance and associated vegetation characteristics before and after management. I also sought to identify vegetation characteristics that influence home range establishment and microhabitat selection of Bachman’s Sparrows. Priority species were negatively associated with hardwood midstory and abundance per site …

Analysis And Characterization Of The Volatile Compounds Associated With The Wooden Breast Condition, Hunter Hessler

Theses and Dissertations

In 2013, the wooden breast defect in broiler breast meat was characterized by hardened and pale areas at both the caudal and cranial regions of the breast. The objective of this study was to determine the flavor differences between severe woody and normal breast meat in both breast and patties using gas chromatography-mass spectrometry, gas chromatography-olfactometry, and sensory descriptive analysis. Forty-eight individual volatile flavor compounds were identified in both the ground and whole breast chicken samples including aldehydes, ketones, and other functional groups. Minimal differences existed in the volatile fraction of normal and severe woody breast meat. In contrast, woody …

Optimized Selenium Status, Gut Microbiota, And Type 2 Diabetes, Ying-Chen Huang

Theses and Dissertations

We have previously demonstrated that long-term dietary Se deficiency in old Terc^-/- mice with humanized telomeres induces type-2 diabetes and exacerbates age-dependent increases in the abundance of A. muciniphila and Lachnospiraceae, which are related to obesity and metabolic syndromes. The objectives of this dissertation are: 1) to determine the minimum intake of Se required for type 2 diabetes prevention in middle-aged mice; 2) to evaluate the efficacy of A. muciniphila and R. torques (a Lachnospiraceae family member) to intervene dietary Se deficiency-induced type 2 diabetes and the underlying mechanisms; 3) to assess sex differences in the responses to …

The Effects Of Ecological Simulation For Ground Vehicle Mobility Forecasting, Christopher R. Hudson

Theses and Dissertations

Unmanned ground vehicles (UGV) are being explored for use in military domains. Military UGVs operate in complex off-road environments. Vehicle mobility forecasting plays an important role in understanding how and where a vehicle can operate. Traditional mobility forecasting has been done using an analytical model known as the NATO Reference Mobility Model (NRMM). There has been a push to extend the forecasting capabilities of NRMM by integrating more simulation methods. Simulation enables the repeated testing of UGVs in scenarios that would be difficult or dangerous to study in real world testing. To accurately capture UGV performance in simulation, the operating …

Evaluation Of Non-Labeled Herbicides In Cotton Production In Mississippi, Zaim Ugljic

Theses and Dissertations

Weed resistance has decreased the number of herbicides that provide effective weed control in cotton. Studies were conducted to determine weed control efficacy and crop safety in cotton with herbicides not currently labeled for use in the crop. Herbicides were applied at two different timings near Starkville and Brooksville, MS. Cotton injury following application of ametryn, bentazon, florpyrauxifen-benzyl, topramezone and tolpyralate at the 3-5 or the 8-10 node growth stage ranged from 24 to 43% and 15 to 51%, respectively, up to 56 days after application. Except for bentazon, applying non-labeled herbicides to cotton at the 3-5 or 8-10 node …

Data-Driven Sparse Computational Imaging With Deep Learning, Robiulhossain Mdrafi

Theses and Dissertations

Typically, inverse imaging problems deal with the reconstruction of images from the sensor measurements where sensors can take form of any imaging modality like camera, radar, hyperspectral or medical imaging systems. In an ideal scenario, we can reconstruct the images via applying an inversion procedure from these sensors’ measurements, but practical applications have several challenges: the measurement acquisition process is heavily corrupted by the noise, the forward model is not exactly known, and non-linearities or unknown physics of the data acquisition play roles. Hence, perfect inverse function is not exactly known for immaculate image reconstruction. To this end, in this …

Spatial-Spectral Analysis In Dimensionality Reduction For Hyperspectral Image Classification, Chiranjibi Shah

Theses and Dissertations

This dissertation develops new algorithms with different techniques in utilizing spatial and spectral information for hyperspectral image classification. It is necessary to perform spatial and spectral analysis and conduct dimensionality reduction (DR) for effective feature extraction, because hyperspectral imagery consists of a large number of spatial pixels along with hundreds of spectral dimensions.

In the first proposed method, it employs spatial-aware collaboration-competition preserving graph embedding by imposing a spatial regularization term along with Tikhonov regularization in the objective function for DR of hyperspectral imagery. Moreover, Collaboration representation (CR) is an efficient classifier but without using spatial information. Thus, structure-aware collaborative …

Developing A Model Of Driver Performance, Situation Awareness, And Cognitive Load Considering Different Levels Of Partial Vehicle Autonomy, Jessie E. Cossitt

Theses and Dissertations

To fully utilize the abilities of current autonomous vehicles, it is necessary to understand the interactions between vehicles and their operators. Since the current state of the art of autonomous vehicles is partial autonomy that requires operators to perform parts of the driving task and be alert and ready to take over full control of the vehicle, it is necessary to know how operators' abilities are impacted by the amount of autonomy present in the system. Autonomous systems have known effects on performance, cognitive load, and situation awareness, but little is known about how these effects change in relation to …

Comparison Of Abdominal Computed Tomography To Ultrasound In The Diagnosis Of Canine Biliary Disease Manifesting As Acute Abdominal Signs, Shanna Christine Marroquin

Theses and Dissertations

Biliary diseases are uncommon, potentially fatal causes of acute abdomen in dogs. Little information is present comparing the performance of computed tomography (CT) to ultrasound in identifying canine biliary pathology. Thirty-five client-owned dogs presenting for acute abdomen signs received an abdominal ultrasound and contrast-enhanced abdominal CT. Two authors reviewed the randomized, anonymized CT and ultrasound studies. Twenty-eight dogs had biliary pathology and seven dogs serving as controls had no evidence of biliary disease. The final diagnoses of patients with biliary pathology included cholelithiasis, gallbladder mucoceles, cholangiohepatitis/cholangitis, extrahepatic biliary obstruction, gallbladder wall edema, gallbladder wall mass, and cystic mucosal hyperplasia. Computed …

A Novel Chebyshev Wavelet Method For Solving Fractional-Order Optimal Control Problems, Ghodsieh Ghanbari

Theses and Dissertations

This thesis presents a numerical approach based on generalized fractional-order Chebyshev wavelets for solving fractional-order optimal control problems. The exact value of the Riemann– Liouville fractional integral operator of the generalized fractional-order Chebyshev wavelets is computed by applying the regularized beta function. We apply the given wavelets, the exact formula, and the collocation method to transform the studied problem into a new optimization problem. The convergence analysis of the proposed method is provided. The present method is extended for solving fractional-order, distributed-order, and variable-order optimal control problems. Illustrative examples are considered to show the advantage of this method in comparison …

A Novel Method For Sensitivity Analysis Of Time-Averaged Chaotic System Solutions, Christian A. Spencer-Coker

Theses and Dissertations

The direct and adjoint methods are to linearize the time-averaged solution of bounded dynamical systems about one or more design parameters. Hence, such methods are one way to obtain the gradient necessary in locally optimizing a dynamical system’s time-averaged behavior over those design parameters. However, when analyzing nonlinear systems whose solutions exhibit chaos, standard direct and adjoint sensitivity methods yield meaningless results due to time-local instability of the system. The present work proposes a new method of solving the direct and adjoint linear systems in time, then tests that method’s ability to solve instances of the Lorenz system that exhibit …

Consumer Attitudes And Perceptions Towards The Use Of Reclaimed Wood, Mia Craig

Theses and Dissertations

Reclaimed wood is material salvaged from old, abandoned buildings that offers sustainable living to communities. There have been previous studies on reclaimed wood, but a limited amount linking reclaimed wood to consumerism. In August 2021, an online survey was conducted to gauge consumers’ knowledge of the industry and attitudes on reclaimed wood practices. Consumers are U.S. citizens 18 years of age or older. Study results indicate that respondents have little knowledge regarding reclaimed wood. Of the 1,516 respondents, 44% seem knowledgeable of reclaimed wood. Most respondents are not aware that reclaimed wood is a separate industry. Respondents believe there should …

Characterization Of Quaternary Stratigraphy In The Mississippi Sound To Evaluate The Influence Of Geologic Heterogeneity On Submarine Groundwater Transport And Discharge, Zachary Peoples

Theses and Dissertations

Submarine Groundwater Discharge (SGD) through seafloor sediments is gaining recognition as an important component of coastal water quality. Stratigraphic features creating geologic heterogeneity, such as incised paleochannels, may influence preferential pathways for SGD. The central Mississippi Sound is underlain by paleochannels that were incised into Pleistocene sediments while the area was subaerially exposed during the last glacial maximum and are now buried by transgressive Holocene deposits. In this thesis, newly collected chirp, previously published seismic reflection, and sediment core data are used to characterize the three-dimensional structure of the Holocene-Pleistocene contact. Results indicate that Pleistocene paleochannels cross-cut the study area, …

Exploring The Impact Of End-User Engagement On The Diffusion And Adoption Of A Climate Resilience Tool In The Gulf Of Mexico, Renee C. Collini

Theses and Dissertations

Climate change-related hazards negatively impact ecosystems, economies, and quality of life. Significant resources have been invested in data collection and research with the goal of enhanced understanding and capacity to predict future conditions in order to mitigate or adapt to intensifying hazard risk. The expansive production of climate science has generated a necessary complimentary enterprise dedicated to enhancing decision-makers’ understanding of and access to climate science as it is essential for future societal and ecological well-being. Though the aim of these many tools is to support resilient decision-making in the face of climate change, professionals report an underutilization of climate …

Incorporating Spatial Relationship Information In Signal-To-Text Processing, Jeremy Elon Davis

Theses and Dissertations

This dissertation outlines the development of a signal-to-text system that incorporates spatial relationship information to generate scene descriptions. Existing signal-to-text systems generate accurate descriptions in regards to information contained in an image. However, to date, no signalto- text system incorporates spatial relationship information. A survey of related work in the fields of object detection, signal-to-text, and spatial relationships in images is presented first. Three methodologies followed by evaluations were conducted in order to create the signal-to-text system: 1) generation of object localization results from a set of input images, 2) derivation of Level One Summaries from an input image, and …

An Investigation Of Sea-Breeze Driven Convection Along The Northern Gulf Coast, Caitlin Ford

Theses and Dissertations

Although sea-breezes frequently initiate convection, it is oftentimes challenging to forecast the precise location of storm development. This research examines temporal and spatial characteristics of sea-breeze driven convection and environmental conditions that support convective or non-convective sea-breeze days along the Northern Gulf Coast. Base reflectivity products were used to identify the initial time of convection (values greater than 30 dBZs) along the sea-breeze front. It was found that convective sea-breezes initiated earlier in the day compared to non-convective sea-breezes. Mapping convective cells in ArcGIS revealed favored locations of thunderstorm development including the southeastern cusp of Mobile County, Alabama and convex …

The Effects Of Short-Term Sea Level Rise On Vegetation Communities In Coastal Mississippi, Brianna Michelle Andrews

Theses and Dissertations

Salt marshes are important habitats that provide many ecosystem services, but they are susceptible to the impacts of sea level rise (SLR), often resulting in emergent vegetation loss. In areas with enough sediment input, marshes can keep pace with SLR by gaining elevation or through upland migration. However, salt marshes in areas with limited sediment input, such as the Grand Bay National Estuarine Research Reserve, often cannot keep pace with sea level rise. Additionally, the rate of SLR is increasing making it more difficult for marshes to keep pace. To assess the short-term response of marsh vegetation to sea level …

Evaluating Cover Crops To Determine The Best Management Practice For The Suppression Of Tall Waterhemp And Italian Ryegrass, Samuel R. Reeves

Theses and Dissertations

To combat herbicide resistance among weeds, non-herbicide methods of control, such as cover crops, are becoming widely adapted. Experiments were conducted to determine how to effectively establish and manage cover crops in order to suppress tall waterhemp and Italian ryegrass and to assess their overall impact on soybean growth and yield. Various cover crop establishment methods were evaluated, and it was determined that interseeding at the R7 growth stage of soybean was the least effective method for proper cover crop establishment. Biomass data demonstrated that interseeding created the least amountof cover crop biomass, with no differences found among the other …

Mechanical Property Relationships Of Cement Or Lime Stabilized Soils Throughout A Pavement's Life, Leigh E.W. Ayers

Theses and Dissertations

Soil-cement is an integral part of pavement design, especially in areas that are aggregate deprived, such as Mississippi. Current designs are reliant on the relationship of unconfined compressive strength (UCS) to other mechanical properties. The other properties discussed in this dissertation are Modulus of Elasticity (E), Indirect Tensile Strength (St), and Modulus of Rupture (MOR). This dissertation includes a comprehensive review of past design methods and mechanical property relationships. While some mechanical property relationships were shown to be well understood (i.e. St to UCS), others were not as accurate, especially for the later life mechanical properties (i.e. MOR to UCS …

Non-Classroom Involvement Among Rural Community College Students: An Application Of Tinto And Astin’S Models, William Johnson Bowlin

Theses and Dissertations

Participation in non-classroom activities has been documented to extend the intellectual, social, and psychosocial outcomes of the college experience. However, the benefits of non-classroom activities are often difficult to quantify due their voluntary nature, with findings mostly related to students within four-year institutions. The purpose of this study was to determine whether rural community college full-time freshman students who participate in non-classroom activities differ from nonparticipants with regard to self-identified values of academic integration, social integration, degree commitment, collegiate stress, and institutional commitment. These five factors have been demonstrated to influence student persistence and were adopted from Davidson et al.’s …