Digital Commons Network^™

Physically Motivated Internal State Variable Form Of A Higher Order Damage Model For Engineering Materials With Uncertainty, Kiran N. Solanki

Theses and Dissertations

any experiments demonstrate that isotropic ductile materials used in engineering applications develop anisotropic damage and shows significant variation in elongation to failure. This anisotropic damage is manifest by material microstructural heterogeneities and morphological changes during deformation. The variation in elongation to the failure could be attributed to the uncertainties in the material microstructure and loading conditions. To study this deformation induced anisotropy arising from the initial material heterogeneities, we first performed uncertainty analysis using current form on an internal state variable plasticity and isotropic damage model (Bammann, 1984; Horstemeyer, 2001) to quantify the effect due to variations in material microstructure …

Protocols For Preconditioning Of Patellar Tendon For Anterior Cruciate Ligament Reconstruction, Richard Lee Crawford

Theses and Dissertations

The ACL is one of the major ligaments in the knee connecting the femur to the tibia which provides stability by resisting shear in sagittal plane. ACL tears occur in 1 out of 3000, and due to inability to heal, reconstructive surgeries are performed at a rate of 200,000/year. Final graft fixation tension during surgery has been shown to wane due to stress-relaxation which has been correlated with negative clinical outcomes. Therefore, preconditioning, which currently is an isometric load (88N), is performed to remove stress-relaxation after the final tension has been applied in vivo. Three preconditioning protocols, creep, stress relaxation, …

Quantifying Cognitive Workload And Defining Training Time Requirements Using Thermography, Jihun Kang

Theses and Dissertations

Effective mental workload measurement is critical because mental workload significantly affects human performance. A non-invasive and objective workload measurement tool is needed to overcome limitations of current mental workload measures. Further, training/learning increases mental workload during skill or knowledge acquisition, followed by a decreased mental workload, though sufficient training times are unknown. The objectives of this study were to: (1) investigate the efficacy of using thermography as a non-contact physiological measure to quantify mental workload, (2) quantify and describe the relationship between mental workload and learning/training, and, (3) introduce a method to determine a sufficient training time and an optimal …

Low-Temperature Halo-Carbon Homoepitaxial Growth Of 4h-Sic, Huang-De Hennessy Lin

Theses and Dissertations

New halo-carbon precursor, CH3Cl, is used in this work to replace the traditional C3H8 gas as a carbon precursor for the homoepitaxial growth of 4H-SiC. The traditional SiH4-C3H8-H2 systems require high growth temperatures to enable the desirable steplow growth for high-quality epilayers. A well known problem of the regular-temperature growth is the homogeneous gas-phase nucleation caused by SiH4 decomposition. However, the degree of Si cluster formation in the gas phase and its influence on our low-temperature epitaxial growth was unknown prior to this work. Growth at temperatures below 1400°C was demonstrated previously only for a limited range of substrate surface …

The Relationship Between The Freshman Academy And Student Academic Success At Morristown-Hamblen High School East., Patricia Ann Sigler

Electronic Theses and Dissertations

The purpose of this study was to determine whether or not a significant relationship exists between the implementation of the Morristown-Hamblen High School East (MHHSE) Freshman Academy, student academic achievement, and the high school graduation rate at MHHSE.

The testing variables included GPA, attendance, number of core course failures, number of discipline referrals, English I End-of-Course test scores, and graduation rate. Grouping variables included 8^th grade (pretreatment) and 9^th grade (posttreatment) groups, preacademy and postacademy groups, socioeconomic status, and gender. Ten faculty members of the MHHSE Freshman Academy were interviewed to ascertain their perceptions about the smaller learning …

A Study Of Nontraditional Undergraduate Students At The University Of Memphis., Linda G. Wood-Wyatt

Electronic Theses and Dissertations

This study examined nontraditional student engagement into the collegiate environment on the University of Memphis (U of M) campus, specifically services and programs in the University College. The sample surveyed included 4 nontraditional undergraduate students, 1 from each grade level, aged 25 years or older. The 4 nontraditional undergraduate study participants were admitted and enrolled at the U of M. Additionally, there was 1 alumnae member included in the study.

The study employed the use of multiple forms of data collection including interviews, personal and focus group, journaling, life stories, and an online campus climate survey. In order to analyze …

The Wood Supply System Of The Eastern United States: An Analysis Of The Socioeconomic Impacts On Local And Regional Value Chains, Clayton Bruce Altizer

Theses and Dissertations

The wood supply system is a dynamic and complex structure. Traditionally, key components of the system have been treated as stand-alone entities with very little regard to the performance of the overall system. The central component, the logging contractor, is usually viewed as a service provider and largely ignored. A value chain approach is an excellent tool to examine the primary stakeholders’ contributions to the wood supply system. The value chain for forestry usually extends completely across the physical and political landscape, reaching into the most geographically and economically remote locations. A conceptual model was developed depicting the wood supply …

Exploring Changes In Nascar-Related Titles In The New York Times And The Johnson City Press., Wesley Michael Ramey

Electronic Theses and Dissertations

NASCAR has become one of America's fastest growing spectator sports, and corporate sponsors have played an important part in this upsurge in popularity. Race teams, drivers, and sanctioning bodies use the income that sponsors provide to operate at NASCAR events. This study provides an analysis of how corporate sponsorships have changed the way that NASCAR is presented in print journalism. Using Burke's method of indexing, NASCAR-related titles in the New York Times and the Johnson City Press from 1950 to present day are analyzed. The analysis reveals not only a steady increase in the number of NASCAR-related titles, but 4 …

Faculty Perceptions About Instructional Technology In Eight Community Colleges In The Tennessee Board Of Regents Higher Education System., Nicole Cardwell-Hampton

Electronic Theses and Dissertations

The purpose of this study was to examine faculty members' perception of the status of technology support and services, their attitudes towards the incorporation of technology in general and with specific applications, and the barriers they perceive to technology use. Additionally, the study focused on the association among the predictor variables of faculty members' gender, age, professional status, years of higher education teaching experience, and tenure versus nontenure status with their degree of technology use.

An online survey was designed to collect data to address the research questions in the study. The survey consisted of 44 questions, including areas for …

The Effect Of Policy And Land Use Change On Water Quality In A Coastal Watershed City: An Analysis Of Covington, Louisiana, Kenneth Tyler Langley

Theses and Dissertations

There is currently a great need to expand the understanding of land use policy’s impact on water quality. The purpose of this thesis is to examine local policy in place in Covington, Louisiana in order to find out if it is having an impact on land use, which then has an impact on water quality. Methods used included reclassification of land use categories within a Geographical Information System and analysis of changes in the city over a four year period. Policy was assessed using a pre-existing evaluation method from The Center for Watershed Protection as well as by a more …

On A Slow Boat To Democracy: The Democratization Of Hong Kong And The Factors Hindering It, James Clapper

Theses and Dissertations

This study analyzes political, cultural, and social factors that influence democratization using Hong Kong as a case study. Hong Kong is a transitional society which provides a unique set of political and social characteristics for which to study democratic transition. Additionally, reports of political repression from the 2004 Legislative Council election have possibly created a crisis for the democratization process. Drawing from existing literature in theories of democratization, political repression and Hong Kong politics several hypotheses were developed. It was hypothesized that unchecked hegemonic deterrence, antidemocratic elites, and a weak political culture have contributed to a lack of democratization. Furthermore, …

Molecular And Biochemical Analysis Of Water Stress Induced Responses In Grape, Ramesh Katam

Theses and Dissertations

Water stress affects vine productivity, disease tolerance, and enological characteristics of grape. Florida Hybrid Bunch grape are developed through hybridization of local grape spp with Vitis vinifera. These cultivars are mostly grown in southeast region of United States. Water deficit conditions resulted due to failure of rains in the region has developed concern among Florida grape growers to increase water use efficiency of grape. The goal of this research is to identify genes and proteins differentially expressed in response to water stress and to correlate these changes with enological characteristics. Investigating transcripts and proteins will allow us to correlate them …

Molecular Dynamics Simulations Of Metals, Bohumir Jelinek

Theses and Dissertations

This dissertation describes the development and testing of modified embedded atom method (MEAM) interatomic potentials for Al, Si, Mg, Cu, Fe, and their alloys, with primary concentration on Mg-Al system. We performed the density functional theory (DFT) based ab initio calculations to determine the structural and elastic properties of element pairs that are impractical to obtain from experimental measurements. Specifically, we estimated the cohesive energy, equilibrium atomic volume, bulk modulus, and elastic moduli of every element pair in the NaCl reference structure. Based on the results of DFT calculations, MEAM parameters for each element pair were constructed. We extensively tested …

Guest Intercalation Into Metal Halide Inorganic-Organic Layered Perovskite Hybrid Solids And Hydrothermal Synthesis Of Tin Oxide Spheres, Nilantha Bandara

Theses and Dissertations

The work presented in this thesis is divided into two research areas. In part I, the synthesis and guest intercalation of inorganic-organic metal halide ammonium layered perovskites is discussed. Comparisons are made between the solid matrix before and after the intercalations, and all solids are characterized using thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD). In part II, “templateree” hydrothermal synthesis of tin oxide spheres in the presence of different ortho-substituted anilines is discussed. The aim is to determine whether there are differences in the structures, shapes and surface morphology of the tin oxide spheres that correspond to the identity/shape …

Fabrication Of Aluminum Matrix Particulate Composites By Compaction And Sintering, Wei Li

Theses and Dissertations

With the possession of extremely broad unique properties, particulate reinforced aluminum composites are very attractive in diverse applications. Aluminum matrix particulate composites are challenging to work with. A single pressing and sintering process was used to fabricate the reinforced aluminum composites in this study. The key advantage of this method is its comparative low expense. However, abrasive reinforcement powders can lead to shorter tool life. To study the fundamental wear mechanisms during the die compaction process, a new method was developed and combined with experiments to quantify tool wear. Automatic die compaction experiments and tribological experiments are employed in this …

Comparison Of State Estimation Algorithms Considering Phasor Measurement Units And Major And Minor Data Loss, Srinath Kamireddy

Theses and Dissertations

Various sensors distributed across different parts of the electric power grid provide measurements to the control center operator for situational awareness of the system. Voltage transformer, current transformer, relay and phasor measurement units (PMU) are types of sensors for power system monitoring. The utilities monitor the operating condition of their system by processing the measurements received from these various sensors using a state estimator. A state estimator refines these measurements, compensates for any lost data and provides a snapshot of the power system. The operator at the control center does further analysis using energy management system tools based on the …

Design, Construction, Inverse Kinematics, And Visualization Of Continuum Robots, Srinivas Neppalli

Theses and Dissertations

Continuum robots are the biologically inspired robots that mimic the behaviors of mammalian tongues, elephant trunks, and octopus arms. These robots feature a backboneless structure similar to their biological counterparts, such as termed muscular hydrostats. The drawbacks of two existing designs are examined and a new mechanical design that uses a single latex rubber tube as the central member is proposed, providing a design that is both simple and robust. Next, a novel verification procedure is applied to examine the validity of the proposed model in two different domains of applicability. A two-level electrical control scheme enables rapid prototyping and …

Effect Of Supercritical Water Treatment On The Composition Of Bio-Oil, Ananda Kumaran Sekar

Theses and Dissertations

The effect of supercritical water treatment on the composition of bio-oil was investigated. Preliminary studies were carried in batch mode using a bio-oil simulant. This bio-oil simulant was designed to mimic crude bio-oil by possessing the same functional groups as are found in crude bio-oil, but with reduced complexity. Experiments of this type allow to be gained of the reaction chemistry involved. These were then followed up by experiments using crude bio-oil. Critical process parameters for all these experiments were reaction time, bio-oil/water ratio, reaction temperature and pressure. One of the objectives of this work was to identify processing conditions …

Enhanced Models For Mixtures Of Fluids In Chemical Equilibrium At High Pressures, Pietro Gaiaschi

Theses and Dissertations

This thesis is concerned with the numerical simulation of mixtures of chemically reacting fluids at high pressures. Mixture rules are established, accommodating components that do not follow the thermally perfect Equation of State (EoS), and including formulas for the fugacities. Particular attention has been given to the species EoS originally developed by Hirschfelder, Buehler, McGee and Sutton. The Law of Mass Action that governs chemical equilibrium of mixtures of fluids is presented. The common assumption of neglecting fugacities contributions when calculating the equilibrium composition is assessed by comparing complete thermochemical predictions with those obtained by reduced models. For air mixtures …

Evaluation Of Chitosan And Collagen As Scaffolding For A Tissue Engineered Aortic Heart Valve, Steven Christopher Waller

Theses and Dissertations

Children born with congenital heart valve defects require open-heart surgery to implant an artificial replacement valve. These valves are unable to grow with the developing child and need replacing every 5 years. Tissue engineered heart valves, capable of growing with the patient, would alleviate the need for repeat surgery. I hypothesize chitosan and collagen possess advantageous qualities as scaffolding for a tissue engineered heart valve. This study evaluated chitosan and collagen hydrogels as potential scaffold materials. Chitosan scaffolds had suitable pore size/distribution and scaffold strength; however, they were unable to sustain cell attachment or viability. Collagen gels were assessed for …

Evaluation Of Erosional Forcings Of A Beach/Berm/Wetland System And Applicable Restoration Technologies, Jared Kyle Mckee

Theses and Dissertations

The purpose of this study was to evaluate the local and regional processes causing the shoreline recession of an eroding beach/berm/wetland system on the eastern shore of Mobile Bay. The analysis was then used to evaluate different technologies which could meld to create a holistic shoreline protection design to fortify the entire spectrum of the shoreline. Wind waves are the major erosional force causing a bi-directional, but southerly dominated, longshore transport and an erosional cross-shore transport during large wave events. Erosion mitigation technologies which promote ecological integrity are presented and include: oyster shell breakwaters, SAV establishment, intertidal grass plantings, and …

Development Of A Fish-Based Index Of Biotic Integrity For Oxbow Lakes Of The Yazoo River Basin, Mississippi, Nathan Aycock

Theses and Dissertations

Fish community data were used to develop an index of biotic integrity (IBI) to quantify habitat degradation in oxbow lakes of the Delta region of the Yazoo River Basin. Daytime boat electrofishing was used to sample the fish assemblage of 30 oxbow lakes during 2006-2007. We evaluated 70 candidate metrics based on their responses to measures of anthropogenic disturbance. Six metrics were retained for inclusion in the IBI: species richness, Shannon’s diversity (H’), average tolerance, and catch rates of buffalo, orangespotted sunfish, and litho-psammophilic spawners. The six IBI metrics showed strong multivariate relationships with measures of habitat degradation in a …

Development Of A Geovisual Analytics Environment Using Parallel Coordinates With Applications To Tropical Cyclone Trend Analysis, Chad A. Steed

Theses and Dissertations

A global transformation is being fueled by unprecedented growth in the quality, quantity, and number of different parameters in environmental data through the convergence of several technological advances in data collection and modeling. Although these data hold great potential for helping us understand many complex and, in some cases, life-threatening environmental processes, our ability to generate such data is far outpacing our ability to analyze it. In particular, conventional environmental data analysis tools are inadequate for coping with the size and complexity of these data. As a result, users are forced to reduce the problem in order to adapt to …

Development Of Three-Phase Continuation Power Flow For Voltage Stability Analysis Of Distribution Systems, Dina Khaniya

Theses and Dissertations

With distributed generation being introduced in the meshed distribution networks under increased loading conditions, maintaining the system voltage stability will become one of the major concerns. The conventional approach of repetitive power flow solutions fails to obtain the critical loading point as Jacobian becomes singular before maximum loading point. Continuation power flow methods, based on the predictor-corrector scheme, overcome this difficulty with the use of parameterization techniques. Continuation power flow tools, already developed for transmission systems, need to be extended to handle three phase unbalanced distribution systems. This research work contributes towards development of a robust and efficient three phase …

Educational Video Impact On College Student Knowledge, Opinions, And Referral Attitudes Regarding Attention-Deficit/Hyperactivity Disorder, Nichol Frances Pritchard

Theses and Dissertations

The interaction of osteoclasts and osteoblasts regulates bone density and the maintenance of osseointegration of implants. To investigate osteoblastic response to strain, rat osteosarcoma cells were cultured on titanium plates and subjected to one of three treatments: a neutral control (0 microstrain), tension (1000 microstrain), and compression (1000 microstrain). Treatments were applied via 4 point bending for fifteen minutes each day to a strain of 1mm/m at a sinusoidal frequency of 1Hz. Cells were measured for DNA as indicator of proliferation, alkaline phosphatase as indicator of phenotype and total protein and calcium deposition as indicators of matrix formation. Results indicated …

Development Of Corrective Actions For Higher Order Contingencies, Bharath Kumar Ravulapati

Theses and Dissertations

The importance of the electric power infrastructure has been exposed by several blackouts throughout the world in the last decade. These blackouts were caused mainly by physical vulnerabilities, human errors and natural disasters. The power grid is becoming more and more prone to outages which affect not only the power system network, but also other infrastructures and the society in several ways. Utilities generally operate with an (N-1) security level (no violations for single outage), and blackouts are generally caused by higher order contingencies. There is lack of effective methods and analysis tools to deal with higher order contingencies. Higher …

Development Of Overcurrent Relay Model And Power System Simulator Using National Instruments Devices In Real-Time, Sunil Kumar Palla

Theses and Dissertations

One of the major objectives at Mississippi State University’s Power and Energy Research Laboratory (PERL) is to develop an adaptive protective controller for Shipboard Power System (SPS) protection. This thesis work focuses on developing an overcurrent relay model in LabVIEW software and validating the developed model by conducting Hardware-in-the-Loop (HIL) tests with Real-Time Digital Simulator (RTDS) and commercial Schweitzer Engineering Laboratories (SEL)-351S directional over-current relay. Simulation results show that the developed relay model is quite flexible, efficient and can be used in real-time. Modeling efforts to establish a HIL platform using National Instruments devices have been presented here. This thesis …

Differential Relay Model Development And Validation Using Real Time Digital Simulator, Vamsi Krishna Vijapurapu

Theses and Dissertations

The protection system in a shipboard power system plays a vital role in detecting the fault conditions, isolating the faulted zone and preventing the fault propagation into other vital sections onboard the ship. The protection system should be able to remove faults and restore the service to all the vital loads rapidly. In order to design the protection system, preliminary hardware-in-the-loop testing is done using bus differential relay hardware and a Real Time Digital Simulator (RTDS). In this thesis work, based upon the functionalities of the relay hardware the software differential relay model is designed and simulated using the RSCAD …

Instructional Leadership: Perceptions Of Mississippi Career And Technical Education Administrators And Teachers, Leanne Freeman (Cheryl Leanne Freeman) Long

Theses and Dissertations

The purpose of this study was to determine perceptions of instructional leadership behaviors from Mississippi secondary career and technical education administrators and teachers in order to assist career and technical education administrators in becoming better instructional leaders. This research was conducted for the following purposes: (a) to determine which perceived instructional leadership behavior teachers consider most important, (b) to determine which perceived instructional leadership behavior administrators consider most important, (c) to determine if a difference exists in perceived instructional leadership behaviors between administrators and teachers, (d) to determine if a difference exists in perceived instructional leadership behaviors between career and …

Beauty Standards: Negotiations Of Social Life Among African American College Women, Sheena Kaori Gardner

Theses and Dissertations

The literature concerning the relationship between black women and beauty has revealed conflicting findings: some argue that black women are negatively affected by ‘white’ beauty ideals while others argue for the existence of an alternative ‘black’ beauty standard. The purpose of this research is to describe and analyze young African American women’s awareness of beauty standards and their perception of themselves with relation to these standards, examine whether beauty standards are negotiable, and explore how perceptions of self affect daily social interactions. Data were collected through in-depth interviews with black females between the ages of eighteen and twentyive that were …