Digital Commons Network^™

Adjoint-Based Error Estimation And Grid Adaptation For Functional Outputs From Cfd Simulations, Ravishankar Balasubramanian

Theses and Dissertations

This study seeks to reduce the degree of uncertainty that often arises in computational fluid dynamics simulations about the computed accuracy of functional outputs. An error estimation methodology based on discrete adjoint sensitivity analysis is developed to provide a quantitative measure of the error in computed outputs. The developed procedure relates the local residual errors to the global error in output function via adjoint variables as weight functions. The three major steps in the error estimation methodology are: (1) development of adjoint sensitivity analysis capabilities; (2) development of an efficient error estimation procedure; (3) implementation of an output-based grid adaptive …

Finite Element Simulations Of Three-Dimensional Microstructurally Small Fatigue Crack Growth In 7075 Aluminum Alloy Using Crystal Plasticity Theory, Stephen R (Stephen Riley) Johnston

Theses and Dissertations

This thesis discusses plasticity-induced crack closure based finite element simulations of small fatigue cracks in three dimensions utilizing crystal plasticity theory. Previously, modeling has been performed in two dimensions using a double-slip crystal plasticity material model. The goal of this work is to extend that research using a full three-dimensional FCC crystal plasticity material model implementation that accounts for all twelve FCC slip systems. Discussions of Python scripts that were written to perform analyses with the commercial finite element code ABAQUS are given. A detailed description of the modeling methodology is presented along with results for single crystals and bicrystals. …

The Development Of A Methodology For Assessing Industrial Workstations Using Computer-Aided Ergonomics And Digital Human Models, Jinyan Du

Theses and Dissertations

This study examined an existing industrial workstation at an automobile assembly plant using computer aided ergonomics and digital human models. The purpose of this evaluation was the development of a methodology useful for evaluating workstations to identify potential design issues that could result in musculoskeletal injury in a real work environment. An ergonomic risk assessment was conducted on a lifting task while being performed both manually and using an assist device. JACK digital human modeling and ergonomics software were used to conduct a computer-based ergonomic analysis. Four analysis tools in JACK (static strength analysis, rapid upper limb assessment, metabolic energy …

Evaluation Of Chitosan Gelatin Complex Scaffolds For Articular Cartilage Tissue Engineering, Harshal Prabhakar Mahajan

Theses and Dissertations

In search of better scaffolding materials for in vitro culture of chondrocytes, the combination of chitosan (similar to glycosoaminoglycans) and gelatin (denatured collagen) was tested due to its resemblance to cartilage extra-cellular matrix (ECM). Porous scaffolds were fabricated from chitosan gelatin blends (1:1, 2:1, and 3:1). The response of chondrocytes to them was evaluated from the amount of sulphated GAG and collagen type 2 secreted after 3 and 5 weeks. The effect due to static (transwell inserts) and dynamic (rotating bioreactor) culture methods was analyzed. Results indicate that 1:1 chitosan gelatin blends showed the best chondro-conductive potential. The rotating bioreactor …

3d Wavelet-Based Algorithms For The Compression Of Geoscience Data, Justin Thomas Rucker

Theses and Dissertations

Geoscience applications generate large datasets; thus, compression is necessary to facilitate the storage and transmission of geoscience data. One focus is on the coding of hyperspectral imagery and the prominent JPEG2000 standard. Certain aspects of the encoder, such as rate-allocation between bands and spectral decorrelation, are not covered by the JPEG2000 standard. This thesis investigates the performance of several JPEG2000 encoding strategies. Additionally, a relatively low-complexity 3D embedded wavelet-based coder, 3D-tarp, is proposed for the compression of geoscience data. 3D-tarp employs an explicit estimate of the probability of coefficient significance to drive a nonadaptive arithmetic coder, resulting in a simple …

An Adaptive Wireless Lan Mac Scheme To Achieve Maximum Throughput And Service Differentiation, Wei Zha

Theses and Dissertations

With the explosive deployment of wireless LAN technology in the past few years and increasing demand on multimedia applications, the efficient utilization of the precious wireless radio link resources and support of Quality of Service (QoS) in WLANs has become a prominent research issue. In this thesis, an adaptive p-persistent based I 802.11 MAC scheme in WLANs has been proposed. The proposed scheme can maximize the total channel throughput, and also provide service differentiation among multiple traffic classes. This is achieved by updating the transmission probabilities for the stations that compete for transmissions in a WLAN, adaptively based on the …

The Use Of Compression Precracking Constant Amplitude (Cpca) Test Method To Obtain Near-Threshold Fatigue Crack Growth Behavior In Aa7075-T7351, Dustin Henry Mcknight

Theses and Dissertations

Traditionally, pre-cracking has been performed under tension-tension loading, followed by a load reduction scheme to obtain fatigue crack growth rate data in the near threshold regime. These data have been shown to exhibit load history effects due to remote crack closure. An alternative test method has been developed to minimize these load history effects. This test procedure uses compression pre-cracking to initiate a crack, followed by constant amplitude loading to grow the crack to failure. Compression-compression (C-C) loading as a means of forming a starter crack for fatigue crack growth is a relatively new concept. Cracks grown under C-C loading …

Fast Reconfiguration Algorithm Development For Shipboard Power Systems, Yan Huang

Theses and Dissertations

Todays protection schemes for shipboard applications, such as the zone-based differential protection, are efficient, fast, and reliable for fault detection. However, these protection schemes do not consider the system stability or power balance problems that occur with fault isolation and the system reconfiguration. This thesis focuses on developing the extended protection function including the fast reconfiguration function that intends to maintain the power balance of the unfaulted subsystem. Graph theory is utilized to represent the shipboard power system topology in matrices, and matrix operations are developed to represent the corresponding power system topology change and evaluate the outcome of the …

Fatigue Crack Growth Under Residual Stresses Around Holes, Ramesh Nagaralu

Theses and Dissertations

Compressive residual stresses induced by tensile overloads, compressive under loads, or by a cold-expansion process in specimens containing a circular hole and their influence on subsequent fatigue crack growth in aluminum alloys are studied. The finite element method is used to calculate residual stresses. The superposition method, which uses crack-tip stress intensity factors for cases involving remote loading and residual stresses, is used to calculate crack growth life for three kinds of tests from the literature: (1) fatigue of a circular hole specimen after an overload or under load, (2) single crack growing from a circular hole after a severe …

Work Replication: A Communication Optimization For Loci, Krunal Navinchandra Soni

Theses and Dissertations

For distributed memory architectures, communication cost is a significant source of overhead in parallel scientific applications. Many proposed communication optimizations duplicate the behavior of well-written hand-tuned parallel code. Because of continuous changes in architectural components, these types of low-level optimizations are not always effective. This thesis seeks to develop a high-level optimization of work replication in which computations are replicated to minimize communications. There exist performance trade-offs between computation cost and communication cost because of work replication. Due to these trade-offs, it is required to determine which computations should be replicated to improve overall performance. This research presents the development …

Three Students Mourned, Staff Report

University of Mississippi News

OXFORD, Miss. - The University of Mississippi mourns the loss of three students who died in a one-car accident south of Batesville early Saturday morning.

Plasma Steroid And Vitellogenin Concentrations, Activity Of Cathepsins, And Egg Protein Content During Oocyte Maturation, And Influence Of Hormone Injection In Four Commercial Strains Of Channel Catfish Ictalurus Punctatus, Marinela Barrero-Monzon

Theses and Dissertations

Profiles of plasma estradiol and testosterone concentrations, cathepsin D, L, and B activities, and quantitative and qualitative protein content were developed and evaluated in four commercial strains of channel catfish, Gold Kist (2), Thompson and NWAC-103 for one year (age 2 to age 3). Great variation between individuals of the same strain precluded the identification of any significant, strain-specific differences for the variables under investigation. When variables from fish of all strains were collectively evaluated over time, both estradiol and testosterone concentrations significantly increased in July and then later from February to April. The increase in hormone concentration was accompanied …

Levanna Wilson Lester

African American Funeral Programs

Interment at Scarboro Grove Baptist Church Cemetery in Portal, Georgia

Study Of Partial Discharge Activity In Magnet Wires Aged By Combined Stresses, Ashwini Mani

Theses and Dissertations

Partial discharge testing is a nondestructive method of identifying possible premature insulation breakdown. Magnet wires are used in various electrical equipment like injection coils, solenoids, small transformers and motors. Winding wires used in high voltage systems are subjected to several stresses during operation, which considerably lowers their lifetime. A prolonged combined effect of these stresses causes aging of the wires, inception of partial discharge activity, and degradation of the organic material in the enamel coating and varnish used by the manufacturer. The tests were conducted for AWG 30 and AWG 31 twisted magnet wire samples. The samples are aged under …

A Consideration Of Church Planting Through Radio Broadcasting In Thailand, Byung Jo Chang

Doctoral Dissertations and Projects

This dissertation focuses on the meaning of church planting, and the successful church planning through radio broadcasting and its benefit in Thai missions. Radio broadcasting is the best way of opening up the door for spreading the gospel to start church planting. The research focuses on founding and organizing the broadcasting station in the hopes of giving non Christians opportunities to hear the gospel for the first time, and helping them to become Chris like.

The potential radio broadcasting missions carry, the meaning of it all, and the efficiency behind planting a church through the broadcasting missions is examined. These …

Empirical Findings On Persuasiveness Of Recommender Systems For Customer Decision Support In Electronic Commerce, Qinyu Liao

Theses and Dissertations

More and more companies are making online presence by opening online stores and providing customers with company and products information but the overwhelming amount of information also creates information overload for the customers. Customers feel frustrated when given too many choices while companies face the problem of turning browsers into actual buyers. Online recommender systems have been adopted to facilitate customer product search and provide personalized recommendation in the market place. The study will compare the persuasiveness of different online recommender systems and the factors influencing customer preferences. Review of the literature does show that online recommender systems provide customers …

Screening Soybean Genotypes For High Temperature Tolerance By In Vitro Pollen Germination, Pollen Tube Length And Physiological Techniques, Mohammed A. Salem

Theses and Dissertations

We are now witnessing changing environmental conditions and these changes will likely continue into the coming decades due to projected increases in temperatures on the earth surface. Recent model projections suggest that the global mean surface air temperatures will increase by 1.4 to 5.8 °C by 2100. The consequences of these high temperatures include reductions in crop yields. Soybean is one of the major crops grown in the US, where high temperatures (>35 °C) during reproductive growth decreased yield. Two experiments were conducted to determine the effects of temperature on soybean pollen germination properties and identify responses to temperature …

Madrigal Dinners: 50th Anniversary Season, December 10, 2005, School Of Music

School of Music Programs

Bone Student Center
December 10, 2005
3:00 p.m.

Biomechanical And Metabolic Changes Within Rabbit Articular Cartilage Following Treatment With Radiofrequency Energy, Christopher Larry Horstman

Theses and Dissertations

The effects caused to articular cartilage by the remote use of arthroscopically-delivered RF energy to soft tissues in the joint are unknown. This investigation reported the short and long-term effects of bRF and mRF energy on the biomechanical properties and metabolic activity of articular cartilage. In addition, the effect of Cosequin® therapy was addressed. Thirty New Zealand white rabbits were randomly assigned to one of two treatment groups (Group 1 - placebo; Group 2 - Cosequin®). Histopathology, cell viability, GAG synthesis, and mechanical function of the articular cartilage were compared between groups. Data were analyzed using a mixed model ANOVA …

Online Professional Development: The Experiences Of A First-Time Facilitator, Renee Gammill

Theses and Dissertations

Donmoyer (1990) suggested that knowledge gained from our own experiences or that of others may be applied to the improvement of practice. The purpose of this study was to provide insight into the experiences of a first-time online facilitator. The research question for this study was: How does a first-time facilitator understand the process of delivering instruction in an online environment? A case study design was applied to this research. The researcher/participant was the case under study in the context of the delivery of online instruction. The researcher who was also the online instructional facilitator experienced the process of delivering …

Individualistic Roamers Or Community Builders?:Differences And Boundaries Among Rvers, Gloria Anne Mattingly

Theses and Dissertations

The number of leisure and working RVers roaming America?s highways, now conservatively estimated at over eight million, continues to increase (Curtin 2001; Sommer 2003). In spite of their growing presence and unique lifestyle, these populations remain sociologically understudied. This exploratory case study of two distinctly different RV parks is a small but significant step toward filling that research gap. At both RV parks I found a diverse population of individualists who value self-contained travel, freedom, relaxation, and sociality. In spite of sharing a collective, subcultural lifestyle, they differed along multiple axes. Marked differences separate RVers into three broad groups (full-timers, …

Evaluation Of Hatchery And Growout Factors For The Successful Production And Stocking Of Juvenile Gulf Coast Walleye, Justin L. Wilkens

Theses and Dissertations

Temperature-dependent weight gain of Gulf coast and northern strain walleye Sander vitreus fingerlings was determined by rearing fish in flow-through aquaria at different water temperatures (range 15-32°C). Maximum growth of Gulf coast and northern strain walleye occurred between 20 and 26°C, and weight gain of northern walleye exceeded that of the Gulf coast strain by 1.5 times. An acclimated chronic exposure method to assess upper thermal limits determined that walleye survived 35, 9, and 1 days at 33, 34, and 35°C, respectively. A post pond-rearing feed-training practice (21 d) at a mean density of 6,290 ± 1,247 fish/m3 using formulated …

Critical Analysis Of Sic Sit Design And Performance Based Upon Material And Device Properties, Yunmo Sung

Theses and Dissertations

Recently, the need for high power, high frequency devices continues to grow with the increase in wireless communication, radar systems, HDTV, digital communication, and other military application of the RF spectrum. Traditionally when higher power is needed, one needs to either combine the output power of multiple devices or use vacuum tubes, which are still uncontested at very high power levels, capable of up to a few hundred kilowatts at 5 GHz [11]. But wide band gap semiconductor devices capable of competing in this application. Moreover, the static induction transistor (SIT) in silicon carbide can provide very high total power …

Cyanate Ester, Epoxy And Epoxy/Cyanate Ester Matrix Polyhedral Oligomeric Silsesquioxane Nanocomposites, Kaiwen Liang

Theses and Dissertations

Cyanate ester (PT-15, Lonza Corp) composites containing the inorganic-organic hybrid polyhedral oligomeric silsesquioxanes (POSS), octaaminophenyl(T8)POSS (C6H4NH2)8(SiO1.5)8, cyanopropylheptacyclopentyl(T8)POSS, (C5H9)7(SiO1.5)8(CH2) 3CN or TriSilanolPhenylPOSS (C42H38O12Si7), were synthesized respectively. These PT-15/POSS composites were characterized by FT-IR, X-ray diffraction (XRD), small-angle neutron scattering (SANS), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and three-point bending flexural tests. XRD, TEM and IR data are all consistent with molecular dispersion of octaaminophenyl(T8)POSS and TriSilanolPhenylPOSS due to the chemical bonding of the POSS macromer into the continuous cyanate ester network phase. In contrast to octaaminophenyl(T8) POSS and TriSilanolPhenylPOSS, …

An Investigation Of Firms' Earnings Management Practices Around Product Recalls, Zeeshan Ahmed

Theses and Dissertations

This study investigates the earnings management practices of firms around product recalls. In recent years, the management of earnings around firm-specific events has received considerable attention in the finance and accounting literature. New equity issues, mergers and acquisitions, share repurchases, and management buyouts are some events around which at least some firms have been shown to manage their earnings to achieve managements? objectives. Product recalls offer yet another interesting occasion when managers have incentives to cover up the true financial performance of their firms and mislead investors. In order to determine whether firms announcing product recalls manage earnings more aggressively …

An Investigation Of The Performance In College Algebra Of Students Who Passed The Summer Developmental Program At Mississippi State University, Martha Hall Pratt

Theses and Dissertations

At Mississippi State University (MSU), students who do not meet full admission requirements may enroll in the Summer Developmental Program (SDP). During this ten-week summer program, students take four developmental courses to prepare them for college-level courses. MA 0003 Developmental Mathematics is the course designed to prepare these students for MA 1313 College Algebra. In addition, the Department of Mathematics and Statistics at MSU offers MA 0103 Intermediate Algebra to prepare students for MA 1313 College Algebra. The purpose of this study was to determine (a) whether there were correlations between student grades in MA 0003, MA 0103, and MA …

Approximate Methods For Solving Flowshop Problems, Pramod Jain

Theses and Dissertations

The flow shop scheduling problem is a classical combinatorial problem being studied for years. The focus of this research is to study two variants of the flow shop scheduling problem in order to minimize makespan by scheduling n jobs on m machines. A solution approach is developed for the modified flow shop problem with due dates and release times. This algorithm is an attempt to contribute to the limited literature for the problem. Another tabu search-based solution approach is developed to solve the classical flow shop scheduling problem. This meta-heuristic (called 3XTS) allows an efficient search of the neighboring solutions …

Mechanical And Physical Properties Of Preservative-Treated Strandboard, John Warren Kirkpatrick

Theses and Dissertations

The purpose of this research was to quantify properties of strandboard panels manufactured with various preservatives at loading levels effective against native termites. Panels were manufactured using nine different formulations. The method of preservative addition was also examined for some preservative formulations, increasing the total number of preservative treatments to twelve. Panels were manufactured with one target retention for each preservative treatment. An effective preservative loading relative to termites was established by previous studies or referencing current standards. Mechanical testing performed included static bending and internal bond. Physical testing included water absorption, thickness swell, and linear expansion. Few treatments met …

Investigating Traditional Instruction And Problem-Based Learning At The Elementary Level, Ann Wiley Scott

Theses and Dissertations

The purpose of this study was to determine if Problem-Based Learning (PBL) is as effective an instructional method at the elementary level as traditional instruction in learning content. This study also is a contribution to the literature on PBL in the elementary classroom. The research design was quasi-experimental with a non-equivalent control group. A pilot study was conducted in science classes prior to the commencement of the research project in social studies. Eighty-eight students participated in the two studies. The control groups received instruction in a traditional format, and the experimental groups received instruction through the use of PBL. The …

Testing The Floristic Quality Assessment Index In Natural And Created Wetlands In Mississippi, Usa, Brook Danielle Herman

Theses and Dissertations

The U.S. Environmental Protection Agency has mandated that states must include the use of biological assessments in their water quality laws to assess the biological integrity of aquatic systems. The Floristic Quality Assessment Index (FQAI), which uses wetland vegetation to assess the biological integrity of an ecosystem, has not been tested in Mississippi. The purpose of this study was to test the efficiency of the FQAI in wetlands along a gradient of human influence. Coefficients of conservatism (CC) were assigned to plant species based on their tolerance to disturbance and fidelity to habitat. A negative correlation was found between the …