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Topology And Shape Optimization Of Hydrodynamically–Lubricated Bearings For Enhanced Load-Carrying Capacity, Mohammad Fesanghary

LSU Doctoral Dissertations

Bearings are basic and essential components of nearly all machinery. They must be designed to work under different loads, speeds, and environments. Of all the performance parameters, load-carrying capacity (LCC) is often the most crucial design constraint. The objective of this research is to investigate different design methodologies that significantly improve the LCC of liquid-lubricated bearings. This goal can be achieved by either altering the surface texture or the bearing geometrical configuration. The methodology used here is based on mathematical topological/shape optimization algorithms. These methods can effectively improve the design performance while avoiding time-consuming trial-and-error design techniques. The first category …

Framework Of Damage Detection In Vehicle-Bridge Coupled System And Application To Bridge Scour Monitoring, Xuan Kong

LSU Doctoral Dissertations

Most vibration-based damage identification methods make use of measurements directly from bridge structures with attached sensors. However, the vehicle moving on the bridge can serve as both an active actuator and a response receiver. This dissertation aimed to develop new methodologies to eventually detect bridge damages such as scour using the dynamic response of the vehicle. To reach the final objective, a framework of damage identification was developed first, which gave a guideline on the three crucial steps for damage detection. An optimization method was proposed that combines the Genetic Algorithm (GA) and the First Order (FO) method. It has …

Earth Occultation Imaging Of The Low Energy Gamma-Ray Sky With The Fermi/Gamma-Ray Burst Monitor, James Craig Rodi

LSU Doctoral Dissertations

The hard X-ray/soft gamma-ray sky is highly variable as source intensities can vary on timescales from fractions of a second to years. The type of sources emitting at these energies often include compact objects such as white dwarfs, neutron stars, and black holes interacting with the surrounding environment, which enables the study of the properties and characteristics of these exotic objects. Because the interactions with the environment is often through accretion, most of the emission is in X-rays and gamma-rays Frank et al. 1992 making this energy range critical to understanding the relevant physical processes and mechanisms. Hard X-ray/soft gamma-ray …

Developmental Education Programs : Students' Perceptions Of The Effectiveness At The Community College Level, Thad David Mitchell

LSU Doctoral Dissertations

Developmental education and the surrounding issues of academically underprepared students have been an ongoing source of debate within American higher education. While secondary education systems are frequently blamed for failing to adequately prepare students, community colleges, state colleges, and universities offer developmental programs to aid students in need of remediation in the form of developmental courses. Reading, Math, and English are subjects that are often taught on a developmental level. These courses are designed to provide students with the basic skills needed to be successful in higher education. This research was designed to examine students’ perception of the effectiveness of …

Synthesis Of The Western Hemisphere Of Theonellamide C, Saroj Yadav

LSU Doctoral Dissertations

Theonellamides A-F were isolated from Theonella swinhoei by Fusetani and co-workers. Despite considerable synthetic effort to produce theonellamide F by the Shioiri group in the early 1990’s, the total synthesis of a theonellamide has yet to be reported. We report herein our efforts toward some of the required amino acid residues and construction of the western ring of theonellamide C. We describe the synthesis of an uncoded amino acid, (2S,4R)-ɣ-hydroxy-α-amino adipic acid (Ahad), a building block for theonellamide C. We initially investigated the Corey-Lygo method for the catalytic asymmetric generation of the Cα stereocenter. Unfortunately, the alkylation of glycine benzophenone …

Modeling And Simulation Of Surface Profile Forming Process Of Microlenses And Their Application In Optical Interconnection Devices, Zhengyu Miao

LSU Doctoral Dissertations

Free space micro-optical systems require to integrate microlens array, micromirrors, optical waveguides, beam splitter, etc. on a single substrate. Out-of-plane microlens array fabricated by direct lithography provides pre-alignment during mask fabrication stage and has the advantage of mass manufacturing at low cost. However, this technology requires precise control of the surface profile of microlenses, which is a major technical challenge. The quality control of the surface profile of microlenses limits their applications. In this dissertation, the surface forming process of the out-of-plane microlenses in UV-lithography fabrication was modeled and simulated using a simplified cellular automata model. The microlens array was …

Characterization And Uncertainty Analysis Of Siliciclastic Aquifer-Fault System, Ahmed Saad Elshall

LSU Doctoral Dissertations

The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana, USA, is fluvial in origin. The east-west trending Baton Rouge fault and Denham Springs-Scotlandville fault cut across East Baton Rouge Parish and play an important role in groundwater flow and aquifer salinization. To better understand the salinization underneath Baton Rouge, it is imperative to study the hydrofacies architecture and the groundwater flow field of the Baton Rogue aquifer-fault system. This is done through developing multiple detailed hydrofacies architecture models and multiple groundwater flow models of the aquifer-fault system, representing various uncertain model propositions. The hydrofacies architecture models focus on …

Reciprocal Peer Mentoring : Increasing The Prosocial Behavior Of Socially Neglected Students, Tai A. Collins

LSU Doctoral Dissertations

Two studies investigated the effectiveness of the Reciprocal Peer Mentoring intervention in improving the prosocial behavior of socially neglected elementary school students as measured by a Direct Behavior Rating filled out by their teachers. Reciprocal Peer Mentoring uses the methodological framework of the Check-In/Check-Out intervention (e.g. Hawken & Horner, 2003), but expands on it by using peers as mentors, adding a reciprocity component, focusing on prosocial behavior, and targeting socially neglected students. In Study 1, the effectiveness of Nonreciprocal Peer Mentoring was examined, as popular peers served as mentors for neglected peers. In Study 2, neglected or rejected students mentored …

Synthesis, Characterization And Biological Studies Of Carboranyl-Porphyrin Bioconjugates For Treatment Of Brain Tumors, Naga Venkata Satya Dinesh Kumar Bhupathiraju

LSU Doctoral Dissertations

Chapter 1 gives a brief introduction to brain tumors, approaches to deliver drug across the blood brain barrier (BBB), boron neutron capture therapy (BNCT) for brain tumors, application of carboranyl derivatives in attempt to treat brain tumors using BNCT. Chapter 2 involves synthesis, characterization and toxicity studies (In vitro and In vivo) of high boron containing pegylated cobaltabisdicarbollide porphyrin for treatment of brain tumors using BNCT. To improve the selectivity towards brain tumors we attempted conjugate several peptides to this non-toxic pegylated cobaltabiscabollide porphyrin. In vivo studies were conducted in collaboration with Dr. David G. Baker at LSU veterinary Medicine. …

Contractional Tectonics : The Himalayan Orogen And Perdido Fold-Thrust Belt, Dian He

LSU Doctoral Dissertations

This dissertation focuses on the kinematic evolution of two major categories of contractional tectonics: collisional orogenic belts and toe structures of passive margins, which are characterized by fold-thrust belts that are hundreds of kilometer-scale and tens of kilometer-scale, respectively. The Himalayan orogen is an excellent example of collisional orogenic belts along convergent plate boundaries. It is commonly structurally defined as three stacked units separated by two fault systems: the Main Central thrust (MCT) and South Tibet detachment (STD). The development and emplacement of the middle unit, the Himalayan crystalline core, has long been debated within the extrusion framework, a process …

Ionic Materials For Applications In Sensing And Optoelectronics, Sergio L. De Rooy

LSU Doctoral Dissertations

Organic salts consist of bulky anions and/or cations whose properties can be tailored for specific purposes. Ionic liquids (ILs) are (semi)organic salts with melting points below 100 ºC. They typically exhibit neglible vapor pressures, high thermal stability, wide liquidus range, and tunable solubility. Moreover specific functions can be built into their respective ions. The first part of the dissertation involves discussions of chiral ionic liquids with additional protic, magnetic, and magneto-luminescent properties, respectively. In addition to their enantioselective sensing capabilities, the ILs may find use in chiral separations and catalysis. The second part of the dissertation involves discussions of fluorescent …

Challenges In The Discovery And Characterization Of Magnetic Intermetallics, William A. Phelan

LSU Doctoral Dissertations

The crystal growth and characterization of four families of compounds, LnFeSb3 (Ln = Pr, Nd, Sm, Gd, and Tb) and CeCo(Sb, Sn)3, Ln2Fe4Sb5 (Ln = La – Nd and Sm), LnCu2(Al,Si)5 (Ln = La and Ce), and Ln(Cu,Al,Ga)13 (Ln = La – Pr and Eu), are presented in this dissertation. Special emphasis is placed on describing their structure-magnetic properties correlations. Discoveries and studies of these systems were motivated by their structurally related predecessors, which are comprised of complex structural subunits and exhibit unusual physical properties. The magnetic behaviors exhibited by a selection of these intermetallics include the large magnetoresistances and …

Infrared Laser Ablation For Biological Mass Spectrometry, Fan Huang

LSU Doctoral Dissertations

Instrument and technique development and modeling of ionization methods using infrared (IR) laser desorption and ablation for mass spectrometry (MS) analysis of chemical and biochemical samples are described. Infrared lasers are highly efficient at sample removal and post-ablation ionization of materials removed by IR laser can be used to improve ionization efficiency. Fundamental studies of the physical processes in laser ablation mass spectrometry can help elucidate the mechanism. In this research, an infrared/ultraviolet two-laser matrix-assisted laser desorption ionization (MALDI) MS was developed for analysis of biomolecules. An infrared laser was used to ablate a mixture of analyte and matrix, and …

Investigation Of Electroosmotic Flow Dynamics And Reproducibility In Capillary Electrophoresis, Funda Kizilkaya

LSU Doctoral Dissertations

The goal of this dissertation is to investigate electroosmotic flow (EOF) and electric field dynamics during capillary electrophoresis (CE) experiments using methods based on periodic photobleaching of fluorophores added to the separation buffer at nanomolar concentrations. The methods provide time resolved EOF and local electric field information during an experiment, which can be applied to fundamental studies to provide better understanding of CE techniques. The potential of the EOF monitoring method to improve CE migration reproducibility was investigated in Chapter 2. The EOF monitoring method and four other methods from the literature were applied to the same electrophoretic separations, and …

Red Swamp Crayfish Procambarus Clarkii In The Atchafalaya River Basin: Biotic And Abiotic Effects On Population Dynamics And Physiological Biomarkers Of Hypoxic Stress, Christopher Paul Bonvillain

LSU Doctoral Dissertations

Crayfish harvested from the Atchafalaya River Basin (ARB) represent the majority of Louisiana wild crayfish landings. However, excluding water level influences, it is difficult to elucidate inter-annual harvest differences and intra-annual population variability among habitats. This research investigated ecological influences on population characteristics of red swamp crayfish Procambarus clarkii in the southeastern ARB as well as physiological biomarkers of hypoxic stress in P. clarkii. Biotic and abiotic effects on P. clarkii populations were examined throughout the 2008 and 2009 commercial crayfish seasons. P. clarkii catch per unit effort (CPUE) at sampling locations increased nearly 600% between sample years despite similar …

Dynamic Characterization Of Vocal Fold Virbrations, Zhenyi Wei

LSU Doctoral Dissertations

An emerging trend among voice specialists is the use of quantitative protocols for the diagnosis and treatment of voice disorders. Vocal fold vibrations are directly related to voice quality. This research is devoted to providing an objective means of characterizing these vibrations. Our goal is to develop a dynamic model of vocal fold vibration, and map the parameter space of the model to a class of voice disorders; thus, furthering the assessment and diagnosis of voice disorder in clinical settings.

To this end, this dissertation introduces a new seven-mass biomechanical model for the vibration of vocal folds. The model is …

Synthesis, Cellular Studies, And Computational Analysis Of Porphyrin And Bodipy Conjugates With Affinity For Epidermal Growth Factor Receptor, Alecia Michelle Mccall

LSU Doctoral Dissertations

Chapter 1 is a description of the basic fundamental concepts of porphyrins and BODIPYs, (including synthetic methodologies), a general mechanism of the processes of EGFR, and computational concepts that are elaborated upon in future chapters. Chapter 2 is a discussion solely on the porphyrins that were synthesized to be used as fluorophores for EGFR-targeted conjugates, both peptidic and non-peptidic. The porphyrins were primarily synthesized via the Lindsey method as well as by O-alkylation of tetrahydroxy porphyrins. Synthesis of PEG linkages are discussed as well through three methodologies. Chapter 3 is a presentation of the synthesis, characterization, cellular studies, and computational …

Modeling The Spatial And Temporal Dynamics Of Coastal Marsh Birds, Bradley A. Pickens

LSU Doctoral Dissertations

Wetland birds are likely to be influenced by habitat at multiple spatial scales, yet few studies have investigated bird responses at both broad and fine scales. Northern Gulf Coast marshes are dynamic ecosystems, and they provide an ideal place to examine habitat across spatial and temporal scales. My research focused on the secretive marsh bird guild (i.e. bitterns, rails, gallinules, grebes) with an emphasis on the king rail (Rallus elegans), a species of high conservation concern. My objectives were to investigate the wetland bird-environment relationship across scales, and to model annual changes in bird distribution. Study sites were in the …

The Use Of Discrete Computer Simulation Modeling To Estimate The Direct And Diffusion Effects Of Leadership Development Intervention On The Return On Investment, Brett Wayne Richard

LSU Doctoral Dissertations

Organizational leaders seek monetary returns on their investments (ROI). Thus, making decisions to invest in human capital, such as in leadership development interventions, are often difficult due to the lack of research demonstrating monetary returns on development investment (RODI). Further, little research has been conducted on the diffusion effects of leadership development intervention, or returns on leadership diffusion (ROLD). This research expands on previous research conducted by Avolio, Avey & Quinsenberry (2010), which was the first attempt to estimate RODI using utility analysis. This study is unique in that it uses computer simulation modeling along with current research data to …

Examining The Relationship Between The Exchange Rate, Foreign Direct Investment And Trade, Shanta Parajuli

LSU Doctoral Dissertations

Extensive research has been carried out on the relationships among foreign direct investment (FDI), exports, the exchange rate, and economic growth. However, these research findings are mixed and inconclusive. Therefore, further research and discussion are needed on this topic. This study focused on Mexico, since it is one of the major FDI recipient countries in Latin America and much of its trade is a result of its free trade agreements. This study examines the relationship between FDI, exports, and economic growth in the context of FDI from developed to developing countries (Mexico). The second chapter analyzes the relationship of FDI …

On The Witt Groups Of Schemes, Jeremy Allen Jacobson

LSU Doctoral Dissertations

We consider two questions about the Witt groups of schemes: the first is the question of finite generation of the shifted Witt groups of a smooth variety over a finite field; the second is the Gersten conjecture. Regarding the first, we prove that the shifted Witt groups of curves and surfaces are finite, and that finite generation of the motivic cohomology groups with mod 2 coefficients implies finite generation of the Witt groups. Regarding the second, we prove the Gersten conjecture for the Witt groups in the case of a local ring that is essentially smooth over a discrete valuation …

Resonance And Double Negative Behavior In Metamaterials, Yue Chen

LSU Doctoral Dissertations

In this work, a generic class of metamaterials is introduced and is shown to exhibit frequency dependent double negative effective properties. We develop a rigorous method for calculating the frequency intervals where either double negative or double positive effective properties appear and show how these intervals imply the existence of propagating Bloch waves inside sub-wavelength structures. The branches of the dispersion relation associated with Bloch modes are shown to be explicitly determined by the Dirichlet spectrum of the high dielectric phase and the generalized electrostatic spectra of the complement. For numerical purposes, we consider a metamaterial constructed from a sub-wavelength …

Numerical Study Of Downhole Heat Exchanger Concept In Geothermal Energy Extraction From Saturated And Fractured Reservoirs, Yin Feng

LSU Doctoral Dissertations

Geothermal energy has gained a lot of attention recently due to several favorable aspects such as ubiquitously distributed, renewable, low emission resources while leveraging the advances in the associated technologies such as directional drilling and low enthalpy power generation plant. However, there are still many challenges such as the high initial capital cost of drilling and surface facilities, environmental risk of seismicity due to the induced disequilibrium in the formation, and sustainability of project over designed operational life. Traditional downhole heat exchangers (DHE) could potentially reduce the capital cost and the risk of seismicity, but they are unable to maintain …

Linking Nitrogen Biogeochemistry To Different Stages Of Wetland Soil Development In The Mississippi River Delta, Louisiana, Kelly Marie Henry

LSU Doctoral Dissertations

Extensive wetland loss and nutrient-enhanced eutrophication occur across the Mississippi River delta and include newly emergent landscapes, in the early stages of ecological succession, and older landscape formations, with fully developed ecological communities. Here I tested how the anthropogenic effects of a climate-induced vegetation shift, an oil spill, and nitrate-enrichment regulate the principal environmental factors controlling nutrient biogeochemistry in wetland soils at different stages of development throughout the Mississippi River delta. In the older, transgressing Barataria basin, there was no clear effect of the climate-induced species shift from Spartina alterniflora Loisel to Avicennia germinans L. on soil nutrient chemistry. Observed …

A Numerical Investigation Of Apéry-Like Recursions And Related Picard-Fuchs Equations, Maiia J. Bakhova

LSU Doctoral Dissertations

In this work we investigate a generalization of a recursion which was used by Apery in his proof of irrationality of the zeta function values at 2 and 3. It is a continuation of the work of Zagier , who considered generalization of the first equation and numerically investigated it. The study is made for two generalizations of the second equation, one used the mirror symmetry idea from the theory of Calabi-Yau varieties and another worked with recursion. There were discovered connections between them.

Single-Molecule Detection Of Molecular Beacons Generated From Ldr On Thermoplastic Microfluidic Device For Bioanalysis, Zhiyong Peng

LSU Doctoral Dissertations

Current clinical techniques for nucleic acid detection and analysis often involve PCR, lacking adequate specificity or sensitivity to meet the stringent requirements in certain applications. This research aims to develop an innovative molecular assay and the associated hardware to rapidly signal the presence of certain targets using reporter sequence found in their genome without requiring PCR. This assay coupled the sensitivity of single-pair fluorescence resonance energy transfer (spFRET) with the specificity of ligase detection reaction (LDR) to provide near real-time readout of target biomarkers. Heightened concerns on potential bioterrorism threats, such as rapid dissemination of pathogenic bacteria or viruses into …

Three Essays On Modeling Economic And Fiscal Change For Communities Under Disequilibrium Following Natural Disasters, Arun Adhikari

LSU Doctoral Dissertations

Regional economists and policy makers are interested in forecasting economic changes that are likely to take place at local and state levels after exogenous shocks to an economy; that is, create disequilibrium conditions in terms of supply and demand. Impacts of such shocks could be observed at the level of employment, unemployment, commuting patterns, assessed property values, property and sales taxes and local level of expenditures in several categories. The objective of the first essay was to model the employment change decompositions of different effects in two major industries using a shift share analysis technique in context of Louisiana parishes …

Energy, Environment, And Sustainability: A Hierarchical Analysis Of South Louisiana, Matthew Korbel Moerschbaecher

LSU Doctoral Dissertations

This dissertation details research into the sustainability of industrial, human, and natural systems in south Louisiana. Chapter 1 is a general introduction. Chapter 2 calculates the energy return on financial investment (EROFI) of oil and gas production in the ultra-deepwater Gulf of Mexico (GoM) in 2009 and the Macondo Prospect (Mississippi Canyon Block 252). I calculated a preliminary Energy Return on Investment (EROI) using a range of energy intensity ratios. The EROFI for ultra-deepwater oil and gas at the wellhead was roughly 0.85 gallons, per dollar. These estimates of EROI for 2009 ultra-deepwater oil and natural gas at the wellhead …

The Head And Tail Conjecture For Alternating Knots, Cody Armond

LSU Doctoral Dissertations

The colored Jones polynomial is an invariant of knots and links, which produces a sequence of Laurent polynomials. In this work, we study new power series link invariants, derived from the colored Jones polynomial, called its head and tail. We begin with a brief survey of knot theory and the colored Jones polynomial in particular. In Chapter 3, we use skein theory to prove that for adequate links, the n-th leading coefficient of the N-th colored Jones polynomial stabilizes when viewed as a sequence in N. This property allows us to define the head and tail for adequate links. In …

High-Throughput Sperm Cryopreservation Of Aquatic Species, E Hu

LSU Doctoral Dissertations

The goal of this dissertation was to integrate multiple disciplines for application of high-throughput sperm cryopreservation to aquatic species. The blue catfish Ictalurus furcatus was selected for research due to its role in production of hybrid catfish with eggs from channel catfish Ictalurus punctatus. A high-throughput cryopreservation pathway was developed by systematically evaluating each process factor and using automated processing systems. Large quantities of cryopreserved sperm produced from this protocol were evaluated in commercial-scale hatcheries in cooperation with aquaculture producers. To develop production for commercial requirements, quality characteristics of materials and products were identified and recorded during processing and analyzed …