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Articles 2281 - 2310 of 2324
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Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn
Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn
LSU Doctoral Dissertations
Almost from the very beginning of the digital age, people have sought better ways to communicate with computers. This research investigates how computers might be enabled to understand natural language in a more humanlike way. Based, in part, on cognitive development in infants, we introduce an open computational framework for visual perception and grounded language acquisition called Experience-Based Language Acquisition (EBLA). EBLA can “watch” a series of short videos and acquire a simple language of nouns and verbs corresponding to the objects and object-object relations in those videos. Upon acquiring this protolanguage, EBLA can perform basic scene analysis to generate …
Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev
Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev
LSU Doctoral Dissertations
Advances in computer technologies allow calculations in ever larger model spaces. To keep our understanding growing along with this growth in computational power, we consider a novel approach to the nuclear shell model. The one-dimensional harmonic oscillator in a box is used to introduce the concept of an oblique-basis shell-model theory. By implementing the Lanczos method for diagonalization of large matrices, and the Cholesky algorithm for solving generalized eigenvalue problems, the method is applied to nuclei. The mixed-symmetry basis combines traditional spherical shell-model states with SU(3) collective configurations. We test the validity of this mixed-symmetry scheme on 24Mg and …
Thermal Rheological Analysis Of Cure Process Of Epoxy Prepreg, Liangfeng Sun
Thermal Rheological Analysis Of Cure Process Of Epoxy Prepreg, Liangfeng Sun
LSU Doctoral Dissertations
The cure process of epoxy prepreg used as composite pipe joints was studied by means of differential scanning calorimetry (DSC), Bohlin Rheometer and other techniques. Isothermal DSC measurements were conducted between 110 and 220 oC, at 10 oC intervals. The results show that the complete cure reaction could be achieved at oC. The isothermal cure process was simulated with the four-parameter autocatalytic model. Except in the late stage of cure reaction, the model agrees well with the experimental data, especially at high temperatures. To account for the effect of diffusion on the cure rate, a diffusion factor was introduced into …
Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha
Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha
LSU Doctoral Dissertations
The main objective of this study was to synthesize precursors that are capable of producing copper films of high quality by chemical vapor deposition (CVD). We investigated some copper(I) and copper(II) complexes as precursors for chemical or photochemical vapor deposition. In chapter 2, we synthesized a series of Cu(hfac)2(amine) adducts, where hfac- is hexafluoroacetylacetonate and the amines are: dimethylamine, isopropylamine, allylamine, pyrrolidine, and piperidine. The efficiency of these adducts compared to Cu(hfac)2(H2O) as Cu-CVD precursors was examined under hydrogen. We found that among these amine adducts, Cu(hfac)2(allylamine)2 gave the best …
A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi
A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi
LSU Doctoral Dissertations
A generalized one-dimensional monotone follower control problem with a nonconvex functional is considered. The controls are assumed to be nonnegative progressively measurable processes. The verification theorem for this problem is presented. A specific monotone follower control problem with a nonconvex functional is then considered in which the diffusion term is constant. The optimal control for this problem, which is explicitly given, can be viewed as tracking a standard Wiener process by a non anticipating process starting at 0. For some parameters values, the value function for this monotone follower control problem is shown to be C2 and for other …
Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu
Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu
LSU Doctoral Dissertations
This research develops a comprehensive framework for interactive walkthrough involving one billion particles in an immersive virtual environment to enable interrogative visualization of large atomistic simulation data. As a mixture of scientific and engineering approaches, the framework is based on four key techniques: adaptive data compression based on space-filling curves, octree-based visibility and occlusion culling, predictive caching based on machine learning, and scalable data reduction based on parallel and distributed processing. In terms of parallel rendering, this system combines functional parallelism, data parallelism, and temporal parallelism to improve interactivity. The visualization framework will be applicable not only to material simulation, …
Artificial Peptides Containing Ca,A- Disubstituted Amino Acids: Synthesis, Conformational Studies, And Application As Β-Strand Mimics, Yanwen Fu
LSU Doctoral Dissertations
Short peptides containing Cα,α-dipropylglycine (Dpg) at alternating sequence positions were synthesized and examined for conformational behavior. Peptide assembly was performed using Fmoc-solid-phase chemistry where the coupling with PyAOP could be significantly enhanced at elevated temperature. Circular dichroism (CD) and NMR conformational studies revealed that incorporation of Dpg residues induced folded structures into peptides. It was observed that Dpg residues adopted helical conformation in a helix-promoting sequence. The resulting helical structure was comprised of consecutive β-turns whose structure was stabilized by salt bridge in aqueous solution. In this study, the preparation of sterically and polyfunctional Cα,α-disubstituted amino …
The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo
The Effects Of Local Hydrodynamics On Mass Transfer In Disordered Porous Media, Gang Guo
LSU Doctoral Dissertations
Interfacial mass transfer in disordered media was studied experimentally and numerically. The dissolution of solid benzoic acid spheres in packed columns showed the existence of spatial variations in mass transfer coefficients in monodisperse and polydisperse packings at the same overall Peclet number. The concept of a local Peclet number (single-particle average) was introduced to quantify the effect of local hydrodynamics on local mass transfer. Correlations between Sherwood number and Peclet number having the form Shi=A·(xiPe)m were used to quantify data from various sites in each packing. These experiments also showed that the exponent m varies …
Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown
Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown
LSU Doctoral Dissertations
Pennsylvanian (Desmoinesian) sedimentary rocks within the Paradox Basin Four Corners area of the western United States afford a unique opportunity to study the development of sedimentary successions in a complex marine to nonmarine depositional setting. The close association of thick intervals of nonmarine fan-delta facies adjacent to and in time equivalent position to marine carbonate-evaporite facies suggests complex relationships between the factors affecting deposition. Development of an effective scheme to differentiate the depositional signatures from within these sedimentary successions is the primary goal of this study. To achieve this goal, two objectives were pursued. The first was to calibrate the …
Characterization Of Alligator, Ostrich And Emu Skins And Comparisons To Traditional Leathers, Terri M. Von Hoven
Characterization Of Alligator, Ostrich And Emu Skins And Comparisons To Traditional Leathers, Terri M. Von Hoven
LSU Doctoral Dissertations
Exotic skins and leathers have enjoyed a recent resurgence, as current fashion magazines illustrate. Louisiana would like to increase its niche in the exotic skins market by increasing alligator, ostrich and emu skin usage, mainly by inspiring designers to incorporate them into their repertoire. The possibilities are endless from apparel and trim to upholstery and other home furnishings to accessories; Louisiana exotic skins have significant market potential. In order to assist in these traditional textile applications, characterization of the various skin properties needs to be completed. The research was carried out in three stages. For the preliminary research, one emu …
Log-Derived Cation Exchange Capacity Of Shaly Sands : Application To Hydrocarbon Detection And Drilling Optimization, Gamze Ipek
LSU Doctoral Dissertations
Researchers at Louisiana State University, LSU, have introduced several petrophysical models expressing the electric properties of shaly sands. These models, to be used for hydrocarbon detection, are based on the Waxman and Smits concept of supplementing the water conductivity with a clay counterions conductivity. The LSU models also utilize the Dual Water theory, which relates each conductivity term to a particular type of water, free and bound, each occupying a specific volume of the total pore space. The main difference between these models and the other shaly sand models is that the counterion conductivity is represented by a hypothetical sodium …
Relationship Between Neuropsychological Deficits And Cerebral Perfusion Abnormalities In Cocaine Abusers, Karen A. Tucker
Relationship Between Neuropsychological Deficits And Cerebral Perfusion Abnormalities In Cocaine Abusers, Karen A. Tucker
LSU Doctoral Dissertations
The purpose of this study was to investigate the relationships between the severity of cocaine/alcohol use, neuropsychological functioning, and cerebral blood flow abnormalities. Cocaine users (n = 60) and control subjects (n = 13) were administered a battery of neuropsychological tests that yielded the following factors: Attention/Executive Functioning, Memory, Simple Motor, and Sensorimotor. Participants were assessed for decreased cerebral blood flow with single-photon emission computed tomography (SPECT). Examination of group differences indicated that cocaine users performed significantly worse than controls on the Memory and Sensorimotor factors. The frequency/duration of cocaine use, alcohol use, and a combination of both substances were …
Retention And Movement Of Reactive Chemicals In Soils, Hongxia Zhu
Retention And Movement Of Reactive Chemicals In Soils, Hongxia Zhu
LSU Doctoral Dissertations
Adsorption-desorption and transport behavior of pesticides are important processes that influence the amount retained by the soil and that which is susceptible to runoff or movement within the soil profile. Kinetic batch experiments were used to study the adsorption-desorption behavior of metolachlor (a non-ionic herbicide) and deltamethrin (a pyrethroid insectcide) in soils, and atrazine (a triazine) in sugarcane mulch residue. Miscible displacement experiments under steady flow conditions were carried out to examine the mobility of these pesticides in soils. Metolachlor adsorption and desorption by Sharkey clay soil(Very-fine, smectitic, thermic Chromic Epiaquerts) and Commerce silty loam soil (Fine-silty, mixed, superactive, nonacid, …
Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee
Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee
LSU Doctoral Dissertations
Successful algorithmic music composition requires the efficient creation of works that reflect human preferences. In examining this key issue, we make two main contributions in this dissertation: analysis of the computational complexity of algorithmic music composition, and methods to produce music that approximates a commendable human effort. We use species counterpoint as our compositional model, wherein a set of stylistic and grammatical rules governs the search for suitable countermelodies to match a given melody. Our analysis of the complexity of rule-based music composition considers four different types of computational problems: decision, enumeration, number, and optimization. For restricted versions of the …
Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty
Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty
LSU Doctoral Dissertations
I examined patterns and timing of ontogeny and relative growth in five species of blenny (Teleostei: Blenniidae) from the northern Gulf of Mexico by assigning a suite of discrete character state scores to ontogenetic events (10 external traits; 218 total specimens). This is the first study to evaluate developmental patterns in reef-associated fishes relative to the timing of metamorphosis and settlement by applying scaling techniques and statistical methods to quantify, differentiate, and select criteria for defining intervals of development across taxa. Blennies settle at a common state of ontogeny and share a common pattern of body and fin/cirrus growth. Three …
Numerical Study Of Water Coning Control With Downhole Water Sink (Dws) Completions In Vertical And Horizontal Wells, Solomon Ovueferaye Inikori
Numerical Study Of Water Coning Control With Downhole Water Sink (Dws) Completions In Vertical And Horizontal Wells, Solomon Ovueferaye Inikori
LSU Doctoral Dissertations
Approximately 2.5 billion dollars is spent annually to solve the problem of produced water in oil and gas wells. Downhole Water Sink (DWS) technology is one industry solution to control water coning in oil wells. DWS technology involves the segregated production of oil and water through separate completions with zonal isolation packer. However, several problems have been experienced in the application of the technology in watered-out oil wells. This study identified two factors that could aid in a better modeling of the technology in old vertical wells – inclusion of capillary transition pressures and relative permeability hysteresis. It also identified …
Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu
Numerical Studies Of Reactive Polymer Flows In Porous Materials, Honggao Liu
LSU Doctoral Dissertations
This dissertation presents a new numerical model of reactive polymer flow in heterogeneous porous media. A moment representation of the log-normal polymer molecular weight distribution is used to model polymer as a multi-component species. Three leading moments are used to simulate the polymer transport and reaction processes in a two-dimensional porous medium. A new operator splitting technique that allows the moment equations for polymerization to be incorporated into a finite-difference transport model is developed. The novelty of this approach is the use of two different dependent variables (for the transport versus reaction parts of the problem). It is significant from …
The Effects Of Songs In The Foreign Language Classroom On Text Recall And Involuntary Mental Rehearsal, Claudia Smith Salcedo
The Effects Of Songs In The Foreign Language Classroom On Text Recall And Involuntary Mental Rehearsal, Claudia Smith Salcedo
LSU Doctoral Dissertations
This study investigated the effect of music on text recall and involuntary mental rehearsal (din) with students from four college-level Beginning Spanish classes. Two groups heard texts as songs, one group heard the same texts as speech, and one group was the control group. For the text recall variable, a cloze test was administered at the end of each song treatment to determine total words recalled. Students from one of the music groups heard the melody of the song while testing. For the din variable, students were asked to report on the amount of this phenomenon experienced. Data was collected …
Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang
Mechanism Of The Nicofe Ternary Alloy Deposition, Yun Zhuang
LSU Doctoral Dissertations
Electrodeposited NiCoFe ternary alloys are of interest for their magnetic and thermophysical properties. The reaction rates and resulting composition and current efficiency are often determined empirically, due to a lack of understanding of the electrodeposition mechanism and coupled mass transport. Therefore, the effects of electrolyte concentration, bulk pH and solution agitation are studied over a wide range of applied current densities to investigate the interrelated behavior of the partial reaction rates. The Fe rate during alloy deposition is independent of Co2+ and Fe2+ bulk concentrations, but is enhanced compared with its single metal rate. Both catalytic and inhibiting effects are …
Analytical Model To Control Off - Bottom Blowouts Utilizing The Concept Of Simultaneous Dynamic Seal And Bullheading, Victor Gerardo Vallejo-Arrieta
Analytical Model To Control Off - Bottom Blowouts Utilizing The Concept Of Simultaneous Dynamic Seal And Bullheading, Victor Gerardo Vallejo-Arrieta
LSU Doctoral Dissertations
The current methods for off - bottom control of blowouts involve pumping kill fluid into the well through an injection string. These are the dynamic kill and the momentum kill. The dynamic kill, which is based on the steady state system analysis approach, and the momentum kill, that is loosely based on the Newton's Second Law of Motion, have been used extensively in off-bottom control of actual blowouts. A comprehensive study of these two concepts was performed. The review included an analytical analysis of the published design techniques for both of these methods. The application of these techniques to several …
Analysis Of Diagnostic Testing Of Sustained Casing Pressure In Wells, Rong Xu
Analysis Of Diagnostic Testing Of Sustained Casing Pressure In Wells, Rong Xu
LSU Doctoral Dissertations
Over 8,000 wells in the Gulf of Mexico exhibit sustained casing pressure (SCP). SCP is defined as “any measurable casing pressure that rebuilds after being bled down, attributable to cause(s) other than artificially applied pressures or temperature fluctuations in the well”. The Minerals Management Service (MMS) regulations consider SCP hazardous and, in principle, require its elimination. In some cases the agency may allow continuing production at a well with SCP by granting a temporary “departure” permit. The departure permits are based on diagnostic tests involving pressure bleed-down through a 0.5-inch needle valve followed by closing the valve and recording pressure …
Synthesis And Properties Of Novel Macrocycles And Related Chromophoric Benzenoid Compounds, Jorge O. Escobedo Cordova
Synthesis And Properties Of Novel Macrocycles And Related Chromophoric Benzenoid Compounds, Jorge O. Escobedo Cordova
LSU Doctoral Dissertations
The synthesis and properties of some macrocyclic compounds of interest are presented. Resorcinarenes with functionalized conjugated rigid rods made of oligo-p-phenylenes would lead to an entirely new class of functional, soluble, well-defined architectures impacting a variety of multidisciplinary research efforts. The general synthetic design described in this document could be readly extrapolated to include other electronic systems such as heteroaromatics and polyenes. An extensive collaborative study of chromophore formation in resorcinarene solutions is also described here. The study reveals that upon oxidation, the reversible conversion to acyclic precursors occur first, and then these precursors undergo oxidation to quinoid-type compounds (xanthenes). …
Essays On The Bayesian Inequality Restricted Estimation, Asli K. Ogunc
Essays On The Bayesian Inequality Restricted Estimation, Asli K. Ogunc
LSU Doctoral Dissertations
Bayesian estimation has gained ground after Markov Chain Monte Carlo process made it possible to sample from exact posterior distributions. This research aims at contributing to the ongoing debate about the relative virtues of the Frequentist and Bayesian theories by concentrating on the qualitative dependent variable models. Two Markov Chain Monte Carlo (MCMC) methods have been used throughout this dissertation to facilitate Bayesian estimation, namely Gibbs (1984) sampling and the Metropolis (1953, 1970) Algorithm. In this research, several Monte Carlo experiments have been carried out to better understand the finite sample properties of Bayesian estimator and its relative performance to …
Essays On International Trade And Bayesian Forecasting, Dennis S. Edwards
Essays On International Trade And Bayesian Forecasting, Dennis S. Edwards
LSU Doctoral Dissertations
Economic theory is subject to continual analysis. While theories themselves are sometimes widely accepted, nuances of theory are persistently scrutinized. Researchers have not isolated this debate from a simply theoretic standpoint. Empirical methods in microeconomics also provide a forum for disagreement. This dissertation studies two topics of microeconomic theory that are constantly in debate: integration and cost function estimation. From the standpoint of theoretical integration models in international trade theory, the concept of foreign direct investment is studied in both a horizontal and vertical setting. With respect to horizontal integration, this dissertation modifies the Brander-Krugman reciprocal dumping model to evaluate …
Branch, Crown, Tree And Stand Water Flux In An 180-Year-Old Loblolly Pine Plantation After Thinning, Fertilization, And Throughfall Exclusion Treatments, Shufang Yu
LSU Doctoral Dissertations
Branch and tree sap flux density (SFD) was measured to evaluate the effects of thinning, fertilization, and throughfall exclusion treatments on water use by loblolly pine (Pinus taeda L.) trees. Variations in SFD at different radial xylem depths were also examined to improve estimates of tree water use from sap flux density measured in the outer sapwood. This study was conducted in an 18-year-old loblolly pine plantation in central Louisiana in 1999. The results revealed that SFD was higher in the outer xylem than in the inner xylem and large trees had higher SFD than small trees. Thinning increased daily …
Explicit Multiplicative Relations Between Gauss Sums, Brian J. Murray
Explicit Multiplicative Relations Between Gauss Sums, Brian J. Murray
LSU Doctoral Dissertations
H.Hasse conjectured that all multiplicative relations between Gauss sums essentially follow from the Davenport-Hasse product formula and the norm relation for Gauss sums. While this is known to be false, very few counterexamples, now known as sign ambiguities, have been given. Here, we provide an explicit product formula giving an infinite class of new sign ambiguities and resolve the ambiguous sign in terms of the order of the ideal class of quadratic primes.
Modeling Canopy Structure Effects On Loblolly Pine Growth, Mauricio Jerez Rico
Modeling Canopy Structure Effects On Loblolly Pine Growth, Mauricio Jerez Rico
LSU Doctoral Dissertations
This study examined several aspects of canopy structure and their influence on growth of loblolly pine (Pinus taeda L.) plantations. Foliage distribution, crown hydraulic architecture, and the effect of chronological changes in canopy structure on stand development were explored as possible components of a future process-based model intended for management purposes. A model based on the Johnson’s SB distribution was developed to predict leaf area distribution of loblolly pine trees. This is a preliminary step for building a submodel capable of simulating chronological changes in canopy structure and stand growth. The model accurately predicted the cumulative distribution of leaf area …
Peroxynitrite-Mediated Oxidations: Nitration And Nitrosation, Rachel Bolzan
Peroxynitrite-Mediated Oxidations: Nitration And Nitrosation, Rachel Bolzan
LSU Doctoral Dissertations
Using a direct ultraviolet second-derivative spectroscopy method, three peroxynitrite preparative methods were investigated for the nitrite and nitrate present either as impurities or produced during peroxynitrite decomposition: (I) ozonation of azide, reaction of hydrogen peroxide with (II) isoamyl nitrite and (III) nitrous acid. The oxidation of morpholine by peroxynitrite in the presence and absence of added carbonate gives N-nitromorpholine and N-nitrosomorpholine. Nitration and nitrosation of morpholine are catalyzed by low levels of CO2; however, excess CO2 dramatically reduces the yields of nitrosation but not nitration, and the combined yields of the products are about the same under …
A Factorization Approach For Solving The Hamilton-Jacobi Equations In Nonlinear Optimal Control, Mohammad Dikko Aliyu
A Factorization Approach For Solving The Hamilton-Jacobi Equations In Nonlinear Optimal Control, Mohammad Dikko Aliyu
LSU Doctoral Dissertations
The Hamilton-Jacobi equation (HJE) arose early in the last century in the study of the calculus of variation, classical mechanics and Hamiltonian systems. Recently, there has been a renewed interest in HJEs arising in various analysis and synthesis problems in systems theory. The HJE despite providing a necessary and sufficient condition for an optimal control, is very difficult to solve for general nonlinear systems, and therefore its application remained limited to linear systems. Yet, the HJE has been studied extensively in the literature from diverse areas of science and engineering, varying from mathematical physics, to mechanics, control theory, and to …
Northern Pintail Nest Site Selection, Nest Success, Renesting Ecology And Survival In The Intensively Farmed Prairies Of Southern Saskatchewan: An Evaluation Of The Ecological Trap Hypothesis, Kenneth Daniel Richkus
Northern Pintail Nest Site Selection, Nest Success, Renesting Ecology And Survival In The Intensively Farmed Prairies Of Southern Saskatchewan: An Evaluation Of The Ecological Trap Hypothesis, Kenneth Daniel Richkus
LSU Doctoral Dissertations
Unlike most prairie nesting ducks (Anas spp.), the North American population of northern pintails (A. acuta, hereafter pintails) has failed to respond as expected to improved wetland conditions on the U.S. and Canadian prairies during the mid to late 1990s. My primary objectives were to test the “ecological trap hypothesis” on a landscape level by examining pintail nest site selection and nest success in a highly agricultural environment in southern Saskatchewan. I also used radiotelemetry to estimate renesting and breeding season survival rates of female pintails; two parameters that are important in productivity and life cycle models. Most (51%) pintail …