51 |
Preconditioned solenoidal basis method for incompressible fluid flowsWang, Xue 12 April 2006 (has links)
This thesis presents a preconditioned solenoidal basis method to solve the algebraic
system arising from the linearization and discretization of primitive variable
formulations of Navier-Stokes equations for incompressible fluid flows. The system
is restricted to a discrete divergence-free space which is constructed from the incompressibility
constraint. This research work extends an earlier work on the solenoidal
basis method for two-dimensional flows and three-dimensional flows that involved the
construction of the solenoidal basis P using circulating flows or vortices on a uniform
mesh. A localized algebraic scheme for constructing P is detailed using mixed finite
elements on an unstructured mesh. A preconditioner which is motivated by the analysis
of the reduced system is also presented. Benchmark simulations are conducted
to analyze the performance of the proposed approach.
|
52 |
Effects of instruction in creative problem solving on cognition, creativity, and satisfaction among ninth grade students in an introduction to world agricultural science and technology courseAlexander, Kim Darwin 17 September 2007 (has links)
The use of Creative Problem Solving (CPS) as an instructional strategy to increase the creativity levels of students across all levels of the curriculum is currently a popular topic of investigation. Curriculum content and the underlying objectives that are presented to students in public schools have been the subject of close scrutiny since school accountability became a hot topic during the 1980's. However, despite all the efforts to improve student productivity through a well defined curriculum, and possibly because of the increased emphasis on student accountability to reflect that student improvement, concern for the apparent declining creativity levels among students appears to be growing.
The purpose of this dissertation was to compare conventional instructional methodologies with those of creative problem solving. It was hypothesized that students' low, high, and total cognition levels, overall creativity levels, and satisfaction with instructional methodologies, improve as a result of instruction through creative problem solving strategies. By improving the levels of creativity within students, they will be better equipped to deal with the complex types of problems the future will present.
This study utilized an experimental, posttest only, control group design. Participants were ninth grade students (n=20) who were enrolled in an Introduction to World Agricultural and Science Technology I course. Posttests were administered to measure low, high, and total levels cognition at the conclusion of the course. For this measure of the dependent variable, a forty question (10 true/false, 25 multiple choice, and 5 short answer) test was administered. Pretests and posttests were administered to measure student creativity. A standardized Torrance Test of Creative Thinking (TTCT) was used as the measure of the dependent variable of creativity. Pretests, mid-tests, and posttests were used to measure student satisfaction. A satisfaction instrument developed by Brashears (2004) was used for the measurement of clarity, delivery, content, and total satisfaction as the dependent measure of satisfaction. These instruments were used to measure the five research hypotheses of the study.
Results of the study did not support the hypotheses that significant differences exist between creative problem solving and traditional instructional strategies, as they pertain to student cognition, creativity, and satisfaction. However, although not significant, possibly due to the small sample size, upon closer examination of group means, one can detect definite patterns of greater mean score gains among the CPS group over the traditional group in cognition, creativity, and satisfaction. Based on these findings, this researcher suggests that replications of this study be performed with larger sample sizes in different curriculum areas to further perpetuate the integration of creative problem solving strategies as an effective instructional strategy for all age groups and in all areas of the curriculum.
|
53 |
Vraisemblance empirique généralisée<br />et estimation semi-paramétriqueHarari-Kermadec, Hugo 05 December 2006 (has links) (PDF)
La vraisemblance empirique est une méthode d'estimation inspirée de la vraisemblance classique, mais s'affranchissant du choix d'une famille paramétrique de lois. Cette méthode semi-paramétrique consiste à maximiser la vraisemblance d'une loi ne chargeant que les données et permet de construire des régions de confiance lorsque le paramètre d'intérêt est défini à partir de contraintes de moments.<br />Dans cette thèse, nous généraliserons la méthode de vraisemblance empirique à une vaste gamme de méthodes de divergence empirique. Nous montrerons que l'on peut obtenir des résultats non asymptotiques originaux pour certaines divergences. Nous proposerons également une adaptation de la vraisemblance empirique aux chaînes de Markov. Nous mènerons deux applications : l'estimation d'un indice du risque d'exposition au méthylmercure, en combinant les diverses sources de données disponibles, et l'étude du rôle de la norme sociale sur le surpoids et l'obésité.
|
54 |
PHYLOGENOMIC APPROACHES TO THE ANALYSIS OF FUNCTIONAL DIVERGENCE AND SUBCELLULAR LOCALIZATIONGaston, Daniel 09 February 2012 (has links)
With rapid advances in sequencing technologies and precipitous decreases in cost, public sequence databases have increased in size apace. However, experimental characterization of novel genes and their products remains prohibitively expensive and time consuming. For these reasons, bioinformatics approaches have become increasingly necessary to generate hypotheses of biological function. Phylogenomic approaches use phylogenetic methods to place genes, chromosomes, or whole genomes within the context of their evolutionary history and can be used to predict the function of encoded proteins. In this thesis, two new phylogenomic methods and software implementations are presented that address the problems of subcellular localization prediction and functional divergence prediction within protein families respectively.
Most of the widely used programs for subcellular localization prediction have been trained on model organisms and ignore phylogenetic information. As a result, their predictions are not always reliable when applied to phylogenetically divergent eukaryotes, such as unicellular protists. To address this problem, PhyloPred-HMM, a novel phylogenomic method was developed to predict sequences that are targeted to mitochondria or mitochondrion-related organelles (hydrogenosomes and mitosomes). This method was compared to existing prediction methods using an existing test dataset of mitochondrion-targeted sequences from well-studied groups, sequences from a variety of protists, and the whole proteomes of two protists: Tetrahymena thermophila and Trichomonas vaginalis. PhyloPred-HMM performed comparably to existing classifiers on mitochondrial sequences from well-studied groups such as animals, plants, and Fungi and better than existing classifiers on diverse protistan lineages.
FunDi, a novel approach to the prediction of functional divergence was developed and tested on 11 biological datasets and two large simulated datasets. On the 11 biological datasets, FunDi appeared to perform comparably to existing programs, although performance measures were compromised by a lack of experimental information. On the simulated datasets, FunDi was clearly superior to existing methods. FunDi, and two other prediction programs, was then used to characterize the functional divergence in two groups of plastid-targeted glyceraldehyde-3-phosphate dehydrogenases (GAPDH) adapted to roles in the Calvin cycle. FunDi successfully identified functionally divergent residues supported by experimental data, and identified cases of potential convergent evolution between the two groups of GAPDH sequences.
|
55 |
Computational Gains Via a Discretization of the Parameter Space in Individual Level Models of Infectious DiseaseFANG, XUAN 13 January 2012 (has links)
The Bayesian Markov Chain Monte Carlo(MCMC) approach to inference is commonly used to estimate the parameters in spatial infectious disease models. However, such MCMC analyses can pose a hefty computational burden. Here we present new method to reduce the computing time cost in such MCMC analyses and study its usefulness. This method is based a round the discretization of the spatial parameters in the infectious disease model. A normal approximation of the posterior density of the output from the original model will be compared to that of the modified model, using the Kullback-Leibler(KL) divergence measure.
|
56 |
Investigations in Southeast Texas Precipitating Storms: Modeled and Observed Characteristics, Model Sensitivities, and Educational BenefitsHopper, Larry 2011 December 1900 (has links)
This dissertation establishes a precipitation climatology for common storm types and structures in southeast Texas, investigating diurnal, seasonal, and interannual rainfall variations in addition to climatological differences in raindrop size distributions and storm divergence profiles. Divergence profiles observed by an S-band, Doppler radar are compared to ensemble simulations of ten precipitating systems occurring in warm season, weakly baroclinic, and strongly baroclinic environments. Eight triply-nested mesoscale model simulations are conducted for each case using single- and double- moment microphysics with four convective treatments (i.e., two convective parameterizations and explicit vs. parameterized convection at 9 km). Observed and simulated radar reflectivities are objectively separated into convective, stratiform, and non-precipitating anvil columns and comparisons are made between ensemble mean echo coverages and levels of non-divergence (LNDs). In both the model and observations, storms occurring in less baroclinic environments have more convective rain area, less stratiform rain area, and more elevated divergence profiles.
The model and observations agree best for well-organized, leading-line trailing stratiform systems. Excessive convective rain area and elevated LNDs are simulated for several less organized cases. Simulations parameterizing convection on the intermediate grid produced less elevated divergence profiles with smaller magnitudes compared to their explicit counterparts. In one warm season case, double-moment microphysics generated lower LNDs associated with variations in convective intensity and depth, detraining less ice to anvil and stratiform regions at midlevels relative to a single-moment scheme. Similarly, mesoscale convective vortex simulations employing an ensemble-based versus a single-closure convective parameterization produced the least elevated heating structures (closer to observed) resulting in the weakest midlevel vortices.
Finally, this dissertation is unique in that some of the data collection and a portion of the analysis involved 95 undergraduates in a five-year research and education program, the Student Operational ADRAD Project (SOAP). In addition to documenting the program's structure and implementation, student-reported experiences, confidence, and interest in performing SOAP tasks are also analyzed. Students participating in SOAP for multiple years were significantly more confident in performing SOAP tasks, more likely to obtain science or meteorology-related employment upon graduation, and more likely to matriculate to graduate programs, suggesting programs like SOAP have a strong influence on students' career outcomes and self-efficacy.
|
57 |
Analytical, computational, and statistical approaches to studying speciationLemmon, Alan Richard, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.
|
58 |
Global Behavior Of Finite Energy Solutions To The Focusing Nonlinear Schrödinger Equation In d DimensionJanuary 2011 (has links)
abstract: Nonlinear dispersive equations model nonlinear waves in a wide range of physical and mathematics contexts. They reinforce or dissipate effects of linear dispersion and nonlinear interactions, and thus, may be of a focusing or defocusing nature. The nonlinear Schrödinger equation or NLS is an example of such equations. It appears as a model in hydrodynamics, nonlinear optics, quantum condensates, heat pulses in solids and various other nonlinear instability phenomena. In mathematics, one of the interests is to look at the wave interaction: waves propagation with different speeds and/or different directions produces either small perturbations comparable with linear behavior, or creates solitary waves, or even leads to singular solutions. This dissertation studies the global behavior of finite energy solutions to the $d$-dimensional focusing NLS equation, $i partial _t u+Delta u+ |u|^{p-1}u=0, $ with initial data $u_0in H^1,; x in Rn$; the nonlinearity power $p$ and the dimension $d$ are chosen so that the scaling index $s=frac{d}{2}-frac{2}{p-1}$ is between 0 and 1, thus, the NLS is mass-supercritical $(s>0)$ and energy-subcritical $(s<1).$ For solutions with $ME[u_0]<1$ ($ME[u_0]$ stands for an invariant and conserved quantity in terms of the mass and energy of $u_0$), a sharp threshold for scattering and blowup is given. Namely, if the renormalized gradient $g_u$ of a solution $u$ to NLS is initially less than 1, i.e., $g_u(0)<1,$ then the solution exists globally in time and scatters in $H^1$ (approaches some linear Schr"odinger evolution as $ttopminfty$); if the renormalized gradient $g_u(0)>1,$ then the solution exhibits a blowup behavior, that is, either a finite time blowup occurs, or there is a divergence of $H^1$ norm in infinite time. This work generalizes the results for the 3d cubic NLS obtained in a series of papers by Holmer-Roudenko and Duyckaerts-Holmer-Roudenko with the key ingredients, the concentration compactness and localized variance, developed in the context of the energy-critical NLS and Nonlinear Wave equations by Kenig and Merle. One of the difficulties is fractional powers of nonlinearities which are overcome by considering Besov-Strichartz estimates and various fractional differentiation rules. / Dissertation/Thesis / Ph.D. Mathematics 2011
|
59 |
Impact of financial and economic crisis on Spain: regional aspectsPaličková, Eva January 2015 (has links)
PALIČKOVÁ, Eva. Impact of Financial and Economic Crisis on Spain: Regional Aspects Brno, 2014. 117 p. Diploma thesis. Mendel University in Brno. Thesis deals with impact of financial and economic crisis on all seventeen regions and two cities in Spain. The main purpose of the thesis is to find out, whether the crisis influenced the development of convergence or divergence between Spanish regions. First of all the complete overview of economic development on basis of the most important macroeconomic indicators during ten-year period for each region was done. Afterwards, the statistical method, Cluster analysis, was performed for two different time periods dividing crisis period, which facilitated diagrams capturing regional grouping and their movements during different crisis period. Additionally, the Beta-convergence analysis was performed. Also the Beta-convergence analysis was run in three different time periods, which results revealed nicely the evolution of convergence and divergence be-tween Spanish regions during last ten-years marked by crisis situation.
|
60 |
Caracterização agromorfológica e reação ao mofo cinzento de acessos de mamoneira / Agromorphological characterization and gray mold reaction of castor bean accessionsOliveira Neto, Sebastião Soares de [UNESP] 04 July 2017 (has links)
Submitted by SEBASTIÃO SOARES DE OLIVEIRA NETO null (neto.soliver@gmail.com) on 2017-08-14T19:21:28Z
No. of bitstreams: 1
Oliveira Neto, S. S. - Dissertação.pdf: 1803281 bytes, checksum: e617e725a28292660d7b2535bb1546b1 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-08-22T16:48:24Z (GMT) No. of bitstreams: 1
oliveiraneto_ss_me_bot.pdf: 1803281 bytes, checksum: e617e725a28292660d7b2535bb1546b1 (MD5) / Made available in DSpace on 2017-08-22T16:48:24Z (GMT). No. of bitstreams: 1
oliveiraneto_ss_me_bot.pdf: 1803281 bytes, checksum: e617e725a28292660d7b2535bb1546b1 (MD5)
Previous issue date: 2017-07-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A mamoneira (Ricinus communis L.) é uma oleaginosa da família das Euforbiáceas que disseminou-se por varias regiões do mundo devido a sua fácil propagação e adaptação. O principal produto negociado no mercado internacional é o óleo de rícino e o Brasil é o segundo maior fornecedor desse produto. O melhoramento vegetal visando à obtenção de novas cultivares e híbridos de mamoneira é primordial para o sucesso econômico da cultura, pois, o plantio de materiais mais produtivos, resistentes à doenças e que permitem o uso de mecanização traz maior retorno econômico para os produtores. O objetivo do presente estudo foi realizar a caracterização agromorfológica, avaliar a divergência genética e a reação ao mofo cinzento de 58 acessos de mamoneira coletados em diferentes regiões do Brasil. Realizou-se a criação de um banco de sementes de mamoneiras selvagens através de coletas em diversas regiões do Estado de São Paulo, Sul de Minas Gerais e na capital do Rio Grande do Norte. As sementes foram levadas para o Departamento de Produtividade e Melhoramento Vegetal da Faculdade de Ciências Agronômicas (FCA) em Botucatu – SP para beneficiamento e realização de testes preliminares (vigor, germinação e teor de óleo). Os acessos pré-selecionados foram semeados e caracterizados através de 31 descritores morfológicos. Foram coletados racemos desses materiais para testar a reação e a resistência ao mofo cinzento da mamoneira no Laboratório de Entomologia e Fitopatologia da Embrapa Meio Ambiente em Jaguariúna-SP conforme metodologia específica. Os dados obtidos nas avaliações foram submetidos à análise de variância, análise de similaridade pelo método hierárquico do vizinho mais próximo e análise de componentes principais. A maior porcentagem de germinação (98,67%) foi obtida pelos acessos BTC5, SAP1 e SBS2. Foram selecionados como fonte de resistência ao mofo cinzento da mamoneira, os acessos SM2, SAP4, SM1, SBS2, SJC2, BOIT1, CBJ1, BOF2, BTC5 e CJ4. O acesso BOC1 foi considerado o mais divergente. Os acessos SM2, SM1, SBS2, CJ4, BTC4, CJ3, CJ1, CBJ1, CJ6, SAP2, SAP1 e SAP4 possuem características agromorfológicas de interesse comercial e são promissores para constituírem uma coleção de germoplasma em programas de melhoramento genético da mamoneira. / Castor bean (Ricinus communis L.) is an an Euphorbiaceae family oilseed that has spread to various regions of the world due to its easy propagation and adaptation. Brazil is the second largest castor oil supplier, the main product traded in the international market. Plant breeding to generate cultivars and hybrids more productive, resistant to diseases, allowing the use of mechanization of castor bean can drive this crop for the economic success, generating producer's profit. Our aim was to perform the agro-morphological characterization, evaluate genetic divergence and gray mold reaction of 58 accessions of castor bean collected in different regions of Brazil. A wild castor bean seed bank was created through collections in several São Paulo State regions, South of Minas Gerais and in the capital of Rio Grande do Norte. Processing and preliminary tests (vigor, germination and oil content) were performed at the Department of Productivity and Plant Breeding from Faculty of Agronomic Sciences (FCA) in Botucatu, SP, Brazil. Preselected accessions were sown and characterized by 31 morphological descriptors. Castor bean racemes were tested to gray mold reaction and resistance in the Laboratory of Entomology and Phytopathology, Embrapa Meio Ambiente in Jaguariúna-SP, Brazil. Variance analysis, similarity by the nearest neighbor hierarchical method and principal components analysis was performed on all data obtained. BTC5, SAP1 and SBS2 showed the highest germination percentage (98.67%). SM2, SAP4, SM1, SBS2, SJC2, BOIT1, CBJ1, BOF2, BTC5 and CJ4 were selected as the resistance source of the castor bean gray mold while BOC1 was the most divergent. SM2, SM1, SBS2, CJ4, BJC4, CJ3, CJ1, CBJ1, CJ6, SAP2, SAP1 and SAP4 have agro-morphological characteristics of commercial interest and they are promising to constitute a germplasm collection in castor bean breeding programs.
|
Page generated in 0.0647 seconds