• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 26
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 46
  • 46
  • 18
  • 13
  • 8
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Sobre o uso de subestruturas na modelagem de estruturas complexas. / On the use of substructures in complex structures modeling.

Lucas Anastasi Fiorani 24 April 2009 (has links)
Na engenharia, existem diversas técnicas de análise estrutural que conduzem à obtenção de esforços e deslocamentos com considerável grau de eficácia e acurácia e, dentre estas, há a técnica de SUBESTRUTURAÇÃO. Esta técnica consiste na divisão e análise de um modelo estrutural completo, através da divisão de seu domínio em SUBESTRUTURAS, permitindo uma considerável eficiência nos cálculos e na avaliação de modelos estruturais combinados com a análise hierárquica de estruturas. Neste trabalho, seguindo-se a metodologia de pesquisa, que envolveu revisão bibliográfica e desenvolvimento de modelos computacionais, apresentaram-se as principais técnicas de subestruturas - seção 1, definições e formulação teórica dos principais métodos - desenvolvidos por Przemienieck (1963), Rosen e Rubinstein (1968), Rubinstein (1970) e El-Sayed e Hsiung (1990) - e a conceituação da análise hierárquica de estruturas com as respectivas aplicações combinadas com técnica de subestruturação para análise de fissuras em estruturas aeronáuticas, proposta de Starnes e Britt (1991) e aplicada por Potyondy (1993) - seção 2. Nesse contexto, na seção 3 se propôs a metodologia hierárquica para análise de estruturas típicas da construção civil, utilizando técnicas de subestruturação. Apresentaram-se instrumentos úteis à respectiva aplicação, dentre os quais se destaca a proposta de metodologia simplificada de análise hierárquica. Algumas precauções a serem adotadas na aplicação da metodologia também foram apresentadas. Na seção 4, desenvolveram-se cinco estudos de caso aplicando-se as metodologias, instrumentos e precauções desenvolvidos na seção 3, destacando-se a eficácia das metodologias. Conclui-se a pesquisa na seção 5 sendo que, na seção 6, indicam-se novas linhas de pesquisas a serem desenvolvidas sobre a metodologia proposta na pesquisa. / In engineering, there are several structural analysis techniques leading to obtain displacements and efforts with a considerable degree of efficacy and accuracy, and, among these, there is the SUBSTRUCTURING technique. This method consists in the division and analysis of a complete structural model, by subdividing his field in SUBSTRUCTURES, allowing a considerable efficiency in calculations and evaluation of structural models combined with hierarchical structures analysis. In this work, following the methodology research, which involved a literature review and computational models development, the key techniques of substructures were presented - section 1, as well as main methods definitions and theoretical formulation - developed by Przemienieck (1963), Rosen and Rubinstein (1968), Rubinstein (1970) and El-Sayed and Hsiung (1990) - and structural hierarchical analysis concept with their applications combined with aircraft structures cracks substructuring technical analysis, proposed by Starnes and Britt (1991), and implemented by Potyondy (1993) - Section 2. In this context, a civil construction typical structures analysis methodology was proposed in section 3. Besides, many useful tools for their implementation were presented, among which stands out the simplified hierarchy analysis methodology proposal. Some precautions in the methodology applying were also presented. In section 4, five case studies were developed, applying the methodology, tools and precautions explained in section 3, especially the methodologies effectiveness. The research is concluded in section 5, and new research lines, to be undertaken on the methodology proposed, were outpointed in section 6.
42

Conditionnement des stratégies d'histoire de vie en condition naturelle et mécanismes adaptatifs à court terme : approche intégrée par capture-marquage-recapture et application au saumon atlantique (Salmo salar) / Conditional life-history strategies and short-term adaptive mechanisms : an integrated approach using mark-recapture data with application to wild Atlantic salmon (Salmo salar)

Buoro, Mathieu 05 December 2011 (has links)
Pour comprendre l'origine des variations d'histoire de vie des organismes, il fautétudier et mettre en évidence les stratégies d'histoire de vie et les processus évolutifsqui les gouvernent. Ce travail de thèse a pour objectif d'étudier les stratégiesd'histoire de vie et leur conditionnement par les caractéristiques individuellesen conditions naturelles. Les stratégies d'histoire de vie sont vues comme un agencementde normes de réactions et de compromis évolutifs. Cependant, l'étude desprocessus évolutifs en milieu naturel se heurte à des problèmes d'ordre méthodologique.En effet, le suivi exhaustif au cours du temps d'individus d'une populationest difficilement réalisable, voire impossible en conditions naturelles. Les méthodesde capture-marquage-recapture permettent une observation partielle des histoires devie et des traits d'histoire de vie. Ce travail se base sur l'idée que nos observationsne sont que la partie visible de processus sous-jacents qu'il est nécessaire de prendreen compte pour ne pas biaiser nos inférences statistiques. J'utilise la modélisation àstructure cachée pour 1) séparer le processus d'observation du processus dynamiqued'intérêt, 2) modéliser les histoires de vie complètes des individus, 3) intégrer dansun cadre unique et cohérent les décisions d'histoire de vie et les compromis évolutifset 4) représenter explicitement les mécanismes sous-jacents qui génèrent nos observations.Dans ce cadre, on peut alors intégrer les théories et concepts de la biologieévolutive dans l'analyse statistique des données d'observations. J'illustre ce travailpar l'étude du conditionnement des stratégies d'histoire de vie dans une populationnaturelle de saumon Atlantique sur le Scorff (Morbihan) à partir de données de CMR.Mes résultats mettent en évidence des décisions d'histoire de vie statut-dépendanteset des compromis évolutifs qui n'auraient pas pu être mis en évidence hors du cadrede modélisation proposé. / Understanding the origin of life history variations of organisms requires studying life historystrategies and evolutionary processes that drive them. This thesis aims at studying life historystrategies under natural conditions and how they are conditioned by individual characteristics.Life history strategies are seen as a combination of reaction norms and evolutionarytrade-offs. The study of evolutionary processes in the wild faces to methodological issues.Indeed, the exhaustive monitoring of individuals over time is often impossible in the wild.Capture-mark-recapture methods allow a partial observation of life histories and life historytraits. This work was based on the idea that our observations are only the visible part ofunderlying processes that need to be accounted for to limit the risk of flawed statistical inferences.I resort to hidden structure modeling to 1) separate the observation process fromthe dynamic process of interest, 2) model the full life histories of individuals, 3) integratewithin a single and coherent framework life history decisions and evolutionary trade-offs and4) explicitly represent the underlying mechanisms that generate our observations. Withinthis framework, one can confront theories and concepts in evolutionary biology with observationaldata through appropriate statistical tools. Finally, I illustrate this work by studying theconditioning of life-history strategies in a natural population of Atlantic salmon on the Scorffriver (Morbihan) using CMR data. My results highlight status-dependent life history decisionsand evolutionary trade-offs that could not be identified without our proposed modelingframework.
43

Relation entre le traitement maternel en bas âge et la régulation de la tristesse à huit ans : une étude de jumeaux

Paul-Hus, Adèle 08 1900 (has links)
La présente étude porte sur les aspects Nature-Culture relatifs à l’émergence de variations interindividuelles quant à la capacité universelle de régulation d’une émotion primaire, la tristesse. Cette problématique représente un exemple du lien entre la conception évolutionniste d’une nature humaine universelle, innée et génétiquement prescrite, mais susceptible de variation dans son expression en fonction d’expériences individuelles liées aux processus de socialisation et d’enculturation. À l’aide du devis génétiquement informatif des jumeaux, nous nous sommes d’abord penchés sur l’étiologie gènes-environnement de la dépression à l’enfance, une dysfonction du système de régulation émotionnelle de la tristesse. Puis, nous nous sommes interrogés quant à l’influence du traitement et de l’état psychique maternels sur cet aspect du développement émotionnel de l’enfant. Nos analyses de la symptomatologie dépressive indiquent une absence d’influence génétique dans le développement de ce trouble de l’humeur. Les variations individuelles de la régulation de la tristesse reposent ainsi uniquement sur les effets de l’environnement. Nos résultats révèlent également l’existence d’une relation importante entre l’état psychique de la mère, évalué lorsque les jumeaux avaient cinq mois, et la présence de symptômes dépressifs chez ces derniers mesurés huit ans plus tard. L’état psychique de la mère est considéré comme l’un des meilleurs indicateurs de la qualité du traitement maternel en bas âge. Nos mesures directes des comportements maternels envers le nourrisson et le développement ultérieur du trouble de dépression indiquent également l’existence de tendances statistiques allant dans le sens de notre hypothèse d’un traitement maternel sous-optimal contribuant au développement de dysfonctions émotionnelles ultérieures. / The present study explores the Nature-Nurture aspects pertaining to the emergence of interindividual variation in the emotional regulation of a primary emotion, sadness. This question is an example of the more encompassing issue of a universal human nature, biologically evolved and genetically underwritten, being nevertheless variable in its expression depending on individual experiences linked to socialization and enculturation. Using a genetically informative twin design, we explored the genetic-environmental aetiology of child depression, which is understood to be a dysfunction in the emotional regulation system of sadness. We then assessed the influences of maternal behavior and mental state on the development of children’s depressive symptoms. Our analysis of child depression shows an absence of genetic influence in the emergence of this mood disorder. Thus, individual variation in sadness regulation appears to be solely generated by environmental influences. Our results also show a strong and significant relation between maternal psychological state, assessed when the twins were 5 months of age, and children’s depressive symptoms measured 8 years later. Maternal psychological state is considered to be one of the most reliable indicators of the quality of maternal treatment in childhood. Our direct measures of maternal behavior toward the infant and the subsequent development of depressive disorder also point to statistical trends supporting our hypothesis of suboptimal maternal treatment contributing to the development of later emotional dysfunction.
44

Relation entre le traitement maternel en bas âge et la régulation de la tristesse à huit ans : une étude de jumeaux

Paul-Hus, Adèle 08 1900 (has links)
La présente étude porte sur les aspects Nature-Culture relatifs à l’émergence de variations interindividuelles quant à la capacité universelle de régulation d’une émotion primaire, la tristesse. Cette problématique représente un exemple du lien entre la conception évolutionniste d’une nature humaine universelle, innée et génétiquement prescrite, mais susceptible de variation dans son expression en fonction d’expériences individuelles liées aux processus de socialisation et d’enculturation. À l’aide du devis génétiquement informatif des jumeaux, nous nous sommes d’abord penchés sur l’étiologie gènes-environnement de la dépression à l’enfance, une dysfonction du système de régulation émotionnelle de la tristesse. Puis, nous nous sommes interrogés quant à l’influence du traitement et de l’état psychique maternels sur cet aspect du développement émotionnel de l’enfant. Nos analyses de la symptomatologie dépressive indiquent une absence d’influence génétique dans le développement de ce trouble de l’humeur. Les variations individuelles de la régulation de la tristesse reposent ainsi uniquement sur les effets de l’environnement. Nos résultats révèlent également l’existence d’une relation importante entre l’état psychique de la mère, évalué lorsque les jumeaux avaient cinq mois, et la présence de symptômes dépressifs chez ces derniers mesurés huit ans plus tard. L’état psychique de la mère est considéré comme l’un des meilleurs indicateurs de la qualité du traitement maternel en bas âge. Nos mesures directes des comportements maternels envers le nourrisson et le développement ultérieur du trouble de dépression indiquent également l’existence de tendances statistiques allant dans le sens de notre hypothèse d’un traitement maternel sous-optimal contribuant au développement de dysfonctions émotionnelles ultérieures. / The present study explores the Nature-Nurture aspects pertaining to the emergence of interindividual variation in the emotional regulation of a primary emotion, sadness. This question is an example of the more encompassing issue of a universal human nature, biologically evolved and genetically underwritten, being nevertheless variable in its expression depending on individual experiences linked to socialization and enculturation. Using a genetically informative twin design, we explored the genetic-environmental aetiology of child depression, which is understood to be a dysfunction in the emotional regulation system of sadness. We then assessed the influences of maternal behavior and mental state on the development of children’s depressive symptoms. Our analysis of child depression shows an absence of genetic influence in the emergence of this mood disorder. Thus, individual variation in sadness regulation appears to be solely generated by environmental influences. Our results also show a strong and significant relation between maternal psychological state, assessed when the twins were 5 months of age, and children’s depressive symptoms measured 8 years later. Maternal psychological state is considered to be one of the most reliable indicators of the quality of maternal treatment in childhood. Our direct measures of maternal behavior toward the infant and the subsequent development of depressive disorder also point to statistical trends supporting our hypothesis of suboptimal maternal treatment contributing to the development of later emotional dysfunction.
45

Hierarchical Spatial and Spatio-Temporal Modeling of Massive Datasets, with Application to Global Mapping of CO<sub>2</sub>

Katzfuss, Matthias 12 September 2011 (has links)
No description available.
46

Development of Traffic Safety Zones and Integrating Macroscopic and Microscopic Safety Data Analytics for Novel Hot Zone Identification

Lee, JaeYoung 01 January 2014 (has links)
Traffic safety has been considered one of the most important issues in the transportation field. With consistent efforts of transportation engineers, Federal, State and local government officials, both fatalities and fatality rates from road traffic crashes in the United States have steadily declined from 2006 to 2011.Nevertheless, fatalities from traffic crashes slightly increased in 2012 (NHTSA, 2013). We lost 33,561 lives from road traffic crashes in the year 2012, and the road traffic crashes are still one of the leading causes of deaths, according to the Centers for Disease Control and Prevention (CDC). In recent years, efforts to incorporate traffic safety into transportation planning has been made, which is termed as transportation safety planning (TSP). The Safe, Affordable, Flexible Efficient, Transportation Equity Act - A Legacy for Users (SAFETEA-LU), which is compliant with the United States Code, compels the United States Department of Transportation to consider traffic safety in the long-term transportation planning process. Although considerable macro-level studies have been conducted to facilitate the implementation of TSP, still there are critical limitations in macroscopic safety studies are required to be investigated and remedied. First, TAZ (Traffic Analysis Zone), which is most widely used in travel demand forecasting, has crucial shortcomings for macro-level safety modeling. Moreover, macro-level safety models have accuracy problem. The low prediction power of the model may be caused by crashes that occur near the boundaries of zones, high-level aggregation, and neglecting spatial autocorrelation. In this dissertation, several methodologies are proposed to alleviate these limitations in the macro-level safety research. TSAZ (Traffic Safety Analysis Zone) is developed as a new zonal system for the macroscopic safety analysis and nested structured modeling method is suggested to improve the model performance. Also, a multivariate statistical modeling method for multiple crash types is proposed in this dissertation. Besides, a novel screening methodology for integrating two levels is suggested. The integrated screening method is suggested to overcome shortcomings of zonal-level screening, since the zonal-level screening cannot take specific sites with high risks into consideration. It is expected that the integrated screening approach can provide a comprehensive perspective by balancing two aspects: macroscopic and microscopic approaches.

Page generated in 0.1212 seconds