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  • 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.
221

Ecologia trófica em arroios de baixa ordem do sul do Brasil: relação entre consumidores primários e secundários / Trophic ecology of low-order streams in southern Brazil: relationships between primary and secondary consumers

Barbosa, Amanda Saldanha 25 February 2015 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-06-05T16:57:51Z No. of bitstreams: 1 Amanda Saldanha Barbosa.pdf: 1110620 bytes, checksum: ca79658c72904b34bd463d8a587dbd0e (MD5) / Made available in DSpace on 2015-06-05T16:57:51Z (GMT). No. of bitstreams: 1 Amanda Saldanha Barbosa.pdf: 1110620 bytes, checksum: ca79658c72904b34bd463d8a587dbd0e (MD5) Previous issue date: 2015-02-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / UNEMAT - Universidade do Estado de Mato Grosso / O conceito de rio continuo (RCC) afirma que ocorrem alterações das características físicas e químicas ao longo do gradiente longitudinal de arroios, o que induz ao acréscimo de espécies de diferentes hábitos alimentares. Neste sentido o objetivo deste estudo é a caracterização trófica de espécies de peixes de cabeceira de arroios subtropicais e a identificação do fluxo de energia entre macroinvertebrados e peixes. Espera-se que a biomassa de peixes detritívoros aumente conforme o gradiente longitudinal, devido ao aumento da produção primaria neste sentido. O estudo foi desenvolvido em 32 sítios de 1ª a 4ª ordem pertencentes a oito microbacias da Bacia do Rio dos Sinos. As coletas de ictiofauna foram realizadas utilizando pesca elétrica em uma área de 100m2. Macroinvertebrados foram coletados com amostrador Surber, para avaliar a disponibilidade de recurso e biomassa de consumidores primários. A riqueza e a diversidade da comunidade íctica foram calculadas. Foi avaliada a dieta das espécies de peixes mais abundantes e calculados os índices de importância relativa e de amplitude de nicho. Para verificar a transferência de energia entre consumidores primários e secundários foi quantificada a biomassa seca de peixes e macroinvertebrados. Os resultados demonstram que a diversidade, a riqueza e a biomassa aumentaram conforme o gradiente longitudinal que arroios de cabeceira, corroborando as previsões do RCC. Também constatou-se que a comunidade íctica é composta por duas guildas alimentares (insetívoros e detritívoros). Estes últimos, por sua vez, elevaram a biomassa íctica e estabeleceram duas vias de fluxo de energia atuando como consumidores primários e secundários. / The River Continuum Concept (RCC) suggests that changes in physico-chemical factors across the stream longitudinal gradient leads to the adding of species of different feeding habits. In this sense, the aim of the study is the trophic characterization of fish headwater species from subtropical streams and to identify energy flow between macroinvertebrate and fishes. It is expected that detritivorous fish standing crop increase across stream longitudinal gradient due to increase in primary production in the same direction. This study was carried out in 32 streams from 1st to 4thorder in eight microbasins in the Sinos River basin. Ichthyofauna was sampled with electric fishing in 100m2 sections. Macroinvertebrates were sampled with Surber sampler to assess resource availability and primary consumer standing crop. Richness and diversity of fish communities were also calculated. The diet of the most abundant fish species was assessed as well as relative importance and niche amplitude indexes. The results displayed that fish diversity, richness and standing crop increased across stream longitudinal gradient corroborating RCC postulates. It was also indicated that fish communities was composed by two feeding groups (insetivorous and detritivorous). The detritivorous fishes have in turn increased fish standing crop and established two directions of energy flow which act as both primary and secondary consumers.
222

Contribution to the improvement of meshless methods applied to continuum mechanics / Contribution à l’amélioration des méthodes sans maillage appliquées à la mécanique des milieux continus

Fougeron, Gabriel 02 October 2018 (has links)
Cette thèse présente un cadre général pour l’étude de schémas de discrétisation nodaux sans maillageformulé en termes d’opérateurs discrets définis sur un nuage de points : intégration volumique et de bord, gradientet opérateur de reconstruction. Ces définitions dotent le nuage de points d’une structure plus faible que celledéfinie par un maillage, mais partageant avec elle certain concepts fondamentaux. Le plus important d’entre euxest la condition de compatibilité intégro-différentielle. Avec la consistance linéaire du gradient discret, cet analoguediscret de la formule de Stokes constitue une condition nécessaire à la consistance linéaire des opérateurs elliptiquesen formulation faible. Sa vérification, au moins de manière approchée, permet d’écrire des discrétisations dont le tauxde convergence est optimal. La construction d’opérateurs discrets compatibles est si difficile que nous conjecturons– sans parvenir à le démontrer – qu’elle nécessite soit la résolution d’un système linéaire global, soit la constructiond’un maillage : c’est "la malédiction sans-maillage". Trois grandes approches pour la construction d’opérateursdiscrets compatibles sont étudiées. Premièrement, nous proposons une méthode de correction permettant de calculerl’opérateur gradient compatible le plus proche – au sens des moindres carrés – sans mettre à mal la consistancelinéaire. Dans le cas particulier des gradients DMLS, nous montrons que le gradient corrigé est en réalité globalementoptimal. Deuxièmement, nous adaptons l’approche SFEM au cadre opérateur et constatons qu’elle définit desopérateurs consistants à l’ordre un et compatibles. Nous proposons une méthode d’intégration discrète exploitantla relation topologique entre les cellules et les faces d’un maillage qui préserve ces caractéristiques. Troisièmement,nous montrons qu’il est possible de générer tous les opérateurs sans maillage rien qu’avec la donnée d’une formuled’intégration volumique nodale en exploitant la dépendance fonctionnelle des poids volumiques nodaux par rapportà la position des noeuds du nuage, l’espace continu sous-jacent et le nombre de noeuds. Les notions de consistance desdifférents opérateurs sont caractérisées en termes des poids volumiques initiaux, formant un jeu de recommandationpour la mise au point de bonnes formules d’intégration. Dans ce cadre, nous réinterprétons les méthodes classiquesde stabilisation de la communauté SPH comme cherchant à annuler l’erreur sur la formule de Stokes discrète.L’exemple des opérateurs SFEM trouve un équivalent en formulation volume, ainsi que la méthode d’intégrationdiscrète s’appuyant sur un maillage. Son écriture nécessite toutefois une description très précise de la géométriedes cellules du maillage, en particulier dans le cas où les faces ne sont pas planes. Nous menons donc à bienune caractérisation complète de la forme de telles cellules uniquement en fonction de la position des noeuds dumaillage et des relations topologiques entre les cellules, permettant une définition sans ambigüité de leur volume etcentre de gravité. Enfin, nous décrivons des schémas de discrétisation d’équations elliptiques utilisant les opérateurssans-maillage et proposons plusieurs possibilités pour traiter les conditions au bord tout en imposant le moinsde contraintes sur la position des noeuds du nuage de points. Nous donnons des résultats numériques confirmantl’importance capitale de vérifier les conditions de compatibilité, au moins de manière approchée. Cette simple recommandation permet dans tous les cas d’obtenir des discrétisations dont le taux de convergence est optimal. / This thesis introduces a general framework for the study of nodal meshless discretization schemes. Itsfundamental objects are the discrete operators defined on a point cloud : volume and boundary integration, discretegradient and reconstruction operator. These definitions endow the point cloud with a weaker structure than thatdefined by a mesh, but share several fundamental concepts with it, the most important of them being integrationdifferentiationcompatibility. Along with linear consistency of the discrete gradient, this discrete analogue of Stokes’sformula is a necessary condition to the linear consistency of weakly discretized elliptic operators. Its satisfaction, atleast in an approximate fashion, yields optimally convergent discretizations. However, building compatible discreteoperators is so difficult that we conjecture – without managing to prove it – that it either requires to solve a globallinear system, or to build a mesh. We dub this conjecture the "meshless curse". Three main approaches for theconstruction of discrete meshless operators are studied. Firstly, we propose a correction method seeking the closestcompatible gradient – in the least squares sense – that does not hurt linear consistency. In the special case ofMLS gradients, we show that the corrected gradient is globally optimal. Secondly, we adapt the SFEM approachto our meshless framework and notice that it defines first order consistent compatible operators. We propose adiscrete integration method exploiting the topological relation between cells and faces of a mesh preserving thesecharacteristics. Thirdly, we show that it is possible to generate each of the meshless operators from a nodal discretevolume integration formula. This is made possible with the exploitation of the functional dependency of nodal volumeweights with respect to node positions, the continuous underlying space and the total number of nodes. Consistencyof the operators is characterized in terms of the initial volume weights, effectively constituting guidelines for thedesign of proper integration formulae. In this framework, we re-interpret the classical stabilization methods of theSPH community as actually seeking to cancel the error on the discrete version of Stokes’s formula. The example ofSFEM operators has a volume-based equivalent, and so does its discrete mesh-based integration. Actually computingit requires a very precise description of the geometry of cells of the mesh, in particular in the case where its facesare not planar. We thus fully characterize the shape of such cells, only as a function of nodes of the mesh andtopological relations between cells, allowing unambiguous definition of their volumes and centroids. Finally, wedescribe meshless discretization schemes of elliptic partial differential equations. We propose several alternatives forthe treatment of boundary conditions with the concern of imposing as few constraints on nodes of the point cloudas possible. We give numerical results confirming the crucial importance of verifying the compatibility conditions,at least in an approximate fashion. This simple guideline systematically allows the recovery of optimal convergencerates of the studied discretizations.
223

Análise de estruturas de edifício alto submetidas a carregamento sísmico pela técnica do meio contínuo / Analysis of tall building structures under eartquake loading for continuous medious technique

Orozco Donneys, Carlos Andrés 25 November 2015 (has links)
Historicamente os engenheiros desenvolveram técnicas alternativas de análise de estruturas visando facilitar essa parte do processo de projeto que sempre é enjoada. Médio Contínuo (MC) é uma delas cujo emprego é factível em estágios iniciais do projeto. Etapas nas quais é preciso contar com uma ideia mesmo que bastante aproximada das dimensões dos diversos elementos da estrutura. No MC a abordagem da estrutura tridimensional é feita através da consideração das rigidezes planas dos diferentes elementos constituintes. É dizer, aquela rigidez que opõe-se ao carregamento contido no próprio plano do elemento. Os deslocamentos originários de carregamento lateral são obtidos como uma razão força/rigidez. Neste trabalho é abordada a Técnica do Médio Contínuo com carregamento dinâmico originário do sismo, com aplicação específica para os edifícios de certa envergadura, no entanto deixando em aberto uma futura pesquisa para atingir alturas maiores com outros sistemas estruturais além de se abrir um panorama de possibilidades com escopo de refinar este trabalho como a adopção de outro método mais requintado de análise sísmica, tal como a metodologia modal que sem dúvida é mais geral e está sujeita a menores restrições. / Historically, engineers have been developed alternative structural analysis techniques in order of facilitate this part of the design of process which is always difficult. Continuum medious (MC) it´s one theses whose use is feasible in the early stages of the project. Steps in which is necessary have an ideia that even very approximate dimensions of the various elements of the structure. In MC approach , the three dimensional structure is made considering the flat stiffness. That is, a stiffness oppose the load contained in the plane of element itself. The displacements are obtained as a ratio force/stiffness. The work is interesting com dynamical loading originating from the earthquake with specific application to the buildings medium tallest. Howewer futures research to achieve greater heights with other structural systems as well open up a panorama de possibilities with scope to improve this work as the adoption of a more refined method of seismic analysis, such as modal methodology that certainly is more general and is subject to fewer restrictions.
224

A questão étnico-racial na formação continuada de professores da Escola Básica: uma análise de quatro Núcleos de Estudos Afrobrasileiros do estado do Rio de Janeiro / The ethnic-racial question in the continuum training of primary education teachers: analysing four Núcleos de Estudos Afrobrasileiros of Rio de Janeiro state

Sergio Gonçalves de Lima 18 September 2012 (has links)
O presente estudo teve como objetivo geral analisar em que medida os Núcleos de Estudos Afrobrasileiros(Neabs) contribuem com o processo de formação continuada de professores da Escola Básica e, como objetivos específicos: analisar a história, os dilemas e as práticas político-pedagógicas que marcam a criação e trajetória de quatro Neabs no estado do Rio de Janeiro, à luz das definições de multiculturalismo; e identificar os elementos que se aproximam e os que se distanciam, nas concepções e intervenções desses Neabs, a partir da avaliação dos seus/as coordenadores/as. Como suporte teórico se ancorou nas contribuições de McLaren (1997), a respeito das distintas vertentes de multiculturalismo e, DAdesky (2001), sobre pensar o múltiplo a raciocinar a partir de categorias que são indeterminadas ou pouco determinadas, como raça, etnia e nação. A pesquisa buscou responder quais têm sido os desdobramentos no campo da educação étnico-racial, conduzidos pelos Neabs, para a formação continuada de professores da Escola Básica, no estado do Rio de Janeiro. A pesquisa se pautou numa abordagem qualitativa dentro do paradigma crítico e, se apoiou em análise documental e em técnicas de entrevista semi-estruturada. Foram entrevistados quatro coordenadores de Neabs do estado do Rio de Janeiro. O estudo possibilitou compreender que são inúmeras as dificuldades encontradas pelos Neabs para a realização de suas propostas, tais como as de caráter governamental e institucional. Dentre vários aspectos, mostrou a defesa dos participantes por uma proposta política, de caráter emergencial, com objetivos de publicar pesquisas produzidas pelos próprios Neabs. As análises puderam mostrar, também, que existe uma má gestão dos recursos do Programa UNIAFRO pelas universidades. Contudo, é possível afirmar que os Neabs têm como perspectiva o multiculturalismo critico, na medida em que compreendemos que as representações são o resultado de lutas sociais sobre significantes e seus significados. É possível conceber que o viés do multiculturalimo crítico, apropriado pelos Neabs, traz contribuições significativas conquistadas pelos movimentos sociais, que dão visibilidade às formas pelas quais os diferentes grupos sociais constroem a sua história
225

Continuum psicofísico : uma abordagem baseada no pensamento de Charles S. Pierce /

Pires, Jorge Luiz Vargas Prudêncio de Barros. January 2002 (has links)
Orientador: Lauro Frederico Barbosa da Silveira / Banca: Adolpho Menezes de Mello / Banca: Alfredo Pereira Júnior / Resumo: O presente trabalho propõe uma discussão a respeito da fisiologia do músculo esquelético humano como um processo de caráter sígnico. Trata-se de uma abordagem interdisciplinar para se estudar as relações biológicas baseada no pensamento de Charles S. Peirce. Diferente das aproximações mecanicistas e reducionistas, que entendem o ser vivo como uma máquina cartesiana, a tendência semiótica busca uma abordagem mais ampla sobre as fundações da biologia, liberando o pensamento e lançando nova luz nas investigações dos seres vivos. Tal estudo poderá contribuir no entendimento das relações psicofísicas do corpo por considerar os músculos uma ampla esfera de processos mentais. Este texto inicia-se com uma discussão a respeito da natureza da conduta muscular. Na segunda parte do texto, examinar-se-á a conduta muscular como um hábito baseado na experiência. Na terceira parte, a relação entre causação final e eficiente na conduta muscular será examinada a seguir, e na quarta parte, o fenômeno da indeterminação na contração muscular. Na quinta parte, será discutida a relação entre o hábito autocontrolado do músculo e os três tipos de raciocínio proposto por Peirce: Abdução, Dedução e Indução. O modelo triádico do signo permite-nos observar na conduta muscular uma ampla esfera de atividades racionais, mostrando-nos que o músculo possui as mais elevadas e refinadas propriedades de uma mente que aprende com a experiência. Assim não há motivos suficientemente fortes ou logicamente sustentados para reivindicar qualquer privilégio à racionalidade humana. / Abstract: This contribution proposes an analysis the human skeletal muscle physiology as a sign process, based on Charles S. Peirce's thought. It contributes to understand the psychophysical relations in the human body by considering muscles an including sphere of mental processes. This paper first discusses the nature of muscular conducts. Following Peirce's Objective Idealism, it is argued that muscle contraction is a typically mental process. It is general and eidetic. In the second part, the muscular physiological conduct is discussed as experience based habits, anticipated by Peirce. In the third part, the relation between final and efficient causation in muscular conduct is examined, and in the fourth part, the phenomena of indeterminacy in muscular contraction. It is argued that objective chance is the only responsible for originating spontaneous and original muscular conducts. In a fifth part, one discusses the relation between the acquired auto-controlled muscular habit and the three different types of reasoning proposed by Peirce: Abduction, Deduction and Induction. One concludes raising the hypothesis that the basis of all muscular cell conduct is evolutionary rationality. The triadic model of Sign proposed by Peirce allows us to observe a wider rationality in muscular conduct. It shows us the higher and refined properties of a Mind that learns by experience. / Mestre
226

Reflexão de funções cardinais / Reflection of cardinal functions

Alberto Marcelino Efigênio Levi 15 June 2012 (has links)
Neste trabalho investigamos problemas sobre reflexão de funções cardinais, fazendo uso de técnicas como submodelos elementares e Teoria PCF. Mostramos que o grau de Lindelöf reflete todos os cardinais fortemente inacessíveis e que um exemplo de espaço onde a mesma função cardinal não reflita um cardinal fracamente inacessível requer a existência de 0#. Além disso, estendemos um resultado de reflexão do caráter, de espaços Lindelöf para espaços linearmente Lindelöf, obtendo novas equivalências com a Hipótese do Contínuo (CH). Obtivemos ainda várias respostas parciais para problemas clássicos deste tópico de pesquisa. / This work investigates problems about reflection of cardinal functions, using techniques such as elementary submodels and PCF Theory. We show that the Lindelöf degree reflects all the strongly inaccessible cardinals and that a example of a space in which the same cardinal function does not reflect a weakly inaccessible cardinal requires \"0# exists\". Furthermore, we extend a result of reflection of the character from Lindelöf spaces to linearly Lindelöf spaces, obtaining new equivalences with the Continuum Hypothesis (CH). We also obtained several partial answers to classic problems of this research topic.
227

Elagage d'un arbre de Lévy - Diffusion aléatoire en milieu Lévy / Pruning of a Lévy tree - Random diffusion in a Lévy environment

Voisin, Guillaume 02 December 2009 (has links)
Se donnant un mécanisme de branchement critique ou sous-critique, on définit une procédure d’élagage de l’arbre aléatoire continu de Lévy associé. Cette procédure d’élagage est définie en plaçant des marques sur l’arbre grâce `a des techniques de serpent de Lévy. On démontre alors que le sous-arbre obtenu après élagage est encore un arbre aléatoire continu de Lévy. Ce résultat est démontré en utilisant une propriété de Markov spéciale et un problème de martingale pour les processus d’exploration. On construit ensuite, par couplage, une autre procédure d’élagage qui définit un processus de fragmentation sur l’arbre. On calcule la famille de mesures de dislocation associée à cette fragmentation. Dans un deuxième travail, on considère une diffusion aléatoire dans un milieu Lévy stable. On montre que le processus des temps locaux renormalisé et recentré au minimum de la vallée standard de hauteur log t, converge en loi vers une fonctionnelle de deux processus de Lévy conditionnés `a rester positifs indépendants. Pour démontrer ce résultat, on montre que la loi de la vallée standard est proche de celle de deux processus de Lévy conditionnés à rester positifs concaténés en 0. On obtient également la loi limite du supremum du temps local renormalisé. / Given a general critical or sub-critical branching mechanism, we define a pruning procedure of the associated Lévy continuum random tree. This pruning procedure is defined by adding some marks on the tree, using Lévy snake techniques. We then prove that the resulting sub-tree after pruning is still a Lévy continuum random tree. This last result is proved using the exploration process that codes the CRT, a special Markov property and martingale problems for exploration processes. We then construct, by coupling, an another pruning procedure which define a fragmentation process on the tree. We compute the family of dislocation measures associated with this fragmentation. In a second work, we consider a one-dimensional diffusion in a stable Lévy environment. We show that the normalized local time process refocused at the bottom of the standard valley with height log t converges in law to a functional of two independent Lévy processes conditioned to stay positive. To prove this result, we show that the law of the standard valley is close to a two-sided Lévy process conditioned to stay positive. We also obtain the limit law of the supremum of the normalized local time.
228

CORRELATION BETWEEN EMISSION LINES AND RADIO LUMINOSITIES OF ACTIVE GALACTIC NUCLEI

Short-Long, Jessica 01 January 2018 (has links)
Radio-loud active galactic nuclei (AGN) are one class of objects associated with accretion activity onto supermassive black holes in centers of massive galaxies. They are believed to be in a radiatively-inefficient accretion mode with low accretion rate. To understand this accretion mode, it is important to measure its radiative output at high energies (> 13.6eV), which can be traced through optical emission lines. However, little is known about their true radiative output. This is because no correlation between optical emission-line and radio luminosity has been found for the majority of low-luminosity radio AGN, which are often classified as low-excitation radio galaxies, or Fanaroff-Riley Class I (FR-I) radio galaxies. We demonstrate that most of the line emission found in these galaxies is not powered by the central AGN, but likely powered by some old stellar population. Only when this component is subtracted or otherwise taken into account can we estimate the true line emission associated with the AGN. These emissions may show interesting correlations with the radio luminosities in some cases.
229

PATHWAY CONNECTIVITY IN AN EPIGENETIC FLUVIOKARST SYSTEM: INSIGHT FROM A NUMERICAL MODELLING STUDY IN KENTUCKY USA

Adams, Ethan 01 January 2019 (has links)
Fluviokarst landscapes are dominated by both fluvial and karst features. Interpreting hydrologic pathways of fluviokarst can be confounded by the unknown connectivity of the various flow regimes. A combined discrete-continuum (CDC) hybrid numeric model for simulating the surface and subsurface hydrology and hydraulics in fluviokarst basins was formulated to investigate fluviokarst pathways. This model was applied to the Cane Run Royal Springs basin in Kentucky USA. A priori constraints on parameterization were avoided via multi-stage optimization utilizing Sobol sequencing and high performance computing. Modelling results provide evidence of hydrologic pathways dominated by fracture flow, epikarst transfer and runoff. Fractures in karst basins with high fracture-matrix permeability ratios may influence both springflow and streamflow. Swallet features can be as important as spring features as they are sink features in streamflow during hydrologic events. Inflections in spring hydrographs represent shifts in the surface-subsurface connectivity via the fractures, as opposed to shifts in dominant storage zones. Existing methods of dual- and triunal hydrograph separation of karst springflow may not be directly transferrable to fluviokarst springs. The numerical model herein has advantages of suggesting dominant pathways in complex terrane and highlighting unforeseen surface-subsurface connectivity. However, disadvantages include computational expense and previous site studies.
230

Secrets of the Spearhead : Developing Continuum Mechanical Simulations and Organic Residue Analysis for the Study of Scandinavian Flint Spearhead Functionality

Lundström, Fredrik January 2019 (has links)
This thesis is a pilot study, designed to test and develop methods suitable for the study of Scandinavian flint spearhead functionality. The functionality of projectile and lithic point armament has not been studied for almost 30 years in Scandinavia. Meanwhile, methods used to analyse lithic projectiles have developed considerably. However, few of these methods are precise enough to be used in conjunction with Scandinavian stone technological analyses that emphasize the societal aspect of lithic points. Consequently, two methods were chosen that could provide data for Scandinavian research issues: 3D-scanning/continuum mechanical simulations and organic residue analysis. The methods were tested on 6 experimental spearheads. The continuum mechanical simulation generated both visual and numerical data that could be used to create precise functional-morphological descriptions. The data could also potentially be used for projectile point classification. The organic residue analysis revealed promising results for the use of an artefact and activity specific analysis, with a sequential extraction protocol. In unison, the results from both analyses could be used to reveal how spearheads were functionally designed and used in Stone Age Scandinavia, even though there are methodological and technological issues that need solving.

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