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Nonlinear Finite Element Analysis of the Black River Bridge - A Serviceability StudyZaeem, Mohammed Rizwan H. 11 December 2013 (has links)
An attempt was made to predict the service life of the Black River Bridge using non-linear finite element analysis (NLFEA). Numerical modeling was performed using NLFEA software developed by Prof. Evan Bentz.
A large number of analytical studies were conducted to assess the strength and behaviour of the bridge under normal truck loading and at failure loads. It was determined that the bridge is shear critical. Location of trucks that would cause maximum deflection and highest crack widths were identified. It is believed that these findings will have a significant impact on physical measurements that can be incorporated into future bridges, helping researchers determine the locations in the bridge that are ideal for instrumentation.
Axial compression present in the bridge can significantly affect deflection and crack widths. Incorporating thermal and shrinkage effects into the NLFEA are recommended as topics for further research. Appropriate estimate of thermal and shrinkage strain will aid in better prediction of axial stresses.
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Facies Architecture and Stratigraphy of Tidal Ridges in the Eocene Roda Formation, Northern SpainMichaud, Kain 02 May 2011 (has links)
ABSTRACT
The Eocene Roda Formation in northern Spain documents the deposits from a range of coastal depositional environments. These include alluvial plains, distributary channels, mouth bars, upper to lower-shorefaces, and tidal shelf ridges. Eighteen progradational sand tongues that are interpreted as parasequences compose two third-order sequences. Sequence 1 accumulated in an environment with strong tidal currents and high rates of progradation, while Sequence 2 was deposited under relatively weaker currents and higher rates of aggradation, which produced a higher mudstone:sandstone ratio.
The stratigraphy highlights the transgressive origin of six tidal shelf ridges, three in each sequence, that overlie regressive deltaic tongues. Sequence 1 shelf ridges are composed almost entirely of cross-bedded sandstones, whereas Sequence 2 ridges are composed of a mixture of cross-bedded and ripple-laminated deposits. Ridges in both sequences contain bioturbation that is typical of the Cruziana Ichnofacies, and that indicates a marine origin.
The tidal ridges are stratigraphically located at or near the point of maximum third-order regression, and are not found within early highstand or late transgressive deposits― times of high relative sea level when the deltaic shoreline did not protrude significantly. Tidal currents were accentuated at the coast when the delta complex had prograded several kilometres into the basin, while during times of high relative sea level, the basin was wider and tidal currents were weaker, consequently leading to a lack of tidal deposits. The tidal ridges are, thus, interpreted as being headland-associated deposits. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2011-04-29 17:10:10.008
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Study of the dynamics of barred early type galaxies via numerical simulationsLablanche, Pierre-Yves 04 April 2012 (has links) (PDF)
Since the 30's and Edwin Hubble's famous classification, galaxies are usually separated in twogroups : the late-type galaxies (LTGs) and the early-type galaxies (ETGs). The LTGs family ismainly made of spiral galaxies (S) while the ETGs family is composed of elliptical (E) and lenticular(S0) galaxies. A morphological study of all these galaxies revealed that around 60% of LTGs and45% of S0 present a bar. It has also been shown that, in the local Universe, galaxies fall into twobig groups : the blue cloud mostly populated by LTGs and the red sequence mainly made of ETGs.Several mechanisms are responsible for this distribution and the secular evolution is obviously animportant one to examine, sepcially in the context of bars, as an important number of studiesshowed the importance of bars in the dynamics and evolution of a galaxy.The goal of my thesis is to study the importance of the formation and ensued bar-drivenevolution influence on ETGs evolution. In that context, I have performed N-body simulations ofbarred (and unbarred) galaxies in order to investigate the following issues.First of all, I focused on the influence of a bar in a galaxy when modelling it with a dynamicalmodel assuming an axisymmetric mass distribution. As these kinds of models allow to determine themass-to-light ratio M/L, thus the dynamical mass of an observed galaxy, but also its inclinationand its anisotropy, it is important to evalute the consequence of the presence of a bar on theseparameters. I have shown that, depending on the galaxy inclination and the bar position angle,M/L is most of the time biased and overestimated, and this can be up to 25%. The size andstrength of the bar also seem to be important factors but a deeper study has to be done to quantifythis preliminary result.In a second step, I have studied the role of bars on the mass and metallicity redistributionsin a lenticular galaxy. I confirmed that the presence of a bar, due to its influence on its hostsystem dynamics, flattens pre-existing metallicity gradients. Moreover, I showed that the degree offlattening and the position of affected regions are directly correlated with the bar structure and thelocation of the dynamical resonances. Nonetheless, this dynamical effect cannot explain the varietyof observed ages and metallicity gradients. The consequences of a barred gravitational potentialon the gas dynamics and the stellar formation should therefore be investigated. This is the topicof the last set of numerical simulations produced which will allow to better understand the globalinfluence a bar has on the secular evolution of ETGs.
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Nonlinear Finite Element Analysis of the Black River Bridge - A Serviceability StudyZaeem, Mohammed Rizwan H. 11 December 2013 (has links)
An attempt was made to predict the service life of the Black River Bridge using non-linear finite element analysis (NLFEA). Numerical modeling was performed using NLFEA software developed by Prof. Evan Bentz.
A large number of analytical studies were conducted to assess the strength and behaviour of the bridge under normal truck loading and at failure loads. It was determined that the bridge is shear critical. Location of trucks that would cause maximum deflection and highest crack widths were identified. It is believed that these findings will have a significant impact on physical measurements that can be incorporated into future bridges, helping researchers determine the locations in the bridge that are ideal for instrumentation.
Axial compression present in the bridge can significantly affect deflection and crack widths. Incorporating thermal and shrinkage effects into the NLFEA are recommended as topics for further research. Appropriate estimate of thermal and shrinkage strain will aid in better prediction of axial stresses.
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Anwendung der Thermomechanischen Behandlung mit Wärmebehandlung aus der Walzhitze für die Herstellung der Stabstahlsorte 15MnCrMoV4-8Voloskov, Sergey 20 February 2014 (has links) (PDF)
Zur Herstellung von Stabstahl der Sorte 15MnCrMoV4-8 ist die thermomechanische Behandlung erprobt worden. Diese erfolgte in Kombination mit der kosten- und energiesparenden Wärmebehandlung aus der Walzhitze. Dabei wurde besondere Aufmerksamkeit der chemischen Zusammensetzung gewidmet. Sie wird aus der Sicht kostenintensiver Legierungselemente, wie sie in Kombination mit Umformung und Abkühlung zum Erreichen eines mechanischen Eigenschaftsprofils führen, betrachtet. Das erforderliche Niveau der mechanischen Eigenschaften ist aus der Anwendung dieser Stahlsorte für die Fertigung von Pumpenstangen aus dem Bereich der Ölfördernden Industrie abgeleitet worden.
Bei den entwickelten und erprobten Herstellungstechnologien haben ein Teil der Stahlstäbe der gewählten Legierungen das geforderte Eigenschaftsniveau von Halbzeugen für die ölfördernde Industrie erreicht. Ein Teil davon hat sogar das Eigenschaftsprofil einer höheren Festigkeitsklasse, die zu Gewichts- und Energieeinsparungen führt. Die angestrebte Lebensdauer, ermittelt durch Schwingfestigkeitstests unter atmosphärischen Bedingungen sowie im korrosiv-wässrigen 3%NaCl-Medium, ist bei fast allen untersuchten Werkstoffen erreicht worden.
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Development Of Algorithms For Fault Detection In Distribution SystemsErsoi, Moustafa 01 December 2003 (has links) (PDF)
In this thesis, the possibility of detection of fault location in the cable distribution
systems by using traveling waves due to fault and circuit breaker operations is
investigated. Waveforms originated from both actions and fault steady state are
separately analyzed.
During such switching actions, high frequency variations which are absent in the
steady state conditions, take place. In order to simulate high frequency changes
properly, system elements are modeled accordingly. In other words, frequency
dependent models are introduced, and they are used in Electro-Magnetic Transients
Program (EMTP).
Since the characteristics of waveforms are different for separately analyzed
portions, different fault locating algorithms with their limitations are introduced.
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[en] DEVELOPMENT OF MICROALLOYED STEEL FOR THE PRODUCTION OF REBAR / [pt] DESENVOLVIMENTO DE AÇO MICROLIGADO PARA A PRODUÇÃO DE VERGALHOES NERVURADOSLEONARDO MIRANDA NUNES 18 January 2018 (has links)
[pt] O desenvolvimento de um aço microligado para a produção de vergalhões
nervurados, busca atender a modernização das estruturas de concreto armado e
a industrialização na construção civil que solicitam novos desenvolvimentos nas
técnicas de construção e nos materiais aplicados. As barras de aço nervuradas
são um dos principais produtos empregados na produção de peças e estruturas
de concreto armado sendo usadas largamente por todo o mundo. A otimização
da aplicação final, a necessidade de manter baixos custos de produção e
atender a combinação de alta resistência com grande ductilidade em um material
com características de soldabilidade destinados a armaduras de concreto
armado, se tornou um grande desafio para os produtores de vergalhões para a
construção civil. Aplicando a tecnologia desenvolvida ao longo dos últimos 50
anos, este trabalho oferece a alternativa de se empregar aços microligados ao
vanádio e nióbio para a produção em laminadores de alta produção de rolos de
vergalhões capazes de atender a indústria da construção civil nos mais rigorosos
atributos solicitados. Os experimentos foram realizados em escala industrial
testando aços com faixa de 0,14 porcento a 0,20 porcento de vanádio e até 0,04 porcento de nióbio.
Os resultados atendem as normas mais exigentes no mercado mundial. / [en] The development of microalloyed steel for the production of reinforcement
bars (rebar) seeks to achieve the modernization of reinforced concrete structures
and streamline industrialization in civil construction that demands new
developments in techniques and applied materials. Rebar is one of the main
products used in the production of reinforced concrete all over the world. The
optimization of the final application and the necessity to keep production low
costs while attempting to combine high resistance with great ductility in a material
with weldability characteristics, became a great challenge for the producers of
rebars. Applying the technology developed throughout the last 50 years, this work
offers the alternative of using vanadium and niobium microalloyed steel to
produce large quantities of rebars in rolling mills. Upon completion these rebar
are used in coils capable of meeting the most rigorous demands of the civil
construction industry. The experiments made in an industrial environment,
applied steels with 0.14 percent to 0.20 percent of vanadium and up to 0.04 percent of niobium. The
results met the most demanding standards in the world-wide market.
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Structures spatiales déployables constituées de mètres rubans : analyse et implémentation de modèles de poutre à section flexible / Deployable space structures made up of tape springs : analysis and implementation of rod models with flexible cross-sectionMartin, Maverick 08 December 2017 (has links)
Les mètres rubans sont utilisés comme dispositif de déploiement car ils sont légers, compacts, se déploient de manière autonome et ont une capacité d'auto-blocage en position déployée. Ces structures élancées de forme cylindrique présentent un comportement complexe avec formation de plis localisés. Leur modélisation est donc difficile : bien que des modèles de poutre à section flexible (RFleXS) aient été développés. Les travaux réalisés consistent à développer des outils numériques d'aide au dimensionnement de structures déployées par des rubans. Un modèle RFleXS adimensionné dédié aux rubans peu profonds est introduit et analysé, mettant en évidence des liens avec le modèle de barre d'Ericksen régularisé. Ces liens expliquent la formation de plis et caractérisent les trois zones constitutives d'un pli. On détermine de façon analytique le nombre et la position des points de bifurcation des branches de solution obtenues pour un essai de flexion pure d'un ruban. Un enrichissement de la cinématique de section est intégré dans les modèles RFleXS. Les simulations de flexion de ruban montrent alors une bonne corrélation avec les modèles de coque. Une nouvelle formulation des modèles RFleXS est implémentée et conduisant au développement de deux outils numériques : un code de calcul par éléments finis complet et un élément à deux noeuds intégré dans un code commercial. Des essais de flexion réalisés sur des rubans composites viennent compléter ces travaux afin de confronter les simulations numériques à des essais réels. Bien que des écarts soient observés, le comportement global du ruban est bien retranscrit par les modèles de poutre à section flexible. / Due to their lightness, compactness, their autonomous deployment and their ability to self-locking while deployed, tape-springs are considered to deploy structures. These slender and cylindrical structures highlight a complex behaviour because of the formation of localised folds. Tape-springs are then difficult to model but a rod model with flexible cross-section (RFleXS) has been developed in order to characterise the tape-spring behaviour.The purpose of this PhD was to develop numerical tools dedicated to design structures deployed by tape-spings. A dimensionless form of the RFleXS model dedicated to shallow tape spring has been developed and links with a regularised Ericksen's bar have been made. These links help to explain folds creation and to determine characteristics of the three constitutive areas of a fold. Analysis of the dimensionless model leads to determine the finite number and the position of bifurcation points for the pure bending of a tape-spring. The cross-section kinematic is enriched; simulations of bending tests then show a good correlation with shell models. A new implementation of RFleXS models is introduced, leading to the creation of two numerical tools: a full finite element software and a one-dimensional element with two nodes incorporated in Abaqus. Some bending experiments have been performed in order to compare simulations with measured data. Even if discrepancies are observed, these comparisons show that the tape-spring overall behaviour is well predicted by rod models with flexible cross-section.
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Étude du comportement des hydrocarbures aromatiques polycycliques (HAP) lors du déversement accidentel d'hydrocarbures en eaux continentales / Polycyclic aromatic hydrocarbons behavior study during accidental oil spill in continental watersPimsee, Pranudda 17 July 2014 (has links)
L’application de la Directive Cadre sur l’Eau et l’obligation de surveillance de la qualité de l'eau pour la consommation humaine et les activités industrielles entraînent une forte demande pour des systèmes d’évaluation et de suivi de la qualité de l’eau. Le projet de recherche MIGR'HYCAR (http://www.migrhycar.com) a donc été mis en place pour répondre à un besoin opérationnel et à un défaut d'outils d'aide à la décision adaptés face aux déversements d'hydrocarbures en eaux continentales (rivières, lacs et estuaires) qui représentent plus de 50% des déversements accidentels en France. Ce travail de thèse s'inscrit dans le cadre de ce projet et a pour but l’étude du comportement des nappes d'hydrocarbures en milieu contrôlé pour les eaux continentales. A cet effet, il propose une approche expérimentale à l’échelle laboratoire pour étudier les phénomènes agissant sur une nappe d'hydrocarbures déversée : dissolution, étalement, évaporation et volatilisation. Les données expérimentales réunis ont permis de constituer une base de données de référence, qui servira de support aux outils de modélisation mathématique de dérive de nappe d'hydrocarbures développés dans le cadre de ce projet. / The application of the European Water Framework Directive on water quality for human consumption and industrial activities creates a need for water quality assessment and monitoring systems. The MIGR'HYCAR research project (http://www.migrhycar.com) was initiated to provide decisional tools for risks connected to oil spills in continental waters (rivers, lakes and estuaries), which represent more than 50% of accidental spills in France. This work joins within the framework of this project and aims at the study of the behavior of hydrocarbons in a controlled environment for continental waters. For that purpose, the work proposes an experimental approach at laboratory scale to study the phenomena acting in oil spill: dissolution, spreading, evaporation and volatilization. The experimental data allowed establishing a reference database, which will serve as support in tools of oil spill modeling within the framework of this project.
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Resolução de problemas da pré-álgebra e álgebra para fundamental II do ensino básico com auxílio do modelo de barrasQueiroz, Jonas Marques dos Santos 17 October 2014 (has links)
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Previous issue date: 2014-10-17 / The difficulties in learning and teaching of algebra can be detected in the school cycle 4 (8th and 9th grades) of the Elementary School II and throughout High School, such difficulties being present in all Brazilian schools. These difficulties arise from an institutional failure, in others words, in the transition from arithmetic to algebra, in the phase of pre-algebra which occurs at cycle 3 ( 6th and 7th grades) of the Elementary School II. When this transition is unsatisfactory this compromises the subsequent studies making the students feel not motivated in learning the content of algebra. Therefore, in this research project we planned and executed 6 (six) activities based on the methodology of Problem Solving based on the phases proposed by George Polya, along with the methodology of the Bar Model from Singapore Mathematics. The activities were carried out in seventh grade classrooms of Elementary School II of Instituto Educacional Estilo , Campinas, SP. The results of this dissertation suggests to teachers of Elementary School II didactical sequences of activities that they can use and enjoy in classroom practices, so that they can improve also their teaching and learning, contributing to the development of the students. With the objective of achieving a satisfactory transition from arithmetic to algebra, the activities were developed and based on problems solving, and then analyzed critically using the Problem Solving steps. After 6 (six) activities, we applied a diagnostic evaluation in order to analyze the results and to check if the activities contributed to a meaningful learning of algebra. The dissertation presents a theoretical study about teaching and learning algebra as well as a study on the methodologies of Problem Solving in classroom practice and Bar Model from Singapore Mathematics. / As dificuldades na aprendizagem e no ensino da álgebra podem ser constatadas no ciclo 4 (8º Ano e 9º Ano) do Ensino Fundamental II e também em todo o Ensino Médio, tais dificuldades estão presentes em todas as escolas brasileiras. Essas dificuldades são decorrentes de uma falha na introdução, ou seja, na transição da aritmética para a álgebra, a pré-álgebra que ocorre no final do ciclo 3 (6º Ano e 7º Ano) do Ensino Fundamental II, já que feita de maneira não satisfatória pode comprometer as aulas seguintes fazendo com que os alunos se sintam desmotivados a aprenderem o conteúdo de álgebra. Deste modo foram planejadas e executadas 6 (seis) atividades utilizando a metodologia de Resolução de Problemas seguindo as etapas de George Polya, juntamente com a metodologia do Modelo de Barras segundo a Filosofia da Matemática de Singapura. As atividades foram aplicadas em duas turmas do sétimo ano do Ensino Fundamental II, no colégio Instituto Educacional Estilo, Campinas, SP. O trabalho desenvolvido nesta dissertação proporciona aos professores do Ensino Fundamental II e Ensino Médio uma sequência didática, que podem utilizar e aproveitar em suas aulas de forma que possam também melhorar em suas práticas de ensino e aprendizagens, de maneira a contribuir para o desenvolvimento de seus alunos. Com o objetivo de realizar uma transição satisfatória da aritmética para álgebra, as atividades foram elaboradas e baseadas na resolução de problemas, e depois analisadas criticamente por meio das etapas de resolução. Após as 6 (seis) atividades, aplicamos uma avaliação diagnóstica de forma a analisar os resultados para verificar se as atividades contribuíram com significado para uma aprendizagem da álgebra. O trabalho apresenta um estudo teórico sobre o ensino e aprendizagem da álgebra e também apresenta um estudo sobre as metodologias desenvolvidas no trabalho, Resolução de Problemas e Modelo de Barras segundo a Filosofia da Matemática de Singapura.
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