A sociedade vem questionando os conteúdos presentes no currículo de ciências, quanto ao \"por que\" e \"para que\" ensiná-los. Isso ocorre também dentro do ambiente escolar. Atualmente, o ensino de ciências tem acontecido de maneira bastante desconexa da realidade de nossos alunos, afinal, este ensino não tem apresentado inovações ou trazido temas atualizados para as discussões que ocorrem no ambiente da sala de aula. Apresentamos neste trabalho uma proposta de atualização curricular do ensino de ciências através da inserção de tópicos de Física Moderna e Contemporânea, com base na proposta curricular inserida nos PCNEM e PCNEM+ para a disciplina de Física. Nossa proposta consiste em uma seqüência didática de um curso de Física das Radiações voltado ao Ensino Médio, onde se utilizam as noções de \"marcadores\" e \"marcadores-estruturantes\", desenvolvidas no contexto da teoria da Transposição Didática, para delinear as atividades que acreditamos serem essenciais para que esta nova seqüência de ensino seja exeqüível. / The society has questioned what should be taught in science learning, including both \"why\" and \"what for\" some subjects should be taught. This kind of discussion occurs also inside the educational environment. Presently the science teaching is not connected to the reality of the student, because teaching has not related to scientific innovations, no updated themes are discussed in the classroom. In this work the curricular updating is inserted through the inclusion of Modern and Contemporary Physics topics, as suggested in the PCNEM and PCNEM+. This proposal consists of a didactic sequence of a course on Radiations Physics appropriated to the high school teaching. The concept of \"markers\" and \"structurating-markers\" is discussed within the Didactic Transposition Theory. \"Markers\" are established through the proposed activities, which are supposed to be the essential ones to the learning sequence.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-10-31Bitstream added on 2014-06-13T19:55:35Z : No. of bitstreams: 1 garcia_am_me_ilha.pdf: 659750 bytes, checksum: 7318de4cdef56cfcd2a84f0bc10c3fbb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho propõe uma metodologia de ajuste de modelos de elementos finitos aplicado a problemas de contato. O ajuste do modelo é realizado através da atualização dos parâmetros físicos e/ou geométricos do modelo bem como dos parâmetros dos elementos de contato. O método utilizado é baseado nas FRF(s) e é formulado a partir de um resíduo de entrada, dado pelo balanço de força do sistema. Um software é implementado para fazer a comparação e correlação dos modelos analítico e experimental, e se necessário, ajustar os parâmetros do modelo analítico. O modelo analítico é gerado pelo software comercial ANSYSâ, e os dados experimentais são obtidos em testes experimentais de análise modal. A metodologia foi avaliada com exemplos numéricos e testes experimentais buscando identificar as potencialidades e limitações do método. Dois testes experimentais foram realizados. O primeiro teste consiste em obter os parâmetros modais de uma estrutura simples do tipo viga. No segundo teste, os parâmetros modais são obtidos de uma estrutura composta por duas peças em contato. O objetivo do primeiro teste é avaliar a potencialidade da metodologia proposta utilizando uma base de dados experimental confiável, já que a estrutura é simples e suas propriedades são bem conhecidas. O segundo teste tem por objetivo avaliar a metodologia para o problema de contato. Os resultados apresentados mostram a funcionalidade da metodologia. O ajuste foi realizado com êxito tanto para a estrutura simples como para a estrutura composta por duas peças em contato. / The present work proposes a finite element model updating methodology applied to problems of contact. The updating of the models is accomplished through the updating of the physical and/or geometric parameters of the model as well as the parameters of the contact elements. The approach is a FRF-based method; it is formulated from input residue, given by the equilibrium force of the system. It is implemented a software to makes the comparison and correlation of the analytical and experimental models, and if necessary, to adjust the parameters of the analytic model based in the experimental data, in order to get a more reliable finite element model. The analytical model is created by the commercial software ANSYSâ, and the experimental data are obtained by experimental modal tests. The methodology was evaluated with numeric and experimental data aiming at identifying of the potentialities and limitations of the method. Two experimental tests were developed, the first test consists of the analyses of a beam like structure and the second one, the analysis of a structure composed by two pieces in contact. The aim of the first test is to evaluate the potentiality of the methodology using a reliable experimental base of data, since the structure is simple and its properties are very wellknown. The second test has for objective to evaluate the methodology for problems of contact. The presented results have shown the functionality of the methodology. The adjustment was accomplished with relative success for the simple structure as well as for the structure composed by two pieces in contact.

An embedded system is an application-specific system that is typically dedicated to performing a particular task. Majority of embedded systems are also real-time, implying that timeliness in the system need to be enforced. An embedded system needs to be enforced efficient management of a large amount of data, including maintenance of data freshness in an environment with limited CPU and memory resources. Uniform and efficient data maintenance can be ensured by integrating database management functionality with the system. Furthermore, the resources can be utilized more efficiently if the redundant calculations can be avoided. On-demand updating and active behavior are two solutions that aim at decreasing the number of calculations on data items in embedded systems. COMET is a COMponent-based Embedded real-Time database, developed to meet the increasing requirements for efficient data management in embedded real-time systems. The COMET platform has been developed using a novel software engineering technique, AspeCtual COmponent-based Real-time software Development (ACCORD), which enables creating database configurations, using software components and aspects from the library, based on the requirements of an application. Although COMET provides uniform and efficient data management for real-time and embedded systems, it does not provide support for on-demand and active behavior. This thesis is focusing on design, implementation, and evaluation of two new COMET configurations, on-demand updating of data and active behavior. The configurations are created by extending the COMET component and aspect library with a set of aspects that implement on-demand and active behavior. The on-demand updating aspect implements the ODDFT algorithm, which traverses the data dependency graph in the depth-first manner, and triggers and schedules on-demand updates based on data freshness in the value domain. The active behavior aspect enables the database to take actions when an event occurs and a condition coupled with that event and action is fulfilled. As we show in the performance evaluation, integrating on-demand and active behavior in COMET improves the performance of the database system, gives a better utilization of the CPU, and makes the management of data more efficient.

This master’s thesis deals with the optimization of the process of corrective and preventive actions management in OTIS Escalators s.r.o. under ISO 9001:2000, ISO 14001:2005 and OHSAS 18001:1999 standards. Standards mentioned above are used to describe analyse of the process, which leads to several steps for successful optimization of the process.

Most tyre models developed to date require a fair amount of data before an accurate representation of the tyre can be obtained. This study entails the development of a simplified, yet accurate, non-linear Finite Element (FE) model of an “off-road” tyre to study the behaviour of the tyre due to radial loading conditions. The study aims to develop a FE tyre model that can solve fast and be accurate enough to be used in multibody dynamic vehicle simulations. A model that is less complex than conventional detailed FE models is developed. The work explores the use of superimposed finite elements to model the varying stiffness in the respective orthogonal directions of the sidewall and tread of the tyre. Non-linear elements defined by Neo-Hookean or Ogden models and elements with different linear orthogonal stiffnesses are superimposed onto each other to simulate the global material properties of the tread and the sidewall of the tyre investigated. The geometry of the tyre studied was measured experimentally using laser displacement transducers and digital image correlation techniques. Material properties of segments of the tyre were obtained by performing tensile tests on samples. Since the rubber slipped against the clamps during the experiment, deformation of the segments was also measured using digital image correlation. These geometrical and material properties were used as input to develop a finite element model of an “off-road” tyre. Measurements were conducted using laser displacement transducers, load cells mounted to actuators, etc. to obtain accurate sidewall deformation profiles and global radial load vs. displacement curves for different radial loading conditions. The data obtained from the results was used to validate the tyre model developed. Numerous analyses are performed with different combinations of moduli of elasticity in the respective orthogonal directions of the sidewall stiffness and the tread to investigate its influence on the global behaviour of the tyre model. The main focus of the project was to develop a tyre model from data obtained from laser and photogrammetry measurements in a laboratory that accurately represents tyre behaviour due to radial forces. A finite element model that can simulate the effect of radial forced and obstacles on a tyre was developed. The use of two subsets of elements, superimposed onto each other to simulate global material properties of the rubbers, steel wires, polyester and nylon threads, was investigated. The combination of material properties that gave the best fit for all the load cases investigated were determined. The finite element model correlated well with the load vs. displacement graphs and sidewall displacement profiles determined experimentally. The solving time is still fairly high and is still not quite suitable for real-time dynamic simulation. However, it solves faster than more complex tyre models where details of steel wires, etc. are included in the model. For future studies it is recommended that different element types be investigated in the tyre model. The study proves that equivalent material properties can be used to simulate the composite properties of the materials in tyres. Most tyres can be divided into a few regions that each has its own material structure right through the region. These regions can be characterized by simple tests and the input can be used as a first estimation of the tyre’s material properties for the model. Accurate validation criteria should be used to validate the tyre model if time does not allow for excessive testing of the material properties of all the rubber, steel wires, polyester threads, etc. Geometric displacement data at various loading conditions can be used for validation of the tyre model. The model developed can be used to investigate the effect of different stiffnesses and other material changes in the sidewall or tread of a tyre. Useful insight can be obtained from the finite element model developed for dynamic simulation where the force vs. global displacement data is important. / Dissertation (MEng)--University of Pretoria, 2014. / tm2015 / Mechanical and Aeronautical Engineering / MEng / Unrestricted

Cette thèse avait pour objectif de mettre en place et d’appliquer les techniques de mesure de champs de déplacements et de déformations (corrélation d’images numériques CIN) pour caractériser le comportement mécanique non linéaire de matériaux réfractaires. L’étude a été réalisée sur différents types de matériaux présentant des degrés variables de flexibilité : un matériau modèle monophasé à base de titanate d’aluminium (TA VF) et des matériaux industriels multi-phasés à base de magnésie. La flexibilité dans le cas du TA VF est obtenue grâce à l’anisotropie de la dilatation thermique entre les trois axes cristallographiques, et dans le cas des matériaux industriels grâce à la différence de coefficients de dilatation entre les agrégats de spinelle et la matrice magnésienne. Ces matériaux industriels ayant une déformation à rupture plus faible, la technique de corrélation d’images a dû être optimisée en ajustant au mieux les conditions expérimentales.La CIN et la méthode de suivi de marqueurs ont permis de mettre en évidence le caractère dissymétrique du comportement mécanique en flexion du TA VF entre la zone de l’éprouvette sollicitée en traction et celle en compression et d’investiguer le déplacement relatif des rouleaux du dispositif de flexion. Cette dissymétrie de comportement engendre un déplacement progressif de la fibre neutre au fur et à mesure que la charge appliquée augmente. Cette technique a ensuite été étendue à d’autres essais tels que l’essai brésilien et le Wedge Splitting appliqués aux matériaux industriels magnésiens. La CIN a ainsi permis d’illustrer les mécanismes de rupture (initiation et propagation de fissures) et de mettre en évidence la présence de phénomènes de « crack branching » obtenus grâce au réseau initial de microfissures volontairement généré au sein du matériau par différentiel de dilatation entre phases dans le but d’améliorer sa résistance aux chocs thermiques. Enfin, à partir des champs de déplacements obtenus par corrélation d’images, la méthode de recalage par éléments finis a été développée et utilisée pour déterminer l’évolution des propriétés élastiques du matériau pendant l’essai. / The present thesis aimed to apply digital image correlation (DIC) used for kinematic fields’ measurements as a support for the experimental characterization of refractory materials with specific non-linear behaviour. Model and industrial materials with different degrees of flexibility were studied. The first type of materials was a single phase model flexible aluminium titanate material (AT VF) developed for academic purposes by improving the grain growth. Its non-linear mechanical behaviour was obtained thanks to the thermal expansion mismatch of its grains according to the different crystallographic axis. The second one is multi-phased magnesia based industrial materials, whose flexibility is less accentuated, and for which the non-linear mechanical behaviour is obtained thanks to the thermal expansion coefficients mismatch between spinel aggregates and magnesia matrix. In order to apply the optical methods on these materials which exhibit lower strain-to-rupture, it was necessary to optimize the accuracy of these techniques by improving experimental conditions.In the case of AT VF, DIC and mark tracking method have been applied on four-points bending test at room temperature to underline the material asymmetric mechanical behaviour which induces a significant shift of the neutral fibre and to evaluate the relative displacement of rolls. The application of DIC has been extended to other experimental testing method such as Brazilian and Wedge Splitting test using the multi-phased magnesia based materials. This highlighted fracture mechanisms (crack occurrence and propagation) and the presence of crack branching phenomenon promoted thanks to an initial micro-cracks network voluntary introduced by thermal expansion mismatch between the different phases so as to improve their thermal shock resistance. From displacement experimentally obtained by DIC, a finite element method updating (FEMU-U) has been developed to determine material properties.

More and more pressure is exerted on railway infrastructure due to an increasing transportation demand and population density. Instead of expanding the net, a possible solution could lie in the enlargement of the capacity by operating longer trains rather than more short ones. However, close attention has to be paid to the behaviour and the lifetime of the infrastructure under these changed loads. In special bridges are delicate aspects in this matter. In the current thesis the simply supported Banafjäl bridge located on the Bothnia Line in the North of Sweden is studied more in detail with regards to this aspect. It is a high-speed composite railway bridge with a span of 42 m. A detailed 3D finite element (FE) model is made available. However in order to make reliable predictions about the behaviour under increasing train length loads, it had to be further improved. Different methods of calibrating measured response data to an existing FE model, finite element model updating (FEMU), are available and a detailed overview is given at the beginning of this thesis. Next a sensitivity analysis was performed to select the material parameters which are most influential for the result and will be updated. In the following, FEMU is carried out by means of two iterative updating methods, genetic and gradient-based optimization, after which also a combination of these two is implemented. Two objective functions are chosen and it is shown that all methods converge to a global optimal solution. After adjusting the initial model with the updated parameter values, a fatigue analysis on this updated model is carried out for high-speed trains of multiple lengthsby means of the Palmgren-Miner rule. The fatigue is found to increase with increasing train length and in particular when the speed approaches resonance speed. By extension an operating chart is created to indicate the maximum amount of train passages per day in function of speed and train length for a type 4 fatigue train. Furthermore, damping has been shown to have a positive effect on the fatigue, the larger this effect for shorter trains. The static behaviour has been proven not to be a problem and so will solely the weight of trains induce little to no fatigue problems in this particular bridge.

No description available.

Structural Health Monitoring (SHM) is a promising tool for condition assessment of bridge structures. SHM of bridges can be performed for different purposes in long or short-term. A few aspects of short- and long-term monitoring of highway bridges are addressed in this research. Without quantifying environmental effects, applying vibration-based damage detection techniques may result in false damage identification. As part of a long-term monitoring project, the effect of temperature on vibrational characteristics of two continuously monitored bridges are studied. Natural frequencies of the structures are identified from ambient vibration data using the Natural Excitation Technique (NExT) along with the Eigen System Realization (ERA) algorithm. Variability of identified natural frequencies is investigated based on statistical properties of identified frequencies. Different statistical models are tested and the most accurate model is selected to remove the effect of temperature from the identified frequencies. After removing temperature effects, different damage cases are simulated on calibrated finite-element models. Comparing the effect of simulated damages on natural frequencies showed what levels of damage could be detected with this method. Evaluating traffic loads can be helpful to different areas including bridge design and assessment, pavement design and maintenance, fatigue analysis, economic studies and enforcement of legal weight limits. In this study, feasibility of using a single-span bridge as a weigh-in-motion tool to quantify the gross vehicle weights (GVW) of trucks is studied. As part of a short-term monitoring project, this bridge was subjected to four sets of high speed, live-load tests. Measured strain data are used to implement bridge weigh-in-motion (B-WIM) algorithms and calculate the corresponding velocities and GVWs. A comparison is made between calculated and static weights, and furthermore, between supposed speeds and estimated speeds of the trucks. Vibration-based techniques that use finite-element (FE) model updating for SHM of bridges are common for infrastructure applications. This study presents the application of both static and dynamic-based FE model updating of a full scale bridge. Both dynamic and live-load testing were conducted on this bridge and vibration, strain, and deflections were measured at different locations. A FE model is calibrated using different error functions. This model could capture both global and local response of the structure and the performance of the updated model is validated with part of the collected measurements that were not included in the calibration process.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20760号 / 工博第4412号 / 新制||工||1686(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 杉浦 邦征, 教授 白土 博通, 教授 清野 純史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM