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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.
71

Mise au point et exploitation d'une nouvelle technique pour la reconnaisance des sols : le PANDA 3 / Development and interpretation of new technique for soils characterization : the panda 3

Escobar Valencia, Esteban Julio 07 May 2015 (has links)
Ce travail présente les développements récents réalisés sur le pénétromètre PANDA 3. Il s'agit d'un pénétromètre dynamique instrumenté qui permet à partir de la mesure puis du découplage des ondes créées par l’impact sur l’appareil, d’obtenir pour chaque coup une courbe charge-enfoncement σp-sp du sol ausculté. L’exploitation de cette courbe permet de déterminer des paramètres de résistance (résistance de pointe qd), de déformation (module dynamique Ed P3), des caractéristiques d’amortissement Js et de célérité d'ondes (CsP3 et CpP3) des sols auscultés en fonction de la profondeur tout au long du sondage. Cependant, et bien que la méthode soit très intéressante, celle-ci est restée au stade d’un prototype de laboratoire. Il est donc nécessaire de réaliser une étude plus approfondie sur l'essai lui-même et sur l’information contenue dans la courbe σp-sp en vue de fiabiliser la mesure et d’améliorer son exploitation. Dans un premier temps, nous présentons un bref aperçu sur les techniques de reconnaissance géotechnique et plus particulièrement celle des essais de pénétration dynamique. Le principe général du PANDA 3 est également présenté. La deuxième partie est consacrée au développement d'un nouveau prototype de pénétromètre PANDA 3. Ce développement s’appuie sur plusieurs études visant à valider la qualité des informations recueillies, leur bonne reproductibilité et le traitement des signaux d’acquisition. De même, un modèle numérique discret du battage pénétrométrique développé à l’aide du logiciel Particle Flow Code (Itasca) est présenté permettant de valider la technique de mesure. La troisième partie traite d'une étude comparative des résultats obtenus avec le PANDA 3 et d’autres techniques d'auscultation in situ afin de valider les résultats obtenus et l’utilisation de l’appareil dans des conditions réelles. Par ailleurs l’extension de cette technique de mesure au cas des pénétromètres lourds est appliquée dans le but de mesurer l'énergie transmise et d’étalonner le système de battage. Enfin, la dernière partie est consacrée à l'interprétation et l'exploitation des signaux en pointe afin d'affiner le modèle d'interprétation de la courbe charge-enfoncement. L'analyse de l'ensemble des signaux enregistrés au laboratoire a permis d’approcher une méthodologie d'exploitation de la courbe. L'application de la méthode proposée a été réalisée pour différents sols aussi bien au laboratoire que sur le terrain. Les résultats obtenus ont été confrontés avec d'autres types d’essais. / This work presents the recent developments made on the penetrometer PANDA®3. The instrumented dynamic penetrometer allowing, from the measurement and the decoupling of waves created by the impact, to obtain the load-penetration curve σp-sp of the soil. The exploitation of this curve allows determining the failure parameter (tip resistance qd), deformation (dynamic modulus EdP3), damping characteristics (Js) and wave speed (CsP3 and CpP3) of the investigated soil according to depth all along the sounding. However, although the proposed method is very interesting, it has remained at the stage of a laboratory prototype. It is therefore necessary to conduct a more thorough study of the test itself and the information provided from the σp-sp curve in order to obtain reliable measurement and improve their exploitation. First of all, we are presenting a brief overview of the geotechnical in-situ testing particularly that of the dynamic penetration tests as well as the general principle of PANDA 3 is presented. The second part is devoted to the development of a new prototype of the PANDA 3 penetrometer. This development is based on several studies aiming at validating the quality of the information, good reproducibility and treatment of the acquisition signals. Similarly, a discrete numerical model of the penetrometer developed using the Particle Flow Code software (Itasca) is presented to validate the measurement technique. The third part deals with a comparative study of the results obtained with the PANDA 3 and other in situ investigation techniques to validate the obtained results and the use of the device in real conditions. Moreover, the extension of this measurement technique in the case of heavy penetrometer is applied in order to measure the transmitted energy and to calibrate the driving system. The last part is devoted to refining the interpretation and exploitation of the load-penetration curve. The analysis of all the signals recorded in the laboratory allowed to approach a methodology of curve exploitation. The application of the proposed method was carried out for different soils both in the laboratory and on field. The results were confronted with other types of tests.
72

Dynamická analýza mostních konstrukcí / Dynamic analysis of bridges structures

Prokš, Tomáš January 2017 (has links)
The diploma thesis deals with dynamic analysis of cable-stayed steel pedestrian footbridge. The dynamic response of pedestrian-induced vibration was studied. The response of structure exeeded standard acceptance limit. Due to the effect of installed Tuned Mass Damper was studied. Motion equations of single and two degree of freedom model were solved in program MATLAB and the results were compared with numeric model in ANSYS.
73

Dynamische Lastbalancierung und Modellkopplung zur hochskalierbaren Simulation von Wolkenprozessen

Lieber, Matthias 03 September 2012 (has links)
Die komplexen Interaktionen von Aerosolen, Wolken und Niederschlag werden in aktuellen Vorhersagemodellen nur ungenügend dargestellt. Simulationen mit spektraler Beschreibung von Wolkenprozessen können zu verbesserten Vorhersagen beitragen, sind jedoch weitaus rechenintensiver. Die Beschleunigung dieser Simulationen erfordert eine hochparallele Ausführung. In dieser Arbeit wird ein Konzept zur Kopplung spektraler Wolkenmikrophysikmodelle mit atmosphärischen Modellen entwickelt, das eine effiziente Nutzung der heute verfügbaren Parallelität der Größenordnung von 100.000 Prozessorkernen ermöglicht. Aufgrund des stark variierenden Rechenaufwands ist dafür eine hochskalierbare dynamische Lastbalancierung des Wolkenmikrophysikmodells unumgänglich. Dies wird durch ein hierarchisches Partitionierungsverfahren erreicht, das auf raumfüllenden Kurven basiert. Darüber hinaus wird eine hochskalierbare Verknüpfung von dynamischer Lastbalancierung und Modellkopplung durch ein effizientes Verfahren für die regelmäßige Bestimmung der Überschneidungen zwischen unterschiedlichen Partitionierungen ermöglicht. Durch die effiziente Nutzung von Hochleistungsrechnern ermöglichen die Ergebnisse der Arbeit die Anwendung spektraler Wolkenmikrophysikmodelle zur Simulation realistischer Szenarien auf hochaufgelösten Gittern. / Current forecast models insufficiently represent the complex interactions of aerosols, clouds and precipitation. Simulations with spectral description of cloud processes allow more detailed forecasts. However, they are much more computationally expensive. Reducing the runtime of such simulations requires a highly parallel execution. This thesis presents a concept for coupling spectral cloud microphysics models with atmospheric models that allows for efficient utilization of today\'s available parallelism in the order of 100.000 processor cores. Due to the strong workload variations, highly scalable dynamic load balancing of the cloud microphysics model is essential in order to reach this goal. This is achieved through a hierarchical partitioning method based on space-filling curves. Furthermore, a highly scalable connection of dynamic load balancing and model coupling is facilitated by an efficient method to regularly determine the intersections between different partitionings. The results of this thesis enable the application of spectral cloud microphysics models for the simulation of realistic scenarios with high resolution grids by efficient use of high performance computers.
74

Méthodologie de contrôle en place des micropieux à partir d'essais dynamiques / In situ control methodology for micropiles based on dynamic load testing

Calvente, René Matias 30 June 2014 (has links)
L’état de l’art réalisé dans le cadre de ce travail a permis d’identifier une grande variété de techniques de réalisation de micropieux avec des comportements effort-déformation difficiles à prédire. Quant aux méthodes de contrôle, du point de vue de l’intégrité il existe deux méthodes développées pour les pieux lesquelles ne sont pas toujours applicables aux cas de micropieux ; et du point de vue du contrôle du comportement mécanique, il existe un essai assez utilisé pour le contrôle de micropieux : l’essai d’arrachement. Cet essai est facile à réaliser et à interpréter, cependant il est onéreux (long temps d’essai) et difficile à mettre en place. Un autre type d’essai, utilisé dans le contrôle de fondations profondes, est l’essai de chargement dynamique. La recherche bibliographique a permis d’identifier les avantages et inconvénients de ce type d’essai adaptés et déjà validés dans le contrôle de pieux. Nous avons donc proposé une nouvelle méthodologie basée sur des essais de chargement dynamique à faible contrainte nécessitant des énergies de battage beaucoup moins importantes que dans les essais de chargement dynamique classiques. Le protocole et dispositif d’essai de la méthodologie ont été calibrés et validés à partir de simulations numériques afin notamment de justifier les choix de l’énergie d’impact, de la masse du marteau et de l’amortisseur à utiliser. Les observations numériques sont ensuite vérifiées expérimentalement sur des micropieux à échelle réelle mis en place dans un site expérimental développé dans le cadre de ce projet. La méthodologie de contrôle en place de la résistance en service de micropieux développée, c’est une méthode originale simple à réaliser, facile à mettre en oeuvre et d’interprétation immédiate. Elle a été validée aussi dans le cas de micropieux à échelle réelle en conditions maitrisées dans le site expérimental et non maitrisées dans trois chantiers réels de micropieux. Finalement, le progrès dans les recherches, a permis le développement d’une méthodologie de contrôle de la résistance limite de micropieux. Pour cela nous proposons d’utiliser un modèle analytique de prédiction du comportement effort-déformation alimenté par les résultats de l’essai de chargement dynamique à faible déformation et d’un essai complémentaire de reconnaissance des paramètres à la rupture du sol. L´objectif de ce développement est de proposer une prédiction de la résistance limite du micropieux testé sans compromettre son intégrité. L’application de la méthodologie a montré qu’elle donne des résultats très proches de ceux observés dans les essais statiques. / The review of the state-of-the-art of micropiles produced as part of this work allows to identify a wide variety of construction methodologies which have a stress-strain behavior difficult to predict. As for the testing methods, there are methods for assessing the condition of piles or shafts but they are not always applicable to the micropiles; and in terms of the control of mechanical behavior, the most used load testing micropile is the uplift static load test. The static load test is easy to perform and interpret, however the reaction system is cumbersome and slow to erect, therefore this test is time and cost consuming. Another type of test that can be used in the control of deep foundations is the dynamic load testing. The literature review helped to identify the advantages and disadvantages of this type of test that has been adapted and validated in control of pile behavior. The new methodology proposed in this work is based on low-strain dynamic test requiring a smaller impact energy than a high-strain dynamic test. The testing protocol and loading device of the methodology have been calibrated and validated by numerical simulations in order to justify the choice of the impact energy, the weight of hammer and the cushion that will be used. The numerical observations are then verified by experiences in full-scale micropiles installed in an experimental site developed as part of this project. The developed in situ control methodology of the resistance in service of micropiles is an original method, easy to carry out, simple to execute and with an immediate interpretation. This methodology has been validated on full-scale micropiles in contained conditions and also in uncontained conditions in three real projects of micropiles. Finally, the advances in the investigations have led to develop a methodology for control the micropile’s ultimate resistance. We propose to use an analytical model for predicting the stress-strain behavior, which must be supplied with the results of the low-strain dynamic micropile test and of a complementary geotechnical test in order to examine the parameter of soil failure. The goal of this development is to provide a method for predict the micropile’s ultimate resistance without compromising its integrity. The results of the application of the new method to the experimental micropiles are in close agreement with the results observed in the static load test. / La revisión del estado del arte en relación a micropilotes, realizada en este trabajo, ha permitido identificar una gran variedad de técnicas de construcción, donde la predicción de sus comportamientos mecánicos, es una tarea difícil de realizar. Con respecto a los métodos de control, desde el punto de vista de la integridad, existen actualmente métodos no siempre aplicables a los micropilotes, y desde el punto de vista del control del comportamiento mecánico, el ensayo más utilizado es el ensayo de arrancamiento. El ensayo de arrancamiento es de fácil realización e interpretación, sin embargo es oneroso, por su larga duración y la necesidad de disponer de equipos muy pesados.Otro tipo de ensayo, que es utilizado para el control de fundaciones profundas en general, es el ensayo de carga dinámica, cuyas ventajas y desventajas han sido identificadas en la investigación bibliográfica.La nueva metodología propuesta, motivo de este trabajo, está basada en los ensayos de carga dinámica a baja deformación, donde se necesita una energía de impacto mucho menos importante que en el caso de los ensayos clásicos de carga dinámica.El protocolo de la metodología y su dispositivo de ensayo han sido calibrados y validados a partir de simulaciones numéricas con el fin de, principalmente, justificar la elección de la energía de impacto, de la masa del martillo y del amortiguador a utilizar. Las observaciones numéricas han sido, luego, verificadas experimentalmente sobre micropilotes a escala real, instalados en un sitio experimental desarrollado en el marco de este proyecto.La metodología de control in situ, de la resistencia en servicio de micropilotes, desarrollada en este trabajo, es un método original, simple de realizar, con un sistema fácil de instalar y de interpretación inmediata. Ella ha sido validada, en el caso de micropilotes a escala real en condiciones controladas en el sitio experimental, y no controladas en el caso de tres proyectos reales.Además, el avance en las investigaciones, dio lugar al desarrollo de una metodología de control de la resistencia límite de micropilotes. Para ello proponemos utilizar un modelo analítico de predicción del comportamiento esfuerzo-deformación alimentado por resultados del ensayo de carga dinámica a baja deformación y de un ensayo complementario de reconocimiento de los parámetros de ruptura del suelo. El objetivo de este desarrollo es de proponer un método de predicción de la resistencia límite de micropilotes sin comprometer su integridad. La aplicación de la metodología ha mostrado que los resultados son muy cercanos a los observados en los ensayos de carga estática.
75

Técnicas de proteção e restauração em redes ópticas elásticas / Protection and restoration techniques in elastic optical networks

Lourenço, André Luiz Ferraz 26 November 2015 (has links)
As redes ópticas estão passando por mudanças significativas, impulsionadas pelo crescimento exponencial do tráfego, principalmente advindo de serviços multimídia e armazenamento em nuvem. Esta demanda exigirá aumento da capacidade da taxa de transmissão para padrões como 400 Gb/s e 1 Tb/s. Nesse contexto, foi proposta uma arquitetura de rede com grade de frequências granular flexível chamada elastic optical network (EON). A EON divide o espectro de frequências em fatias (slots) de tamanho fixo e aloca grupos de slots contíguos estritamente de acordo com os requisitos de banda das demandas de conexão, implicando eficiência de uso do espectro. Com o aumento significativo da taxa de transmissão, acentuou-se a preocupação em manter a sobrevivência da rede, já que pouco tempo de queda no serviço pode acarretar uma imensa perda de dados. Neste trabalho, investigamos esquemas de proteção baseados em caminhos compartilhados (shared-path protection, SPP) e esquemas de restauração de tráfego. Avaliamos esquemas divulgados na literatura como o dynamic load balancing shared-path protection (DLBSPP) e esquemas de restauração como o traffic aware restoration (TAR) e bandwidth squeezed restoration (BSR). Avaliamos também uma heurística de alocação de slots chamada inverted dual stack (IDS). O DLBSPP utiliza balanceamento dinâmico de carga para computar os caminhos primários e de proteção compartilhados. O TAR executa a restauração dinâmica ordenando as conexões por granularidade de banda. O BSR utiliza a capacidade de contração de banda do EON para restaurar conexões por meio da política de melhor esforço ou de banda garantida, dependendo do acordo de níveis de serviço do cliente. O esquema IDS concentra o maior número possível de slots compartilhados em uma região do espectro. As medidas de desempenho dos algoritmos são avaliadas segundo as métricas: probabilidade de bloqueio, taxa de utilização do espectro, número médio de hops e taxa de restauração falha. As simulações computacionais mostram o bom desempenho da utilização do esquema IDS com DLBSPP. / Optical networks are undergoing significant changes driven by the exponentially growing traffic, especially coming from multimedia and cloud storage services. This demand will require increasing of the transmission rate capacity as high as 400 Gb/s and 1 Tb/s. Within this context, it was proposed the elastic optical network (EON), which is a network architecture with flexible granular frequency grid. EON divides the frequency spectrum into slices (slots) of fixed size and allocates groups of contiguous slots strictly according to the bandwidth requirement of the connection demands, providing high spectrum use efficiency. The significant increase in transmission rate put emphasis on the need to maintain the survival of the network, since the occurrence of faults in the network nodes or links can cause huge loss of data. In this work, we investigate protection schemes based on shared-path protection (SPP) and traffic restoration schemes. We evaluate schemes related in the literature, such as the dynamic load balancing shared-path protection (DLBSPP), and restoration schemes such as the traffic aware restoration (TAR) and the bandwidth squeezed restoration (BSR). The DLBP scheme uses dynamic load balancing to compute primary and shared protection paths. The TAR performs dynamic restoration ordering the connections based on band granularity. The BSR uses EON\'s band squeezing feature to restore connections by means of the best effort or guaranteed bandwidth strategy, depending on the customer\'s service level agreement. IDS scheme concentrates the maximum possible number of shared slots in a given region of the spectrum. Performance of the algorithms are evaluated according to metrics: blocking probability, spectrum utilization rate, average number of hops and failure restoration rate. Computer simulations show that the use of the IDS scheme improves the performance of the investigated algorithms.
76

Técnicas de proteção e restauração em redes ópticas elásticas / Protection and restoration techniques in elastic optical networks

André Luiz Ferraz Lourenço 26 November 2015 (has links)
As redes ópticas estão passando por mudanças significativas, impulsionadas pelo crescimento exponencial do tráfego, principalmente advindo de serviços multimídia e armazenamento em nuvem. Esta demanda exigirá aumento da capacidade da taxa de transmissão para padrões como 400 Gb/s e 1 Tb/s. Nesse contexto, foi proposta uma arquitetura de rede com grade de frequências granular flexível chamada elastic optical network (EON). A EON divide o espectro de frequências em fatias (slots) de tamanho fixo e aloca grupos de slots contíguos estritamente de acordo com os requisitos de banda das demandas de conexão, implicando eficiência de uso do espectro. Com o aumento significativo da taxa de transmissão, acentuou-se a preocupação em manter a sobrevivência da rede, já que pouco tempo de queda no serviço pode acarretar uma imensa perda de dados. Neste trabalho, investigamos esquemas de proteção baseados em caminhos compartilhados (shared-path protection, SPP) e esquemas de restauração de tráfego. Avaliamos esquemas divulgados na literatura como o dynamic load balancing shared-path protection (DLBSPP) e esquemas de restauração como o traffic aware restoration (TAR) e bandwidth squeezed restoration (BSR). Avaliamos também uma heurística de alocação de slots chamada inverted dual stack (IDS). O DLBSPP utiliza balanceamento dinâmico de carga para computar os caminhos primários e de proteção compartilhados. O TAR executa a restauração dinâmica ordenando as conexões por granularidade de banda. O BSR utiliza a capacidade de contração de banda do EON para restaurar conexões por meio da política de melhor esforço ou de banda garantida, dependendo do acordo de níveis de serviço do cliente. O esquema IDS concentra o maior número possível de slots compartilhados em uma região do espectro. As medidas de desempenho dos algoritmos são avaliadas segundo as métricas: probabilidade de bloqueio, taxa de utilização do espectro, número médio de hops e taxa de restauração falha. As simulações computacionais mostram o bom desempenho da utilização do esquema IDS com DLBSPP. / Optical networks are undergoing significant changes driven by the exponentially growing traffic, especially coming from multimedia and cloud storage services. This demand will require increasing of the transmission rate capacity as high as 400 Gb/s and 1 Tb/s. Within this context, it was proposed the elastic optical network (EON), which is a network architecture with flexible granular frequency grid. EON divides the frequency spectrum into slices (slots) of fixed size and allocates groups of contiguous slots strictly according to the bandwidth requirement of the connection demands, providing high spectrum use efficiency. The significant increase in transmission rate put emphasis on the need to maintain the survival of the network, since the occurrence of faults in the network nodes or links can cause huge loss of data. In this work, we investigate protection schemes based on shared-path protection (SPP) and traffic restoration schemes. We evaluate schemes related in the literature, such as the dynamic load balancing shared-path protection (DLBSPP), and restoration schemes such as the traffic aware restoration (TAR) and the bandwidth squeezed restoration (BSR). The DLBP scheme uses dynamic load balancing to compute primary and shared protection paths. The TAR performs dynamic restoration ordering the connections based on band granularity. The BSR uses EON\'s band squeezing feature to restore connections by means of the best effort or guaranteed bandwidth strategy, depending on the customer\'s service level agreement. IDS scheme concentrates the maximum possible number of shared slots in a given region of the spectrum. Performance of the algorithms are evaluated according to metrics: blocking probability, spectrum utilization rate, average number of hops and failure restoration rate. Computer simulations show that the use of the IDS scheme improves the performance of the investigated algorithms.
77

Lávka pro pěší přes lagunu / Pedestrian bridge across the lagoon

Bezručová, Kristína January 2018 (has links)
The aim of this thesis is the design and analysis of pedestrian bridge across the lagoon. Three variants were designed. The variant of structure, which combines stress ribbon with steel arches, was chosen for analysis. There is a chapter in this thesis which deals with an ideal shape of arches for different types of loads. The calculation of load effects was made in software Ansys 17.0, considering scnstruction stages. Ultimate limit state and state limit state are evaluated. For evaluation of concrete cross sections was used MS Excel. Steel cross sections were evaluated in software Ansys 17.0. d Dynamic behaviour of construction was assessed. The mode shapes and natural frequencies were calculated. The harmonic excitation response was studied. The loss of stability was checked. The design and assessment are according to the european standards.
78

Konstrukční návrh uložení měřící aparatury IMC ve vozidle / Design of Data Acquisition Equipment IMC Fastening System in the Car

Černý, Martin January 2018 (has links)
Devices for measuring the dynamic load and vibration of certain parts of the bodywork or parts of other parts of the vehicle are made using accelerometers and measuring instruments IMC. It must be simply installed into the interior of the vehicle so that it is not necessary to remove any parts of the interior and to avoid damage to all parts of the interior. The preparation must also withstand the considerable dynamic load generated by the harder operation tests.
79

Statická a dynamická analýza předpjaté mostní konstrukce / Static and dynamic analysis of Prestressed bridge structure

Hokeš, Filip January 2014 (has links)
The main objective of the thesis is to perform static and dynamic analysis of prestressed concrete bridge structures in computational system ANSYS. For the analysis was chosen footbridge over the river Svratka in Brno. In relation to this topic are solved various types of modeling prestress at a finite element level. Before analyzing the footbridge is analyzed in detail the static system and the corresponding final geometry of the structure. Knowledge of the functioning of the static system is used to build the computational model of the structure, on which is subsequently performed static and dynamic analysis.

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