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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.
31

Contrôle et diagnostic par un réseau de capteurs magnétiques en automobile / Diagnostics and monitoring in automobile using a magnetometer network

Le Goff, Alexis 02 February 2011 (has links)
Cette thèse présente les différentes sources de champ magnétique dans un véhicule automobile à moteur thermique. Le but de ce travail est d'exploiter la mesure du champ magnétique dans une automobile afin d'extraire des données utiles pour caractériser le fonctionnement ou le dysfonctionnement des éléments du véhicule. Les expérimentations que nous avons conduites nous ont permis de mesurer, identifier, caractériser et modéliser les différentes sources de champ magnétique en automobile. Les circuits électriques, l'alternateur électrique, mais également le déplacement des pièces ferromagnétiques engendrent des champs d'induction. Toutes ces sources se mélangent sur le réseau de capteurs magnétiques installé dans le véhicule. Nous avons mis en œuvre des algorithmes de séparation de sources et de soustraction de bruit permettant de récupérer les signaux utiles pour la surveillance. L'analyse vibratoire déjà utilisée pour le diagnostic des automobiles permet d'étudier les accélérations et chocs des éléments à surveiller. L'analyse magnétique que nous présentons ici permet d'étudier d'autres caractéristiques comme le déplacement de ces pièces ou les courants électriques présents dans le système. Nous montrons que les mesures magnétiques, sont un nouvel outil de diagnostic qui peut être utilisé pour le contrôle automobile, en complément de l'analyse vibratoire. Diverses applications industrielles potentielles utilisant des capteurs à bas coût, sur le contrôle des roues, du moteur et des feux électriques sont développées. Enfin, nous ouvrons une réflexion sur la généralisation de ces résultats aux véhicules électriques en présentant les problématiques et les besoins spécifiques en particulier dans l'étude du comportement magnétique des accumulateurs électriques utilisés pour stocker l'énergie. / In this thesis the various sources of magnetic field in an automobile with heat engine are presented. The aim of this work is to make use of the measures on the magnetic field in an automobile in order to extract useful information for monitoring or diagnosis of the vehicle. The experiments we made led us to measure, to identify, to characterize and to model the various sources of magnetic field in an automobile. The electric circuits, the electric generator, and also the displacements of ferromagnetic pieces can create magnetic field. All those sources are mixed on the sensor network. We have developed source separation algorithms and noise removing techniques, in order to get useful signals. Vibration analysis has already been used for diagnosis in automobile and allows to study the accelerations and shocks of the elements to monitor. The magnetic analysis allows to study other parameters such as pieces displacements or the electric currents in the system. We show that magnetic analysis is a new diagnosis tool that could be used as additional information. Several concrete potential applications on wheel and engine monitoring, and electric bulb diagnosis are presented. Finally, we give an angle of reflection about generalizing those results to electric vehicles by presenting the specific problems and needs for those vehicles. In particular, the study of the magnetic behavior of the electric Lithium batteries is presented.
32

Propagation de délaminage par fatigue vibratoire dans un matériau composite / Delamination propagation in composite material under vibratory fatigue

Maillet, Irène 08 April 2013 (has links)
Dans le domaine aéronautique les structures sont soumises à de la fatigue sonique due aux phénomènes aéro-acoustiques. Le dimensionnement statique actuel des avions composites couvre les cas de charge en fatigue. Mais avec le besoin de toujours plus réduire la masse de l’avion et l’augmentation des connaissances dans le comportement matériau, les marges statiques vont être réduites dans un futur proche et la propagation par fatigue deviendra un enjeu majeur. Il sera donc nécessaire d’évaluer la possibilité de propagation d’un délaminage dû à une erreur de fabrication ou un impact dans une structure composite. Dans ce contexte, une méthode a été proposée pour étudier la propagation de délaminage sous chargement vibratoire. Tout d’abord, des essais de caractérisation de la propagation de délaminage sous chargement vibratoire ont été mis en place et validés pour les deux principaux modes de rupture. Les effets induits par la fréquence élevée de sollicitation, auto-échauffement induit et vitesse de chargement élevée, ont été pris en compte dans la mise au point et le traitement de ces essais. Ensuite, des outils numériques ont été développés pour permettre la simulation d’une structure délaminée sous chargement vibratoire et l’étude de la propagation du délaminage. A l’aide des approches expérimentales et numériques mises en place et des données matériau identifiées, l’analyse a pu être conduite sur un cas réel de structure aéronautique. Un essai de fatigue vibratoire sur une structure de reprise de plis a ainsi été réalisé. L’évolution du délaminage pendant l’essai est représenté de façon satisfaisante par le modèle numérique. / Because of their lightness, stress adaptive design and strong stiffness, composite materials are more and more used in aeronautics. Aeronautical structures are submitted to vibrations during their service life due to aerodynamic turbulent flow around the structure. The current static design of composite aircraft covers fatigue loading cases. But with the need to more and more lighten the structure, and the knowledge increase in material behavior, the static reserve factors will be reduced in the near future and sonic fatigue will become a major issue. It will be necessary to evaluate the possibility of a delamination propagation in a composite structure due to a manufacturing error or to an impact. In this context, a method has been proposed to study the propagation of a delamination under vibratory loading. Firstly, tests to characterize the propagation of delamination under vibration loading have been developed and validated for the two main failure modes. The effects induced by the highfrequency loading, self-heat generation and high speed loading, were considered in the elaboration of these tests and in the data reduction. Then, numerical tools have been developed to allow the simulation of a delaminated structure under vibratory loading in order to study the delamination propagation. Using experimental and numerical approaches and the material data identified, the analysis could be conducted on a real case of aircraft structure. A vibration fatigue test on a ply-drop structure has been achieved. The evolution of delamination during the test is adequately modelized by the numerical model.
33

Estudo do alívio das tensões residuais, em peça estampada, pela técnica de vibrações mecânicas /

Santos, Carlos Henrique dos. January 2011 (has links)
Orientador: Ângelo Caporalli Filho / Banca: Valdir Alves Guimarães / Banca: Wyser José Yamakami / Resumo: A estampagem de chapas metálicas é importante e se destaca entre os processos de conformação, pois, é possível de se obter vários produtos com alta produtividade e baixo custo. No entanto, como todo processo de conformação pode haver alguns inconvenientes, como as tensões residuais, que são geradas devido ao aumento da resistência mecânica do material resultante da deformação plástica a frio ou devido à geometria complexa da peça, com regiões de tração e compressão. Algumas medidas são realizadas dentro da área fabril para minimizar o problema e assim as peças irem para a etapa seguinte de conformação. Uma delas é a realização de tratamento térmico de alívio das tensões residuais de forma manual. O problema é que esse processo não garante nenhum controle da microestrutura e também não há garantia que as tensões foram aliviadas e como consequência peças são sucateadas na etapa seguinte de conformação, acarretando um aumento maior dos custos de fabricação. Neste trabalho foi realizado um estudo do alívio das tensões residuais através de vibrações mecânicas abaixo da frequência de ressonância em uma peça estampada a frio. O objetivo deste trabalho é avaliar os efeitos das vibrações mecânicas abaixo da frequência de ressonância no alívio das tensões residuais, de tal forma que possa ser uma opção ao tratamento térmico. Os resultados mostram que ouve redução nas tensões residuais, porém novos estudos devem ser realizados para garantir a eficácia deste processo / Abstract: The stamping of sheet metal is important and stands out among the forming processes, therefore it is possible to obtain various products with high productivity and low cost, however, the whole process of conformation can bring some drawbacks, such as residual stresses, that are generated due the rigidity of the material against cold plastic deformation or due the geometry complex of the piece, with areas on tension and compression. Some processes are carried out within the factory area to minimize the problem and so the pieces go to the next step of forming, for instance perform heat treatment relief residual stresses. The problem is that this process does not guarantee any control of the microstructure and also there is not guarantee that the tensions were reduced and failure pieces in the next step of conformation, resulting in a greater increase in manufacturing costs. In this paper has been studied relief residual stress by mechanical vibrations, with carry out of treatment relief from vibrations below the resonant frequency in component cold drawned. The objective of this study is to evaluate the effects of mechanical vibration below the resonant frequency to relieve residual stresses, so that might be an option to heat treatment. The results show a reduction in residual stress; however, we have to compare them with other treatments for which they can ensure the effectiveness of mechanical vibrations / Mestre
34

Projeto de um mini-moinho vibratório auxiliado por técnicas de metodologia de projeto / Project of a vibratory mini-mill aided by techniques of project methodology

Roni Cesar de Carvalho 04 May 2007 (has links)
Concepção, desenvolvimento de projeto e fabricação de um mini-moinho vibratório para cerâmica avançada. Diversas áreas de engenharia são hoje dependentes de componentes de cerâmica avançada. A conformação da cerâmica, baseada na compactação de pós, seguida de sinterização, tem encontrado diversas aplicações em processos de manufatura dos produtos cerâmicos avançados. Tamanhos de partículas pequenas (abaixo de 1 \'mü\'m) e controle da distribuição granulométrica são desejáveis, porque aumentam a reatividade das partículas cerâmicas. O presente projeto busca pela concepção de um moinho que processe pequena quantidade de material em múltipla moagem no atendimento das necessidades de ambientes de trabalho de desenvolvimento e fabricação de peças especiais tais como os laboratórios e indústrias de pequeno porte. Normalmente os moinhos encontrados no mercado são para escalas maiores e moagem simples. Dessa forma, baseado em técnicas de metodologia de projeto, principalmente na busca de soluções para a concepção e desenvolvimento, tanto do sistema \"moinho vibratório\", quanto dos jarros, procurou-se desenvolver um procedimento para um projeto adaptativo de moinho vibratório. Foi projetado e construído um moinho para moagem simultânea de seis jarros com volume útil de moagem de 20 a 300 mL em cada jarro. Foram realizadas moagens de alumina de tamanho médio inicial de 5,2 \'mü\'m as quais foram analisadas em sedígrafo. Foram obtidos pós com 0,7 \'mü\'m de diâmetro médio equivalente e pós com 18% abaixo de 0,2 \'mü\'m. / Conception, project development and manufacture of a vibratory mini-mill for advanced ceramics. Diverse areas of engineering today are dependent on advanced ceramic components. The ceramic conformation, based on powder compaction, and followed by sintering, has been found to have many different applications in manufacturing process in advanced ceramic products. Small size particles (below 1 \'mü\'m) and the control of particle size distribution are desirable, as they increase the reactivity of ceramic particles. The present project involves a search for the conception of a mill that process small amounts of material in multiple milling to meet the requirements of research laboratories and small industries. Normally the mills available on the market are for larger scale and simple, milling. Therefore based on techniques of project methodology, mainly in brainstorming for conception and development, not only on the \"vibratory mill system\" but also on the jars, it was developed a procedure for an adaptable project for a vibratory mill. A mill for the simultaneous milling of six jars with milling volume from 20 to 300 mL on each jar was projected and built. Alumina with medium particle size of 5.2 \'mü\'m, were milled using the \"vibratory mill system\" and analyzed by sedigraph. After milling the particles had an average diameter of 0.7 \'mü\'m with 18% of the particles below 0.2 \'mü\'m.
35

Analýza vibračního válce s novým typem kinematiky řízení / Analysis of vibratory roller with new type of steering kinematics

Votroubek, Jan January 2011 (has links)
Diploma thesis includes design of bearings of steering joints of tandem vibratory pivot-steering roller Ammann AV 95-2, design of bearings of steering joints of tandem vibratory with new type of steering kinematics and calculation and comparison of contact pressures between drum and soil for different angles of turn of front and rear drum for different types of tandem vibratory rollers. Comparison of contact pressures is realised for pivot steering roller AV 95-2, articulated tandem roller AV 80 X, articulated tandem roller with modified configuration of steering-joints and tandem roller with new type of steering kinematics.
36

Návrh zásobníku s posuvem a orientací gumové ucpávky / Suggestion of case feeder for orientation gum plug

Laurenc, Filip January 2012 (has links)
The main target of this diploma thesis was to make suggestion orientation and movement product, this solution describe, make calculation and draw drawings documentation.
37

Ground Vibrations due to Vibratory Sheet Pile Driving

Lidén, Märta January 2012 (has links)
Vibratory driving is today the most common installation method of sheet piles. The knowledge of the induced ground vibrations is however still deficient. This makes predictions of the vibration magnitudes difficult to carry out with good reliability. To avoid exceeding the limit values, resulting in stops of production, or that vibratory driven sheet piles are discarded for more costly solutions, a need for increased knowledge of the vibration process is imminent. With increased knowledge, a more reliable and practical prediction model can be developed.  The aim of this thesis is to analyze measured data from a field study to increase the understanding of the induced vibrations and their propagation through the soil. The field study was performed in Karlstad in May 2010, where a trial sheet piling prior to an extension of Karlstad Theatre was carried out. During the trial sheet piling, two triaxial geophones were mounted at the ground surface at two different distances from the sheet piles, to measure the vibration amplitude. The field test is associated with some limitations. Only four sheet piles were driven, with one measurement per sheet pile. Some measurements were less successful and some parameters had to be assumed. This limits the accuracy but still provides some interesting results. Another aim is to compare the measured values to existing models for predicting vibrations from piling and sheet piling operations. There are today several prediction models available, which however often provide too crude estimations or alternatively are too advanced to be incorporated in practical use. Two basic empirical prediction models are compared to the measured values in Karlstad, where the first is one of the earliest and most well known models and the other is a later development of the first model. The purpose of this comparison is to evaluate these models to contribute to the development of a new prediction model. The results show that the earlier model greatly overestimates the vibration magnitude while the later developed model provides a better estimation.  A literature study is performed to gain a theoretical background to the problem of ground vibrations and how they are related to the method of vibratory driving of sheet piles. The analysis considering the field study and prediction models is mainly performed by using MATLAB to obtain different graphical presentations of the vibration signals. The conclusions that can be drawn from the results are that the focus of vibration analysis should not always be the vertical vibration components. Horizontal movements of the sheet pile might be introduced, e.g. by the configuration of the clamping device, which generates additional vibrations in horizontal directions. The soil characteristics influence the magnitude of the vibrations. As the sheet pile reaches a stiffer soil layer, the vibration magnitude increases. A realistic and reliable prediction model should take the characteristics of the soil into account.
38

Inteligentní řídící metody v automatizaci procesů řízení stavebních strojů / Intelligent Control Methods in Automation of Process of Construction Machines Control

Vaverka, Michal January 2010 (has links)
This work deals with the possibility of use of intelligent methods in construction machines control. These methods are based on GPS in combination with using laser and ultrasonic technology. There is in detail described especially control by robotic total station and 3D control, which includes digital model of construction site. The new trends of control are especially applied on the vibratory rollers. There are taken into consideration: achievement of sufficient degree of compaction on the basis of on-line information about conditions of subsoil.
39

ADAPTIVE SLIDING MODE CONTROL WITH APPLICATION TO A MEMS VIBRATORY GYROSCOPE

Fei, Juntao January 2007 (has links)
No description available.
40

Attitude Reference Devices for Gun-Launched Rocket Vehicles

Hill, William Barry 10 1900 (has links)
<p> A proposal is made to extend the present capabilities of gun-launched rocket vehicles to include attitude control during flight. The problems involved are stated and design criteria for possible sensors are listed. A review of presently available sensing devices is made and rejection of unsuitable instruments is based on fundamentals of their design and operation. </p> <p> A report is made upon the sensors which most adequately fulfil the harsh environmental requirements of gun-launch. These sensors are infrared-horizon sensors and a tuning fork vibratory gyroscope. A preliminary design is given for the tuning fork gyroscope a well as a summary of fundamental design considerations. </p> / Thesis / Master of Engineering (ME)

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