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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.
391

Analyse thermomécanique d'un réducteur épicycloïdal : Application aéronautique / Thermo mechanical analysis of an epicyclic gear train : Aeronautical application

Durand de Gevigney, Jérôme 18 December 2013 (has links)
Dans le contexte environnemental actuel, l’amélioration des performances énergétiques des transmissions mécaniques par engrenage est un réel challenge. De part, leur compacité et leur arrangement axisymétrique, les transmissions mécaniques de type réducteur à trains épicycloïdaux sont de plus en plus répandues dans divers applications (éolien, aéronautique,…). Il est généralement admis que les principales sources de dissipation de puissance dans de telles transmissions sont dues au frottement aux dentures, au mode de lubrification (barbotage ou injection de lubrifiant), au piégeage d’huile entre les dents lors de l’engrènement et à la ventilation des mobiles. Il est également à noter que les pertes de puissance générées par une transmission ne peuvent être découplées de son comportement thermique. En effet, les échauffements locaux dans la transmission ont un impact sur les propriétés du lubrifiant, qui ont elles-mêmes une influence sur les pertes de puissance. A partir de ce postulat, le travail présenté dans ce manuscrit propose un modèle numérique permettant de quantifier les différents postes de pertes de puissance générées dans un réducteur épicycloïdal, lubrifié par injection d’huile, pour une application aéronautique. / In the current environmental context, gearbox efficiency has become a major issue. Because of their compactness and axi-symmetric arrangement, planetary gearboxes are widely used in several applications (such as wind, aerospace…). It is generally accepted that total power losses in such gear transmissions can be decomposed into the contributions of the friction between teeth, the lubrication process (oil splash or jet), the oil trapping during meshing and tooth windage. It is noticed that power losses produced by a mechanical transmission cannot be dissociated from its thermal behavior. Indeed, the local warmings impact lubricant physical properties and these last have influence on power losses in return. Based on this postulate, the purpose of this work is to develop a numerical model in order to estimate the power losses generated into a jet lubricated planetary gear train, for an aeronautical application.
392

Raupenfahrzeug-Dynamik

Graneß, Henry 18 April 2018 (has links) (PDF)
Bei Raupenfahrwerken wird das allgemeingültige Prinzip verfolgt, dass durch die scharnierbare Aneinanderreihung von Kettengliedern eine fahrzeugeigene Fahrstrecke entsteht. Dies erlaubt selbst schwere Geräte im unwegsamen, brüchigen Gelände mit großen Vortriebskräften zu mobilisieren. Jedoch wohnt, der Diskretisierung des Raupenbandes in Glieder endlicher Länge geschuldet, dem Fahrwerk eine hohe Fahrunruhe inne. Dadurch entstehen zeitvariante Lasten im Fahrwerk, welche die Lebensdauer der Kette, des Fahrwerkantriebs und der Tragstruktur des Fahrzeugs limitieren und somit regelmäßig kostenintensive Instandsetzungsmaßnahmen erzwingen. Diese Problemstellung aufgreifend beschäftigt sich die Arbeit mit der Analyse und Optimierung des fahrdynamischen Verhaltens von Raupenfahrzeugen. Zugleich werden Methoden vorgestellt, welche eine rechenzeiteffiziente Simulation von Raupenfahrzeugen und Antriebssystemen zulassen.
393

Ce qu'un corps peut devenir : cartographie entre danse et philosophie / What a Body can Become : cartography between Dance and Philosophy

Potrovic, Laura 27 September 2017 (has links)
Cette thèse n'explore pas ce qu'est le corps, mais ce qu'un corps peut devenir. Elle explore le corps comme un événement en train de se faire à travers les concepts tels que le Corps sans Organes (Antonin Artaud, Gilles Deleuze et Félix Guattari), le bodying (Erin Manning), le corps en train de se faire (Erin Manning) et le devenir (Gilles Deleuze et Félix Guattari). Ce que tous ces concepts ont en commun est l'état de devenir. Ici, le corps devient, et en tant que tel - c'est un verbe, une activité, une force. Cette thèse explore non seulement le corps comme une force de devenir, mais elle explore également le devenir de cette force - au niveau moléculaire, expérientiel et relationnel. Comme le dit Manning, un corps est toujours plus qu'un corps. Ici, nous essayons d'aborder les devenirs physiques, expérientiels et relationnels d'un corps en mouvement. Ce qui bouge le corps de l'état d'être vers l'état de devenir est le mouvement. Cette thèse tente de montrer comment le mouvement ne s'arrête jamais. Nous bougeons toujours, donc, il y a une continuité de devenir. Un corps n'est jamais uniquement une forme, il est une force-forme. Le mouvement est celui qui ouvre le corps vers son devenir de force(s). Un corps en mouvement n'est pas une forme d'expression, mais une force d'expressivité. Le mouvement fait le corps, par conséquent, le corps lui-même est un mouvement. Nous ne dansons pas avec le corps, nous dansons le corps lui-même. Le corps est une partition, un corps-partition, de son devenir. / This thesis does not explore what body is, but what a body can become. It explores the body as event-in-making throughout the concepts such as Body without Organs (Antonin Artaud, Gilles Deleuze and Félix Guattari), bodying (Erin Manning), body-in-making (Erin Manning). What all of those concepts have in common is the same state - a state of becoming. Here, body becomes, and as such - it is a verb, an activity, a force. This thesis does not only explore the body as a force of becoming, but it also explores the becoming of that force - at the molecular, experiential and relational level. As Manning says, a body is always more-than one. Here, we are trying to approach the physical, experiential and relational becomings of a body in movement. That which moves the body from the state of being into the state of becoming is movement. This thesis is trying to show how movement never stops. We always move, therefore, there is a continuity of becoming. A body is never just a form, but a force-form. Movement is that which opens the body toward its becoming of force(s). A moving body is not a form of expression, but a force-field of expressivity. Movement makes the body, therefore, the body itself is a movement. We are not dancing with the body, we are dancing the body itself. The body is a score, a body-score, of its own becoming.
394

Prefabricerade betongbroar över järnväg - En jämförelse mellan traditionell platsgjuten konstruktion och prefab på plats / Prefabricated concrete bridges over railway - A comparison between traditional cast on site construction and precast on site

Eriksson, Andreas, Larsson, Nils January 2016 (has links)
När nya betongbroar över järnväg ska upprättas finns det många aspekter som försvårar byggandet, som t.ex. att trafiken inte kan stoppas helt förutom under kortare perioder under byggtiden. Tågstoppen planeras in många år i förväg vilket gör att produktionen måste planeras och utföras utefter de planerade stoppen. Det är svårt att få till en industrialiserad brobyggnadsprocess med högre effektivitet och mer upprepning. Den traditionella platsgjutna metoden är den metod som är vanligast i Sverige trots att det finns metoder som skulle kunna ersätta den. Det huvudsakliga syftet med rapporten är att ta reda på om prefabricerade betongelement på plats är en möjlig metod för att underlätta byggandet av nya betongbroar över järnväg. Denna rapport baseras på en fallstudie av ett befintligt broprojekt för att se vilka fördelar och förbättringar metoden med prefab på plats kan ge i olika aspekter. Utöver detta har intervjuer och en enkätundersökning genomförts för att samla in material och åsikter om prefab och industrialiserade brobyggnadsprocesser. Resultatet i denna rapport visar att metoden med prefab på plats är mer fördelaktig än den traditionella platsgjutna metoden i flera hänseenden. Det är en metod som gör det möjligt att nå upprepning och serietillverkning av broar. Vid intervjuerna framkom att entreprenörerna är intresserade av prefablösningar men bland annat krav på utformning och konservativ syn på prefab från beställarna hindrar möjligheterna för att tillämpa metoden / When new concrete bridges over railway is to be established there are many aspects that complicates the construction, such as that traffic not can be stopped completely except for short periods during the construction process. The train stop is planned many years in advance, which means that construction must be planned and performed along the planned stops. It is difficult to get to an industrial bridge construction process with higher efficiency and more repetition. The traditional cast on site method is the most common in Sweden although there are methods that could replace it. The main purpose of the report is to find out if precast concrete elements on site is a possible method to facilitate the construction of new concrete bridges over the railway. This report is based on a case study of an existing bridge project to see the benefits and improvements the method with precast on site can provide in various aspects. Also interviews and surveys was conducted to collect opinions about prefabrication and industrial bridge construction. The results in this report show that the method of prefab on site is more advantageous than the traditional cast on site method in several respects. It is a method that makes it possible to reach repetition and serial production of bridges. The interviews revealed that contractors are interested in prefabricated solutions, but among other requirements for the design and conservative view of prefabrication from clients prevents the possibility of applying the method.
395

Modélisation du comportement d'un remblai en sol renforcé sous chargement ferroviaire de type TGV / Numerical model of a mechanically stabilized earth wall under high speed train loading

Payeur, Jean-Baptiste 16 October 2015 (has links)
Cette thèse étudie le comportement de remblais en sol renforcé lors du passage de trains par simulation numérique. Il s'agit de déterminer si les trains à grande vitesse ont un impact particulier sur ce type d'ouvrage. Après un état de l'art des remblais en sol renforcé et de la modélisation numérique de problèmes ferroviaires, les résultats du chargement harmonique d'un remblai expérimental en Terre Armée sont analysés. Ils montrent que les valeurs des tractions dans les armatures, des contraintes et déplacements dans le massif dépendent de la fréquence de la sollicitation, c'est-à-dire de la vitesse de passage du train. On construit un modèle 3D aux éléments finis pour reproduire cette expérience. Il permet de retrouver les valeurs expérimentales avec une bonne précision, en mettant en avant l'importance du choix des lois de comportement du sol, du parement et des armatures. Ce modèle avec ses paramètres est alors utilisé pour discuter du comportement local de l'interface armature/remblai au cours d'un chargement harmonique en régime établi. Le confinement varie beaucoup le long des armatures supérieures au cours du chargement dynamique, tandis que les tractions sont peu affectées par le chargement dynamique. Cependant, malgré ces variations au cours du temps, la stabilité de l'interface reste peu affectée par rapport au cas d'un chargement statique. Un second modèle a été développé pour représenter un remblai de taille plus importante, en utilisant la modélisation multiphasique et en utilisant un repère mobile pour prendre en compte le déplacement du train. Les aspects théoriques et l'implémentation de ce modèle dans le code CESAR-LCPC sont détaillés. On l'utilise pour effectuer une étude tri-dimensionnelle d'un remblai renforcé. Elle met en évidence la faible influence de la vitesse de la charge sur la réponse de l'ouvrage, dans le cas d'un remblai rigide ayant des caractéristiques tirées du remblai expérimental. Dans le cas d'un remblai moins rigide, la vitesse d'un TGV peut s'approcher de la vitesse des ondes de cisaillement dans le massif avec des conséquences significatives au sein de la structure. Finalement, les valeurs expérimentales et les deux modèles numériques développés présentent les mêmes tendances : l'effet dynamique du passage du train a pour conséquence une augmentation des déplacements et une variation du confinement des armatures, tandis que les niveaux de traction sont peu affectés par la charge, ce qui nous incite à conclure que la vitesse du train n'est pas significativement pénalisante sur la stabilité des remblais pour les paramètres issus de l'analyse du remblai expérimental. Toutefois, ces résultats dépendent fortement de la géométrie de la structure, de la façon de modéliser le train, des lois de comportement et des valeurs des paramètres retenus pour le sol, le parement et l'interface sol/armature / This study focuses on the numerical modeling of the Mechanically Stabilized Earth (MSE) walls behavior under High Speed Train (HST) loading. First, the state of the art in reinforced earth as well as in railway dynamics modeling is analyzed. Then we present results coming from the testing of a one-scale reinforced embankment submitted to harmonic loading. They indicate that tensile forces in reinforcements, stresses and displacements depend on loading frequency which is related to train speed. One proposes a 3D Finite Element Model (FEM) in order to numerically reproduce this experimentation. The numerical results fit reasonably well with the experimental ones, highlighting the great importance of the choice of the constitutive law for the soil, reinforcement and facing. The same model is used to locally investigate the soil/reinforcement interface behaviour during a harmonic loading in steady-state. The confining pressure presents significant variations along the reinforcement strip during the dynamic loading while tensile forces are less affected by the load. Nevertheless, the global interface stability remains acceptable compared to a static load. A second numerical model is proposed, which represents a bigger embankment. The multiphase model is used to represent the reinforced soil and moving coordinates are used to take into account the moving train. Theoretical developments of this model and its implementation into CESAR-LCPC FEM code are detailed. The results indicate that the train speed does not play a big role in the overall response of the structure, in the case of a stiff reinforcement comparable to the experimental one. If the embankment is weaker, the HST speed may be close to shear waves speed within the soil, which has significant consequences into the structure, particularly on the stability of the soil/reinforcement interface. Globally the experimental results and those coming from both numerical models present the same trends: the dynamic effect coming from the train passing leads to the in-crease of displacements and confining pressure close to the highest strips, while tensile forces are less affected by the load. This leads us to the conclusion that the train speed does not have a significant effect on the stability of MSE walls, at least for embankments having similar parameters than the experimental one. However these results strongly depend on the embankment geometry, the way to model the train and the parameters and constitutive laws chosen for the soil, the soil/reinforcement interface and the facing
396

Coherent Control and Reconstruction of Free-Electron Quantum States in Ultrafast Electron Microscopy

Priebe, Katharina Elisabeth 19 December 2017 (has links)
No description available.
397

Data mining of temporal sequences for the prediction of infrequent failure events : application on floating train data for predictive maintenance / Fouille de séquences temporelles pour la maintenance prédictive : application aux données de véhicules traceurs ferroviaires

Sammouri, Wissam 20 June 2014 (has links)
De nos jours, afin de répondre aux exigences économiques et sociales, les systèmes de transport ferroviaire ont la nécessité d'être exploités avec un haut niveau de sécurité et de fiabilité. On constate notamment un besoin croissant en termes d'outils de surveillance et d'aide à la maintenance de manière à anticiper les défaillances des composants du matériel roulant ferroviaire. Pour mettre au point de tels outils, les trains commerciaux sont équipés de capteurs intelligents envoyant des informations en temps réel sur l'état de divers sous-systèmes. Ces informations se présentent sous la forme de longues séquences temporelles constituées d'une succession d'événements. Le développement d'outils d'analyse automatique de ces séquences permettra d'identifier des associations significatives entre événements dans un but de prédiction d'événement signant l'apparition de défaillance grave. Cette thèse aborde la problématique de la fouille de séquences temporelles pour la prédiction d'événements rares et s'inscrit dans un contexte global de développement d'outils d'aide à la décision. Nous visons à étudier et développer diverses méthodes pour découvrir les règles d'association entre événements d'une part et à construire des modèles de classification d'autre part. Ces règles et/ou ces classifieurs peuvent ensuite être exploités pour analyser en ligne un flux d'événements entrants dans le but de prédire l'apparition d'événements cibles correspondant à des défaillances. Deux méthodologies sont considérées dans ce travail de thèse: La première est basée sur la recherche des règles d'association, qui est une approche temporelle et une approche à base de reconnaissance de formes. Les principaux défis auxquels est confronté ce travail sont principalement liés à la rareté des événements cibles à prédire, la redondance importante de certains événements et à la présence très fréquente de "bursts". Les résultats obtenus sur des données réelles recueillies par des capteurs embarqués sur une flotte de trains commerciaux permettent de mettre en évidence l'efficacité des approches proposées / In order to meet the mounting social and economic demands, railway operators and manufacturers are striving for a longer availability and a better reliability of railway transportation systems. Commercial trains are being equipped with state-of-the-art onboard intelligent sensors monitoring various subsystems all over the train. These sensors provide real-time flow of data, called floating train data, consisting of georeferenced events, along with their spatial and temporal coordinates. Once ordered with respect to time, these events can be considered as long temporal sequences which can be mined for possible relationships. This has created a neccessity for sequential data mining techniques in order to derive meaningful associations rules or classification models from these data. Once discovered, these rules and models can then be used to perform an on-line analysis of the incoming event stream in order to predict the occurrence of target events, i.e, severe failures that require immediate corrective maintenance actions. The work in this thesis tackles the above mentioned data mining task. We aim to investigate and develop various methodologies to discover association rules and classification models which can help predict rare tilt and traction failures in sequences using past events that are less critical. The investigated techniques constitute two major axes: Association analysis, which is temporal and Classification techniques, which is not temporal. The main challenges confronting the data mining task and increasing its complexity are mainly the rarity of the target events to be predicted in addition to the heavy redundancy of some events and the frequent occurrence of data bursts. The results obtained on real datasets collected from a fleet of trains allows to highlight the effectiveness of the approaches and methodologies used
398

Rozvoj tramvajových tratí na Ostravsku / Development of the tram network in Ostrava region

Bartoňová, Andrea January 2013 (has links)
This diploma thesis is focused on the public transport. The theoretical part contains short characteristics of the transport infrastructure followed by a description of the logistics processes in public transport. The practical part focused on the transport network in the city of Ostrava aims at the public transport in the city, particularly public transport system and integrated transport system. The goal of thesis is to give the readers a comprehensive look at the public transport in Ostrava and to present the tramtrain system.
399

Modeling Mild Thermal Cracking of Heavy Crude Oil and Bitumen with VLE Calculations

Guerra, André 20 August 2018 (has links)
The current shortage of crude oil from conventional sources has increased interest in developing unconventional resources such as oil sands. Heavy crudes and bitumen are found in Northern Alberta and their exploration, processing, and transport to market pose challenges in the use of these resources. Part of the solution to these challenges involves the reactive thermal processing of heavy crudes and bitumen. This thesis focused on mild thermal cracking reactions, and two studies regarding these reactions were presented. The first was an experimental study performed in a pilot-scale semi-batch reactor. The three crude oils were heated to 350, 400, 425, and 450°C at 1240 kPa. A five-lump reaction model combined with a process simulator with VLE calculations was fitted with the experimental data obtained. The goodness of fit between the model predicted values and experimental values for the Hardisty (MBL), Albian Heavy Synthetic (AHS), and Christina Lake Dilute Bitumen (CDB) were determined to be 0.99, 0.99, and 0.98, respectively. Moreover, 80, 85, and 89% of the optimized model’s predicted values had less than 10% error for MBL, AHS, and CDB, respectively. The second study described the implementation of a mild thermal cracking reaction model to the development of a train car fire-model for the assessment of safety aspects in the design of train cars used to transport crude oil. Case studies were conducted using the UniSim® depressuring utility and a previously developed mild thermal cracking reaction model to demonstrate the effect of compositional change. Three crude oils with varying properties and representative of the types of crudes transported by rail in Canada were used here: MBL, AHS, and CDB. The case studies conducted showed the performance of a train car fire-model to be dependent on the crude oil characteristics: up to -57% and -99% difference in model predicted variables for AHS and CDB, respectively, when compared to MBL. Furthermore, the model’s performance was also shown to be affected by the compositional change of a given crude oil due to mild thermal cracking reactions: up to 42% difference in model predicted variables when compared to the base case.
400

Nos trilhos da morte : tragédia ferroviária, debate judicial e racismo em Sergipe nos anos 40 / In the trail of death : railway tragedy, judicial debate and racism in Sergipe in the 40s

Bezerra, Luiz Paulo Santos 24 August 2017 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In 1946, between the municipalities of Riachuelo and Laranjeiras, in Sergipe, more precisely at kilometer 458 of BR 101, a serious train accident occurs, which enters to history as the largest rail disaster in Brazil. In it, known by the victims as "the suburban train", several people of different occupations (merchant, marketer, mason, fisherman among others) and from several regions of the interior of Sergipe traveled for commercial purposes. Dozens of dead and several injured were found at the site of the disaster, and survivors reported the incident in a criminal case of approximately 400 pages. The study we intend to present in this work becomes important, as there are still no historical reports of researchers who analyzed the biggest railway disaster in Brazil. This makes our work an unpublished research, having as a parameter the lack of complete materials at the national and regional / local level, leaving us incomplete references. Our main objective, therefore, is to reconstitute a judicial system that involved the appalling accident. We will try to analyze and pursue all the characters who were involved directly and indirectly in the episode. We will try to give visibility to forgotten subjects, the racial theories that surrounded the period, the memories and everyday scenes of a post-war Sergipe. We used for the writing, judicial sources, as the crime process to which all the plot is passed and from where we found the characters that will be mentioned while the chapters. The newspapers will become a very precious source, because we will know if the news of the disaster has touched Brazil and the world. As a strong mean of communication, newspaper reports will give us, to a certain extent, a glimpse of how the stories were spread and how journalistic circles saw the tragedy. The memories and chronicles, not least important, will contribute as a revealing material of the daily and scenario that we are analyzing. Finally, I add the Vox populi, the Cordel of Rodolfo Coelho Cavalcante from Alagoas, who portrayed the tragedy in verse and prose. The method we used for the cataloging of data was the same revealed by Carlo Ginzburg in several of his works, the indicial paradigm, in view of our search for clues that reveal the concrete guilt of the tragedy and the complex ideological reality of the 1930s and 1940, in which solidified racial ideas were circulating in the world and in Brazil. / Em 1946, entre os municípios de Riachuelo e Laranjeiras, em Sergipe, mais precisamente no quilômetro 458 da BR 101, ocorre um grave acidente de trem, que entra para a história como o maior desastre ferroviário do Brasil. Nele, conhecido pelas vítimas como “o trem suburbano”, várias pessoas de diferentes ocupações (comerciante, feirante, pedreiro, pescador entre outras) e de várias regiões do interior sergipano viajavam para fins comerciais. Dezenas de mortos e vários feridos foram encontrados no local do desastre, e os sobreviventes relataram o acontecimento num processo-crime de aproximadamente 400 laudas. O estudo que pretendemos apresentar neste trabalho torna-se importante, pois ainda não existem relatos históricos de pesquisadores que analisaram o desastre ferroviário. O que transforma o nosso trabalho numa pesquisa inédita, tendo como parâmetro a inexistência de materiais completos no âmbito nacional e regional/local, restando-nos referências incompletas. O nosso principal objetivo, portanto, permeia reconstituir uma trama judiciária que envolveu o pavoroso acidente. Buscaremos analisar e perseguir todos os personagens que estavam envolvidos direta e indiretamente no episódio. Tentaremos dar visibilidade a sujeitos esquecidos, as teorias raciais que cercaram o período, a memórias e cenas cotidianas de um Sergipe pós-guerra. Utilizamos para a escrita, fontes judiciárias, como o processo crime ao qual se passa toda a trama e de onde retiramos os personagens que serão citados no decorrer dos capítulos. Já os jornais se tornarão uma fonte muito preciosa, pois saberemos se a notícia do desastre percorreu o Brasil e o mundo. Como forte meio de comunicação, as notas de jornais nos dará, até certa medida, uma visão de como as matérias foram divulgadas e de que forma os círculos jornalísticos vislumbraram a tragédia. As memórias e crônicas, não muito menos importante, contribuirão como um material revelador do cotidiano e cenário ao qual estamos analisando. Acrescento por fim, a vox populi, o cordel do alagoano Rodolfo Coelho Cavalcante que retratou a tragédia em verso e prosa. O método que utilizamos para a catalogação dos dados foi o mesmo revelado por Carlo Ginzburg em diversas de suas obras, o paradigma indiciário1, tendo em vista a nossa busca por pistas que revelem a culpabilidade concreta da tragédia e da realidade ideológica complexa das décadas de 1930 e 1940, em que ideias raciais solidificadas estavam em circulação no mundo e no Brasil. / São Cristóvão, SE

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