Acionamentos elétricos em corrente contínua ainda são largamente empregados em plantas industriais. Os modelos usualmente adotados para os motores envolvem diversas simplificações, desprezando os efeitos da reação de armadura. Neste trabalho, foi realizada uma pesquisa bibliográfica a fim de se encontrar modelos matemáticos que contemplassem os efeitos da reação de armadura em máquinas CC. Devido à escassez de material encontrado, optou-se por desenvolver um modelo próprio com base em dados obtidos experimentalmente em ensaios de laboratório. Tal modelo, o qual foi validado através da comparação com os dados experimentais, visa a contemplação dos principais efeitos da reação de armadura tanto no circuito de campo como também no circuito de armadura. / DC motor drives are still extensively used in industrial plants. The motor models usually adopted involve several simplifications, neglecting armature reaction effects. In this work, an extensive bibliographical survey was carried on so that references of mathematical models that account for the armature reaction effects on DC machines could be found. The lack published material on the subject led us to undertake laboratory experiments on a DC machine in order to evaluate the effects of the armature current on the field circuit and on the armature circuit as well. Finally, a mathematical model was derived and validated by the comparison of simulated results with real data.

A multi-layered analysis on the morphological development of Ephesus in relation to the Temple of Artemis and an investigative wandering through the streets of this city in the era of Roman Empire highlights this thesis characterized by a consistent search for the significance of the notion of urban armature. From the standpoint of those who lived at that time, special attention is directed toward the colonnaded avenues as well as to their formal and social impacts within the city fabric. The thesis re-reads Ephesus within two main parts / first the urban form in relation to the topographical provision and sacred landscape provided by the site itself / and then from the ground level through a walking trip of the city as it appeared in the second century A.D. Crucial to this visual experience is the semantic quality of the environment at a collective level since the meaning of the experience would be useless without considering the meaning of signs and symbols within the environment. Thus, bounding ancient society and urban space at the phenomenological level, the small trip starts at the harbor and concludes at the Temple of Artemis, the irrefutable symbol of Ephesus and the most revered shrine in Asia Minor.

The objective of this work has been to investigate the applicability of the gas gun to study the armature-rail interface wear characteristics relevant to rail gun operations. The approach involved developing constitutive models for armature materials (aluminum 6061) as well as oxygen-free high-thermal conductivity copper as the rail material. Taylor rod-on-anvil impact experiments were performed to validate the accuracy of constitutive strength models by correlating predictions of dynamic simulations in ANSYS AUTODYN with experimental observations. An optical comparator was used to discretize the cross sectional deformation profile of each rod-shaped sample. Parameters of the Johnson-Cook strength model were adjusted for each material to match deformation profiles obtained from simulations with profiles obtained from impact experiments. The fitted Johnson-Cook model parameters for each material were able to give overall deformed length and diameter values within 2% of the experimentally observed data. Additional simulations were then used with the validated strength model parameters to design the geometry involving cylindrical rods of armature material accelerated through a concentric cylindrical extrusion die made of copper, to emulate the interface wear effects produced in a rail gun operation. Experiments were conducted using this geometry and employing both the 7.62mm and 80mm diameter gas guns. Microstructural analysis was conducted on interfaces of the recovered samples from both designs. Hardness measurements were also performed along the interface layer to evaluate the structure formation due to solid-state wear or melt formation. The stress and strain conditions resulting in the observed microstructural effects were correlated with predictions from numerical simulations performed using the validated material models. The overall results illustrate that the stress-strain conditions produced during acceleration of Al through hollow concentric copper extrusion die, result in interface deformation and wear characteristics that are influenced by velocity. At velocities (less than 800m/s), interface wear leads to formation of layer dominated by solid-state alloying of Cu and Al, while higher velocities produce a melted and re-solidified aluminum layer. Hence, use of different armature (Al-based) and rail (Cu-based) materials can be evaluated with the gas-gun set-up employed in the current work to study the effects of interface wear ranging from formation melt layer to solid-state alloying as a function of material properties and velocity.

Cette thèse de doctorat en géographie urbaine s'intéresse à l'évolution de l'armature urbaine depuis le début des années 1980 dans la province du Zhejiang en Chine. Les villes y ont connu de considérables changements: l'ampleur de l'urbanisation s'exprime tant dans leur évolution physique que dans leur distribution sur l'ensemble du territoire. Le Zhejiang, dont le taux d'urbanisation est passé de 13,7 à 61,6 % entre 1980 et 2010, est situé au sud de Shanghai. Il intègre une partie de la région du delta du Yangzi, l'un des bassins industriels et démographiques les plus dynamiques de Chine, et met en évidence les mutations urbaines aussi bien au sein de ce type de territoires riches et en plein essor que dans les terres en marge de leur développement. Le développement des petites villes, avec une population comprise entre 100 000 et 500 000 habitants, se révèle être le paramètre moteur de l'évolution de l'armature urbaine: alors que la province n'en compte que 13 en 1990, elles sont au nombre de 45 en 2000 puis 52 en 2010. En centrant la recherche sur ces entité : urbaines, l'étude analyse l'impact d'une politique de développement local standardisée, guidée par l'objectif prioritaire de croissance économique. À l'origine d'une promotion des petites villes au sein de la hiérarchie urbaine, ces pratiques uniformes provoquent de nombreuses fractures spatiales et socio-économiques et, en l'absence d'une planification régionale rigoureuse, n'anticipent pas une sélection urbaine déjà commencée. Les relations entre les villes et leurs périphéries rurales en sont modifiées, corollaire d'une redistribution des activités et des populations au sein d'un espace fonctionnel mixte. / This PhD in urban geography focuses on the evolution of the urban framework since the early 1980 : in the province of Zhejiang in China. The unprecedented size and rapidity of Chinese urbanization have transformed both their structure and territorial distribution. Zhejiang province, whose urbanization rate increased from 13.7 to 61.6% between 1980 and 2010, is located south of Shanghai. It covers a part of the Yangtzi Delta region, one of the biggest metropolitan areas in China, and highlights the urban transformations both within such thriving territories and in peripheral areas. The development of small cities, with a population between 100,000 and 500,000 inhabitants is proving to be the most common feature of the evolution of its urban framework: while the province had only 13 small cities in 1990, they were 45 in 2000 and 52 in 2010. Focusing on these urban entities, this research work analyses the impacts of a standardized urban planning, guided by the overriding objective of economic growth. Promoting small cities in the urban hierarchy, these planning practices nevertheless cause socio-spatial divisions. In addition, the absence of a rigorous regional planning does not anticipate an urban selection already started. The relations between urban cores and their rural peripheries are renewed, and lead to a redistribution of activities and populations in a mixed functional space. The chosen angle is to reveal the complex links between urban practices largely shared in China and socio-economic as well as space realities in order to outline the shape of the new urban framework. Small cities have new roles to play and support an on-going renewal of the urban hierarchy

Flyovers, or grade separated bridges or roads, are a type of urban infrastructure that has been used to facilitate high-speed vehicular movement. This once-popular strategy of the west, despite being considered as a failure for sustainable urban growth, has been adopted in Bangladesh to combat traffic congestion in Dhaka that has a crippling effect on daily life of the citizens. As was anticipated by many urban planners and architects, these expensive structures did little to reduce traffic congestion, but created additional problems of noise and air pollution as well as reduced pedestrian mobility. More importantly, these flyovers created wasted void spaces underneath that are uncomfortable, devoid of human scale and act as physical and visual barriers that cause tears on the urban fabric. The objective of this thesis is to explore how architecture can unlock the potential of the unused spaces under the flyovers in Dhaka, by turning these linear leftover spaces into dignified public places that improves the daily lived experiences of the urban dwellers, by minimizing the disruptions caused by the flyover and by realizing the potential inherent in the robust structure of the flyover. This thesis examines a democratized way of building, where the role of architecture is to facilitate organic and heterogeneous growth, addition and modification to the flyover in order to bring the human scale back to the massive flyover structure through a reconciliation of top-down and bottom-up approaches. The architectural interventions respond to the site conditions, potentials and demands. The architectural outcome is based on the concepts of creating a threshold, architecture as armature and parasitic structures. / Master of Architecture / Flyovers, or grade separated bridges or roads, are a type of urban infrastructure that has been used to facilitate high-speed vehicular movement. This once-popular strategy of the west, despite being considered as a failure for sustainable urban growth, has been adopted in Bangladesh to combat traffic congestion in Dhaka that has a crippling effect on daily life of the citizens. As was anticipated by many urban planners and architects, these expensive structures did little to reduce traffic congestion, but created additional problems of noise and air pollution as well as reduced pedestrian mobility. More importantly, these flyovers created wasted empty spaces underneath that are uncomfortable and act as physical and visual barriers that cause tears on the urban fabric. The objective of this thesis is to explore how architecture can unlock the potential of the unused spaces under the flyovers in Dhaka, by turning these linear leftover spaces into dignified public places that improves the daily lived experiences of the urban dwellers, by minimizing the disruptions caused by the flyover and by realizing the potential inherent in the robust structure of the flyover. This thesis examines a democratized way of building, where the role of architecture is to facilitate organic and de-centralized growth, addition and modification to the flyover in order to bring the human scale back to the massive flyover structure through a reconciliation of top-down and bottom-up approaches. The architectural interventions respond to the site conditions, potentials and demands. The architectural outcome is based on the concepts of creating a threshold, architecture as armature and parasitic structures.

A partir d'une base de données statistiques homogènes et de fonds cartographiques à différents niveaux spatiaux élaborés par nos critères, nous avons dressé un constat du fait urbain au Maghreb. La population urbaine progresse à un rythme soutenu mais donne lieu à une urbanisation qui est loin d'être un processus uniforme dans les territoires et entre les pays. La diversité des situations nationales, l'existence de traditions citadines... expliquent l'hétérogénéité des contextes urbains. L'explosion urbaine fulgurante que connaît l'ensemble du Maghreb est un phénomène récent mais dont le processus a démarré au début du 20ème siècle engendré par la colonisation et les mutations démographiques. Le système urbain des pays du Maghreb se modifie, les mutations sont particulièrement vigoureuses et elles affectent tous les échelons de la hiérarchie urbaine qui tend vers un équilibre. La volonté étatique de diffuser et d'harmoniser le fait urbain dans leur territoire s'est traduit par une stratégie reposant principalement sur les politiques économiques et administratives. Les littoraux concentrent toujours l'essentiel des villes, mais un début d'équilibrage des disparités régionales se met progressivement en place. Les dernières décennies ont vu exploser les tissus urbains et croître les populations urbaines, apparaître des métropoles, émerger des réseaux dynamiques de petites villes ce qui a profondément bouleversé l'armature urbaine de chaque pays. Cependant en près de 40 années, les pays du Maghreb ont construit et organisé des armatures urbaines répondant davantage à leurs objectifs.

Ce mémoire étudie, par la voie de la modélisation numérique, le comportement des murs en terre armée sous l'effet de la corrosion des armatures. L'analyse de données recueillies sur des ouvrages réels, âgés de plusieurs dizaines d'années, a montré la différence de comportement selon les types d'armatures, mais aussi la forte dispersion de l'ensemble des données. Elle a permis de proposer des relations entre la perte de masse et la diminution de la résistance et de l'allongement à la rupture des armatures.La présence des armatures très minces par rapport aux dimensions de l'ouvrage rend intéressante l'utilisation de méthodes d'homogénéisation. On a retenu une modélisation multiphasique, qui permet une modélisation satisfaisante de la traction dans les armatures.Quatre scénarios de corrosion ont été étudiés pour prendre en compte diverses situations susceptibles de conduire à des taux de corrosion élevés. La répartition spatiale de la corrosion peut avoir une influence importante sur le comportement du mur, sur le mécanisme de ruine et provoquer des phénomènes complexes de report des effort d'une armature sur une autre.Nous avons réalisé une étude paramétrique de l'effet de surcharges appliquées à l'ouvrage, et de certains détails de modélisation comme la jonction entre écailles, et la jonction entre armatures et écailles. Les résultats obtenus sont comparés à des mesures sur des ouvrages réels ou des modèles réduits, et à d'autres résultats de calcul.Les résultats conduisent à formuler des propositions concernant le suivi des déformations des ouvrages (nature et précision des mesures à effectuer, intervalles de temps entre inspections successives) / This thesis presents numerical simulations of the behavior of reinforced earth walls induced by the corrosion of the reinforcement strips. The preliminary analysis of a database, gathering results of laboratory tests, performed on soil and steel samples extracted from wall built several decades ago, has shown the difference in behavior between different types of reinforcement strips, and the large scattering of data. It served as a basis to derive relationships between weight loss, ultimate strength and ultimate strain of reinforcement strips.The presence of very thin strips compared to the size of the reinforced earth wall makes it interesting to use homogenization methods. We adopted a multiphase model, that makes it possible to get a satisfactory modeling of the tensile forces in reinforcement strips.We studied four corrosion scenarios to take into account various situations in which corrosion rates can become significant. The spatial distribution of corrosion can have a clear influence on the behavior of the wall, the failure mechanism, and create complex redistributions of tensile forces between adjacent strips. Parametric studies were carried out to investigate the effects of surcharges, and of some details of modeling, such as the junction between panels, or the junction between the reinforcement strips and the facing panels. Results have been compared with measures obtained on full scale reinforced earth walls or on physical models, and with results of other numerical simulations. Results provide elements for the definition of a strategy for the monitoring and the surveillance of reinforced earth walls

Dans beaucoup de pays du continent africain l'enclavement physique se pose encore aujourd'hui comme une contrainte majeure au développement. La région de Jijel après avoir longtemps joué un rôle de premier plan dans l'Algérie du Nord, se retrouve à un certain moment de l'histoire dans une situation d'isolement et de déclin par rapport à son environnement relativement dynamique. Est-ce un espace périphérique ? Ce n'est donc pas le cas, et ce n'est surement pas sa situation qui est mise en cause puisqu'elle fait partie de l'espace central de l'Algérie d'aujourd'hui. Mais l'opposition mer/montagne qui confère une singularité à ce territoire semble avoir donné l'avantage aux territoires voisins plus accessibles et propices au développement des communications ainsi que des échanges en tous genre. Les interventions des pouvoirs publics inscrites dans un contexte d'économie planifiée et dans une approche sectorielle, n'ont pas pris en charge l'ensemble de l'espace de la wilaya en se concentrant sur la zone de plaine côtière et en isolant davantage l'espace montagneux, déjà lésé, qui continu aujourd'hui de former une barrière qui bloque ce territoire par le sud. La dynamique animée par les acteurs locaux montre de son côté le chemin d'un développement en cohérence avec les potentialités et les aptitudes locales. Mais l'une comme l'autre initiative se trouvent confrontées à l'isolement de la région et doivent donc s'appuyer inévitablement sur l'ouverture de ce territoire sur le reste du pays. / In many countries of Africa, the geographical enclosing represents a major constraint for development. Although it played a foreground role in North Algeria for a long time, the Jijel area is nowadays found to be isolated and declining compared to its relatively dynamic environment. As it is clearly not a peripheral place, its location can't be blamed since it belongs to the center of Algeria today. However the sea/mountain opposition, which is singular on this territory, seems to have logically promoted more accessible territories with the development of communications as well as exchanges of all kind. In a context of planned economy and a sector-based approach, the authorities did not consider the whole wilaya place, focusing on the coastal plain zone, and isolating the already injured mountainous space that keeps on forming a barrier, blocking this territory by the south. On the other hand, the dynamics powered by the local actors show a way of a development in coherence with the local potentialities and aptitudes. However, each initiative is confronted with the enclosing of the area and will inevitably depend on the opening of this territory to the rest of the country. Its opening towards the South could also guarantee the opening to the North, and reconcile this place with the sea-side, so that it finds back its past role of “transit zone” between North and South Mediterranean.

L’objectif principal de cette thèse est d’étudier l’efficacité d’un inhibiteur à base de phosphate, Na3PO4, sur l’amorçage de la corrosion des armatures du béton. L’étude a été réalisée moyennant des méthodes électrochimiques et d’analyse de surface associées à l’émission acoustique et à la technique de la cellule de diffusion. L’évaluation de l’efficacité de l’inhibiteur en milieu simulant le béton a été réalisée en utilisant une nouvelle méthode de prétraitement de l’armature et de suivi de la corrosion. Il apparaît qu’en présence de Na3PO4 le rapport critique [Cl-] / [OH-] d’amorçage de la corrosion par piqûre atteint une valeur (R=15) nettement supérieure à celle sans utilisation de Na3PO4 (R ~ 0,6). L’inhibition est due à la formation d’un film renfermant des composés phosphatés (FePO4, (PO4)2Fe3,8H2O) qui bloque les sites anodiques actifs de l’acier, et augmente de façon significative sa résistance à la corrosion localisée. Pour un rapport R > 15, la dépassivation est liée à la présence d’une forte teneur en chlorure dans le milieu et conduit à terme, à la destruction quasi générale du film formé au préalable sur la surface de l’acier.La technique de cellule de diffusion a permis d’étudier, principalement, la cinétique de diffusion des ions Cl- dans un mortier confectionné sans et avec Na3PO4. La présence du phosphate dans le mortier entraîne une réduction du coefficient de diffusion des ions chlorures, et un accroissement important de la période d’amorçage du processus de corrosion. Enfin, l’inhibiteur adjuvant engendre la formation de nouveaux produits à base de phosphate dans le mortier (principalement : Ca3H2(P2O7)2, H2O et CaHPO4, 2H20). La disparition des hydrates usuels du ciment entraine une légère diminution de la résistance à la compression du béton, et de son module d’élasticité. Néanmoins, la présence de ces composés phosphatés bloque les pores du mortier et freine la diffusion des chlorures. Il s’ensuit une amélioration de la résistance de la corrosion du mortier armé en milieu 3 % NaCl. L’ensemble de ces résultats a montré clairement que cet adjuvant demeure recommandé pour la protection des armatures contre la corrosion en milieu chloruré. / The main aim of this thesis is to study the effectiveness of a phosphate based inhibitor, Na3PO4, against steel reinforcement corrosion initiation. The study was carried out by means of electrochemical methods and surface analysis associated with the acoustic emission and the diffusion cell technique. The effectiveness evaluation of this inhibitor in medium simulating the concrete pore solution has been studied using new method for reinforcement pretreatment and the corrosion monitoring. It appears that in the presence of Na3PO4, the critical ratio [Cl-] / [OH-] which prevents the pitting corrosion initiation reaches 15. This value is significantly higher than that found in the case of the steel without Na3PO4 (R ~ 0. 6). The inhibition is due to the layer formation containing phosphate compounds (FePO4, (PO4)2Fe3.8H2O), resulting in a considerable reduction of the anode active sites in contact with the electrolyte. This reinforces the steel passivation and greatly increases its resistance to localized corrosion. For R > 15 ratio, the depassivation has been associated with the presence of a high chloride content in the medium and with the destruction of the film formed beforehand on the steel surface. The diffusion cell technique was used to study mainly the Cl- ion diffusion kinetics in a mortar without and with Na3PO4. The presence of phosphate in the mortar, leads to the chloride ions diffusion coefficient reduction and an important increase of the corrosion process initiation period. Finally, the adjuvant inhibitor causes the formation of new phosphate-based products in the mortar (principally: Ca3H2(P2O7)2.H2O et CaHPO4.2H20). The disappearance of usual cement hydrates induces a slight decrease of compressive strength of the concrete and its elasticity modulus. Nevertheless, the presence of these phosphate compounds blocks the mortar pores and restricts the chloride diffusion. It follows an improvement of the corrosion resistance of the reinforced mortar in 3% NaCl medium. All these results clearly show that this adjuvant is recommended for the reinforcement protection against corrosion in chloride medium.

La corrosion dans le béton précontraint est considérée parmi les pathologies les plus dangereuses dans le secteur du génie civil. En effet ce phénomène se caractérise par la gravité de ses conséquences économiques et sécuritaires. L’objectif de ce travail consiste à évaluer l’efficacité d’un inhibiteur à base de phosphates Na3PO4.12H2O contre la corrosion des aciers de précontrainte. L’étude a été d’abord menée en milieu synthétique simulant le béton chloruré sur des armatures tendues à 80% Rm, puis d’une part sur des éprouvettes en mortier précontraint conçues à l’échelle laboratoire, et d’autre part en utilisant la technique de cellule de diffusion pour tester l’efficacité de l’inhibiteur à long terme. Les résultats issus de l’étude réalisée dans le milieu simulant ont révélé que la présence des phosphates entraine l’augmentation du seuil critique d’amorçage de corrosion localisée R=[Cl-]/[OH-] jusqu’à la valeur de 5 au lieu de 0,4. Ceci semble être dû à deux actions inhibitrices des phosphates à savoir : la stabilisation de la couche protectrice à base d’oxyde de fer et la formation de composés phosphatés très peu solubles qui bloquent les sites anodiques actifs, augmentant ainsi la résistance de l’acier à la corrosion localisée. L’emploi de Na3PO4.12H2O en tant qu’adjuvant diminue légèrement la résistance à la compression du mortier. Cependant les composés phosphatés provenant de la réaction de l’inhibiteur avec les hydrates de ciment colmatent les pores du mortier et freinent la diffusion des chlorures. Ceci améliore le comportement à la corrosion des armatures enrobées de mortier précontraint. Enfin, lorsque le triphosphate de sodium est utilisé comme inhibiteur migrateur ou comme moyen de prétraitement des armatures, la technique de la cellule de diffusion a montré son efficacité à long terme, grâce à l’augmentation de la période précédant l’amorçage d’une corrosion localisée, où l’armature est en état passif. / Corrosion in prestressed concrete is considered among the most dangerous pathologies in the civil engineering sector. Indeed, this phenomenon is characterized by the seriousness of its economic and security consequences. The objective of this work is to evaluate the efficiency of a phosphate based inhibitor Na3PO4.12H2O against the corrosion of prestressing steels. The study was first conducted on wires tensioned at 80% Rm and immersed in simulating concrete pore solution. Then it concerned, on one hand, prestressed mortar specimens designed on a laboratory scale and, on the other hand, the long term efficiency of the inhibitor using diffusion cell technique. The results obtained from the study carried out in the concrete simulating medium revealed that the presence of the phosphates causes the increase in the critical threshold of localized corrosion initiation R = [Cl -] / [OH-] up to the value of 5 instead of 0.4. This seems to be due to two phosphate inhibiting actions, namely: the stabilization of the iron oxide protective layer and the formation of very insoluble phosphate compounds which block the active anodic sites, increasing prestressing steel resistance to localized corrosion. The use of Na3PO4.12H2O as an additive slightly reduces the compressive strength of the mortar. However, phosphate compounds resulting from the reaction of the inhibitor with the cement hydrates clog the pores of the mortar and slow down the diffusion of the chlorides. This improves the corrosion behavior of prestressed mortar reinforcement. Finally, when sodium triphosphate is used as a migratory inhibitor or as a means of steel reinforcement pretreatment, the diffusion cell technique has shown its long-term efficiency, thanks to the increase of the period preceding the initiation of a localized corrosion, where the reinforcement is in a passive state.