Le processus de migration est un processus moléculaire intégré qui contribue in vivo à de nombreux processus physiologiques de motilité, comme le développement, la surveillance immunitaire et les métastases du cancer. Pour comprendre la migration cellulaire, il est nécessaire de considérer l'environnement de la cellule, le type de cellules et la morphologie ainsi que l'organisation interne, i.e. son cytosquelette et ses adhérences focales. Ce travail se concentre sur l'étude de la migration de cellules cancéreuses de la vessie sur des supports déformables. L'analyse de trois lignées cellulaires de capacité métastatique différente est présentée. La capacité des cellules cancéreuses à réagir à leur environnement est analysée et le processus de migration est décrit en termes de contraintes de traction. La réorganisation interne de la structure des cellules est étudiée par l'observation microscopique des filaments d'actine, des moteurs de myosine et des sites de transmission de force, i.e. les adhésions focales. On s'intéresse à la relation de complémentarité entre les différentes capacités invasives des cellules cancéreuses, les forces de traction ainsi que les forces exercées sur le lamellipode et les structures internes des cellules. Il est constaté que plusieurs paramètres peuvent être utilisés pour discriminer la capacité métastatique, comme le type de migration, les forces de traction, les zones focales d'adhésion, ainsi que l'indice de diffusivité de migration. Cette étude constitue donc une première tentative pour différencier diverses cellules invasives en utilisant la migration sur des substrats mous. / The migration process is a physically integrated molecular phenomena that contributes to many physiological motility in vivo processes such as development, immune surveillance and cancer metastasis. To understand cell migration it is necessary to consider the cell's environment, cell type and morphology as well as the internal organization of the cells, i.e. its cytoskeleton and focal adhesions. This work focuses on the study of migrating bladder cancer cells on two--dimensional deformable substrates. The analysis of a panel of three cell lines with different invasive capacity is presented. The ability of cancer cells to respond to their environment is analysed and the migration process is described in terms of traction stresses. The internal reorganization of cells structure is studied by microscopic observation of the actin filaments, the myosin motors and the sites of force transmission, i.e. the focal adhesions. The complementary relationship among different invasive capacities of cancer cells, traction stresses as well as the forces exerted on the lamellipodium and internal structures of cells are discussed. It is found that several parameters can be used for discriminating invasiveness, such as migration type, traction forces, focal adhesion areas, as well as the migration diffusivity index. This study therefore constitutes a first attempt to differentiate various invasive cells using migration on soft substrates.

Les machines électriques classiques comme les machines asynchrones et les machines à aimant permanent sont largement utilisées dans ces applications de traction, et surtout en traction ferroviaire. Cette thèse évalue la contribution d'un autre type de machines, appelé machines synchrones à double excitation dans cette même application. Le terme double excitation signifie que le flux de la machine est créé par deux sources : le bobinage d'excitation et les aimants permanents. Le degré de liberté fourni par le bobinage d'excitation permet d’atteindre l’objectif d’amélioration de l’efficacité. Ce travail a pour but d’identifier les avantages des machines à double excitation sur un cycle de conduite spécifique. Il définira également les cas dans lesquels cette machine fournira de meilleures performances que celles des machines classiques.Les études récentes considèrent uniquement l’optimisation des systèmes en optimisant chaque composant du système séparément. Cependant, avoir les meilleurs performances dans chacun de ces composants ne signifie pas avoir un meilleur système. Afin d'atteindre des résultats plus réalistes, un modèle multi-physique prenant en compte la non linéarité des matériaux sera développé. Ce modèle intègre également les différents aspects comme l’électromagnétisme, la thermique, la mécanique et l’électronique de puissance. / Classical electrical machines such as asynchronous and permanent magnet synchronous machines have been widely applied in traction applications and particularly in railway traction. This thesis, however, evaluate the contribution of a special class of synchronous machine called textbf{D}ouble textbf{E}xcitation textbf{S}ynchronous textbf{M}achine (DESM) for the railway traction. Double excitation term indicates that the field flux of the machine is created by two sources: excitation windings and permanent magnets. The degree of freedom provided by the excitation windings provides the opportunity to work on the energy efficiency improvement target. This thesis will try to answer the question whether DESM is more advantageous over classical machines in a specific driving cycle and in addition, in which cases a DESM performs better.Recent studies have merely optimized the individual components, the major drawback of this approach is that the combination of the best individuals does not necessarily form a best system. In order to achieve more realistic results, a multi-physic models taking into account nonlinear characteristic and various disciplines such as electromagnetic, thermal, mechanical and power electronics will be developed.

A novel continuously variable transmission has previously been designed that is capable of addressing a number of concerns within the automotive industry such as reduced emissions. At the commencement of this research, the design was in the early stages of development and little attempt had been previously made to optimise the design to meet specific measurable targets. This thesis utilises and modifies several design approaches to take the design from the concept stage to a usable product. Several optimisation techniques are adapted and created to analyse the CVT from both a design and tribological prospective. A specially designed optimisation algorithm has been created that is capable of quickly improving each critical component dimension in parallel to fulfil multiple objectives. This algorithm can be easily adapted for alternative applications and objectives. The validity of the optimised design is demonstrated through a simulation-tool that has been created in order to model the behaviour of the CVT in a real automotive environment using multiple fundamental theories and models including tire friction and traction behaviour. This powerful simulation tool is capable of predicting transmission and vehicular behaviour, and demonstrates a very good correlation with real-world data. A design critique is then performed that assesses the current state of the CVT design, and looks to address some of the concerns that have been found through the various methods used. A specific prototype design is also presented, based on the optimisation techniques developed, although the actual creation of a prototype is not presented here. Additional complementary research looks at the accuracy of the tire friction models through the use of a specially design tire friction test rig. Furthermore, a monitoring system is proposed for this particular CVT design (and similar) that is capable of continuously checking the contact film thickness between adjacent elements to ensure that there is sufficient lubricant to avoid metal-on-metal contact. The system, which is based around capacitance, requires the knowledge of the behaviour of the lubricant’s permittivity at increased pressure. This behaviour is studied through the use of a specially-designed experimental test rig.

A proposta do presente trabalho é a simulação do sistema de tração elétrica metroferroviária alimentada em corrente contínua. Para isto, o trabalho é iniciado com uma caracterização das instalações móveis e fixas do sistema de tração elétrica. Sobre as instalações móveis, o trabalho dedica um capítulo sobre a dinâmica do movimento e outro sobre os acionamento alimentados em corrente contínua. Sobre as instalações fixas, um capítulo trata dos elementos e configurações da rede de alimentação além de trazer cálculos simples da queda de tensão. Outro capítulo é dedicado exclusivamente ao circuito de retorno e aterramento. Após esta caracterização, o trabalho traz, baseado nos capítulos anteriores, um capítulo sobre a modelagem e a simulação das instalações fixas e móveis. Por fim, um estudo de caso é feito para ilustrar o que foi apresentado. / The proposition of this work is the simulation of DC-fed railway and subway systems. To achieve this proposition, this work starts with the characterization of rolling stock and fixed installations. For rolling stock characterization, this work presents one chapter about train dynamics and other chapter about DC-fed traction drives. For fixed installations characterization, this work presents one chapter about fixed installation components, its configuration and also shows some simple voltage drop calculations. The following chapter describes the traction ground system. After these characterizations, the next chapter deals with modeling and simulation of the entire system. To illustrate this work a case study is presented.

"Cell traction force is generated in the cytoskeleton by actomyosin activity and plays an important role in many cellular processes. In previous cell traction force experiments performed by our lab, unexpectedly large variations were measured. Because these experiments were utilizing a cell population of randomized phase, and there had been no documented investigation into whether cell phase affected cell traction force generation or propagation, it was hypothesized that there would be a significant difference in traction force between S phase and the other phases of interphase, as the physical and chemical changes happening within the nucleus at this time might elicit changes within the cytoskeleton. To test this hypothesis, we characterized the time-evolution of traction forces from a population of synchronized 3T3 fibroblasts. 3T3 fibroblasts were synchronized in G1-phase via serum starvation. The transition times between cellular phases during the first cell cycle after synchronization were identified by BrdU and Hoechst staining at different time points. After phase transition times were approximated, the traction forces of 9 cells were measured in 4-hour intervals for 24 hours. The differences between traction forces measured in G1, S, and G2 phases are not significant, demonstrating that cellular phase does not significantly affect traction force magnitude."

Thesis (doctor)--Technische Universiteit Delft, 1997. / Vita. Includes bibliographical references (p. [153]-162).

Thesis (doctor)--Technische Universiteit Delft, 1997. / Vita. Includes bibliographical references (p. [153]-162).

Th. doct.-ing.--Électrotech.--Toulouse--I.N.P., 1981. N°: 157.

A proposta do presente trabalho é a simulação do sistema de tração elétrica metroferroviária alimentada em corrente contínua. Para isto, o trabalho é iniciado com uma caracterização das instalações móveis e fixas do sistema de tração elétrica. Sobre as instalações móveis, o trabalho dedica um capítulo sobre a dinâmica do movimento e outro sobre os acionamento alimentados em corrente contínua. Sobre as instalações fixas, um capítulo trata dos elementos e configurações da rede de alimentação além de trazer cálculos simples da queda de tensão. Outro capítulo é dedicado exclusivamente ao circuito de retorno e aterramento. Após esta caracterização, o trabalho traz, baseado nos capítulos anteriores, um capítulo sobre a modelagem e a simulação das instalações fixas e móveis. Por fim, um estudo de caso é feito para ilustrar o que foi apresentado. / The proposition of this work is the simulation of DC-fed railway and subway systems. To achieve this proposition, this work starts with the characterization of rolling stock and fixed installations. For rolling stock characterization, this work presents one chapter about train dynamics and other chapter about DC-fed traction drives. For fixed installations characterization, this work presents one chapter about fixed installation components, its configuration and also shows some simple voltage drop calculations. The following chapter describes the traction ground system. After these characterizations, the next chapter deals with modeling and simulation of the entire system. To illustrate this work a case study is presented.

La croissance du trafic ferroviaire prévue dans les années à venir pousse les acteurs du système d'électrification ferroviaire à chercher des solutions innovantes leur permettant d'assurer la consommation d’énergie qui y est liée. Une des solutions concerne l'intégration de moyens de production décentralisés et des systèmes de stockage d'énergie dans les installations fixes de traction électrique (IFTE). Dans cette évolution, la thèse vise à contribuer à la conception d'un outil de dimensionnement et de gestion énergétique intelligente des IFTE hybrides (IFTEH). La première partie décrit une méthodologie de conception technico-économique d’IFTEH. A partir d'une architecture générique d'IFTEH, une démarche d'optimisation sur cycle des variables dimensionnelles, mais également des variables de commandes du système de pilotage est proposée. La modélisation en flux d'énergie de l'IFTEH permet ensuite d’appliquer la méthodologie d’optimisation sur un cas d’étude et de comparer plusieurs scénarios d’optimisation. Après le dimensionnement de l'IFTEH, une méthodologie de gestion énergétique est développée afin de répondre aux objectifs énergétiques, économiques et environnementales, à différents horizons temporels de supervision d'IFTEH. Plusieurs scénarios de gestion sont évalués en simulation à travers des indicateurs de performance représentatifs des gains du système. Une étude d’optimisation des paramètres de supervision apporte des réponses concernant l’influence du dimensionnement du système sur la gestion énergétique. Enfin, la robustesse de la supervision énergétique d’IFTEH est analysée lors de la validation expérimentale à l’échelle de puissance du laboratoire. / In railway traffic increasing and electricity market liberalization context, railway actors are determined to consider innovative solutions to handle the increasing energy demand for electrical traction. One of the solution concerns the integration of decentralized production and energy storage systems in the railway power substations (RPS). The present research work aims to contribute to the design of a sizing and intelligent energy management tool for the hybrid RPS (HRPS). In the first part of the dissertation, a methodology for the techno-economical design of the HRPS is described. From a HRPS generic architecture, an optimization approach is proposed by considering cycles of dimensional and system control variables. Furthermore, an energy flow model permits to apply the optimization methodology on a study case and to compare different optimization scenarios in order to analyze the sizing and optimal planning of electrical sources and loads for a typical day. After sizing the HRPS, an energy management methodology is developed in order to achieve energy, economic and environmental objectives at different time levels of HRPS supervision. Several energy management scenarios are evaluated in simulation through adapted system gain indicators. An optimization study of the supervision parameters provides additional answers concerning the influence of the system design on its management strategy. Eventually, the HRPS energy management robustness is analyzed during an experimental setup phase at laboratory power scale.