Дисертації з теми "Active interface"

The conflict between stability and curving has been well documented since the dawn of the railways. Advances in computer technology and deeper understanding of the complex mechanics of the wheel-rail interface have led to the study of innovative designs. This thesis outlines the need for steering systems for railway applications. A number of innovative passive solutions have been proposed to reduce the conflict between stability and curving. Comparisons of some of these solutions show that significant benefits can be obtained by using uncommon configurations.

This work was performed in the framework of an interdisciplinary graduate program that focuses on the establishment and extension of innovative compounds for the packaging of electronic systems. Such chemically or biotechnologically tailored compounds can be used for the direct patterning of optically, magnetically or biologically functional structures in nano- and biotechnical products. In order to organize matter at the nanometer scale, imprinting litho-graphy techniques or self-organization processes are appropriate. Fine-tuning of numerous engineering processes requires continuous and high precision monitoring as well as control of diverse parameters. These demands are only partially met by physical or chemical components since they use surrogate parameters, measure off-line, or provide insufficient performances. Biological compounds, in particular protein-based feedback systems, fulfill certain system requirements to a considerable degree. Hydrophobins and S-layer proteins are surface active proteins, produced by filamentous fungi or bacteria. In nature, these (self )assembly proteins form highly ordered and robust structures. In addition, their tolerance for different sequence manipulations and chemical modifications allows extensive functionalization of these nanometer-sized proteins. Hence, these surface active proteins can also be fused with other protein domains to create chimera, which retain function of both original proteins. In conclusion, both hydrophobins and S-layer proteins represent a versatile tool in numerous fields of applied biotechnology, medicine or diagnostics. But until now, efficient in vitro operation in molecular designed protein coatings is strongly restricted due to their complex assembly mechanism. In the first phase of this work, it was demonstrated, that representatives of class I and class II hydrophobins tend to form multilayered structures on solid surfaces. It was found that only two protein orientations seems to be preferentially formed. In the process of assembly, the orientation of the first hydrophobin layer strictly depends on the substrate wettability. Consequently, each of the following hydrophobin layers is inverse oriented to the layer before. This alternating assembly mechanism has to be taken into account, when working with functionalized hydrophobins, because a hydrophobin-fused functional protein domain is exclusively located on one side of the protein. Due to the densely packed structure of surface active proteins, a fused functional domain, embedded between two hydrophobins is barely available for external reagents. Basically, the simultaneous existence of a broad spectrum of ordered and disordered assembly structures, demonstrated the need of an uniform protein film assembly for applications in fine-diagnostics or biomedicine. With regard to molecular designed protein coatings, this work further aimed at establishing conditions to develop a method for a ‘layer-by-layer’ assembly of protein chimeras. Based on their amphiphilic character, self-assembly behavior of surface active proteins can be influenced by conventional ionic surfactants. In order to study the effect of surfactants on the composition and morphology of adsorbed protein films, contact angle measurements, nulling ellipsometry, SEM, AFM and AFAM were performed. It was found that the layer thickness of assembled protein films is strictly dependent on the amount of added surfactant. At certain threshold surfactant concentrations, hydrophobins and S-layer proteins assemble in uniform layers, which are as thick as expected for a protein monolayer or a bilayer. Assembled protein films are covered by a smooth surfactant layer, which prevents further protein assembly. AFAM measurements reveal the formation of well defined lattice structures under the coverage of surfactants. Even the removal of the surfactant layer is possible without inter-fering with protein specific secondary structures. Solvent accessibility and functionality of protein-fused domains was successfully demonstrated. As compared to conventional assembly techniques, this novel protein deposition method offers a possibility for a ‘directed’ protein coating on solid surfaces. In addition, it guarantees broadly ranged homogeneous assembly of protein chimeras on non-planar or even porous surfaces independent of their position. Finally, a prototype for an interfacial FRET was developed in a close collaboration with the Institute of Physical Chemistry (TUD). This innovative FRET between semiconducting nano-particles and illuminating protein chimeras takes place across an oil/water interface. Hydro-phobins were used to stabilize artificial oil droplets in aqueous solution. These small proteins possess the ability to attach fused functional domains very close to an oil/water interface. When, in addition to this, an optically active nanostructure directly docks to the hydrophobin, the distance of a protein-fused domain and the nanostructure are in the range of the FÖRSTER radius. It was successfully demonstrated that quantum dots and fluorescent proteins fulfill the spectroscopic requirements of such a donor/acceptor pair. The FRET performance of these excitable oil droplets was examined as a ‘proof of concept’. Due to its modular design, this signal amplification setup could be exploited in numerous fields of technical application ranging from quantification of micronutrient to photothermal cancer therapy.

Approved for public release; distribution is unlimited
As a piece of critical infrastructure, the Internet brings both benefits and security concerns. Recent cyber-security episodes such as route hijacks and Denial-of-Service attacks might have been mitigated and prevented with better knowledge of the network_s logical topology; i.e., router nodes and links. Current production public active mapping systems; e.g., Ark, Rocketfuel, and iPlane, produce valuable inferences of the Internet_s topology, as well as facilitating longitudinal analysis. We examine the extent to which the techniques utilized by these existing systems can be improved, in particular by attempting to reduce their high probing load. Our methodology divides the discovery process into three steps: destination selection, monitor assignment, and stop criterion. We implement and evaluate alternative designs for each step. The complete system runs in real-time on a production system to probe 500 randomly selected Internet subnetworks and gather real-world network maps. As compared to datasets from existing measurement platforms, we find that our method is able to generate 80% of the amount of data with 69% less load.

In this thesis, we characterize the proprietary active scanning algorithm of several wireless network interface cards. Our experiments are the first of its kind to observe the complete scanning process as the wireless network interface cards probe all the channels in the 2.4GHz spectrum. We discuss the: 1) correlation of channel popularity during active scanning and access point channel deployment popularity; 2) number of probe request frames statistics on each channel; 3) channel probe order; and 4) dwell time. The knowledge gained from characterizing wireless network interface cards is important for the following reasons: 1) it helps one understand how active scanning is implemented in different hardware and software; 2) it can be useful in identifying a wireless rogue host; 3) it can help implement Active Scanning in network simulators; and 4) it can radically influence research in the familiar fields like link-layer handovers and effective deployment of access points.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2005.
"May 2005." Vita.
Includes bibliographical references (p. 23).
The continued development of the Active Joint Brace, a powered orthosis, required that a suitable user interface be designed to control the brace. Since the brace is an electronically-controlled mechanical, medical device, it was important that the user interface (UI) provide both a proper interface to the software that controls the brace, and be in conformance with human factors data. The constraints provided by the existing electronics and software of the brace, combined with suitable ergonomic data, were used to inform the design of a hand-held user interface device, pictured below. The UI features one-handed operation, utilizing an LCD character display and speaker for output devices and a navigation switch for an input device. In preparation for the new UI, the existing menu system was also reorganized for ease-of-use. In preliminary user testing within the development team, the UI has been judged as satisfactory, with only a few minor changes needed to the enclosure.
by Christopher P. Possinger.
S.B.

Organic solar cells (OSCs) have attracted a significant attention during the last decade due to their simple processability on a flexible substrate as well as scope for large-scale production using role to role technique. Improving the performance of the organic solar cells and their lifetime stability are one of the main challenges faced by researchers in this field. In this thesis, work has been carried out using a blend of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) as an active layer in the ratio of (1:1) (P3HT:PCBM). The efficiency and stability of P3HT:PCBM-based solar cells have been examined using different methods and employing novel materials such asl-[N-(2- ethoxyethyl) pent-4-ynamide] -8 (11), 15 (18), 22 (25) - tris -{2-[2-(2-ethoxyethoxy) ethoxy] -l-[2-((2- ethoxyethoxy) - ethoxy) methyl] ethyloxy] phthalocyaninato zinc (II) (ZnPc) to construct a ternary hybrid as the active layer. Controlling the morphology and crystallinity of P3HT:PCBM active layer was carried out using different solvents including chloroform (CF), chlorobenzene (CB) and dichlorobenzene (DCB) and their co-solvents in the ratio of (1:1) to dissolve the P3HT:PCBM blend. Optimum morphology and crystallinity were achieved using a co-solvent made of CB:CF with the obtained solar cell exhibiting the highest performance with PCE reaching 2.73% among other devices prepared using different solvents. Further device performance improvement was observed through optimization of active layer thickness with studied thickness falling in range 65-266 nm. Measurements of the PV characteristics of the investigated OSC devices have revealed optimum performance when active layer thickness was 95 nm with PCE=3.846%. The stability of the P3HT:PCBM-based devices on optimisation of the active layer thickness has shown a decrease in PCE of about 71% over a period of 41 days. Furthermore, P3HT has been blended with different fullerene derivatives (PC60BM, PC61BM, PC70BM and PC71BM) and the active layers were processed using the optimum solvent as well as optimum film’s thickness.

The adsorbed layer morphology of a series of surfactants under different conditions has been examined primarily using atomic force microscopy (AFM). The morphologies of single and double chained quaternary ammonium surfactants adsorbed to mica have been characterised using AFM at concentrations below the cmc. Mixing these different types of surfactants systematically allowed a detailed examination of the change in adsorbed film curvature from the least curved bilayers through to most curved globules. From this study a novel mesh structure was discovered at curvatures intermediate to bilayers and rods. A mesh was again observed in studies examining the morphology change of adsorbed nonionic surfactant films on silica with variation in temperature. Other surfactant mixtures were also examined including grafting non-adsorbing nonionic surfactants and diblock copolymers into quaternary ammonium surfactant films of different morphologies.

The adsorbed layer morphology of a series of surfactants under different conditions has been examined primarily using atomic force microscopy (AFM). The morphologies of single and double chained quaternary ammonium surfactants adsorbed to mica have been characterised using AFM at concentrations below the cmc. Mixing these different types of surfactants systematically allowed a detailed examination of the change in adsorbed film curvature from the least curved bilayers through to most curved globules. From this study a novel mesh structure was discovered at curvatures intermediate to bilayers and rods. A mesh was again observed in studies examining the morphology change of adsorbed nonionic surfactant films on silica with variation in temperature. Other surfactant mixtures were also examined including grafting non-adsorbing nonionic surfactants and diblock copolymers into quaternary ammonium surfactant films of different morphologies.

Les pieux énergétiques constituent une technique récente permettant d’une part le chauffage et la climatisation de bâtiments et assurant d’autre part le rôle de fondations profondes. Cette technique consiste à mettre en place dans des fondations profondes classiques un système échangeur de chaleur. Le principe de transfert de chaleur est similaire à celui utilisé pour des systèmes échangeurs de chaleur conventionnels : un fluide caloporteur permet d’extraire de l’énergie thermique du sol durant l'hiver et d’en injecter durant l’été. Dans le cas de pieux énergétiques, l’interaction entre le sol, le pieu et la structure ne fait pas seulement appel à des considérations mécaniques mais exigent de tenir compte d’aspects thermiques et hydrauliques, ce qui rend relativement complexe la compréhension globale du comportement d’un pieu énergétique. Actuellement, en France, la réalisation effective de pieux énergétiques rencontre un certain nombre de difficultés qui sont en partie liées à une connaissance insuffisante des effets des cycles de température sur la pérennité d’un système de fondations constitué de pieux échangeurs de chaleur. L’objectif de ce mémoire est d’apporter quelques éclairages sur ce sujet, notamment dans le but de contribuer, à terme, à l’élaboration de règles de calcul simples de la portance des fondations profondes énergétiques. Tout d’abord, une synthèse des phénomènes physiques régissant l’interaction thermo-hydro-mécaniques mis en jeu est présentée. Ensuite, considérant le rapport entre le diamètre d’un pieu et sa longueur suffisamment faible, les travaux réalisés se focalisent essentiellement sur les problématiques liées à l’allongement et au raccourcissement du pieu dans sa direction axiale. Différentes modélisation numériques sont effectuées par la méthode des différences finies pour étudier la réponse de pieux énergétiques dans des terrains sans cohésion en tenant compte de différentes conditions aux limites. Le premier modèle est relatif à un pieu énergétique isolé soumis à une seule charge thermique. Le second traite d’un pieu énergétique isolé soumis à une charge axiale mécanique et des variations de température. Le troisième porte sur le comportement des pieux énergétiques appartenant à un groupe de pieux. L’analyse porte en particulier sur l'interaction entre ces pieux et les autres pieux classiques. Dans tous les cas, afin de rendre compte correctement des effets cycliques, l’interface sol-pieu est modélisée par la loi ‘Modjoin’ développée au LGCgE. Enfin, un modèle unidimensionnel basé sur la méthode de courbes de transfert de type t–z est mis en oeuvre. Une loi t–z prenant en compte les effets de chargements cycliques est mise au point. Elle permet notamment de gérer la non-linéarité des phénomènes cycliques et de rendre compte de différents types d’écrouissage
The recent technology for the heating/cooling building system, known as thermo-active piles, has effectively reduced the land use area and drilling cost by incorporating the vertical closed-loop heat exchanger pipes into the pile foundations. The heat transfer principle remains the same with the conventional ground heat exchanger system: an extraction of the steady ground temperature during winter and a recharge of the ground thermal energy during summer. Indeed, the energy transfer in the thermo-active pile system is becoming more complex owing to the thermo-hydro-mechanical interaction between the ground, the aquifer, the concrete pile, and the overlying building. Recently in France, the implementation of this novelty faces some difficulties due to the lack of understanding about the potential impact of seasonal temperature cycles on the environmental sustainability and the structural safety. Considering those concerns, this thesis conducts the study of the thermo-active piles behavior and their interaction with the structure and the environment in the intention to optimize the geotechnical design of such piles according to the French design standard for the deep foundations. First of all, a study of the physical phenomena occurring in the entire system under the thermo-hydro-mechanical interactions is conducted. Since the ratio of the pile diameter and the pile length is very small, the temperature variations in the pile affect mainly the pile axial response. Thus, the study interest is narrowed to the impact of temperature cycles on the pile bearing capacity by paying a particular attention on modeling the soil–structure interaction with finite difference method. A set of three-dimensional numerical models is performed to understand the thermo-active piles response located in cohesionless soil with consideration of several loading stages and various restraint conditions. The first model concerns a single thermo-active pile subjected to a single thermal load, the second deals with a single thermo-active pile under combined axial mechanical and cyclic thermal loads, and the third one is related to the thermo-active piles located in a group of piles to observe the influence on the other classical bearing piles. The need to properly render the cyclic plasticity behavior in such piles is provided by modeling the interface elements at the soil–pile contact zone using the laboratory-developed law named ‘Modjoin’ law. Otherwise, the load transfer t–z method in one-dimensional model can be an alternative solution in the practical geotechnical design, but no t–z law that takes into account the cyclic fatigue effects exists yet. This study carries out a development of the existing t–z law by integrating the nonlinearity condition and cyclic hardening rules

Les arythmies cardiaques représentent environ 50% des maladies cardiovasculaires qui sont la première cause de mortalité dans le monde. Les implants médicaux jouent un rôle majeur dans le traitement de ces arythmies. En France c’est environ 250 000 patients qui sont équipés d’un implant cardiaque et qui nécessitent un suivi régulier. Ces implants utilisent les dernières technologies de micro-nano électronique et possèdent un boitier de stimulation qui est placé en sous-cutané, connecté aux électrodes via une sonde intraveineuse. Un des principaux points faibles de tout implant réside dans l’interface électrode-tissu, en raison d’une réaction inflammatoire soutenue appelée la fibrose. Ce phénomène compromet la biocompatibilité de l’implant, encapsulant la sonde avec un tissu « isolant ». Cela crée des adhérences le long de la sonde et au niveau de l’électrode, ce qui entraine souvent une hausse des seuils de stimulation au cours du temps et une diminution des durées de vie des batteries. Cette réponse est connue et peut être minimisée lors de l’implantation grâce à des sondes à élution de stéroïdes mais la fibrose reste tout de même un obstacle pour les implants, justifiant notre intérêt d’étude sur le long terme de la biocompatibilité des implants cardiaques.La compréhension des mécanismes de la fibrose est primordiale pour ce travail. La fibrose est due à une activation et différentiation de certaines cellules cardiaques sous une contrainte mécanique, et le tissu cardiaque se retrouve modifié localement. Pour caractériser cette modification, on utilise la mesure d’impédance qui consiste à envoyer un courant électrique sinusoïdal I et recueillir la tension résultante U dans le tissu, l’impédance Z est le ratio U/I. en fonction de la fréquence de mesure, on peut explorer le tissu à une échelle microscopique ou macroscopique. Comme les patients sont déjà équipés de sondes cardiaques reliées à un circuit de stimulation qui peut aussi enregistrer l’activité cardiaque, l’idée principale de ce travail est d’examiner l’utilisation d’une mesure électrique qui pourrait caractériser l’encapsulation fibrotique de la sonde, avec pour objectif final d’embarquer cette méthode de caractérisation dans le circuit implanté. Cela nous amène à la problématique de ce projet : est-ce que la fibrose qui se développe autour des sondes cardiaques a une signature électrique ?Mon travail de thèse s’organise en trois axes. Deux axes expérimentaux sont conduits aux niveaux cellulaire et tissulaire. On envisage en plus un axe discutant la faisabilité de mesures d’impédance embarquées pour des conditions proches de l’in vivo. La partie tissulaire ou ex vivo présente la caractérisation de différentes natures de tissu, sain ou collagéneux, et a été développée à l’IHU LIRYC, sur des ventricules de cochons ou de brebis avec des sondes cardiaques implantées chez l’homme. Les spectres d’impédance obtenus sont analysés avec des modèles électriques connus et dont les paramètres sont extraits pour chaque type de tissus. Une analyse statistique montre que les deux natures de tissu sont caractérisées par des paramètres significativement différents. La partie cellulaire ou in vitro présente la caractérisation électrique, par mesure d’impédance, et biologique, par marquages immunocytochimiques, d’un modèle cellulaire de fibrose. Ce modèle est développé en cultivant des cellules cardiaques humaines, activées ou non par un facteur de croissance. Après une analyse statistique, les valeurs d’impédance des cultures activées montrent une différence significative par rapport aux cultures non activées, tandis que la caractérisation biologique montre une augmentation du nombre des cellules activées au cours du temps. Le dernier axe présente des résultats préliminaires sur de mesure d’impédance embarquée en vue d’une utilisation ultérieure in vivo
Cardiac arrhythmias represent about 50% of the cardiovascular diseases which are the first cause of mortality in the world. Implantable medical devices play a major role for treating these cardiac arrhythmias. In France, about 250.000 patients are equipped with an implanted device for arrhythmia treatment and need a regular monitoring. These devices use the latest technology of micro-nano-electronics and integrate a subcutaneous pulse generator connected to electrodes placed into the heart via intravenous leads. One of the main weaknesses of every implantable device lies in the electrode-tissue interface due to a sustained inflammatory response called fibrosis. This phenomenon jeopardizes the device biocompatibility, because it encapsulates the stimulation lead with an “insulating” tissue, creating adherences along the lead and often leading to an increase of the stimulation threshold over time and a larger electrical consumption. This response is well-known and minimized during the implantation surgery thanks the use of steroid-elution electrodes, however fibrosis still remains an impediment even for the most recent devices, enhancing the interest of studying long-term biocompatibility of cardiac implanted devices.The understanding of fibrosis mechanisms is essential for this work. It consists in some cardiac cells activation and differentiation under a mechanical stress, inducing fibrosis initiation and modifying locally the active cardiac tissue. To characterize this modification, we use electrical impedance measurements, consisting in sending a sinusoidal electrical current I and then measuring the resulting voltage U in the tissue; the impedance Z is the U/I ratio. Depending on the frequency of the measurement signal, we can explore the tissue from the microscopic to the macroscopic scales. As a patient is already equipped with cardiac leads connected to a stimulation device which can also record the cardiac electrical activity, the main idea of this work is to investigate the use of an electrical measurement that could characterize the fibrotic lead encapsulation, with the final objective to embed this characterization method in the implanted circuit. This brings us to the main question of our project: does the fibrosis developing around the cardiac leads have an electrical signature?My thesis work is organized along three axes. Two experimental axes are conducted at cellular and tissue levels, on in vitro or ex vivo models. In addition, an axis studying the feasibility of embedded impedance measurement for in vivo mimicking conditions is also discussed. The ex vivo part presents the characterization of tissue of different natures, healthy or collagenous, it was developed with the IHU LIRYC laboratory, on porcine or ovine cardiac tissue (ventricles mainly), with stimulation electrodes used on patients The impedance spectra are analyzed using a known electrical model from which characteristic parameters of the two tissue types are extracted. After statistical analysis, these parameters are found to be significantly different allowing us to distinguish both tissue types. The in vitro part presents the electrical characterization, using impedance measurements, in parallel to the biological characterization, using immunocytochemistry, of a cellular fibrosis model. It consists in culturing human cardiac cells, activated or not by a growth factor. After a statistical analysis, the impedance values show a significantly different signature for cultures with growth factor, with respect to sham cultures, while the biological characterization confirmed the presence of more activated and differentiated cells over time. The last axis gives preliminary results of embedded impedance measurements in custom circuits

Considérant une particule isolée, la différence principale entre un colloïde actif et un colloïde passif réside dans le temps de persistance du régime balistique. La transition du régime balistique vers le régime diffusif est déterminée dans les deux cas par des coefficients de friction ou de manière équivalente par des coefficients de diffusion. Le mouvement d’une particule colloïdale passive micrométrique est diffusif lorsqu’il est observé sur des intervalles de temps d’au moins une microseconde, suffisamment longs pour que la direction de la quantité de mouvement soit rendue aléatoire par des collisions avec les molécules de solvant. A l’échelle macroscopique ces collisions se traduisent par un coefficient de friction de translation. Pour une particule colloïdale active, un mouvement diffusif est observé pour des intervalles de temps de plusieurs secondes, suffisamment longs pour que la direction d’auto-propulsion soit rendue aléatoire par la diffusion rotationnelle de la particule.Dans cette thèse, nous étudions le mouvement d’une particule colloïdale active déposée à la surface de l’eau. Des particules Janus aux propriétés catalytiques ont été préparées par dépôt de platine métal à la surface de particules de silice. La profondeur d’immersion des particules ainsi que leur orientation par rapport à la surface de l’eau ont été caractérisées et discutées en tenant compte des propriétés de mouillage non-uniformes de la surface des particules Janus. Le mouvement de particules isolées en présence de quantités variables d’eau oxygénée utilisée comme source d’énergie, a été enregistré par vidéo-microscopie optique et les trajectoires analysées en termes de déplacement carré moyen et de fonction d’auto-corrélation des vitesses. L’observation de deux types de trajectoires, rectilignes et circulaires, révèle la force effective ainsi que le couple induit par la décomposition catalytique de l’eau oxygénée à la surface de la particule Janus. Le résultat principal de ce travail est que le mouvement des particules actives confinées à l’interface persiste plus longtemps dans le régime balistique que celui de particules actives totalement immergées en solution. Ceci est dû au confinement qui réduit le nombre de degrés de liberté de rotation mais aussi aux conditions de mouillage partiel qui font apparaître des contributions supplémentaires à la friction de rotation
At the single-particle level, the main difference between active colloids and passive ones is the time scale over which the motion crosses over from ballistic to diffusive regime. In both cases, friction coefficients or equivalently diffusion coefficients determine this time scale. For instance, the motion of a passive colloid of 1m radius is diffusive when observed over lag times longer than a microsecond, once the direction of its momentum has been randomized by collisions with solvent molecules. At the macroscopic scale these collisions are accounted for by the translational friction coefficient. For an active colloid the effective diffusive behavior observed over lag times larger than few seconds results from the randomization of the direction of self-propulsion by rotational diffusion. In this thesis we investigated the motion of an active Janus colloid trapped at air-water interface. Spherical catalytic Janus colloids have been prepared through the deposition of platinum metal at the surface of silica particles. Immersion depth of the Janus colloid as well as their orientation with respect to the water surface, has been characterized and interpreted in terms of the non-uniform wetting properties of the Janus particles. The motion of the active Janus colloids in the presence of various concentration of hydrogen peroxide H2O2 as fuel was characterized by video microscopy and the trajectories analyzed through the mean square displacement and the velocity autocorrelation function. The types of trajectories, directional and circular ones that we observed in our experiments, revealed the effective force and torque induced by the catalytic decomposition of H2O2. At the water surface, active colloids perform more persistent directional motions as compared to the motions performed in the bulk. This has been interpreted as due to the loss of degrees of freedom resulting from the confinement at interface and also to the partial wetting conditions that possibly bring new contributions to the rotational friction at interface

This research study focused on the development and subsequent evaluation of an in-vehicle Active Traffic and Demand Management (ATDM) system deployed on I-66. The ATDM elements inside the vehicle allowed drivers to remain consistently aware of traffic conditions and roadway requirements even if external signage was inaccessible. Forty participants were accompanied by a member of the research team and experienced the following features from the in-vehicle device (IVD): 1) dynamic speed limits, 2) dynamic lane use/shoulder control, 3) High Occupancy Vehicle (HOV) restrictions, and 4) variable message signs (VMS). This system was equipped with auditory and visual alerts to notify the driver when relevant information was updated. The research questions addressed distraction, desirability, and driver behavior associated with the system. Participant data was collected from the instrumented vehicle, various surveys, and researcher observation. Analysis of Variance (ANOVA) and Tukey-Kramer tests were performed to analyze participant eye glance durations towards the IVD and instrument cluster. Wilcoxon signed rank tests were used to draw conclusions from participant speed data and some survey responses. Several key findings were uncovered related to each research category: 1) the IVD would not be classified as a distraction according to NHTSA distraction guidelines, 2) seventy-three percent of participants would want the in-vehicle technology in their next vehicle, and 3) the speed limit alert motivated participants to alter their speed (based on both survey results and actual participant speed data).
Master of Science

In this thesis, we study mathematical models that describe the morphology of a generalized biological cell in equilibrium or under the influence of external forces. Within these models, the cell is considered as a thermodynamic system, where streaming effects in the cell bulk and the surrounding are coupled with a Helfrich-type model for the cell membrane. The governing evolution equations for the cell given in a continuum formulation are derived using an energy variation approach. Such two-phase flow problems that combine streaming effects with a free boundary problem that accounts for bending and surface tension can be described effectively by a diffuse interface approach. An advantage of the diffuse interface approach is that models for e.g. different biophysical processes can easily be combined. That makes this method suitable to describe complex phenomena such as cell motility and multi-cell dynamics. Within the first model for cell motility, we combine a biological network for GTPases with the hydrodynamic Helfrich-type model. This model allows to account for cell motility driven by membrane protrusion as a result of actin polymerization. Within the second model, we moreover extend the Helfrich-type model by an active gel theory to account for the actin filaments in the cell bulk. Caused by contractile stress within the actin-myosin solution, a spontaneous symmetry breaking event occurs that lead to cell motility. In this thesis, we further study the dynamics of multiple cells which is of wide interest since it reveals rich non-linear behavior. To apply the diffuse interface framework, we introduce several phase field variables to account for several cells that are coupled by a local interaction potential. In a first application, we study white blood cell margination, a biological phenomenon that results from the complex relation between collisions, different mechanical properties and lift forces of red blood cells and white blood cells within the vascular system. Here, it is shown that inertial effects, which can become of relevance in various parts of the cardiovascular system, lead to a decreasing tendency for margination with increasing Reynolds number. Finally, we combine the active polar gel theory and the multi-cell approach that is capable of studying collective migration of cells. This hydrodynamic approach predicts that collective migration emerges spontaneously forming coherently-moving clusters as a result of the mutual alignment of the velocity vectors during inelastic collisions. We further observe that hydrodynamics heavily influence those systems. However, a complete suppression of the onset of collective migration cannot be confirmed. Moreover, we give a brief insight how such highly coupled systems can be treated numerically using finite elements and how the numerical costs can be limited using operator splitting approaches and problem parallelization with OPENMP
Diese Dissertation beschäftigt sich mit mathematischen Modellen zur Beschreibung von Gleichgewichts- und dynamischen Zuständen von verallgemeinerten biologischen Zellen. Die Zellen werden dabei als thermodynamisches System aufgefasst, bei dem Strömungseffekte innerhalb und außerhalb der Zelle zusammen mit einem Helfrich-Modell für Zellmembranen kombiniert werden. Schließlich werden durch einen Energie-Variations-Ansatz die Evolutionsgleichungen für die Zelle hergeleitet. Es ergeben sie dabei Mehrphasen-Systeme, die Strömungseffekte mit einem freien Randwertproblem, das zusätzlich physikalischen Einflüssen wie Biegung und Oberflächenspannung unterliegt, vereinen. Um solche Probleme effizient zu lösen, wird in dieser Arbeit die Diffuse-Interface-Methode verwendet. Ein Vorteil dieser Methode ist, dass es sehr einfach möglich ist, Modelle, die verschiedenste Prozesse beschreiben, miteinander zu vereinen. Dies erlaubt es, komplexe biologische Phänomene, wie zum Beispiel Zellmotilität oder auch die kollektive Bewegung von Zellen, zu beschreiben. In den Modellen für Zellmotilität wird ein biologisches Netzwerk-Modell für GTPasen oder auch ein Active-Polar-Gel-Modell, das die Aktinfilamente im Inneren der Zellen als Flüssigkristall auffasst, mit dem Multi-Phasen-Modell kombiniert. Beide Modelle erlauben es, komplexe Vorgänge bei der selbst hervorgerufenen Bewegung von Zellen, wie das Vorantreiben der Zellmembran durch Aktinpolymerisierung oder auch die Kontraktionsbewegung des Zellkörpers durch kontraktile Spannungen innerhalb des Zytoskelets der Zelle, zu verstehen. Weiterhin ist die kollektive Bewegung von vielen Zellen von großem Interesse, da sich hier viele nichtlineare Phänomene zeigen. Um das Diffuse-Interface-Modell für eine Zelle auf die Beschreibung mehrerer Zellen zu übertragen, werden mehrere Phasenfelder eingeführt, die die Zellen jeweils kennzeichnen. Schließlich werden die Zellen durch ein lokales Abstoßungspotential gekoppelt. Das Modell wird angewendet, um White blood cell margination, das die Annäherung von Leukozyten an die Blutgefäßwand bezeichnet, zu verstehen. Dieser Prozess wird dabei bestimmt durch den komplexen Zusammenhang zwischen Kollisionen, den jeweiligen mechanischen Eigenschaften der Zellen, sowie deren Auftriebskraft innerhalb der Adern. Die Simulationen zeigen, dass diese Annäherung sich in bestimmten Gebieten des kardiovaskulären Systems stark vermindert, in denen die Blutströmung das Stokes-Regime verlässt. Schließlich wird das Active-Polar-Gel-Modell mit dem Modell für die kollektive Bewegung vom Zellen kombiniert. Dies macht es möglich, die kollektive Bewegung der Zellen und den Einfluss von Hydrodynamik auf diese Bewegung zu untersuchen. Es zeigt sich dabei, dass der Zustand der kollektiven gerichteten Bewegung sich spontan aus der Neuausrichtung der jeweiligen Zellen durch inelastische Kollisionen ergibt. Obwohl die Hydrodynamik einen großen Einfluss auf solche Systeme hat, deuten die Simulationen nicht daraufhin, dass Hydrodynamik die kollektive Bewegung vollständig unterdrückt. Weiterhin wird in dieser Arbeit gezeigt, wie die stark gekoppelten Systeme numerisch gelöst werden können mit Hilfe der Finiten-Elemente-Methode und wie die Effizienz der Methode gesteigert werden kann durch die Anwendung von Operator-Splitting-Techniken und Problemparallelisierung mittels OPENMP

The aim of developing infinite-life autonomous wireless electronics, powered by the energy of the surrounding environment, drives the research efforts in the field of Energy Harvesting. Electromagnetic and piezoelectric techniques are deemed to be the most attractive technologies for vibrational devices. In the thesis, both these technologies are investigated taking into account the entire energy conversion chain. In the context of the collaboration with the STMicroelectronics, the project of a self-powered Bluetooth step counter embedded in a training shoe has been carried out. A cylindrical device 27 × 16mm including the transducer, the interface circuit, the step-counter electronics and the protective shell, has been developed. Environmental energy extraction occurs exploiting the vibration of a permanent magnet in response to the impact of the shoe on the ground. A self-powered electrical interface performs maximum power transfer through optimal resistive load emulation and load decoupling. The device provides 360 μJ to the load, the 90% of the maximum recoverable energy. The energy requirement is four time less than the provided and the effectiveness of the proposed device is demonstrated also considering the foot-steps variability and the performance spread due to prototypes manufacturing. In the context of the collaboration with the G2Elab of Grenoble and STMicroelectronics, the project of a piezoelectric energy arvester has been carried out. With the aim of exploiting environmental vibrations, an uni-morph piezoelectric cantilever beam 60×25×0.5mm with a proof mass at the free-end has been designed. Numerical results show that electrical interfaces based on SECE and sSSHI techniques allows increasing performance up to the 125% and the 115% of that in case of STD interface. Due to the better performance in terms of harvested power and in terms of electric load decoupling, a self-powered SECE interface has been prototyped. In response to 2 m/s2 56,2 Hz sinusoidal input, experimental power recovery of 0.56mW is achieved demonstrating that the device is compliant with standard low-power electronics requirements.

Significant advances in modern ac/ac power converter technologies and demands of industries have reached beyond standard ac/ac power converters with voltage-source inverters fed from diode rectifiers. Power electronics converters have been matured to stages toward compact realization, increased high-power handling capability, and improving utility interface. Modern ac/ac power converter topologies with various control strategies have been introduced for the further improvements, such as matrix converters, current-fed converters, PWM rectifiers, and active power filters. In this dissertation, several new converter topologies are proposed in conjunction with developed control schemes based on the modern ac/ac converters which enhance performance and solve the drawbacks of conventional converters. In this study, a new fault-tolerant PWM strategy is first proposed for matrix converters. The added fault-tolerant scheme would strengthen the matrix converter technology for aerospace and military applications. A modulation strategy is developed to reshape output currents for continuous operation, against fault occurrence in matrix converter drives. This study designs a hybrid, high-performance ac/ac power converter for high power applications, based on a high-power load commutated inverter and a mediumpower voltage source inverter. Natural commutation of the load commutated inverter is actively controlled by the voltage source inverter. In addition, the developed hybrid system ensures sinusoidal output current/voltage waveforms and fast dynamic response in high power areas. A new topology and control scheme for a six-step current source inverter is proposed. The proposed topology utilizes a small voltage source inverter, to turn off main thyristor switches, transfer reactive load energy, and limit peak voltages across loads. The proposed topology maximizes benefits of the constituent converters: highpower handling capability of large thyristor-based current source inverters as well as fast and easy control of small voltage source inverters. This study analyzes, compares, and evaluates two topologies for unity power factor and multiple ac/ac power conversions. Theoretical analyses and comparisons of the two topologies, grounded on mathematical approaches, are presented from the standpoint of converter kVA ratings, dc-link voltage requirements, switch ratings, semiconductor losses, and reactive component sizes. Analysis, simulation, and experimental results are detailed for each proposed topology.

L'objectif de cette thèse est d'étudier les interactions ions/carbone poreux afin d'améliorer les performances de supercondensateurs carbone/carbone. Les Carbones Dérivés de Carbures de titane (TiC-CDC) sont des carbones microporeux, dont la porosité est monodisperse. Ils ont permis d'étudier finement les interactions entre la taille des ions de l'électrolyte et la taille des pores de la matière active (carbone) dans la formation de la double couche électrochimique dans deux différents types d'électrolyte (organique et liquide ionique). Contrairement à ce qui était pensé jusqu'à maintenant, afin de maximiser la capacité et donc l'énergie, la taille des pores du carbone doit être voisine de la taille des ions de l'électrolyte. Il a également été montré que les ions adsorbés à la surface du carbone sont partiellement désolvatés. Lorsque la porosité du carbone est adaptée à la taille des ions de l'électrolyte, on observe une augmentation de 40 % de la capacité en milieu acétonitrile et de 60 % en milieu liquide ionique, ce qui correspond respectivement à un doublement et un triplement de l'énergie maximale des supercondensateurs
The aim of this work is to study ion/porous carbon interactions in supercapacitor electrodes to improve their electrochemical performances. Titanium Carbide Derived Carbon (TiC-CDC) are microporous carbon with monodisperse porosity. They allowed us to finely study the interactions between electrolyte's ion size and active material pore size during the electrochemical double layer formation in two different kind of electrolyte (organic and ionic liquid). Unlike to traditional views, in order to maximise capacitance, carbon pore size must be close to electrolyte ions size. It was demonstrated that ions adsorbed on carbon's surface are at least partially desolvated. As carbon porosity is well adapted to electrolyte ions size, the capacity is improved of 40 % in acetonitrile and 60 % in ionic liquid. This corresponds respectively to an enhancement by two and by three of the energy of supercapacitors

Les prothèses neuronales implantables offrent de nos jours une réelle opportunité pour restaurer des fonctions perdues par des patients atteints de lésions cérébrales ou de la moelle épinière, en associant un canal non-musculaire au cerveau ce qui permet la connexion de machines au système nerveux. La fiabilité sur le long terme de ces dispositifs, se présentant sous la forme d'électrodes implantables, est un facteur crucial pour envisager des applications dans le domaine des interfaces cerveau-machine. Cependant, les électrodes actuelles pour l'enregistrement et la stimulation se détériorent en quelques mois voire quelques semaines. Ce défaut de fiabilité sur le long terme, principalement lié à une réaction chronique contre un corps étranger, est induit au départ par le traumatisme consécutif à l'insertion du dispositif et s'aggrave ensuite, durant les mouvements du cerveau, à cause des propriétés mécaniques inadaptées de l'électrode par rapport à celles du tissu. Au cours du temps, l'ensemble de ces facteurs inflammatoires conduit à l'encapsulation de l'électrode par une couche isolante de cellules réactives détériorant ainsi la qualité de l'interface entre le dispositif implanté et le tissu cérébral. Pour s'affranchir de ce phénomène, la biocompatibilité des matériaux et des procédés, ainsi que les propriétés mécaniques de l'électrode doivent être pris en considération. Durant cette thèse, nous avons abordé la question en développant un procédé de fabrication simple pour réaliser des dispositifs implantables souples en parylène. Les électrodes flexibles ainsi obtenues sont totalement biocompatibles et leur compliance est adaptée à celle du tissu cérébral ce qui limite fortement la réaction inflammatoire occasionnée par les mouvements du cerveau. Après avoir optimisé le procédé de fabrication, nous avons focalisé notre étude sur les performances du dispositif et sa stabilité. L'utilisation d'une grande densité d'électrodes micrométriques, avec un diamètre de 10 à 50 µm, permet de localiser les zones d'enregistrement en rendant possible, par exemple, la conversion d'un ensemble de signaux électrophysiologiques en une commande de mouvement. En contrepartie, la réduction de la taille des électrodes conduit à une augmentation de l'impédance ce qui dégrade la qualité d'enregistrement des signaux. Ici, un polymère conducteur organique, le poly(3,4-ethylenedioxythiophene), PEDOT, a été utilisé pour améliorer les caractéristiques électriques d'enregistrement d'électrodes de petites dimensions. Le PEDOT a été déposé sur la surface des électrodes par électrochimie avec une grande reproductibilité. Des dépôts homogènes avec des conductivités électriques très élevées ont été obtenus en utilisant différents procédés électrochimiques. Grâce à l'augmentation du rapport surface/volume induit par la présence de la couche de PEDOT, une diminution significative de l'impédance de l'électrode (jusqu'à 3 ordres de grandeur) a été obtenue sur une large plage de fréquences. De tests de vieillissement thermique accéléré ont également été effectués sans influence notable sur les propriétés électriques démontrant ainsi la stabilité de la couche de PEDOT durant plusieurs mois. Les dispositifs ainsi obtenus, fabriqués en parylène avec un dépôt de PEDOT sur la surface active des électrodes, ont été testés in vitro et in vivo sur des cerveaux de souris. Un meilleur rapport signal sur bruit a été mesuré durant des enregistrements neuronaux en comparaison avec des résultats obtenus avec des électrodes commerciales. En conclusion, la technologie décrite ici, associant stabilité sur le long terme et faible impédance, a permis d'obtenir des électrodes implantables parfaitement adaptées pour le développement d'interfaces neuronales chroniques
Implantable neural prosthetics devices offer, nowadays, a promising opportunity for the restoration of lost functions in patients affected by brain or spinal cord injury, by providing the brain with a non-muscular channel able to link machines to the nervous system. The long term reliability of these devices constituted by implantable electrodes has emerged as a crucial factor in view of the application in the "brain-machine interface" domain. However, current electrodes for recording or stimulation still fail within months or even weeks. This lack of long-term reliability, mainly related to the chronic foreign body reaction, is induced, at the beginning, by insertion trauma, and then exacerbated as a result of mechanical mismatch between the electrode and the tissue during brain motion. All these inflammatory factors lead, over the time, to the encapsulation of the electrode by an insulating layer of reactive cells thus impacting the quality of the interface between the implanted device and the brain tissue. To overcome this phenomenon, both the biocompatibility of materials and processes, and the mechanical properties of the electrodes have to be considered. During this PhD, we have addressed both issues by developing a simple process to fabricate soft implantable devices fully made of parylene. The resulting flexible electrodes are fully biocompatible and more compliant with the brain tissue thus limiting the inflammatory reaction during brain motions. Once the fabrication process has been completed, our study has been focused on the device performances and stability. The use of high density micrometer electrodes with a diameter ranging from 10 to 50 µm, on one hand, provides more localized recordings and allows converting a series of electrophysiological signals into, for instance, a movement command. On the other hand, as the electrode dimensions decrease, the impedance increases affecting the quality of signal recordings. Here, an organic conductive polymer, the poly(3,4-ethylenedioxythiophene), PEDOT, has been used to improve the recording characteristics of small electrodes. PEDOT was deposited on electrode surfaces by electrochemical deposition with a high reproducibility. Homogeneous coatings with a high electrical conductivity were obtained using various electrochemical routes. Thanks to the increase of the surface to volume ratio provided by the PEDOT coating, a significant lowering of the electrode impedance (up to 3 orders of magnitude) has been obtained over a wide range of frequencies. Thermal accelerated ageing tests were also performed without any significant impact on the electrical properties demonstrating the stability of the PEDOT coatings over several months. The resulting devices, made of parylene with a PEDOT coating on the active surface of electrodes, have been tested in vitro and in vivo in mice brain. An improved signal to noise ratio during neural recording has been measured in comparison to results obtained with commercially available electrodes. In conclusion, the technology described here, combining long-term stability and low impedance, make these implantable electrodes suitable candidates for the development of chronic neural interfaces

Innovation within the field of nanophotonics is fostering the progress in diverse technological fields, spanning light emitting, communication technologies, renewable energies, medical diagnostic and therapy. Among the different classes of nanomaterials that are contributing to such evolution, semiconductor nanocrystals, a.k.a Quantum Dots (QDs), are the most versatile ones. QDs are inorganic semiconductor nanostructures, whose outstanding light emitting performances make them promising competitors to more “conventional” bulk solid-state materials in many commercial applications. The interest on developing QD-based devices spread on a large scale with the development of colloidal synthesis methods. The colloidal approach expedites their processability and integration in light emitting devices with dimensions ranging from the macro- to the nano-scale. In particular, colloidal QDs are suitable active media for the fabrication of compact and flexible solid-state laser sources. Optical properties of QDs are ruled by the Quantum Confinement (QC) regime. The latter occurs when the size of the material is reduced to levels comparable with the exciton Bohr radius. QC is a size-effect and consequently leads to size-dependent absorption and emission properties. Thanks to QC, QDs exhibit well-defined electronic levels, which enable molecular-like optically allowed absorption transitions. At the same, high absorption cross-sections and stabilities typical of bulk semiconductor materials are preserved. In this thesis work an emerging class of colloidal QDs, namely CdSe-CdXZn1-XS core-shell QDs, is investigated. The attention is mainly focused on the optical gain, which represents one of the most inspected and promising applications for QDs. By investigating the Amplified Spontaneous Emission (ASE) of different series of CdSe-CdXZn1-XS heterostructures, this work demonstrates that key properties such as the ASE activation threshold and photo-stability can be optimized by a careful design of the core-shell heterostructure. Guidelines for the synthesis of such best performing optical gain QDs are drawn by means of optical spectroscopy, which provides insights into the correlation between the excitation and relaxation dynamics with the shell thickness, composition and, ultimately, the structure. Basic parameters such as QD dimensions, size dispersion and photoluminescence quantum yield (QY) can be easily extracted from steady-state absorption and emission spectra. Steady-state absorption and phtoluminescence studies on CdSe-CdXZn1-XS QDs were employed as preliminary tools to prove that different shell materials induce distinct exciton confinement, size dispersion and QY. In a second step, Surface Enhanced Raman Scattering (SERS) technique has been employed, for the first time, as a local probe for the study of the core-shell interfaces. SERS permits the analysis of the nanocrystals with the same structural features and lattice dynamics present when the QDs are employed as emitters in photonic devices. Results of this study revealed that the composition of the CdXZn1-XS shell entails a significant structural difference at the core-shell interface. This structural difference modifies the electronic structure within the QDs, since it directly tailors the QC of the electrons and holes. The effect of the core-shell interface on optical properties has been unambiguously detected with the use of transient optical spectroscopy. In this thesis work, transient absorption (TA) and transient PL (tPL) techniques were employed to probe the exciton generation and recombination dynamics. The evolution of the exciton population was compared with kinetic models. Differently from steady-state techniques, transient techniques are sensitive to the nature and time-scales of the different radiative and non-radiative relaxation paths, whose control is crucial for guiding the heterostructure engineering process. The kinetic rates obtained revealed a clear dependence on the core-shell interface and the correlation with SERS results is discussed. The correlation between structure and dynamics was detected from the nanosecond (tPL analysis) down to the sub-nanosecond time scales (TA analysis). A secondary mission of this thesis was also to find a global interpretation of the dynamics of all signals present in TA spectra of the different CdSe-CdXZn1-XS QD series. Pump fluence, shell thickness and composition are the coordinates along which the global analysis has been developed. This step is of pivotal importance in order to identify the mechanisms involved in the optical gain process, whose temporal evolution for QDs systems spans from the picosecond to the few nanosecond time-scale. From the discussion of the results obtained from the different characterization techniques, it emerges that the most efficient way to boost the optical properties of CdSe QDs is the realization of a “graded” CdXZn1-XS shell, with Zn concentration (and confinement potential) gradually increasing along the radial direction. In a single entity, this solution should provide suitable confinement of the charge-carriers from the defective outer surface, prevent defect formation at the core-shell interface due the mismatch between the different materials and, eventually, limit the dot dimensions. Low QD dimensions increase the packing density and limits the scattering losses when QDs are included in a thin film and/or in a solid-state matrix. Such aspects have to be taken into serious consideration in order to increase the performances of a QD-based optical amplifier. Finally, the validity of the hypothesis formulated is experimentally verified by characterizing the bi-exciton radiative recombination, which represents the photo-physical origin of ASE and thus defines the optical gain performances of differently engineered nano-heterostructures. As predicted, best optical gain performances have been achieved from ASE experiments by using CdSe QDs covered with a graded CdS-Cd0.5Zn0.5S-ZnS shell. Therefore, the results obtained from the spectroscopic characterization provide a guideline for the engineering of new synthetic approaches, addressed to the preparation of highly stable core-shell QDs with minimal optical gain activation threshold. Moreover, the rationalization of the dynamics involved in exciton and multi-exciton generation and recombination in core-shell QDs expedites their application in all types of light emitting devices.
Il progresso in svariati settori tecnologici, a partire dai dispositivi emettitori di luce, passando per le aree delle telecomunicazioni e delle energie rinnovabili, fino alla diagnostica medica e alla terapia, è favorito dalla ricerca e dallo sviluppo nel campo della nanofotonica. Tra le diverse classi di nanomateriali che stanno contribuendo a questo avanzamento, i nanocristalli di materiale semiconduttore, alias Quantum Dots (QDs) o Punti Quantici, presentano le proprietà ottiche più versatili. I QDs sono nanostrutture inorganiche di materiale semiconduttore le cui eccezionali prestazioni in termini di emissione di luce li rendono diretti concorrenti dei materiali a stato solido più "convenzionali" in molte applicazioni commerciali. L'interesse a sviluppare dispositivi basati su QDs si è diffuso su larga scala con lo sviluppo di metodi di sintesi di tipo colloidale. L'approccio colloidale facilita la processabilità e l'integrazione in dispositivi emittitori di luce con dimensioni che vanno dal micron a pochi nanometri. In particolare, i QDs colloidali si prestano alla realizzazione di sorgenti laser a stato solido compatte e su substrati flessibili. Le proprietà ottiche dei QDs sono regolate dal confinamento quantistico (QC). Questo regime si instaura quando la dimensioni del materiale sono comparabili con il raggio eccitonico di Bohr. Il QC, in quanto effetto di taglia, rende le proprietà di assorbimento e di emissione di luce dipendenti dalle dimensioni. Grazie al QC, i QDs possiedono livelli elettronici ben definiti e interagiscono con la luce in maniera simile ai sistemi molecolari. Allo stesso tempo, i QDs dimostrano elevate sezioni d’urto di assorbimento e stabilità al danneggiamento, proprietà tipiche dei semiconduttori inorganici. Questo lavoro di tesi è incentrato su una classe emergente di QDs colloidali, ossia QDs “core-shell” composti da CdSe-CdXZn1-XS, aventi cioè un nucleo (“core”) di CdSe, ricoperto da un guscio (“shell”) di CdXZn1-XS. L'attenzione è focalizzata principalmente sulle proprietà di guadagno ottico il quale rappresenta per i QDs una delle applicazioni più promettenti e maggiormente studiate. Attraverso la caratterizzazione dell'Emissione Spontanea Amplificata (ASE) di diverse serie di QDs di CdSe-CdXZn1-XS, questo lavoro dimostra che proprietà chiave come la soglia di attivazione ASE, nonché la stabilità all’irragiamento, possono essere ottimizzate mediante un’attenta progettazione dell’eterostruttura core-shell. Mediante diverse tecniche di spettrocopia ottica è possibile ricavare alcune linee guida per la sintesi di QDs con proprietà di guadagno ottico ottimali. Con queste tecniche è quindi possibile identificare la correlazione tra le dinamiche di eccitazione/rilassamento e la composizione, spessore e, in ultima analisi, struttura del materiale di shell. Parametri di base come le dimensioni medie dei QDs, la dispersione di taglia e la resa quantica di luminescenza (QY) possono essere facilmente estratti dalle tecniche di assorbimento ed emissione in stato stazionario. Queste ultime sono state impiegate come strumenti preliminari per dimostrare che, variando la composizione e lo spessore del guscio esterno di CdXZn1-XS, si altera il grado di confinamento degli eccitoni nel nucleo di CdSe, la dispersione in dimensioni e la QY. In una seconda fase, la tecnica SERS (Surface-Enhanced Raman Scattering o Scattering Raman amplificato da superfici) è stata impiegata per la prima volta come sonda locale per lo studio dell’interfaccia tra core e shell. La tecnica SERS permette la caratterizzazione dei nanocristalli nelle stesse condizioni strutturali e di dinamica reticolare presenti nei QDs quando impiegati come mezzi attivi in dispositivi fotonici. I risultati di questo studio hanno rivelato che la composizione del guscio di CdXZn1-XS comporta delle significative differenze strutturali all'interfaccia core-shell. Questa variazione strutturale modifica la struttura elettronica nei QDs in quanto influenza il grado di confinamento degli elettroni e delle lacune nel core. L'effetto dell'interfaccia core-shell sulle proprietà ottiche è stato inequivocabilmente rilevato mediante l'uso di tecniche di spettroscopia ottica transiente. In particolare, in questo lavoro di tesi sono stati studiati sia l’assorbimento transiente (TA) sia la luminescenza transiente (tPL) ai fini di esaminare le dinamiche di generazione e di ricombinazione degli eccitoni. L’evoluzione della densità eccitonica è stata quindi confrontata con dei modelli cinetici. A differenza delle tecniche a regime stazionario, le tecniche transienti sono sensibili alla natura e ai tempi caratteristici relativi ai diversi percorsi di rilassamento, radiativi e non radiativi, il cui controllo è fondamentale ai fini dell’ingegnerizzazione dell’eterostruttura. I parametri cinetici ottenuti hanno rivelato una chiara dipendenza dall'interfaccia core-shell e la correlazione con i risultati ottenuti mediante SERS sono stati discussi. La correlazione tra struttura e dinamica è stata rilevata a partire dalla scala temporale del nanosecondo (tPL) fino alla scala dei picosecondi (TA). Uno scopo secondario di questa tesi è anche quello di elaborare un'interpretazione globale delle dinamiche di tutti i segnali presenti negli spettri transienti per diverse serie di QDs CdSe-CdXZn1-XS. La densità di eccitazione, lo spessore del guscio e la sua composizione sono le coordinate lungo le quali si è sviluppata tale analisi globale. Questo passo è di cruciale importanza ai fini di identificare i parametri legati al processo di guadagno ottico, i cui tempi caratteristici in sistemi a base di QDs variano dai picosecondi fino a pochi nanosecondi. Dalla discussione dei risultati ottenuti dalle diverse tecniche di caratterizzazione, emerge che il modo più efficace per aumentare le proprietà ottiche dei QDs di CdSe è la realizzazione di un guscio CdXZn1-XS a composizione graduale, in cui la concentrazione di Zn (e di conseguenza il potenziale di confinamento) aumenta gradualmente lungo la direzione radiale. In una sola entità, questa soluzione è in grado di fornire un adeguato confinamento dei portatori di carica dalla superficie esterna, limitare la formazione di difetti all'interfaccia e infine ridurre le dimensioni globali dei QDs. La minimizzazione delle dimensioni permette di aumentare la densità d’impaccamento e limita le perdite dovute allo scattering quando i QDs sono inclusi in una matrice solida e/o depositati come film sottile. Tali aspetti sono di fondamentale importanza ai fini di migliorare l’efficienza di un amplificatore ottico a quantum dots. Infine, la validità delle ipotesi formulate è stata verificata sperimentalmente caratterizzando la ricombinazione radiativa bi-eccitonica, la quale rappresenta l’origine fotofisica dell’ASE e quindi definisce le prestazioni di guadagno ottico delle diverse nano-eterostrutture opportunamente ingegnerizzate. Come previsto, dalle misure di ASE le migliori performance dal punto di vista del guadagno ottico sono state raggiunte utilizzando QDs di CdSe ricoperti con uno shell a composizione graduata di CdS-Cd0.5Zn0.5S-ZnS. I risultati ottenuti mediante la caratterizzazione spettroscopica forniscono dunque una linea guida per la progettazione di nuove strategie di sintesi che siano orientate alla preparazione di QDs altamente foto-stabili e con una soglia di attivazione ASE minimale. In aggiunta, la razionalizzazione delle dinamiche coinvolte nella generazione e ricombinazione eccitonica e multi-eccitonica in QDs core-shell può accelerare la loro applicazione in tutti i tipi di dispositivi emettitori di luce.

Biodynamic feedthrough occurs in many types of operator controlled machines where the operator is a passenger and the motion of the controlled machine excites motion of the human operator, creating unwanted feedback. It is a significant cause for control performance degradation in backhoes. In this research, the problem of biodynamic feedthrough is investigated in a backhoe control system. For simplification, the system is limited to a single degree of freedom. Several controller based approaches are investigated to reduce cab vibration, while maintaining cylinder tracking performance. These controllers are tested in hardware, with and without the human operator and associated biodynamic feedthrough. The effect of this cab vibration reduction on biodynamic feedthrough is tested in a small set of human subject tests. The results indicate that some vibration reduction and improvement in the operator's control performance can be achieved by adding cab vibration compensation.

It has surely happened sometimes to look at the night sky and catch sight of a small, brighting spot moving like an airplane, but without ashing as usually airplane lights do: it was a satellite. It is always amazing to think that there are objects that continously orbit around Earth, so far from us. Maybe, it is not well-known that they are a lot...thousands...more or less 17,000 those closer to the Earth, to be precise. It is difficult to imagine how so much objects can orbit without touching or colliding each other. From the beginning of the space activities in 1957, an enormous number of objects have been sent or released in space, and thinking that space is so limitless that it could contain everything, all these objects have been abandoned in orbit. The result has been the creation of a great quantity of debris that have began to represent a serious threat for future space missions. Recent studies revealed that if no countermeasures are going to be adopted to reduce the generation of debris in orbit, like for example spent spacecraft and orbital stages, the space population could remain stable only for the next 20 - 30 years. Beyond that, collisional cascade events between objects already in orbit will cause a rapidly increase of debris, even in case of a complete hault of launches. This self-sustained phenomenon, known as Kessler Syndrome, would prevent any other human access to space. Although from '90s, mitigation measures have been proposed to limit the generation of debris in orbit, they appeared to be insufficient to guarantee a long term stability of the space environment. The only way to intervene would be the implementation, in parallel, of active debris removal (ADR) missions. The effectiveness of such kind of missions has been demonstrated, but there are numerous aspects that have to be solved yet in order to make them feasible in the near future. On one hand new mission studies and analyses are required to identify the most efficient ADR scenarios. On the other hand, there are several technological issues that are particuarly critical, espacially as regards the capture of space debris, that are essentially un-cooperative objects and so, not-specially-prepared to be grasped. The research developed in this thesis deals with two of the main aspects related to active debris removal: I) ADR mission analysis, II) developement of an enabling technology for ADR; in the specific case, the development of a morphing adhesive interface to capture uncooperative ojects. A multiple vehicles scenario, where orbital transfers and de-orbiting operations are accomplished by distinct vehicles (a space tug for the former, proper de-orbiting kits for the latter), is selected for the analysis. The innovative solution proposed is the employemnt of modular structures as de-orbiting kits, constructed by assembling a certain number of microsatellite elementary units, equipped with proper de-orbiting devices; the number of assembled units depends on the characteristics of the debris, in terms of mass and initial orbit, as well as to the specic de-orbiting technology selected. An increased mission efficiency, reliablity and exibility are expected from the adoption of such approach. Costs and mass savings can be also expected, as well as economy of scale, thanks to the standarization of the units employed. Four de-orbiting solutions are implemented in the analysis: drag sails, electric propulsion, electrodynamic tethers, hybrid propulsion. Different mission scenarios are analysed, to determine the performances of each solution, in terms of de-orbiting kit mass and total de-orbiting time. For each de-orbiting technlogy, a proper base unit is determined. An optimization procedure to perform multiple orbital transfers and, hence, minimize the mass of the propulsion system of the space tug, is also performed. Five orbital bands are identified as priority regions, where debris have mass between 800 kg and 11 tons and orbits between 800 km and 1000 km. The analyses revealed that, although drag sails are low-cost and simple solutions, they are not suitable to de-orbit massive debris from high altitudes since very large sails could be required, with consequent high risk of collisions during the de-orbiting phase. Electric propulsion and electrodynamic tethers are both promising solutions for ADR: for debris with mass 2000 kg they are comparable, both in terms of de-orbiting kit mass and total de-orbiting time. For more massive debris, mass 2000 kg, electrodynamic tethers performes better from the remover mass point of view, but higher de-orbiting time is required compared to electric propulsion. Risks assessment evaluation revealed that in this case the probability for the electrodynamic tethers to be damaged in consequence of collisional events with debris up to 10 cm exceeded the limit of 0.001 indicated in the NASA-STD-8719.14. The risk analyses conducted for electric propulsion, on the other hand, did not reveal any risk of catastrophic collision during the deorbiting manoeuvre. Hybrid propulsion resulted the most massive solution among those implemented, but it represents the fastest solution in terms of de-orbiting time. The second part of the research activity is focused on the development of a morphing adhesive interface to be integrated as end effect of a robotic mechanisms to allow the capture of uncooperative objects. Two technologies are investigated in the realization of the interface: shape memory polymers, for the morphing behaviour, and electroadhesion for the adhesion capabilities. Two prototypes are then developed and tested. It is observed that mechanical pre-load as well as electrostatic force increase the normal adhesion performances of the realised interface. Normal adhesion pressures can vary between 0.55 and 1.4 kPa without the contribution of electrostatic forces, as the mechanical pre-load is varied between 1.5 N and 10 N. The adhesion pressure increases in presence of electrostatic forces, varying between 1.40 kPa and 1.80 kPa for different mechanical pre-load and voltage conditions. The forces achievable range between 3.5 N and 11.5 N. Morphing tests are also performed to verify the morphing-adhesive capabilities of the developed interface. The tests demonstrates taht the presence of a foam substrate could be advantageous as regards the capture of uncooperative objects, allowing a good compliance between two contact surfaces even in presence of macroscopical irregularities, enhancing the adhesion between them. The effectivness of the proposed morphing-adhesive interface is then demonstrated.
Sarà sicuramente capitato qualche volta di guardare il cielo stellato e di scorgere un piccolo puntino luminoso che si muoveva come un aeroplano, ma senza lampeggiare come di solito fanno le luci degli aerei: si trattava di un satellite. E' sempre affascinante pensare che ci sono oggetti che orbitano continuamente attorno alla Terra, così distanti da noi. Forse, non è così noto che ce ne sono davvero tanti...migliaia...17,000 quelli più vicini alla Terra, per la precisione. E' diffcile immaginare come così tanti oggetti possano orbitare senza toccarsi o scontrarsi tra loro. Fin dall'inizio delle attività spaziali nel 1957, un'enorme quantità di oggetti è stata lanciata o rilasciata in orbita, e pensando che lo spazio sia così illimitato da poter contenere ogni cosa, tutti questi oggetti sono stati abbandonati in orbita. Il risultato è stato la creazione di un gran numero di detriti che hanno iniziato a rappresentare una minaccia per le future missione spaziali. Recenti studi hanno rivelato che se proprie contromisure non saranno adottate per ridurre la creazione di ulteriori detriti in orbita, come per esempio satelliti non operativi e stadi orbitali, l'ambiente spaziale potrebbe rimanere stabile solo per i prossimi 20 o 30 anni. Oltre tale termine, potrebbero verificarsi eventi di collisioni in cascata tra gli oggetti attualmente in orbita causando un rapido aumento del numero di detriti, anche nel caso irrealistico di un completo arresto dei lanci. Questo fenomeno autosostenuto, noto come Sindrome di Kessler, potrebbe impedire qualsiasi altra missione nello spazio. Nonostante a partire dagli anni '90 siano state proposte misure di mitigazione per limitare la generazione di detriti in orbita, esse si sono rivelate insufficienti per garantire una stabilità a lungo termine dell'ambiente spaziale. L'unico modo di intervenire è l'implementazione, in parallelo, di missioni di rimozione attive dei detriti spaziali (in inglese Active Debris Removal - ADR). L'efficacia di tali missioni è stata dimostrata, ma ci sono ancora numerose questioni che devono essere affrontate per poterle applicare nella realtà. Da un lato, l'efficienza dei possibili scenari di missione deve essere investigata in modo da individuare le soluzioni migliori. Dall'altro lato ci sono ancora diverse questioni tecnologiche particolarmente critiche, specialmente riguardo la cattura dei detriti, che sono essenzialmente oggetti non cooperativi e quindi non predisposti per essere catturati. La ricerca sviluppata nel presente lavoro di tesi è stata focalizzata su due degli aspetti principali legati all'ADR: I) analisi di missione di ADR e II) sviluppo di una tecnologia chiave per l'ADR; nel caso specifico, di un'interfaccia deformabile adesiva per la cattura di oggetti non-cooperativi. E stato considerato uno scenario di missione basato sull'impiego di veicoli distinti per l'esecuzione dei trasferimenti orbitali e delle manovre di de-orbiting. In particolare, un veicolo di grandi dimensioni per i primi e propri kits di de-orbiting per le seconde. La soluzione innovativa sviluppata è stata l'adozione di strutture modulari per la realizzazione dei kits di de-orbiting: esse consistono nell'assemblare un certo numero di unità base di microsatelliti, equipaggiate con specifici sistemi di de-orbiting; il numero di unità assemblate dipende dalle caratteristiche del detrito, in termini di massa e altezza iniziale, e dalla particolare tecnologia di de-orbiting. Uno scenario di questo tipo comporta una maggiore efficienza, adattabilità e flessibilità. Sono inoltre previsti vantaggi in termini di costo e di massa, con la possibilità di impiegare economie di scala grazie alla standardizzazione delle unità impiegate. Nello studio sono state considerate quattro soluzioni di de-orbiting: vele per l'aumento del drag, propulsione elettrica, filo elettrodinamico (electrodynamic tether) e propulsione ibrida. Diversi scenari di missione sono stati analizzati per determinare le caratteristiche delle soluzioni adottate, in termini di massa del sistema di de-orbiting e di tempo totale di manovra. Per ogni tecnologia è stata dimensionata una unità microsatellite elementare. Inoltre, è stata anche implementata una procedure di ottimizzazione di trasferimenti orbitali multipli per minimizzare la massa del sistema propulsive richiesto. Sono state poi individuate cinque bande orbitali in cui attuare l'ADR, caratterizzate da detriti con masse tra 800 kg e 11 tonnellate, e altezze tra gli 800 km e i 1000 km. Le analisi hanno rivelato che le vele per incrementare il drag atmosferico, pur essendo soluzioni a basso costo e semplici, non sono adeguate per la rimozione di detriti massivi in orbite elevate perchè richiederebbero dimensioni troppo elevate con un aumento della possibilità di collisioni durante la fase di de-orbiting. La propulsione elettrica e il filo elettrodinamico sono entrambe soluzioni promettenti per l'ADR: per detriti con massa minore di 2000 kg le due tecnologie sono comparabili, sia in termini di massa del sistema di rimozione, sia di tempo di de-orbiting. Per detriti più massivi, con massa maggiore di 2000 kg, il filo elettrodinamico è più vantaggioso in termini di massa, ma richiede tempi di de-orbiting molto maggiori rispetto alla propulsione elettrica. La probabilità di avere impatti con detriti fino a 10 cm di diametro è risultata maggiore del limite suggerito nel NASA-STD-8719.14 di 0.001. Nel caso della propulsione elettrica invece, si è ottenuto un rischio di collisioni catastrofiche trascurabile. La propulsione ibrida è risultata la soluzione più svantaggiosa in termini di massa, ma è quella che consente il de-orbiting in tempi più ridotti. La seconda parte dell'attività di ricerca è focalizzata sullo sviluppo di un'interfaccia deformabile adesive che potrebbe essere impiegata come end-effector di un meccanismo robotico per la cattura di oggetti non-cooperativi. Due diverse tecnologie sono state considerate per lo studio: polimeri a memorie di forma, per la capacità di adattarsi a forme differenti, e l'elettroadesione per l'adesione mediante forze elettrostatiche. Due prototipi sono stati realizzati e testati. Dai test è emerso che sia un precarico meccanico che le forze elettrostatiche contribuiscono ad aumentare l'adesione. Si sono ottenuti livelli di pressione normale di adesione dell'ordine di 0.55 kPa - 1.4 kPa senza forze elettrostatiche, con variazione del precarico meccanico tra 1.5N e 10 N. L'adesione aumenta in presenza di forze elettrostatiche, variando tra 1.4 kPa e 1.8 kPa per diverse condizioni di precarico meccanico e voltaggio applicato per generare le forze elettrostatiche. Le forze di adesione ottenute variano tra 3.5 N e 11.5 N. Sono stati eseguiti anche dei test che prevedevano la deformazione del supporto per vericare la capacità di deformazione e adesione in presenza di irregolarità macroscopiche sulla superficie dell'oggetto da catturare. Tali test hanno dimostrato che la presenza di un supporto polimerico tipo schiuma può essere vantaggioso nel caso di cattura di oggetti irregolari, in quanto consente di adeguarsi alla forma della superficie dell'oggetto e aderire anche in presenza di irregolarità. In questo modo l'efficacia della soluzione proposta è stata confermata.

This project involved the co-design of a tangible technology to enrich everyday Kuku Yalanji language use by children and their families, in partnership with the Wujal Wujal Aboriginal Shire Council and community. This thesis contributes the design of a relational language technology, the 'Crocodile Language Friend' talking soft toy with a paired web application, along with novel co-design methods and whole-of-community engagement approaches. The thesis argues that participatory design practices involving tangible technologies can support community alignment of resources and initiatives towards Indigenous language revitalization efforts.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
During the last twenty years the construction field in Brazil has evolved significantly in response to its market growing and competitiveness. However this evolving path has faced many obstacles such as cultural barriers and the lack of efforts to achieve quality at the Brazilian construction site. As one of the causes of this facts the lack of integration between construction and the designing process generates waste, pathologies, work redone and improvised changes originated by incompatible projects which were taken by incapacitated personnel at an inconvenient moment. At the same time, the great amount of information generated on the designing or construction phases is lost due to the lack of an effective coordination of these activities. From this scenario Souza (2001), has developed two management methods in her doctorate thesis named Preparation for the Execution of Buildings (known as PEO) and the Pro-active Coordination (known as CPA), these methods are based on the application of the processes adopted by the French construction industry on Brazilian construction sites. These methodologies aim to establish the integration of the project phases by a set of actions and activities implemented by a system of meetings where the main objective is to discuss the projects and the planning of the construction site seeking to obtain a better quality and better outcome on the productive process. These methodologies aim to bring expressive improvements on the productivity, as well as on the lowering of waste, on the settlement of goals, on planning actions in accordance with all the agents involved and mainly on the reduction of costs allied to higher quality standards. Thus is an objective of this research to implement the Preparation on the Execution of Buildings (PEO) seeking to understand the management of the designing process and its interface with the construction site. The methodology applied on the development of the analysis is classified as qualitative and it will be carried by the practical application of the research and the evaluation of its results. Thus, the study was divided into two stages, one of them intended for a pilot study of PEO in Company A, and the other to the implementation of PEO on the company B. This way, the method was developed from a system meetings entitled structured in three different stages: the release of PEO; the development of PEO and the completion of the intensive phase of PEO, which were performed over a period from two to three months. The data analysis was structured upon five main aspects which were evaluated during the implementation of the method on the studied companies. These aspects were: the actions taken during the PEO phase, the development of the actions and the participation of the agents; the internal structure of the companies analyzed; The management and design coordination and the contract form of the contractors, architects and engineers. The results obtained demonstrated the PEO method's effectiveness and viability while a booster on the improvement of project management. Therefore, it can be concluded that the PEO is feasible to be applied in building construction companies, since this method can contribute to the integration of the design phases and construction, as well as to the improvement of the communication between the agents involved in the building construction field.
Nos últimos 20 anos, o setor da construção civil no Brasil evoluiu significativamente em resposta ao crescimento da competitividade no mercado. Entretanto, nesse processo de evolução ainda têm sido encontradas barreiras culturais e organizacionais, e, sobretudo, dificuldades nos esforços à qualidade nos canteiros de obras brasileiros. Aliada a este quadro, a falta de integração entre as atividades de construir e projetar provoca uma série de desperdícios, patologias, retrabalhos e alterações improvisadas decorrentes de projetos não compatibilizados, ora por ausência de detalhes nos projetos, ora por decisões tomadas por pessoas não capacitadas em momentos inadequados. A partir dessa realidade, Souza (2001) desenvolveu dois métodos de gestão nomeados Preparação da Execução de Obras (PEO) e Coordenação Pró-Ativa (CPA) em sua tese de doutoramento, por meio da transposição desses métodos adotados na gestão da interface projeto-execução de obras na França para a realidade dos canteiros de obras brasileiros. Esses métodos visam à integração das etapas de projeto e obra a partir de um conjunto de ações e atividades realizadas por meio de reuniões sistematizadas voltadas à discussão do projeto, ao planejamento e à organização do futuro canteiro de obras, a fim de obter melhor qualidade e desempenho no processo produtivo. Dessa forma, este trabalho tem como objetivo geral implementar o método da preparação da execução de obras (PEO) a fim de avaliar a interface entre a gestão do processo de projeto e a execução do canteiro de obras. A metodologia adotada para o desenvolvimento deste trabalho é classificada como qualitativa, a qual foi realizada por meio de uma pesquisa-ação, e dividida em duas etapas diferentes, sendo uma destinada ao estudo piloto da PEO na empresa A, e a outra à implementação da PEO na empresa B. Deste modo, a aplicação do método foi desenvolvida a partir de um sistema de reuniões em três fases intituladas: lançamento da PEO; desenvolvimento da PEO e finalização da fase intensiva de PEO, as quais foram realizadas em um período entre dois e três meses. A análise de dados foi estruturada a partir de cinco aspectos principais, os quais foram avaliados durante a aplicação do método nas empresas estudadas, sendo eles: quanto às ações desenvolvidas na fase de PEO, quanto ao desenvolvimento das reuniões e a participação dos agentes; quanto à estrutura organizacional e departamental das empresas; quanto à gestão e a coordenação de projetos; e quanto ao formato de contratação dos projetistas e subempreiteiros. Os resultados obtidos com a realização deste trabalho comprovaram a eficácia do método da PEO e a sua viabilidade enquanto potencializador na melhoria da gestão da interface projeto-execução de obras. Portanto, pode-se concluir que a PEO é viável de ser aplicada em empresas de construção e incorporação de edifícios, uma vez que este método pode contribuir para a integração das etapas de projeto e execução, bem como na melhoria da comunicação e na interação entre os agentes envolvidos na produção de edifícios.

Etude de monomeres liquides ou solides sous l'action des plasmas froids. Influence des parametres du plasma sur la vitesse de polymerisation et la structure chimique de la surface du polymere. Aux interfaces entre le plasma et le polymere, se produisent des reactions qui ont pour origine deux transferts d'energie du plasma. Le transfert indirect, attribue aux rayonnements uv-visible, provoque la polymerisation des acrylates. Le transfert direct, du au bombarbement par des especes metastables, radicaux, ions. . . Sur la surface du polymere, amorce des reactions de modification d'addition ou de terminaison

This thesis describes that it is possible to drive synthetic emotions of an interface agent with an electronic nose system developed at AASS. The e-Nose can be used for quality control, and the detected distortion from a known smell sensation prototype is interpreted to a 3D-representation of emotional states, which in turn points to a set of pre-defined muscle contractions. This extension of a rule based motivation system, which we call Facial Expression Driver, is incorporated to a model for sensor fusion with active perception, to provide a general design for a more complex system with additional senses. To be consistent with the biologically inspired sensor fusion model a muscle based animated facial model was chosen as a test bed for the expression of current emotion. The social agent’s facial expressions demonstrate its tolerance to the detected distortion in order to manipulate the user to restore the system to functional balance. Only a few of the known projects use chemically based sensing to drive a face in real-time, whether they are virtual characters or animatronics. This work may inspire a future android implementation of a head with electro active polymers as synthetic facial muscles.

Le comportement de l’interface acier-béton a une grande importance lorsque la fissuration des structures en béton armé est étudiée. Une approche par éléments finis a été proposée par (Torre-Casanova, 2013) et (Mang, 2016) pour représenter l'interface acier-béton dans les simulations de structures à grandes dimensions Le modèle proposé permet de calculer le glissement tangentiel entre l'acier et le béton. L’objectif de cette étude est d’améliorer ce modèle initial pour le rendre plus efficace et plus représentatif. Le document est découpé en trois parties : 1) Le modèle initial de liaison est évalué. Puis amélioré tant en chargement monotone qu’alterné. Le nouveau modèle est validé par plusieurs applications numériques. 2) L'effet de confinement est implémenté dans le modèle de liaison acier-béton. L'effet sur le comportement structural du confinement actif est étudié en utilisant le nouveau modèle. A partir des simulations proposées, il est montré, par l’utilisation du nouveau modèle, que l’effet de confinement actif peut jouer un rôle sur les comportements monotone que cyclique. 3) L'effet goujon est étudié avec le nouveau modèle liaison acier-béton. Deux campagnes expérimentales différentes sont simulées avec différents modelés de renforts (1D barre et poutre) et d’interface (liaison acier-béton et liaison parfaite). Les résultats montrent que le nouveau modèle de liaison acier-béton permet de mieux reproduire les résultats expérimentaux par rapport au modèle de liaison parfaite aux échelles globale et locale
In numerical applications of reinforced concrete structures, the steel-concrete interface behavior has a vital importance when the cracking properties are investigated. A finite element approach for the steel-concrete interface to be used in large-scale simulations was proposed by (Torre-Casanova, 2013) and (Mang, 2016). It enables to calculate the slip between the steel and concrete in the tangential direction of the interface element representation. The aim is here to improve the initial bond-slip model to be more efficient and more representative. The document is divided into three parts: 1) The existing bond-slip model is evaluated. The bond-slip model is then improved by considering transversal and irreversible bond behaviors under alternative loads. The new bond-slip model is validated with several numerical applications. 2) Confinement effect is implemented in the bond-slip model to capture the effect of external lateral pressure. According to the performed numerical applications, it is demonstrated how the active confinement can play a role, through the steel-concrete bond, during monotonic and cyclic loading cases. 3) Dowel action is finally investigated with the new bond-slip model. Two different experimental campaigns (Push-off tests and four-point bending tests) are reproduced with different reinforcement (1D truss and beam) and interface (new bonds-slip and perfect bond) models. The results show that the proposed simulation strategy including the bond slip model enables to reproduce experimental results by predicting global (force-displacement relation) and local behaviors (crack properties) of the reinforced concrete structures under shear loading better than the perfect bond assumption which is commonly used in the industrial applications

During development, higher organisms grow from a single fertilized egg cell to the adult animal. The many processes that lead to the eventual shape of the developed organism are subsumed as morphogenesis, which notably involves the growth of tissues by repeated rounds of cell division. Whereas coordinated tissue growth is a prerequisite for animal development, excessive cell division in adult animals is the key ingredient to cancer. In this thesis, we investigate the collective organization of cells by cell division and cell death. The multicellular dynamics of growing tissues is influenced by mechanical conditions and can give rise to cell rearrangements and movements. We develop a continuum description of tissue dynamics, which describes the stress distribution and the cell flow field on large scales. Cell division and apoptosis introduce stress sources that, in general, are anisotropic. By combining cell number balance with dynamic equations for the stress source, we show that the tissue effectively behaves as a viscoelastic fluid with a relaxation time set by the rates of division and apoptosis. If the tissue is confined in a fixed volume, it reaches a homeostatic state in which division and apoptosis balance. In this state, cells undergo a diffusive random motion driven by the stochasticity of division and apoptosis. We calculate the effective diffusion coefficient as a function of the tissue parameters and compare our results concerning both diffusion and viscosity to simulations of multicellular systems. Introducing a second material component that accounts for the extracellular fluid, we show that a finite permeability of the tissue gives rise to additional mechanical effects. In the limit of long times, the mechanical response of the tissue to external perturbations is confined to a region of which the size depends on the ratio of tissue viscosity and cell-fluid friction. The two-component description furthermore allows to clearly distinguish the different contributions to the isotropic part of the mechanical stress, i.e., the fluid pressure and the stress exerted by cells. Last but not least, we study the propagation of an interface between two different cell populations within a tissue driven by differences in the mechanical control of the rates of cell division and apoptosis. Combining simple analytical limits and numerical simulations, we distinguish two different modes of propagation of the more proliferative population: a diffusive regime in which relative fluxes dominate the expansion, and a propulsive regime in which the proliferation gives rise to dominating convective flows
Die Entwicklung höherer Organismen beginnt mit einer einzelnen befruchteten Eizelle und endet beim erwachsenen Tier. Die vielen Prozesse, die zur endgültigen Form des entwickelten Organismus führen, werden als Morphogenese zusammengefasst; diese umfasst insbesondere das Wachstum von Geweben durch wiederholte Zellteilungszyklen. Während koordiniertes Gewebewachstum eine Voraussetzung normaler Entwicklung ist, führt übermäßige, unkontrollierte Zellteilung letztlich zu Krebs. In dieser Arbeit untersuchen wir den Einfluss von Zellteilung und Zelltod auf die Organisation von Zellen in Geweben. Die Dynamik wachsender Gewebe wird durch mechanische Bedingungen beeinflusst, die u.a.~Anlass zu Zellbewegungen sein können. Wir entwickeln eine Kontinuumsbeschreibung der Gewebedynamik, die die mechanischen Spannungen und das Zellströmungsfeld auf großen Skalen beschreibt. Zellteilung und Apoptose wirken als Spannungsquellen, die in der Regel anisotrop sind. Indem wir die Erhaltungsgleichung für die Zellanzahldichte mit dynamischen Gleichungen für die Spannungsquellen kombinieren, zeigen wir, dass sich das Gewebe effektiv wie eine viskoelastische Flüssigkeit verhält, deren Relaxationszeit von Zellteilungs- und Apoptose-Raten abhängt. Wenn das Gewebe in einem gegebenen Volumen eingeschlossen ist, erreicht es einen homöostatischen Zustand, in dem Zellteilung und der Apoptose im Gleichgewicht sind. In diesem Zustand unterliegen die Zellen einer diffusiven Bewegung aufgrund der Stochastizität von Zellteilung und Apoptose. Wir berechnen den effektiven Diffusionskoeffizienten als Funktion der Gewebeparameter und vergleichen unsere Ergebnisse sowohl hinsichtlich der Diffusion und als auch der Viskosität mit numerischen Simulationen solcher vielzelliger Systeme. Die Berücksichtigung der extrazellulären Flüssigkeit als einer zweiten Materialkomponente erlaubt uns zu zeigen, dass eine endliche Permeabilität des Gewebes zusätzliche mechanische Effekte bedingt. Auf langer Zeitskalen bleibt die mechanische Reaktion des Gewebes auf externe Störungen auf einen Bereich beschränkt, dessen Größe vom Verhältnis der Gewebeviskosität zum Permeabilitätskoeffizienten abhängt. Die Zweikomponenten-Beschreibung erlaubt darüber hinaus eine klare Unterscheidung der verschiedenen Beiträge zum isotropen Teil der mechanischen Spannung, d.h., des hydrodynamischen und des von Zellen ausgeübten Drucks. Zuletzt untersuchen wir die Dynamik einer Grenzfläche zwischen zwei verschiedenen Zellpopulationen innerhalb eines Gewebes, die durch Unterschiede in der mechanischen Kontrolle der effektiven Zellteilungsraten angetrieben wird. Mithilfe der Kombination einfacher analytischer Grenzfälle und numerischer Simulationen zeigen wir, dass zwei unterschiedliche Ausbreitungsmodi unterschieden werden können: ein diffusives Regime, in dem relative Flüsse die Expansion der stärker wachsenden Zellpopulation dominieren, sowie ein Regime, in dem die Grenzfläche durch konvektive Strömungen angetrieben wird
Les organismes supérieurs se développent à partir d\'une seule cellule fécondée jusqu\'à l\'animal adulte. Les nombreux processus qui conduisent à la forme finale de l\'organisme sont connus sous le nom de morphogenèse, qui comprend notamment la croissance des tissus par des cycles répétés de division cellulaire. Alors que la croissance coordonnée des tissus est une condition nécessaire au développement des animaux, la division cellulaire excessive chez les animaux adultes est l\'ingrédient clé du cancer. Dans cette thèse, nous étudions l\'organisation collective des cellules par division et mort cellulaire. La dynamique multicellulaire des tissus en croissance est influencée par des conditions mécaniques et peut donner lieu à des réarrangements ainsi qu\'à des mouvements cellulaires. Nous élaborons une description continue de la dynamique des tissus qui décrit la distribution des contraintes et le champ d\'écoulement des cellules sur de grandes échelles. La division cellulaire et l\'apoptose introduisent des sources de contraintes qui, en général, sont anisotropes. En combinant l\'équation de conservation du nombre de cellules avec des équations dynamiques des sources de contraintes, nous montrons que le tissu se comporte de manière effective comme un fluide viscoélastique avec un temps de relaxation fixé par les taux de division et d\'apoptose. Si le tissu est confiné dans un volume donné, il atteint un état homéostatique dans lequel division et apoptose s\'équilibrent. Dans cet état, les cellules subissent un mouvement diffusif aléatoire dû à la stochasticité de la division et de l\'apoptose. Nous calculons le coefficient de diffusion effectif en fonction des paramètres du tissu et comparons nos résultats concernant à la fois la diffusion et la viscosité à des simulations numériques de tels systèmes multicellulaires. En introduisant un deuxième composant qui représente le liquide extracellulaire, nous montrons qu\'une perméabilité finie du tissu donne lieu à des effets mécaniques supplémentaires. Dans la limite des temps longs, la réponse mécanique du tissu à des perturbations extérieures est confinée à une région dont la taille dépend du rapport entre la viscosité tissulaire et le coefficient de frottement entre les cellules et le liquide extracellulaire. La description à deux composants permet en outre de distinguer clairement les différentes contributions à la partie isotrope de la contrainte mécanique, c\'est-à-dire la pression du fluide et la contrainte exercée par les cellules. Finalement, nous étudions la propagation d\'une interface entre deux populations de cellules différentes, due à des différences dans le contrôle mécanique des taux de division et de mort cellulaire. En combinant de simples limites analytiques et des simulations numériques, nous distinguons deux modes de propagation différents de la population cellulaire la plus proliférante : un régime diffusif dans lequel les flux relatifs dominent l\'expansion, et un régime de propulsion dans lequel la prolifération domine et entraine des flux convectifs

Nous présentons dans ce mémoire un modèle d'interaction outil-roche qui calcule les efforts de forage en fonction du déplacement dans la roche d'un outil de forage de type PDC, et permet d'évaluer ses propriétés directionnelles, à savoir, son indice d'anisotropie (steerability) et son angle de walk. Le mouvement de l'outil est défini par une translation suivant trois axes et une rotation suivant deux axes. L'angle de tilt, qui définit l'inclinaison de l'outil par rapport à l'axe du trou en cours de forage, est pris en compte dans le calcul des surfaces d'interactions effectives entre les différentes composantes de l'outil (structure de coupe, garde active et garde passive) et la roche. Ce modèle outil est établi à partir d'une modélisation de la coupe de roche par un taillant. Ce modèle de coupe élémentaire est construit de manière à être applicable aux différentes parties de l'outil. Les efforts élémentaires de coupe sont intégrés sur toute la structure de l'outil de forage afin de calculer ses propriétés directionnelles. Le modèle d'interaction outil-roche est validé à partir d'essais de forage directionnel réalisés sur un banc spécialement conçu pour reproduire le comportement des systèmes de forage dirigé existants. Il constitue un outil d'aide à la décision pour la sélection de l'outil de forage en fonction du système au bout duquel il sera fixé. Ce modèle pourra aussi être intégré dans une boucle de régulation automatique ou semi-automatique de contrôle et de correction de la trajectoire en temps réel
This work deals with the formulation of global relationships between kinematic variables describing the penetration of a PDC bit into the rock and drilling forces acting on it. This allows us determine the bit directional properties in terms of steerability, which corresponds to the bit lateral aggressiveness, and walk, which describes the bit azimuth displacement with respect to the side force. The bit kinematic quantities are divided into a three-axis penetration vector and a two-axis angular penetration vector. The bit tilt, which describes the angle between the bit revolution axis and the borehole tangent, is used to compute the effective interaction surface between the bit's different components (cutting structure, active gauge and passive gauge) and the rock. A new cutter-rock interface law is set up and experimentally validated in order to compute elementary forces acting on all parts of a drill bit. Bit directional properties are computed after the integration of these elementary forces. The bit-rock interaction model is experimentally validated with directional drilling tests held on a full-scale drilling bench developed to reproduce Rotary Steerable Systems (RSS) directional behavior. Tests and theoretical results enabled us to fully understand the roles of tilt angle, bit design, operating parameters and rock properties in the deviation process of a PDC bit. The bit-rock interaction model is a decision support tool for optimal drill bit selection according to the RSS being used. It could also be embedded in a real-time Closed-Loop Guided Directional Drilling controller in order to correct the drilling direction or follow a planned borehole trajectory

Ce travail de recherche présente des interfaces électroniques non-linéaires pour des systèmes hybrides de récupération d'énergie combinant des transducteurs piézoélectriques et électromagnétiques. Ces systèmes ont reçu un grand intérêt en raison de leur capacité à convertir les vibrations mécaniques en énergie électrique suffisante pour alimenter des capteurs à faible puissance. Afin d'alimenter ces appareils microélectroniques, une fois l'énergie convertie, une extraction efficace et intelligente doit être mise en place avec une unité dédiée. Les interfaces hybrides non-linéaires proposées dans ce travail, visant à inclure autant de parties électroactives que possible dans le même circuit, permettent une augmentation de la puissance de sortie finale des microgénérateurs concernés, ainsi qu'une solution pour obtenir une valeur commune de charge optimale, même si chacun des éléments traités présentent des principes de fonctionnement et des valeurs de charge optimale différents. Une première solution est dérivée du SSHI (Synchronized Switch Harvesting on Inductor) et se base sur la technique de commutation synchronisée. Cette méthode vise à remplacer l'inductance passive dans l'interface SSHI par un système électromagnétique actif, conduisant à une interface de microgénérateurs entièrement actifs et augmentant la puissance de sortie finale. Une deuxième solution est issue de la combinaison des techniques SECE (Synchronous Electric Charge Extraction) et SMFE (Synchronous Magnetic Flux Extraction), respectivement développées pour les systèmes piézoélectriques et électromagnétiques. Son principe de base consiste à transférer l'énergie de l’élément piézoélectrique vers le transducteur électromagnétique, et ensuite à extraire l'énergie du système électromagnétique, préalablement amplifiée par le transfert de charges issues du dispositif piézoélectrique. La stratégie consistant à inclure autant de parties électroactives que possible dans la même interface électrique ouvre de nouvelles possibilités de combiner plusieurs systèmes électroactifs, constituant des récupérateurs d'énergie hybride, sans inclure des étages supplémentaires dans les circuits, ce qui permet de maintenir une relative simplicité sans perte de puissance significative
In this research work, electronic nonlinear interfaces for hybrid energy harvesting systems combining piezoelectric and electromagnetic transducers are presented. Such systems have received great attention due to their ability to detect mechanical vibrations and convert them into electrical energy sufficient to power low-power sensors. In order to supply these microelectronic devices the generated sinusoidal signal needs to be rectified into a constant DC voltage. In other words, once the energy is converted, a proper and smart extraction of such energy needs to be implemented with a dedicated unit. The proposed nonlinear hybrid interfaces developed in this work, aimed at incorporating as much as electroactive parts as possible in the circuit, not only increase the final output power of the involved transducers but also provide a solution for obtaining a common optimal load value, despite dealing with elements singularly presenting different working principles and values of optimal load, without the use of additional load adaptation stages. A first solution is derived from the previously developed SSHI (Synchronized Switch Harvesting on Inductor) and based on the Synchronized Switching technique. This method aims at replacing the passive inductor in the SSHI interface with an active electromagnetic system, leading to an all-active microgenerators interface and increasing the final output power. A second solution is derived from a combination of the SECE (Synchronous Electric Charge Extraction) and SMFE (Synchronous Magnetic Flux Extraction) techniques. Its main principle consists of transferring the energy from the piezoelectric to the electromagnetic transducer and then extracting the boosted energy from the electromagnetic system. The strategy of including as much as electroactive parts within the same electrical interface open many different possibilities of interfacing more than one electroactive system, constituting hybrid energy harvesters, without including extra circuit stages, thus maintaining a relative simplicity without high power losses

Le champ du traitement des images et des vidéos attire l'attention depuis les deux dernières décennies. Ce champ couvre maintenant un spectre énorme d'applications comme la TV 3D, la télé-surveillance, la vision par ordinateur, l'imagerie médicale, la compression, la transmission, etc. En ce début de vingt et unième siècle nous sommes témoins d'une révolution importante. Les largeurs de bande des réseaux, les capacités de mémoire et les capacités de calcul ont été fortement augmentés durant cette période. Un client peut avoir un débit de plus de 100~mbps tandis qu'un autre peut utiliser une ligne à 56~kbps. Simultanément, un client peut avoir un poste de travail puissant, tandis que d'autres peuvent avoir juste un téléphone mobile. Au milieu de ces extrêmes, il y a des milliers de clients avec des capacités et des besoins très variables. De plus, les préférences d'un client doivent s'adapter à sa capacité, par exemple un client handicapé par sa largeur de bande peut être plus intéressé par une visualisation en temps réel sans interruption que d'avoir une haute résolution. Pour y faire face, des architectures hiérarchiques de codeurs vidéo ont été intoduites afin de comprimer une seule fois, et de décomprimer de différentes manières. Comme la DCT n'a pas la fonctionnalité de multi-résolution, une architecture vidéo hiérarchique est conçue pour faire face aux défis des largeurs de bande et des puissances de traitement hétérogènes. Avec l'inondation des contenus numériques, qui peuvent être facilement copiés et modifiés, le besoin de la protection des contenus vidéo a pris plus d'importance. La protection de vidéos peut être réalisée avec l'aide de trois technologies : le tatouage de méta-données et l'insertion de droits d'auteur, le cryptage pour limiter l'accès aux personnes autorisées et la prise des empreintes digitales active pour le traçage de traître. L'idée principale dans notre travail est de développer des technologies de protection transparentes à l'utilisateur. Cela doit aboutir ainsi à un codeur vidéo modifié qui sera capable de coder et d'avoir un flux de données protégé. Puisque le contenu multimédia hiérarchique a déjà commencé à voir le jour, algorithmes pour la protection indépendante de couches d'amélioration sont également proposées.

Le réglage de la tension et la gestion de la puissance réactive est d’une importance capitale pour le bon fonctionnement du système électrique. Les réseaux de distribution connaissent des modifications profondes qui sont tant techniques avec l’insertion de la production décentralisée ou l’enfouissement des lignes aériennes, que réglementaires avec l’entrée en vigueur des codes de réseaux Européens. Aussi, des alternatives aux réglages traditionnels de tension et la mise en place de contrôle des échanges de puissance réactive à l’interface réseau de transport/distribution peuvent être développées. Dans le cadre de ces travaux de doctorat, une solution basée sur l’amélioration du réglage temps réel des réseaux de distribution ainsi que la mise en place d’une gestion conjointe de la puissance réactive entre les gestionnaires du réseau de transport et distribution a été proposée. Ce réglage temps réel est basé sur une méthode de commande prédictive, et s’appuie notamment sur le régleur en charge ou les productions décentralisées pour réaliser un réglage de la tension au sein d’un réseau de distribution et contrôler les échanges de puissance réactive. Les références de puissance réactive à atteindre à l’interface entre réseau de distribution et de transport sont déterminées par le gestionnaire du réseau de transport pour ses propres besoins et en connaissance des réserves de puissance réactive disponible depuis les réseaux de distribution. Par rapport à la littérature, notre démarche a pour originalité de prendre en compte les problèmes à l’interface des réseaux de distribution et de transport et démontre l’intérêt de mener des études conjointes entre gestionnaires
Voltage and reactive power control are of paramount importance to ensure safe and reliable operation of the power system. Distribution grids are undergoing major changes, namely the insertion of distributed generation and the replacement of overhead lines. Along with these physical evolutions, new distribution networks should comply with the requirements of the European Grid Codes on the reactive power exchange at the HV/MV interface. To handle these new operational concerns, alternative solutions to the traditional voltage and reactive power control can be found. In our work, a scheme based on the evolution of the real-time Volt Var Control (VVC) of distribution networks and a joint coordination for the reactive power management of a HV system has been proposed. The real-time VVC of MV grids is based on a predictive control method. This control uses in a coordinated manner the on load tap changer, the distributed generation and the capacitor banks to enforce a suitable MV voltage profile and an appropriate HV/MV reactive power exchange. The reactive power targets at the HV/MV interface are determined by the Transmission System Operator for its own requirements but considering the true MV reactive power reserve. Compared to the literature, the novelty of our approach consists in considering the concerns at the HV/MV system interface. Next our works have shown the relevance of performing joint transmission and distribution system operators analysis

Groups of animals, bacterial colonies, cellular tissues and assemblies of subcellular extracts are some examples of experimental systems studied in the field of Active Soft Matter. All of them are composed of autonomous self-propelled units that consume and transform energy to generate mechanical work. The interaction between these motile units lead to the emergence of cooperative spatiotemporal patterns, not observed in complex fluids in equilibrium. Despite the morphology and dynamics of these systems are being studied in detail, there is still absence of true control capabilities, which could bring new possibilities in the use or application of active flows. To this end, this thesis aims at the development of strategies to condition active flows by means of non-invasive bounds, namely rheological patterning and confinement, as a tool towards the control of the intrinsic unpredictable chaotic behaviour of active matter systems. The experimental system used here is an active gel based on a mixture of cytoskeletal proteins, created in the laboratory of Z. Dogic from Brandeis University (MA, USA) in 2012. In brief, ATP-fuelled kinesin motor clusters crosslink and drive bundled microtubules, giving rise to an active network of biofilaments that develops far from thermodynamic equilibrium. The active gel can also self-organize at soft interfaces, where it forms a quasi-2d active nematic liquid crystal, which features spontaneous turbulent-like flows. In this thesis, first, we report experimental evidence of the existence of strong hydrodynamic coupling at the oil/water interface, where the active nematic resides, and the influence of the rheological properties of the oil phase. By changing the viscosity of the contacting oily fluid, we alter the morphology and dynamics of the active nematic, which we have characterized. In addition, in collaboration with M. C. Marchetti and S. Shankar from Syracuse University (NY, USA), we have fitted specific data to a hydrodynamical model in order to extract an estimate value for the viscosity of the active material. Second, based on these observations, and with the objective of steering the active flows, we impose viscosity patterns at the interface. For this purpose, we use a thermotropic liquid crystal, which self-assemble in well-known structures with marked anisotropic viscosity, externally- and in situ-tuneable by means of temperature and/or external fields. Under such rheological constraints, the active nematic flows are commanded at will, rapidly organizing either in localized rotating swirls or parallel stripes of aligned microtubule bundles. Through this process, we have also had the opportunity to study the interaction between active and passive nematic liquid crystals, which in this case, serve as reporters of the active flows. Finally, we prepare active emulsions by dispersing droplets of active gel in different fluids. Inside droplets, the active gel condenses at the inner surfaces to create an active nematic spherical shell, which develops in geometrically and topologically constrained conditions. Due to the confinement restrictions, the active nematic develops strikingly periodic dynamics that transmit coherent flows into the confining phase. Here, with experiments and simulations performed by M. Ravnik and Ž. Kos from the University of Ljubljana (Slovenia), we study emulsions of droplets with an active nematic shell dispersed in thermotropic nematic liquid crystals. In particular, we focus on the interaction between active flows and the usually static topological defects induced around inclusions in liquid crystals. To conclude, this work not only increases our fundamental knowledge of both thermotropic (passive) and active nematic liquid crystals but it serves as a starting platform to explore the interaction between these two fluid ordered analogues at the interface. Special emphasis will be put on the implementation of anisotropic patterns at interfaces as it has demonstrated to be key towards controlling active flows.
Sistemes compostos per grups d’animals, colònies de bacteris, teixits de cèl·lules o assemblatges d’extractes cel·lulars, mostren comportaments dinàmics complexos significativament similars tot i que, evidentment, es desenvolupen a escales espai-temps molt diverses. Aquests sistemes, anomenats sistemes actius, estan generalment formats per unitats individuals auto-propulsades que consumeixen energia de l’ambient, a partir de la qual generen forces i treball mecànic. La interacció entre els constituents d’aquests sistemes propicia moviments col·lectius i cooperatius, així com patrons de flux que no s’observen en sistemes similars en equilibri termodinàmic. Tot i que les característiques morfològiques i dinàmiques d’aquests sistemes s’estan estudiant amb detall, manquen encara estratègies per controlar els fluxos actius que se’n deriven. L’habilitat de controlar sistemes actius, no només en facilita la seva caracterització sinó que possibilita l’aplicació dels fluxos que se’n deriven, per exemple, en dispositius. Amb aquest objectiu, aquesta tesi se centra en el desenvolupament d’estratègies per al condicionament i control de fluxos actius mitjançant constriccions que procuren ser no invasives per als materials implicats. El material estudiat consisteix en un gel actiu aquós format per agregats de microtúbuls, reticulats per complexos de motors moleculars. En presència d’Adenosina trifosfat (ATP), els complexos motors exerceixen forces de cisalla locals entre els microtúbuls que, globalment, provoquen contínuament l’extensió, flexió i trencament dels agregats filamentosos. La interacció entre els constituents actius genera fluxos turbulents a escales molt més grans que les pròpies de les unitats constitutives del material. D’altra banda, en presència d’una interfície aigua/oli correctament funcionalitzada, el gel es pot densificar, desenvolupant els seus fluxos en contacte amb la fase oliosa. D’aquesta manera, s’obté un material actiu quasi-bidimensional molt dens, en el qual els filaments interaccionen entre si i s’organitzen en el pla donant lloc a un gel actiu amb ordre orientational. En particular, en aquesta tesi, s’estudiarà l’efecte de l’acoblament hidrodinàmic d’aquest material amb fluids viscosos isotròpics, amb patrons reològics imposats per cristalls líquids i en confinament, com a eines per al control dels fluxos, fins ara, aparentment caòtics i impredictibles d’aquests sistemes actius.

Un Système de Gestion de Bases de Données Multimédia doit être capable de manipuler et gérer les données telles que l'image, le texte, le son ou la vidéo, ainsi que des présentations multimédias. Une présentation synchronise et compose différents objets, chacun possédant des aspects temporels sous forme d'une Ombre Temporelle (constituée d'un délai et d'une durée). La synchronisation est définie par un ensemble de contraintes temporelles. Nous proposons un modèle de comportements d'une présentation dont le but est d'ajouter une nouvelle dimension aux objets pour pouvoir leur associer un comportement particulier au cours de leur présentation. On appelle comportement d'un objet, l'ensemble des actions qu'il est susceptible d'entreprendre suite à des événements lors de sa présentation. Le déroulement de la présentation devient imprévisible et dépend des événements qui se produisent et déclenchent une suite d'actions. L'ensemble des comportements lié à la présentation constitue l'Ombre Comportementale d'un objet. Par exemple, elle permet de traiter l'interaction avec l'utilisateur lors des présentations. Pour montrer la faisabilité de notre approche, nous avons étendu un SGBD à objets existant O2. Ces extensions correspondent à des bibliothèques de classes prédéfinies et réutilisables qui permettent de construire, manipuler, interroger et jouer toutes sortes de présentations.

Communication, coordination and cooperation are critical for a successful organization. This master's thesis work presents a literature study of the factors that influence the interface between Research & development and manufacturing functions. Research & development and manufacturing functions rarely share information among each other and rarely combine their skills and knowledge to produce effective and efficient work within organization. This is due to lack of mutual understanding improper communication and coordination among members in the teams. In the late 1990's, competition, Information Technology proliferation, increasing customer demands for better products at shorter lead times emphasized increased need for effective product development. Each function has its specialization and is effective in their domain. Each department has roles and responsibilities to complete given tasks. But they neglect the organizational and management issues and lack the focus where they are a part of a bigger process (i.e. delivering value to customer and making the company successful at the end of the day). The main focus of the thesis is to give deeper knowledge on communication and coordination between Research and Development and manufacturing. This is achieved by review of the articles, analysis and finally synthesis of literature to develop constructs and analysis models. This will help to understand the factors and its interaction. The factors identified are individual responsibilities, artefacts and system or domain understanding, communication idea, control and role distribution, teams, accessibility and arena for personal meetings and finally overall leadership.

Each factor has its own and unique contribution to success with in the organization. These factors are interrelated and dependent on one another. Artefacts understanding deals with some actions and steps has to be taken in order to executive the give tasks, individual role plays an important role in what sense he\she will contribute to the team as well as to the organization. Even active responsibilities must understand the system or domain and quickly adjust to the environment and get practice on it. Teams are essential tool in any organization, working together creates creative problem solving,  improves effective of communication, improves development skills and ability of an individual, mutual understanding and cooperation among group members all will constitute to the teams. Finally teams are the critical building blocks of an organization. The model developed needs further testing through empirical evidence to increase its validity.

Communication, coordination and cooperation are critical for a successful organization. This master's thesis work presents a literature study of the factors that influence the interface between Research & development and manufacturing functions. Research & development and manufacturing functions rarely share information among each other and rarely combine their skills and knowledge to produce effective and efficient work within organization. This is due to lack of mutual understanding improper communication and coordination among members in the teams. In the late 1990's, competition, Information Technology proliferation, increasing customer demands for better products at shorter lead times emphasized increased need for effective product development. Each function has its specialization and is effective in their domain. Each department has roles and responsibilities to complete given tasks. But they neglect the organizational and management issues and lack the focus where they are a part of a bigger process (i.e. delivering value to customer and making the company successful at the end of the day). The main focus of the thesis is to give deeper knowledge on communication and coordination between Research and Development and manufacturing. This is achieved by review of the articles, analysis and finally synthesis of literature to develop constructs and analysis models. This will help to understand the factors and its interaction. The factors identified are individual responsibilities, artefacts and system or domain understanding, communication idea, control and role distribution, teams, accessibility and arena for personal meetings and finally overall leadership. Each factor has its own and unique contribution to success with in the organization. These factors are interrelated and dependent on one another. Artefacts understanding deals with some actions and steps has to be taken in order to executive the give tasks, individual role plays an important role in what sense he\she will contribute to the team as well as to the organization. Even active responsibilities must understand the system or domain and quickly adjust to the environment and get practice on it. Teams are essential tool in any organization, working together creates creative problem solving,  improves effective of communication, improves development skills and ability of an individual, mutual understanding and cooperation among group members all will constitute to the teams. Finally teams are the critical building blocks of an organization. The model developed needs further testing through empirical evidence to increase its validity.

Ce travail de thèse a été consacré à l’étude de la stabilité dans différents milieux des matériaux constitutifs de la couche active des cellules solaires organiques. Les deux objectifs principaux étaient premièrement d’approfondir la compréhension sur certains mécanismes complexes intervenant dans la couche active, et deuxièmement d’étudier les processus de dégradation intervenant spécifiquement aux interfaces de la couche active au sein de la cellule. La première partie de ce mémoire est consacrée à l’étude de la dégradation photochimique et thermique de la couche active des cellules solaires en faisant varier le matériau polymère qui la constitue. La deuxième partie est dédiée au rôle d’un troisième composant de la couche active que peut être la présence d’additifs résiduels provenant de la mise en forme, ou d’un additif stabilisant ajouté à dessein. La troisième partie est consacrée au processus de délamination susceptible d’intervenir à l’interface couche active / couche transporteuse de trous. Enfin, une dernière partie concerne l’étude de l’alignement des niveaux énergétiques entre la molécule de C60 et divers substrats transporteurs d’électrons. L’influence de la lumière et de la température sur les propriétés d’interface couche active / couche transporteuse d’électrons est également reportée
This word was devoted to the stability in various conditions of materials used in the active layer of organic solar cells. The main goals of this work were first to provide deeper understanding about complex mechanisms occurring in the active layer and second to investigate interfacial degradation pathways involving the active layer. A first part was dedicated to the photo and thermal stability of the polymer blend materials which constitute the active layer of the solar cells. A second section focused on the role of the third component of the active layer which can be undesired residual additives coming from the processing or the desired insertion of a stabilizer additive. A third part concerned the delamination issue which takes place at the active layer / hole transporting layer interface. Finally, a last section was devoted to the energy level alignment between the C60 molecules and various electron transporting substrates. The photo and thermal stability of the active layer / electron transporting layer interface was also studied in this section