Réalisé dans le cadrr du pôle de compétitivité Véhicule du Futur » de la région ,11k.c Franche Comté_ cc uas_ul de thèse porta sur la hmblcmatsque du remplacement des étoffes complexes textiles utilisées dans les applications d'habillage intérieur automobile. La législation sur les véhicules hors d'usage impose des produits automobiles a 1$" ), rccyclablcs et t 95' réutilisables dl ici janvier 2015. Alin de rebondie u la problématique posée ainsi qua la législation Europécnnc, des industriels et des acteurs de la recherche de la regain mulhousienne ont lias aillé ensemble dans le cadre du poilez VERTILAP" sur le développement d'un nouveau textile non-tissé 3D. Ce travail de thèse a eu pour objectif de développer le proucde de ! abris ation de ces nouveaux matériaux ainsi que les produits non-tisses 3D obtenus. La démarche de développements procédé produits a consisté Ii faire évoluer le prototype expérimental VERTILAP' au travers de la caractérisation physique et mécanique en compression des produits obtenus. Des méthodes ci dcsj outils de caractérisations adaptés a ces nouveaux produits ont etc mis au point. L'analyse de résultats obtenus s'est appuyée sur les outils statistiques i abn de valider ces résultats. Une étude comparative avec les produits contenant de la mousse polyuréthane (PU) a permis de montrer que ces nouveaux non-tissés 3D pouvaient être utilisés en remplacement des mousses PU. La réalisation de prototypes pour des applications d'habitacle autinnobilu a été faite et a prouvé la faisabilité industrielle d'un tel remplacement. Les résultats de ce travail ont été utilisés pour [élaboration du cahier des charges d'ur prototype semi industriel VERTILAP".

Pinus radiata is by far the dominant species grown in New Zealand plantations as a renewable source of wood. Several wood quality issues have been identified in the material produced, including the high incidence of compression wood, which is undesirable for end users. At present our understanding of the complex array of developmental processes involved in wood formation (which has a direct bearing on wood quality) is limited. Hence, the forest industry is interested in attaining a better understanding of the processes involved. Towards this goal, and for reasons of biological curiosity, the experiments described in this thesis were carried out to investigate several aspects of xylem cell development. In an in arbor study, changes in the orientation of cortical microtubules and cellulose microfibrils were observed in developing tracheids. Results obtained provide evidence that cortical microtubules act to guide cellulose synthase complexes during secondary wall formation in tracheids. The mechanisms involved in controlling cell wall deposition in wood cells are poorly understood, and are difficult to study, especially in arbor. A major part of this thesis involved the development of an in vitro method for culturing radiata pine wood in which hormone levels, nutrients, sugars and other factors, could be controlled without confounding influences from other parts of the tree. The method developed was used in subsequent parts of this thesis to study compression wood development, and the influence of the hormone gibberellin on cellulose microfibril organisation in the cell wall. Results from the in vitro compression wood experiments suggested that: 1. when a tree is growing at a lean, the developing cell wall was able to perceive compressive forces generated by the weight of the rest of the tree, rather than perceive the lean per se. 2. ethylene, rather than auxin, was involved in the induction of compression wood. Culture of stem explants with gibberellin resulted in wider cells, with steeper cortical microtubules, and correspondingly steeper cellulose microfibrils in the S2 layer of developing wood cells. This observation provides further evidence that the orientation of microtubules guides the orientation of cellulose microfibrils. Overall, the work described in this thesis furthers our knowledge in the field of xylem cell development. The stem culture protocol developed will undoubtedly provide a valuable tool for future studies to be carried out.

Digital image compression is more and more in demand as our society becomes more information oriented, with more digital images being acquired, transmitted and stored everyday. Error-free, or non-destructive, image compression is required in applications where the final image is to be analyzed digitally by computers. A new error-free digital image compression algorithm, the Classifying-Sequencing algorithm, is presented in this dissertation. Without the help of any statistics information of the images being processed, this algorithm achieves average bits-per-pixel close to the entropy of the neighboring pixel difference. In other words, the compression results are comparable to the best that a statistics code can achieve. Because this algorithm does not involve statistical modeling, generation of a code book, or long integer/floating point arithmetics, it is simpler and therefore faster than the standard statistics codes, such as Huffman Code or Arithmetic Code. In this dissertation the new algorithm under discussion is tested using seven images, together with several known algorithms. Three lower-order entropies of the image files are also provided for comparisons. Presenting compression results from an isolated algorithm is not sufficiently objective for comparisons between algorithms, as potential discrepancies exist between not only different images but also same images when reproduced from prints. Comparing the results of different algorithms and with the entropy of the neighboring pixel differences on the same images is more objective. When the entropy of an image is high, the compression ratios of all algorithms are likely to be low; and vice versa. Given that it is faster in decoding than in encoding images, the most prospective applications of the Classifying-Sequencing algorithm are in the fields of digital image transmission, distribution and archiving, where the images are likely to be encoded once but decoded many times. It can be easily realized on simple processors, or completely in hardware, due to its simplicity.

Bacterial adhesion is the first step of biofilm formation that plays various roles in the environment and the human body. Examples of undesirable roles of biofilm formation include metal rust, sewage sludge and bacteria-related diseases. Desirable roles are biofiltration and bioremediation.For a decade, Atomic Force Microscopy (AFM) has been the primary tool used to study the adhesion and elastic properties of individual bacteria. In this work we show it is possible to use a Surface Forces Apparatus (SFA) to measure elastic and adhesive properties of small collections of surface bound bacteria. The measurements are conducted with incomplete, patterned bacterial films and we have developed a protocol to image the contact area with AFM after the experiment. Using the SFA, we measured the force profile between a P. Aeruginosa PAO1 film and a bare mica surface. We repeated the measurement in the same contact position for up to ten days to determine the effect of desiccation on the film material properties, and then moved to the new contact area to measure the film thickness and elastic properties. A large shrinkage of the bacterial film thickness was measured during the first few days due to the bacterial film desiccation and rearrangement. The proportion of shrinkage depends on factors such as the bacterial film coverage, roughness, temperature and relative humidity. Thickness compressibility was estimated from the force curves. As a force approximation, the stress at the center of the contact (σ) and the area of the contact were estimated by applying the Hertz model. Since the film is incomplete the calculated area in contact was reduced by a factor estimated from the optical image of the contact zone. Adhesiveness was measured in receding force profiles. Maximum adhesive force was detected in the first day, due to the high capillary force, decreased by the bacterial film desiccation and increased again due to the conditioning film.

The world is drowning in data. The recent explosion of web publishing, XML data, bioinformation, scientific data, image data, geographical map data, and even email communications has put a strain on our ability to manage the information contained there. In general, the influx of massive data sets for all kinds of data present a number of difficulties with storage, organization of information, and data accessibility. A primary computing challenge in these cases is how to compress the data but still allow it to be queried quickly.In real-life situations, many instances of data are highly compressible, presenting a major opportunity for space savings. In mobile applications, such savings are critical, since space and the power to access information are at a premium. In a streaming environment, where new data are being generated constantly, compression can aid in prediction as well. In the case of bioinformatics, understanding succinct representations of DNA sequences could lead to a more fundamental understanding of the nature of our own "data stream," perhaps even giving hints on secondary and tertiary structure, gene evolution, and other important topics.In this thesis, we focus our attention on the important problem of <i>compressed text indexing<\i>, where the goal is to compress a text document and allow arbitrary searching for patterns in the best possible time <i>without first decompressing the text<\i>. We develop a number of compressed data structures that either solve this problem directly, or are used as smaller components of an overall text indexing solution. Each component has a number of applications beyond text indexing as well. For each structure, we provide a theoretical study of its space usage and query performance on a suite of operations crucial to access the stored data. In each case, we relate its space usage to the <i>compressed size of the original data</i> and show that the supported operations function in near-optimal or optimal time. We also present a number of experimental results that validate our theoretical findings, showing that our methodology is competitive with the state-of-the-art. / Dissertation

Over the past few decades, the demand for digital information has increased drastically. This enormous demand poses serious difficulties on the storage and transmission bandwidth of the current technologies. One possible solution to overcome this approach is to compress the amount of information by discarding all the redundancies. In multimedia technology, various lossy compression techniques are used to compress the raw image data to facilitate storage and to fit the transmission bandwidth. In this thesis, we propose a new approach using algebraic integers to reduce the complexity of the Daubechies-4 (D4) and Daubechies-6 (D6) Lifting based Discrete Wavelet Transforms. The resulting architecture is completely integer based, which is free from the round-off error that is caused in floating point calculations. The filter coefficients of the two transforms of Daubechies family are individually converted to integers by multiplying it with value of 2x, where, x is a random value selected at a point where the quantity of losses is negligible. The wavelet coefficients are then quantized using the proposed iterative individual-subband coding algorithm. The proposed coding algorithm is adopted from the well-known Embedded Zerotree Wavelet (EZW) coding. The results obtained from simulation shows that the proposed coding algorithm proves to be much faster than its predecessor, and at the same time, produces good Peak Signal to Noise Ratio (PSNR) at very low bit rates. Finally, the two proposed transform architectures are implemented on Virtex-E Field Programmable Gate Array (FPGA) to test the hardware cost (in terms of multipliers, adders and registers) and throughput rate. From the synthesis results, we see that the proposed algorithm has low hardware cost and a high throughput rate.

Due to the fast development in 3D technology during recent decades, many approaches in 3D representation technologies have been proposed worldwide. In order to get an accurate information to render a 3D representation, more data need to be recorded compared to normal video sequence. In this case, how to find an efficient way to transmit the 3D representation data becomes an important part in the whole 3D representation technology. Recent years, many coding schemes based on the principle of encoding the depth have been proposed. Compared to the traditional multiview coding schemes, those new proposed schemes can achieve higher compression efficiency. Due to the development of depth capturing technology, the accuracy and quality of the reconstructed depth image also get improved. In this thesis we propose an efficient depth data compression scheme for 3D images. Our proposed depth data compression scheme is platelet based coding using Lagrangian optimization, quadtree decomposition and quadratic curve fitting. We study and improve the original platelet based coding scheme and achieve a compression improvement of 1-2 dB compared to the original platelet based scheme. The experimental results illustrate the improvement provided by our scheme. The quality of the reconstructed results of our proposed curve fitting based platelet coding scheme are better than that of the original scheme.

L'étude fine des fluctuations de courant dans les petites composantes électroniques est un excellent moyen de tester notre compréhension du transport électronique quantique. Lorsque la fréquence est suffisamment élevée, ce qui est mesuré en laboratoire n’est plus un courant d’électrons mais un champ électromagnétique causé par l’agitation des électrons. Faire un pont entre l’optique en terme de photons et l’électronique quantique est l’objectif dans le laboratoire de Bertrand Reulet. Ce mémoire de maîtrise traite des fluctuations de courant d’une jonction tunnel polarisée en courant et excitée avec une tension alternative dans les micro-ondes. La nouveauté dans ce projet provient du fait que les fluctuations de courant générées par la jonction tunnel ont été mesurées en phase et en quadrature avec l’excitation micro-onde envoyée sur l’échantillon. Il a été démontré qu’il est possible de faire un parallèle entre les fluctuations du courant électrique et l’optique quantique pour arriver à prédire le comportement de ces fluctuations en phase et en quadrature. De plus, la présence d’état comprimé ou «squeezé» sur l’une des quadratures du courant a été mesurée expérimentalement. Les résultats obtenus sont en parfait accord avec la théorie développée.

En soudage en phase solide, si la température peut avoir un rôle favorable, une sollicitation mécanique est également nécessaire pour s’affranchir de la couche d’oxyde recouvrant naturellement l’aluminium. Dans ce travail, on a ainsi cherché à comprendre l’importance de la sollicitation mécanique vis-à-vis de la création des jonctions métalliques. Dans ce but, 2 essais de soudabilité à froid ont été mis en place. L’essai de compression plane (CP) a pour but d’augmenter la surface à l’interface de soudage, de sorte à morceler la couche d’oxyde. Grâce à la microscopie, à une analyse par EF et à un modèle tensoriel de caractérisation de l’évolution des surfaces, les essais ont montré que, plus que l’importante déformation globale, le soudage se produit dans les zones de cisaillement maximum.Par conséquent, le second essai repose sur le cisaillement de l’interface de soudage : un tube sectionné est soumis à un effort de compression et de torsion alternée. Comme pour l’essai de CP, l’influence de divers paramètres a été étudiée. Parmi ceux-ci, l’état de surface (rugosités et propreté), l’angle de torsion (faible amplitude) et le nombre de cycles ont un rôle prépondérant. Les assemblages soudés ont ensuite été caractérisés mécaniquement et observés en microscopie (MEB-FEG, EBSD). Par rapport à l’essai de CP, on a pu constater une meilleure quantité et qualité des jonctions en compression-torsion alternée. De plus, un modèle thermodynamique a permis de conclure que les énergies mises en jeu sont trop faibles pour permettre un échauffement significatif : le soudage, sur environ 50% de l’interface en l’état actuel des choses, n’est réalisé que par des effets mécaniques locaux. / In solid-state welding, if the temperature generally has an important role (diffusion, recrystallization, etc.), a mechanical load is also necessary to override the oxide layer which naturally covers aluminium alloys. This work aims to understand the influence of the mechanical load on the formation of metallic bonds. To this end two cold weldability tests have been introduced. Firstly the plane strain channel-die compression of two cuboids sample aims to increase the surface at the welding interface in order to break up the oxide layer. Thanks to microscopy, a FEA model and a tensorial model of surfaces evolution, those results showed that, more than the important global deformation, welds were created in areas with maximum shear. Subsequently the second test aims to shear the welding interface: a tube is cut through its section and undergoes both a compression and a cyclic torsion load. As for our first weldability test, the influence of some parameters has been studied. Among them, the surface condition (roughness and cleanliness), the torsion angle (low amplitude) and the number of cycles are the most influential. Then the welded joints have been mechanically tested and microscopically observed (FEG-SEM and EBSD). In comparison with our first test, a higher quality and quantity of the joining has been showed. Moreover, a thermodynamic model concludes that the energies involved in this experimental process are too low to imply any local heating: the joining, on 50% of the welding interface as things stand, is only achieved thanks local mechanical effects.

Les fluides magnétorhéologiques (MR) sont des fluides intelligents dont la viscosité apparente peut être modifiée rapidement (<1ms) par l'application d'un champ magnétique externe. À l'aide de cette caractéristique unique, les embrayages MR permettent de moduler rapidement un couple entre deux surfaces sans contact mécanique direct. De construction simple et robuste, les embrayages MR offrent ainsi un potentiel remarquable d'innovation pour diverses applications robotiques nécessitant un contrôle rapide et une haute fiabilité, comme dans les domaines de l'automobile [10], de l'aéronautique [16] ou de l'interaction humaine [77]. À ce jour, les embrayages MR exploitent le fluide MR strictement en cisaillement pur. Dans de telles conditions, la densité de couple des embrayages est limitée par l'optimisation de la mécanique des embrayages (ex. : poids) [63] et les propriétés fondamentales des fluides MR (ex. : contrainte) [11]. Alors qu'en cisaillement pur, la contrainte des fluides MR est limitée à ∼100 kPa, des études récentes démontrent qu'elle peut être augmentée d'un ordre de grandeur (>1000 kPa) lorsque le fluide MR est soumis à une compression, avant d'être cisaillé [89]. La combinaison de la compression et du cisaillement du fluide MR pourrait ainsi décupler la densité de couple des embrayages MR, mais ce phénomène d'agrégation assistée par compression, aussi appelé squeeze-strengthening ou super-strong} (SS), est toujours très mal compris. Beaucoup d'incertitude persiste quant à l'origine exacte du phénomène [45], des conditions qui le favorisent [55] [75] et des effets qu'il engendre [31]. Dans le but ultime d'augmenter la densité de couple des embrayages MR à l'aide du phénomène SS, le présent projet de recherche vise à étudier le comportement rhéologique des fluides MR dans des conditions de compression et de cisaillement simultané afin d'en comprendre les conditions qui favorisent le phénomène d'augmentation des contraintes. Pour ce faire, un banc d'essai permettant la compression pure, le cisaillement pur et la compression-cisaillement simultanée des fluides MR est conçu et utilisé pour étudier le fluide MR lorsque soumis à des conditions de chargement typique des embrayages MR. Les résultats expérimentaux issus de cette vaste étude expérimentale permettront d'établir un lien direct entre ce phénomène et le celui de filtration, duquel un modèle prédictif sera proposé. À l'aide du modèle théorique, le phénomène SS sera étudié à l'aide de diverses compositions de fluide MR (ex. : concentration, taille des particules, viscosité) et différentes géométries de compression, ce qui permettra de valoriser le modèle pour la conception préliminaire d'embrayages MR qui exploitent le phénomène SS.