Les gaz atomiques dégénérés représentent des systèmes modèles pour étudier la superfluidité. Ils offrent la possibilité d'explorer la physique en dimensions restreintes, profondémentdifférente par rapport au cas tridimensionnel. Nous disposons d'un gaz de Bose bidimensionnel dégénéré confiné dans un potentiel très anisotrope et dont on peut changer la géométrie dynamiquement. Une déformation contrôlée du piège permet d'exciter les modes collectifs du gaz. Nous avons fait d'abord une analyse en composantes principales du gaz, et nous avons montré que ces dernières coïncident avec les modes de Bogoliubov. Nous avons ensuite effectué une étude détaillée du mode ciseaux, dont nous nous servons pour sonder le caractère superfluide du gaz, en développant une nouvelle technique d'analyse, appelée "analyse de la moyenne locale". Enfin nous avons réalisé un piège en anneau, obtenu à l'intersection d'un piège en forme de bulle et du potentiel optique d'un faisceau qui présente un noeud d'intensité au centre, la "double nappe", et nous proposons différentes protocoles de mise en rotation des atomes dans l'anneau. / Degenerate atomic gases can be a versatile tool to study superfluidity. They also offer the possibility to explore the low-dimensions physics, which is deeply different from the three dimensional case. We prepare a degenerate Bose gas in a very anisotropic trap, dynamically adjustable. A controlled deformation of the trapping potential can excite the collective modes of the trapped cloud. First we perform a « principal components analysis » of the gas and we show that the principal components coincide with the Bogoliubov modes. We then restrain our analysis on the scissors mode, which we use to probe superfluidity of the sample, by introducing a new analysis technique, called « local average analysis ». Finally I will report on the realization of a ring trap, obtained by superposing a double sheet light beam to a bubble trap, and describe the different possibilities we planned to set atoms into rotation.

Multilayer composite materials have a high tendency to interlaminar delamination when they are subjected to out-of-plane loading, because of their low-stiffness in the through-thickness (T-T) direction. The main aim of this research was to improve the interlaminar fracture toughness (IFT) of textile composites by using stitching as a T-T reinforcement technique. The intention was to provide greater delamination resistance and also to enhance the interlaminar fracture toughness between adjacent layers. In this research, E-glass 2x2 twill weave structure fabric layers and an epoxy resin were chosen as the base materials. Three different types of stitching; including the commonly-used modified lock-stitch and orthogonal-stitch (OS) geometries, the single-yarn orthogonal-stitch (SOS) and a newly-developed double-yarn orthogonal-stitch (DOS), as well as five different stitch densities were used to reinforce the multilayer preform lay-ups. The resin infusion moulding method was used to manufacture the E-glass/Epoxy 3D textile composites. The effect of stitched reinforcement on the Mode I-IFT mechanism was examined by performing double cantilever beam (DCB) tests and the Mode II-IFT mechanism by performing four-point bend end-notched flexure (4ENF) tests, respectively. Optical microscopy and scanning electron microscopy (SEM) imaging techniques were used to study the fracture surfaces of the stitched composite specimens, to assess the improvement in IFT mechanisms imparted by the stitched reinforcement used. The effect of stitching was analysed by comparing the various stitching geometries, stitch densities and the mechanical properties highlighted by the Mode I-IFT and Mode II-IFT results. It was found that the use of the novel double-yarn orthogonal-stitch (DOS) reinforcement allied with the use of high stitch densities gave the greatest improvement on both Mode I-IFT and Mode II-IFT tests. Moreover, in every case, the use of DOS and high stitch densities gave a significant improvement of 74.5% in Mode I-IFT and 18.3% for Mode II-IFT tests when compared with unstitched samples. It has been shown that the novel DOS stitch geometry yields significant benefits over established stitching techniques in respect of stitched reinforcement for laminated composite preforms. Besides this, the double column 5x5 mm stitch pattern reveals the highest delamination resistance performance among all the stitching formations tested for Mode I-IFT and II-IFT.

Cette thèse s’effectue au sein de l’université de Bordeaux. Ce projet concerne la construction en bois et en particulier la compréhension des phénomènes à l’origine des fissures dans les structures bois. L’un des objectifs étant de concevoir des méthodes efficaces de renforcement local pour les éléments de structure. Pour cela, l’étude se décompose en plusieurs étapes, la compréhension des phénomènes mis en jeu dans la création des fissures sur des bois de construction. Ce travail s’orientera sur la modélisation de fissure en mode mixte, la recherche de solution de renforcement avec compréhension fine de l’impact de types de renforts sur la propagation de la fissure. Cette étude sera accompagnée d’une campagne d’essais, afin de vérifier l’efficacité des renforcements choisis et d’identifier l’impact de l’effet d’échelle sur les modèle de prédiction. Des essais de grandes dimensions seront donc réalisés pour mieux appréhender les effets de groupes et les effets d’échelle sur du matériau d’emploi. On vise ensuite à définir des outils prédictifs de la résistance des systèmes renforcés et de moyens de contrôles pour les Plan d’Assurance Qualité. / The purpose of reinforcing assemblies and structural elements inwood is to overcome the resistance limits of the material, by transferring greaterefforts in areas which can lead to premature cracking in structures. The reinforcementsused can be made of steel, composite materials or wood. Their hook can bemechanical (screwed bodies) or by adhesion (structural bonding like glued-in rodsfor example). In both cases, the transfer of solicitations remains poorly known, andthe effect of the beginning and the deflection of crack are not well apprehended. Inengineering techniques, the wood resistance in the reinforced area is neglected, whichis in line with the precautionary principle. Currently, the scientific investigations areinterested in the resistance of those kind of techniques without considering the interactionsbetween the quasi-brittle behavior of the wood and the reinforcementswhich govern the gain in mechanical performance. However, these solutions can leadto a failure caused by the progressive splitting of the wood and the anchor loss ofthe reinforcement. So it seems accurate to propose predictions of the short-termstrength for splitting of reinforced and unreinforced beams, which can be used tofurther exploration of the long-term failure mechanism. That is why, in this study, aglobal prediction model of the ultimate strength of structural components subjectedto splitting, reinforced and unreinforced ones, was developed. It considers the quasibrittlebehavior of the wood and crack propagation in mixed mode, using a mixinglaw established on the R-curves. The relevance of this modeling was then comparedto the current dimensioning methods of the Eurocodes 5, for notched beams, withexperimental campaigns conducted at different scales.

O átrio esquerdo (AE) pode aumentar de tamanho e massa por sobrecarga de pressão e volume em várias doenças cardíacas, a exemplo da degeneração da valva mitral. O tamanho do AE é de especial interesse na avaliação da gravidade da doença, uma vez que o grau de aumento será um dos parâmetros para a instituição da terapia. A ecocardiografia é o método padrão para a avaliação não invasiva do paciente cardiopata e sempre inclui a mensuração do tamanho do AE. O modo-M convencional tem sido usado para tal avaliação, contudo, o mesmo tem suas limitações, devido à dificuldade em incluir a porção mais ampla do AE, resultando em um diâmetro e índice AE:AO subestimados. No modo bidimensional o AE pode ser mensurado em sua maior amplitude, resultando em uma medida mais acurada. Assim sendo, o objetivo deste estudo foi comparar os dois métodos, utilizando-se de 40 cães adultos sadios, com idade variando de 1,5 a 7 anos. No modo-M, o AE e a aorta (AO) foram medidos conforme normas da American Society of Echocardiography, no corte longitudinal para-esternal direito, e no modo bidimensional realizaram-se medidas lineares em pontos específicos e em momentos estabelecidos do ciclo cardíaco, no corte transverso para-esternal direito. Estabeleceu-se um índice para cada método, dividindo-se o diâmetro do AE com a AO. Observou-se que a diferença de diâmetro do AE no modo bidimensional (AEB) e do AE no modo-M foi estatisticamente significante (p < 0,001). O mesmo ocorreu com o índice AEB:AOB quando comparado ao índice AEM:AOM, sendo que a média do AEB:AOB = 1,379±0,130; I.C. 95%= 1,337-1,422 e a média do AEM:AOM = 1,067±0,064, I.C. 95%= 1,046-1,088. Observou-se correlação alta entre as medidas do AE, nos dois modos, com superfície de área corpórea e peso (coeficiente de correlação = 0,882-0,896). Ocorreu correlação alta também entre as medidas de AE dos sexos masculino e feminino, pelos dois métodos (p=0,003 e coeficiente de correlação = 0,725-0,732). Com relação aos índices, não houve correlação entre os mesmos e a superfície de área e o peso, podendo-se dizer que são, portanto, índices independentes de peso. O modo bidimensional oferece a possibilidade de aferição do AE em sua maior amplitude, superando assim o modo-M convencional. / The left atrium (LA) can become enlarged in size and mass attributable to both pressure and volume overload in various cardiac diseases, an example is the mitral valve degeneration. The size of LA is of special interest for clinical assessment of severity of the disease, once the degree of enlargement will be one of the parameters for therapy institution. The echocardiography is the standard method of noninvasive evaluation of the cardiac patient and often involves the LA size. The M-mode has been used to this evaluation, however it has inherent limitations, due to the difficulty in including the largest portion of the LA, underestimating the LA diameter and LA:AO index. In the two-dimensional (2D) mode, the LA can be measured at its largest portion and it is likely to be more accurate. The purpose of this study was to compare both methods, using 40 healthy adult dogs, and ages between 1,5 and 7 years old. In the M-mode, the LA and the aorta (AO) was measured according to the guidelines from the American Society of Echocardiography, using a right long-axis view and in the 2D-mode, linear measurements were made at specific time and points of the cardiac cycle, using a right short-axis view. LA:AO ratios were established for each method. The difference between the LA diameter in the 2D-mode (LAB) and in the M-mode (LAM) was significant (p < 0,001). The same has occured with the LAB:AOB index when it was compared with the LAM:AOM ratio. The LAB:AOB index was 1,379±0,130; C.I. 95%= 1,337-1,422 and the LAM:AOM index was 1,067±0,064, C.I. 95%= 1,046-1,088. It was observed high association between LA measurements, in both methods, with body weight and body surface area (correlation coefficient = 0,882-0,896) and also a high correlation between the LA in female and male, in both methods (p=0,003 e correlation coefficient = 0,725-0,732). There was no association between both indices with body weight and body surface area, which provides a body weight - independent measurement of LA size. The 2D - mode offers more accurate LA measurement , so it overcomes the M- mode.

A Na, K-ATPase (NKA) é uma proteína de membrana encontrada em organismos eucariotos multicelulares cuja atividade e funções já são amplamente discutidas na literatura. Sua unidade funcional corresponde a um heterodímero formado por duas subunidades , com regiões transmembrana. Espécies multiméricas como dímeros e tetrâmeros dessa enzima também são conhecidos por exercer atividade enzimática. As interações lipídio-proteína são intrínsecas para a NKA, por tal motivo, proteolipossomos constituídos de DPPC e DPPC:DPPE foram preparados por co-solubilização. Como controle, lipossomos de mesma composição foram produzidos por extrusão e/ou sonicação. Para as imagens de AFM, as amostras foram fixadas com glutaraldeído, para proteção mecânica e contra desidratação das vesículas. Para lipossomos de DPPC as imagens topográficas de AFM das vesículas apresentaram formato oval, superfície perfeitamente lisa e diâmetro médio de 151 + 46 nm, enquanto as vesículas de composição DPPC:DPPE, apesar de lisas, tiveram cantos pontiagudos e diâmetro médio de 98 + 28 nm. Imagens de fase de ambas as composições não apresentaram qualquer indicativo de diferenças na composição química, provavelmente devido à natureza de carga neutra dos dois fosfolipídios. As imagens de fase por AFM para os proteolipossomos tanto de DPPC-NKA, quanto DPPC:DPPE-NKA, revelaram resultados inéditos na literatura, onde a inserção da NKA aparece como nítidas regiões transições de fase de composição química distinta quando comparadas com os lipossomos. No entanto, as mudanças de fase são diferentes entre as composições estudadas, aparecendo como manchas escuras circulares para DPPC-NKA e mais visíveis como interstícios brilhantes para composição de DPPC:DPPE-NKA. As vesículas de DPPC-NKA apresentaram diâmetro médio de 390 + 326 nm e, nas imagens de topografia tridimensionais, protusões de 38 a 115 nm correspondentes às regiões de mudanças de fase, que, indicaram o diâmetro dos microdomínios relacionados à proteína. Já nas imagens para DPPC:DPPE-NKA o diâmetro médio dos proteolipossomos foi de 189 + 156 nm, e as protusões apareceram entre os interstícios, variando de 20 a 66 nm. O estudo de DSC dos lipossomos revelou que a concentração de glutaraldeído nas condições das análises de AFM, em torno de 5% (v/v), afetam as características físico-químicas para as composições com DPPE. A AFM foi eficiente para confirmar a reinserção da NKA em proteolipossomos pelas imagens de fase, e, para medir o diâmetro dos microdomínios pelas imagens de topografia. / Na, K-ATPase (NKA) is a membrane protein present in eukaryotic multicellular organisms. Its functions and activity are already widely described in the literature. Its minimal functional structure is a heterodimer of two main subunits , with transmembrane domains. However, dimers and tetramers of the enzyme are also known to have enzymatic activity. Since there are intrinsic lipid-protein interactions, NKA proteoliposomes composed of DPPC and DPPC:DPPE (1:1 molar ratio) were prepared by the co-solubilization method and liposomes of the same compositions were obtained by extrusion and/or sonication to be used as control. The samples to the AFM study were prepared using glutaraldehyde to protect the vesicles from mechanical shocks and dehydration. Liposomes composed of DPPC and DPPC:DPPE (1:1 molar ratio) were prepared by extrusion and sonication, respectively, as control. The topographical images for DPPC liposomes showed vesicles with an oval shape and smoothed surfaces with a mean diameter of 151 + 46 nm. DPPC:DPPE vesicles also presented smoothed surfaces, but with pointed corners and mean diameter of 98 + 28 nm. Phase images for both lipid compositions showed no differences in chemical composition. For DPPC:DPPE samples, this can be explained by the neutral net charge of both lipids. The proteoliposomes observed in the AFM phase images showed darker and large circular spots in the vesicles. These spots represent delays in the phase oscillation of the AFM probe and are associated with different chemical composition. The phase changes showed the reconstitution of the NKA in the proteoliposomes. When compared with topographical images, this spots matched protrusions. The mean diameter of DPPC-NKA proteoliposomes determined by AFM was 390 + 326 nm. In the three-dimensional topographical images of composition, protrusions from 38 to 115 nm near the areas of different phases indicate the diameters of the NKA microdomains. The phase changes for DPPC:DPPE-NKA appeared as bright interstices with the protrusions of the topographical images in between them. The size of these protrusions ranged from 20 to 66 nm and the mean diameter of the proteoliposomes was 189 + 156 nm. The DSC liposomes data showed that the glutaraldehyde concentration used in the AFM analysis affect the physical chemistry properties of the samples with DPPE. AFM proved to be an efficient method to confirm the reconstitution of into proteoliposomes with phase images and to determine the diameter of the protein microdomains with the topographical images.

<p>This thesis is an approach to improve a two-mode hybrid electric vehicle, which is currently under development by GM, with respect to fuel consumption. The study is not only restricted to the specific two-mode HEV but also presents results regarding parallel as well as serial HEV’s. GM whishes to verify if the online-based controller in the prototype vehicle utilizes the most of the HEV ability and if there is more potential to lower the fuel consumption. The purpose is that the results and conclusions from this work are to be implemented in the controller to further improve the vehicle’s performance. To analyze the behavior of the two-mode HEV and to see where improvements can be made, models of its driveline and components are developed with a focuson losses and efficiency. The models are implemented in MATLAB together with an optimization algorithm based on Dynamic Programming. The models are validated against data retrieved from the prototype vehicle and various cases with different inputs is set up and optimized over the NEDC cycle. Compensation for cold starts and NOx emissions are also implemented in the final model. Deliberate simplifications are made regarding the modeling of the power split’s functionality due to the limited amount of time available for this thesis. The optimizations show that there is potential to lower the fuel consumptionfor the two-mode HEV. The results are further analyzed and the behavior of the engine, motors/generators and battery are compared with recorded data from a prototype vehicle and summarized to a list of suggestions to improve fuel economy.</p>

<p>Switch Mode Power Supplies are very important components in present day electronics and have continued to thrive and grow over the past 25 years. This thesis looks inside how the SMPS have evolved over the passage of years with special emphasis to the Synchronous Buck Converter. It also discusses why there is a strong potential to further the study related to designs based around a Synchronous Buck Converter for portable applications. The main objective of the thesis is to look into the controller design for minimizing size, enhancing efficiency and reliability of power converters in portable electronic equipment such as mobile phones and PDAs. The thesis aims to achieve this using a 90 nm process with an input voltage of 1.55V and an output of 1V with a power dissipation of 200mW.</p>

<p>Power-amplifier efficiency is a significant issue for the overall efficiency of most wireless system. Therefore, currently there are different kind of Switched mode power amplifiers are developed which are showing very high efficiency also at higher frequencies but all of these amplifiers are subjected to drive with the constant envelope signals. Whereas, for the increasing demand of high data rate transmissions in wireless communication there are some new modulation schemes are introduced and which are generating no more a constant envelope signal but a high peak to average power signal. Therefore, recently a new technique is proposed called the burst mode operation for operating the switched mode power amplifiers efficiently while driven by a high peak to average power signal.</p><p> </p><p>The purpose of this master thesis work was to review the theory of this burst mode operation and some basic investigations of this theory on switched mode power amplifiers were performed in simulation environments. The amplifiers of class D, inverse D, DE and J are studied. The thesis work was mainly carried out by ADS and partly in MATLAB SIMULINK environment. Since this burst mode operation is a completely new technique therefore a new Harmonic balance simulation setups in ADS and Microwave Office are developed to generate the RF burst signals.</p><p> </p><p>A Class J amplifier based on LDMOS technique is measured by a 16 carrier multi-tone signal having peak to average power ratio of 7 dB and achieved the drain efficiency of 50% with -30 dBc linearity at 946 MHz.</p><p> </p><p> </p>

Switch Mode Power Supplies are very important components in present day electronics and have continued to thrive and grow over the past 25 years. This thesis looks inside how the SMPS have evolved over the passage of years with special emphasis to the Synchronous Buck Converter. It also discusses why there is a strong potential to further the study related to designs based around a Synchronous Buck Converter for portable applications. The main objective of the thesis is to look into the controller design for minimizing size, enhancing efficiency and reliability of power converters in portable electronic equipment such as mobile phones and PDAs. The thesis aims to achieve this using a 90 nm process with an input voltage of 1.55V and an output of 1V with a power dissipation of 200mW.

The primary focus of this thesis is to present a simple and practical implementation of an optimal-time response controller for multiphase interleaved dc-dc SMPS. This novel solution enables equal current sharing between phases not only in steady-state, but also during load transients, as well as bump-less transition between those two states. A digital voltage loop and multiple analog peak current programmed mode current loops are combined to implement a capacitor charge balance control algorithm with fairly simple hardware. This algorithm provides recovery from a disturbance in a single on-off switching action, which is performed in virtually the fastest possible time. The hybrid interface between the loops is provided through a structure combining a sample-and-hold circuit and a relatively slow successive-approximation DAC that provides control signals for all the loops in the system. Furthermore, for operation under light load conditions, the controller automatically switches into simply implemented pulse-frequency mode of operation.