Une structure en béton doit assurer des fonctions structurales qui vont au delà de la simple résistance. Dans ce cadre, la fissuration du béton armé joue un rôle primordial sur la durabilité, l'étanchéité et même la sûreté des structures. La structure poreuse du béton rend naturellement possible la pénétration au cours du temps d'espèces délétères. En outre, sous l'effet des chargements mécaniques et des conditions environnementales au sens large, le béton se fissure. Les fissures constituent, elles aussi, des voies préférentielles pour la pénétration de fluides ou d'agents agressifs et ajoutent de manière significative leur contribution à la dégradation des performances structurelles. Dans la thèse une stratégie de modélisation macroscopique probabiliste du couplage entre fissuration et transferts de fluides dans les structures en béton est présentée. Le béton est modélisé comme un milieu poreux saturé d'eau tandis que la fissuration (mécanique) est modélisée au travers d'une approche numérique probabiliste tenant compte de l'hétérogénéité naturelle du matériau et des effets d'échelle qu'elle induit. L'hypothèse physique de base du modèle de fissuration est que chaque élément fini peut être considéré comme représentatif d'un volume de matière hétérogène dont le comportement est géré par son degré d'hétérogénéité, défini comme le rapport entre le volume élémentaire et un volume représentatif de l'hétérogénéité du matériau. Dans la formulation développée, les propriétés mécaniques du matériau sont considérées comme des variables aléatoires (non corrélés) distribuées dans les éléments du maillage selon des distributions statistiques validées expérimentalement. Une approche par analyse inverse permet d'accéder aux paramètres de fonctions de distribution qui, selon les hypothèses du modèle, varient en fonction de la dimension des éléments finis. Le couplage fissuration-transfert est traité de manière faible, sous l'hypothèse d'absence d'interaction entre les deux processus (à savoir que la fissuration de l'élément fini, d'origine mécanique, induit une variation locale de sa perméabilité). L'utilisation d'une loi de Poiseuille modifiée et adaptée expérimentalement selon un protocole développé dans le cadre de la thèse permet de mettre en relation une telle variation avec l'ouverture de fissure et de prendre en compte, de manière macroscopique, les principales causes d'écart entre l'écoulement idéalisé, représenté par la loi de Pouiselle, et l'écoulement dans des fissures réelles. Une approche de type Monte-Carlo permet de valider les résultats des simulations mécaniques et hydriques. Les capacités de la stratégie de modélisation proposée en termes de prédiction des débits d'eau en milieu fissuré sont explorées au travers de la simulation d'essais de perméabilité sous charge sur des éprouvettes cylindriques soumises à du fendage. Ces essais sont utilisés dans le cadre du protocole expérimentale. Une première validation à l'échelle d'un élément structurel multifissuré est presentée. Elle consiste en la simulation d'un essai (récemment proposé dans la littérature) developpé pour l'étude de l'impact de la fissuration sur les propriétés de transfert de tirants en béton armé / Concrete durability is strongly affected by the flow of fluids, gas and pollutants in its porous matrix. The presence of cracks weakens the resistance of concrete porous matrix and constitutes preferential flow paths for aggressive components. In the thesis, a probabilistic numerical modeling strategy for modeling fluids transfers in cracked concrete structures is presented. The concrete is modeled in the framework of water saturated porous media. Its (mechanical) cracking is modeled by means of a macroscopic probabilistic approach, explicitly taking into account material heterogeneity as well as size effects. The main assumption of the model, developed in the frame of the the Finite Element Method, is to consider a finite element volume as a volume of heterogeneous material and to assume that physical mechanisms influencing the cracking processes remain the same whatever the scale of observation. At the scale of the finite element, mechanical properties are then functions of its own volume. To describe the heterogeneity of the material, these mechanical properties are consider as uncorrelated random variables distributed over the finite element mesh. Characteristics of statistical distribution laws are directly depending on the degree of heterogeneity of the finite element (the ratio between its volume and the volume of the coarsest aggregate) and of the quality of the cement paste. An inverse analysis approach allows to find their parameters as functions of the elementary volume. A weak coupling between cracking and fluid transfers is considered, under the assumption of no interaction between the two processes (i.e. the mechanically produced cracking of a finite element induce a local variation of its permeability tensor). An experimentally adapted Pouiseuille law, based on an original experimental protocol, allows to relate this permeability variation to the crack aperture and to macroscopically take into account the influence of crack roughness, aperture variation and tortuosity. A Monte-Carlo like approach is used in order to statistically validate mechanical and hydraulic simulations. The coupling strategy is validated in two phases, both at the scale of a laboratory specimen and at the scale of a multi-cracked structural element

: Les travaux présentés dans cette thèse traitent du contrôle de systèmes dynamiques soumis à des excitations harmoniques et transitoires en utilisant des absorbeurs de type Nonlinear Energy Sink (NES). Plusieurs aspects ont été développés : la conception et la réalisation d'un nouveau design pour le NES cubique, l'étude de la location et du transfert irréversible d'énergie sur un NES bistable et le développement d'un critère de conception pour un NES à Vibro-Impact (VI). Dans un premier temps, un critère de conception est proposé pour le NES à raideur cubique. Le design proposé est basé sur des ressorts coniques ou des ressorts à pas variable. Un mécanisme à raideur négative est aussi introduit pour supprimer la partie linéaire et avoir une raideur cubique pure. Dans un deuxième temps, le concept du NES est validé expérimentalement par des essais statiques et des essais dynamiques. Une analyse de sensibilité est aussi menée sur la longueur des ressorts précontraints, elle dénote parfois un état bistable de l'oscillateur. Ensuite, le NES bistable ainsi obtenu est étudié plus en détail. Ce type d'absorbeur s'avère être très robuste pour différents types d’excitation. Des études expérimentales sont aussi menées afin d'explorer le comportement dynamique. Enfin, un critère de conception est proposé pour le NES à Vibro-Impact. Des calculs analytiques détaillés sont proposés pour contrôler les vibrations sous différentes excitations. L'étude expérimentale montre une bonne cohérence avec les résultats théoriques. / The work presented in this thesis deals with the passive control of dynamics systems subjected to harmonic and transient excitations using a Nonlinear Energy Sink (NES). Several research aspects have been developed: design theory and experimental study of a novel NES, efficient Targeted Energy Transfer (TET) of bistable NES and design criteria for optimally tuned Vibro-Impact (VI) NES. Firstly, a design criterion intended to provide optimal nonlinear stiffness is proposed. Then a novel design of NES system yielding cubic stiffness with conical springs or variable pitch springs and negative stiffness mechanism is developed. Secondly, the experimental procedures for static and dynamic test are presented and applied to validate the concept of NES system. Then a sensitivity analysis is performed with respect to the pre-compressed length of springs. Thirdly, the optimal design of the above device with negative stiffness (termed as bistable NES) is studied. This type of NES is proved to work robustly for different types of excitation, and experimental study of semi-active control are explored. Finally, design criteria for optimally tuned VI NES are studied. Detailed analytical calculations of clearance to control the vibration under different excitations are proposed. A good correspondence between theoretical and experimental results is observed.

Este trabalho tem como principal objetivo o desenvolvimento de um método numérico para simulação das grandes escalas de escoamentos turbulentos tridimensionais utilizando uma modelagem de turbulência baseada em filtragem temporal (denominada TLES - Temporal Large Eddy Simulation). O método desenvolvido combina discretizações temporais com ordem de mínima precisão 2 (Adams-Bashforth, QUICK, Runge-Kutta), um método de projeção de ordem 2, com discretizações espaciais também de ordem 2 obtidas pelo método de volumes finitos. Esta metodologia foi empregada na simulação de problemas teste turbulentos como o canal e a cavidade impulsionada, sendo este último resultado simulado pela primeira vez com modelagem TLES. Os resultados mostram uma excelente concordância quando comparado com resultados de simulações diretas (DNS) e dados experimentais, superando resultados clássicos obtidos com formulação LES com filtragem espacial. / The main objective of this work is to develop a numerical method for large eddy simulation of tridimensional turbulent flows using a model based on temporal filtering (TLES - Temporal Large Eddy Simulation). The developed method combines at least 2nd order temporal discretizations (Adams-Bashforth, QUICK, Runge-Kutta), a 2nd order projection method, and 2nd order spatial discretizations obtained by the finite volume method. This methodology was employed to the simulation of turbulent benchmark problems such as channel and lid-driven cavity flows. The latter is simulated for the first time using a TLES turbulence modelling. Results show excellent agreement when compared to Direct Numerical Simulations (DNS) and experimental data, with better results than classical results produced by standard LES formulation with spatial filtering.

L’Optimisation Topologique (OT) est un sujet en plein essor qui suscite l’intérêt de nombreux chercheurs depuis ces deux dernières décennies dans le domaine de l’électromagnétisme. L’OT représente une méthode très attrayante et originale car elle permet de trouver des structures innovantes sans aucun a priori. Ce travail de thèse est orienté vers l’OT des dispositifs électromagnétiques en approfondissant plusieurs aspects du sujet. Tout d’abord, un outil d’OT est développé et testé, à partir des outils existant au L2EP. En effet, l’OT requiert un outil d’éléments finis et un outil d’optimisation devant être couplés. Une méthodologie originale d’OT fondée sur les principes de la Méthode de Densité est développée et testée. Un cas test académique est utilisé afin de tester et valider le couplage des outils et la méthodologie. Une approche visant à prendre en compte le comportement non-linéaire des matériaux ferromagnétiques avec nos outils OT est également mise en place. Ensuite, la méthode est appliquée afin d’optimiser un électroaimant en 3 dimensions, représentant un cas test proche de la réalité. Ce cas test permet de comparer les résultats avec un comportement linéaire et non-linéaire des matériaux. Diverses topologies sont présentées, par rapport aux différentes formulations du problème. Par la suite, la méthodologie est appliquée à un dispositif électromagnétique plus complexe : une Génératrice Synchrone à Pôles Saillants. Cet exemple nous permet de voir comment la définition du problème d’optimisation peut grandement affecter les résultats d’OT. Quelques topologies sont présentées, et leur faisabilité est analysée / Topology Optimisation (TO) is a fast growing topic that has been sparking the interest of many researchers for the past two decades in the electromagnetic community. Its attractiveness lies in the originality of finding innovative structures without any layout a priori. This thesis work is oriented towards the TO of electromagnetic devices by elaborating on various aspects of the subject. First of all, a tool for TO is developed and tested, based on the ‘home-made’ tools available at the L2EP. As TO requires a FE and an optimisation tool working together, a coupling is done using both. Furthermore, a TO methodology is developed and tested, based on the Density Method. An academic cubic test case is used to carry out all the tests, and validate the tools and methodology. An approach is also developed to consider the nonlinear behaviour of the ferromagnetic materials with our TO tools. Afterwards, the methodology is applied to a 3D electromagnet, which represents a more real test case. This test case also serves to compare the results with linear and nonlinear behaviour of the materials used. Various topologies are presented, for different problem formulations. Subsequently, the methodology is applied to a more complex electromagnetic device: a Salient Pole Synchronous Generator. This example allows us to see how the problem definition can largely affect TO results. Some topologies are presented and their viability is discussed

Made available in DSpace on 2016-03-22T17:26:24Z (GMT). No. of bitstreams: 1 Wagner Guimaraes Al-Alam.pdf: 2995290 bytes, checksum: 9902eafe02c0b5318a99f1e796dc399f (MD5) Previous issue date: 2010-01-15 / Companies working with bulk materials have appropriate locations for storage during the development of the production and storage of the final product, known as warehouses or storehouses. The values of stocks need to be periodically validated by comparing the control of receipts the and the physical situation (removal of the volume stored in the company). In this context, the calculation of physical inventory as the volume of bulk present in the warehouses is usually done manually with low credibility and prone to errors. The current audit procedures on the contents of warehouses involve inaccurate estimates, and often require emptying the warehouse. Considering the use of technologies which enable the electronic measurement of distances, angles, and automatic controls on actuators enabling mechanical movements on the supporting structures, we sought to develop a system capable of providing both computing solutions, and technology for the problem of calculation of irregular relief (products stocked in warehouses). The Automated Auditing Warehouse SisA3 intends to make this process automatic, fast and precise, without the need for emptying warehouses or having contact the products. To achieve this goal, we developed an integrated system composed of: (i) a scanner equipment, consoling the hybrid prototype of hardware and software called DigSisA3, in order to the measurement of points of relief non-uniform, formed by the products in stock, and (ii) a method for calculating the volume iCone, which combines techniques of scientific visualization, numerical interpolation points and iterative calculation of volume. The parallelization of the prototype iCone was also developed in order to satisfy the test of agility and performance of the method iCone in the audit process. The development for multiprocessor, multi-core, and distributed architectures was done over the DGM (Geometric Distributed Machine), which provides the formalities to ensure creation, management and application processing parallel and / or distributed scientific computing, with emphasis on the exploitation of data parallelism and synchronization steps. The prototype of software iCone was functionally validated, including analysis of error in the method. The analysis of performance in the prototype p-iCone showed satisfactory results. The development of this work strengthens the system SisA3, enabling automatic and reliable measurement of inventories, including broad market application / Empresas que trabalham com produtos a granel possuem locais para estocagem, durante o desenvolvimento do processo produtivo e no armazenamento do produto final, denominados armaz´ens ou silos. Os valores dos estoques devem ser validados periodicamente atrav´es da comparac¸ ao dos estoques fiscal (controle das notas fiscais) e f´ısico (levantamento do volume estocado na empresa). Neste contexto, o c´alculo do estoque f´ısico, ou seja, o volume de gran´eis presentes nos armaz´ens, ´e geralmente efetuado de forma manual e com baixa credibilidade, desta forma com propens ao a erros. Os atuais processos de auditoria no conte´udo de silos, al´em de envolverem estimativas inexatas, est ao frequentemente baseados no esvaziamento do silo. Considerando o uso de tecnologias que viabilizam a medic¸ ao eletr onica de dist ancias, angulos, e controles autom´aticos sobre atuadores que possibilitam movimentos mec anicos sobre estruturas de suporte, buscou-se o desenvolvimento de um sistema capaz de prover tanto soluc¸ oes computacionais, quanto tecnol´ogicas para o problema de c´alculo do volume de relevos irregulares, no caso dos produtos estocados nos armaz´ens. O Sistema Automatizado de Auditoria em Armaz´ens (SisA3) pretende tornar este processo autom´atico, r´apido e preciso, sem a necessidade de esvaziamento ou contato com os produtos. Para alcanc¸ar este objetivo, tem-se um sistema integrado composto de: (i) um equipamento digitalizador, consolidando o prot´otipo h´ıbrido de hardware e software denominado Dig-SisA3 , para a medic¸ ao de pontos do relevo n ao-uniforme, formado pelos produtos estocados; e (ii) m´etodo para o c´alculo do volume (iCone), que combina t´ecnicas de visualizac¸ ao cient´ıfica, interpolac¸ ao num´erica de pontos e c´alculo iterativo de volume. Al´em disto, introduz-se a paralelizac¸ ao do prot´otipo iCone, para diminuir o tempo da obtenc¸ ao dos resultados do m´etodo iCone no processo de auditoria. A an´alise sobre as perspectivas em arquiteturas multiprocessadas, multi-core e paralela distribu´ıda, utiliza o ambiente D-GM (Distributed Geometric Machine), a qual prov e os formalismos para garantir criac¸ ao, gerenciamento e processamento de aplicac¸ oes paralelas e/ou distribu´ıdas da computac¸ ao cient´ıfica, com enfase na explorac¸ ao do paralelismo de dados e nas etapas de sincronizac¸ oes. O prot´otipo de software iCone apresenta-se funcionalmente validado, incluindo an´alise de erro na execuc¸ ao do m´etodo. As an´alises de desempenho no prot´otipo p-iCone apresentaram resultados satisfat´orios. O desenvolvimento deste trabalho consolida o sistema SisA3, viabilizando aferic¸ ao autom´atica e confi´avel de estoques, incluindo ampla aplicac¸ ao no mercado

Submitted by Alan Rodrigo de Sales null (alanestado@hotmail.com) on 2017-01-30T19:31:15Z No. of bitstreams: 1 Mestrado Alan Sales.pdf: 3094814 bytes, checksum: 40ab5a77d5ee1153c2e541c020d3ca6c (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-02-03T16:06:14Z (GMT) No. of bitstreams: 1 sales_ar_me_bauru.pdf: 3094814 bytes, checksum: 40ab5a77d5ee1153c2e541c020d3ca6c (MD5) / Made available in DSpace on 2017-02-03T16:06:14Z (GMT). No. of bitstreams: 1 sales_ar_me_bauru.pdf: 3094814 bytes, checksum: 40ab5a77d5ee1153c2e541c020d3ca6c (MD5) Previous issue date: 2016-12-09 / A aplicação da mínima quantidade de lubrificante (MQL) na usinagem dos metais começaram a ser estudados como alternativa para reduzir o uso dos fluidos de corte, para poder atingir uma produção mais limpa e menos prejudicial ao meio ambiente e aos trabalhadores, na retificação, apesar de ser considerada uma técnica inovadora no aspecto ambiental, sua aplicação é restrita devido à geração excessiva de calor e ao entupimento dos poros do rebolo causado pelos cavacos, e isto prejudica a qualidade final do produto e aumenta o desgaste da ferramenta. Esta pesquisa buscou aprimorar o uso do MQL utilizando óleo solúvel sintético da Quimatic Tapimatic ME-2. Além de usar o jato com a mistura ar e óleo e proporções de água injetado na interface rebolo-peça à alta velocidade um jato de ar comprimido, foi utilizado na superfície de corte do rebolo para minimizar o empastamento do rebolo gerado durante o processo de usinagem pela mistura formada pelo óleo do MQL mais os cavacos. Foram realizados ensaios na retificação cilíndrica externa de mergulho do aço ABNT 4340, temperado e revenido com dureza média de 54 HRC, usando rebolo de nitreto de boro cúbico (CBN) com ligante vitrificado. Os métodos de lubri-refrigeração propostos foram o convencional com fluido em abundância e o MQL (sem limpeza da superfície de corte do rebolo) e MQL (com a limpeza, utilizando o ângulo de incidência do ar comprimido na superfície de corte do rebolo fixo a 30 graus). Este ângulo foi escolhido por ser a melhor condição mostrada nos trabalhos de outros autores. Consideraram-se as variáveis de saída do processo: rugosidade, desgaste diametral do rebolo, circularidade, além de análises metalográficas e medições de microdureza da superfície retificada para verificação de danos térmicos; de forma a analisar a viabilidade da substituição do tradicional método de aplicação dos fluidos em abundância pelo MQL com a limpeza. Os resultados mostraram a possibilidade de implementação da técnica da limpeza do rebolo como um aprimoramento tecnológico da mínima quantidade de lubrificante na retificação, reduzindo o consumo dos fluidos de corte. A técnica MQL com limpeza para um ângulo específico de incidência do ar comprimido mostrou-se extremamente eficiente com a obtenção de melhor acabamento superficial e dimensional, além de menor desgaste da ferramenta abrasiva e isenção de danos térmicos, quando comparada com os métodos convencionais sem a limpeza do rebolo. / The application of minimum quantity of lubricant (MQL) on machining of metals has emerged as an alternative to reduce the abundance of cutting fluids and then achieve a cleaner production. In grinding, although considered a breakthrough technique in the environmental aspect, its application is restricted due to excessive generation of heat and grinding wheel loading caused by the chips, damaging the final product quality and increasing tool wear. The objective of this research was to improve the MQL technique synthetic soluble oil Quimatic Tapmatic ME-2 using beyond the jet with air mixture and oil and water proportions using an additional jet of compressed air to clean the clogged pores of the wheel. Grinding wheel in tests were performed in cylindrical plunge grinding of the ABNT 4340 steel, quenched and tempered (54 HRC), with a vitrified cubic boron nitride (CBN). The suggested methods of lubrication were conventional (abundant fluid), MQL (that without the use of air jet to cleaning the wheel) and MQL plus cleaning system using the angle of incidence of the compressed air on the cutting surface of the grinding wheel fixed to 30 degrees. Other autors chose This angle to be the best condition shown in the works. This performance was evaluated based on an analysis of the process output variables: roughness, diametric wear of the grinding, roundness, and metallographic analysis plus microhardness measurements of the grounded surface to verify thermal damage incidence. The results showed the possibility of implementing the technique of cleaning as a technological enhancement to minimum quantity of lubricant in the grinding, reducing the use of cutting fluids. The technique MQL plus cleaning system, in a specific incident angle of the compressed air was extremely efficient, resulting in better surface finish, reduced tool wear and free of thermal damage when compared with conventional methods without cleaning of the wheel.

Depuis l'invention de l'automobile à la fin du 19eme siècle, la taille du parc ainsi que l'importance du trafic routier n'ont cessées d'augmenter. Ceci a malheureusement été suivi par l'augmentation constante du Nombre d'accidents routiers. Un grand nombre d'études et notamment un rapport fourni par l'Organisation Mondiale de la Santé, a présenté un état alarmant du nombre de blessés et de décès liés aux accidents routiers. Afin de réduire ces chiffres, une solution réside dans le Développement de systèmes d'aide à la conduite qui ont pour but d'assister le conducteur dans sa tâche de conduite. La recherche dans le domaine des aides à la conduite s'est montrée très dynamique et productive durant les vingt dernières années puisque des systèmes tels que l'antiblocage de sécurité (ABS), le programme de stabilité électronique (ESP), le régulateur de vitesse intelligent (ACC), l'assistant aux manœuvres de parking (PMA), les phares orientables (DBL), etc. sont maintenant commercialisés et acceptés par la majorité des conducteurs. Cependant, si ces systèmes ont permis d'améliorer la sécurité des conducteurs, de nombreuses pistes sont encore à explorer. En effet, les systèmes d'aide à la conduite existants ont un comportement microscopique, en d'autres termes ils se focalisent uniquement sur la tâche qu'ils ont à effectuer. Partant du principe que la collaboration entre toutes ces aides à la conduite est plus efficace que leur utilisation en parallèle, une approche globale d'aide à la conduite devient nécessaire. Ceci se traduit par la nécessité de développer une nouvelle génération d'aide à la conduite, prenant en compte d'avantage d'informations et de contraintes liées au véhicule, au conducteur et à son environnement. [...] / Since the origin of the automotive at the end of the 19th century, the traffic flow is subject to a constant increase and, unfortunately, involves a constant augmentation of road accidents. Research studies such as the one performed by the World Health Organization, show alarming results about the number of injuries and fatalities due to these accidents. To reduce these figures, a solution lies in the development of Advanced Driver Assistance Systems (ADAS) which purpose is to help the Driver in his driving task. This research topic has been shown to be very dynamic and productive during the last decades. Indeed, several systems such as Anti-lock Braking System (ABS), Electronic Stability Program (ESP), Adaptive Cruise Control (ACC), Parking Manoeuvre Assistant (PMA), Dynamic Bending Light (DBL), etc. are yet market available and their benefits are now recognized by most of the drivers. This first generation of ADAS are usually designed to perform a specific task in the Controller/Vehicle/Environment framework and thus requires only microscopic information, so requires sensors which are only giving local information about an element of the Vehicle or of its Environment. On the opposite, the next ADAS generation will have to consider more aspects, i.e. information and constraints about of the Vehicle and its Environment. Indeed, as they are designed to perform more complex tasks, they need a global view about the road context and the Vehicle configuration. For example, longitudinal control requires information about the road configuration (straight line, bend, etc.) and about the eventual presence of other road users (vehicles, trucks, etc.) to determine the best reference speed. [...]

<p>Cellulose ethers and polyethylene glycols are used in drug formulations as water swelling or water soluble matrices. Polar lipids, for example monoglycerides, and surfactants can be used to solubilise hydrophobic or amphiphilic drugs and to formulate potential drug delivery vehicles such as emulsions, liposomes and cubic phases. In this thesis mixtures of these excipients are characterised in various environments, from dilute aqueous solutions to solid dispersions. Special focus has been on the understanding of the associating processes involved.</p><p>Detailed understanding of the association of cellulose ethers, of varying hydrophobicity, and amphiphilic substances is presented. The hydrophobicity of the polymer was found to have an impact on the interaction scheme. The amphiphiles were found to bind at lower amphiphile concentrations to a more hydrophobic polymer thus influencing both micro- and macroscopic structure of the aggregates. </p><p>The choice of counterion to the amphiphile has a small but significant effect on the interaction and the structure of the aggregates. Also amphiphilic drug molecules can interact with nonionic polymers in a similar way as surfactants in aqueous solution. Due to the higher cmc of the drug ibuprofen the interaction is largely influenced by the ionic strength of the solution. The type of amphiphile also influences the cooperativity of the amphiphile-polymer binding.</p><p>In more concentrated systems liquid crystals are formed into which the polymer interact with the amphiphiles. Both cubic and sponge phases were found with relatively large polymers interacting with polar lipids. These phases were found to swell and shrink mainly controlled by the amount of polymer inside them. Also membrane interacting substances added to the sponge phase could influence the size of the water channels in the phase. </p><p>In water free systems polymers and polar lipids were found to interact as well as forming solid dispersions. The behaviour of the phase separation between polymer and lipid depended on the concentration of the dispersed phase. The polar lipid was found to be distributed in the lamellar part of the semicrystalline polymer influencing the polymer folding.</p>

Actualment estem entrant a una nova era de la informació amb gran demanda de sistemes de comunicació sense fils. Nous serveis com dades i video requereixen transmissions fiables d'alta velocitat, fins i tot en escenaris d'alta mobilitat. A més a més, la dificultat d'assignar el limitat espectre radioelèctric juntament amb la necessitat d'incrementar el temps de vida de les bateries dels terminals mòbils, requereix el diseny de transceptors que usin la potència i l'ampla de banda disponibles de manera eficient. Les comunicacions multiportadora basades en OFDM són capaces de satisfer la majoria d'aquests requeriments. Però, entre altres reptes, reduir la sensibilitat a la amplificació no-lineal és un factor clau durant el diseny. En aquesta tesi doctoral s'analitza la sensibilitat dels sistemes multiportadora basats en OFDM a l'amplificació no-lineal i es consideren formes eficients per superar aquest problema. La tesi s'enfoca principalment al problema de reduir les fluctuacions de l'envolupant del senyal transmès. En aquest sentit es presenta també un estudi de les mètriques de l'envolupant del senyal, PAPR i CM. A més a més, basant-nos en l'anàlisis presentat es proposen noves tècniques per sistemes OFDM i MC-SS. Per MC-SS, també es tracta el diseny d'una tècnica de postprocessament en forma de detector multiusuari per canals no-lineals. / Actualmente estamos entrando en una nueva era de la información donde se da una gran demanda de sistemas de comunicación inalámbricos. Nuevos servicios como datos y vídeo requieren transmisiones fiables de alta velocidad, incluso en escenarios de alta movilidad. Además, la dificultad de asignar el limitado espectro radioeléctrico junto con la necesidad de incrementar el tiempo de vida de las baterías de los terminales móviles, requiere el diseño de transceptores que usen eficientemente la potencia y el ancho de banda disponibles. Las comunicaciones multiportadora basadas en OFDM son capaces de satisfacer la mayoría de dichos requerimientos. Sin embargo, entre otros retos, reducir su sensibilidad a la amplificación no-lineal es un factor clave durante el diseño. En esta tesis se analiza la sensibilidad de los sistemas multiportadora basados en OFDM a la amplificación no-lineal y se consideran formas eficientes para superar dicho problema. La tesis se enfoca principalmente al problema de reducir las fluctuaciones de la envolvente. En este sentido también se presenta un estudio de las métricas de la señal, PAPR y CM. Además, basándonos en el análisis presentado se proponen nuevas técnicas para OFDM y MC-SS. Para MC-SS, también se trata el diseño de un detector multiusuario para canales no-lineales. / We are now facing a new information age with high demand of wireless communication systems. New services such as data and video require achieving reliable high-speed transmissions even in high mobility scenarios. Moreover, the difficulty to allocate so many wireless communication systems in the limited frequency band in addition to the demand for long battery life requires designing spectrum and power efficient transceivers. Multicarrier communications based on OFDM are known to fulfill most of the requirements of such systems. However, among other challenges, reducing the sensitivity to nonlinear amplification has become a design key. In this thesis the sensitivity of OFDM-based multicarrier systems to nonlinear amplification is analyzed and efficient ways to overcome this problem are considered. The focus is mainly on the problem of reducing the envelope fluctuations. Therefore, a study of the signal metrics, namely PAPR and CM, is also presented. From the presented analysis, several new techniques for OFDM and MC-SS are proposed. For MC-SS, the design of a post-processing technique in the form of a multiuser detector for nonlinearly distorted MC-SS symbols is also addressed.

The aim of the presented work was to deposit cubic boron nitride thin films by magnetron sputtering under simultaneous stress relaxation by ion implantation. An in situ instrument based on laser deflectometry on cantilever structures and in situ ellipsometry, was used for in situ stress measurements. The characteristic evolution of the instantaneous stress during the layered growth of cBN films observed in IBAD experiments, could be reproduced for magnetron sputter deposition. To achieve simultaneous stress relaxation by ion implantation, a complex bipolar pulsed substrate bias source was constructed. This power supply enables the growth of cBN thin films under low energy ion irradiation (up to 200 eV) and, for the first time, the simultaneous implantation of ions with an energy of up to 8 keV during high voltage pulses. It was demonstrated that the instantaneous stress in cBN thin films can be released down to -1.1 GPa by simultaneous ion bombardment during the high voltage pulses. A simultaneous stress relaxation during growth is possible in the total investigated ion energy range between 2.5 and 8 keV. These are the lowest ion energies reported for the stress relaxation in cBN. Since such a substrate bias power supply is easy to integrate in existing process lines, this result is important for industrial deposition of thin films, not only for cubic boron nitride films. It was found that the amount of stress relaxation depends on the number of atomic displacements (displacements per atom: dpa) that are induced by the high energy ion bombardment and is therefore dependent on the ion energy and the high energy ion flux. In practise, this means that the stress relaxation is controlled by the product of the pulse voltage and the pulse duty cycle or frequency. The cantilever bending measurements were complemented on microscopic scale by x-ray diffraction (XRD). The analysis of the cBN (111) lattice distances revealed a pronounced biaxial compressive state of stress in a non-relaxed cBN film with d(111) being larger in out-of-plane than in in-plane direction. Post deposition annealing at 900 ° C of a sample with an ion induced damage of 1.2 dpa, resulted in a complete relaxation of the lattice with equal in-plane and out-of-plane lattice parameters. In the case of medium-energy ion bombardment, the in-plane and out-of-plane lattice parameters approach the value of the annealed sample with increasing ion damage. This is a clear evidence for stress relaxation within the cBN lattice. The stability of cBN under ion bombardment was investigated by IR spectroscopy and XRD. The crystalline cBN was found to be very stable against ion irradiation. However a short-range ordered, sp3/sp2 - mixed phase may exist in the films, which could be preferably converted to a sp2 -phase at high damage values. From the analysis of the near surface region by XANES, it can be concluded the stress relaxation by the energetic ion bombardment is less at the surface than in the bulk film. This is explained with the dynamic profile of the ion induced damage, that reaches the stationary bulk value in 15-20 nm depth, whereas it is decreasing towards the surface. This fits with the results that the stress relaxation is dependent on the amount of ion induced damage. Comparing the results from substrate curvature measurement, XRD, XANES, and IR spectroscopy possible mechanisms of stress relaxation are discussed. Concluding the results, it can be stated that using simultaneous ion implantation for stress relaxation during the deposition it is possible to produce BN films with a high amount of the cubic phase and with very low residual stress.