Es heißt, moderne Marktwirtschaften seien sich selbst regulierende Systeme. Dies gelte auch für die Moral der Akteure. Die Finanzkrisen der letzten Jahre haben die Frage nach der Stärke der Selbstheilungskräfte aufgeworfen. Dies wird im Aufsatz untersucht. Dazu werden zunächst die geisteswissenschaftlichen Konzeptionen des Liberalismus, des Ordoliberalismus und der Zentralverwaltungswirtschaft vorgestellt. Dann wird eine evolutionswissenschaftliche Konzeption dagegengestellt. Es zeigt sich, dass die geisteswissenschaftlichen Konzeptionen das „eigentliche“ Zielsystem der Akteure nur unvollkommen berücksichtigen. Sie über- oder unterschätzen daher das Vermögen der Systeme zur Selbstheilung. Die größte Übereinstimmung finden wir beim Ordoliberalismus, der mit seiner Skepsis in die Selbstheilungskräfte freier Märkte Recht hat: Es muss einen institutionellen Ordnungsrahmen geben, der mit der wünschenswerten gesellschaftlichen Moral besser als bisher zu verknüpfen ist. Für die weitere Forschung sehen wir die wichtige Aufgabe, die Selbstheilungskräfte der Gesellschaft in Bezug auf moralisches Verhalten genauer zu erforschen. / It has been said, modern market economies are self-regulating systems. This would also be true for the moral standards of its actors. The financial crises of recent years have put the strength of self-healing capacities in question. This will be investigated in the following paper. In order to do so, concepts of social sciences such as liberalism, ordoliberalism and central command economy will be presented. Subsequently, evolution theory will oppose these concepts. The analysis shows that social sciences only imperfectly recognize the essential objectives of actors. They over- or underestimate the self-healing capabilities of the economy systems. The largest conformity was found in the ordoliberalism, whose skeptics in self-healing capacities of free markets have been upheld. An institutional framework has to be put in place, which is more strongly linked to the morals of civil society as has been the case so far. In the future, one important task for research will be to further investigate self-healing capacities of societies in light of moral behavior.

Les matériaux composites à matrice céramique CMC, sont généralement formés d’au moins deux matériaux ayant une forte capacité d’adhésion. Ces matériaux sont principalement composés de renforts fibreux assurant la tenue mécanique de la structure et d’une matrice qui permet sa cohésion. Utilisées principalement dans le domaine de l’aéronautique, elles sont reconnues pour leur bonne tenue mécanique, leur réfractarité élevée tout en conservant une densité faible. Par contre, l’inconvénient majeur associé à ces matériaux est l’apparition de fissures qui sont dues soit au procédé de fabrication soit aux sollicitations mécaniques externes.Dans ce travail, une attention toute particulière est consacrée aux composites à matrice auto-cicatrisante dont la principale propriété est l'aptitude à "réparer" les effets de la fissure par formation d'un verre visqueux.Ces verres visqueux se forment au sein de la fissure grâce à l’oxydation des éléments qui constituent la matrice. Selon la température, différents verres peuvent être formés.Leur fonction est de reboucher les fissures de taille micrométrique de façon à ralentir la diffusion de l'oxygène en direction des fibres et éviter leur rupture par oxydation.Cependant, pour des systèmes en rotation rapide tels que les turbines basse pression des moteurs d’avion (pièce étudiée actuellement), on peut s'interroger quant à la mobilisation du verre visqueux cicatrisant dans un système complexe géométriquement et inhomogène du point de vue de la nature des surfaces. Pour approcher le comportement du verre cicatrisant dans un système modèle mais néanmoins réaliste, une approche de modélisation numérique a été entreprise. L'outil numérique utilisé pour cette étude est le code de calcul Thétis développé à l’I2M. Celui-ci est adapté à ce type de simulation puisqu'il permet la modélisation d'écoulements diphasiques incluant des phénomènes physiques complexes tels que le mouillage. Ainsi, l'objectif de ce travail est-il de déterminer les limites d'utilisation de ce type de matériau en fonction des conditions auxquels il est soumis en évaluant la mobilité du verre cicatrisant dans la fissure. / The Ceramic Matrix Composites (CMCs) are generally formed of at least two materials having strong adhesion ability. These materials are mainly composed of fibrous reinforcement which ensures the mechanical resistance of the structure and a matrix which allows its cohesion.Used mainly in aerospace, the CMCs are highly valued for their good mechanical strength, their good refractory properties associated with a low density.However, the major drawback of these materials is cracks formation due to manufacturing process or to external mechanical stresses.In this study, we focus on composite materials having self-healing properties. These materials have the ability to produce healing viscous glasses in presence of oxygen.These viscous glasses are formed in the crack under the influence of oxidation of matrix compounds. Depending on the temperature level, glasses of different natures are formed.Their main role is to reseal the micrometric cracks, to limit oxygen access to the fibers in order to prevent their rupture by oxidation.However, for fast rotating systems such as the low pressure turbine of aircraft engines, we may question about mobilization of such a viscous glass in a system characterized by a complex geometry and chemically inhomogeneous surfaces.Therefore, a numerical approach was undertaken, using "Thetis" software. Developed at I2M, this software allows us modelling two-phase flow in model simplified geometry (reflecting however reality) including complex phenomena such as wetting. Numerical results yield to the determination of operating limitations of CMCs in terms of healing efficiency as a function of external mechanical stresses (rotation) and crack geometry.

Web services have become a prominent paradigm for building of both inter and intra-enterprise business processes. These processes are composed from existing Web services based on defined requirements. Standards and techniques have been developed to aid in the dynamic composition of services. However, these approaches are limited when it comes to the handling of unexpected events. This dissertation presents the results of experiments that investigated numerous problems related to Web service composition processes. Based on the investigation, a fault taxonomy was formulated. Faults were grouped into three broad categories, each representing a distinct problem stage. The investigation into faults gave rise to the issue of fault recovery and continued process execution. A list of requirements for self-healing Web service composition was identified, while a new self-healing cycle was exploited based on the MAPE cycle (Monitor, Analyzer, Planner, Executive). The proposed self-healing composition cycle consists of three modules: Plan Generation Module, Plan Execution Module and Failure Analysis Module. The plan execution module, consisting of the execution and run-time monitoring phases, and the failure analysis module, consisting of the analysis and sensemaking phases, were found to be vital to self-healing Web service composition. Self healing Web service composition and the goal of self-healing were achieved through the use of Hierarchical Task Network (HTN) planning systems. / Dissertation (MSc)--University of Pretoria, 2009. / Computer Science / unrestricted

Los materiales autosanables son materiales con la capacidad de reparar sus daños de forma autónoma o con ayuda mínima de estímulos externos. En el campo de la construcción, el desarrollo de elementos autosanables aumentará la durabilidad de las estructuras y reducirá las acciones de mantenimiento y reparación. Los elementos de hormigón armado presentan frecuentemente pequeñas fisuras (< 0.3 mm), no relevantes mecánicamente, pero que pueden suponer un punto de entrada para agentes agresivos. El hormigón tiene una cierta capacidad de autosanación, capaz de cerrar pequeñas fisuras, producida principalmente por la hidratación continuada y la carbonatación. Estudios recientes han intentado mejorar dicha capacidad y diseñar productos específicos para conseguirla. Estos productos incluyen, entre otros, aditivos cristalinos, agentes micro o macroencapsulados, e incluso el uso de bacterias. Los aditivos cristalinos (CA) son un tipo de aditivo para hormigón que se considera que aporta propiedades de autosanación. No obstante, la falta de conocimiento sobre su comportamiento limita su uso. Además, los métodos para evaluar la autosanación en hormigones no están estandarizados todavía. Esto complica la realización de un análisis crítico de los diferentes productos y métodos de evaluación propuestos en la literatura. Para responder a esta falta de conocimiento, los objetivos de esta tesis son: 1) estudiar y proponer procedimientos experimentales para evaluar los fenómenos de autosanación en hormigón y, 2) evaluar experimentalmente las mejoras producidas al introducir aditivos cristalinos. Esta tesis incluye como ensayos para la determinación de la autosanación: la evaluación del cierre de fisuras, la permeabilidad al agua, flexión a tres puntos y absorción capilar. Además, se han realizado varias campañas experimentales para validar los ensayos propuestos. Posteriormente, estos ensayos se han utilizado para analizar la influencia de varios parámetros, incluyendo entre otros: presencia de aditivos cristalinos, nivel de daño, tiempo necesario para el sanado, composición del hormigón y condiciones de sanado. Finalmente, se analizan los efectos producidos al añadir aditivos cristalinos en hormigón en la fluidez, resistencia e hidratación. Los resultados muestran que el cierre de fisuras es un ensayo eficaz y sencillo para evaluar la autosanación. Sin embargo, la orientación de la fisura durante el sanado ha resultado ser de gran importancia, y no considerar este aspecto puede llevar a conclusiones engañosas. El ensayo de permeabilidad al agua propuesto en este trabajo presenta una buena estabilidad y es fácil de implementar en laboratorios. Además, las relaciones obtenidas entre los parámetros de fisura y la permeabilidad del agua han confirmado la relación cúbica indicada en la literatura. Este trabajo muestra que analizar la eficiencia de autosanado mediante el cierre de fisuras puede llevar a una sobreestimación de la capacidad de sanación, comparada con los resultados obtenidos mediante permeabilidad. Los ensayos de sorptividad resultaron fáciles de implementar, sin embargo, los resultados obtenidos mostraron una alta dispersión y sensibilidad a las variaciones en las fisuras producidas durante el proceso de prefisuración. En cuanto a la evaluación de la recuperación mecánica, los resultados muestran que la evolución de las propiedades del hormigón con el tiempo es un parámetro que debe considerarse, especialmente en fisuras de edades tempranas. En este trabajo se ha obtenido que los aditivos cristalinos potencian las reacciones de autosanación, pero tienen una capacidad limitada. La proximidad de los CA a la industria es un punto positivo para su inclusión como un nuevo tipo de aditivo de hormigón. Sin embargo, los resultados obtenidos en esta tesis indican que se necesitan más análisis para determinar sus efectos completos en hormigón, especialmente con respect / Self-healing materials are materials with the capability to repair their damage autonomously or with minimal help from an external stimulus. In the construction field, the development of self-healing elements will increase the durability of structures and reduce their maintenance and repair actions. Reinforced concrete elements frequently suffer small cracks (< 0.3 mm), not relevant mechanically, but they can be an entrance point for aggressive agents. Concrete has a natural self-healing capability able to seal small cracks, produced by the continuing hydration and carbonation processes. Recent studies have attempted to improve that healing capability and to design specific products to achieve it. These products include, among others: crystalline admixtures, micro- or macro-encapsulated agents, and even the use of bacteria. Crystalline admixtures (CA) are a concrete admixture that is claimed to provide self-healing properties. However, the lack of knowledge on their behavior and self-healing properties limits their usage. In addition, the methods to evaluate the self-healing capability of mortar and concrete are not standardized yet. This complicates the performance of a critical analysis of the different self-healing products and evaluation methods found in the literature. In order to answer to this lack of knowledge, the objectives of this thesis are: 1) to study and propose experimental procedures in order to evaluate self-healing in concrete and, 2) to evaluate experimentally the self-healing enhancements produced when introducing crystalline admixtures. This thesis includes the following tests for the determination of the self-healing: the evaluation of crack closing, water permeability, three point bending tests and capillary absorption test. In addition, several experimental campaigns have been performed with the objective of validating the proposed tests. Afterwards, these methods have been used to analyze the influence of several parameters, including among others: the presence of crystalline admixtures, the damage extent, healing time needed, concrete composition and healing conditions. Finally, the effects that crystalline admixtures produce in concrete are analyzed in terms of slump, strength and hydration. The results show that crack closing is an effective and simple method to evaluate self-healing. However, the orientation of the crack during healing is of great importance, and disregarding this aspect may lead to misleading conclusions. The water permeability method proposed in this work has good stability and it is easy to implement in concrete laboratories. Moreover, the relations obtained between crack parameters and water permeability confirmed the cubic relation, as reported in the literature. This work shows that analyzing healing efficiency by means of crack closing tends to overestimate self-healing if compared with the results obtained by means of water permeability. Sorptivity analysis tests were easy to implement, however, the results obtained in this work showed high dispersion and sensitivity to the variations of the cracks introduced during the precracking process. Regarding the evaluation of mechanical recoveries, the results show that the evolution of concrete properties with time is a parameter of importance that, therefore, should be considered, especially for early age cracks. In this work, crystalline admixtures have been reported as an enhancer of self-healing reactions, but with a limited capacity of enhancement. The proximity of CA to the industry is a positive point to their inclusion as a new type of admixture for concrete. However, the results obtained in this thesis indicate further analyses are needed to determine their full effects on concrete, especially regarding self-healing. / Els materials autosanables són materials amb la capacitat de reparar els seus danys de forma autònoma o amb ajuda mínima d'estímuls externs. En el camp de la construcció, el desenvolupament d'elements autosanables augmentarà la durabilitat de les estructures i reduirà les accions de manteniment i reparació. Els elements de formigó armat presenten freqüentment fissures menudes (< 0.3 mm), no rellevants des del punt de vista mecànic, però poden suposar un punt d'entrada per a agents agressius. El formigó té una capacitat de autosanació capaç de tancar fissures menudes, produïda principalment per la hidratació continuada i la carbonatació. Estudis recents han intentat millorar eixa capacitat i dissenyar productes específics per aconseguir-la. Aquests productes inclouen, entre d'altres, additius cristal·lins, agents micro- o macroencapsulats, i fins i tot l'ús de bacteris. Els additius cristal·lins (CA) són un tipus d'additiu reductor per formigó que es considera que proporciona propietats de autosanació. No obstant, la manca de coneixement sobre el seu comportament limita el seu ús. A més, els mètodes per avaluar la autosanació de formigons encara no estan estandarditzats. Açò complica la realització d'una anàlisi crítica dels diferents productes i mètodes d'avaluació proposats a la literatura. Per respondre a aquesta manca de coneixement, els objectius d'aquesta tesi són: 1) estudiar i proposar procediments experimentals per avaluar els fenòmens d'autosanació en formigó i, 2) avaluar experimentalment les millores produïdes en introduir additius cristal·lins. Aquesta tesi inclou com assajos per a la determinació de l'autosanació: l'avaluació del tancament de fissures, la permeabilitat a l'aigua, flexió a tres punts i absorció capil·lar. A més, s'han realitzat diverses campanyes experimentals per validar els assajos proposats. Posteriorment, aquests assajos s'han utilitzat per analitzar la influència de diversos paràmetres: presència d'additius cristal·lins, nivell de dany, temps necessari per a la sanació, composició del formigó i condicions de sanació. Finalment, s'analitzen els efectes produïts en afegir additius cristal·lins en formigó en fluïdesa, resistència i hidratació. Els resultats mostren que el tancament de fissures és un assaig eficaç i senzill per avaluar l'autosanació. No obstant això, l'orientació de la fissura durant la sanació ha resultat ser de gran importància, i no considerar aquest aspecte pot portar a conclusions enganyoses. L'assaig de permeabilitat a l'aigua proposat presenta una bona estabilitat i és fàcil d'implementar en laboratoris. A més, les relacions obtingudes entre els paràmetres de fissura i la permeabilitat a l'aigua han confirmat la relació cúbica de la literatura. Aquest treball mostra que analitzar l'eficiència de l'autosanació amb el tancament de fissures pot sobreestimar la capacitat de sanació, comparada amb els resultats obtinguts-dues mitjançant permeabilitat a l'aigua. Els assajos de sorptivitat van resultar fàcils d'implementar, però, els resultats obtinguts en aquest treball van mostrar una alta dispersió i sensibilitat a les variacions en les fissures produïdes durant el procés de prefissuració. Pel que fa a l'avaluació de la recuperació mecànica, els resultats mostren que l'evolució de les propietats del formigó amb el temps és un paràmetre d'importància que, per tant, s'ha de considerar, especialment per fissures primerenques. En aquest treball s'ha obtingut que els additius cristal·lins potencien les reaccions d'autosanació, però tenen una capacitat limitada. La proximitat dels CA a la indústria és un punt positiu per a la seva inclusió com un nou tipus d'additiu de formigó. Tanmateix, els resultats obtinguts en aquesta tesi indiquen que calen més anàlisis per determinar els seus efectes complets en formigó, especialment pel que fa a l'autosanació. / Roig Flores, M. (2018). Self-healing concrete: efficiency evaluation and enhancement with crystalline admixtures [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/100082 / TESIS

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Dans le cadre des recherches menées sur l'amélioration de la résistance à l'oxydation des gaines de combustible en conditions accidentelles, des revêtements Cr-Al-C et Cr2AlC ont été développés dans ce travail. Dans la première partie, nous avons étudié le procédé HiPIMS afin de comprendre l'effet de différents paramètres de dépôt sur le plasma et les propriétés des films obtenus. Il en ressort que malgré un bombardement ionique plus intense, un apport supplémentaire d'énergie est requis pour obtenir un revêtement cristallin. Des recuits à partir de 500°C sous argon de systèmes Cr-Al-C tels que déposés permettent ainsi une cristallisation partielle des revêtements en Cr2AlC à une température suffisamment basse pour être compatible avec la métallurgie des alliages de zirconium. Dans un second temps, l'évaluation du comportement à haute température de ces deux types de revêtements, recuits ou non, a révélé un effet protecteur contre l'oxydation rapide du zirconium jusqu'à 1200°C en atmosphère oxydante grâce à la formation d'une couche d'oxyde continue. Cette couche est constituée d'un mélange d'alumine α et de chromine pour le revêtement de Cr-Al-C tandis que seule l'alumine α est présente pour le revêtement Cr2AlC dans les premiers instants de l'oxydation. Ensuite, en raison de l'appauvrissement en Al, les revêtements se dégradent en formant une couche intermédiaire résiduelle de carbure Cr7C3 servant de réservoir de Cr jusqu'à complète oxydation. Ces résultats ont également montré la perte d'une partie du réservoir d'Al par diffusion dans les alliages Zr. Une architecture multicouche a été développée pour limiter cette diffusion et ainsi prolonger la durée de vie du revêtement. L'ajout d'un intercalaire en Mo pour bloquer la diffusion d'Al dans le substrat s'est avéré peu concluant, le molybdène s'évaporant à haute température. Les systèmes base Cr-Al-C revêtus chrome, présentent quant à eux, un comportement amélioré par rapport aux revêtements monocouches. / This study aims to improve oxidation resistance of nuclear fuel claddings in accident conditions. In this context, Cr-Al-C and Cr2AlC coatings deposition and their behavior were studied. Firstly, we investigated the influence of HiPIMS process parameters on the properties of the plasma and the deposited films. Despite more intense ionic fluxes due to the HiPIMS process, coatings do not crystallize without an additional energy supply. Partially crystallized Cr2AlC thin films were obtained by a 500°C annealing of as-deposited Cr-Al-C coatings. This two-step process is a viable solution to protect nuclear claddings with Cr2AlC coating while maintaining the metallurgical properties of the zirconium-based substrates. Secondly, the assessment of the oxidation resistance of as-deposited and annealed coatings revealed significant protective effect against rapid oxidation under dry and wet air at high temperatures (up to 1200°C) owing to the formation of a continuous oxide layer. During the first stages of oxidation, this layer is made of α Al2O3 and Cr2O3 for as-deposited coating while only α-Al2O3 is present for the annealed one. Because of Al depletion, coatings later deteriorate and form a residual and porous intermediate chromium carbide (Cr7C3) layer which further fully oxidizes. It was shown that the inward diffusion of Al with Zr also accelerates the coating deterioration. To improve the oxidation resistance of these coatings, multilayered architectures were developed. Adding a molybdenum interlayer as diffusion barrier globally decreased the oxidation resistance of the coating. In contrast, topping Cr-Al-C and Cr2AlC with a Cr layer improved oxidation behavior over single-layer coatings.

Orientador: Peter Hammer / Resumo: Este trabalho relata uma investigação detalhada das propriedades estruturais e eletroquímicas de revestimentos de polimetilmetacrilato (PMMA)-sílica. Espectroscopia Raman e análise térmica mostraram que o ajuste da quantidade de peróxido de benzoíla (BPO), como um parâmetro crítico de síntese, melhora a eficiência de polimerização do metilmetacrilato (MMA), levando a uma estrutura híbrida altamente reticulada. A espectroscopia de impedância eletroquímica (EIS) mostrou para revestimentos depositados sobre aço carbono (A1020) e liga de Al (AA7075) uma resposta de impedância capacitiva quase ideal, mantendo o módulo de impedância de baixa frequência de até 10 GΩ cm2 essencialmente inalterado durante 19 meses de imersão em NaCl 3,5%. Embora revestimentos passivos de alto desempenho tenham sido desenvolvidos, pites de corrosão podem afetar significativamente sua durabilidade. Assim, a inibição da corrosão ativa induzida por íons lítio e cério em revestimentos de sílica sol-gel de PMMA foi investigada. A adição de carbonato de lítio produziu revestimentos com melhor conectividade dos nós de sílica nanométricos e forte adesão ao substrato de alumínio. Os resultados de EIS mostraram que as concentrações de lítio mais altas resultam em um aumento no módulo de impedância e induzem a autorregeneração que aumenta significativamente sua vida útil dos revestimentos. Time-of-flight secondary ion mass spectrometry (ToFSIMS) e a espectroscopia de fotoelétrons excitados por raios-X (XPS) suger... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work reports on a detailed investigation of the structural and electrochemical properties of poly(methyl methacrylate) (PMMA)-silica coatings. Raman spectroscopy and thermal analysis showed that the fine-tuning of the benzoyl peroxide (BPO) amount, as a critical synthesis parameter, improves the polymerization efficiency of methyl methacrylate (MMA), leading to a highly cross-linked hybrid structure. Electrochemical impedance spectroscopy (EIS) showed for coatings deposited on carbon steel (A1020) and Al alloy (AA7075) a quasi-ideal capacitive impedance response, maintaining the low frequency impedance modulus of up to 10 GΩ cm2 essentially unchanged during 19 months of immersion in 3.5% NaCl. Although high performance passive coatings have been developed, pitting can significantly affect their durability. Hence, active corrosion inhibition induced by lithium and cerium ions in PMMA-silica sol-gel coatings was investigated. The addition of lithium carbonate yielded coatings with improved connectivity of nanometric silica cross-link nodes and stronger adhesion to the aluminum substrate. EIS results showed that higher lithium concentrations result in an increased impedance modulus and induce the self-healing ability, extending significantly the service life of the coatings. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) suggest that the regeneration process occurs by means of lithium ions leaching from the adjacent coat... (Complete abstract click electronic access below) / Doutor

Orientador: Assis Vicente Benedetti / Resumo: Os revestimentos de poliuretano (PU) foram preparados a partir de óleos vegetais (crambe e mamona) e modificados pela incorporação de inibidores de corrosão (tanino condensado). A reação foi monitorada caracterizando os produtos intermediários (poliéster e pré-polímero). O poliéster foi caracterizado pela solubilidade em metanol, índice de acidez, grupos hidroxila e espectroscopia no infravermelho por transformada de Fourier com refletância total atenuada (FTIR), e o pré-polímero foi caracterizado por teor de sólido, teor de solvente, isocianato livre (NCO) e FTIR. Os revestimentos de PU foram caracterizados por FTIR e absorção de água. Esses revestimentos foram aplicados sobre as ligas de alumínio com extensômetro. O processo de cura foi conduzido em temperatura ambiente (~25 oC). A espessura dos revestimentos foi determinada por microscopia eletrônica de varredura (SEM) e a adesão foi avaliada pela Norma ASTM D3359. Após a caracterização química e morfológica dos revestimentos foi realizado o estudo eletroquímico. A resistência à corrosão e o processo de degradação do filme (longevidade da ação do revestimento), foram estudadas por medidas de potencial em circuito aberto (EOCP) e espectroscopia de impedância eletroquímica (EIS) em solução aquosa 0,6 mol L-1 NaCl com o tempo de imersão. Foram empregadas técnicas eletroquímicas localizadas como espectroscopia de impedância eletroquímica local (LEIS) em solução aquosa 0,005 mol L-1 NaCl e as técnicas de varredura com eletrodo ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Polyurethane (PU) coatings were prepared from vegetable oils (crambe and castor) and modified by the incorporation of corrosion inhibitors (condensed tannins). The reaction was monitored by characterizing the intermediate products (polyester and prepolymer). Polyester was characterized by solubility in methanol, acidity index, hydroxyl groups and attenuated total reflectance Fourier transform infrared spectroscopy (FTIR), and the prepolymer was characterized by solid content, solvent content, free-isocyanate (NCO) groups and FTIR. PU coatings were characterized by FTIR and water uptake. These coatings were applied on aluminum alloys with an extensometer. The curing process was carried out at room temperature (~25 oC). The thickness of the coatings was determined by scanning electron microscopy (SEM) and the adhesion was assessed using the ASTM D3359 standard. After the chemical and morphological characterization of the coatings, the electrochemical study was carried out. The corrosion resistance and the film degradation process (longevity of the coating action) were studied by open circuit potential measurements (EOCP) and electrochemical impedance spectroscopy (EIS) in 0.6 mol L-1 NaCl aqueous solution with the immersion time. Localized electrochemical techniques were also used, such as local electrochemical impedance spectroscopy (LEIS) in 0.005 mol L-1 NaCl aqueous solution and scanning techniques with vibrating electrode (SVET) and with ion-selective electrode (SIET), in ... (Complete abstract click electronic access below) / Doutor

As software systems have grown in size and complexity, the costs of maintaining such systems increases steadily. In the early 2000's, IBM launched the autonomic computing initiative to mitigate this problem by injecting feedback control mechanisms into software systems to enable them to observe their health and self-heal without human intervention and thereby cope with certain changes in their requirements and environments. Self-healing is one of several fundamental challenges addressed and includes software systems that are able to recover from failure conditions. There has been considerable research on software architectures with feedback loops that allow a multi-component system to adjust certain parameters automatically in response to changes in its environment. However, modifying the components' source code in response to failures remains an open and formidable challenge. Automatic program repair techniques aim to create and apply source code patches autonomously. These techniques have evolved over the years to take advantage of advancements in programming languages, such as reflection. However, these techniques require mechanisms to evaluate if a candidate patch solves the failure condition. Some rely on test cases that capture the context under which the program failed---the patch applied can then be considered as a successful patch if the test result changes from failing to passing. Although test cases are an effective mechanism to govern the applicability of potential patches, the automatic generation of test cases for a given scenario has not received much attention. ReCrash represents the only known implementation to generate test cases automatically with promising results through the use of low-level instrumentation libraries. The work reported in this thesis aims to explore this area further and under a different light. It proposes the use of Aspect-Oriented Programming (AOP)---and in particular of AspectJ---as a higher-level paradigm to express the code elements on which monitoring actions can be interleaved with the source code, to create a representation of the context at the most relevant moments of the execution, so that if the code fails, the contextual representation is retained and used at a later time to automatically write a test case. By doing this, the author intends to contribute to fill the gap that prevents the use of automatic program repair techniques in a self-healing architecture. The prototype implementation engineered as part of this research was evaluated along three dimensions: memory usage, execution time and binary size. The evaluation results suggest that (1) AspectJ introduces significant overhead with respect to execution time, (2) the implementation algorithm causes a tremendous strain on garbage collection, and (3) AspectJ incorporates tens of additional lines of code, which account for a mean size increase to every binary file of a factor of ten compared to the original size. The comparative analysis with ReCrash shows that the algorithm and data structures developed in this thesis produce more thorough test cases than ReCrash. Most notably, the solution presented here mitigates ReCrash's current inability to reproduce environment-specific failure conditions derived from on-demand instantiation. This work can potentially be extended to apply in less-intrusive frameworks that operate at the same level as AOP to address the shortcomings identified in this analysis. / Graduate

Static Random Access Memory (SRAM) cells in ultra-low power Integrated Circuits (ICs) based on nanoscale Complementary Metal Oxide Semiconductor (CMOS) devices are likely to be the most vulnerable to large-scale soft errors. Conventional error correction circuits may not be able to handle the distributed nature of such errors and are susceptible to soft errors themselves. In this thesis, a distributed error correction circuit called Self-Healing Cellular Automata (SHCA) that can repair itself is presented. A possible way to deploy a SHCA in a system of SRAM-based embedded program memories (ePM) for one type of chip multi-processors is also discussed. The SHCA is compared with conventional error correction approaches and its strengths and limitations are analyzed.