Le combustible nucléaire des Réacteurs à Eau sous Pression (REP), sous forme de pastilles d’oxyde d’uranium UO2 (ou MOx), est confiné dans un gainage en alliage de zirconium. Ce gainage est très important car il représente la première barrière de confinement contre la dissémination des produits de fission, générés par la réaction nucléaire, vers le milieu extérieur. La corrosion par le milieu primaire des alliages de zirconium, en particulier l’alliage Zircaloy-4, est un des facteurs limitant le temps de séjour en réacteur des crayons combustibles (pastilles UO2 + gainage). Afin de permettre aux exploitants de centrales d’optimiser la gestion des cœurs et de prolonger la durée de vie des crayons combustibles en réacteur, de nouveaux alliages à base de zirconium-niobium (M5®) ont été développés. Or, les mécanismes de corrosion de ces derniers ne sont, en l’état, pas complètement élucidés du fait notamment de la complexité de ces matériaux, de l’environnement de corrosion et de la présence de l'irradiation venant du combustible nucléaire. De ce fait, cette thèse porte spécifiquement sur l’effet de la radiolyse et des défauts induits par l’irradiation aux ions dans la matrice métallique et dans la couche d’oxyde sur la vitesse de corrosion de l’alliage Zircaloy-4 et M5®. L’objectif est de déconvoluer la part de l’influence des dommages d’irradiation subis par la matrice métallique, de celle relative aux défauts créés dans l’oxyde et de celle liée à la radiolyse du milieu primaire sur la vitesse d’oxydation des alliages de zirconium en réacteur.1) Concernant l’effet de l’irradiation de la matrice métallique sur la vitesse d’oxydation : des boucles de dislocation de type <a> apparaissent et entrainent une augmentation de la vitesse d’oxydation des deux alliages. Pour le M5®, en plus de ce premier effet, une précipitation d’aiguilles fines de niobium diminue la concentration en niobium en solution solide dans la matrice métallique et in fine dans l’oxyde, ce qui réduit fortement la vitesse d’oxydation de l’alliage.2) Concernant l’effet de l’irradiation de la couche d’oxyde sur la vitesse d’oxydation : les défauts générés par les cascades de déplacement dans l’oxyde augmentent la vitesse d’oxydation des matériaux. Pour le M5®, la germination de zones enrichies en niobium par irradiation de l’oxyde entraine une également diminution de la concentration en niobium en solution solide dans l’oxyde, ce qui réduit une nouvelle fois, la vitesse d’oxydation de cet alliage.3) Concernant l’effet de la radiolyse de l’eau : nous n’avons pas relevé d’effet considérable de la radiolyse sur la corrosion de l’alliage Zy4 ou M5® dans nos conditions expérimentales. / The nuclear fuel of pressurized water reactors (PWR) in the form of uranium oxide UO2 pellets (or MOX) is confined in a zirconium alloy cladding. This cladding is very important because it represents the first containment barrier against the release of fission products generated by the nuclear reaction to the external environment. Corrosion by the primary medium of zirconium alloys, particularly the Zircaloy-4, is one of the factors limiting the reactor residence time of the fuel rods (UO2 pellets + cladding). To optimize core management and to extend the lifetime of the fuel rods in reactor, new alloys based on zirconium-niobium (M5®) have been developed. However, the corrosion mechanisms of these are not completely understood because of the complexity of these materials, corrosion environment and the presence of radiation from the nuclear fuel. Therefore, this thesis specifically addresses the effects of radiolysis and defects induced by irradiation with ions in the matrix metal and the oxide layer on the corrosion rate of Zircaloy-4 and M5®. The goal is to separate the influence of radiation damage to the metal, that relating to defects created in the oxide and that linked to radiolysis of the primary medium on the oxidation rate of zirconium alloys in reactor.1) Regarding effect of irradiation of the metal on the oxidation rate: <a> type dislocation loops appear and increase the oxidation rate of the two alloys. For M5®, in addition to the first effect, a precipitation of fines needles of niobium reduced the solid solution of niobium concentration in the metal and ultimately in the oxide, which strongly reduces the oxidation rate of the alloy.2) Regarding the effect of irradiation of the oxide layer on the oxidation rate: defects generated by the nuclear cascades in the oxide increase the oxidation rate of the two materials. For M5®, germination of niobium enriched zones in irradiated oxide also causes a decrease of the niobium concentration in solid solution in the oxide, which once again, reduced the oxidation rate of this alloy.3) Regarding the effect of water radiolysis: We did not identify any significant effect of radiolysis on corrosion of the alloys under our experimental conditions.

Cette recherche vise à établir les propriétés fondamentales d'un système formel aux preuves circulaires introduit par Santocanale, auquel on a rajouté la règle de coupure. On démontre, dans un premier temps, qu'il y a une pleine correspondance entre les preuves circulaires et les flèches issues des catégories dites µ-bicomplètes. Ces flèches sont celles que l'on peut définir purement à partir des outils suivants: les produits et coproduits finis, les algèbres initiales et les coalgèbres finales. Dans la catégorie des ensembles, les preuves circulaires dénotent donc les fonctions qu'on peut définir en utilisant les produits cartésiens finis, les unions disjointes finies, l'induction et la coinduction. On décrit également une procédure d'élimination des coupures qui produit, à partir d'une preuve circulaire finie, une preuve sans cycles et sans coupures, mais possiblement infinie. On démontre que l'élimination des coupures fournit une sémantique opérationnelle aux preuves circulaires, c'est-à-dire qu'elle permet de calculer les fonctions dénotées par celles-ci, par le moyen d'une sorte d'automate avec mémoire. Enfin, on s'intéresse au problème de la puissance expressive de cet éliminateur de coupures, c'est-à-dire à la question de caractériser la classe des expressions qu'il peut calculer. On démontre, par une simulation, que l'éliminateur des coupures est strictement plus expressif que les automates à pile d'ordre supérieur. / This research aims at establishing the fundamental properties of a formal system with circular proofs introduced by Santocanale, to which we added the cut rule. We first show that there is a full correspondence between circular proofs and arrows from the so-called µ-bicomplete categories. These arrows are those that can be defined purely from the following tools: finite products and coproducts, initial algebras and final coalgebras. In the category of sets, circular proofs denote functions that one can define by using finite cartesian products, finite disjoint unions, induction and coinduction. We also describe a cut-elimination procedure that produces, from a given finite circular proof, a proof without cycles and cuts, but which may be infinite. We prove that cut-elimination gives an operational semantics to circular proofs, which is to say that they allow to compute the functions denoted by them, by using a sort of automaton with memory. Finally, we are interested in finding the expressive power of that cut-eliminating automaton. In other words, we want to characterize the class of functions that it can compute. We show, through a simulation, that the cut-eliminating automaton is strictly more expressive than higher-order pushdown automata.

Yes / In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (ε <; 0) and negative permeability (μ <; 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called “metamaterials”. These artificial structures include series left-handed (LH) capacitances (C L ), shunt LH inductances (L L ), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterialTLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems. / This work was supported in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE) under Grant RTI2018-095499-B-C31, in part by the Innovation Programme under Grant H2020-MSCA-ITN-2016 SECRET-722424, and in part by the financial support from the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/E022936/1.

Printing since many years has been a well-known high throughput technology for producing replications of graphic arts entities (texts, images, aesthetics, gloss and physical impressions) over large varieties of substrates which are dedicated for various needful applications like newspapers, magazines, posters, official documents, packages, braille, textiles, decorative articles and many more. Due to the fact, that printing is a liquid-solution based replication process, where basic ink and substrate are needed, it is now not only limited to printing of graphic arts. Whenever an ink is deposited over a defined substrate and the process can be multiplied, it can be termed as printing and once the final product contains a functionality other than graphic arts application, it can be called as “Printed Functionality”. Some examples for printed functionalities can be found in the following fields: A. Printed electronics (using inks having electronic properties); B. Printed micro-fluidics (using inks having polymeric and elastic properties for directive purposes); C. 3-Dimensional printing (using inks containing binding properties for developing three dimensional structures); D. Printed photonics (using inks having self-assembling properties for building-up symmetric micro-structures); E. Printed pyroelectrics (using inks containing thermally flammable properties); F. Printed ceramics (using inks with ceramic particles) and G. Printed optics and functional surfaces (using inks with transparency, absorbency and reflective properties). All these mentioned applications require functional inks which in turn exhibits some physical-chemical properties e.g. particle size, particle loading, fluid’s rheological properties etc. These properties determine the feasibility of the material’s deposition (in this case the functional inks) with a suitable printing technology. The inkjet printing technology among others has several advantages such as contactless deposition processability, digitalization (batch size one & turn-over time zero), user defined customization and adaptation, industrial relevance, minimal ink demand for R&Ds, freedom of substrate regularity and µm-scale print accuracy etc. Some of the imminent players in the inkjet printing technology market are Canon, Kodak, Hewlett Packard, Fujifilm Dimatix, Konica Minolta and XAAR. They provide print solutions from small to industrial scale printheads, printers, equipments and accessories for the realization of huge variety of application ideas. The inkjet is a versatile, but yet matured technology which finds its use in various application areas e.g. home office documentation, large format posters, variable data printing, security printing, textile printing, wallpapers, household articles, curved surfaces like bottles, printing over edible items, printing of elevated surfaces etc. And, hence there are several literatures published which show the use of the inkjet printing technology in the development of products for printed electronics. Some of the common examples are development of passive and active devices e.g. capacitors, resistors, thin-film-transistors, photovoltaics, sensors, circuits like logic gates for electronic switching, device arrays for detection purposes, point of care health applications, energy harvesting applications etc. But, the exploitation of the inkjet technology has not been intense enough to declare the industrial relevance of the technology to be utilized as a fabrication tool in the market. Meanwhile, all the researchers around the globe aim at a single goal, which is the development of “Proof of Concept” devices and applications. Thus, here in this dissertation the implementation of the inkjet printing technology as a digital fabrication tool is exploited to manufacture and up-scale the printed electronic products, which can show an industrial relevance to the commercial market. The main motivation why printed electronics is in great demand (scientific point of view) and has intensely emerged in the last decades, is because of the primary challenges faced in the fabrication process steps of the µ-electronics society. It is know that the classically fabricated µ-electronic products are in the market since long time due to their high reliability, consistent performance and defined applications in circuitry. But, what cannot be ignored is the involved fabrication steps promote several demerits such as the in-flexibility towards the fabrication process, material wastage, in-ability to up-scale into larger areas and huge quantities, and physical rigidity. Some of these mentioned problems are commonly seen e.g. spin coating, chemical vapor-phase deposition, physical vapor-phase deposition, atomic layer deposition and sputtering fabrication technologies. In this present dissertation, on the contrary, the challenges linked with the manufacturing process of the µ-electronic devices using the inkjet technology are focused and attempts are made to counteract them. Some of the foreseen challenges are: A. process workflow adaptation in device manufacturing; B. validation and evaluation of device performance; C. industrializing the inkjet technology (manufacturing µ-electronics in massive quantities); D. evaluating the fabrication yield of printed devices; D. Generating statistics regarding reliability and scalability; and E. demonstrating tolerances in electronic performances. These are definitely the challenges which must be overcome, and these key research points are addressed in the dissertation.