Environmental analysis of innovative sustainable composites with potential use in aviation sector - A life cycle assessment review

The forecast of growing air transport in the upcoming decades faces the challenge of an increasing environmental impact. Aviation industry is working on promising technologies to mitigate this environmental impact. Lightweight design is a strong lever to lower the fuel consumption and, consequently, with it the emissions of aviation. High performance composites are a key technology to help achieve these aims thanks to their favourable combination of mechanical properties and low weight in primary structures. However, mainly synthetic materials such as petrol based carbon fibres and epoxy resins are used nowadays to produce composite in aviation. Renewable materials like bio-based fibres and resin systems offer potential environmental advantages. However, they have not found their way into aviation, yet. The reasons are reduced mechanical properties and, especially for the use of natural fibres, their flammability. Improvements of these shortcomings are under investigation. Therefore the application of bio-based and recycled materials in certain areas of the aircraft could be possible in the future. Good examples for applications are furnishings and secondary structures. The motivation for this paper is to give an overview of potential environmental properties by using such eco-materials in aviation. Life cycle assessment (LCA) is a tool to calculate environmental impacts during all life stages of a product. The main focus is laid on the bio-fibres flax and ramie, recycled carbon fibres and bio-based thermoset resin systems. Furthermore an overview of environmental aspects of existing composite materials used in aviation is given. Generally, a lack of LCA results for the substitution of synthetic materials by bio-based/recycled composite materials in aviation applications has been identified. Therefore, available information from other transport areas, such as automotive, has been summarized. More detailed LCA data for eco-composite materials and technologies to improve their properties is important to understand potential environmental effects in aviation

Protocole de mise en gage de bit relativiste

National audienceActuellement, la sécurité de la plupart des protocoles cryptographiques repose sur des hy-pothèses calculatoires (factorisation pour RSA, problèmes NP-complets pour les réseaux, loga-rithme discret pour les courbes elliptiques...). Si ces problèmes ne peuvent pas aujourd'hui être résolus efficacement, il n'existe pas non plus de garantie concernant leur difficulté. Face aux progrès algorithmiques et à l'arrivée potentielle d'un ordinateur quantique, plusieurs pistes sont étudiées. L'une d'elles consiste à s'affranchir des hypothèses calculatoires et à les remplacer par des lois physiques. L'objectif de cette approche est de proposer des protocoles sûrs contre tout attaquant, classique ou quantique, même s'il disposait d'une puissance de calcul infinie. Lunghi et al. ont proposé un protocole de mise en gage de bit pour lequel la seule condition de sécurité contre un attaquant classique est l'hypothèse (nécessaire à la cohérence des modèles physiques actuels) selon laquelle il n'est pas possible de transmettre de l'information à une vitesse supérieure à celle de la lumière [LKB + 15]. On parle alors de protocole relativiste. La borne de sécurité de leur protocole a récemment été améliorée (simultanément [FF16] et [CCL15]). Le problème étudié Le protocole de mise en gage de bit proposé dans [LKB + 15] est prouvé sûr contre n'importe quel attaquant classique pour de larges plages de tailles des paramètres (qui sont tout à fait satisfaisants pour une application pratique). Cependant, on ne savait pas si cette borne pouvait encore être améliorée ou non. [PPP16] affirmait avoir trouvé une meilleure borne, mais étaient peu convaincants. Il n'existait pas non plus de résultat concernant sa sécurité face à un attaquant disposant d'une puissance de calcul quantique (c'est-à-dire ni attaque, ni preuve de sécurité). La mise en gage de bit étant une primitive élémentaire qui peut servir de brique dans l'élaboration de constructions plus complexes, si ce protocole pouvait être sûr également face à toute attaque quantique, cela aiderait grandement à la construction de schémas cryptographiques très fiables. J'ai donc cherché à obtenir une borne quelconque (preuve de sécurité ou attaque) concernant la fiabilité du protocole de [LKB + 15] contre un attaquant qui dispose d'un ordinateur quantique

Reining in Expectations in "The Horse-Dealer's Daughter": A New Version of the Pastoral

“The Horse-Dealer’s Daughter” introduces siblings on the brink of profound disruptions in their financial situation. Owing to their father’s mismanagement of his fortune, three brothers are at a crossroads, each resolving to face the new life set before them which involves leaving the family farmhouse and their occupation as horse-dealers. At odds with their resignation, their sister’s transgressive behaviour emphasizes her plea for a freely chosen future even if it implies taking her own lif..

Comment utiliser des algorithmes quantiques pour remplir son sac à dos et décoder des syndromes

As quantum computers become more and more plausible, it is important to redesign cryptography in order to remain secure against this threat. Post-quantum cryptography emerges as an answer to this problem, and has now been widely studied. While many new designs are proposed, there is still a little effort to study the robustness of the underlying computational assumptions against quantum adversaries. In this thesis, I study 2 problems which are important in this context: the knapsack problem and the syndrome decoding problem. For both these problems, I present improved quantum algorithms based on quantum walks and I also discuss the implications for post-quantum cryptography.Les avancées technologiques en matière d'informatique quantique rendent la possibilité d'avoir un ordinateur quantique de plus en plus forte. Il est donc important d'étudier la cryptographie en prenant cette menace en compte, domaine appelé cryptographie post-quantique. De nombreux schéma sont proposés dans ce contexte mais la sécurité quantique des hypothèses calculatoires sous jacentes n'est que peu étudiée. Dans cette thèse j'étudie deux problèmes importants dans ce contexte: le problème du sac-à-dos et le problème de décodage de syndrome. Pour ces deux problèmes, je montre des améliorations quantiques en utilisant des marches quantiques et je présente l'implication de ces résultats pour la cryptographie post-quantique

Improved Classical and Quantum Algorithms for Subset-Sum

We present new classical and quantum algorithms for solving random subset-sum instances. First, we improve over the Becker-Coron-Joux algorithm (EUROCRYPT 2011) from $\tilde{\mathcal{O}}(2^{0.291 n})$ downto $\tilde{\mathcal{O}}(2^{0.283 n})$, using more general representations with values in $\{-1,0,1,2\}$. Next, we improve the state of the art of quantum algorithms for this problem in several directions. By combining the Howgrave-Graham-Joux algorithm (EUROCRYPT 2010) and quantum search, we devise an algorithm with asymptotic cost $\tilde{\mathcal{O}}(2^{0.236 n})$, lower than the cost of the quantum walk based on the same classical algorithm proposed by Bernstein, Jeffery, Lange and Meurer (PQCRYPTO 2013). This algorithm has the advantage of using \emph{classical} memory with quantum random access, while the previously known algorithms used the quantum walk framework, and required \emph{quantum} memory with quantum random access. We also propose new quantum walks for subset-sum, performing better than the previous best time complexity of $\tilde{\mathcal{O}}(2^{0.226 n})$ given by Helm and May (TQC 2018). We combine our new techniques to reach a time $\tilde{\mathcal{O}}(2^{0.216 n})$. This time is dependent on a heuristic on quantum walk updates, formalized by Helm and May, that is also required by the previous algorithms. We show how to partially overcome this heuristic, and we obtain an algorithm with quantum time $\tilde{\mathcal{O}}(2^{0.218 n})$ requiring only the standard classical subset-sum heuristics

D.H. Lawrence: A Bibliography

I. Short stories and novellas by D. H. Lawrence a- 1910-1929 Title. First edition. Standard scholarly edition(s). The Prussian Officer and Other Stories. London: Duckworth, 1914. Ed. John Worthen. Cambridge: Cambridge UP, 1983. Ed. Antony Atkins. Oxford UP, 1995. Print.Contains “The Prussian Officer” (first appeared in the English Review and in Metropolitan in 1914 as “Honour and Arms”), “The Thorn in the Flesh” (first published in the English Review as “Vin Ordinaire” in 1914), “Daughters of..