Disrupting Daesh: measuring takedown of online terrorist material and its impacts

This report seeks to contribute to public and policy debates on the value of social media disruption activity with respect to terrorist material. We look in particular at aggressive account and content takedown, with the aim of accurately measuring this activity and its impacts. Our findings challenge the notion that Twitter remains a conducive space for Islamic State (IS) accounts and communities to flourish, although IS continues to distribute propaganda through this channel. However, not all jihadists on Twitter are subject to the same high levels of disruption as IS, and we show that there is differential disruption taking place. IS’s and other jihadists’ online activity was never solely restricted to Twitter. Twitter is just one node in a wider jihadist social media ecology. We describe and discuss this, and supply some preliminary analysis of disruption trends in this area

Microstructure and photocatalytic activity of APS coatings obtained from different TiO2 nanopowders

In recent years, intense research has shown that thermal spray techniques, especially atmospheric plasma spraying (APS), can be used to obtain nanostructured TiO2 coatings with effective photocatalytic activity. This study compares the photocatalytic activity of APS coatings obtained from different powders: two nanostructured TiO2 powders produced by spray-drying of two TiO2 nanosuspensions with different solids contents, one spray-dried powder obtained from a suspension comprising a mixture of submicronic and nanometric TiO2 particles and finally one commercial, nanostructured, TiO2 spray-dried powder. All powders were characterised by XRD, FEG-ESEM, granule size distribution, and a flowability evaluation. Feedstock powders were then deposited on austenitic stainless steel coupons using APS. Hydrogen or helium was used as secondary plasma gas. Coating microstructure and phase composition were characterised using FEG-ESEM and XRD techniques; coating anatase content was quantified by the Rietveld method. A significant amount of anatase to rutile transformation was found to take place during the plasma spraying process. In general, the coatings had a bimodal microstructure characterised by the presence of completely fused areas in addition to non-molten areas consisting of agglomerates of anatase nanoparticles. Results also showed that anatase content and porosity of the coatings largely depend on the secondary plasma gas nature, as well as on the characteristics of the feedstock. Finally the photocatalytic activity of the coatings was determined by measuring the degradation of methylene blue dye in an aqueous solution. A reasonably good fit of a first-order kinetic model to the experimental data was found for all coatings. The values of the kinetic constant were related to feedstock characteristics as well as to plasma spraying conditions. (C) 2012 Elsevier B.V. All rights reserved.Bordes, MC.; Vicent, M.; Moreno, A.; Moreno, R.; Borrell Tomás, MA.; Salvador Moya, MD.; Sanchez, E. (2013). Microstructure and photocatalytic activity of APS coatings obtained from different TiO2 nanopowders. Surface and Coatings Technology. 220:179-186. doi:10.1016/j.surfcoat.2012.08.059S17918622

Effect of particle size distribution of suspension feedstock on the microstructure and mechanical properties of suspension plasma spraying YSZ coatings

In this work, aqueous suspension feedstocks with different particle size distribution from submicron- and nanosized YSZ powders were prepared. A previous colloidal characterisation allowed concentrated suspensions (~40 wt%) to be prepared. These suspensions were then successfully deposited by suspension plasma spraying (SPS) onto stainless steel substrates at different spraying distances. Coatings were characterised in terms of microstructure and mechanical properties (hardness and elastic modulus) by nanoindentation. All coatings displayed a two-zone microstructure formed by partially melted areas containing nanometre or submicrometre-sized particles surrounded by fully melted areas. These partially melted areas strongly increased as standoff distance lengthened. Mechanical properties worsened with spraying distance increase. The finer the feedstock particle size the more the spraying distance effect was. A clear correlation between mechanical properties and amount of partially melted areas has been proved. Thus the use of a mixture of nano/submicron-sized particles as a SPS feedstock can represent a good balance between suspension processability and final coating performance.This work has been supported by the Spanish Ministry of Science and Innovation and by ERDF (European Regional Development Funds) (Project MAT2012-38364-C03). The authors also acknowledge the SCSIE of the University of Valencia for the FEG-SEM observations. Finally, the Research Promotion Plan of the Universitat Jaume I, action 3.1 (ref. PREDOC/2009/10) and the Spanish Ministry of Science and Innovation for Juan de la Cierva contract (JCI-2011-10498) is also grateful.Carpio, E.; Bannier, E.; Salvador Moya, MD.; Borrell Tomás, MA.; Moreno, R.; Sánchez, E. (2015). Effect of particle size distribution of suspension feedstock on the microstructure and mechanical properties of suspension plasma spraying YSZ coatings. Surface and Coatings Technology. 268:293-297. https://doi.org/10.1016/j.surfcoat.2014.08.063S29329726

Les îles Heimaey et Surtsey de l'archipel volcanique Vestmannaejar (Islande). Étude du littoral

SUMMARY Since its very recent appearance (1963), Surtsey has evolved in such a way as to throw light on the formation of the others islands in the archipelago. A comparative study of a stabilized island (Heimaey) and a forming shorelin (Surlsey) makes it possible to estimate the effect of the sea. The evolution has been very swift. Basalt cliffs have receded over 100 m in one year. Pebble beachs have croped up in less than a year. In a very short lime (a maximum of five years) these pebbles have become quite rounded. An equilibrium may soon be reached. The shore of Heimaey looks stable. From then on, the sea produces but little effect on seashore.RÉSUMÉ L'évolution de Surtsey , depuis sa date de naissance (1963), permet d'expliquer la formation des autres îles de l'archipel. Grâce à l'étude comparative d'une île stabilisée (Heimaey) et d'un littoral en voie de formation (Surtsey), on peut évaluer le rôle et la valeur de l'action marine. L'évolution est très rapide. Des falaises de basalte ont reculé de 100 mètres en une année. Des cordons de galets ont été mis en place en moins d'un an. Les galets, pendant un temps très court (au maximum 5 ans), ont acquis un excellent émoussé. Il est possible qu'un état d'équilibre s'établisse rapidement. Les côtes d'Heimaey semblent stabilisées. Dès lors, la mer n'a plus qu'une action réduite sur le littoral.Moign Y., Moign Annik. Les îles Heimaey et Surtsey de l'archipel volcanique Vestmannaejar (Islande). Étude du littoral. In: Norois, n°67, Juillet-Septembre 1970. pp. 305-334

Analyse, modélisation et réduction du bruit de commutation simultanée généré par les interfaces d’entrées/sorties haute vitesse dans les microcontrôleurs STM32

This thesis has been realized within the framework of a Cifre agreement between the laboratory Polytech’lab and the STMicroelectronics company and relates to the field of electromagnetic compatibility (EMC). The quick and perpetual evolution of the microcontroller (MCU) leads to an important degradation of their behavior regarding the CEM. For example, the Simultaneous Switching Noise (SSN) is a subject known since the 80s but became a source of failure through the years because of, among other things, the increase of communication frequency. This thesis is focused on the study of this SSN effect in the constrained environment of the STM32. A modelling methodology of a complete system defined by the die, the package, and the Printed Circuit Board (PCB) has been validated by an important procedure of comparison between simulations and measurements. These simulations allow, on one hand, to study a failed product and to analyze the failure origin and on the other hand, to observe the SSN effect to points that are physically unreachable in measurement. The Power Distribution Network (PDN) has been identified as the main propagation vector for SSN. A very important stage of modelling, both of the printed board, of the package and of the integrated circuit itself has been carried out. This work permits to define the main design rules applied to the chip, the package, and the PCB in purpose to improve the MCU robustness regarding the SSN effect. To conclude, this thesis presents a new work approach for designers with the development of a predictive model. This predictive model allows the anticipation of the future MCU behavior regarding EMC problematic and this, directly from the design phase. Knowing the very fast evolution of the CMOS technology and therefore of the MCU, being able to anticipate these problems is a real advantage in purpose to be competitive on the market with more robust and reliable products.Cette thèse réalisée dans le cadre d’une convention Cifre entre le laboratoire Polytech’Lab et la société STMicroelectronics, porte sur le domaine de la compatibilité électromagnétique (CEM). L’évolution perpétuelle et très rapide des microcontrôleurs (MCU) implique une dégradation importante de leur comportement vis-à-vis de la CEM. Par exemple, le bruit à commutation simultanée (BCS), connu depuis les années 80, est devenu une source de défaillance du MCU en raison notamment de l’augmentation des fréquences de communication. Cette thèse s’inscrit dans l’étude de ce phénomène au sein de l’environnement très contraint du microcontrôleur STM32. Une méthode de modélisation d’un système complet puce/boîtier/circuit imprimé a été validée par une importante procédure de comparaison entre mesures et simulations. Ces dernières permettent de pouvoir, d’une part étudier la défaillance d’un produit, en analysant leurs principales défaillances, et d’autre part observer l’effet du BCS à des endroits physiquement inatteignables en mesure. Le réseau de distribution des alimentations ou PDN (Power Distribution Network) a été identifié comme le principal vecteur de propagation du bruit BCS. Une étape très importante de modélisation, à la fois de la carte imprimée, du boîtier et du circuit intégré lui-même a été réalisée. Ce travail a permis de définir les principales règles de conception appliquées sur la puce, le boitier et le circuit imprimé pour améliorer la robustesse du MCU au bruit BCS. Pour conclure, nous avons présenté une nouvelle approche de travail avec le développement d’un modèle prédictif permettant l’anticipation du comportement d’un futur MCU face aux problèmes de CEM, et cela, dès la phase de conception. Connaissant l’évolution très rapide de la technologie CMOS et des MCU, réussir à anticiper ces problèmes est un réel avantage pour pouvoir rester compétitif sur le marché avec des produits plus robustes et fiables

Les mesures de protection du littoral en France

Moign Annik. Les mesures de protection du littoral en France. In: Cahiers du Centre nantais de recherche pour l'aménagement régional, n°13, 1977. Actes du colloque sur L'aménagement du littoral, Nantes, décembre 1976. pp. 11-19

Formes sous-marines et littorales de la Baie du Roi (Spitsberg). Méthodes d'étude, aspects et problèmes

Moign Annik. Formes sous-marines et littorales de la Baie du Roi (Spitsberg). Méthodes d'étude, aspects et problèmes . In: Bulletin de l'Association de géographes français, N°342-343, 43e année, Mars-avril 1966. pp. 11-24