Interaction Fluide-Structure pour les problèmes de dynamique rapide

National audienceLa dynamique rapide regroupe des phénomènes physiques en grande déformation de courte durée impliquant généralement un fluide et une structure. Le crash, le développement d’un airbag, le tossage d’un navire sont autant d’exemples d’interaction fluide-structure spectaculaires de l’ordre de quelques millisecondes. La simulation numérique a beaucoup apporté à la compréhension de ces phénomènes physiques. Cependant la complexité des simulations numériques actuelles, en dynamique rapide, conduit encore à des problèmes liés au temps de calcul et implicitement aux maillages utilisés pour décrire les géométries. Les grandes déformations impliquent un traitement spécial du maillage. Certaines approches s’affranchissent de la connectivité comme la méthode SPH. D’autres remaillent le domaine de calcul. Ici nous nous intéresserons à la formulation ALE (Arbitrary Lagrange Euler) et, à titre d’illustration, nous l’appliquerons à l’impact hydrodynamique d’un dièdre

ICT intensity of use and the geography of firms

This paper investigates the relationship between the geography of firms and the intensity of use of information and communication technologies (ICTs). Our approach to the geography of firms is multifaceted, in relation to the various characteristics of their location area(s), to their organisational fragmentation, and to their spatial organisation at a national scale. Making use of a single cross-section dataset drawn from the ‘ICT and e-commerce’ survey for the French industry, we examine firms’ decisions to use the Internet more or less intensively. We find that firms’ internal fragmentation lead to important variations in the intensity of Internet use. Moreover, we find that firms benefit from urbanisation economies through the location of their headquarters and also through that of their units in the case of multiunit firms. Finally, we observe a strong positive effect of competitive pressure at both national and international levels as well as geographical and sectoral epidemic effects on the intrafirm diffusion of the Internet.

Air blast reflecting on a rigid cylinder: simulation and reduced scale experiments

International audienceIn this paper, the Multi-Material ALE formulation is applied to simulate the propagation of an air blast through the atmosphere, and its reflection on an assumed rigid cylindrical obstacle. The mathematical and numerical implementations of this formulation are presented. In order to validate the formulation and prove its ability to capture the propagation and reflection of high pressure waves, comparisons of the simulations with the experimental blast pressure measured on an assumed rigid cylinder are performed. The simulation conducted via the presented models and methods gives good predictions for pressure time histories recorded on the rigid cylinder

GNSS location verification in connected and autonomous vehicles using in-vehicle multimodal sensor data fusion

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Connected and Autonomous Vehicles (CAVs) rely on Global Navigation Satellite Systems (GNSS), e.g., the Global Positioning System (GPS), for the provision of accurate location information for various functionalities including Vehicle-to-Vehicle/Infrastructure (V2V/V2I) communication and self-navigation. However, GNSS- based location awareness is prone to spoofing attacks, where the attacker generates counterfeit satellite signals. This in turn poses a serious threat to the CAV, e.g., car, drone, etc., as well as the surrounding entities. Thus, this threat needs to be detected reliably and mitigated timely to prevent undesired consequences (e.g., damages, casualties, etc.). To this end, this work proposes a location verification solution that leverages in-vehicle sensor readings (e.g., accelerometer, etc.) and Signals of Opportunity (SoO), as an alternative source of location information. In particular, the multimodal sensor data with SoO location measurements are fused by means of a Kalman filter and the estimated fusion-based location is used to verify the location output of the GPS receiver. In case the GPS location deviates considerably from the fusion-based location, then a location spoofing attack is ascertained. Preliminary experimental results with real GPS and sensor data collected with a drone demonstrate the effectiveness of the proposed approach.Peer ReviewedPostprint (published version

Diagnosis and antimicrobial treatment of invasive infections due to multidrug-resistant Enterobacteriaceae. Guidelines of the Spanish Society of Infectious Diseases and Clinical Microbiology

<p>The spread of multidrug-resistant Enterobacteriaceae related to the production of extended-spectrum β-lactamases and carbapenemases is a serious public health problem worldwide. Microbiological diagnosis and therapy of these infections are challenging and controversial. Clinically relevant questions were selected and the literature was reviewed for each of them. The information from the selected articles was extracted and recommendations were provided and graded according to the strength of the recommendations and quality of the evidence. The document was opened to comments from the members from the Spanish Society of Infectious Diseases and Clinical Microbiology, which were considered for inclusion in the final version. Evidence-based recommendations are provided for the use of microbiological techniques for the detection of extended-spectrum β-lactamases and carbapenemases in Enterobacteriaceae, and for antibiotic therapy for invasive/severe infections caused by these organisms. The absence of randomised controlled trials is noteworthy; thus, recommendations are mainly based on observational studies (that have important methodological limitations), pharmacokinetic and pharmacodynamics models, and data from animal studies. Additionally, areas for future research were identified.</p&gt