277 research outputs found
4. Rapports, Etudes et avis des organismes consultatifs
No full textBrimont-Mackowiak Maryse, Georges Franck, Guillemin Philippe, TRAORE Sadio. 4. Rapports, Etudes et avis des organismes consultatifs. In: Annuaire des collectivités locales. Tome 14, 1994. pp. 131-152
Electroconvective Cavity Flow Patterns Created by Asymmetric Electrode Configuration
No full textThis paper is an experimental study on electroconvective flows produced by an asymmetric electric field in a cavity. It is part of a scientific project aiming to develop electrohydrodynamic (EHD) flow actuator in order to enhance heat transfer and mixing efficiency in fluidic and microfluidic systems. In this study, the EHD flow is obtained by applying a dc voltage between two electrodes (cylinder/plane) immersed in a working liquid. The produced velocity fields strongly depend on the applied voltage. Whatever may be the applied voltage, the fluid goes from the cylinder toward the plate or the other way round. The velocity fields obtained by particle image velocimetry for different potentials are analyzed in both cases with the usual mechanisms (injection and conduction) at the origin of the motion of the liquid. A discussion on the transition between injection and conduction phenomena is finally presented.Fil: Louste, Christophe. Université de Poitiers; FranciaFil: Romat, Hubert. Université de Poitiers; FranciaFil: Traore, Philippe. Université de Poitiers; FranciaFil: Daaboul, Michel. University of Balamand; LíbanoFil: Vazquez, Pedro. Universidad de Sevilla; EspañaFil: Sosa, Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentin
Sémio-narrative et typologie de la description dans Kroh ! Les femmes ont déserte la maison de Moussa Traore
No full textRésumé: L’exemplum narratif qui correspond à la structure : (Séq. Argumentative + (séq. narratif) + séq argumentative) depuis l’antiquité trouve son équivalence dans la structure de type (seq. narratif + séq. descriptive + séq. Narrative). La description à cet effet est une séquence qui s’insère dans le flux textuel de la narration que l’on retrouve foisonnante dans Kroh ! Les femmes ont déserté la maison de Moussa TRAORE. Pour ce faire, la sémio-narrative de Philippe HAMON soutenue par Jean Michel ADAM en tandem avec André PETITJEAN est un outil saisissant et motive la formulation du sujet de cet article comme suit : Sémio-narrative et typologie de la description dans Kroh ! Les femmes ont déserté la maison de Moussa TRAORE. Quelle typologie de descriptions existe-t-il dans ce roman ? Et Comment la description s’insère-t-elle dans le roman au moyen d’un actant volubile ? Dans quelle mesure la fluidité spatiale peut-elle ouvrir une séquence de description ? Sur ce, il peut y avoir deux types de descriptions dans l’œuvre. Le type dire qui profite à l’insertion de la description par le biais de la parole savante et le type voir par la fluidité de l’espace qui offre l’objet de la description. L’objectif englobant de cette analyse ambitionne déceler la typologie existante dans le roman de TRORE. Spécifiquement, ce travail vise d’abord à justifier le type dire présent dans le corpus et ensuite le type voir et ses circonstances de description. A la fin de cette analyse, il est notable que le corpus comporte le type dire et le type voir qui s’organisent tous par des syntagmes introducteurs et de fermeture des passages descriptifs pour afin donner sens au texte.
Mots-clés : sémio-narrative, typologie, description, roman, sens
Analysis for Anomalies in Cryptographic RNG and Industrial Applications
No full textDans ce travail, nous analysons des certificats SSL/TLS X.509 (utilisant le chiffrement RSA et provenant de centaines de millions de matériels connectés) à la recherche d'anomalies et étendons notamment les travaux de Hastings, Fried et Heninger (2016). Notre étude a été réalisée sur trois bases de données provenant de l'EFF (2010-2011), de l'ANSSI (2011-2017) et de Rapid7 (2017-2021). Plusieurs vulnérabilités affectant des matériels de fabricants connus furent détectées : modules de petites tailles (strictement inférieures à 1024 bits), modules redondants (utilisés par plusieurs entités), certificats invalides mais toujours en usage, modules vulnérables à l'attaque ROCA ainsi que des modules dits «PGCD-vulnérables» (c'est-à-dire des modules ayant des facteurs communs). Pour la base de données de Rapid7, dénombrant près de 600 millions de certificats (et incluant ceux des matériels récents), nous avons identifié 1,550,382 certificats dont les modules sont PGCD-vulnérables, soit 0.27% du nombre total. Cela a permis de factoriser 14,765 modules de 2048 bits ce qui, à notre connaissance, n'a jamais été fait.En analysant certains modules PGCD-vulnérables, on a pu rétro-concevoir de façon partielle le générateur de modules (de 512 bits) utilisé par certaines familles de pare-feux, ce qui a permis la factorisation instantanée de 42 modules de 512 bits, correspondant aux certificats provenant de 8,817 adresses IPv4.Après avoir constaté que la plupart des modules factorisés avaient été générés par la bibliothèque OpenSSL, on a analysé les codes sources et les méthodes en charge du processus de génération de clefs RSA de plusieurs versions de cette bibliothèque (couvrant la période 2005 à 2021). À travers des expérimentations sur des plateformes à base de processeurs ARM, où l'on s'est mis quasiment dans les mêmes conditions que les matériels vulnérables identifiés, on a réussi à remonter aux causes de la PGCD-vulnérabilité.In this work, we analyze X.509 SSL/TLS certificates (using RSA encryption and from hundreds of millions of connected devices) looking for anomalies and notably extend the work of Hastings, Fried and Heninger (2016). Our study was carried out on three databases from EFF (2010-2011), ANSSI (2011-2017) and Rapid7 (2017-2021). Several vulnerabilities affecting devices from well-known manufacturers were detected: small moduli (strictly less than 1024 bits), redundant moduli (used by several entities), invalid certificates but still in use, moduli vulnerable to the ROCA attack as well as so-called “GCD-vulnerable” moduli (i.e. moduli having common factors). For the Rapid7 database, counting nearly 600 million certificates (and including those for recent devices), we have identified 1,550,382 certificates whose moduli are GCD-vulnerable, that is 0.27% of the total number. This made it possible to factor 14,765 moduli of 2048 bits which, to our knowledge, has never been done.By analyzing certain GCD-vulnerable moduli, we were able to partially reverse-engineer the modulus generator (of 512 bits) used by certain families of firewalls, which allowed the instantaneous factorization of 42 moduli of 512 bits, corresponding certificates from 8,817 IPv4 addresses.After noting that most of the factored moduli had been generated by the OpenSSL library, we analyzed the source codes and the methods in charge of the RSA key generation process of several versions of this library (covering the period 2005 to 2021). Through experiments on platforms based on ARM processors, where we put ourselves in almost the same conditions as the vulnerable devices identified, we managed to trace the causes of the PGCD-vulnerability
Continuous Authentication using Stylometry
No full textStatic authentication, where user identity is checked once at login time, can be circumvented no matter how strong the authentication mechanism is. Through attacks such as man-in-the-middle and its variants, an authenticated session can be hijacked later after the initial login process has been completed. In the last decade, continuous authentication (CA) using biometrics has emerged as a possible remedy against session hijacking. CA consists of testing the authenticity of the user repeatedly throughout the authenticated session as data becomes available. CA is expected to be carried out unobtrusively, due to its repetitive nature, which means that the authentication information must be collectible without any active involvement of the user and without using any special purpose hardware devices (e.g. biometric readers). Stylometry analysis, which consists of checking whether a target document was written or not by a specific individual, could potentially be used for CA. Although stylometric techniques can achieve high accuracy rates for long documents, it is still challenging to identify an author for short documents, in particular when dealing with large author populations.
In this dissertation, we propose a new framework for continuous authentication using authorship verification based on the writing style. Authorship verification can be checked using stylometric techniques through the analysis of linguistic styles and writing characteristics of the authors. Different from traditional authorship verification that focuses on long texts, we tackle the use of short messages. Shorter authentication delay (i.e. smaller data sample) is essential to reduce the window size of the re-authentication period in CA. We validate our method using different block sizes, including 140, 280, and 500 characters, and investigate shallow and deep learning architectures for machine learning classification. Experimental evaluation of the proposed authorship verification approach based on the Enron emails dataset with 76 authors yields an Equal Error Rate (EER) of 8.21% and Twitter dataset with 100 authors yields an EER of 10.08%. The evaluation of the approach using relatively smaller forgery samples with 10 authors yields an EER of 5.48%.Graduat
A robust iterative scheme for finite volume discretization of diffusive flux on highly skewed meshes
No full textAbstractA new approach for diffusive flux discretization on a nonorthogonal mesh for finite volume method is proposed. This approach is based on an iterative method, Deferred correction introduced by M. Peric [J.H. Fergizer, M. Peric, Computational Methods for Fluid Dynamics, Springer, 2002]. It converges on highly skewed meshes where the former approach diverges. A convergence proof of our method is given on arbitrary quadrilateral control volumes. This proof is founded on the analysis of the spectral radius of the iteration matrix. This new approach is applied successfully to the solution of a Poisson equation in quadrangular domains, meshed with highly skewed control volumes. The precision order of used schemes is not affected by increasing skewness of the grid. Some numerical tests are performed to show the accuracy of the new approach
Long-term virological, immunological and mortality outcomes in a cohort of HIV-infected female sex workers treated with highly active antiretroviral therapy in Africa.
No full textBACKGROUND: Concerns have been raised that marginalised populations may not achieve adequate compliance to antiretroviral therapy. Our objective was to describe the long-term virological, immunological and mortality outcomes of providing highly active antiretroviral therapy (HAART) with strong adherence support to HIV-infected female sex workers (FSWs) in Burkina Faso and contrast outcomes with those obtained in a cohort of regular HIV-infected women. METHODS: Prospective study of FSWs and non-FSWs initiated on HAART between August 2004 and October 2007. Patients were followed monthly for drug adherence (interview and pill count), and at 6-monthly intervals for monitoring CD4 counts and HIV-1 plasma viral loads (PVLs) and clinical events. RESULTS: 95 women, including 47 FSWs, were followed for a median of 32 months (interquartile range [IQR], 20-41). At HAART initiation, the median CD4 count was 147 cells/μl (IQR, 79-183) and 144 cells/μl (100-197), and the mean PVLs were 4.94 log10 copies/ml (95% confidence interval [CI], 4.70-5.18) and 5.15 log10 copies/ml (4.97-5.33), in FSWs and non-FSWs, respectively. Four FSWs died during follow-up (mortality rate: 1.7 per 100 person-years) and none among other women. At 36 months, the median CD4 count increase was 230 cells/μl (IQR, 90-400) in FSWs vs. 284 cells/μl (193-420) in non-FSWs; PVL was undetectable in 81.8% (95% CI, 59.7-94.8) of FSWs vs. 100% (83.9-100) of non-FSWs; and high adherence to HAART (> 95% pills taken) was reported by 83.3% (95% CI, 67.2-93.6), 92.1% (95% CI, 78.6-98.3), and 100% (95% CI, 54.1-100) of FSWs at 6, 12, and 36 months after HAART initiation, respectively, with no statistical difference compared to the pattern observed among non-FSWs. CONCLUSIONS: Clinical and biological benefits of HAART can be maintained over the long-term among FSWs in Africa and could also lead to important public health benefits
Pour une lisibilité du rôle des femmes au travers des données statistiques
No full textA l'aide d'exemples choisis principalement en Cote d'Ivoire, les auteurs passent en revue les domaines où la mauvaise qualité des données est préjudiciable à une juste appréciation du rôle économique des femmes. Des erreurs entachent le dénombrement de la population féminine, le taux d'activité de la population féminine est souvent sous évalué, les données recueillies sur la fécondité et les besoins de santé et la planification familiale sont insuffisantes. La mauvaise appréciation du rôle économique des femmes compromet l'avenir des plans de développement
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