Robust control tools for traffic monitoring in TCP/AQM networks

Several studies have considered control theory tools for traffic control in communication networks, as for example the congestion control issue in IP (Internet Protocol) routers. In this paper, we propose to design a linear observer for time-delay systems to address the traffic monitoring issue in TCP/AQM (Transmission Control Protocol/Active Queue Management) networks. Due to several propagation delays and the queueing delay, the set TCP/AQM is modeled as a multiple delayed system of a particular form. Hence, appropriate robust control tools as quadratic separation are adopted to construct a delay dependent observer for TCP flows estimation. Note that, the developed mechanism enables also the anomaly detection issue for a class of DoS (Denial of Service) attacks. At last, simulations via the network simulator NS-2 and an emulation experiment validate the proposed methodology

Design and performance evaluation of a state-space based AQM

Recent research has shown the link between congestion control in communication networks and feedback control system. In this paper, the design of an active queue management (AQM) which can be viewed as a controller, is considered. Based on a state space representation of a linearized fluid flow model of TCP, the AQM design is converted to a state feedback synthesis problem for time delay systems. Finally, an example extracted from the literature and simulations via a network simulator NS (under cross traffic conditions) support our study

Utilisation d'un algorithme d'interpolation de données irrégulièrement réparties pour l'estimation et la compensation de mouvement dans une séquence d'images

Dans ce papier, nous présentons une nouvelle modélisation du mouvement. Cette modélisation est issue d'une technique d'interpolation à partir d'échantillons irréguliers. Elle permet à partir d'un nombre limité de vecteur-échantillons de construire un champ dense de vecteurs. L'optimisation des paramètres liés aux vecteur-échantillons conduit à un champ dense de vecteurs minimisant l'erreur de compensation. Des résultats en terme de qualité de compensation en mouvement et en terme de codage sont donnés

20 ans de comparaison France-Allemagne : de l'effet sociétal à l'analyse de l'articulation des régulations globales et locales

International audienceNous proposons de mettre au centre de la comparaison internationale les niveaux de décision et en particulier leur articulation. Cela suppose d'abandonner les visions stéréotypées qui rangent d'emblée les faits observés, soit du côté des régulations globales (sociétales ou autres) soit du côté des décisions locales. Il s'agit en effet de renoncer aux explications " totalisantes ". L'objet de la comparaison devient l'analyse des interdépendances entre décisions locales et globales. L'exemple de la négociation du temps de travail montre comment les différents niveaux de décisions interagissent. La loi définit certes le cadre des négociations, mais ce cadre est ensuite retravaillé au niveau de la branche, et au niveau de l'entreprise. La France et l'Allemagne se distinguent alors non seulement par l'existence de régulations globales différentes, aboutissant d'un côté à des lois et de l'autre côté à des conventions collectives, mais aussi par des articulations différentes des régulations globales et locales.Malgré les différences, il nous semble alors que la question de l'emploi et sa traduction en différents types de régulations intermédiaires, permettent de relancer le débat sur la convergence de ces deux sociétés

Floating polygon soup

International audienceThis paper presents a new representation called floating polygon soup for applications like 3DTV and FTV (Free Viewpoint Television). This representation is based on 3D polygons and takes as input MVD data. It extends the previously proposed polygon soup representation which is appropriate for both compression, transmission and rendering stages. The floating polygon soup conserves these advantages while also taking into account misalignments at the view synthesis stage due to modeling errors. The idea for reducing these misalignments is to morph the 3D geometry depending on the current viewpoint. Results show that artifacts in virtual views are reduced and objective quality is increased

Fluctuation characteristics of the TCV snowflake divertor measured with high speed visible imaging

Tangentially viewing fast camera footage of the low-field side snowflake minus divertor in TCV is analysed across a four point scan in which the proximity of the two X-points is varied systematically. The motion of structures observed in the post- processed movie shows two distinct regions of the camera frame exhibiting differing patterns. One type of motion in the outer scrape-off layer remains present throughout the scan whilst the other, apparent in the inner scrape-off layer between the two nulls, becomes increasingly significant as the X-points contract towards one another. The spatial structure of the fluctuations in both regions is shown to conform to the equilibrium magnetic field. When the X-point gap is wide the fluctuations measured in the region between the X-points show a similar structure to the fluctuations observed above the null region, remaining coherent for multiple toroidal turns of the magnetic field and indicating a physical connectivity of the fluctuations between the upstream and downstream regions. When the X-point gap is small the fluctuations in the inner scrape-off layer between the nulls are decorrelated from fluctuations upstream, indicating local production of filamentary structures. The motion of filaments in the inter-null region differs, with filaments showing a dominantly poloidal motion along magnetic flux surfaces when the X-point gap is large, compared to a dominantly radial motion across flux-surfaces when the gap is small. This demonstrates an enhancement to cross-field tranport between the nulls of the TCV low-field-side snowflake minus when the gap between the nulls is small.Comment: Accepted for publication in Plasma Physics and Controlled Fusio

Compact quad-based representation for 3D video

International audienceThe context of this study is 3D video. Starting from a sequence of multi-view video plus depth (MVD) data, the proposed quad-based representation takes into account, in a unified manner, different issues such as compactness, compression, and intermediate view synthesis. The representation is obtained into two steps. Firstly, a set of 3D quads is extracted by using a quadtree decomposition of the depth maps. Secondly, a selective elimination of the quads is performed in order to reduce inter-view redundancies and thus provide a compact representation. Experiments on two real sequences show good quality results at the rendering stage and a small data overload compared to mono-view video

Moms Support Group: Lack of Support to Moms Postpartum

This service learning project is centered on organizing and running a mom support group regularly to provide moms with the chance to assist one another in a safe atmosphere for their recovery following childbirth. Additionally, I created a social media page on the platform found on Instagram for this support group so that moms may communicate frequently and follow and interact to join for upcoming events. The project will benefit the moms by helping them make more meaningful connections and feel more supported during this time. Navigating parenting while maintaining all aspects of your life can be difficult. Going through similar experiences and getting assistance from others has proven helpful