Decentralized High Level Controller for Formation Flight Control of UAVs

International audienceThe main contribution of this paper is the design of a decentralized and tuning-less high level controller able to maintain without tracking errors a Leader-Follower (LF) configuration in case of lack or degraded communications (latencies, loss…) between the leader and followers UAVs. The high level controller only requires simple tunings and rests on a predictive filtering algorithm and a first order dynamic model to recover an estimation of the leader UAV velocities and avoid the tracking errors

My Way or the Highway: a More Naturalistic Model of Altruism Tested in an Iterative Prisoners' Dilemma

There are three prominent solutions to the Darwinian problem of altruism, kin selection, reciprocal altruism, and trait group selection. Only one, reciprocal altruism, most commonly implemented in game theory as a TIT FOR TAT strategy, is not based on the principle of conditional association. On the contrary, TIT FOR TAT implements conditional altruism in the context of unconditionally determined associates. Simulations based on Axelrod\'s famous tournament have led many to conclude that conditional altruism among unconditional partners lies at the core of much human and animal social behavior. But the results that have been used to support this conclusion are largely artifacts of the structure of the Axelrod tournament, which explicitly disallowed conditional association as a strategy. In this study, we modify the rules of the tournament to permit competition between conditional associates and conditional altruists. We provide evidence that when unconditional altruism is paired with conditional association, a strategy we called MOTH, it can out compete TIT FOR TAT under a wide range of conditions.Game Theory; Altruism; Prisoners' Dilemma; TIT FOR TAT; MOTH; Docking; Netlogo

SAGETTARIUS: a program to reduce the number of tags mapped to multiple transcripts and to plan SAGE sequencing stages

SAGE (Serial Analysis of Gene Expression) experiments generate short nucleotide sequences called ‘tags’ which are assumed to map unambiguously to their original transcripts (1 tag to 1 transcript mapping). Nevertheless, many tags are generated that do not map to any transcript or map to multiple transcripts. Current bioinformatics resources, such as SAGEmap and TAGmapper, have focused on reducing the number of unmapped tags. Here, we describe SAGETTARIUS, a new high-throughput program that performs successive precise Nla3 and Sau3A tag to transcript mapping, based on specifically designed Virtual Tag (VT) libraries. First, SAGETTARIUS decreases the number of tags mapped to multiple transcripts. Among the various mapping resources compared, SAGETTARIUS performed the best in this respect by decreasing up to 11% the number of multiply mapped tags. Second, SAGETTARIUS allows the establishment of a guideline for SAGE experiment sequencing efforts through efficient mapping of the CRT (Cytoplasmic Ribosomal protein Transcripts)-specific tags. Using all publicly available human and mouse Nla3 SAGE experiments, we show that sequencing 100 000 tags is sufficient to map almost all CRT-specific tags and that four sequencing stages can be identified when carrying out a human or mouse SAGE project. SAGETTARIUS is web interfaced and freely accessible to academic users

Central activation after chronic vagus nerve stimulation in pigs : contribution of functional imaging

Chronic vagus nerve stimulation (VNS), used to treat refractory epilepsy, has the potential to alter food intake in animals and humans. The aim of our study was to evaluate the impact of VNS on the feeding behaviour of pigs used as a human model, and to investigate the origin of its potential effects. Food intake was significantly decreased after five weeks of chronic VNS. This reduction was not due to stimulation of the vagus efferents as neither gastric compliance nor gastric emptying was altered. VNS triggered a reorganisation of brain activation, probably via subcortical structures involved in the reward mechanism. The activation of the olfactory bulb during VNS is probably one of the mechanisms responsible for the drastic changes in food preference in favour of lipids.La stimulation vagale chronique (VNS), une thérapeutique de l'épilepsie pharmacorésistante, serait capable chez l'animal et chez l'homme de modifier le comportement alimentaire. Le but de notre étude était de préciser l'impact de la VNS sur le comportement alimentaire du porc pris comme modèle de l'homme et d'étudier l'origine de ses effets potentiels. La VNS conduit au bout de cinq semaines à une réduction de la quantité d'aliment ingéré. Cette réduction n'est pas la conséquence de la stimulation des efférences vagales, la compliance ou l'évacuation de l'estomac, n'étant pas modifiée. Par contre, la VNS provoque une réorganisation de l'activation cérébrale mettant vraisemblablement en jeu les structures sous-corticales impliquées dans le processus de récompense. L'activation du bulbe olfactif au cours de la VNS est probablement l'un des éléments à l'origine des modifications drastiques des préférences alimentaires en faveur des lipides

Monitoring elderly activities at home

International audienceThe elderly population is expected to grow dramatically over the next 20 years. As people grow older, they need more healthcare assistance. Without receiving sufficient care, elderly are at risk of loosing their autonomy. Thus a system permitting elderly to live safely at home is more than needed. Medical professionals believe that one of the best ways to detect emerging physical and mental health problems (before it becomes critical – particularly for the elderly) is to look for changes in their activities of daily living (ADLs). For this purpose, we propose a monitoring system which aims at detecting activities of daily living (ADLs) at home

Coherent multi-layer landscape synthesis

We present an efficient method for generating coherent multi-layer landscapes. We use a dictionary built from exemplars to synthesize high-resolution fully featured terrains from input low-resolution elevation data. Our example-based method consists in analyzing real-world terrain examples and learning the procedural rules directly from these inputs. We take into account not only the elevation of the terrain, but also additional layers such as the slope, orientation, drainage area, the density and distribution of vegetation, and the soil type. By increasing the variety of terrain exemplars, our method allows the user to synthesize and control different types of landscapes and biomes, such as temperate or rain forests, arid deserts and mountains.Peer ReviewedPostprint (author's final draft

Dual-Multiphase Motor Drives for Fault- Tolerant Applications: Power Electronic Structures and Control Strategies

This paper analyzes two fault-tolerant dualmultiphase motor drives, a series connected topology and a standard H-bridge topology. Previous studies have shown that the series connected topology is appropriate to an aerospace application and has lower peak current in degraded mode in comparison with the H-bridge topology, which may consequently diminish the system’s weight and cost. This paper extends the study to compare different control strategies of these structures under two fault conditions: short-circuit of an inverter’s switch and an open-phase of the machine. The control strategies analyzed in this paper do not impact the fundamental current or the torque generation, but the amplitudes of some harmonics in degraded mode are expected to be narrowed down in order to reduce the inverter’s size. Some analyses of maximum voltage and peak current in degraded mode have been used for inverter dimensioning. Experimental results are shown and compared to the simulated ones to confirm the validity of this study.Thales Avionics Electrical System

Commande en Mode Dégradé d’un Drive avec Deux Machines 6 phases en Série

Dans le cadre d’une commande en mode dégradé d’un entrainement comprenant deux machines polyphasées connectées en série et pilotées de façon indépendante, l’article s’intéresse à analyser la performance de l’entrainement dans le cas d’un défaut de court-circuit d’un transistor. Deux reconfigurations modifiant l’algorithme de commande ont été présentées avec les objectifs d’éliminer l’ondulation de couple et de comparer la valeur de courant crête obtenue avec chaque stratégie en vue d’obtenir un dimensionnement de l’entrainement au plus juste.Thales Grou