Cluster-based Routing Protocols for Energy-Efficiency in Wireless Sensor Networks

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Calibration automatique de modèles hydrodynamiques de rivière basés sur le logiciel bidimensionnel HYDRO-AS_2D

RÉSUMÉ La modélisation numérique occupe une place de plus en plus importante dans le travail de l’ingénieur hydraulicien. Les avancées en matière de vitesse de calculs ont démocratisé l’utilisation de modèles hydrodynamiques 2D par volumes finis. Toutefois, afin d’offrir une bonne capacité prédictive, ces modèles doivent êtres calibrés.----------ABSTRACT Numerical modelling is an increasingly important part of a hydraulic engineer’s job. Faster computer calculations have widened access to 2D hydrodynamic models. However, in order to maintain adequate predictive capabilities, these models need to be properly calibrated

Effect of age and sex on echocardiographic left ventricular diastolic function parameters in patients with preserved ejection fraction and normal valvular function

Background: We conducted a retrospective study to specify the effect of age and gender on echocardiographic left ventricular diastolic function parameters.Methods: We included echocardiograms done in our institution between 1995 and 2007, for which data on diastolic function were available. In order to target a population as close aspossible to healthy subjects, echocardiograms reporting abnormal contraction, valvulopathy or extreme data were excluded.Results: A total of 14,298 patients (mean age 58.53 years; men 49.1%) were included in the study. Sex did not influence E/A ratio (p = 0.298) but age decreased it significantly (p < 0.001). E/e ratio increased significantly with age (p < 0.001) and was higher in women than in men (p < 0.001). After the age of 40, more than 10% of the patients had an E/e ratio superior than 8.Conclusions: To our knowledge, this is the most imposing study — in terms of number of patients from first to tenth decade of life that were included — addressing the effect of age and gender on diastolic function. Our results stress the need for future prospective trials to establishnormal diastolic function parameters according to age and gender, notably for the E/e ratio for which a significant proportion of our population had a ratio superior of what is actually considered normal

Commande visuelle et orale d'un robot mobile

National audienceLe but de ce papier est de présenter une interface de commande multimodale d'un robot mobile distant, équipé d'une caméra orientable en direction et azimut. Les modalités utilisées sont le regard associé à la parole ou au geste. Le champ d'applications que permet d'envisager le démonstrateur réalisé couvre des domaines variés, télésurveillance, handicap moteur, exploration de sites hostiles ou inaccessibles. Cet article décrit l'architecture matérielle, l'architecture logicielle et les différents protocoles de communication mis en oeuvre sur une plateforme démonstrative réalisée dans le cadre d'une collaboration régionale entre des équipes du CRAN et du LORIA

Analysing End-to-End Packet Delay and Loss in mobile ad hoc networks for interactive audio applications

Colloque avec actes et comité de lecture. nationale.National audienceInteractive audio applications such as audio conferencing and telephony require high constraints on delay, jitter and loss. The packets of these applications must be received without significant loss, with low delay and jitter. When packet loss rate exceeds 10% and one way delay exceeds 150 ms, speech quality can be quite poor. Human conversation tolerates a maximum end-to-end delay of between 150 and 300 milliseconds. In addition, these packets must have a small delay variation to maintain constant rate for successive audio packets at the destination. In ad hoc networks, many factors such load traffic, codec bit rate, routing protocol configuration and mobility speed have an impact on packet loss rate, delays, and jitter which degrade the quality of the received audio signal. In this paper, we analysed how these factors influence packet delay and loss observed at the reciever side. A best knowledge of this behaviour is important to develop more effective mechanisms for dynamic adjustment of playout delays or throughput, in order to improve the perceptual quality of audio applications running in ad hoc networks. At the receiver side, we distinguish two operating phases of an audio flow, normal phase and reconfiguration phase. During a normal phase the flow reaches the destination from the source on the same route without link breakage, while during a reconfiguration phase, nodes move on the current route and the audio flow transfer is interrupted for delay required from a routing protocol to establish a new route towards the destination

TOMAC-WSN: A new WSN efficient protocol for monitoring big distributed mechanical systems

International audienceThis paper addresses a wireless sensor network dedicated to monitor a large mechanical system. The chosen system for the scenario is a chairlift. In this case the wireless sensor network special feature is the mobility of nodes following an invariant path traveled repeatedly. A sensor node is put on each chair and a sink node is at ground at the upper end of the chairlift. A new protocol called TOMAC-WSN is designed in order to schedule frames transmission using token concept. This avoids collision at the medium access. The second concept used by TOMAC-WSN is frame aggregation. This new protocol has been modelled using Finite State Automata. An experimental implementation on Arduino boards shows the correct operation of the network. Network performance in terms of delivery time and packet loss rate is evaluated using simulation. The results show that the proposed TOMAC-WSN protocol delivers the appropriate quality of service for the monitoring of large physical systems

Multi-image flock size estimation with CountEm: A casestudy with half a million Common Eiders and Greater Snow Geese

Many of the methods used for estimating population size from ecological surveys have limitations on precision, cost, and/or applicability. The CountEm method was proposed recently for estimating the number of individuals in large groups from single images. It is simple and efficient, and can be applied to any species. Here we present a case study by applying CountEm to a real ecological survey with 278 images of Greater Snow Geese (Anser caerulescens atlanticus) and Common Eiders (Somateria mollissima) flocks taken from fixed-wing aircraft in Eastern Canada. First, we evaluated the precision and counting time of CountEm on single images. Second, we developed and tested a new multi-image version of the CountEm software. We show that flock sizes of N?>?35,000 can be estimated on single images in ?5 min, from counting a sample of ?200 birds, yielding relative SEs in the 5%?10% range. Processing times increased to 10?20?min when simultaneously processing large numbers of images that contained over half a million birds with only modest increases in relative SE (range: 10%?15%). Our results suggest that CountEm may be used to save time and resources if incorporated into monitoring programs that utilize imagery in the abundance estimates.Proyecto Puente (Contrato Programa Gobierno de Cantabria-Universidad de Cantabria), Consejería de Universidades, Igualdad, Cultura y Deporte del Gobierno de Cantabri

Casimir scaling of domain wall tensions in the deconfined phase of D=3+1 SU(N) gauge theories

We perform lattice calculations of the spatial 't Hooft k-string tensions in the deconfined phase of SU(N) gauge theories for N=2,3,4,6. These equal (up to a factor of T) the surface tensions of the domain walls between the corresponding (Euclidean) deconfined phases. For T much larger than Tc our results match on to the known perturbative result, which exhibits Casimir Scaling, being proportional to k(N-k). At lower T the coupling becomes stronger and, not surprisingly, our calculations show large deviations from the perturbative T-dependence. Despite this we find that the behaviour proportional to k(N-k) persists very accurately down to temperatures very close to Tc. Thus the Casimir Scaling of the 't Hooft tension appears to be a `universal' feature that is more general than its appearance in the low order high-T perturbative calculation. We observe the `wetting' of these k-walls at T around Tc and the (almost inevitable) `perfect wetting' of the k=N/2 domain wall. Our calculations show that as T tends to Tc the magnitude of the spatial `t Hooft string tension decreases rapidly. This suggests the existence of a (would-be) 't Hooft string condensation transition at some temperature which is close to but below Tc. We speculate on the `dual' relationship between this and the (would-be) confining string condensation at the Hagedorn temperature that is close to but above Tc.Comment: 40 pages, 14 figure