Modélisation des disjoncteurs domestiques dans la bande CPL

Les études portant sur l'impact des éléments de protection du réseau électrique domestique sur les signaux CPL (courant porteur en ligne) manquent. Ce travail investigue l'effet des disjoncteurs domestiques dans la bande CPL. Avec un analyseur de réseau, les pertes d'insertion (paramètres S21) d'une dizaine de disjoncteurs de différents calibres et fabricants ont été mesurées. D'une part, l'atténuation des disjoncteurs dans la bande bas débit (9kHz-500 kHz) est faible. D'autre part, ils induisent une atténuation importante dans la bande haut débit (1MHz-100MHz). Ces pertes dépendent surtout du courant nominal et du type de disjoncteur (branchement, différentiel, divisionnaire). En tenant compte de leur structure, un circuit électrique équivalent des disjoncteurs est proposé et validé en comparant les simulations aux mesures. Ce circuit pourra être intégré dans un simulateur CPL

Variations in the predicted spatial distribution of atmospheric nitrogen deposition and their impact on carbon uptake by terrestrial ecosystems

Widespread mobilization of nitrogen into the atmosphere from industry, agriculture, and biomass burning and its subsequent deposition have the potential to alleviate nitrogen limitation of productivity in terrestrial ecosystems, and may contribute to enhanced terrestrial carbon uptake. To evaluate the importance of the spatial distribution of nitrogen deposition for carbon uptake and to better quantify its magnitude and uncertainty NOy-N deposition fields from five different three-dimensional chemical models, GCTM, GRANTOUR, IMAGES, MOGUNTIA, and ECHAM were used to drive NDEP, a perturbation model of terrestrial carbon uptake. Differences in atmospheric sources of NOx-N, transport, resolution, and representation of chemistry, contribute to the distinct spatial patterns of nitrogen deposition on the global land surface; these differences lead to distinct patterns of carbon uptake that vary between 0.7 and 1.3 Gt C yr−1 globally. Less than 10% of the nitrogen was deposited on forests which were most able to respond with increased carbon storage because of the wide C:N ratio of wood as well as its long lifetime. Addition of NHx-N to NOy-N deposition, increased global terrestrial carbon storage to between 1.5 and 2.0 Gt C yr−1, while the “missing terrestrial sink” is quite similar in magnitude. Thus global air pollution appears to be an important influence on the global carbon cycle. If N fertilization of the terrestrial biosphere accounts for the “missing” C sink or a substantial portion of it, we would expect significant reductions in its magnitude over the next century as terrestrial ecosystems become N saturated and O3 pollution expands

Reduction of the impulsive noise emitted by a resistive load commutation

International audienceIn power line or any cable communications, impulsive noise is assumed to be the most difficult noise to filter. In particular, it is impossible to predict when a non periodic asynchronous impulsive noise will appear. So, under such noise conditions, the OFDM symbol generally used in PLC, is corrupted. Signal-to-noise ratio is generally improved by detecting and/or filtering such noise to overcome this problem. Unfortunately, this leads to heavy detection and computing time in comparison with the disturbance duration. In this paper, we propose a new approach that consists in controlling the instant of commutation of a load. This approach allows reducing up to 15 dB the asynchronous impulsive noise emitted by a radiator in a 75-μs typical OFDM symbol duration

Sustainable Improvement and Use of the Protected Areasof West Africa: a New Challenge, Myth or Potential?

Over-accustomed by the media to the sight of the parks of East Africa where spectacular species like the famous “Big Five” rival for attention with great herds of animals, tourists are often disappointed by what the protected areas of West Africa have to offer them. The result is that the national parks of this part of the continent are little visited, in addition to the fact that their facilities are often in poor condition and they are rarely offered at competitive prices by the travel agen..

Valorisation et exploitation durable des aires protégées d'Afrique occidentale : un nouveau défi, mythe ou potentialité ?

Sur habitués par les médias au spectacle des parcs d'Afrique de l'Est où les espèces spectaculaires comme les fameux « Big Five » le disputent aux grandes concentrations d'animaux, les touristes sont souvent déçus par celui que leur proposent les aires protégées d'Afrique Occidentale. Il en résulte que les parcs nationaux de cette partie du continent sont peu visités et ce, d'autant plus que leurs infrastructures d'accueil sont souvent en mauvais état et qu'ils sont rarement proposés à des pr..

Résistivimétrie MT avec tests de stationnarité et de cohérence

Il est possible d'améliorer la mesure de la résistivité apparente du sol par la méthode magnétotellurique grâce à un tri préalable des données (partitionnées en blocs de segments) en cinq étapes : i) élimination des segments avec transitoires après filtrage passe-haut pour atténuer les composantes basse fréquence, ii) élimination des segments non stationnaires pour la variance par bandes de fréquence, iii) élimination des paires de segments non cohérentes, iv) dans chaque bande de fréquence, estimation des auto et inter-spectres par bloc, avec la méthode de Nuttall-Carter, v) élimination des paires de blocs non cohérentes. Basée sur les tests statistiques d'hypothèse, la méthode proposée permet d'apprécier l'amélioration de la qualité de la mesure en fonction du niveau commun des tests

A New Concept of Virtual Patient for Real-Time ECG Analyzers

International audienceDesigning real-time systems such as electrocardiogram (ECG) analyzers and evaluating their performance precisely is not an easy task. One of the difficulties is due to the general loss of performance that is frequently observed when implementing data processing algorithms on such systems and running the devices in new environments. Performance values are traditionally estimated theoretically or numerically (personal computer simulations) or are evaluated on real data but in a simulated environment. While the best performance measurements are accredited due to experiments driven in a real environment, the data at stake in this case are not entirely controlled. We propose in this paper the new concept of a virtual patient for real-time ECG analyzers. This concept enables a real environment to be created virtually by generating signals from a database composed of real acquired data. The analog signals generated will be seen by the analyzer as if they were coming from instantaneous electrical heart activities. This procedure provides a more correct assessment of the ECG analyzer performance than was previously possible. The test bench is useful for Holter manufacturers since it can deliver genuine performance values of the device

Reduction of the impulsive noise emitted by a resistive load commutation

International audienceIn power line or any cable communications, impulsive noise is assumed to be the most difficult noise to filter. In particular, it is impossible to predict when a non periodic asynchronous impulsive noise will appear. So, under such noise conditions, the OFDM symbol generally used in PLC, is corrupted. Signal-to-noise ratio is generally improved by detecting and/or filtering such noise to overcome this problem. Unfortunately, this leads to heavy detection and computing time in comparison with the disturbance duration. In this paper, we propose a new approach that consists in controlling the instant of commutation of a load. This approach allows reducing up to 15 dB the asynchronous impulsive noise emitted by a radiator in a 75-μs typical OFDM symbol duration