Etude comparative d'aciers pour coquilles de coulée basse pression d'aluminium

37èmes journées du cercle d'études des métaux, 27-28 mai 1998, Albi, FRANCEInternational audienc

Etude des potentialités des systèmes d'application contrôlée des gouttes (CDA) pour les traitements phytosanitaires en céréaliculture (synthèse bibliographique)

Study of the potential for the use of controlled droplet application (CDA) upon cereal crops. A review. Introduction. Controlled droplet application (CDA) has the advantage both of the reduction in the span of droplet size distribution and in the volume of liquid applied, in comparison with conventional hydraulic nozzles. Literature. This review investigates the potential for the use of CDA relative to hydraulic nozzles within the early stages of weed control (2-3 leaves). The studies reviewed examine spray retention, linking the droplet characteristics (size, velocity and direction) of spray liquids with the architecture, density and wettability of the foliage. These studies show that the use of droplets of 300 µm, combined with an appropriate adjuvant and applied with a 60° forward-angled spray, led to the enhanced depositing of liquids on upright surfaces. Assessment of the reduced volumes applied by both application techniques was based on the mean, the variation coefficient and the deposition coverage. However, these results cannot be generalized, due to the different operative settings in which the spray application techniques were employed. Regarding the risk of drift to the side, the drift potential of droplets generated horizontally by CDA nozzles is greater than that of the conventional technique with a downward orientation of spray. The drift potential increases as the wind velocity increases and the volume median diameter (DV50) decreases. Conclusions. New settings of CDA nozzles in terms of DV50 and the direction of spray may address the challenge of precision agriculture. Innovative ways to apply pesticides, based on CDA, must be explored in order to avoid the sensitivity to wear of the teeth in spray applicators and to obtain a narrower droplet-size distribution

Modelling Local Seismograms of French Nuclear Tests In Taourirt Tan Afella Massif, Hoggar, Algeria

Geophysical Journal International, vol. 199, n°3, pp. 964 - 974, 1994International audienc

Centroid Localization of Uncooperative Nodes in Wireless Networks Using a Relative Span Weighting Method

Increasingly ubiquitous wireless technologies require novel localization techniques to pinpoint the position of an uncooperative node, whether the target is a malicious device engaging in a security exploit or a low-battery handset in the middle of a critical emergency. Such scenarios necessitate that a radio signal source be localized by other network nodes efficiently, using minimal information. We propose two new algorithms for estimating the position of an uncooperative transmitter, based on the received signal strength (RSS) of a single target message at a set of receivers whose coordinates are known. As an extension to the concept of centroid localization, our mechanisms weigh each receiver's coordinates based on the message's relative RSS at that receiver, with respect to the span of RSS values over all receivers. The weights may decrease from the highest RSS receiver either linearly or exponentially. Our simulation results demonstrate that for all but the most sparsely populated wireless networks, our exponentially weighted mechanism localizes a target node within the regulations stipulated for emergency services location accuracy