Application of multireflection grazing incidence method for stress measurements in polished Al–Mg alloy and CrN coating

Multi-reflection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of Al–Mg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The influence of different mechanical treatments on residual stresses was studied for Al–Mg samples. It was found that both rolling and mechanical polishing influence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined

Application of multireflection grazing incidence method for stress measurements in polished Al–Mg alloy and CrN coating

Multi-reflection grazing incidence geometry, referred to as MGIXD, characterized by a small and constant incidence angle, was applied to measure low surface stresses in very thin layers of Al–Mg alloy and CrN coating. These two materials were selected in order to deal with the low and high levels of residual stress, respectively. The influence of different mechanical treatments on residual stresses was studied for Al–Mg samples. It was found that both rolling and mechanical polishing influence the distribution and amplitude of residual stress in surface layers. In the case of CrN coating, a very high compressive stress was generated during the deposition process. The stress distributions determined by the MGIXD method is in good agreement with the classic sin2 technique results for all studied samples. In performing stress measurements for a powder sample, it was found that the application of the Göbel mirror in the incident beam strongly reduces statistical and misalignment errors. Additionally, the root mean square values of the third order lattice strain within diffracting grains were determined

COMPETITION AND FACILITATION EFFECTS OF DIFFERENTIAL INTRA-AND INTER-ROW WEED MANAGEMENT IN SUGARCANE

International audienceDifferential intra-and inter-row weed management can be a mean to reduce herbicide use in sugarcane. In 2011, a field experiment was conducted in La Reunion Island to assess inter-row weed competition. Four inter-row weed competition treatments for a duration of one (T1), two (T2), three (T3) and four (T4) months after planting were compared in a randomized complete block design with 5 replicates; treatment plots were paired with non-weeded inter-row control plots. All intra-rows where kept weed-free all season long. Weeds covered 100% of the inter-rows by three months after planting. Sugarcane grew far above the weed canopy, completely closing the canopy between the rows for all treatments. Sugarcane yield decreased by 13 t/ha/month of early weed competition. However, the control yield, expected to be lower than T4, was similar to the T3 treatment. This suggests a late facilitation effect of the inter-rows vegetation in control plots which partially compensates for its early competition effect. This may be due to the particular flora of our experiment, with high populations of N-fixing weeds and broom weeds. The root length density profiles observed in a couple of plots may support the facilitation hypothesis. However, additional research is needed to corroborate this singular result.Une gestion rang inter-rang différenciée pourrait générer des économies d'herbicides en culture de canne à sucre. En 2011 à La Réunion, dans un essai de nuisibilité sur canne vierge à rangs maintenus propres, les adventices des inter-rangs ont amputé le rendement en canne à sucre de 10% par mois de concurrence précoce pendant les quatre premiers mois du cycle. Le rendement des témoins à inter-rangs non désherbés a été significativement supérieur au traitement ayant subi quatre mois de concurrence. Une compensation partielle et tardive de la concurrence précoce est donc intervenue, ce qui suggère des phénomènes de facilitation de la part des adventices confinées dans les inter-rangs sous la canne jusqu'en fin de cycle. La flore atypique de l'essai dominée par des fixatrices d'azote et des malvacées connues pour la puissance de leur enracinement pivotant pourrait être en cause ; les profils de densités de longueur racinaire réalisés sur un couple de parcelles ne sont pas incohérents avec cette hypothèse qui reste à vérifier