Volumetric measurements by tomographic PIV of grid generated turbulence in an open channel flow

International audienceThis paper investigates the energy dissipation rate behind two combinations of trash racks (or meshes) in an open channel flow. Five trash rack assemblies divided the flume into four identical pools in the downstream direction. The global characteristics of the flow were compared with Tomo-PIV measurements that were taken in the water column of the flow. From the Tomo-PIV measurements, the instantaneous structures in the flow were visualised and the decay of turbulent kinetic energy and energy dissipation analysed

Volumetric Measurements by Tomographic PIV of an Open Channel Flow Behind a Turbulent Grid

National audienceThis paper investigates the energy dissipation rate behind two combinations of trash racks (or meshes) in an open channel flow from tomo-PIV measurements. Five trash rack assemblies divided the flume into four identical pools. Each trash rack assembly is composed of a fine wire mesh and two regular square grids, characterised by their mesh size M. The Reynolds numbers with respect to M were 4300 and 9600 corresponding to a mean velocity ¯U through each pool between 0.35 and 0.315 m/s. This aim of this paper is to investigate the turbulent energy dissipation behind two configurations of regular grids in an open channel

Mesure volumique par tomo-PIV d'un écoulement dans un canal turbulent de surface libre derrière une grille

National audienceLa mesure directe de la dissipation dans les écoulements n'est pas possible mais les nouvelles techniques de mesure volumique comme la tomo-PIV permettre de calculer le tenseur des gradients de vitesse et par la même la dissipation instantanée. Cet article présente des mesures de vitesse par tomo-PIV d'un écoulement à surface libre pour un nombre de Reynolds de 36000 dans un canal incliné à l'aval d'un assemblage de grilles. La faisabilité des mesures est réalisée et deux configurations de grilles sont comparées. On montre notamment que la dissipation n'est pas homogène et isotrope dans la région de l'écoulement mesurée

Implementation of vibration correction schemes to the evaluation of a turbulent flow in an open channel by tomographic particle image velocimetry

International audienceThe aim of this paper is to investigate and quantify the effect of vibration on experimental tomographic particle image velocimetry (TPIV) measurements. The experiment consisted of turbulence measurements in an open channel flow. Specifically, five trash rack assemblies, composed of regular grids, divided a 5 m long flume into four sequential, identical pools. This set-up established a globally stationary flow, with each pool generating a controlled amount of turbulence that is reset at every trash rack. TPIV measurements were taken in the central pool. To eliminate the vibration from the measurements, three vibration correction regimes are proposed and compared to a global volume self-calibration (Wieneke 2008 Exp. Fluids 45 549–56), a now standard calibration procedure in TPIV. As the amplitude of the vibrations was small, it was possible to extract acceptable reconstruction re-projection qualities ( Q I > 75%) and velocity fields from the standard treatment. This paper investigates the effect of vibration on the cross-correlation signal and turbulence statistics, and shows the improvement to velocity field data by several correction schemes. A synthetic model was tested that simulated camera vibration to demonstrate its effects on key velocity parameters and to observe the effects on reconstruction and cross-correlation metrics. This work has implications for experimental measurements where vibrations are unavoidable and seemingly undetectable such as those in large open channel flows

Clinical glove use improvement: an observational and microbiological study identifying educational priorities

National audienc

Sélection du palmier à huile pour une huile de palme durable et responsabilité sociale

As an actor of a supply chain, seed producers must take into account the impact of their work on sustainability. This is particularly true when one works on palm oil, a highly sensitive crop which is questioned on its social and environmental impact. Breeders act directly on yield thus increasing profitability, while for the same production, decreasing land-use pressure. In addition, breeders act on duration of the plantations - which is critical for a perennial crop - making strategic choices selecting for lasting resistances to diseases. They can seek rustic selections, which help the work of small holders and enable them to a better social insertion in the supply chain. In the long trend, the promotion of sustainable palm oil is an excellent opportunity for palm oil seed distributors. Corporate and Social Responsibility of PalmElit, company recently created, is presented. It defines its aspirations, its values, its direct and indirect responsibilities and finally proposes an operational code of conduct. (Résumé d'auteur

Sélection du palmier à huile pour une huile de palme durable et responsabilité sociale

As an actor of a supply chain, seed producers must take into account the impact of their work on sustainability. This is particularly true when one works on palm oil, a highly sensitive crop which is questioned on its social and environmental impact. Breeders act directly on yield thus increasing profitability, while for the same production, decreasing land-use pressure. In addition, breeders act on duration of the plantations - which is critical for a perennial crop - making strategic choices selecting for lasting resistances to diseases. They can seek rustic selections, which help the work of small holders and enable them to a better social insertion in the supply chain. In the long trend, the promotion of sustainable palm oil is an excellent opportunity for palm oil seed distributors. Corporate and Social Responsibility of PalmElit, company recently created, is presented. It defines its aspirations, its values, its direct and indirect responsibilities and finally proposes an operational code of conduct

Improving the accuracy of genomic predictions in an outcrossing species with hybrid cultivars between heterozygote parents: a case study of oil palm (Elaeis guineensis Jacq.)

International audienceGenomic selection (GS) is a method of marker-assisted selection revolutionizing crop improvement, but it can still be optimized. For hybrid breeding between heterozygote parents of different populations or species, specific aspects can be considered to increase GS accuracy: (1) training population genotyping, i.e., only genotyping the hybrid parents or also a sample of hybrid individuals, and (2) marker effects modeling, i.e., using population-specific effects of single nucleotide polymorphism alleles model (PSAM) or across-population SNP genotype model (ASGM). Here, this was investigated empirically for the prediction of the performances of oil palm hybrids for yield traits. The GS model was trained on 352 hybrid crosses and validated on 213 independent hybrid crosses. The training and validation hybrid parents and 399 training hybrid individuals were genotyping by sequencing. Despite the small proportion of hybrid individuals genotyped and low parental heterozygosity, GS prediction accuracy increased on average by 5% (range 1.4-31.3%, depending on trait and model) when training was done using genomic data on hybrids and parents compared with only parental genomic data. With ASGM, GS prediction accuracy increased on average by 3% (- 10.2 to 40%, depending on trait and genotyping strategy) compared with PSAM. We conclude that the best GS strategy for oil palm is to aggregate genomic data of parents and hybrid individuals and to ignore the parental origin of marker alleles (ASGM). To gain a better insight into these results, future studies should examine the respective effect of capturing genetic variability within crosses and taking segregation distortion into account when genotyping hybrid individuals, and investigate the factors controlling the relative performances of ASGM and PSAM in hybrid crops

Oil palm (Elaeis guineensis Jacq.) genetic differences in mineral nutrition : specific leaflet mineral concentrations of high-yielding oil palm progenies and their implications for managing K and Mg nutrition

Background and aims In oil palm, similar fertilization treatments can result in leaflet potassium and magnesium concentrations that vary significantly from one progeny to another. This hinders the development of standardized fertilizer recommendations for this crop, as they are usually calculated based on optimum leaflet nutrient concentrations. Methods Four high-yielding oil palm progenies with contrasting leaflet K and Mg concentrations (C1, C2, and C3 of Deli x La Me origin and C4 of Deli x Yangambi origin) were treated with combinations of three levels of KCl and MgSO4, in a completely randomized split-plot factorial design with six replicates, where progenies were a sub-factor. Results For a given level of KCl or MgSO4, different leaflet K and Mg concentrations were found between progenies (p < 0.0001). Leaflet K concentration and yield response to KCl applications revealed that the four oil palm progenies have different optimum leaflet K concentrations. In our study period (5-8 YAP), progenies C1 and C3 showed their highest fresh fruit bunch (FFB) yields (13.62 and 16.54 t ha(-1) year(-1), respectively) at K2, whereas progenies C2 and C4 showed their highest yields (14.62 and 12.39 t ha(-1) year(-1), respectively) at K1. Conclusion Our study highlighted specific optimum leaflet K and Mg concentrations for different oil palm progenies in a given environment. It paves the way for adopting K and Mg fertilizer application rates adapted to specific requirements of each type of oil palm planting material