Robustness of nuclear core activity reconstruction by data assimilation

We apply a data assimilation techniques, inspired from meteorological applications, to perform an optimal reconstruction of the neutronic activity field in a nuclear core. Both measurements, and information coming from a numerical model, are used. We first study the robustness of the method when the amount of measured information decreases. We then study the influence of the nature of the instruments and their spatial repartition on the efficiency of the field reconstruction

Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

Using data assimilation framework, to merge information from model and measurement, an optimal reconstruction of the neutronic activity field can be determined for a nuclear reactor core. In this paper, we focus on solving the inverse problem of determining an optimal repartition of the measuring instruments within the core, to get the best possible results from the data assimilation reconstruction procedure. The position optimisation is realised using Simulated Annealing algorithm, based on the Metropolis-Hastings one. Moreover, in order to address the optimisation computing challenge, algebraic improvements of data assimilation have been developed and are presented here.Comment: 24 pages, 10 figure

Singular linear systems on Lie groups; equivalence

International audienc

Animal traction in developed countries: The reappropriation of a past practice through agroecological transition

International audienceAs part of the current agroecological transition, animal traction in agriculture is benefiting from an increased focus in developed countries. However, the practice is struggling to gain recognition from research, institutions and the agricultural profession. This article aims to analyze how animal traction is treated in developed countries, and to assess the extent to which it could be considered an agroecological practice. We analyze animal traction as a scientific object and a socio-professional movement. Our methodology is based on a review of scientific literature and an analysis of the French general press. The various studies show that animal traction has advantages in terms of energy, economics and agronomy. It tends to be developed by alternative movements and farmers motivated by a desire to redesign our food systems. Both scientific and press reviews show a renewed positive interest in animal traction. Although these reviews highlight its agroecological potential, the practice is facing difficulties in gaining recognition. The findings of this article are of obvious interest to rural development researchers and policy makers. They help the former to explore new issues in the return of animal traction, and the latter to better understand the development factors of this practice

État des lieux des flux céréaliers en Wallonie selon différentes filières d’utilisation

Survey on cereal resources in Wallonia according to their different uses. Survey on cereal resources in Wallonia according to their different uses. More than 60% of the arable cropped area in Wallonia is dedicated to cereals. Cereal chains were initially aimed at ensuring food security but are now progressively oriented towards new non-food uses. Walloon cereal chains are now having to face up to new global challenges: to ensure the competitiveness and sustainability of vegetal and animal chains, to match society's expectations and to meet the biomass needs for energy uses and bio-based products. Within this framework, this research aims to evaluate the environmental and socio-economic sustainability of future scenarios of current and potential food and non-food uses for Walloon cereals. This paper, the first in a series of two, presents the current picture of Walloon cereal crops and their uses. Various steps are analyzed: production, collection, wholesale and processing. Four main uses characterize cereal processing: the so-called "4Fs", representing Food (human food uses), Feed (animal feed uses), Fuel (energy uses) and Fiber (material uses). Data collected from stakeholders in the Walloon cereal chain enabled us to assess cereal flows for the "4Fs", drawing a qualitative and a quantitative picture of Walloon cereal resources including the key elements of the cereal chains. This approach serves as a basis for a prospective exercise, described in a companion paper, which develops potential uses for Walloon cereal resources at the 2030 horizon.Alt-4-Ce

On the accuracy of genomic selection

Genomic selection is focused on prediction of breeding values of selection candidates by means of high density of markers. It relies on the assumption that all quantitative trait loci (QTLs) tend to be in strong linkage disequilibrium (LD) with at least one marker. In this context, we present theoretical results regarding the accuracy of genomic selection, i.e., the correlation between predicted and true breeding values. Typically, for individuals (so-called test individuals), breeding values are predicted by means of markers, using marker effects estimated by fitting a ridge regression model to a set of training individuals. We present a theoretical expression for the accuracy; this expression is suitable for any configurations of LD between QTLs and markers. We also introduce a new accuracy proxy that is free of the QTL parameters and easily computable; it outperforms the proxies suggested in the literature, in particular, those based on an estimated effective number of independent loci (Me). The theoretical formula, the new proxy, and existing proxies were compared for simulated data, and the results point to the validity of our approach. The calculations were also illustrated on a new perennial ryegrass set (367 individuals) genotyped for 24,957 single nucleotide polymorphisms (SNPs). In this case, most of the proxies studied yielded similar results because of the lack of markers for coverage of the entire genome (2.7 Gb)

A multi-faceted pandemic: a review of the state of knowledge on the Zika virus

Abstract While until recently the small and isolated Zika outbreaks in Eastern Asia and Pacific islands had been overlooked, the large-scale outbreak that started in Brazil in 2015 and the increase of microcephaly cases in the same place and time made media headlines. Considered as harmless until recently, Zika has given rise to an important global crisis that poses not only health challenges but also environmental, economical, social, and ethical challenges for states and people around the world. The main objective of this paper is to review the recent Zika outbreak by covering a broad range of disciplines and their interactions. This paper synthetises experts’ interviews and reactions conducted during a Massive Open Online Course (MOOC) entitled “In the footsteps of Zika…approaching the unknown.” It reviews knowledge and uncertainties around epidemiology, geographical dispersion of the virus and its vectors through globalization and climate change, and also its modes of transmission, diagnosis, symptoms, and treatment of the disease. The resulting societal and ethical issues in pregnancy and women of reproductive age were also addressed as well as the global outbreak alert and response network in international organizations and social media. This paper attempted to combine each piece of the jigsaw puzzle of the Zika phenomenon to complete the best realistic picture, while keeping in mind the balance between the interdisciplinary nature and international context of Zika and its unique characteristics

Global 4DVAR Assimilation and Forecast Experiments Using AMSU Observations over Land. Part II: Impacts of Assimilating Surface-Sensitive Channels on the African Monsoon during AMMA

International audienceObservations from Advanced Microwave Sounding Unit-A and -B (AMSU-A and -B) have been more intensively used over sea than over land because of large uncertainties about the land surface emissivity and the skin temperature. Several methods based on a direct estimation of the land emissivity from satellite observations have been found to be very useful for improving the assimilation of sounding channels over land. Feasibility studies have been conducted within the Météo-France global assimilation system in order to examine the possibility of assimilating low-level atmospheric observations receiving a contribution from the land surface. The present study reports on three 2-month assimilation and forecast experiments, which include the assimilation of surface-sensitive observations from AMSU-A and -B together with a control experiment, which represents the operational model. The assimilation experiments have been compared with the control, and important changes in the analyzed atmospheric fields and in the precipitation forecasts over parts of the tropics, and especially over West Africa, have been noticed. The experiments seem to emphasize the atmospheric moistening in India, South America, and in West Africa, together with atmospheric drying over Saudi Arabia and northeast Africa. The drying or moistening of the atmosphere has been successfully evaluated using independent measurements from the GPS African Monsoon Multidisciplinary Analysis (AMMA) network. Precipitation and OLR forecasts have also been examined and compared with independent measurements. Physically, the changes result in a better-organized African monsoon with a stronger ITCZ in terms of ascent, vorticity, and precipitation, but there is no northward shift of the monsoon system. Low-level humidity observations have been found to have important impacts on the analysis and to produce positive impacts on forecast scores over the tropics