Multiplicative Noise Removal Using L1 Fidelity on Frame Coefficients

We address the denoising of images contaminated with multiplicative noise, e.g. speckle noise. Classical ways to solve such problems are filtering, statistical (Bayesian) methods, variational methods, and methods that convert the multiplicative noise into additive noise (using a logarithmic function), shrinkage of the coefficients of the log-image data in a wavelet basis or in a frame, and transform back the result using an exponential function. We propose a method composed of several stages: we use the log-image data and apply a reasonable under-optimal hard-thresholding on its curvelet transform; then we apply a variational method where we minimize a specialized criterion composed of an $\ell^1$ data-fitting to the thresholded coefficients and a Total Variation regularization (TV) term in the image domain; the restored image is an exponential of the obtained minimizer, weighted in a way that the mean of the original image is preserved. Our restored images combine the advantages of shrinkage and variational methods and avoid their main drawbacks. For the minimization stage, we propose a properly adapted fast minimization scheme based on Douglas-Rachford splitting. The existence of a minimizer of our specialized criterion being proven, we demonstrate the convergence of the minimization scheme. The obtained numerical results outperform the main alternative methods

JUMPING PERFORMANCES IN NATIONAL 2 WOMEN HANDBALL PLAYERS: EFFECT OF A 3-MONTH PLYOMETRIC TRAINING PROGRAM

This study investigates both jumping performances (in squat jump (SJ) and counter movement jump (CMJ)) and global lower limbs stiffness in women handball players and reports the effect of a 3-month plyometric training program (length: 45 min, once a week) on these parameters. Mean performance for SJ was 22.3±3.0 cm and for CMJ 29.3±4.1 cm. Lower limbs stiffness reached 21213±7510 N.m-1. There was no correlation between the different parameters. Eight players followed the plyometric program but six were finally evaluated because of injuries. No change was observed for CMJ but lower limbs stiffness and SJ height tend to increase. This suggests that a unique 45-min plyometric training session once a week during three months may not be enough to enhance jumping capacities and lower limbs stiffness in women handball players

Simulating the long term impact of nitrate mitigation scenarios in apilot study basin

The agro-hydrological model TNT2 was used to explore for a period of 14 years (1987–2001) the likelyconsequences of mitigation scenarios on nitrate contamination of the stream water in a small agriculturalcatchment. The Best Management Practices (BMPs) historically designed and implemented in 1992 andtwo devised agricultural scenarios (catch crop (CC) implementation and a global reduction of N fertilizer)are evaluated in term of nitrate contamination in the environment. Two of the BMPs consist in imple-menting natural strips of Poplar and rye-grass strips (5 meters large) along stream and ditches and thethird is a delay in the burial of wheat straws (from August to October). Simulations indicated that naturalstrips implementation would lead to a slight decrease of Nitrate Fluxes (NF) in river by respectively 3.3%and 6.6% for rye-grass and poplar strips: a benefit associated to the non fertilization of strips area. Denitri-fication has not been particularly disrupted in such areas. The delay in the burial of wheat straw in autumndecreases annual mineralization rate and annual plant uptake (by respectively 9 and 13 kg N ha−1y−1)but increases denitrification fluxes by 6 kg N ha−1y−1. This would lead to a slight decrease by 6% of NFin stream (equivalent to 3.3 mg NO3−l−1) and an average decrease of the following sunflower yield by27%. The global reduction of fertilization by 10% would decreased NF in stream by 13.8% (equivalent to8 mg NO3−l−1), with a global decrease by 8 kg N ha−1y−1of plant uptake. The cumulative effect of BMPsand CC would have together lead to a decrease of nitrate concentration from 57.5 to 46.6 mg NO3−l−1reaching the UE environmental quality objectives (below 50 mg NO3−l−1). Spring crops yield followingCC would have been penalized and the decrease of NF is balanced by an increase of denitrification fluxesin the environment contributing to release of N2O, a greenhouse gas, into the atmosphere

Interphonologie et représentations orthographiques. Le cas des catégories /b/ et /v/ chez des apprenants japonais de Français Langue Etrangère.

L'article essaie de clarifier l'apprentissage de catégories phonologiques dans une langue seconde quand cette dernière ne fait pas partie des catégories de la langue source. Il soulève aussi la question de l'orthographe et la façon dont elle peut interagir dans l'apprentissage pour des langues à longue tradition orthographique comme le japonais ou le français

Event-Triggered Observer-based Output-Feedback Stabilization of Linear System with Communication Delays in the Measurements

International audienceIn this paper, an original framework is proposed for the stabilization of a linear system with delays in the measurements: i) an observer estimates the full state information of the plant from a partial measurement, ii) an event-based control technique computes and updates the control signal only when a certain condition is satisfied and iii) an event-based corrector updates the model used to calculate the control law when it deviates from the estimated state. It is notably proved that such a proposal renders the closed-loop system stable for larger delays in the measurements than in the classical continuous-time control case. Simulation results are provided

Event-based Stabilization of Nonlinear Time-Delay Systems

International audienceIn this paper, a universal formula is proposed for event-based stabilization of nonlinear time-delay systems affine in the control. The feedback is derived from the original one proposed by E. Sontag (1989) and previously extended to event-based control of nonlinear undelayed systems. Under the assumption of the existence of a control Lyapunov-Krasovsky functional, it enables smooth (except at the origin) asymptotic stabilization while ensuring that the sampling intervals do not contract to zero. Global asymptotic stability is obtain under the small control property assumption. Moreover, the control can be proved to be smooth anywhere under certain conditions. Some simulation results highlight the ability of the proposals

Dynamics of Nitrogen loads in surface water of an agricultural watershed by modelling approach, the Save, Southwest France.

Agriculture is known to have a great impact of nutrients enrichment on continental water resources. In south-West of France (Gascogne region), water resource are essentially surface water and shallow aquifer. Nitrogen dynamic in river is complex and highly variable throughout season and year, depending on hydrology, landuse, removal in stream. In this context, agricultural impacts on nitrogen concentration are a matter of concern for agricultural decision-maker. In order to introduce sustainable land use concepts in this hilly, clayey and agricultural shallow soil context, the hydrological simulation model SWAT2005 has been tested as a valuable tool to evaluate the consequences of such land use changes on water and nutrient balance components. This semi-distributed hydrological model coupled with agronomical model EPIC is able to simulate the impact of each agricultural landuse at the outlet of the Save catchment (1100 km2). Hydrological parameters model are calibrated based on 14-year historical record (1994–2008). Nitrogen losses have been measured during 2 years (2006-2008) at the outlet and are used to validate the model calibration. Agricultural data at communal scale coupled with Spot image analyses have been used to evaluate agricultural distribution and pressure in SWAT. The aim of this modelling exercise is to simulate nitrogen cycle in whole agricultural Hydrological Response Units (HRU), depending on plant growth and culture rotation, to simulate accurately nitrate load in river. The ability of SWAT to reproduce nitrogen transfert and transformation at this scale and in this agricultural context will be evaluated by a discussion of importance of each nitrogen cycle process in nitrogen losses. SWAT could be a useful tool to test agricultural scenario to improve the nitrogen management in river

Long term nitrogen budget modelling in a small agricultural watershed: hydrological control assessment of nitrogen losses with semi-distributed (SWAT) and distributed (TNT2) models

Nitrogen exports in catchments are known to be greatly variable because nitrogen cycle in watershed is controlled by different factors such as landuse, farm management practices, climate, soil type and hydrological setting. Our aim is to study the relative importance of the processes controlling nitrogen losses at catchment scale in the long term using a modelling approach constrained by a long term record of observations. The study area is a catchment of 330 ha with 95 % of intensive agriculture in a hilly shallow soil context, in the south west of France. Historical field rotation and nitrogen river load data have been collected for a 20 year period. Two process-based and spatially distributed models have been chosen to simulate nitrogen transfer and transformation in the whole catchment. The first one is the fully distributed TNT2 model, developed and validated in a different context (farming systems in north-western France). The second one is the widely used, semi-distributed SWAT model, used and recognizedto be realistic in many studies on nitrogen transfer in river. This comparative modelling approach was used to evaluate the effect of different modelling approaches on the identification of controlling factors, and the ability of both models to simulate alternative scenarios. The discharge, especially during storm flow, is well simulated by the curve number approach and the semi-distributed hydrological parameter description used SWAT, while the Topmodel-derived approach used in TNT2 tends to underestimate some peak discharges. Nitrogen dynamic simulations are considered to be acceptable for both models for a long time period but the use of both models allows to exhibit their respective capacity and limits. TNT2 has higher potentiality to test the impact of complex agricultural scenarios because the description of management practices and the simulation of crops to management options is more detailed. It permits the assessment of spatial interactions and focussed spatial management, like the set up of grass or tree strips. SWAT can then be used to scale up change scenarios from TNT2 small catchment results to large catchments

Les outils pour acquérir et transformer la matière ligneuse dans les chaînes opératoires techniques des artisanats forestiers en Provence et Haut-Dauphiné au Moyen Âge

International audienceThe interweaving of historical (charters and notarial sources, literary sources, iconography), archaeological and ethnoarchaeological data focuses on three major questions : how are tools made partially from wood made to work this same material, how can they be identified and recognized in technical processes, and what are the technical gestures used . The results underline the great variability in the way of using the same Tools in different stages of different technical processes. Technical innovation and intensive change in craft production during the late Middle Ages is also discussed.Le croisement des données historiques (actes de la ratique, littérature savante, iconographie), archéologiques et thnoarchéologiques s'organise autour de trois questions principales : celle de la fabrication même des outils qui sont façonnés pro parte dans la matière qu'ils ont vocation à travailler, le bois ; celle de l'identification des outils et de leur mise en oeuvre dans les chaînes opératoires techniques liées à l'acquisition et à la transformation de la matière ligneuse et enfin celle des gestes techniques. Les résultats soulignent une grande polyvalence des outils qui interviennent à des stades précis d'opérations de chaînes différentes. La question de l'innovation technique et de l'" industrialisation " au Bas Moyen Âge est abordée

French in Auvergne (Centre) : a speaker from Clermont-Ferrand

International audienceCette enquête PFC (phonologie du français contemporain) a été faite avec une locutrice junior de la région proche de clermont-Ferrand. l'ensemble des données nous amènent à conclure que ses productions ne sont pas très éloignées du français de référence. on retiendra en revanche des élément typiques du français jeune