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Although the leaf economic spectrum has deepened our understanding of leaf trait variability, little is known about how leaf traits scale with leaf area. This uncertainty has resulted in the assumption that leaf traits should vary by keeping the same pace of variation with increases in leaf area across the leaf size range. We evaluated the scaling of morphological, tissue-surface and vascular traits with overall leaf area, and the functional significance of such scaling. We examined 1,271 leaves for morphological traits, and 124 leaves for anatomical and hydraulic traits, from 38 trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a Neotropical genus of pioneer trees that can exhibit large laminas (0.4 m2 for C. obtusa), with leaf size ranging by two orders of magnitude. We measured (i) tissue fractions within petioles and their second moment of area, (ii) theoretical xylem hydraulic efficiency of petioles and (iii) the extent of leaf vessel widening within the hydraulic path. We found that different scaling of morphological trait variability allows for optimisation of lamina display among larger leaves, especially the positive allometric relationship between lamina area and petiole cross-sectional area. Increasing the fraction of pith is a key factor that increases the geometrical effect of supportive tissues on mechanical rigidity and thereby increases carbon-use efficiency. We found that increasing xylem hydraulic efficiency with vessel size results in lower leaf lamina area: xylem ratios, which also results in potential carbon savings for large leaves. We found that the vessel widening is consistent with hydraulic optimisation models. Leaf size variability modifies scaling of leaf traits in this large-leaved species.

Rheological parameters being of great importance for sludge process management, they are increasingly studied. However, experimental procedures may strongly impact their determination. Sample volume, measuring device depth and roughness but also mechanical history, have to be well-controlled to ensure reproducible results. Indeed, even if shear history can be erased with a sufficient preshear for diluted sludge, this paper clearly established that no steady state can be achieved for concentrated sludge. The longer the shear history, the lower the rheological characteristics: Reproducible results are hardly obtained. More importantly, slippage appeared to occur even with surfaces of moderate roughness and the phenomenon is all the more important that the dry matter is high. From all these observations, an experimental procedure based on the control of preshear and rest periods has been defined. Advices and precautions to observe are given in order to ensure reproducible and obtain unaltered results.

International audience; Despite recent publications, the strain transfer in distributed optical fiber sensors is still often overlooked and poorly understood. In the first part of this paper, strain transfer is shown to be driven by a second-order differential equation, whether the optical fiber is embedded into the host material or surface-mounted. In this governing equation, only the value of a key parameter, called strain lag parameter, varies according to the attachment configuration and the type of optical fiber used as a sensor. Then, a general solution of the governing equation is proposed. It is an analytical expression established from new boundary conditions that are more adequate than those used previously in the literature and allows the determination of the strain profile in the core of a distributed optical fiber sensor under any arbitrary strain fields. This general solution has been validated by two experiments presented in the third part of the paper. A very good agreement between the analytical solutions and measured strain profiles using a high spatial resolution optical interrogator for both uniform and non-uniform strain fields has been obtained. These results highlight the importance of the strain lag parameter which must be taken into account for a correct interpretation of measurements, especially in the case of important strain gradients.

International audience; In response to the demand from a growing number of people concerned about the possible impact of RF-EMF on health, the French National Frequency Agency (ANFR) has published a standardized protocol for in-situ measurements of radiofrequency electromagnetic fields (RF-EMF). This protocol was based on the search for the point of highest field strength and the use of spot measurement. In the framework of an epidemiological study, such spot measurements were implemented in the homes of 354 participants located in urban areas within 250 m of a mobile-phone base station (MPBS) and in the main beam direction of the antenna. Among the participants, more than half accepted to be enrolled in a longer-term study, among whom 152 were equipped with a personal exposure meter (PEM) for 48 h and 40 for seven continuous days. Both spot and PEM measurements quantified downlink field strengths, i.e. FM, TV3-4-5, TETRA I-II-III, 2 GHz-5GHz Wi-Fi, WiMax, GSM900, GSM1800, UMTS900, UMTS 2100, LTE800, LTE1800, and LTE2600. Spot measurements showed a mean/median field strength of 0.58/0.44 V/m for total RF-EMF and 0.43/0.27 V/m from the MPBS. RF-EMF from the MPBS was the dominant source of exposure in 64% of households. Exposure to RF-EMF was influenced by the position of the windows with respect to the MPBS, in particular line-of-site visibility, the distance of the antenna and the floor of the apartment. The PEM surveys showed the measured exposure to be higher during outings than at home and during the day than at night, but there was no difference between the weekends and working days. There was a strong correlation between exposure quantified by both spot and PEM measurements, although spot measures were approximately three times higher than those by PEMs. This study is the first to assess exposure to RF-EMF of people living near a MPBS in urban areas in France. These preliminary results suggest the value of using spot measurements to estimate the impact of the evolution of the mobile-phone network and technology on the exposure of populations to RF-EMF. The low levels of RF-RMF expressed as mean values do not necessarily rule out possible health effects of this exposure.

International audience; Combined with multivariate calibration methods, near-infrared (NIR) spectroscopy is a non-destructive, rapid, precise and inexpensive analytical method to predict chemical contents of organic products. Nevertheless, one practical limitation of this approach is that performance of the calibration model may decrease when the data are acquired with different spectrometers. To overcome this limitation, standardization methods exist, such as the piecewise direct standardization (PDS) algorithm.The dataset presented in this article consists of 332 manure samples from poultry and cattle, sampled from farms located in major regions of livestock production in mainland France and Reunion Island. The samples were analysed for seven chemical properties following conventional laboratory methods. NIR spectra were acquired with three spectrometers from fresh homogenized and dried ground samples and then standardized using the PDS algorithm. This important dataset can be used to train and test chemometric models and is of particular interest to NIR spectroscopists and agronomists who assess the agronomic value of animal waste. (C) 2020 The Authors. Published by Elsevier Inc.

Les instruments de mesure sont devenus des outils centraux dans le gouvernement de l’Afrique contemporaine. Suivant la focalisation sur la performance économique comme outil de réforme de l’aide au développement et des États, la mesure génère de nouvelles modalités d’intervention (expérimentation, quantification) et des reconfigurations politiques. Ces outils, instruments qui mobilisent des experts et savoirs spécifiques, mettent les États dans une position ambiguë, à la fois contraints par ces infrastructures techniques de l’action politique et disposant de marge de manœuvre pour s’affirmer sur leur population. Ils créent les conditions d’une infiltration, où les bailleurs internationaux, plutôt que d’imposer des conditions et mener des interventions externes, s’immiscent au sein des États africains au travers de techniques, mesures de standardisation, d’évaluation et une terminologie spécifique. Instruments of measures are more and more central in the government of contemporary Africa. They have become central in the rise of economic performance as a tool for reforming development aid and states. New ways of intervening and of producing public action in Africa emerge: quantification, experimentation, knowledge production are central in shaping contemporary states. These tools mobilize specific knowledges and experts, and put states in an ambiguous position. They are at the same time constrained by the technical infrastructure of the international interventions, and yet, they are able to manœuvre to affirm their positions, in particular on their population. These instruments create the condition of an ‘infiltration’: international donors, rather than impose conditions from the outside, now prefer to act from the inside through techniques, measures, standards, evaluation tools and a specific vocabulary. Los instrumentos de medida se volvieron herramientas centrales en el gobierno de la África contemporánea. Siguiendo el foco en la performance económica como herramienta de reforme de la ayuda al desarrollo y de los Estados, la medida genera nuevas modalidades de intervención (experimentación, cuantificación) y de reconfiguración política. Esas herramientas moviliazn expertos y saberes específicos y ponen los Estados en posición ambigua, a la vez coaccionados par estas infraestructuras técnicas de la acción política y manipulando también su margen de manobra para afirmarse sobre su población. Crean las condiciones de una infiltración donde los financieros internacionales más que imponer condiciones e intervenir desde afuera, se involucran en los Estados africanos a través de técnicas, medidas, estandarización, evaluación y una terminología especifica.

Estimating the gain of an antenna prototype is an important step during both design and validation phases. Nevertheless, many small technology companies and universities are not provided with adequate infrastructure to run this type of test. In this paper, we propose a computational tool to deal with undesirable contributions coming from non-ideal test conditions over electromagnetic measurements. It is based on auto-tunable filters and therefore it allows a lab technician to run the test without a major knowledge on signal processing. After a series of evaluations based on lab measurements, the proposed tool gives results as good as those provided by two other approaches but with a reduction of the total number of experimental runs. Furthermore, it is more efficient than the traditional time gating approach for low signal-to-noise ratio environments. Finally, a validation with different antennas and test sites confirmes its robustness.

International audience; Hydroacoustics has become a requisite method to assess fish populations and allows to describe the relationships of fish with other elements of the aquatic ecosystem. This nonintrusive method is currently an integral part of the sampling procedures recommended for fish stock assessment by the Water Framework Directive and has been standardized by the European Committee for Standardization [CEN (2014) CSN EN 15910 - Water quality - Guidance on the estimation of fish abundance with mobile hydroacoustic methods, Category: 7577 Water quality. Biological.]. In Europe, hydroacoustic surveys are performed in freshwater using different frequencies. Consequently, there is a need to evaluate if survey results can be compared. This study aimed to carry out in situ comparisons at the 38 kHz frequency (noted f) with two other commonly used frequencies, 70 and 200 kHz. The 38 kHz frequency has seldom been compared with other frequencies in freshwater although it is widely used worldwide, especially in the Great Lakes of North America and in Sweden. In 2016, hydroacoustic data were acquired in Lakes Annecy and Bourget using methods validated in previous studies that compared the frequencies 70, 120 and 200 kHz. This study showed similar density and biomass estimations as a function of frequency, density(f) and biomass(f), between the frequencies studied for low to moderate fish densities. For higher fish densities, the results were more variable and need to be verified. Fish density(f) and biomass(f) estimations sometimes exhibit differences between frequencies, which is not fully in agreement with theoretical calculations. The aim of this study was to evaluate frequency comparisons in practise. However, if the differences on acoustic metrics, density(f) or biomass(f) between frequencies were occasionally statistically significant, the differences were small enough to be considered negligible for fish population management. These analyses led to better knowledge of the responses from fish in temperate lakes for the studied frequencies. Our findings should be considered when revising the CEN standard.

In this paper, a multiple cracks monitoring system composed of a fiber optics cable and an interrogation unit based on Optical Backscattering Reflectometry technique is demonstrated. A mechanical strain transfer model is validated by performing an experimental test on a real scale reinforced concrete beam. The model is fitted to the strain spatial distributions, and the resulting parameters are discussed. Estimated crack openings are compared to those measured using traditional LVDT sensors and Digital Image Correlation (DIC) technique. Results show that this system, initially a strain monitoring system, can efficiently detect all multiple cracks, follow its propagation inside the structure, and more importantly monitor the surface and in-depth crack openings. The proposed multiple crack monitoring system will be of great help for early crack detection, as well as monitoring long-term degradation phenomenon like fatigue.

In this experimental study, statistical errors in the processing of raw Laser Doppler Velocimetry (LDV) data are discussed. Acquisitions have been made in an open-circuit wind tunnel in the wake flow of a simplified car model, for validation rates up to hundreds of Hertz. Both homogeneous and non-homogenous seeding conditions are considered. For homogeneous spatial concentration seeding, the velocity systematic error is presented regarding previous works. Correction methods are then discussed according to their assumptions. Then, this paper aims at characterizing the burst random error related to nonhomogeneous seeding. The experimental assessment of the available methods (interarrival time weighting and transit time weighting) according to the seeding conditions allows a deeper understanding of their ability to correct both velocity systematic error and burst random error. Finally, a new method is proposed mixing the previous one, leading to reliable (velocity systematic error correction) and repeatable (burst random error correction) results whatever the seeding conditions in our range of validation rates.; Dans cette étude expérimentale, les erreurs statistiques dans le traitement des données de vélocimétrie (LDV) sont discutées. Les acquisitions ont été faites dans une soufflerie en circuit ouvert dans le sillage d'un modèle de voiture simplifié, pour des taux de validation jusqu'à des centaines de Hertz.Les conditions d'ensemencement homogènes et non homogènes sont considérées. Pour l'ensemencement spatialement homogène, l'erreur systématique de vitesse est présentée en lien avec les travaux antérieurs. Les méthodes de correction sont ensuite discutées en fonction de leur hypothèses. Cet article vise à caractériser l'erreur aléatoire liée à l'hétérogénéité de l'ensemencement. L'évaluation expérimentale des méthodes disponibles permet une meilleure compréhension de leur capacité à corriger à la fois l'erreur systématique sur la vitesse et l'erreur aléatoire. Enfin, une nouvelle méthode est proposée, ce qui amène à des résultats répétables et fiable, quelles que soient les conditions d'ensemencement, dans notre gamme de mesure.

Cet article relate les étapes d’une recherche de développement didactique ayant mené à la création d’un outil informatique que nous avons nommé AnDIE, soit l’acronyme d’Analyse Didactique des Items avec Excel. Dans le cadre de cet article, nous montrons les différentes étapes qui nous ont permis de créer cet outil, basées sur le modèle de développement d’objet pédagogique de Van der Maren (1999). AnDIE vise à aider les apprenants à mieux comprendre les concepts et les techniques d’analyse de la théorie classique des tests. Dans cet article, il sera donc question de rendre compte de la démarche de conception de l’outil et de l’apport pédagogique et didactique de ce dernier dans un cours axé sur la mesure des apprentissages., This article describes the different steps of a didactic development research that led to the creation of a computer tool that we named AnDIE which is the acronym for Analyse Didactique des Items avec Excel. In this article, we show the different steps that allowed us to create this tool, based on the pedagogical object development model of Van der Maren (1999). AnDIE aims to help learners better understand the concepts and techniques of classical test theory. In this article, we will explain how we built the tool and how it can facilitate learning of classical test theory.

International audience; Due to their central role in ecosystems functioning and their ability to rapidly respond to environmental changes, soil microorganisms could potentially be used for monitoring ecosystems recovery in the context of degraded land restoration. However, these belowground organisms have been, to date, largely neglected. Here, we investigated fungal and bacterial community diversity, composition, and structure from ultramafic soils in New Caledonia, an archipelago in the southwest Pacific recognized as a priority for conservation and restoration. The emerging approach of high-throughput amplicon sequencing of environmental DNA (eDNA)-metabarcoding of eDNAwas used to compare soil microbial communities from four different native vegetation types, representing different stages of a chronosequence and defined as reference ecosystems, to five distinct post-mining sites revegetated several years ago. Our results clearly revealed changes in soil microbial phyla and functional groups along the reference chronosequence and variable responses at the different revegetated sites, with two of the five sites showing a good trajectory of recovery. We thus propose three ratios as metrics for monitoring the restoration trajectory of soil microorganisms: the Ascomycota:Basidiomycota and Saprotrophic:Ectomycorrhizal ratios for fungi, and the Cyanobacteria:Chloroflexi ratios for bacteria. Our study, combined with recent works undertaken in other geographical areas, underpins the great promise that could represent soil microbial eDNA metabarcoding for monitoring restoration progress and success. With the emergence of these new cost-effective and scalable sequencing technologies, soil microbes could, in the near future, be included in guidelines for restoration operations in complement to more conventional approaches.

International audience; The transparency of trees is the most important indicator for a forest health assessment. This paper presents an efficient method for calculating the crown transparency coefficient from tree binary images. This coefficient is based on the automated quantification of the deep indentation, macro-hole and micro-hole densities. Circular structuring elements are introduced, among other things, to automatically find the significant biological size. The symmetric tree convex hull and the tree smoothed contour are defined to delineate the reference areas necessary to evaluate the above-mentioned densities. Statistical thresholds are proposed to eliminate human operator subjectivity, especially in the automated identification of anatomical elements such as soft and deep crown-indentations or macro and micro crown-holes. A point-wise transparency map is produced to better appreciate the origin of the visible skylight areas in the crown. The crown micro-hole density is calculated from the 0.1-to-0.5 transparency points, the crown macro-hole density from the 0.5-to-1 transparency points. We finally opt for weighting of the above three densities with regard to the importance of the symptoms they describe for a more relevant crown transparency coefficient. A comparative study on several trees from full-size and half-size binary images showed that our method is similar overall to the DSO and less sensitive to scale reduction.

1. Irregularly shaped trees including trees with buttresses, flutes or stilt roots are frequent in tropical forests. The lack of an international standard to measure the diameter of such trees leads to high uncertainties in biomass estimation, tree growth and carbon budget monitoring. 2. In this study, we developed a new method based on terrestrial close-range photogrammetry for measuring and modelling irregular stems. This approach is cheap and easy to implement in the field as it only requires a camera and a graduated rod. We validated the approach with destructive cross-section measurements along the stem of three buttressed trees. To demonstrate the broader utility of this method, we extended the validated approach to 43 additional trees belonging to two species: Celtis mildbraedii (Ulmaceae) and Entandophragma cylindricum (Meliaceae). Based on the three dimensional models, we computed shape indices for each tree, and we analysed the stem morphology of the two species. Finally, we analysed some standardized predictors for the estimation of above-ground biomass. 3. We found a high concordance between diameters derived from the photogrammetric process and destructive diameter measurements along the stem for the three calibration trees. We found that C. mildbraedii develop much stronger irregularities than E. cylindricum. We also identified a large intraspecific variation in trunk morphology for E. cylindricum. The basal area at 1·3 m height (Darea130) seems to be a more robust predictor for biomass estimates (lowest Akaike information criterion and relative squared error) than diameter measured above buttresses (DAB) or diameter at breast height estimated from available taper model. Finally, Darea130 might be estimated with a good precision [root mean square error (RMSE) < 5%] with linear model based on the field measurements DAB and the perimeter of the convex hull of the buttresses at 1·3 m height (Dconvhull130). 4. In this study, we showed the high potential of the photogrammetry for measuring and modelling irregular stems. Photogrammetry could then be used as a non-destructive measurement tool to produce correction factors for standardizing the diameter of irregular stems at a reference height which is a key issue in tree growth monitoring and biomass change estimation. (Resume d'auteur)

International audience; The specificities of the plant environment and its effects on fungal growth are not yet fully explored. Both pH and Eh play a key role during this interaction, but are often studied independently or at different scales. We aimed at investigating whether the methods developed for the joint characterization of the pH and Eh in soil could be transposed to fungi. On artificial media, the growth of all 16 species tested significantly altered either Eh, pH or both. Measuring Eh reveals that even the species not modifying pH can have an impact on the surrounding environment. Reciprocally, fungi responded to pH and Eh parameters, both quantitatively with a decrease in colony diameter and qualitatively with colony aspect repeatedly and thoroughly modified. In infected oilseed rape plant stems, pH and Eh were significantly altered. The observed alcalinisation or acidification correlates with canker length. The joint characterization of both parameters will allow understanding the impact of fungi on their environment, and conversely of the environment on fungal growth. The availability of methods for measurement opens the prospect to study combinations of stresses, and get an understanding of the involvement of pH and Eh modifications in these interactions.

International audience; Monitoring the growth and body condition of cows is essential for optimal management of modern dairy farms. However, monitoring is rarely performed on commercial farms. Modern technologies based on three-dimensional (3D) shape analysis could address this problem. The objective of the present study was to test and validate tools that can record and analyze 3D body shapes of animals. On 30 Holstein dairy cows, wither height (WH), heart girth (HG), chest depth (CD), hip width (HW), backside width (BaW) and ischial width (IW) were manually measured. These manual measurements were compared to those measured with a scanner (Morpho3D) that provided 3D images of the entire cow body. Correlations between manual and Morpho3D measurements were high: 0.89 for CD, 0.82 for HW, 0.78 for HG, 0.76 for BaW, 0.63 for IW and 0.62 for WH. The mean coefficient of variation of reproducibility for Morpho3D was 2.8%. Future development can provide new opportunities for dairy herd management based on determining animal body volume and surface area.

Sound level predictions are based on both simplified emission and propagation models able to deal with transport and industrial sources only, thus neglecting other sound sources which yet contribute to urban soundscapes. Sound level assessment can take advantage of acoustic measurements if a sufficient amount of sensors is deployed to pick up the variety of sound sources. This can be achieved by combining fixed and mobile sensors that offer high temporal and spatial granularities respectively. The paper proposes a raw data processing protocol for comparing mobile with fixed measurements when the mobile sensors pass close to sound observatories. The statistical study is strengthened by a preliminary numerical analysis of the noise levels discrepancy between fixed and mobile sensors according to the location of the fixed station in relation to the facade.

International audience; The processes underlying environmental, economic, and social unsustainability derive in part from the food system. Building sustainable food systems has become a predominating endeavor aiming to redirect our food systems and policies towards better-adjusted goals and improved societal welfare. Food systems are complex social-ecological systems involving multiple interactions between human and natural components. Policy needs to encourage public perception of humanity and nature as interdependent and interacting. The systemic nature of these interdependencies and interactions calls for systems approaches and integrated assessment tools. Identifying and modeling the intrinsic properties of the food system that will ensure its essential outcomes are maintained or enhanced over time and across generations, will help organizations and governmental institutions to track progress towards sustainability, and set policies that encourage positive transformations. This paper proposes a conceptual model that articulates crucial vulnerability and resilience factors to global environmental and socio-economic changes, postulating specific food and nutrition security issues as priority outcomes of food systems. By acknowledging the systemic nature of sustainability, this approach allows consideration of causal factor dynamics. In a stepwise approach, a logical application is schematized for three Mediterranean countries, namely Spain, France, and Italy.

Upscaling instantaneous evapotranspiration retrieved at any specific time-of-day (ETi) to daily evapotranspiration (ETd) is a key challenge in mapping regional ET using polar orbiting sensors. Various studies have unanimously cited the shortwave incoming radiation (RS) to be the most robust reference variable explaining the ratio between ETd and ETi. This study aims to contribute in ETi upscaling for global studies using the ratio between daily and instantaneous incoming shortwave radiation (RSd ∕ RSi) as a factor for converting ETi to ETd.This paper proposes an artificial neural network (ANN) machine-learning algorithm first to predict RSd from RSi followed by using the RSd ∕ RSi ratio to convert ETi to ETd across different terrestrial ecosystems. Using RSi and RSd observations from multiple sub-networks of the FLUXNET database spread across different climates and biomes (to represent inputs that would typically be obtainable from remote sensors during the overpass time) in conjunction with some astronomical variables (e.g. solar zenith angle, day length, exoatmospheric shortwave radiation), we developed the ANN model for reproducing RSd and further used it to upscale ETi to ETd. The efficiency of the ANN is evaluated for different morning and afternoon times of day, under varying sky conditions, and also at different geographic locations. RS-based upscaled ETd produced a significant linear relation (R2 = 0.65 to 0.69), low bias (−0.31 to −0.56 MJ m−2 d−1; approx. 4 %), and good agreement (RMSE 1.55 to 1.86 MJ m−2 d−1; approx. 10 %) with the observed ETd, although a systematic overestimation of ETd was also noted under persistent cloudy sky conditions. Inclusion of soil moisture and rainfall information in ANN training reduced the systematic overestimation tendency in predominantly overcast days. An intercomparison with existing upscaling method at daily, 8-day, monthly, and yearly temporal resolution revealed a robust performance of the ANN-driven RS-based ETi upscaling method and was found to produce lowest RMSE under cloudy conditions. Sensitivity analysis revealed variable sensitivity of the method to biome selection and high ETd prediction errors in forest ecosystems are primarily associated with greater rainfall and cloudiness. The overall methodology appears to be promising and has substantial potential for upscaling ETi to ETd for field and regional-scale evapotranspiration mapping studies using polar orbiting satellites.

2018 International Conference on Indoor Positioning and Indoor Navigation, Nantes, France, 24-/09/2018 - 27/09/2018; International audience; In indoor environments, pedestrian dead reckoning (PDR) is the most used strategy for pedestrian position estimation from inertial data collected with handheld devices. PDR process recursively estimates positions using step length estimation based on parametric models that take into consideration some physiological parameters, displacement features and acceleration statistical properties. The coefficients of these models need frequent adjustment to limit cumulative errors induced by alteration of gait pattern. A large experimental database providing information about human locomotion variability is required for this calibration. However, the development of such database is costly in terms of time and effort. To make the collected data as reliable as possible, several gait-affecting factors should be considered, which highly increases the number of measurement trials. In this paper, we propose an alternative way of generating locomotion data that consists in simulating human walking gait motion under different conditions. We propose a multibody system simulator taking into account possible step-level asymmetry induced by handling a device in hand, as well as the correlation between arms and legs motions during gait. Our simulation approach was evaluated with data from overground walking experiments on one test subject. Preliminary results show some similarities between acceleration profiles related to different body parts, and the same variation trends of selected acceleration items in function of carrying mode and gait velocity.

Au cours des dernières décennies, de plus en plus d'applications de transport urbain basées sur les systèmes de positionnement par satellites (GNSS) ont vu le jour. Des applications exigent une fiabilité critique comme le télépéage basé sur l'utilisation du GNSS, pour lesquelles des erreurs de positionnement peuvent entraîner de graves conséquences. Pourtant, les environnements urbains présentent de grands défis pour le positionnement GNSS en raison de l'existence des trajets multiples et de signaux NLOS (None-Line-of-Sight). Cet article présente un système complet de surveillance de l'intégrité pour les applications de transport urbain. Tout d'abord, les erreurs de mesure sont mieux caractérisées en utilisant des modèles de pondération tirant parti d'un modèle de multi-trajet urbain (UMM). Deuxièmement, différentes méthodes de détection et d'exclusion de défauts (FDE) sont appliquées afin de détecter et d'exclure des mesures erronées. Enfin, les niveaux de protection horizontale (HPL) sont calculés et la probabilité d'événements redoutés (MI) est analysée., In the past decades, more and more Global Navigation Satellite Systems (GNSS)-based urban transport applications emerged. Among these applications, the liability critical ones, such as Electronic Toll Collection (ETC) and Pay as you Drive insurance, have high requirements for positioning accuracy as well as integrity since large errors can lead to serious consequences. Yet urban environments present great challenges for GNSS positioning due to the existence of multipath effects and None-Line-of-Sight (NLOS) receptions. This article presents a complete integrity monitoring scheme for urban transport applications. This scheme is realized in several levels. Firstly, measurement errors are better characterized by using weighting models with the help of an Urban Multipath Modeling (UMM). Secondly, several Fault Detection and Exclusion (FDE) methods are applied in order to detect and exclude erroneous measurements. Finally, Horizontal Protection Levels (HPLs) are computed and the probability of Misleading Information (MI) is analyzed.

International audience; The aim of this exploratory study was to examine whether the kurtosis metric can contribute to investigations of the effects of combined exposure to noise and solvents on human hearing thresholds. Twenty factory workers exposed to noise and solvents along with 20 workers of similar age exposed only to noise in eastern China were investigated using pure-tone audiometry (1000–8000 Hz). Exposure histories and shift-long noise recording files were obtained for each participant. The data were used in the calculation of the cumulative noise exposure (CNE) and CNE adjusted by the kurtosis metric for each participant. Passive samplers were used to measure solvent concentrations for each worker exposed to solvents over the full work shift. Results showed an interaction between noise exposure and solvents for the hearing threshold at 6000 Hz. This effect was observed only when the CNE level was adjusted by the kurtosis metric.; Le but de cette étude pilote était d’estimer la pertinence du kurtosis pour évaluer les effets d’une exposition combinée " bruit + solvants " sur les seuils auditifs de salariés. Vingt salariés exposés au bruit et à des solvants, et 20 salariés du même âge, exposés uniquement au bruit, ont été testés dans des entreprises présentes dans l’est de la Chine avec une audiométrie tonale (1000 - 8000 Hz). L’histoire acoustique et les postes occupés au cours de la carrière des salariés ont été obtenus pour chaque volontaire participant. Ces données ont été utilisées pour calculer l’exposition cumulée de bruit (CNE) et la CNE ajustée par le kurtosis. Des exposimètres passifs ont equipé les salariés pour mesurer les concentrations de solvants reçues sur leur poste entier. Les résultats ont montré qu’une interaction entre bruit et solvants existe pour le seuil auditif à la fréquence de 6 kHz. Les effets ont été observés uniquement lorsque que la CNE était ajustée par le kurtosis.

Time-of-flight measurement is a critical step to perform ultrasonic non-destructive testing of standing trees, with direct influence on the precision of defect detection. Aiming to increase the accuracy on the estimation, the characteristics of the ultrasonic measurement chain should be adapted to the constraints of wood testing in living condition. This study focused on the excitation signal parameters, 9 such as shape, temporal duration, and frequency response, and then the selection of a suitable time-of-flight determination technique. A standing plane tree was tested, placing ultrasonic receivers at four different positions, with five different excitation signals and three time-of-flight detection methods. The proposed ultrasonic chain of measurement resulted in 16 high signal-to-noise ratios in received signals for all configurations. A time-frequency analysis was used to determine the power distribution in the frequency domain, showing that only chirp signal could concentrate the power around the resonant frequency of the sensor. Threshold and Akaike information criterion method performed similar for impulsive signals with decreasing uncertainty as sensor position approached to the radial direction. Those two methods failed to accurate determine time-of-flight for Gaussian pulse and chirp signals. Cross-correlation was only suitable for the chirp signal, presenting the lower uncertainty values among all configurations.

Ce texte présente le projet européen SUSFANS., This paper defines the research agenda of the SUSFANS project, describes its history and its potential societal impacts. It contributes to balanced and encompassing views on how to strengthen food and nutrition security outcomes in the EU and how to improve the performance of the food system in the EU from the perspective of social, environmental and economic sustainability. The research is led by the notion that improvements in the diets of the European consumer must come from, and be supportive of, sustainable food systems. Its holistic, integrative approach builds a set of metrics, models and foresight tools, useable for navigation on sustainable food and nutrition security. This results in a coherent and supported vision on sustainable food and nutrition security in the EU and globally, and underpins a perspective on how EU policies on farming, fishing, food and nutrition could contribute to that vision with greater efficacy than today.

Global wheat production reached 754.8 million tons in 2017, according to the FAO database. While wheat is considered as a staple food for many populations across the globe, mapping wheat could be an effective tool to achieve the SDG2 sustainable development goal&mdash, End Hunger and Secure Food Security. In Lebanon, this crop is supported financially, and sometimes technically, by the Lebanese government. However, there is a lack of statistical databases, at both national and regional scales, as well as critical information much needed in the subsidy and compensation system. In this context, this study proposes an innovative approach, named Simple and Effective Wheat Mapping Approach (SEWMA), to map the winter wheat areas grown in the Bekaa plain, the primary wheat production area in Lebanon, in the years of 2016 and 2017. The proposed methodology is a tree-like approach relying on the Normalized Difference Vegetation Index (NDVI) values of four-month period that coincides with several phenological stages of wheat (i.e., tillering, stem extension, heading, flowering and ripening). The usage of the freely available Sentinel-2 imageries, with a high spatial (10 m) and temporal (5 days) resolutions, was necessary, particularly due to the small sized and overlapped plots encountered in the study area. Concerning the wheat areas, results show that there was a decrease from 11,063 &plusmn, 1309 ha in 2016 to 7605 &plusmn, 1184 in 2017. When SEWMA was applied using 2016 ground truth data, the overall accuracy reached 87.0% on 2017 data, whereas, when implemented using 2017 ground truth data, the overall accuracy was 82.6% on 2016 data. The novelty resides in executing early classification output (up to six weeks before harvest) as well as distinguishing wheat from other winter cereal crops with similar NDVI yearly profiles (i.e., barley and triticale). SEWMA offers a simple, yet effective and budget-saving approach providing early-season classification information, very crucial to decision support systems and the Lebanese government concerning, but not limited to, food production, trade, management and agricultural financial support.

International audience; Tropical forests are a key component of the global carbon cycle. Yet, there are still high uncertainties in forest carbon stock and flux estimates, notably because of their spatial and temporal variability across the tropics. Several upcoming spaceborne missions have been designed to address this gap. High-quality ground data are essential for accurate calibration/validation so that spaceborne biomass missions can reach their full potential in reducing uncertainties regarding forest carbon stocks and fluxes. The BIOMASS mission, a P-band SAR satellite from the European Space Agency (ESA), aims at improving carbon stock mapping and reducing uncertainty in the carbon fluxes from deforestation, forest degradation, and regrowth. In situ activities in support of the BIOMASS mission were carried out in French Guiana and Gabon during the TropiSAR and AfriSAR campaigns. During these campaigns, airborne P-band SAR, forest inventory, and lidar data were collected over six study sites. This paper describes the methods used for forest inventory and lidar data collection and analysis, and presents resulting plot estimates and aboveground biomass maps. These reference datasets along with intermediate products (e.g., canopy height models) can be accessed through ESA's Forest Observation System and the Dryad data repository and will be useful for BIOMASS but also to other spaceborne biomass missions such as GEDI, NISAR, and Tandem-L for calibration/validation purposes. During data quality control and analysis, prospects for reducing uncertainties have been identified, and this paper finishes with a series of recommendations for future tropical forest field campaigns to better serve the remote sensing community.

Spatially and temporally continuous estimation of plant photosynthetic carbon fixation (or gross primary production, GPP) is crucial to our understanding of the global carbon cycle and the impact of climate change. Besides spatial, seasonal and interannual variations, GPP also exhibits strong diurnal variations. Satellite retrieved solar-induced chlorophyll fluorescence (SIF) provides a spatially continuous, but temporally discrete measurement of plant photosynthesis, and has the potential to be used to estimate GPP at global scale. However, it remains unclear whether the seasonal time series of SIF snapshots taken at a fixed time of the day can be used to infer daily total GPP variation at spatial and seasonal scales. In this study, we first used GPP estimates from 135 eddy covariance flux sites, covering a wide range of geographic locations and biome types, to investigate the relationship between the instantaneous GPP (GPPinst) and daily GPP (GPPdaily) on the seasonal course for different times of the day. Latitudinal and diurnal patterns were found to correspond to variations in photosynthetically active radiation (PAR) and light use efficiency (LUE), respectively. We then used the Soil-Canopy Observation Photosynthesis and Energy Balance (SCOPE) model and the FluxCom GPP product to investigate the instantaneous and daily SIF-GPP relationships at five flux tower sites along a latitudinal gradient and at a global scale for different biome types. The results showed that daily SIF had a stronger linear correlation with daily GPP than instantaneous SIF at the seasonal scale, with an instantaneous to daily SIF conversion factor following the latitudinal and seasonal pattern driven by PAR. Our study highlights the necessity to take the latitudinal and diurnal factors into consideration for SIF-GPP relationship analyses or for physiological phenology analyses based on SIF.

International audience; West Africa is a region in fast transition from climate, demography, and land use perspectives. In this context, the African Monsoon Multidisciplinary Analysis (AMMA)-Couplage de l'Atmosphere Tropicale et du Cycle eco-Hydrologique (CATCH) long-term regional observatory was developed to monitor the impacts of global change on the critical zone of West Africa and to better understand its current and future dynamics. The observatory is organized into three thematic axes, which drive the observation and instrumentation strategy: (i) analyze the long-term evolution of eco-hydrosystems from a regional perspective; (ii) better understand critical zone processes and their variability; and (iii) meet socioeconomic and development needs. To achieve these goals, the observatory has gathered data since 1990 from four densely instrumented mesoscale sites (similar to 10(4) km(2) each), located at different latitudes (Benin, Niger, Mali, and Senegal) so as to sample the sharp eco-climatic gradient that is characteristic of the region. Simultaneous monitoring of the vegetation cover and of various components of the water balance at these four sites has provided new insights into the seemingly paradoxical eco-hydrological changes observed in the Sahel during the last decades: groundwater recharge and/ or runoff intensification despite rainfall deficit and subsequent re-greening with still increasing runoff. Hydrological processes and the role of certain key landscape features are highlighted, as well as the importance of an appropriate description of soil and subsoil characteristics. Applications of these scientific results for sustainable development issues are proposed. Finally, detecting and attributing eco-hydrological changes and identifying possible regime shifts in the hydrologic cycle are the next challenges that need to be faced.

Accurate and reliable estimates of gross primary productivity (GPP) are required for monitoring the global carbon cycle at different spatial and temporal scales. Because GPP displays high spatial and temporal variation, remote sensing plays a major role in producing gridded estimates of GPP across spatiotemporal scales. In this context, understanding the strengths and weaknesses of remote sensing-based models of GPP and improving their performance is a key contemporary scientific activity. We used measurements from 157 research sites (similar to 470 site-years) in the FLUXNET "La Thuile" data and compared the skills of 11 different remote sensing models in capturing intra- and inter-annual variations in daily GPP in seven different biomes. Results show that the models were able to capture significant intra-annual variation in GPP (Index of Agreement = 0.4-0.80) in all biomes. However, the models' ability to track inter-annual variation in daily GPP was significantly weaker (IoA < 0.45). We examined whether the inclusion of different mechanisms that are missing in the models could improve their predictive power. The mechanisms included the effect of sub-daily variation in environmental variables on daily GPP, factoring-in differential rates of GPP conversion efficiency for direct and diffuse incident radiation, lagged effects of environmental variables, better representation of soil-moisture dynamics, and allowing spatial variation in model parameters. Our analyses suggest that the next generation remote sensing models need better representation of soil-moisture, but other mechanisms that have been found to influence GPP in site-level studies may not have significant bearing on model performance at continental and global scales. Understanding the relative controls of biotic vis-a-vis abiotic factors on GPP and accurately scaling up leaf level processes to the ecosystem scale are likely to be important for recognizing the limitations of remote sensing model and improving their formulation. (C) 2015 Elsevier B.V. All rights reserved.

Categorization is a powerful method for describing urban sound environments. However, it has only been applied, until now, to discrete noise data collection, whereas sound environments vary continuously both in space and time. Therefore, a procedure is developed in this paper for describing the variations of urban sound environments. The procedure consists of mobile measurements, followed by a statistical clustering analysis that selects relevant noise indicators and classifies sound environments. Analysis are based on a 3 days + 1 night survey where geo-referenced noise measurements were collected over 19 1-h soundwalk periods in a district of Marseille, France. The clustering analysis showed that a limited subset of indicators is sufficient to discriminate sound environments. The three indicators that emerged from the clustering, namely, the Leq, A, the standard deviation σL eq, A, and the sound gravity spectrum SGC[50 Hz-10 kHz], are consistent with previous studies on sound environment classification. Moreover, the procedure proposed enables the description of the sound environment, which is classified into homogenous sound environment classes by means of the selected indicators. Thus, the procedure can be adapted to any urban environment, and can, for instance, favorably enhance perceptive studies by delimiting precisely the spatial extent of each typical sound environment.

International audience; Waste sorting activities are source of occupational bioaerosol exposures that are associated with several health disorders. New analytical tools, based on next generation sequencing (NGS) technologies, provide powerful methods to assess the microbial composition of bioaerosols. The objectives of the study were (1) to assess the feasibility and the repeatability of NGS based biodiversity measurements and (2) to study the microbial biodiversity using NGS in bioaerosols emitted in a waste sorting plant (WSP). Three stationary parallel samples were collected in a sorting cabin using closed-face cassettes equipped with polycarbonate membranes. Bacterial and fungal diversity was assessed by sequencing 16S and 18S rDNA genes using either Illumina sequencing or 454 pyrosequencing methods. At sampling point, airborne bacteria were dominated by Proteobacteria, Firmicutes and Actinobacteria with prevailing genera assigned to unclassified Enterobacteriaceae, Staphylococcus, Acinetobacter, Leuconostoc, Pseudomonas and Lactobacillus. Airborne fungi were dominated by Ascomycota with prevailing genera assigned to Penicillium, Aspergillus, Rhizopus,; Les activités de tri des déchets sont source d'expositions professionnelles aux bioaérosols et associées à plusieurs troubles de santé. De nouveaux outils analytiques, fondés sur des technologies de séquençage de nouvelle génération (NGS), fournissent des méthodes puissantes pour évaluer la composition microbienne des bioaérosols. Les objectifs de l'étude étaient (1) d'évaluer la faisabilité et la répétabilité des mesures de biodiversité basées sur la NGS et (2) d'étudier la biodiversité microbienne en utilisant des NGS dans les bioaérosols émis dans une usine de tri de déchets (UTD). Trois échantillons parallèles ont été prélevés en ambiance dans une cabine de tri à l'aide de cassettes fermées équipées de membranes en polycarbonate. La diversité bactérienne et fongique a été évaluée par séquençage des gènes d'ADNr 16S et 18S en utilisant des séquenceurs Illumina ou 454-pyrosequenceur. Au niveau du point d'échantillonnage, les bactéries aéroportées étaient dominées par les Proteobacteria, les Firmicutes et les Actinobacteria avec des genres dominants assignés à des Enterobacteriaceae non classifiés, Staphylococcus, Acinetobacter, Leuconostoc, Pseudomonas et Lactobacillus. Les champignons aéroportés étaient dominés par des Ascomycota avec des genres prédominants attribués à Penicillium, Aspergillus, Rhizopus, Wallemia et Hemicarpenteles. Les mesures de la biodiversité NGS ont révélé une biodiversité plus élevée par rapport aux données publiées, obtenue avec la méthode par culture suivie d'une identification de microorganismes. Ces résultats constituent les premières données concernant la biodiversité dans les bioaérosols des UTD et obtenus en utilisant le séquençage à haut débit.

Climate-smart approaches have gained momentum in tropical, agricultural development. However, to date, few studies have examined whole-farm greenhouse gas (GHG) balances in smallholder crop-livestock systems. This study aimed to quantify GHG balances at farm-scale, identify GHG hotspots and assess mitigation options in coffee-dairy farms undergoing agricultural intensification in Central Kenya. In recent decades, decreasing farm size has forced the shift from extensive practices to zero-grazing systems and higher nitrogen (N) inputs. We hypothesised that different farm strategies and intensification levels determine the farm’s GHG balance. A farm typology was constructed through principal component analysis (PCA) and hierarchical clustering from 125 farms surveyed. Four farm types were identified ranging relatively from small to large farms, low to high livestock intensities, and low to high N input rates. Whole-farm GHG balances were estimated using an adapted version of the Cool Farm Tool (CFT). Farms were found to be net sources of GHG, averaging from 4.5 t CO 2 eq ha −1 yr −1 in less intensive farms to 12.5 t CO 2 eq ha −1 yr −1 in high intensive farms. Within the farm GHG hotspots identified, methane (CH 4 ) from enteric fermentation processes accounted for 26–39% of total farm GHG emissions; nitrous oxide (N 2 O) and CH 4 from manure management systems (MMS) for 26–38%; soil background and fertilizer induced N 2 O emissions for 24–29%; off-farm production of feeds and agrochemicals for 10–22%; and crop residue management (CRM) for the remaining 1–3%. Within the mitigation practices assessed, zero-grazing stalls already lowered the livestock maintenance energy requirements, reducing enteric fermentation emissions. Stall-feeding, however, brings the necessity-opportunity to manage the manure and our results showed that MMS can be a determining factor in the GHG balance. Increasing the frequency of manure collection from stalls in favour of solid storage systems can reduce N 2 O emissions by up to 75%. Furthermore, dry manure storage reduced the CH 4 emissions of liquid slurry systems by more than 70%. Further benefits in terms of carbon (C) sequestration were identified along farm types from manure and crop residues applications in soils (with averages of −1.3 to −2.3 t CO 2 eq ha −1 yr −1 ) and biomass growth in agroforestry systems (−1.2 to −2 t CO 2 eq ha −1 yr −1 ). Together, soils and woody biomass offset 25–36% of farm emissions. We conclude that reduced farm size and increased livestock density lead to higher emissions per unit area, though this increase is smoothed by larger negative fluxes in soils (by higher C inputs) and woody biomass (by higher tree densities) until a steady state is reached. Average yield-scaled emissions, or product carbon footprints (CFs), resulted in 1.08 kg CO 2 eq kg coffee berry −1 , 0.64 kg CO 2 eq kg maize −1 and 1.05 kg CO 2 eq kg milk −1 on average. CFs did not always differ between farm types and intensification levels, meaning that increases in productivity were not higher than increases in GHG fluxes from intensification. This may be due to: 1) increases in productivity are the result of more processes other than N inputs; and/or 2) emissions from N inputs are overestimated by EFs and GHG calculators. Smallholders may benefit in the near future from climate initiatives and further field characterisation, models calibration and monitoring are required to overcome critical levels of uncertainty and provide more accurate estimations of GHG balances at farm-scale.

When managing a sewer network, the water discharge has to be measured in real time at several locations in the network. In locations where a simple stage discharge relationship cannot be applied due to an influence of the backwater curve, this measurement is to be performed using sensors that measure the bulk velocity locally in order to estimate the discharge. The aim of this work is to quantify the errors made when such measurement is performed downstream from two types of singularities: a bend and a confluence, which are commonly encountered in sewer networks. Two types of sensors are tested: a time-of-flight flow meters and a acoustic Doppler flowmeter. Both technologies are first detailed along with their possible sources of errors when used in the vicinity of singularities. The second section then introduces the numerical calculation of all flow configurations tested downstream both kinds of singularities. The third section shows the results in terms of error of discharge estimation as a function of the location with regards to the singularities, the type of singularity and the flow conditions. This permits to finally make recommendations for the use of such sensors in a real sewer network.; Les gestionnaires de réseau d'assainissement urbain sont amenés à équiper leurs réseaux de points de mesures débimétriques. Lorsqu'une relation permanente permettant de relier localement la hauteur d'eau et le débit n'existe pas, il est nécessaire de mesurer la vitesse moyenne de l'écoulement afin d'en déduire le débit localement. L'objectif de cet article est de quantifier les erreurs faites lorsqu'une mesure de vitesse est effectuée à l'aval d'une singularité pour des situations réalistes de collecteurs d'assainissement urbain. La première section de cet article présente les deux types de capteurs (cordes et Doppler) en détaillant leur mode d'échantillonnage spatial ainsi que les sources d'erreur associées. La deuxième section présente la démarche de modélisation numérique ainsi que les domaines de calcul associés à l'aval respectivement d'une confluence et d'un coude. Enfin la troisième partie présente les résultats en termes de réponse des capteurs à ces champs de vitesse et discute les erreurs pour les différentes configurations considérées.

In the assessment of standing trees, an acoustic tomographic device is a valuable tool as it permits to acquire data from the inner part of the trees without causing them to fall down unnecessarily. The interpretation of the images produced by these devices is part of the diagnosis process for urban trees management. This paper presents a segmentation methodology to identify defective regions in cross-section tomographic images obtained with an Arbotom® device. Two trunk samples obtained from a Blackwood Acacia tree (Acacia melanoxylon) were tested, simulating defects by drilling holes with known geometry, size and position and using different numbers of sensors. Tomograms from the trunk cross sections were processed to align the propagation velocity data with the corresponding region, either healthy or defective. The segmentation methodology proposed aims to find a velocity threshold value to separate the defective region adjusting a logistic regression model to obtain the value that maximizes a performance criterion, using in this case the geometric mean. Two criteria were used to validate this methodology: the geometric mean and the surface ratio detected. Although an optimal threshold value was found for each experiment, this value was strongly influenced by the defect characteristics and the number of sensors. The correctly segmented area ranging from 54 to 93% demonstrates that the threshold method is not always the most proper way to process this type of images, and thereby further research is required in image processing and analysis.

International audience; In this work, we consider a one-dimensional Itô diffusion process X t with possibly nonlinear drift and diffusion coefficients. We show that, when the diffusion coefficient is known, the drift coefficient is uniquely determined by an observation of the expectation of the process during a small time interval, and starting from values X 0 in a given subset of R. With the same type of observation, and given the drift coefficient, we also show that the diffusion coefficient is uniquely determined. When both coefficients are unknown, we show that they are simultaneously uniquely determined by the observation of the expectation and variance of the process, during a small time interval, and starting again from values X 0 in a given subset of R. To derive these results, we apply the Feynman-Kac theorem which leads to a linear parabolic equation with unknown coefficients in front of the first and second order terms. We then solve the corresponding inverse problem with PDE technics which are mainly based on the strong parabolic maximum principle.

Soil is a key compartment for climate regulation as a source of greenhouse gases (GHGs) emissions and as a sink of carbon. Thus, soil carbon sequestration strategies should be considered alongside reduction strategies for other greenhouse gas emissions. Taking this into account, several international and European policies on climate change are now acknowledging the importance of soils, which means that proper, comparable and reliable information is needed to report on carbon stocks and GHGs emissions from soil. It also implies a need for consensus on the adoption and verification of mitigation options that soil can provide. Where consensus is a key aspect, formal standards and guidelines come into play. This paper describes the existing ISO soil quality standards that can be used in this context, and calls for new ones to be developed through (international) collaboration. Available standards cover the relevant basic soil parameters including carbon and nitrogen content but do not yet consider the dynamics of those elements. Such methods have to be developed together with guidelines consistent with the scale to be investigated and the specific use of the collected data. We argue that this standardization strategy will improve the reliability of the reporting procedures and results of the different climate models that rely on soil quality data.

This article introduces the h2Q method. This method allows the determination of the discharge in sewer pipe thanks to two water level measurements. Investment and operating costs are limited for this technique because it only involves contactless sensors. A backwater curve model is used to generate a three column table (h1, h2, Q) involving the upstream water depth, the downstream water depth and the discharge. Without calibration, this method leads to an uncertainty evaluated to 30%. With calibration, the uncertainty decreases to about 15%, which is comparable to the other technologies available on the market (when they are installed in good conditions). Two on-site applications are presented in order to validate the method and demonstrate that it is operational.; La méthode h2Q présentée dans cet article permet la détermination du débit en collecteur uniquement à partir de deux mesures de niveau d'eau réalisées à l'amont et à l'aval d'un tronçon de quelques dizaines de mètres. Ceci en fait une méthode peu coûteuse à l'investissement et à l'exploitation puisqu'elle ne met en oeuvre que des capteurs sans contact qui ne nécessitent que peu de maintenance par rapport à des capteurs immergés. La méthode h2Q repose sur la génération à partir du modèle de la courbe de remous d'un tableau de valeurs (h1, h2, Q) mettant en relation la hauteur amont, la hauteur aval et le débit. Mise en oeuvre sans calage, elle permet l'évaluation du débit avec une incertitude de l'ordre de 30%. Un calage permet de réduire, l'incertitude à environ 15%, soit une valeur comparable aux autres technologies disponibles sur le marché lorsqu'elles sont mises en place conformément aux règles de l'art. Une validation de la méthode sur deux sites de mesure grandeur nature est présentée afin de démontrer son caractère opérationnel.

Combined sewer networks display some unique features that are not easily reproducible in the laboratory and have yet to be well understood. The transport of organic and mobile sediments, present in large quantities despite the use of optimal design practices, dramatically changes sewer flow patterns and the interaction between flow and sediment. To understand both the flow patterns and transport features of these complex environments, it is therefore necessary to install instrumentation in situ. For this paper, two distinct acoustic techniques were coupled in order to measure both the sediment interface and velocity. For this purpose, a 2 MHz rotating head acoustic profiler and a 10 MHz acoustic Doppler velocimeter (ADV) were jointly installed to survey the position of sediment deposits and measure velocity patterns. Results were compared with measurements recorded in different environments, where both coarser and finer soft deposits were present. These results typically showed good agreement between the interfaces detected using velocity measurements on coarse deposits, while the presence of soft deposits demonstrated the need for coupling measurements techniques that can correctly assess the sediment interface.

A compact UWB bowtie-slot antenna (36 multiplied by 23 cm2) fed by a CPW transition is proposed for an improved ground-coupling radar. The antenna has an operating frequency band in the range [0.46 ; 4] GHz. Full-wave modeling using the FDTD approach has allowed to study in details the antenna radiation characteristics in air and in the presence of a soil. Afterwards, a radar system made of a pair of independent shielded bowtie antennas has been considered to probe the sub-surface very close to the air-soil interface. The polarization diversity in the E and H-planes is an important aspect which has been studied in order to further detect the orientation of damages (cracks, delaminations . . . ) in civil engineering structures. Measurements in a dry and wet sand in different system configurations have allowed to first characterize the GPR system and to draw comparisons with numerical results. The ability of the radar to detect small buried objects has been investigated.; Une antenne noeud papillon "bowtie" à encoche ULB compact (36 fois 23 cm2) alimentée par une transition CPW est proposée pour améliorer le couplage du radar au sol. L'antenne a une bande de fréquences de fonctionnement dans la plage [0.46 ; 4] GHz. Une modélisation "full-wave" utilisant l'approche FDTD a permis d'étudier en détail les caractéristiques de rayonnement de l'antenne dans l'air et en présence d'un sol. Par la suite, un système radar formé d'une paire d'antennes bowtie blindées et indépendantes a été considéré pour sonder la sub-surface très proche de l'interface air-sol. La diversité de polarisation dans les plans E et H est un aspect important qui a été étudié afin de détecter par la suite l'orientation des défauts (fissures, décollements ...) dans les structures de génie civil. Des mesures dans un sable sec et humide dans différentes configurations du système radar ont permis de caractériser le système GPR et d'établir des comparaisons avec les résultats numériques. La capacité du radar à détecter les petits objets enfouis a été étudiée.

APEC 2012 - IEEE Applied Power Electronics Conference and Exposition, Orlando, ETATS-UNIS, 05-/02/2012 - 07/02/2012; The measurement of the junction temperature with thermo-sensitive electrical parameters (TSEPs) is largely used by electrical engineers or researchers but the obtained temperature value is generally not verified by any referential information of the actual chip temperature distribution. In this paper, we propose to use infrared (IR) measurements in order to evaluate the relevance of three commonly used TSEP with IGBT chips: the saturation voltage under a low current, the gateemitter voltage and the saturation current. The IR measurements are presented in details with an estimation of the emissivity of the black paint deposited on the power module. The temperatures obtained with IR measurement and with the different TSEPs are then compared in two cases: the use of only one chip and the use of two paralleled chips.

The research question is based on demonstration of the existence of a recent channel incision by the Niger river in the upper part of its course (upstream of Ségou, Mali), running contrary to the opinion that silting is in progress, a view being shared by the technical agencies involved in the management of the basin. The hypothesis is supported by diachronic topometric observations: surveys of cross sections of the low flow channel, depth mapping of the Sélingué dam reservoir and also by examination of the evolution of the rating curve at Koulikoro gauging station, one of the oldest in West Africa. An incision tendency is clear since the early 1980s. The main reason is human and related to the extraction of building materials for Bamako. This extraction is combined with small longitudinal drift. The sedimentary imbalance has immediate socioeconomic consequences.; La problématique de recherche est fondée sur la mise en lumière d'une incision récente du fleuve Niger dans sa partie supérieure (en amont de Ségou) contrairement à l'opinion généralement exprimée, y compris par les services techniques concernés par la gestion du bassin, d'un ensablement effectif. L'hypothèse est étayée par les résultats de mesures topométriques diachroniques : levés de profils transversaux du lit mineur, cartes bathymétriques du réservoir de barrage de Sélingué, et aussi par l'examen de l'évolution de la courbe de tarage de la station hydrométrique de Koulikoro, l'une des plus anciennes d'Afrique de l'Ouest. Une tendance à l'incision est manifeste depuis le début des années 80, dont la raison est essentiellement anthropique, liée à l'extraction de matériaux pour l'industrie du bâtiment à Bamako. A ces prélèvements se conjuguent la faiblesse des apports longitudinaux. Le déséquilibre sédimentaire a des conséquences socio-économiques immédiates.

The high temporal and spatial granularities recommended by the European regulation for the purpose of environmental noise mapping leads to consider new alternatives to simulations for reaching such information. While more and more European cities deploy urban environmental observatories, the ceaseless rising number of citizens equipped with both a geographical positioning system and environmental sensors through their smartphones legitimates the design of outsourced systems that promote citizen participatory sensing. In this context, the OnoM@p system aims at offering a framework for capitalizing on crowd noise data recorded by inexperienced individuals by means of an especially designed mobile phone application. The system fully rests upon open source tools and interoperability standards defined by the Open Geospatial Consortium. Moreover, the implementation of the Spatial Data Infrastructure principle enables to break up as services the various business modules for acquiring, analysing and mapping sound levels. The proposed architecture rests on outsourced processes able to filter outlier sensors and untrustworthy data, to cross- reference geolocalised noise measurements with both geographical and statistical data in order to provide higherlevel indicators, and to map the collected and processed data based on web services.

International audience; Phenotypic traits and their associated trade-offs have been shown to have globally consistent effects on individual plant physiological functions1, 2, 3, but how these effects scale up to influence competition, a key driver of community assembly in terrestrial vegetation, has remained unclear4. Here we use growth data from more than 3 million trees in over 140,000 plots across the world to show how three key functional traits-wood density, specific leaf area and maximum height-consistently influence competitive interactions. Fast maximum growth of a species was correlated negatively with its wood density in all biomes, and positively with its specific leaf area in most biomes. Low wood density was also correlated with a low ability to tolerate competition and a low competitive effect on neighbours, while high specific leaf area was correlated with a low competitive effect. Thus, traits generate trade-offs between performance with competition versus performance without competition, a fundamental ingredient in the classical hypothesis that the coexistence of plant species is enabled via differentiation in their successional strategies5. Competition within species was stronger than between species, but an increase in trait dissimilarity between species had little influence in weakening competition. No benefit of dissimilarity was detected for specific leaf area or wood density, and only a weak benefit for maximum height. Our trait-based approach to modelling competition makes generalization possible across the forest ecosystems of the world and their highly diverse species composition.

Assessing the spatial variability of soil organic carbon (SOC) is crucial for SOC monitoring and comparing management options. Topsoil (0–5 cm) SOC concentrations were surveyed in a coffee agroforestry watershed (0.9 km2) on Andisols in Costa Rica with uniform farm management. We encountered high values and large spatial variations of SOC, from 48.1 to 172 g kg− 1 in the dry combustion set (SOCref; n = 72) used for calibrating the visible-near-infrared reflectance spectroscopy (VNIRS) samples (SOCVNIRS; 350–2500 nm; n = 520). VNIRS using partial least squares regression was effective in predicting SOC (R2 = 0.85; a root mean square error (RMSE) = 12.3 g kg− 1) and proved an effective proxy measurement. We assessed several topographic, vegetation and andic soil property variables, of which only the latter (metal–humus complexes and allophanes) displayed strong correlations with SOCref concentrations. We compared Random Forest and three geostatistical approaches for the interpolation of SOC in unsampled locations. Ordinary kriging with SOCref yielded an RMSE of 28.0 g kg− 1. Random Forest was successful in incorporating many weakly and non-linearly correlated covariates with SOC (RMSE = 14.7 g kg− 1), provided Alp (the sodium pyrophosphate extractable aluminum), the best predictor of SOC (r = 0.85) but also the most costly variable to acquire. Co-kriging with Alp also showed high reduction in RMSE (16.0 g kg− 1). Co-kriging with SOCVNIRS only showed marginal reduction in RMSE to 24.2 g kg− 1 due to the presence of a high nugget effect. Local variability of SOC in this volcanic agroforestry watershed was dominated by andic properties whereas topographic or vegetation variables had very little impact. Estimation of SOC variability is recommended using inexpensive proxy measurements like VNIRS (RMSE = 12.3 g kg− 1) rather than spatial interpolation techniques. (Resume d'auteur)

International audience; Challenging evaluation of tropical forest biodiversity requires the reporting of taxonomic diversity but also the systematic characterization of wood properties in order to discover new promising species for timber industry. Among wood properties, the dimensional stability is regarded as a major technological characteristic to validate whether a wood species is adapted to commercial uses. Cell structure and organization are known to influence the drying shrinkage making wood density and microfibrils angle markers of choice to predict wood dimensional stability. On the contrary the role of wood extractive content remains unclear. This work focuses on the fast-growing tropical species Bagassa guianensis and we report herein a correlation between heartwood drying shrinkage and extractive content. Chemical extractions and shrinkage experiments were performed on separate wood twin samples to better evaluate correctly how secondary metabolites influence the wood shrinkage behaviour. Extractive content were qualitatively and quantitatively analysed using HPLC and NMR spectroscopy. We found that B guianensis heartwood has a homogeneous low shrinkage along its radius that could not be explained only by its basic density. In fact the low drying shrinkage is correlated to the high extractive content and a corrected model to improve the prediction of wood dimensional stability is presented. Additionally NMR experiments conducted on sapwood and heartwood extracts demonstrate that secondary metabolites biosynthesis occurs in sapwood thus revealing B. guianensis as a Juglans-Type heartwood formation. This work demonstrates that B. guianensis, a fast-growing species associated with high durability and high dimensional stability, is a good candidate for lumber production and commercial purposes.

This paper presents the design of a novel Ground-Penetrating Radar (GPR) test site that has been integrated into the mini-city demonstrator Sense-City located at University Paris-Est (France). This test site provides several sources of measurement interest expressed by the presence of a multilayered soil with significant dielectric contrasts, and various dielectric pipes and blades buried at various depths in trenches filled with a backfill soil different from the natural soil. This paper presents experimental Bscans associated with the pipe zone acquired by three different GPR systems at frequencies ranging from 300 MHz to 1.5 GHz. The interpretation and comparison of the raw Bscans have allowed to characterize the dielectric properties of the soil layers, and to detect the hyperbola signatures of the buried pipes. The results of this study will help to guide future developments on polarization, operating frequency and signal processing to extract parameters (orientation, dielectric characteristics, position and size) associated with pipes.

International audience; European Community policy concerning water is placing increasing demands on the acquisition of information about the quality of aquatic environments. The cost of this information has led to a reflection on the rationalization of monitoring networks and, therefore, on the economic value of information produced by these networks. The aim of this article is to contribute to this reflection. To do so, we used the Bayesian framework to define the value of additional information in relation to the following three parameters: initial assumptions (prior probabilities) on the states of nature, costs linked to a poor decision (error costs) and accuracy of additional information. We then analyzed the impact of these parameters on this value, particularly the combined role of prior probabilities and error costs that increases or decreases the value of information depending on the initial uncertainty level. We then illustrated the results using a case study of a stream in the Bas-Rhin department in France.

International audience; Soil CO2 flux (Fs) can be measured either manually or automatically. While manual measurements are well suited to capture the spatial variability of Fs, automated measurements are able to capture its temporal variability at fine time scales. The manual method is the most commonly used method to estimate annual carbon budgets. However, such estimates can be biased depending on the measurement frequency, the time at which measurements are made, and the method used to interpolate Fs between two measurements. In this study, we investigated the effects of within-day measurement frequency and of the time of measurement on the estimation of daily Fs. We also investigated the effects on cumulative Fs estimates of weekly and fortnightly sampling frequencies over several months and of the interpolation method used to cumulate Fs. We based our analyses on two complete datasets of automated measurements (one 12-month and one 4-month) recorded in two contrasting ecosystems (a tropical eucalypt plantation and a temperate poplar plantation). Low-frequency time step within a day (every 360 min for the eucalypt and every 180 min for the poplar plantations) was sufficient to capture mean daily Fs accurately. Furthermore, in the tropical site, measurements averaged over any 6h period provided good estimates of the daily flux. By contrast, biases were observed in the temperate site. With one measurement per week, linear interpolation methods provided accurate cumulative fluxes at both sites. However, all interpolation methods failed to produce robust estimates of cumulative Fs in the temperate plantation with one measurement every two weeks. Automated measurements will help to select the best time slot for manual measurements or to correct manual measurements from the apparent deviation between measurements collected during the sampling period and the 24 h-mean CO2 flux. It will also be useful to elaborate empirical equations used to cumulate Fs obtained manually. Combining manual and automated methods will enhance the accuracy of annual soil carbon budgets in forest plantations.

Recurrent food crises and global change are critical issues that pushed food security and environmental sustainability to the top of the political agenda. Using the lens of a broad sustainability approach and recognizing the systemic dimension of sustainability, the thesis developed a multidimensional framework to identify metrics for assessing the sustainability of food systems and diets. Building on the theories of vulnerability and resilience, the Mediterranean Region presents a set of socioeconomic and biophysical drivers of change affecting the sustainability of the food system in its main functions providing food and nutrition security. Formalizing the food system as a dynamic complex system, several causal models of vulnerability were identified, describing the interactions where drivers of change directly affect food and nutrition security outcomes, disentangling exposure, sensitivity, and resilience. This theoretical approach was operationalized through the identification of a first suite of indicators. A reduced pool of metrics was then obtained through an expert-based Delphi survey, moving beyond subjective evaluation and reaching consensus., Italian Review of Agricultural Economics, Vol 71 No 1 (2016): Vol 71, No 1 (Suppl.) (2016)

L'évaluation environnementale des politiques publiques nécessite la mise en place de suivis de biodiversité à différentes échelles. La mesure de biodiversité est toujours partielle, elle est délicate à réaliser et de nombreux facteurs sont susceptibles d'en détériorer significativement la qualité. Il est donc indispensable de considérer ces différents facteurs lors de la planification des suivis de façon à en minimiser l'impact et à pouvoir les prendre en compte lors de l'analyse. Il semble important de continuer à progresser vers la standardisation des protocoles d'inventaires et in fine l'établissement de normes. / Biodiversity monitoring programs are increasingly needed to assess the environmental impact of public policies at different scales. Yet only a fraction of biodiversity is usually monitored; measuring biodiversity is complicated; many factors are likely to reduce the quality of the measure. Thus, it is mandatory to consider these factors when planning a monitoring as to reduce their impact and to take them into account in the analyses. It seems important to progress towards standardised protocols and norms.