Calibration of an Active Ultrasound Bedload Monitoring System for Underwater Environments

International audienceThis paper introduces the concept of coupling ul-trasound transducers with piezoelectric accelerometers for active ultrasound bedload monitoring in underwater environments. A general system calibration procedure is proposed which allows the enduser to establish a real-time link between the energy of the received signals and the bedload transport phenomena

Construction et analyse des signaux non-stationnaires adaptés à la caractérisation des phénomènes turbulents

National audienceDans ce papier nous proposons une approche hybride signal-physique pour la détection de la présence de la turbulence dans un fluide. L'idée est de construire une forme d'onde capable de porter, de manière robuste, l'information sur la turbulence et de mettre en place le traitement qui permettra l'extraction des paramètres liés à ce phénomène. Il est donc nécessaire de réaliser une correspondance entre les grandeurs qui caractérisent les écoulements turbulents et les signaux acoustiques. Nous allons montrer que l'utilisation des signaux avec une loi de fréquence instantanée polynomiale est potentiellement porteuse de l'information de turbulence que nous pouvons extraire à partir de l'estimation de la déformation de cette loi

Time-Frequency characterisation for electric load monitoring

Electric utilities and consumers are increasingly interested in energy monitoring for economic and environmental reasons. A non-intrusive solution may rely on information extracted from the electric consumption measured at a centralized part of a distribution network. The problem at hands consists in the separation of the electric load into its major components. This problem of source separation from one sensor is quite tractable under certain conditions. In this work, the focus is made on the most consuming household appliance in France: the space-heating. It is a sum of an unknown number of pseudo-periodic signals embedded in the global active power. An unsupervised algorithm to determine the space-heating schedule from the global consumption based on the interpretation of the spaceheating signature in the time-frequency domain is proposed. The proposed method conjoins a time-frequency detector and a frequent itemsets extraction. First results on real data are quite satisfying

Reference Selection for an Active Ultrasound Wild Salmon Monitoring System

International audienceThis paper introduces the concept of automatic reference selection for active ultrasound wild salmon monitoring systems in turbulent underwater environments. A general in situ calibration procedure is proposed which allows grate improvements in terms of fish detection, identification and tracking capabilities

Potential of Active Ultrasound Monitoring Systems for Jellyfish Detection

International audienceThis paper investigates the potential of active ultrasound jellyfish monitoring systems to continuously detect, quantify and identify different species in turbulent underwater environments. The experimentations carried out in December 2015 at the Aquarium de Paris, France, are used to propose an unified acoustic signal processing framework for visualizing jellyfish passages

Monitoring and early detection of internal erosion: Distributed sensing and processing

International audienceEarly detection of leakages in hydraulic infrastructures is important to ensure their safety and security. Significant flow of water through the dike can be an indicator of internal erosion and results in a thermal anomaly. Temperature measurements are therefore capable of revealing information linked to leakage. Optical fiber-based distributed temperature sensors present an economically viable and reliable solution for recording spatio-temporal temperature data over long distances, with spatial and temperature resolutions of 1m and 0.05 C, respectively. The acquired data are influenced by several factors, among them water leakages, heat transfer through the above soil depth, seasonal thermal variations, and the geomechanical environment. Soil properties such as permeability alter the acquired signal locally. This article presents leakage detection methods based on signal processing of the raw temperature data from optical fiber sensors. The first approach based on source separation identifies leakages by separating them from the non-relevant information. The second approach presents a potential alarm system based on the analysis of daily temperature variations. Successful detection results for simulated as well as real experimental setups of Electricité de France are presented

Independent component analysis within polarimetric incoherent target decomposition

International audienceThis paper represents a part of our efforts to generalize polarimetric incoherent target decomposition to the level of BSS techniques by introducing the ICA method instead of the conventional eigenvector decomposition. We compare, in the frame of polarimetric incoherent target decomposition, several criteria for the estimation of complex independent components. This is done by parametrising the obtained dominant and mutually independent target vectors using the TSVM and representing them on the corresponding Poincare sphere. We demonstrate notably good performances of the proposed method applied on the RAMSES POLSAR X-band image, by precisely identifying the class of trihedral reflectors present in the scene. Logarithm and square root nonlinearities - two of the three proposed criteria for complex IC derivation prove to be very efficient. The best discrimination between the a priori defined classes appears to be achieved with the principal kurtosis criterion. Finally, the algorithm using the former two functions leads to very interesting entropy estimation

Wet snow backscattering sensitivity on density change for SWE estimation

International audienceThis paper deals particularly with the sensitivity of the wet snow backscattering coefficient on density change. The presented backscattering model is based on the approach used in the dry snow analysis, appropriately modified to account for the increased dielectric contrast caused by liquid water presence. It encircles our undertaking of simulating and analysing snow backscattering using fundamental scattering theories (IEM-B, QCA, QCA-CP). The wet snow parameters are chosen according to the area of the particular interest - the French Alps, while the choice of the SAR sensor parameters (frequency, polarization) is primarily conditioned by the initially settled goal - reaching qualitative conclusions concerning wet snow backscattering mechanism. Based on simulation results, we state the dominance of the snow pack surface backscattering component, causing the backscattering to be directly proportional to the volumetric liquid water content. This result is confirmed by the performed in situ measurements. We illustrate as well the decrease of this effect with the increase in operating frequency

Unconstrained Nonlinear Optimization of a Distributed SWE Model Using Modis and In Situ Measurements Over the French Alps

International audienceIn this paper we propose the optimization of the snow sub-model of MORDOR using MODIS and in situ measurements for the case study of the Serre-Ponçon reservoir (one of the largest artificial lakes in Western Europe) on the Durance River in the French Alps. We consider the problem of optimizing the snow model as an unconstrained nonlinear optimization problem