Analyse des signaux transitoires émis par les arcs électriques générés dans les panneaux photovoltaïques

National audienceDes arcs électriques aux conséquences graves peuvent parfois survenir au sein de panneaux photovoltaïques. Cet article décrit un système de détection d'arcs en utilisant deux méthodes différentes, lesquelles sont comparées au niveau des performances de détection. Une méthode de localisation est également décrite et évaluée sur la base de configurations réelles. Enfin, une description du démonstrateur opérationnel développé pour réaliser cette détection et localisation est présentée

Robust sparse representation for adaptive sensing of turbulent phenomena

Special Issue on Compressive Sensing and Robust TransformsInternational audienceIn this study, the authors propose a method for turbulence characterisation by using sparse representation of a channel's impulse response. They consider the case of moving vortices created naturally or artificially that do not conserve their physical properties when observed at two distinct positions in space. The existing amplitude-based techniques fail to provide an accurate representation when the physical properties of the dynamic turbulence are altered. A two stages approach is proposed in this study. The first one deals with the design of robust waveforms for sensing of turbulent phenomena. The second stage consists of sparsely representing the decomposition of the turbulence's impulse response, based on a physically driven decomposition basis. The tests conducted in a reduced scale experimental facility show, on real data, the efficiency of the turbulence tracking. They compare several types of signals and show that the wideband signals are best suited for the application, achieving a high resolution combined with excellent results in terms of robustness

OPTIMIZING LARGE COMBINATIONAL NETWORKS FOR K-LUT BASED FPGA MAPPING

Optimizing by partitioning is a central problem in VLSI design automation, addressing circuit’s manufacturability. Circuit partitioning has multiple applications in VLSI design. One of the most common is that of dividing combinational circuits (usually large ones) that will not fit on a single package among a number of packages. Partitioning is of practical importance for k-LUT based FPGA circuit implementation. In this work is presented multilevel a multi-resource partitioning algorithm for partitioning large combinational circuits in order to efficiently use existing and commercially available FPGAs packagestwo-way partitioning, multi-way partitioning, recursive partitioning, flat partitioning, critical path, cutting cones, bottom-up clusters, top-down min-cut

Adaptive Waveforms for Flow Velocity Estimation Using Acoustic Signals

International audienceIn this paper, we introduce a general framework for waveform design and signal processing, dedicated to the study of turbulent flow phenomena. In a bi-static configuration, by transmitting a specific waveform with a predefined instantaneous frequency law (IFL), within the bounds of the Kolmogorov spectrum, the turbulent media will modify the IFL at the receiving side. We propose a new methodology to estimate this change and to exploit it for velocity estimation using acoustic signals. In this way, the amplitude based velocity estimation techniques can be substituted by non stationary time - frequency signal processing. This technique proves to be more robust in terms of interferences and can provide a more detailed representation of any turbulent environment

Electricité de France's study of the acoustic scintillation flow meter results in expanding its range and sensitivity

International audienceElectricité de France's "Direction Technique Générale" (DTG) branch launched a three-year PhD thesis in order to study the Acoustic Scintillation Flow Meter (ASFM) developed by ASL AQFlow. The study was done in a partnership between EDF DTG (owner of one ASFM system since 2006), Hydro Québec (owner of two ASFM systems) and the manufacturer ASL AQFLow. The partnership aimed at sharing information about the mode of operation and components of the ASFM, as well as sharing the results of the research and development and on-site testing, in order to review the concept of the ASFM and, if feasible, to extend its application beyond its present range. Scientific support was provided by Gipsa-lab, a research laboratory within the Polytechnic Institute of Grenoble (INPG), a major player in the international signal processing community, and the R&D division of EDF located in Chatou, Greater Paris area. In the first two years of the PhD study five major measurement campaigns were performed in France and abroad. In addition, a reduced scale test facility was set up at Gipsa-lab. The main tasks for the PhD candidate were: to review the operational limits for the ASFM, to investigate the impact of various interferences on the discharge measurement, to get a better understanding of the velocity computation algorithm, to develop a method to filter out the scintillation frame vibrations, and to improve the algorithm, if feasible. It is expected that this study may provide the basis for the next generation of acoustic scintillation flow meters

Using wide band signals for obstacle path correction in acoustic scintillation flow meters

International audienceThis paper deals with the challenges of water flow measurement in hydroelectric plants using acoustic scintillation. One of the drawbacks of ultrasonic signal propagation through water is that measurements require relatively clean water conditions. In water with significant amount of impurities, the level of transmitted signals may not be sufficient for an accurate flow measurement. In terms of signal processing, the effect of impurities is represented by a random loss or fading of received signals. In order to improve the measurement, the wide band signals can be used in order to improve the quality factor of the signals by adaptive filtering using a static mode reference. Results show that, in real configurations, the interference due to the obstacles can be reduced

Multi-Lag Phase Space Representations for Transient Signals Characterization

International audienceTransient signals are very difficult to characterize due to their short duration and their wide frequency content. Various methods such as spectrogram and wavelet decomposition have already been extensively used in the literature to detect them, but show limits when it comes to near similar transients discrimination. In this paper, we propose the multi-lag phase space analysis as a way to characterize them. This data-driven method enables the comparison between features extracted from two different signals. In an example, we compare the multi-lag phase space representations of three similar transients and show that common features can be found to discriminate them. Finally the results are compared with a wavelet decomposition

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

The adaptive time-frequency distribution using the fractional fourier transform

Dans cet article nous allons présenter une nouvelle méthode temps-fréquence pour la reduction des terms d'interférence. On va considérer le cas des signaux multi-composants, pour lequel l'élimination des termes d'interférence est difficile à résoudre. Pour extraire les composants utiles, nous proposons une technique basée sur le concept de décomposition atomique. Nous définissons une structure algorithmique pyramidale, en envisageant deux buts: l'amélioration des performances du processus d'estimation et la réduction de la complexité. On met en évidence les avantages de cette méthode, en ce qui concerne l'estimation du taux de modulation linéaire et la complexité

The reaction of some winter wheat variety at cultivation in the conservative system in the Transylvanian Plain area

Introduction: In Europe between wheat cultivators countries, Romania ranks fifth with an area of 2.07 million hectares with a production of 7.45 million tonnes and production obtained is just 3601 kg /ha (www.ager.press.ro).Aims: Through the experience realised at ARDS Turda we follow the behavior of native varieties grȃu autumn, compared È‹n varieties of foreign origin, to make recommendations on their pretability to different systems of culture and levels of fertilization.Materials and Method: The experiment realized at the ARDS Turda, includes two ways to work the soil, a classic conventional system (with autumn ploughing, land preparation, sowing and fertilized) in parallel with the conservative ("no-tillage†with stubble crop directly into the preemergent plant). Experimental factors: A - soil tillage system; B - winter wheat variety; C - fertilization.Results: Of the eight winter wheat varieties, in the experiment is remarkable the variety Capo    that registered highest values of the gluten content at the level of fertilization c2, c3 and c4 at cultivation in both work systems (classic and “no tillageâ€). At most varieties, the highest protein content is at the c2 level of fertilization, except Capo and Exotic that react the best at c3 level of fertilization, in the system "no tillage". Conclusion: The winter wheat  indigenous Andrada, Dumbrava, Arieșan and line T-29-04 and cultivar Renan (Limagrain) reacts most favorable in  gluten content at level of  fertilization c2 (at sowing 250 kg/ ha NPK 20: 20: 0 + resumption spring vegetation È‹n 214 kg/ ha ammonium nitrate).The productions obtained at all varieties wheat,  is not existlarge quantitative differences (200-700 kg/ha differences), but  variety Apache, Exotic, Ariesan and Dumbrava had reached over 7,400 kg / ha. Acknowledgments: This work was supported by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS - UEFISCDI, project number PN-II-RU-TE-2014-4-0884.  References*** www.ager.press.roÂ