Streaming Binary Sketching based on Subspace Tracking and Diagonal Uniformization

In this paper, we address the problem of learning compact similarity-preserving embeddings for massive high-dimensional streams of data in order to perform efficient similarity search. We present a new online method for computing binary compressed representations -sketches- of high-dimensional real feature vectors. Given an expected code length $c$ and high-dimensional input data points, our algorithm provides a $c$-bits binary code for preserving the distance between the points from the original high-dimensional space. Our algorithm does not require neither the storage of the whole dataset nor a chunk, thus it is fully adaptable to the streaming setting. It also provides low time complexity and convergence guarantees. We demonstrate the quality of our binary sketches through experiments on real data for the nearest neighbors search task in the online setting

Crâniométrie chez le chien : étude comparée de spécimens recueillis dans des cavités pyrénéennes (Fouilles André Clot), et des chiens de races connues du Muséum national d'histoire naturelle (Collection Francis Petter)

Crâniométrie chez le chien : étude comparée de spécimens recueillis dans des cavités pyrénéennes (Fouilles André Clot), et des chiens de races connues du Muséum national d'histoire naturelle (Collection Francis Petter

Interlaced spin grating for optical wave filtering

Interlaced Spin Grating is a scheme for the preparation of spectro-spatial periodic absorption gratings in a inhomogeneously broadened absorption profile. It relies on the optical pumping of atoms in a nearby long-lived ground state sublevel. The scheme takes advantage of the sublevel proximity to build large contrast gratings with unlimited bandwidth and preserved average optical depth. It is particularly suited to Tm-doped crystals in the context of classical and quantum signal processing. In this paper, we study the optical pumping dynamics at play in an Interlaced Spin Grating and describe the corresponding absorption profile shape in an optically thick atomic ensemble. We show that, in Tm:YAG, the diffraction efficiency of such a grating can reach 18.3% in the small angle, and 11.6% in the large angle configuration when the excitation is made of simple pulse pairs, considerably outperforming conventional gratings.Comment: 11 pages, 13 figures in Physical Review A, 201

Estimation method for evaluating the wave-induced flicker level emitted by a tidal energy farm

International audienceThe inherently fluctuating nature of sea waves can be reflected to a significant extent in the power output of tidal turbines. However, these fluctuations can give rise to power quality issues such as flicker. Hence, it is important to assess the impact which tidal farms may have on their local network before such power plants are allowed to connect to the grid. This paper analyses under which sea-state and grid conditions a 30 MW rated tidal farm breaches the grid code requirements in terms of short-term flicker level. Then, it describes a simplified method for estimating the flicker level by means of an equivalent sinusoidally-modulated voltage profile

Static and Dynamic Thermo Mechanical Characterization of a Bio-Compatible Shape Memory Polymer

International audienceShape memory polymers encounter a growing interest over the past ten years particularly because their eventual bio-compatibility leads to many bio-medical applications. They also present many benefits for the design of micro-adaptive systems for deployment or controlled damping materials. Indeed, the SMPs are polymeric smart materials which have the remarkable ability to recover their primary shape from a temporary one when submitted to an external stimulus. The present study deals with the synthesis and the thermo-mechanical characterization of a thermally-actuated SMP. The polymer considered hereafter is a chemically cross-linked thermoset. It is synthesized via photo polymerization (UV curing) of the monomer tert-butyl acrylate (tBA) with the crosslinking agent poly(ethylene glycol) dimethacrylate (PEGDMA) and the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (DMPA). A mechanical characterization has been performed using three kinds of tests: quasi-static tensile tests, tensile dynamic mechanical analysis (DMA) and modal tests. The Young's modulus and the Poisson ratio are determined at ambient temperature using the first technique. The DMA is used to determine the evolution of viscoelastic properties as a function of the temperature and the frequency under harmonic loading. The modal analysis is employed to identify the viscoelastic properties of the material at higher frequency. A comparison of the results obtained by these three experimental methods highlights their complementarity

Reemergence of Dengue Virus Type 4, French Antilles and French Guiana, 2004–2005

After 10 years of absence, dengue virus type 4 (DENV-4) has recently reemerged in Martinique, Guadeloupe, and French Guiana. Phylogenetic analyses of strains isolated from 2004 to 2005 showed that they belong to DENV-4 genotype II, but to a different cluster than strains isolated from 1993 to 1995

Rate equation reformulation including coherent excitation: application to periodic protocols based on spectral hole-burning

International audienceA large number of signal-processing protocols are based on recording a spectral pattern via spectral hole-burning in an inhomogeneously broadened absorption profile. We present a simulation method specifically designed for periodic excitation sequences leading to the creation of a spectral pattern. This method is applicable to any multi-level atomic structure. The atomic variables' coherent dynamics are solved for a single temporal excitation step. The result is expressed as an equivalent population transfer rate. This way, the whole sequence is described as a matrix product and the steady state of the system under periodic excitation is easily derived. The propagation through the atomic medium is fully decoupled from the temporal evolution. We apply this method to the engraving of a spectral grating in a large-absorption Tm:YAG sample for wideband spectral analysis

Wave-induced flicker level emitted by a tidal farm

International audienceThe inherently fluctuating nature of sea waves can be reflected to a significant extent in the power output of tidal turbines. However, these fluctuations can give rise to power quality issues such as flicker. Hence, it is important to assess the impact which tidal farms may have on their local network before such power plants are allowed to connect to the grid. This paper describes the influence of the wave climate on the short-term flicker level induced by a tidal farm on the point of common coupling. It analyses also under which conditions the tidal farm breaches the grid code requirements in terms of short-term flicker level