Time-domain numerical simulations of multiple scattering to extract elastic effective wavenumbers

Elastic wave propagation is studied in a heterogeneous 2-D medium consisting of an elastic matrix containing randomly distributed circular elastic inclusions. The aim of this study is to determine the effective wavenumbers when the incident wavelength is similar to the radius of the inclusions. A purely numerical methodology is presented, with which the limitations usually associated with low scatterer concentrations can be avoided. The elastodynamic equations are integrated by a fourth-order time-domain numerical scheme. An immersed interface method is used to accurately discretize the interfaces on a Cartesian grid. The effective field is extracted from the simulated data, and signal-processing tools are used to obtain the complex effective wavenumbers. The numerical reference solution thus-obtained can be used to check the validity of multiple scattering analytical models. The method is applied to the case of concrete. A parametric study is performed on longitudinal and transverse incident plane waves at various scatterers concentrations. The phase velocities and attenuations determined numerically are compared with predictions obtained with multiple scattering models, such as the Independent Scattering Approximation model, the Waterman-Truell model, and the more recent Conoir-Norris model.Comment: Waves in Random and Complex Media (2012) XX

Trait‐based analysis of subpolar North Atlantic phytoplankton and plastidic ciliate communities using automated flow cytometer

Plankton are an extremely diverse and polyphyletic group, exhibiting a large range in morphological and physiological traits. Here, we apply automated optical techniques, provided by the pulse‐shape recording automated flow cytometer—CytoSense—to investigate trait variability of phytoplankton and plastidic ciliates in Arctic and Atlantic waters of the subpolar North Atlantic. We used the bio‐optical descriptors derived from the CytoSense (light scattering [forward and sideward] and fluorescence [red, yellow/green and orange from chlorophyll a, degraded pigments, and phycobiliproteins, respectively]) and translated them into functional traits to demonstrate ecological trait variability along an environmental gradient. Cell size was the master trait varying in this study, with large photosynthetic microplankton (> 20 μm in cell diameter), including diatoms as single cells and chains, as well as plastidic ciliates found in Arctic waters, while small‐sized phytoplankton groups, such as the picoeukaryotes (< 4 μm) and the cyanobacteria Synechococcus were dominant in Atlantic waters. Morphological traits, such as chain/colony formation and structural complexity (i.e., cellular processes, setae, and internal vacuoles), appear to favor buoyancy in highly illuminated and stratified Arctic waters. In Atlantic waters, small cell size and spherical cell shape, in addition to photo‐physiological traits, such as high internal pigmentation, offer chromatic adaptation for survival in the low nutrient and dynamic mixing waters of the Atlantic Ocean. The use of automated techniques that quantify ecological traits holds exciting new opportunities to unravel linkages between the structure and function of plankton communities and marine ecosystems

1 MCI – MULTILANGUAGE DISTRIBUTED CO-SIMULATION TOOL

Nowadays the design of complex systems requires the cooperation of several teams belonging to different cultures and using different languages. It is necessary to dispose of new design and verification methods to handle multilanguage approaches. This paper presents a multilanguage co-simulation tool that allows cosimulation of multilanguage specifications for complex systems

Structural and electrical properties of K3Li2Nb5O15 thin film grown by pulsed laser deposition

International audiencePotassium lithium niobate K3Li2Nb5O15 (KLN) with tetragonal tungsten bronze-type structure (TIT) thin film was successfully deposited on MgO substrate by pulsed laser ablation method. The substrate was coated by a perovskite conductive layer of La0.5Sr0.5CoO3. X-ray diffraction revealed (001) orientation with low mosaicity. The oriented film had smooth and droplets-free surface as evidenced by reflection high electron energy diffraction and atomic force microscopy. Using Pt top electrode, dielectric measurements indicated stable dielectric permittivity of about 400 up to 10(5) Hz. A dielectric relaxation was also observed. Moreover, the capacitance voltage measurements of the obtained (001)KLN film show ferroelectric behavior. Our results provide useful insights into the growth of tetragonal tungsten and other complex materials. These results will be useful for the growth and integration of epitaxial TTB thin films on perovskite and Si substrates. (C) 2017 Elsevier Ltd. All rights reserved

Bipolar resistive switching and substrate effect in GdK2Nb5O15 epitaxial thin films with tetragonal tungsten bronze type structure

International audienceFerroelectric compound GdK2Nb5O15 with tetragonal tungsten bronze type structure thin films were grown by pulsed laser deposition on (001) SrRuO3/SrTiO3 and (001) SrRuO3/LSCO/MgO substrates respectively, in the same experimental conditions. Structural properties were investigated using X-ray diffraction in different modes theta-2 theta diffraction shows a single crystalline SRO and GKN phases, with c-axis perpendicular to the substrate. Phi-scans show for both SRO and GKN an epitaxial cube-on-cube growth. Reciprocal space mapping (RSM) was performed on GKN to determine the in-plane lattice parameters, and showed that GKN grown on MgO is more constrained comparing to STO. Room temperature electrical properties were investigated using platinum (Pt) top electrodes. Results show that GKN thin films deposited on MgO and STO substrates are resistively switchable. It was found that the nature of the substrate affects strongly the resistance ratio: GKN on SRO/LSCO/MgO showed a large hysteresis comparing to GKN on SRO/STO. Resistance switching in GKN is attributed to the oxygen vacancies migration which can be controlled by the substrate or the frequency sweep. (C) 2016 Elsevier Ltd. All rights reserved

Oxygen-deficient GdK

The ferroelectric compound GdK2Nb5O15 (GKN) thin film with tetragonal-tungsten-bronze–type structure was grown by pulsed-laser deposition on (001)SrRuO3/La0.5Sr0.5CoO3/MgO substrate. Using X-ray diffraction analysis we demonstrate that the phase transition temperature in the GKN thin film was shifted to high temperatures due to substrate-induced stress. Impedance spectroscopy investigations show Maxwell-Wagner–type conduction at low frequencies, which leads to resistive switching. Oxygen vacancies and temperature effects were studied to highlight the stability of the resistive switching behavior in the GKN thin film

Oxygen-deficient GdK2Nb5O15 ferroelectric epitaxial thin film

International audienceThe ferroelectric compound GdK2Nb5O15 (GKN) thin film with tetragonal-tungstenbronze-type structure was grown by pulsed-laser deposition on (001) SrRuO3/La0.5Sr0.5CoO3/MgO substrate. Using X-ray diffraction analysis we demonstrate that the phase transition temperature in the GKN thin film was shifted to high temperatures due to substrate-induced stress. Impedance spectroscopy investigations show Maxwell-Wagner-type conduction at low frequencies, which leads to resistive switching. Oxygen vacancies and temperature effects were studied to highlight the stability of the resistive switching behavior in the GKN thin film. Copyright (C) EPLA, 201

Studies on <i>gtf</i>, a glucosyltransferase gene in the genome of <i>Pediococcus parvulus</i> and <i>Oenococcus oeni</i>, two bacterial species commonly found in wine

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Changes in red wine soluble polysaccharide composition induced by malolactic fermentation

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