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International audience; Performative speech synthesis is a new avenue for expressive speech and singing analysis andsynthesis. At the confluence between new interfaces for musical expression, voice signal processingand acoustic phonetics, two vocal instruments are presented. Cantor Digitalis, a formant synthesizerusing a spectral glottal model, is controlled using bimanual gestures on a graphic tablet. Voks is basedon sampling and vocoding. It is controlled by bimanual gestures (graphic tablet or theremin) andbiphasic syllabic sequencing. Prosodic units and their organization for vocal instruments are discussedalong three lines: chironomic stylization of intonation and vocal effort, biphasic syllabic rhythmcontrol. Musical, pedagogical and clinical applications of this new organology of voice are discussed.; La synthèse vocale performative offre une nouvelle approche pour l’analyse et la synthèse de la paroleexpressive et du chant. Deux instruments vocaux, à la confluence entre nouvelles interfaces pourl’expression musicale, traitement du signal vocal et phonétique acoustique, sont présentés. CantorDigitalis est un synthétiseur à formants muni d’un modèle spectral de la source glottique, piloté pardes gestes bimanuels sur une surface tactile et un stylet. Voks est un vocodeur piloté par des gestesbimanuels, sur une surface tactile et un stylet, ou par un thérémine, augmenté d’un contrôle biphasiquedu séquencement syllabique. Les unités prosodiques, leur organisation et leur contrôle pour laconstruction des instruments vocaux sont discutés suivant trois lignes : la stylisation chironomique del’intonation et de l’effort vocal, le contrôle biphasique du rythme syllabique. La conclusion évoqueles applications musicales, pédagogiques, voire cliniques de cette nouvelle organologie de la voix.

International audience; Peregrine soliton (PS) is widely regarded as a prototype nonlinear structure capturing properties of rogue waves that emerge in the nonlinear propagation of unidirectional wave trains. As an exact breather solution of the one-dimensional focusing nonlinear Schrödinger equation with nonzero boundary conditions, the PS can be viewed as a soliton on finite background, i.e., nonlinear superposition of a soliton and a monochromatic wave. A recent mathematical work showed that both nonzero boundary conditions and solitonic content are not pre-requisites for the PS occurrence. Instead, it has been demonstrated that PS can emerge locally, as an asymptotic structure arising from the propagation of an arbitrary large decaying pulse, independently of its solitonic content. This mathematical discovery has changed the widely accepted paradigm of the solitonic nature of rogue waves by enabling the PS to emerge from a partially radiative or even completely solitonless initial data. In this work, we realize the mathematically predicted universal mechanism of the local PS emergence in a water tank experiment with a particular aim to control the point of the PS occurrence in space-time by imposing an appropriately chosen initial chirp. By employing the inverse scattering transform for the synthesis of the initial data, we are able to engineer a localized wave packet with a prescribed solitonic and radiative content. This enabled us to control the position of the emergence of the rogue wave by adjusting the inverse scattering spectrum. The proposed method of the nonlinear spectral engineering is found to be robust to higher-order nonlinear effects inevitable in realistic wave propagation conditions.

The concept of Nonlinear dispersion relation (NDR) is used in various fields of Physics (nonlinear optics, hydrodynamics, hydroelasticity, mechanics, quantum optics, plasma physics,...) to characterize fundamental phenomena induced by nonlinearity such as wave frequency shift or turbulence. Nonlinear random waves described by the onedimensional nonlinear Schrodinger equation (1DNLSE) exhibit a remarkable form of turbulence called "integrable turbulence" where solitons play a key role. Surprisingly, little attention has been paid to the NDR of such universal wave systems up to a very recent theoretical study. Here, by using an original strategy, we report the accurate measurement of NDR of the slowly varying envelop of the waves in one-dimensional deep water waves experiments. We characterize precisely the frequency shift and the broadening of the NDR, which interestingly reveals the presence of solitons and of high order effects. Our results highlight the relevance of the NDR in the context of integrable turbulence., 12 pages, 9 figures

International audience; This research aims to build a prosodic boundary prediction model for improving the naturalness of Vietnamese speech synthesis. This model can be used directly to predict prosodic boundaries in the synthesis phase of the statistical parametric or end-to-end speech systems. Beside conventional features related to Part-Of-Speech (POS), this paper proposes two efficient features to predict prosodic boundaries: syntactic blocks and syntactic links, based on a thorough analysis of a Vietnamese dataset. Syntactic blocks are syntactic phrases whose sizes are bounded in their constituent syntactic tree. A syntactic link of two adjacent words is calculated based on the distance between them in the syntax tree. The experimental results show that the two proposed predictors improve the quality of the boundary prediction model using a decision tree classification algorithm, about 36.4% (F1 score) higher than the model with only POS features. The final boundary prediction model with POS, syntactic block, and syntactic link features using the LightGBM algorithm gives the best F1-score results at 87.0% in test data. The proposed model helps the TTS systems, developed by either HMM-based, DNN-based, or End-to-end speech synthesis techniques, improve about 0.3 MOS points (i.e. 6 to 10%) compared to the ones without the proposed model.

International audience; Speech glottal flow has been predominantly described in the time-domain in past decades, the Liljencrants-Fant (LF) model being the most widely used in speech analysis and synthesis, despite its computational complexity. The causal/ anti-causal linear model (LF CALM) was later introduced as a digital filter implementation of LF, a mixed-phase spectral model including both anti-causal and causal filters to model the vocal-fold open and closed phases, respectively. To further simplify computation, a causal linear model (LF LM) describes the glottal flow with a fully causal set of filters. After expressing these three models under a single analytic formulation, we assessed here their perceptual consistency, when driven by a single parameter R d related to voice quality. All possible paired combinations of signals generated using six R d levels for each model were presented to subjects who were asked whether the two signals in each pair differed. Model pairs LF LM-LF CALM were judged similar when sharing the same R d value, and LF was considered the same as LF LM and LF CALM given a consistent shift in R d. Overall, the similarity between these models encourages the use of the simpler and more computationally efficient models LF CALM and LF LM in speech synthesis applications.

International audience; In strongly anisotropic materials the orientation-dependent fracture surface energy is a non-convex function of the crack angle. In this context, the classical Griffith model becomes ill-posed and requires a regularization. We revisit the crack kinking problem in materials with strongly anisotropic surface energies by using a variational phase-field model. The model includes in the energy functional a quadratic term on the second gradient of the phase-field. This term has a regularizing effect, energetically penalizing the crack curvature. We provide analytical formulas for the dependence of the surface energy on the crack direction and develop an open-source finite-element solver for the higher-order phase-field problem. Quantitative numerical experiments for the crack kinking problem show that the crack kinking directions observed in our phase-field simulations are in close agreement with the generalized maximum energy release rate criterion. Finally, we revisit a thermal quenching experiment in the case of slabs with strongly anisotropic surface energies. We show that the anisotropy can strongly affect the observed crack patterns, either by stabilizing straight cracks or by inducing zigzag crack patterns. In the case of zigzag cracks, we observe that crack kinking is always associated with an unstable propagation of a finite length add-crack in a single time-step.

International audience; Les équations macroscopiques de bilan des interfaces fluides ont été établies en considérant deux échelles de longueur et moyennant quelques approximations, telles que la conservation du vecteur vitesse mixte et du gradient parallèle à la traversée de la zone interfaciale. Nous généralisons cette méthode au cas des quadri interfaces en présence de champs électromagnétiques. Le passage à l'espace-temps i, ii est en effet un moyen d'obtenir une présentation homogène des bilans 1 .

International audience; Soliton gases represent large random soliton ensembles in physical systems that display integrable dynamics at the leading order. Despite significant theoretical developments and observational evidence of ubiquity of soliton gases in fluids and optical media their controlled experimental realization has been missing. We report the first controlled synthesis of a dense soliton gas in deep-water surface gravity waves using the tools of nonlinear spectral theory (inverse scattering transform (IST)) for the one-dimensional focusing nonlinear Schrödinger equation. The soliton gas is experimentally generated in a one-dimensional water tank where we demonstrate that we can control and measure the density of states, i. e. the probability density function parametrizing the soliton gas in the IST spectral phase space. Nonlinear spectral analysis of the generated hydrodynamic soliton gas reveals that the density of states slowly changes under the influence of perturbative higher-order effects that break the integrability of the wave dynamics.

International audience; We present an experiment run in France and Korea along the lines of a pilot experiment run in China (Taupin, semiotica, https://doi.org/10.1515/sem-2018-0005). In order to find out what are soundscapes in the imaginaries of native digital users of the Z generation, participants had to realize collages in group of two to illustrate their experience when walking through urban sceneries. They were free to clip any image they wanted from a selection of magazines, the same for all groups within each country, and free to add any comment or drawing they wanted to on their collages. Then they had to present their collage to the other participants. The presentations were recorded, transcribed, and analyzed in order to determine the imaginaries that underlie the usage and attitudes. Beyond the analysis, the presentation will explain the theoretical background and the results of the experiments.

This paper discusses the dynamic between digital tools and the actor’s ability to listen. It presents the results of the workshop Voices on Stage: An Approach to Ancient Greek Tragedy in the Digital Era (Athens, 2018) which confronts the actor to different layers of voice (direct, amplified, and synthetic). Through those experiments and their analysis, one will demonstrate how listening to synthetic voices can reinforce the actor’s sensibility to voice, stimulate his/her’s other senses and transform the act of listening into a tactile and visual experience., L'acteur et l'écoute augmentée: tissage sonore de voix autour des Bacchantes d'Euripide En s'appuyant sur une expérience pédagogique basée sur la confrontation des voix nonmédiatisée, amplifiée et synthétisée, lors du workshop Voices On Stage : An Approach to Ancient Greek Tragedy in the Digital Era (Athènes, 2018), cet article propose une réflexion sur la relation entre les technologies digitales et l'écoute de l'acteur. Il s'agit de démontrer que l'écoute de voix de synthèse-souvent mise en opposition aux voix "naturelles" ou "organiques"-peut paradoxalement constituer pour l'acteur une façon de renforcer son rapport sensible à la voix et de stimuler ses sens autrement., O ator e a escuta aumentada: tecido de vozes em As Bacantes de Eurípides Partindo de uma experiência artística e pedagógica baseada no encontro de vozes não midiatizadas, vozes amplificadas e vozes sintetizadas durante o workshop Voices on Stage: An Approach to Ancient Greek Tragedy in the Digital Era (Atenas, 2018), este artigo discute a relação entre as tecnologias digitais e a escuta do ator. O objetivo é demonstrar que as vozes sintetizadas-geralmente consideradas como o extremo oposto das vozes ditas "naturais" e "orgânicas"-pode paradoxalmente reforçar a relação sensível do ator com sua própria voz e estimular outros sentidos, tornando a escuta tátil e visual.

In this paper we investigate dynamic wetting in the curtain coating configuration. The two-phase Navier-Stokes equations are solved by a Volume-of-Fluid method on an adaptive Cartesian mesh. We introduce the Navier boundary condition to regularize the solution at the triple point and remove the implicit numerical slip induced by the cell-centered interface advection. We use a constant contact angle to describe the dynamic contact line. The resolution of the governing equations allows us to predict the substrate velocity at which wetting failure occurs. The model predictions are compared with prior computations and experimental observations., Comment: 13 pages, 11 figures, post-review version, under consideration for publication in "European Physical Journal Special Topics"

A series of benchmarks based on the physical situation of "phase inversion" between two immiscible liquids is presented. These benchmarks aim at progressing toward the direct numerical simulation of two-phase flows. Several CFD codes developed in French laboratories and using either Volume-of-Fluid or Level-Set interface tracking methods are used to provide physical solutions of the benchmarks, convergence studies and code comparisons. Two typical configurations are retained, with integral scale Reynolds numbers of 13.700 and 433.000, respectively. The physics of the problem are probed through macroscopic quantities such as potential and kinetic energies, or enstrophy. In addition, scaling laws for the temporal decay of the kinetic energy are derived to check the physical relevance of the simulations. Finally the droplet size distribution is probed. Additional test problems are also reported to estimate the influence of viscous effects in the vicinity of the interface., 35 pages, 35 figures, third revision submitted to J. Comput. Phys

International audience; This article presents a semi-discrete, multilayer set of equations describing the three-dimensional motion of an incompressible fluid bounded below by topography and above by a moving free-surface. This system is a consistent discretisation of the incompressible Euler equations, valid without assumptions on the slopes of the interfaces. Expressed as a set of conservation laws for each layer, the formulation has a clear physical interpretation and makes a seamless link between the hydrostatic Saint-Venant equations, dispersive Boussinesq-style models and the incompressible Euler equations. The associated numerical scheme, based on an approximate vertical projection and multigrid-accelerated column relaxations, provides accurate and efficient solutions for all regimes. The same model can thus be applied to study metre-scale waves, even beyond breaking, with results closely matching those obtained using small-scale Euler/Navier-Stokes models, and coastal or global scale dispersive waves, with an accuracy and efficiency comparable to extended Boussinesq wave models. The implementation is adaptive, parallel and open source as part of the Basilisk framework and the documented source codes sufficient to reproduce all results and figures are provided.

International audience; We investigate experimentally the different shapes taken by a water drop freezing during its impact on a cold surface. We show that these shapes are formed by a water film that remains on top of the first formed ice layer. The capillary hydrodynamics of this water film dewetting on its own ice, coupled with its vertical solidification, is thus quantitatively characterized, allowing us to understand and predict the formation of the emerging patterns. Finally, this experiment enables us to study the contact angle dynamics, giving deep insight into the wetting of water on ice.

International audience; When a bubble bursts at the surface of a liquid, it creates a jet that may break up and produce jet droplets. This phenomenon has motivated numerous studies due to its multiple applications, from bubbles in a glass of champagne to ocean/atmosphere interactions. We simulate the bursting of a single bubble by direct numerical simulations of the axisymmetric two-phase liquid-gas Navier-Stokes equations. We describe the number, size and velocity of all the ejected droplets, for a wide range of control parameters, defined as non-dimensional numbers, the Laplace number which compares capillary and viscous forces and the Bond number which compares gravity and capillarity. The total vertical momentum of the ejected droplets is shown to follow a simple scaling relationship with a primary dependency on the Laplace number. Through a simple evaporation model, coupled with the dynamics obtained numerically, it is shown that all the jet droplets (up to fourteen) produced by the bursting event must be taken into account as they all contribute to the total amount of evaporated water. A simple scaling relationship is obtained for the total amount of evaporated water as a function of the bubble size and fluid properties. This relationship is a first important step toward building a physics-based model of the ocean-atmosphere water vapour fluxes controlled by bubbles bursting at the surface.

International audience; We study experimentally the early stages of integrable turbulence of unidirectional deep water gravity waves. By generating partially coherent waves in a 148 m long wave flume, we observe the emergence of high-amplitude structures formed by nonlinear focusing, commonly referred to as rogue waves. This work confronts the experiment with two recent results obtained in the framework of the nonlinear Schrödinger equation (NLSE), namely that (i) these structures can be locally fitted by a Peregrine soliton and (ii) their emergence leaves a visible trace on the evolution of statistical parameters such as kurtosis. Although Peregrine solitons have been observed for almost ten years in experiments using a deterministic forcing, we report their first systematic study in hydrodynamics with a random forcing. We show that (i) yields accurate results as long as the wave steepness remains moderate, whereas (ii) is very robust and remains valid beyond the assumption of integrability. Numerical simulations of the NLSE and of the fully nonlinear dynamical equations are also performed to support these results.

A new particle tracking algorithm is derived based on consolidated methods, with the aim of overcoming the current limits encountered with high particle density flows. The proposed method consists of an integration of the relaxation algorithm based on matching probabilities into vision-based features association concepts. Hybridization with PIV pre-analysis is suggested to help with the estimation of parameters. A dual calculation strategy is also developed in order to reduce the amount of spurious vectors. Simulation tests using synthetically generated images are carried out to evaluate the sensitivity of the proposed method to the particle image density, the background noise and the nature of the flow. Three flow configurations with a growing degree of complexity are successively considered: a 2D flow over a moving wall, a steady 2D Lamb–Oseen vortex ring, and a 3D unsteady homogeneous isotropic turbulence. The ability of the new tracking algorithm to provide better matching performances with high reliability than conventional techniques, out of a dense particle image field, is demonstrated.

The time-domain propagation of scalar waves across a periodic row of inclusions is considered in 2D. As the typical wavelength within the background medium is assumed to be much larger than the spacing between inclusions and the row width, the physical configuration considered is in the low-frequency homogenization regime. Furthermore, a high contrast between one of the constitutive moduli of the inclusions and of the background medium is also assumed. So the wavelength within the inclusions is of the order of their typical size, which can further induce local resonances within the microstructure. In Pham et al. (J. Mech. Phys. Solids 106:80–94, 2017), two-scale homogenization techniques and matched-asymptotic expansions have been employed to derive, in the harmonic regime, effective jump conditions on an equivalent interface. This homogenized model is frequency-dependent due to the resonant behavior of the inclusions. In this context, the present article aims at investigating, directly in the time-domain, the scattering of waves by such a periodic row of resonant scatterers. Its effective behavior is first derived in the time-domain and some energy properties of the resulting homogenized model are analyzed. Time-domain numerical simulations are then performed to illustrate the main features of the effective interface model obtained and to assess its relevance in comparison with full-field simulations.

International audience; This paper presents Voks, a new family of digital instruments that allow for real-time control and modification of pre-recorded voice signal samples. An instrument based on Voks is made of Voks itself, the synthesis software and a given set of chironomic (hand-driven) interfaces. Rhythm can be accurately controlled thanks to a new methodology, based on syllabic control points. Timing can also be controlled with other methods, including scrubbing and playback speed variation. Pitch, vocal effort, voice tension, apparent vocal tract size, voicing ratio, aperiodicity ratio of the voice samples can be modified thanks to a real-time high-quality vocoder. Different forms of chironomic control of the vocal parameters are proposed. Pitch is controlled by continuous hand motions using a stylus on a surface (C-Voks) or a theremin (T-Voks). Other interfaces can be used as well. Syllabic rhythm is controlled using a biphasic button. Scrubbing, playback speed and timbre related parameters can be controlled using the theremin, control surfaces or continuous controllers like faders. In addition to realistic imitation of speaking or singing voices, other playing modes yield new interesting sounds. Voks participated in comparative perceptual evaluation of singing synthesis systems. It has been demonstrated in a live musical settings, using different control interfaces. In addition to musical or poetic performances, applications of performative vocal synthesis to language learning and speech reeducation are foreseen.

International audience; We studied experimentally the discharge of a vertical silo filled by spherical glass beads and assisted by injection of air from the top at a constant flow rate, a situation which has practical interest for nuclear safety or air-assisted discharge of hoppers. The measured parameters are the mass flow rate and the pressure along the silo, while the controlled parameters are the size of particles and the flow rate of air. Increasing the air flow rate induces an increase in the granular media flow rate. Using a two-phase continuum model with a frictional rheology to describe particle-particle interactions, we reveal the role played by the air pressure gradient at the orifice. Based on this observation we propose a simple analytical model which predicts the mass flow rate of a granular media discharged from a silo with injection of gas. This model takes into account the coupling with the gas flow as well as the silo geometry, position and size of the orifice.

International audience; This paper describes research done on a new testing device including its laboratory test procedure; namely, a laboratory punching test for cementitious backfill materials that evaluates their excavatability with a pick. Three-dimensional and two-dimensional numerical studies using a finite element method were carried out according to calibrated parameters of the material obtained by triaxial tests. This made it possible to study the behavior of the backfill material under action induced by a tool (a pick) as well as to optimize the geometry of the punching test specimen. This paper provides detailed information and results for the experimental study of this laboratory test. Attention was particularly focused on energy relating to displacement as well as types of ruptures. The behavior of these types of materials was found to be greatly influenced by gravel in the material. Repeatability of the test was also studied. Finally, a method for this punching test of backfill materials is also provided.

The present research attempts to non-destructively characterize mechanical properties, which are representative of the interfacial adhesion and bond line cohesion of adhesively bonded assemblies, using an ultrasonic method. Eight bonded samples made of two aluminium substrates and of an epoxy-based adhesive layer were manufactured: four in which the adhesive is fully cured (100%) and four in which crosslinking is partial (80%). For each level of curing, four different surface treatments were applied to the aluminium substrates before assembling, in order to vary the quality of adhesion. Ultrasonic plane wave transmission coefficients (UPWTC) were either measured in a water tank, or simulated using the well-known stiffness matrix method that micmics the experiments, to produce input data for the inverse problem. This latest consists in the evaluation of the elastic properties of either the adhesive bond or the interphases between both substrates and the adhesive layer. If the interphases are of nominal quality, the values of the inferred properties of the adhesive bond match those previously measured on individual epoxy samples, whether the epoxy is fully or partially cured. However, when interphases are not of nominal quality level, the optimized bond moduli reveal an apparent anisotropy, although the epoxy layer is known to be isotropic. This apparent anisotropy is explained by an analytical rule of mixture, thus giving confidence in the proposed ultrasonic technique, which is then suggested as a potential way to detect weaknesses of interphases. Finally, the optimization of the interphases elastic properties is carried out. The measured normal and shear stiffnesses are shown to decrease as the interphases get degraded. All ultrasonically-measured parameters (apparent anisotropy of the bond and interfacial stiffnesses) vary monotonically with the bonds strength, which was measured via mechanical tests. The proposed UPWTC method was shown to have a strong potential to distinguish between adhesive and cohesive weaknesses of bonded joints, and to estimate corresponding mechanical properties.

International audience; In November 2014, at the annual meeting of the research group “Fundamental and Applied Microgravity” held in Carqueiranne, France, I was asked to speak on Bernard Zappoli and his accomplishments. The following is an edited transcription of the speech delivered in his honor following his recent retirement as the Head of The Physical Science Programme at the French Space Agency (CNES). After an introduction outlining his human qualities and retirement as engineer emeritus, his career is summarized. It then details the scientific activities he has undertaken during different periods of his career at several universities, the European Society of Propulsion (“Société européenne de propulsion”, SEP), and the CNES. Special attention is devoted to the research groups at the CNES/CNRS that we initiated and the management of which I had been sharing with him for several years. Allusion is made to his recent and new retiree activities.

Nitrogen oxides, which refer specifically to NOx (NO and NO2), are the major pollutants in the atmosphere from industries (mobile or stationary sources), which lead to acid rain and photochemical smog, and have been shown to be detrimental to human health and the environment. Automobiles and other mobile sources contribute to about 50% of the NOx that is emitted in the atmosphere, and nitrogen monoxide (NO) is the major portion of it This chapter reviews recent progress and challenges in the use of plasma catalysis for NOx removal.

We report water wave experiments performed in a long tank where we consider the evolution of nonlinear deep-water surface gravity waves with the envelope in the form of a large-scale rectangular barrier. Our experiments reveal that, for a range of initial parameters, the nonlinear wave packet is not disintegrated by the Benjamin-Feir instability but exhibits a specific, strongly nonlinear modulation, which propagates from the edges of the wavepacket towards the center with finite speed. Using numerical tools of nonlinear spectral analysis of experimental data we identify the observed envelope wave structures with focusing dispersive dam break flows, a peculiar type of dispersive shock waves recently described in the framework of the semi-classical limit of the 1D focusing nonlinear Schrodinger equation (1D-NLSE). Our experimental results are shown to be in a good quantitative agreement with the predictions of the semi-classical 1D-NLSE theory. This is the first observation of the persisting dispersive shock wave dynamics in a modulationally unstable water wave system., 7 figures

Stenosis, defined by a partial or full obstruction of the arteries, is a frequent anomaly in the cardiovascular system. The pressure drop across a stenosis indicates the severity of the pathology. There is currently no non-invasive method to obtain this pressure drop. In this communication, we use four different blood flow models to compute the pressure in an idealized geometry of stenosis: the steady RNSP model, the Multi-Ring model, the 1D model, and algebraic models. We compare these models on a test case under a steady flow. We then developed a gradient-based parameter estimation method to compare the complex models (1D and Multi-Ring) with algebraic formulas. We used the parameter estimation to evaluate the influence of the geometry, wall elasticity and flow parameter on the empirical coefficients of the algebraic formulas.

International audience; This letter proposes a new statistical model of thunder. The tortuous geometry of the emitting return stroke is randomly generated to fit observations of negative cloud‐to‐ground discharges. Pressure waves are initialized by radiation‐hydrodynamics simulations and linearly propagated into an isothermal atmosphere incorporating standardized sound absorption. The thunder pressure frequency signal is defined as the product of the input pressure governed by a deposited energy with the stochastic frequency response of the elongated discharge. We find the low‐frequency content of thunder is mostly due to stroke elongation originating from tortuosity. Acoustic energy per stroke length and spectrum slope are statistically compared to measurements, with good agreement found. We show both a near‐ and far‐field regime of the acoustical energy over distance described by two different power laws. The correlation found between the lightning energy and the acoustic energy paves the way for using thunder measurement to estimate deposited energy.

International audience; The French ECHO project studies the use of voice in the recent history of theater. It is a multidisciplinary project which combines the efforts of historians, theater scientists, and acousticians. In the scope of this project an audiovisual simulation was created which combines auralizations with visualizations of former Théâtre de l'Athénée configurations issue from a series of renovations, enabling researchers to realistically perceive theater performances in foregone rooms. Simulations include the room, 2 actors on stage, and an audience. To achieve these simulation, architectural plans were studied from archives providing various details of the different theater configurations, from which the corresponding visual and room acoustic geometrical acoustics (GA) models were created. The resulting simulations allow for 360°audio-visual presentations at various positions in the theater using commercial standard hardware.

International audience; This paper presents the details related to the creation of a public database of anechoic audio and 3D-video recordings of several small music ensemble performances. Musical extracts range from baroque to jazz music. This work aims at extending the already available public databases of anechoic stimuli, providing the community with flexible audiovisual content for virtual acoustic simulations. For each piece of music, musicians were first close-mic recorded together to provide an audio performance reference. This recording was followed by individual instrument retake recordings, while listening to the reference recording, to achieve the best audio separation between instruments. In parallel, 3D-video content was recorded for each musician, employing a multiple Kinect 2 RGB-Depth sensors system, allowing for the generation and easy manipulation of 3D point-clouds. Details of the choice of musical pieces, recording procedure, and technical details on the system architecture including post-processing treatments to render the stimuli in immersive audiovisual environments are provided.

International audience; Dynamic changes of the Head-Related Transfer Function renderings as a function of head movement have been shown to be an important cue in sound localization. To investigate the cognitive process of dynamic sound localization, quantification of the characteristics of head movements is needed. In this study, trajectories of head rotation in a sound localization task were measured and analyzed. Listeners were asked to orient themselves towards the direction of active sound source via localization, being one of five loudspeakers located at 30 • intervals in the horizontal plane. A 1 s pink noise burst stimulus was emitted from different speakers in random order. The range of expected head rotations (EHR) for a given stimulus were, therefore, from 30 • to 120 •. Head orientation was measured with a motion capture system (yaw, pitch, and roll). Analysis examined angular velocity, overshoot, and reaction time (RT). Results show that angular velocity increased as EHR increased. No relationship between overshoot and EHR was observed. RT was almost constant (≈260 ms) regardless of EHR. This may suggest that dynamic sound localization studies could be difficult for a short stimulus with duration less than 260 ms.

International audience; Une musique apaisante au quotidien L'expression des réponses de stress associées à des stimuli visuels et soudains est diminuée grâce l'utilisation de la musique. Ainsi, il est recommandé de l'utiliser pour diminuer l'impact négatif des situations rencontrées au quotidien (découverte d'un nouvel environnement lors d'une ballade, d'un changement d'écurie ou encore lors d'une journée de concours sur un nouveau terrain). En outre, les premières analyses suggèrent une contribution des paramètres acoustiques et musicaux mais aussi de l'atténuation de l'environnement sonore à l'effet apaisant observé. Si l'on projette ces résultats sur le terrain, la majorité des accidents étant dus à l'expression des réponses de peur et de fuite, ces résultats montrent que l'utilisation de la musique comme outil de gestion au quotidien permet de sécuriser les interactions humains/chevaux en limitant le stress des individus vis-à-vis de leur environnement visuel au moins jusqu'à 10 jours consécutifs d'utilisation. Et même si son utilisation permet une diminution de l'expression des comportements de stress, celle-ci n'interfère pas avec la perception et la réponse aux bruits de l'environnement. Une utilisation quotidienne est recommandée sans risque de diminution de l'efficacité Pour déterminer l'impact de la musique sur l'état de stress des chevaux et étudier un potentiel phénomène d'habituation ou de sensibilisation, nous avons comparé 3 groupes de 12 chevaux qui ont été soumis de manière répétée à cette même situation de stress mais chacun dans une seule des 3 conditions expérimentales (musique, sans musique et bruit rose, N = 36). La situation de stress que nous avons choisie est celle d'un trajet en main le long d'un parcours ponctué de stimuli potentiellement stressants (5 stimuli visuels et/ou 5 stimuli soudains et 5 stimuli auditifs). De cette manière, le groupe de chevaux testés en condition « sans musique » permet de vérifier le caractère stressant du parcours en main et d'observer si une habituation à ce stress a lieu. Le groupe en condition « musique » nous permet d'évaluer l'impact de la musique sur l'état de stress des chevaux et d'observer si un phénomène d'habituation et/ou de sensibilisation à la musique intervient ou non. Enfin, la condition « bruit » est nécessaire pour s'assurer que les différences que l'on pourrait observer en condition « musique » sont dues aux caractéristiques acoustiques et musicales de la bande son et non pas à la simple stimulation auditive impliquant notamment une certaine atténuation de l'environnement sonore du cheval. Les réponses apportées par cette étude permettent de recommander l'utilisation quotidienne de la musique les jours de travail pour apaiser les chevaux (avant ou après) sans risque de diminution de son efficacité.

This paper experimentally documents the transition from the “closed-tip” flame configuration to the “open-tip” one that a laminar axisymmetric coflow ethylene/air non-premixed flame experiences with increasing the fuel flow rate at the smoke point in terms of soot temperature and volume fraction distributions. To this end, the two-dimensional soot temperature and volume fraction fields are measured by the two-color Modulated Absorption/Emission (2C-MAE) technique. The MAE setup has been specifically extended to a third spectral range centered at a lower wavelength (405 nm). With this new 3C-MAE technique, information on the level of scattering attributed to soot particles can be obtained. The experimental investigations are combined with radiative heat transfer computations to gain a comprehensive understanding of the radiative quenching of soot oxidation that happens at the flame tip responsible for soot release from the flame at the smoke point. In addition, the field of spectral scattering coefficient at 405 nm can be estimated, confirming that the non-scattering approximation is valid within the context of radiative models in this kind of flame. As a result, numerical simulations implementing radiative models without scattering should be able to decently capture the transition at the smoke point. Since the simulation of such a transition is crucial to the control of carbonaceous nanoparticles release process from flames, an original contribution of the present paper to this challenge is the supplemental material that contains the measured two-dimensional fields of both soot temperature and volume fraction.

Regular pyrometry techniques have been extensively used to infer the temperature field in sooting flames from soot luminosity. However, correction for soot self-absorption along the line-of-sight needs to be considered. The original contribution of the present paper is to assess both numerical and experimental uncertainties that can be attributed to the soot self-absorption effect on the soot temperature field measured by the two-color Modulated Absorption/Emission (2C-MAE) technique. Unlike for regular pyrometry techniques, the design of the 2C-MAE technique actually enables the direct measurement of the local spectral absorption coefficient field. The proportion of flame emission trapping caused by the soot along the line-of-sight is first simulated for different levels of soot loading ranges. The retrieved temperature error when self-absorption is neglected can then be quantified as a function of the level of soot loading and the detection spectral ranges of the technique. As a result, it is found that the proportion of the flame emission attenuation due to self-absorption is directly proportional to the soot volume fraction $$f_\mathrm{v}$$ and hardly depends on the temperature field to be retrieved. These trends are emphasized as the lower spectral range of detection is shifted towards the smaller wavelength. In addition, a linear correlation between the absolute temperature error and the peak $$f_\mathrm{v}$$ in the flame can be extracted and confirmed by experimental results. Eventually, it is also found that selecting detection spectral ranges centered at 645 nm and 785 nm offer the minimum temperature deviation when soot self-absorption is neglected for any conditions of soot loading level within the three studied spectral combinations. This finding is especially relevant for the identification of the optimal operating conditions required by regular 2C-pyrometry for the sooting flames considered.

The two-phase mixing layer formed between parallel gas and liquid streams is an important fundamental problem in turbulent multiphase flows. The problem is relevant to many industrial applications and natural phenomena, such as air-blast atomizers in fuel injection systems and breaking waves in the ocean. The velocity difference between the gas and liquid streams triggers an interfacial instability which can be convective or absolute depending on the stream properties and injection parameters. In the present study, a direct numerical simulation of a two-phase gas–liquid mixing layer that lie in the absolute instability regime is conducted. A dominant frequency is observed in the simulation and the numerical result agrees well with the prediction from viscous stability theory. As the interfacial wave plays a critical role in turbulence transition and development, the temporal evolution of turbulent fluctuations (such as the enstrophy) also exhibits a similar frequency. To investigate the statistical response of the multiphase turbulence flow, the simulation has been run for a long physical time so that time-averaging can be performed to yield the statistically converged results for Reynolds stresses and the turbulent kinetic energy (TKE) budget. An extensive mesh refinement study using from 8 million to about 4 billions cells has been performed. The turbulent dissipation is shown to be highly demanding on mesh resolution compared with other terms in TKE budget. The results obtained with the finest mesh are shown to be close to converged results of turbulent dissipation which allow us to obtain estimations of the Kolmogorov and Hinze scales. The estimated Kolmogorov scale is found to be similar to the cell size of the finest mesh used here. The computed Hinze scale is significantly larger than the size of droplets observed and does not seem to be a relevant length scale to describe the smallest size of droplets formed in atomization.

International audience; While auralization technology is used in a variety of fields, particularly in architectural acoustics, there is a lack of data on the auralization tools used and actual practices. In this perspective, this work presents the results of a survey study on auralization uses in the acoustical design and consulting community, targeting acoustical consultants. The objectives are (1) to identify the tools and methods used by acousticians to create auralizations as well as effective uses so as to understand the benefits and changes provided by this technology, and (2) to highlight the difficulties and limitations linked to the use of auralizations in concrete projects. Based on the theory of acceptability and use of technology, the study was conducted from a mix of quantitative and qualitative data collection approaches, combining a questionnaire answered by 74 respondents with semi-directed interviews with nine practitioners. Results highlight the main uses of auralizations, the diversity of projects in which auralizations are applied, and how auralizations are currently used in real-world situations. The benefits of using this technology, inherent weaknesses in the tools, and practical difficulties are also discussed.

This present study explores possible stabilization mechanisms in flickering, sooting, ethylene flames burning in varying density coflow and exposed to different levels of an upward gradient of the square of the magnetic flux density (∇(B2)). In normal gravity, flame flickering defines a natural large scale and low frequency flame oscillation that is induced by a so called modified Kelvin–Helmholtz type instability. To assess the potential of the magnetically induced stabilization process, a range of coflow mixtures with varying N2, O2, and CO2 contents in volume is studied. As a result, a domain of controllable flame stability is identified. Its extension depends on the maximum magnitude of ∇(B2), i.e., 18.2 T2/m for the present experimental setup. Spectral emission rate, spectral absorption coefficient, soot volume fraction, and soot temperature fields are measured in the flame by the Modulated Absorption/Emission technique (MAE). In agreement with former studies, the soot content is shown to play a key role in the stabilization process. Due to the magnetic force that is mainly acting on paramagnetic oxygen molecules, opposing gravity, and generated by ∇(B2), the residence time of soot particles in the flame presumably increases with ∇(B2). With growing soot volume fraction, radiative heat losses are enhanced leading to flame cooling. Therefore, flames exposed to the magnetic field exhibit both lower density gradients through the flame sheet and a weaker field of buoyant acceleration in the hot exhaust gas stream. Both mechanisms then reduce the flame vulnerability to the onset of oscillations due to modified Kelvin–Helmholtz type instabilities. The findings may be relevant for designing strategies to control the stability of oxyfuel combustion.

The derivation of shallow water models from Navier–Stokes equations is revisited yielding a class of two-layer shallow water models. An improved velocity profile is proposed, based on the superposition of an inviscid fluid and a viscous layer inspired by the Interactive Boundary Layer interaction used in aeronautics. This leads to a new friction law which depends not only on velocity and depth but also on the variations of velocity and thickness of the viscous layer. The resulting system is an extended shallow water model consisting of three depth-integrated equations: the first two are mass and momentum conservation in which a slight correction on hydrostatic pressure has been made; the third one, known as von Kármán equation, describes the evolution of the viscous layer. This coupled model is shown to be conditionally hyperbolic, and a Godunov-type finite volume scheme is also proposed. Several numerical examples are provided and compared to the Multi-Layer Saint-Venant model. They emphasize the ability of the model to deal with unsteady viscous effects. They illustrate also the phase-lag between friction and topography, and even recover possible reverse flows.

Since the seminal result of Kilian, Oblivious Transfer (OT) has proven to be a fundamental primitive in cryptography. In such a scheme, a user is able to gain access to an element owned by a server, without learning more than this single element, and without the server learning which element the user has accessed. The NIST call for post-quantum encryption and signature schemes has revived the interest for cryptographic protocols based on post-quantum assumptions and the need for secure post-quantum OT schemes. In this paper, we show how to construct an OT scheme based on lattices, from a collision-resistant chameleon hash scheme (CH) and a CCA encryption scheme accepting a smooth projective hash function (SPHF). Note that our scheme does not rely on random oracles and provides UC security against adaptive corruptions assuming reliable erasures.

International audience; We numerically investigate the stability and linear oscillatory behavior of a naturally diverging mass whose potential energy is harmonically modulated. It is known that in the Kapitza limit, i.e. when the period of modulation is much smaller than the diverging time, the collapsing mass can be dynamically stabilized and behave like an effective classic harmonic oscillator. We find that in the regime where the period of modulation is larger than the collapsing time of the mass, dynamical stabilization is still possible but in a discrete fashion. Only almost-periodic vibrational modes, or Floquet forms (FFs), are allowed that are located in independent stability stripes in the modulation parameter space. Reducing the FFs to their periodic eigenfunctions, one can transform the original equation of motion to a dimensionless Schrödinger stationary wave equation with a harmonic potential. This transformation allows for an analytical prediction of the stability stripes and the modal shapes of the vibrating mass. These results shed new light on the stability of linear dynamical systems, analytical solutions of Mathieu equations and on the relations between Initial and Boundary Value Problems.

Under shock loading, metals have been found to melt and with reflection of the shock wave from the material free surface, cavities nucleate and grow. This process is referred to as microspalling and has been the topic of several experimental investigations. Measurements during the cavity growth phase are not possible at present and we present here a Detailed Numerical Simulation of an idealized problem where we assume an inviscid, incompressible liquid subject to a constant expansion rate with cavities at a vanishing vapour pressure. To allow for a time-varying gas volume a free-surface interface condition has been implemented in an existing incompressible multiphase Navier--Stokes solver, PARIS , using a Volume-Of-Fluid method. The gas flow remains unsolved and is instead assumed to have a fixed pressure which is applied to the liquid through a Dirichlet boundary condition on the liquid-gas interface. Gas bubbles are tracked individually, allowing the gas pressure to be prescribed using a suitable equation of state. Simulations with hundreds of bubbles have been performed in a fixed domain under a constant rate of expansion. A bubble competition is observed: larger bubbles tend to expand more rapidly at the demise of smaller ones. The time scale of this competition is shown to depend on the Weber number.

International audience; This article is devoted to the micromechanical modelling of the time harmonic response of viscoelastic composites made of fractional Zener constituents. By extending previous results in classical viscoelasticity, new exact relations on time integrals of the effective relaxation spectrum are obtained. They are related to the intraphase second moments of the strain field in the asymptotic elastic regimes at low and high frequency. Based on these relations, the effective relaxation spectrum is approximated by a sum of two weighted Dirac delta functions. An attractive feature of this viscoelastic homogenization model is that it only involves the resolution of two elastic homogenization problems. This model is applied to estimate the response of particle reinforced two-phase composites. Its relevance is assessed by performing comparisons with FFT full-field simulations for distributions of polydisperse spherical particles.

International audience

International audience; Aim Constitutional thinness (CT) is a rare condition of natural low body weight, with no psychological issues, no marker of undernutrition and a resistance to weight gain. This study evaluated the skeletal muscle phenotype of CT women by comparison with a normal BMI control group. MethodsResultsTen CT women (BMI

In the context of the infrasound network of the International Monitoring System of CTBT, infrasounds and low- frequency sounds are reviewed as a method to characterize lightning flashes in a complementary way to electromagnetic observations. The physics of lightning discharges is briefly recalled, in relation with thunder characteristics and mechanisms of generation. The possibilities and limitations of following storms at various distances by means of remote acoustic detection of lightning flashes is discussed. Influence of distance, wind and ambient noise is examined. The three-dimensional reconstruction of lightning flashes is illustrated by several examples from a recent 2012 observation campaign in the French Mediterranean region. Comparison with outputs from a high-resolution electromagnetic lightning mapping array delineates the performances of acoustical reconstruction of individual lightning flashes for both intra-cloud or cloud-to-ground discharges. Analysis of a significant number of discharges allows to perform a statistical comparison of the two approaches. Special attention is brought to the lower parts of cloud-to-ground discharges. Opportunities for further investigations are finally outlined.

International audience; We present the extended results of a previous experiment [1] to assess the impact of individualized binaural rendering on player performance in the context of a VR " shooter game " , as part of a larger project to characterize the impact of binaural rendering quality in various VR applications. Participants played a game in which they were faced with successive enemy targets approaching from random directions on a sphere. Audiovisual cues allowed for target localization. Participants were equipped with an Oculus CV1-HMD, headphones, and two Oculus Touch hand tracked devices as targeting mechanisms. Participants performed six sessions alternatively using their best and worst-match HRTFs from a " perceptually orthogonal " optimized set of 7 HRTFs [2]. Results suggest that the impact of the HRTF on participant performance (speed and movement efficiency) depends both on participant sensitivity and HRTF presentation order.

Concurrent flame spread over electric wire insulation was studied experimentally in microgravity conditions during parabolic flights. Polyethylene insulated Nickel-Chrome wires and Copper wires were examined for external flow velocities ranging from 50 mm/s to 200 mm/s. The experimental results showed that steady state flame spread over wire insulation in microgravity could be achieved, even for concurrent flow. A theoretical analysis on the balance of heat supply from the flame to the unburned region, radiation heat loss from the surface to the ambient and required energy to sustain the flame propagation was carried out to explain the presence of steady spread over insulated wire under concurrent flow. Based on the theory, the change in heat input (defined by the balance between heat supply from flame and radiation heat loss) was drawn as a function of the flame spread rate. The curve intersected the linear line of the required energy to sustain the flame. This balance point evidences the existence of steady propagation in concurrent flow. Moreover, the estimated steady spread rate (1.2 mm/s) was consistent with the experimental result by considering the ratio of the actual flame length to the theoretical to be 0.5. Further experimental results showed that the concurrent flame spread rate increased with the external flow velocity. In addition, the steady spread rate was found to be faster for Copper wires than for Nickel-Chrome wires. The experimental results for upward spreading (concurrent spreading) in normal gravity were compared with the microgravity results. In normal gravity, the flame did not reach a steady state within the investigated parameter range. This is due to the fact that the fairly large flame spread rate prevented the aforementioned heat balance to be reached, which meant that such a spread rate could not be attained within the length of the tested sample.

We measured the acoustic absorption, on the 0.5-6 kHz frequency range, of polyurethane foams with mean pore diameters between 0.6 and 3.2 mm. Two types of foams were investigated: classical open-cells ones versus membrane foams, in which thin polyurethane membranes were preserved during solidification. Interestingly , the latter presented better absorption abilities, indicating that membranes could be an asset for sound absorption. Noise pollution has become a major problem in our modern life. Industrial and academic research has continuously tried to design more efficient soundproofing materials. Recently, exotic stuctures have been considered, using the concept of double-porosity 1,2 or introducing low frequency resonators to enhance the dissipation. 3–5 Traditionally , sound absorbers have been porous media, such as mineral wools or foams. A first general rule for their efficiency is that no obstacle should prevent the sound from propagating in the medium, otherwise the acoustic energy is reflected back instead of being absorbed. For foams, for example, it means that open-cell structures are preferred. On the other hand, the physical picture is that when sound penetrates such a medium, it loses a lot of energy because of the large surface area it can interact with. As a rule of thumb, one finds that good absorption is obtained when the typical pore size corresponds to the heat and viscous diffusive length in air, which is of the order of 50 µm at 2 kHz, for example. Hence, open-cell porous materials with pores sizes of tens of micrometers are good candidates for efficient sound absorption and are therefore used extensively for sound insulation. 6,7 In this letter we show that there are exceptions to these established rules: closed-cell foams with millimeter-sized pores can actually be good sound absorbers. The foams we studied were provided by the company Foampartner. They were made of polyurethane, with a porosity (air volume fraction) of 98%. Their most interesting feature, for us, was that most of the membranes which separate neighbouring pores (Fig. 1) were preserved during solidification. 8 As these membranes are not desired for most of the applications, the manufacturer employs a technique by which the membranes a) Electronic

We present a technique for determining the rheology of visco-elastic materials in the ultrasonic frequency range based on the measurement of the longitudinal and shear waves reflected and transmitted by a slab of material with a controlled thickness sandwiched between two delay lines. The high sensitivity of this Fabry-Perot resonator-based technique allows one to access characteristic relaxation times associated with visco-elasticity. As a useful application of the technique, we characterize the Olympus SWC-2 shear-wave couplant in the 0.7–5 MHz frequency range.We present a technique for determining the rheology of visco-elastic materials in the ultrasonic frequency range based on the measurement of the longitudinal and shear waves reflected and transmitted by a slab of material with a controlled thickness sandwiched between two delay lines. The high sensitivity of this Fabry-Perot resonator-based technique allows one to access characteristic relaxation times associated with visco-elasticity. As a useful application of the technique, we characterize the Olympus SWC-2 shear-wave couplant in the 0.7–5 MHz frequency range.

This study is devoted to the evaluation of the impact of both esters’ carbon chain length and concentration on sooting propensities of Diesel and Biodiesel surrogates. Soot particles were produced using a steady atmospheric axis-symmetric co-flow diffusion flame burner. Concentrations ranging from 3 to 30% (on molar basis) of methylbutanoate (MB), methyloctanoate (MO) or methyldecanoate (MD) were added to a surrogate Diesel made up of a binary mixture of 70% n-decane and 30% α-methylnaphthalene (α-MN). For every considered mixture, the sooting propensity was measured in terms of Yield Sooting Index (YSI) in a methane diffusion flame doped with 3.5% vapor of the mixture. Maps of soot volume fraction in the flame were extracted using a light extinction method (LEM). Soot samples produced along the combustion of surrogate Diesel and Biodiesel fuels were then collected and characterized using physico-chemical techniques, i.e. elemental analysis (CHONS), Thermogravimetric Analysis (TGA), Raman spectroscopy, and Temperature Programmed Oxidation (TPO). Results evidenced that ester functions contained in Biodiesel surrogates reduce soot production. This decrease was more pronounced when the concentration of the oxygenated additive investigated was higher. However, it has been surprisingly determined that YSI decreases when the aliphatic carbon chain of the ester additive is longer. On the other hand, physico-chemical characterizations of the generated model soot revealed that oxygen and soluble organic fraction (SOF) content decreases when the amount of biodiesel surrogate in the fuel increases. Nevertheless, no important dissimilarities have been registered in the graphitic structures of the different soot. Finally, the behavior towards oxidation reactivity indicated that the Biodiesel-derived soot were less reactive than the Diesel-derived one.