This article presents an imaging technique to locate a weak perturbation in multiple scattering environment. We derive formula predict the spatiotemporal decorrelation of diffuse coda waves induced by extra scatterer. Locating this new defect is formulated as inverse problem which solved maximum likelihood approach. Using elastic 50–400 kHz frequency band, we recover position millimetric hole drilled concrete sample with precision few centimeter. Note that size comparable myriads...

Long ranged electrostatic interactions are time consuming to calculate in molecular dynamics and Monte Carlo simulations. We introduce an algorithmic framework for simulating charged particles which modifies the so as allow equilibration using a local Hamiltonian. The method introduces auxiliary field with constrained that equilibrium distribution is determined by Coulomb interaction. demonstrate efficiency of simple, lattice gas.

We report on theoretical predictions of the decorrelation and phase-shift coda waves induced by local changes in multiple scattering media. Using formalism, we show that both expressions (decorrelation phase-shift) involve a same sensitivity kernel based intensity transport medium. compare kernels diffusion approximation with ones radiative transfer approximation, showing latter is more accurate at short times or for located close to source receiver. also perform series numerical simulations...

We describe a time-resolved monitoring technique for heterogeneous media. Our approach is based on the spatial variations of cross-coherence diffuse waves acquired at fixed positions but different dates. The applies to all kind waves, provided that waveforms can be with sampling frequency much larger than wave frequency. To locate and characterize weak change occurred between successive acquisitions, we use maximum likelihood combined diffusive propagation model. this technique, locating...

This study focuses on imaging local changes in heterogeneous media. The method employed is demonstrated and validated using numerical experiments of acoustic wave propagation a multiple scattering medium. Changes are simulated by adding new scatterers different sizes at various positions the medium, induced decorrelation diffuse (coda) waveforms measured for pairs sensors. spatial temporal dependences modeled through sensitivity kernel, based intensity transport inverse problem then solved...

Eric Larose, a) Thomas Planes, Vincent Rossetto, and Ludovic Margerin Lab. de Geophysique Interne et Tectonophysique, CNRS & Univ. J. Fourier, BP53, 38041 Grenoble, France. Physique Modelisation des Milieux Condenses, BP 166, 38042 Centre Europeen Recherche d’Enseignement Geosciences l’Environnement, Aix Marseille Europole Mediterraneen l’Arbois, 80, 13545 en Provence, France

Turbulence is a ubiquitous phenomenon in natural and industrial flows. Since the celebrated work of Kolmogorov 1941, understanding statistical properties fully developed turbulence has remained major quest. In particular, deriving turbulent flows from mesoscopic description, that is, Navier-Stokes equation, eluded most theoretical attempts. Here, we provide prediction for functional space time dependence velocity-velocity correlation function homogeneous isotropic field theory associated to...

A crossover from a Kolmogorov decay of two decades in the inertial range to stretched exponential dissipative is unveiled experimental spatial energy spectrum turbulent swirling flow, as recently predicted based on nonperturbative renormalization group theory.

Motivated by recent experiments on DNA torsion-force-extension characteristics we consider the writhing geometry of open stiff molecules. We exhibit a cyclic motion which allows arbitrarily large twisting end molecule via an activated process. This process is suppressed for forces larger than femto-Newtons us to show that are sensitive generalization Calugareanu-White formula writhe. Using numerical methods compare this formulation writhe with analytic calculations.

The stiffness of a consolidated granular medium experiences drop immediately after moderate mechanical solicitation. Then the rises back toward its initial value, following logarithmic time evolution called slow dynamics. In literature, dynamics has been probed by macroscopic quantities averaged over sample volume, for instance, resonant frequency vibrational eigenmodes. This article presents different approach based on diffuse acoustic wave spectroscopy, technique that is directly sensitive...

We use direct numerical simulations (DNSs) of the forced Navier–Stokes equation for a three-dimensional incompressible fluid in order to test recent theoretical predictions. study two- and three-point spatiotemporal correlation functions velocity field stationary, isotropic, homogeneous turbulence. compare our results predictions from Functional Renormalization Group (FRG) which were obtained large wavenumber limit. DNSs are performed at various Reynolds numbers correlations analyzed...

To determine how a fluid carries its energy down to microscopic scales where it is dissipated, result from the assumption-free theory of nonperturbative renormalization group was tested, using numerical simulations and data ONERA wind tunnel. The findings confirm that kinetic spectrum follows predicted stretched exponential in dissipation range .

Persistent random walks are intermediate transport processes between a uniform rectilinear motion and Brownian motion. They formed by successive steps of finite lengths directions travelled at fixed speed. The isotropic symmetric one-dimensional persistent walk is governed the telegrapher's equation, also called hyperbolic heat conduction equation. These equations have been designed to resolve paradox infinite speed in diffusion equations. finiteness both correlation length leads several...

Using direct numerical simulations we study the spatiotemporal correlations of passive scalars advected both by Navier-Stokes flow and synthetic velocity fields. Beyond their global behavior, which is either a Gaussian or an exponential decay in time, depending on carrier flow, determine with accuracy prefactors exponents, find remarkable agreement recent results from functional renormalization group.

We formulate a framework to extend the idea of Berry's topological phase multiple light scattering, and in particular backscattering linearly polarized light. show that randomization geometric phases medium leads loss polarization degree light, i.e., depolarization. use Monte Carlo simulations which is calculated for each photon path. Then we average over distribution calculate form patterns, compare with experimental patterns formed by backscattered between crossed or parallel polarizers.

We analyse the statistics of phase fluctuations seismic signals obtained from a temporary small aperture array deployed on volcano in French Auvergne. demonstrate that field satisfies Circular Gaussian statistics. then determine scattering mean free path Rayleigh waves spatial decoherence. This phenomenon, observed for diffuse wavefields, is found to yield good approximation path. Contrary amplitude, decoherence absorption effects and provides direct access

We study theoretically the polarization state of light in multiple scattering media limit weak gradients refractive index. Linearly polarized photons are randomly rotated due to Berry phase associated with path. For circularly independent speckle patterns found for two helical states. The statistics geometric is related writhe distribution semiflexible polymers such as DNA.

This article presents an imaging technique to locate a weak perturbation in multiple scattering environment. We focus on concrete probed by ultrasound. derive formula predict the spatiotemporal decorrelation of diffuse coda waves induced extra scatterer. solve inverse problem with maximum likelihood approach. Using elastic 50-400 kHz frequency band, we recover position millimetric holes drilled sample precision few centimeters.

Local time is the measure of how much a random walk has visited given position. In multiple scattering media, where waves are diffuse, local measures sensitivity to medium's properties. variations absorption, velocity and between two measurements yield in wave field. These proportionnal volume change happened amplitude variation. The field measured using correlations can be used as input inversion algorithm produce variation maps. present article gives expression dimensions one, three an its...

The modelling of DNA mechanics under external constraints is discussed. Two analytical models are widely known, but disagree for instance on the value torsional modulus. origin this embarassing situation located in concept writhe. This letter presents a unified model establishing relation between different approaches. I show that writhe created by loops at discrepancy. To take into account, propose new treatment loop statistics based numerical simulations using most general formula writhe,...

We develop a framework for the multiple scattering of polarized wave. consider particles with spin propagating in medium filled scatterers. write amplitudes each eigenstate local, mobile frame. One axes is direction propagation particle. use this representation to define directional Green's operator homogeneous and also spin-dependent amplitudes. show that reveals Berry phase. establish generalized Green-Dyson equation problem framework. can be solved by linear algebra if one uses rotations...

The stiffness of concrete experiences a drop immediately after moderate mechanical solicitation. Then the rises back logarithmically toward its initial value. This Slow Dynamics behavior has been probed by macroscopic quantities averaged over sample volume, including resonant frequency. article presents different approach based on diffuse acoustic wave spectroscopy, technique that is directly sensitive to details structure. parameters dynamics are found depend and thermal damage medium....