We here present the complete analysis of experiments on driven Brownian motion and electric noise... more We here present the complete analysis of experiments on driven Brownian motion and electric noise in a RC circuit, showing that thermodynamic entropy production can be related to the breaking of time-reversal symmetry in the statistical description of these nonequilibrium systems. The symmetry breaking can be expressed in terms of dynamical entropies per unit time, one for the forward process and the other for the time-reversed process. These entropies per unit time characterize dynamical randomness, i.e., temporal disorder, in time series of the nonequilibrium fluctuations. Their difference gives the well-known thermodynamic entropy production, which thus finds its origin in the time asymmetry of dynamical randomness, alias temporal disorder, in systems driven out of equilibrium.
The surface quality of a workpiece, as it is finished by the tooling machine, can be translated i... more The surface quality of a workpiece, as it is finished by the tooling machine, can be translated into a set of numbers (one or more) which depend on the specific measuring procedures. We illustrate this with respect to the three classes of profilometer techniques either available or suggested, namely: mechanical profilometers, detection of the angular scattering diagram, speckle correlation. A mechanical profilometer yields a value of roughness averaged over the size of a diamond point which fingers the surface [1 ]. Furthermore, the diamond finger is cut at a given angle (e.g. 45°), and the measurement o f a roughness profile steeper than that would give wrong values. Hence, associated information has a resolution limited by the above size and steepness requirements. In the second case, using scattering techniques, the surface is illuminated by an e.m. wave (either at microwave or optical frequencies) and the angular distribution of the scattered intensity is associated with the ave...
New Trends in Nonlinear Dynamics and Pattern-Forming Phenomena, 1990
Convective patterns with different symmetries can develop in RayleighBenard convection. When the ... more Convective patterns with different symmetries can develop in RayleighBenard convection. When the transport coefficients of the fluid are temperature dependent (non-Boussinesq conditions) a hexagonal pattern is stable near threshold, but it is replaced by a pattern of rolls when the heating rate is increased still further. We present here recent experimental results on the transition between a hexagonal pattern and a pattern of rolls in convection in pure water under non-Boussinesq conditions. The convective cell is cylindrical with a liquid depth d = 2.00 mm and a diameter D = 72 mm. This gives an aspect ratio F = D/2d = 18. The Prandtl number of water at the mean temperature of 28°C is P = 5.81. The general features of the pattern are determined qualitatively by a shadowgraph technique. Heat-flow and optical measurements enable us to obtain quantitatively local and global characteristics of the pattern. The optical technique is based on the deflections of a laser beam that crosses the fluid layer in the vertical direction. This technique allow us to reconstruct the temperature field averaged on the vertical direction. More details about the experimental set-up can be found elsewhere.1
Experimental results concerning the interaction of a fully developed turbulent flow with a pertur... more Experimental results concerning the interaction of a fully developed turbulent flow with a perturbation properly generated in the physical domain, are presented. By means of a conditional averaging technique, it has been possible to extract informations on the response function of the turbulent flow. Satisfactory agreement with the DIA Kraichnan’s theory prediction, is also observed.
Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degr... more Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degrees of freedom in a complex spatiotemporal dynamics. The method has been applied on experimental and numerical data. In both cases the number of degrees of freedom found by this method is very close to the fractal dimension of the attractor or the Lyapunov dimension.
Surface waves instability has been experimentally studied in a cylindrical basin subjected to a h... more Surface waves instability has been experimentally studied in a cylindrical basin subjected to a horizontal oscillation. We show that the presence of two modes, respectively parallel and perpendicular to the direction of the forcing, may produce either a stable or a time-dependent superposition of the two modes. The phase diagram of the system, the surface deformation amplitude and the features
Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simul... more Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simulations, and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy cascade are tested. Leading and subleading contribution, in the inertial range, can be explained as arising from a multiplicative random process for the energy transfer mechanisms. Two different predictions for correlations involving dissipative observable are also briefly discussed.
Proceedings of the 3rd Seminaire Rhodanien De Physique Held in Dolomieu France March 13 17 1995 Gif Sur Yvette Editions Frontiers C1995 Edited By Ciliberto S Dauxois T Droz M, 1995
We here present the complete analysis of experiments on driven Brownian motion and electric noise... more We here present the complete analysis of experiments on driven Brownian motion and electric noise in a RC circuit, showing that thermodynamic entropy production can be related to the breaking of time-reversal symmetry in the statistical description of these nonequilibrium systems. The symmetry breaking can be expressed in terms of dynamical entropies per unit time, one for the forward process and the other for the time-reversed process. These entropies per unit time characterize dynamical randomness, i.e., temporal disorder, in time series of the nonequilibrium fluctuations. Their difference gives the well-known thermodynamic entropy production, which thus finds its origin in the time asymmetry of dynamical randomness, alias temporal disorder, in systems driven out of equilibrium.
The surface quality of a workpiece, as it is finished by the tooling machine, can be translated i... more The surface quality of a workpiece, as it is finished by the tooling machine, can be translated into a set of numbers (one or more) which depend on the specific measuring procedures. We illustrate this with respect to the three classes of profilometer techniques either available or suggested, namely: mechanical profilometers, detection of the angular scattering diagram, speckle correlation. A mechanical profilometer yields a value of roughness averaged over the size of a diamond point which fingers the surface [1 ]. Furthermore, the diamond finger is cut at a given angle (e.g. 45°), and the measurement o f a roughness profile steeper than that would give wrong values. Hence, associated information has a resolution limited by the above size and steepness requirements. In the second case, using scattering techniques, the surface is illuminated by an e.m. wave (either at microwave or optical frequencies) and the angular distribution of the scattered intensity is associated with the ave...
New Trends in Nonlinear Dynamics and Pattern-Forming Phenomena, 1990
Convective patterns with different symmetries can develop in RayleighBenard convection. When the ... more Convective patterns with different symmetries can develop in RayleighBenard convection. When the transport coefficients of the fluid are temperature dependent (non-Boussinesq conditions) a hexagonal pattern is stable near threshold, but it is replaced by a pattern of rolls when the heating rate is increased still further. We present here recent experimental results on the transition between a hexagonal pattern and a pattern of rolls in convection in pure water under non-Boussinesq conditions. The convective cell is cylindrical with a liquid depth d = 2.00 mm and a diameter D = 72 mm. This gives an aspect ratio F = D/2d = 18. The Prandtl number of water at the mean temperature of 28°C is P = 5.81. The general features of the pattern are determined qualitatively by a shadowgraph technique. Heat-flow and optical measurements enable us to obtain quantitatively local and global characteristics of the pattern. The optical technique is based on the deflections of a laser beam that crosses the fluid layer in the vertical direction. This technique allow us to reconstruct the temperature field averaged on the vertical direction. More details about the experimental set-up can be found elsewhere.1
Experimental results concerning the interaction of a fully developed turbulent flow with a pertur... more Experimental results concerning the interaction of a fully developed turbulent flow with a perturbation properly generated in the physical domain, are presented. By means of a conditional averaging technique, it has been possible to extract informations on the response function of the turbulent flow. Satisfactory agreement with the DIA Kraichnan’s theory prediction, is also observed.
Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degr... more Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degrees of freedom in a complex spatiotemporal dynamics. The method has been applied on experimental and numerical data. In both cases the number of degrees of freedom found by this method is very close to the fractal dimension of the attractor or the Lyapunov dimension.
Surface waves instability has been experimentally studied in a cylindrical basin subjected to a h... more Surface waves instability has been experimentally studied in a cylindrical basin subjected to a horizontal oscillation. We show that the presence of two modes, respectively parallel and perpendicular to the direction of the forcing, may produce either a stable or a time-dependent superposition of the two modes. The phase diagram of the system, the surface deformation amplitude and the features
Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simul... more Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simulations, and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy cascade are tested. Leading and subleading contribution, in the inertial range, can be explained as arising from a multiplicative random process for the energy transfer mechanisms. Two different predictions for correlations involving dissipative observable are also briefly discussed.
Proceedings of the 3rd Seminaire Rhodanien De Physique Held in Dolomieu France March 13 17 1995 Gif Sur Yvette Editions Frontiers C1995 Edited By Ciliberto S Dauxois T Droz M, 1995
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