163,310 research outputs found
J. O. Fleckenstein, G. W. Leibniz, Barock und Universalismus
No full textRobinet André. J. O. Fleckenstein, G. W. Leibniz, Barock und Universalismus. In: Revue d'histoire des sciences et de leurs applications, tome 12, n°3, 1959. pp. 275-276
J. O. Fleckenstein, G. W. Leibniz, Barock und Universalismus
No full textRobinet André. J. O. Fleckenstein, G. W. Leibniz, Barock und Universalismus. In: Revue d'histoire des sciences et de leurs applications, tome 12, n°3, 1959. pp. 275-276
Kidder Smith, Peter K. Bol, Jr., Joseph A. Adler, Don J. Wyatt, Sung dynasty uses of the I Ching, 1990
No full textRobinet I. Kidder Smith, Peter K. Bol, Jr., Joseph A. Adler, Don J. Wyatt, Sung dynasty uses of the I Ching, 1990. In: Études chinoises, vol. 9, n°2, Automne 1990. pp. 181-185
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Guichard, J., Bangali, M., Cohen-Scali, V., Pouyaud, J., & Robinet, M.-L. Concevoir et orienter sa vie : les dialogues de conseil en life design.
No full textL’ouvrage de J. Guichard, M. Bangali, V. Cohen-Scali, J. Pouyaud et M-L. Robinet s’adresse avant tout aux (futurs) professionnels de l’accompagnement en orientation. Il présente les enjeux actuels de la pratique d’une forme particulière d’accompagnement : les « dialogues de conseil en life design » (DCLD). Dans cet objectif, les cinq chapitres proposés permettent d’aller bien au-delà des seuls aspects méthodologiques. Le chapitre introductif attire notamment l’attention sur l’importance de re..
A purely nonlinear route to transition approaching the edge of chaos in a boundary layer
No full textPublisher version : http://iopscience.iop.org/1873-7005/44/3/031404The understanding of transition in shear flows has recently progressed along new paradigms based on the central role of coherent flow structures and their nonlinear interactions. We follow such paradigms to identify, by means of a nonlinear optimization of the energy growth at short time, the initial perturbation which most easily induces transition in a boundary layer. Moreover, a bisection procedure has been used to identify localized flow structures living on the edge of chaos, found to be populated by hairpin vortices and streaks. Such an edge structure appears to act as a relative attractor for the trajectory of the laminar base state perturbed by the initial finite-amplitude disturbances, mediating the route to turbulence of the flow, via the triggering of a regeneration cycle of Lambda and hairpin structures at different space and time scales. These findings introduce a new, purely nonlinear scenario of transition in a boundary-layer flow
Nonlinear optimal perturbation of turbulent channel flow as a precursor of extreme events
No full textThis work aims at studying the mechanisms behind the occurrence of extreme dissipation events in a channel flow, identifying nonlinear optimal perturbations as potential precursors of these events. Nonlinear optimal perturbations with respect to a generic turbulent instantaneous snapshot are computed for the first time using a direct-adjoint algorithm in the channel flow at Reτ ≈ 180. The resulting initial perturbation displays the upstream tilting characteristic of Orr's mechanism and is positioned along the interfaces between two opposite-sign velocity streaks of the pre-existing turbulent field. Such a perturbation induces a sudden breakdown of the pre-existing structures and a heavier tail in the dissipation probability density function distribution. Different mechanisms are at play during this process: the high shear present at the interface between coherent low- and high-momentum regions is exploited to break down the larger structures and drive energy to small scales. This energy cascade is fed by an enhanced lift-up effect that produces intense streaks near the wall. It is found that the optimal perturbation grows exponentially during the first phase of its evolution reflecting the existence of a secondary modal instability of the streaks. To corroborate the results, the conditional spatiotemporal proper orthogonal decomposition (POD) analysis of Hack & Schimdt (J. Fluid Mech., vol. 907, 2021, A9) is performed both in the perturbed and in the unperturbed flow, showing a clear agreement between the two cases and with the reference study. Thus, the optimal perturbation at initial time can be considered as a precursor of extreme events
Large-scale coherent structures in turbulent channel flow: a detuned instability of wall streaks
No full textIn this paper it is shown that a modal detuned instability of periodic near-wall streaks originates a large-scale structure in the bulk of the turbulent channel flow. The effect of incoherent turbulent fluctuations is included in the linear operator by means of an eddy viscosity. The base flow is an array of periodic two-dimensional streaks, extracted from numerical simulations in small domains, superposed to the turbulent mean profile. The stability problem for a large number of periodic units is efficiently solved using the block-circulant matrix method proposed by Schmid et al. (Phys. Rev. Fluids, vol. 2, 2017, 113902). For friction Reynolds numbers equal or higher than, it is shown that an unstable branch is present in the eigenspectra. The most unstable eigenmodes display large-scale modulations whose characteristic wavelengths are compatible with the large-scale end of the premultiplied velocity fluctuation spectra reported in previous computational studies. The wall-normal location of the large-wavelength near-wall peak in the spanwise spectrum of the eigenmode exhibits a power-law dependence on the friction Reynolds number, similarly to that found in experiments of pipes and boundary layers. Lastly, the shape of the eigenmode in the streamwise-wall-normal plane is reminiscent of the superstructures reported in the recent experiments of Deshpande et al. (J. Fluid Mech., vol. 969, 2023, A10). Therefore, there is evidence that such large-wavelength instabilities generate large-scale motions in wall-bounded turbulent flows
Frédéric Barbier, Le Patronat du Nord sous le Second Empire : Une approche prosopographique, avec la collaboration de J.-P. Daviet, A. Delmotte, P. Delsalle, C. Dhérent, J.-P. Hirsch, M. Leblond, P. Pouchain, R. Robinet, M. Vangheluwe, 1989
No full textHardy-Hémery Odette. Frédéric Barbier, Le Patronat du Nord sous le Second Empire : Une approche prosopographique, avec la collaboration de J.-P. Daviet, A. Delmotte, P. Delsalle, C. Dhérent, J.-P. Hirsch, M. Leblond, P. Pouchain, R. Robinet, M. Vangheluwe, 1989. In: Revue du Nord, tome 72, n°285, Avril-juin 1990. pp. 390-392
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