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Concept

Action (physique)

Publications associées (26)

How Lagrangian States Evolve Into Random Waves

Alejandro Rivera

In this paper, we consider a compact connected manifold (X, g) of negative curvature, and a family of semi-classical Lagrangian states f(h)(x) = a(x)e(i phi(x)/h) on X. For a wide family of phases phi, we show that f(h), when evolved by the semi-classical ...

ECOLE POLYTECHNIQUE2022

Polymer Translocation through Nanometer Pores

Maria-Alexandra Paun

In this paper the loaded polymer transport and its escape via a nanometer size aperture, virtually by nanomembrane, the polymer being moved by an exterior electrostatic field, has been studied. Assuming a linear dependency of the friction coefficient on th ...

MDPI2022

Phare de la Jument en mer d'iroise – Réponse structurale sous l'action de vagues déferlantes

Emmanuel Denarié

Les phares en mer constituent un patrimoine historique remarquable, souvent âgé de plus de 100 ans. La gestion de leur vieillissement est un défi et nécessite une compréhension approfondie de leur réponse structurale sous l'action des vagues. La réponse dy ...

Nathalie Domède & Frédéric Dubois2021

Stability of a Point Charge for the Vlasov–Poisson System: The Radial Case

Klaus Martin Widmayer

We consider the Vlasov–Poisson system with repulsive interactions. For initial data a small, radial, absolutely continuous perturbation of a point charge, we show that the solution is global and disperses to infinity via a modified scattering along traject ...

2021

Semiclassical analysis of the quantum instanton approximation

Jiri Vanicek, Christophe Louis Joseph Jean-Luc Vaillant

We explore the relation between the quantum and semiclassical instanton approximations for the reaction rate constant. From the quantum instanton expression, we analyze the contributions to the rate constant in terms of minimum-action paths and find that t ...

2019

Automatic extraction of constraints in manipulation tasks for autonomy and interaction

Ana-Lucia Ureche

Tasks routinely executed by humans involve sequences of actions performed with high dexterity and coordination. Fully specifying these actions such that a robot could replicate the task is often difficult. Furthermore the uncertainties introduced by the us ...

EPFL2018

Extreme Values of Lightning Parameters

Marcos Rubinstein, Aleksandr Smorgonskii

In this paper we present an online database where we have collected a number of reports on extreme lightning parameters: peak current, fastest and slowest rise time, fastest and slowest time to half value, rate of change of current, flash duration, charge ...

2018

Scale-invariant alternatives to general relativity. II. Dilaton properties

Mikhail Chapochnikov, Georgios Karananas

In the present paper, we revisit gravitational theories which are invariant under TDiffs-transverse (volume-preserving) diffeomorphisms and global scale transformations. It is known that these theories can be rewritten in an equivalent diffeomorphism-invar ...

American Physical Society2016

Path integral approach to the quantum fidelity amplitude

Jiri Vanicek

The Loschmidt echo is a measure of quantum irreversibility and is determined by the fidelity amplitude of an imperfect time-reversal protocol. Fidelity amplitude plays an important role both in the foundations of quantum mechanics and its applications, suc ...

Royal Soc2016

Asymptotics of action variables near semi-toric singularities

The presence of focus-focus singularities in semi-toric integrables Hamiltonian systems is one of the reasons why there cannot exist global Action-Angle coordinates on such systems. At focus-focus critical points, the Liouville-Arnold-Mineur theorem does n ...

Elsevier2015

Assessment of phase-field-crystal concepts using long-time molecular dynamics

William Curtin

The ability of the phase-field-crystal (PFC) model to quantitatively predict atomistic defect structures in crystalline solids is addressed. First, general aspects of the PFC model are discussed within the context of obtaining quantitative results in solid ...

American Physical Society2015

Multiphysics simulation of corona discharge induced ionic wind

Ivica Stevanovic, Nicola Parolini

Ionic wind devices or electrostatic fluid accelerators are becoming of increasing interest as tools for thermal management, in particular for semiconductor devices. In this work, we present a numerical model for predicting the performance of such devices; ...

American Institute of Physics2013

Extensions of Lie-Rinehart algebras and cotangent bundle reduction

Tudor Ratiu

Let Q denote a smooth manifold acted upon smoothly by a Lie group G. The G-action lifts to an action on the total space TQ of the cotangent bundle of Q and hence on the standard symplectic Poisson algebra of smooth functions on TQ. The Poisson algebra of ...

Oxford University Press2013

Reduced Variational Formulations in Free Boundary Continuum Mechanics

Tudor Ratiu, François Gay-Balmaz

We present the material, spatial, and convective representations for elasticity and fluids with a free boundary from the Lagrangian reduction point of view, using the material and spatial symmetries of these systems. The associated constrained variational ...

Springer-Verlag2012

The Effect of Scale on the Applicability of Taylor’s Frozen Turbulence Hypothesis in the Atmospheric Boundary Layer

Marc Parlange, Valentin Simeonov, Chad Higgins, Martin Froidevaux, Nikki Vercauteren, Caitlin Ellen Barry

Taylor’s frozen turbulence hypothesis is the central assumption invoked in most experiments designed to investigate turbulence physics with time resolving sensors. It is also frequently used in theoretical discussions when linking Lagrangian to Eulerian fl ...

2012

Accelerating the calculation of time-resolved electronic spectra with the cellular dephasing representation

Jiri Vanicek, Miroslav Sulc

Dephasing representation of fidelity, also known as the phase averaging method, can be considered as a special case of Miller's linearized semiclassical initial value representation and belongs among the most efficient approximate semiclassical approaches ...

Taylor & Francis2012

Reduction strategies for PDE-constrained optimization problems in haemodynamics

Gianluigi Rozza, Andrea Manzoni, Federico Negri

Solving optimal control problems for many different scenarios obtained by varying a set of parameters in the state system is a computationally extensive task. In this paper we present a new reduced framework for the formulation, the analysis and the numeri ...

Vienna Technical University2012

Higher order Lagrange-Poincar, and Hamilton-Poincar, reductions

Tudor Ratiu, François Gay-Balmaz

Motivated by the problem of longitudinal data assimilation, e.g., in the registration of a sequence of images, we develop the higher-order framework for Lagrangian and Hamiltonian reduction by symmetry in geometric mechanics. In particular, we obtain the r ...

2011

Lagrange-Poincare field equations

Tudor Ratiu, François Gay-Balmaz

The Lagrange-Poincare equations of classical mechanics are cast into a field theoretic context together with their associated constrained variational principle. An integrability/reconstruction condition is established that relates solutions of the original ...

2011

A Hamilton-Jacobi Formulation for Cooperative Control of Multi-Agent Systems

Denis Gillet

Coordination of autonomous non-point agents is studied in this work. Interactions between vehicles together with their internal dynamics have been modeled as a continuous, unconstrained differential game. In particular, collision prediction is shown to be ...

2009