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Tudor Ratiu

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Publications associées (105)

Algebraic Complete Integrability of the Bloch-Iserles System

Tudor Ratiu

The goal of this paper is the proof of the algebraic complete integrability of the Bloch-Iserles Hamiltonian system [5]. This result was conjectured in [4], based on its validity in certain special cases. ...

Oxford University Press2015

Multisymplectic Lie group variational integrator for a geometrically exact beam in R3

Tudor Ratiu, François Gay-Balmaz, François Marie Alain Demoures

In this paper we develop, study, and test a Lie group multisymplectic integra- tor for geometrically exact beams based on the covariant Lagrangian formulation. We exploit the multisymplectic character of the integrator to analyze the energy and momentum ma ...

Elsevier2014

Feynman, Wigner, and Hamiltonian structures describing the dynamics of open quantum systems

Tudor Ratiu

Springer Verlag2014

Integrable G-strands on semisimple Lie groups

Tudor Ratiu, François Gay-Balmaz

The present paper derives systems of partial differential equations that admit a quadratic zero curvature representation for an arbitrary real semisimple Lie algebra. It also determines the general form of Hamilton's principles and Hamiltonians for these s ...

Iop Publishing Ltd2014

Nonexistence of smooth solutions for a full viscous isentropic liquid crystal system in three dimensions

Tudor Ratiu

We prove that the smooth solutions to the Cauchy problem for a full isentropic three-dimensional liquid crystal nematodynamic equations with conserved mass, linear momentum, and dissipating total energy, can lose classical smoothness within a finite time. ...

Elsevier2014

Moduli spaces of toric manifolds

Tudor Ratiu

We construct a distance on the moduli space of symplectic toric manifolds of dimension four. Then we study some basic topological properties of this space, in particular, path-connectedness, compactness, and completeness. The construction of the distance i ...

Springer Verlag2014

Spectral series of the Schrodinger operator with delta-potential on a three-dimensional spherically symmetric manifold

Tudor Ratiu

The spectral series of the Schrodinger operator with a delta-potential on a threedimensional compact spherically symmetric manifold in the semiclassical limit as h -> 0 are described. ...

Springer US2013

On the coupling between an ideal fluid and immersed particles

Mathieu Desbrun, Tudor Ratiu

In this paper, we present finite-dimensional particle-based models for fluids which respect a number of geometric properties of the Euler equations of motion. Specifically, we use Lagrange-Poincare reduction to understand the coupling between a fluid and a ...

Elsevier2013

Dirac Optimal Reduction

Tudor Ratiu, Madeleine Jotz

The purpose of this paper is to generalize the (Poisson) Optimal Reduction Theorem in Ortega and Ratiu [Momentum Maps and Hamiltonian Reduction. Progress in Mathematics 222. Boston, MA: Birkhauser. xxxiv, 497pp., 2004] to general proper Lie group actions o ...

Oxford University Press2013

Hamiltonian and Feynman Aspects of Secondary Quantization

Tudor Ratiu

Springer Verlag2013

Equivalent Theories of Liquid Crystal Dynamics

Tudor Ratiu, François Gay-Balmaz, Cesare Tronci

There are two competing descriptions of nematic liquid crystal dynamics: the Ericksen-Leslie director theory and the Eringen micropolar approach. Up to this day, these two descriptions have remained distinct in spite of several attempts to show that the mi ...

Springer Verlag2013

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

Exact geometric theory of dendronized polymer dynamics

Tudor Ratiu, François Gay-Balmaz

Dendronized polymers consist of an elastic backbone with a set of iterated branch structures (dendrimers) attached at every base point of the backbone. The conformations of such molecules depend on the elastic deformation of the backbone and the branches, ...

2012

Invariant Higher-Order Variational Problems II

Tudor Ratiu, François Gay-Balmaz

Motivated by applications in computational anatomy, we consider a second-order problem in the calculus of variations on object manifolds that are acted upon by Lie groups of smooth invertible transformations. This problem leads to solution curves known as ...

Springer Verlag2012

Invariant frames for vector bundles and applications

Tudor Ratiu, Madeleine Jotz

This paper completes a proof of the Dirac reduction theorem by involutive tangent subbundles. As a consequence, Dirac reduction by a proper Lie group action having one isotropy type is carried out. The main technical tool in the proof is the notion of part ...

Springer Verlag2012

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

Bifurcation diagram for the Kovalevskaya case on the lie algebra so(4)

Tudor Ratiu

Springer Verlag2012

Invariant Higher-Order Variational Problems

Tudor Ratiu, François Gay-Balmaz

We investigate higher-order geometric k-splines for template matching on Lie groups. This is motivated by the need to apply diffeomorphic template matching to a series of images, e.g., in longitudinal studies of Computational Anatomy. Our approach formulat ...

2012

Stability of Equilibria for the so(4) Free Rigid Body

Tudor Ratiu, Murat Turhan

The stability for all generic equilibria of the Lie-Poisson dynamics of the so(4) rigid body dynamics is completely determined. It is shown that for the generalized rigid body certain Cartan subalgebras (called of coordinate type) of so(n) are equilibrium ...

2012

Noncompact Lagrangian manifolds corresponding to the spectral series of the Schrodinger operator with delta-potential on a surface of revolution

Tudor Ratiu

SP MAIK Nauka/Interperiodica, Springer2012

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