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M. Zuccalli

Publications and source records attributed to M. Zuccalli.

4 recordsLinked to original sources

Variational integrators using forced discrete Hamiltonian systems

We study discrete Hamiltonian systems defined on cotangent bundles that are subjected to external forces, whose trajectories are determined by a discrete variational principle. We analyze the evolution of the canonical symplectic structure and, when a Lie group of symmetries is present, the corresponding evolution of the associated momenta. Given a continuous forced Hamiltonian system, we construct an exact discrete analogue whose order-$r$ approximations yield trajectories that approximate the continuous ones with accuracy of at least order $r$. We also give two methods to build approximate discrete systems. Combining these, we obtain a variational integrator: first approximate the exact discrete system and then solve the resulting algebraic equations of motion.

math.DS

Dirac approach to constrained submanifolds in a double loop group: from WZNW to Poisson-Lie $σ$-model

We study the restriction to a family of second class constrained submanifolds in the cotangent bundle of a double Lie group, equipped with a 2-cocycle extended symplectic form, building the corresponding Dirac brackets. It is shown that, for a 2-cocycle vanishing on each isotropic subspaces of the associated Manin triple, the Dirac bracket contains no traces of the cocycle. We also investigate the restriction of the left translation action of the double Lie group on its cotangent bundle, where it fails in to be a symmetry a canonical transformation. However, the hamiltonian symmetry is restored on some special submanifolds. The main application is on loop groups, showing that a WZNW-type model on the double Lie group with a quadratic Hamilton function in the momentum maps associated with the left translation action on the cotangent bundle with the canonical symplectic form, restricts to a collective system on some special submanifolds. There, the lagrangian version coincides with so called Poisson-Lie $σ$-model.

math-ph

Optimal Control of Underactuated Mechanical Systems: A Geometric Approach

In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

math-ph

Poisson-Lie T-Duality and non trivial monodromies

We describe a general framework for studying duality between different phase spaces which share the same symmetry group $\mathrm{H}$. Solutions corresponding to collective dynamics become dual in the sense that they are generated by the same curve in $\mathrm{H}$. Explicit examples of phase spaces which are dual with respect to a common non trivial coadjoint orbit $\mathcal{O}_{c,0}(\mathbfα,1) \subset\mathfrak{h}^{\ast}$ are constructed on the cotangent bundles of the factors of a double Lie group $\mathrm{H}=\mathrm{N}\Join\mathrm{N}^{\ast}$. In the case $\mathrm{H}=LD$, the loop group of a Drinfeld double Lie group $D$, a hamiltonian description of Poisson-Lie T-duality for non trivial monodromies and its relation with non trivial coadjoint orbits is obtained.

math-ph