1,238 research outputs found
Dissipativity preserving model reduction by retention of trajectories of minimal dissipation
We present a method for model reduction based on ideas from the behavioral theory of dissipative systems, in which the reduced order model is required to reproduce a subset of the set of trajectories of minimal dissipation of the original system. The passivity-preserving model reduction method of Antoulas (Syst Control Lett 54:361-374, 2005) and Sorensen (Syst Control Lett 54:347-360, 2005) is shown to be a particular case of this more general class of model reduction procedures
Stability of switched linear differential systems
We study the stability of switched systems where the dynamic modes are
described by systems of higher-order linear differential equations not
necessarily sharing the same state space. Concatenability of trajectories at
the switching instants is specified by gluing conditions, i.e. algebraic
conditions on the trajectories and their derivatives at the switching instant.
We provide sufficient conditions for stability based on LMIs for systems with
general gluing conditions. We also analyse the role of positive-realness in
providing sufficient polynomial-algebraic conditions for stability of two-modes
switched systems with special gluing conditions
Chaoticity and Dissipation of Nuclear Collective Motion in a Classical Model
We analyze the behavior of a gas of classical particles moving in a
two-dimensional "nuclear" billiard whose multipole-deformed walls undergo
periodic shape oscillations. We demonstrate that a single particle Hamiltonian
containing coupling terms between the particles' motion and the collective
coordinate induces a chaotic dynamics for any multipolarity, independently on
the geometry of the billiard. The absence of coupling terms allows us to
recover qualitatively the "wall formula" predictions. We also discuss the
dissipative behavior of the wall motion and its relation with the
order-to-chaos transition in the dynamics of the microscopic degrees of
freedom.Comment: LateX, 11 pages, 7 figures available on request, to appear in the
Proceedings of XXXIV Winter Meeting on Nuclear Physics, Bormio 22-27 January,
199
Assessment of fissionable material behaviour in fission chambers
A comprehensive study is performed in order to assess the pertinence of fission chambers coated with different fissile materials for high neutron flux detection. Three neutron scenarios are proposed to study the fast component of a high neutron flux: (i) high neutron flux with a significant thermal contribution such as BR2, (ii) DEMO magnetic fusion reactor, and (iii) IFMIF high flux test module.
In this study, the inventory code ACAB is used to analyze the following questions: (i) impact of different deposits in fission chambers; (ii) effect of the irradiation time/burn-up on the concentration; (iii) impact of activation cross-section uncertainties on the composition of the deposit for all the range of burn-up/irradiation neutron fluences of interest. The complete set of nuclear data (decay, fission yield, activation cross-sections, and uncertainties) provided in the EAF2007 data library are used for this evaluation
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