127,809 research outputs found
A Contribution to the Modal Identification of the Damping Factor based on the Dissipated Energy
ABSTRACT: The identification of the modal parameters from frequency response functions is a subject that is not new. However, the starting point often comes from the equations that govern the dynamic motion. In this paper, a novel approach is shown, resulting from an analysis that starts on the dissipated energy per cycle of vibration. For lightly damped systems with conveniently spaced modes, it produced quite accurate results in comparison to the direct application of the method of the inverse, both in the numerical and in the experimental examples. It also is a simple technique that can be used to produce quick estimates of the modal damping factors. Furthermore, this is also a contribution to further developments on modal analysis and identification methods as, up to today, the developed technique has not yet been proposed.Final Published versio
On the Nonrelativistic Limit of the phi^4 Theory in 2+1 Dimensions
We study the nonrelativistic limit of the quantum theory of a real scalar
field with quartic self-interaction. The two body scattering amplitude is
written in such way as to separate the contributions of high and low energy
intermediary states. From this result and the two loop computation of the self
energy correction, we determine an effective nonrelativistic action.Comment: 15 pages, 2 figures, revte
Symplectic Quantization for Reducible Systems
We study an extension of the symplectic formalism in order to quantize
reducible systems. We show that a procedure like {\it ghost-of-ghost} of the
BFV method can be applied in terms of Lagrange multipliers. We use the
developed formalism to quantize the antisymmetric Abelian gauge fields.Comment: 12 pages, IF-UFRJ-22/9
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