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The main contribution of this paper is the derivation of spatiotemporal Liénard-type models for expressing the dynamical behavior of a fluid transmission line. The derivation is carried out from a quasilinear hyperbolic system made of a momentum equation and a continuity one. An advantage of these types of models is that they are suitable for formulating estimation algorithms. This claim is confirmed in the present paper for the case of fluid dynamics, since the article presents the conception and evaluation of a Liénard model-based observer that estimates the parameters of a pipeline such as the friction factor, the equivalent length and the wave speed. To show the potentiality of the approach, results based on some simulation and experimental tests are presented. [ABSTRACT FROM AUTHOR]

Abstract: The damping properties estimation assumes a viscoelastic model calibrated from experiments and simulations. This Note presents a gradient method for viscoelastic behaviour identification of damped sandwich structures devoted to the passive control of mechanical vibration. The method combines experimental data, numerical simulations realized with a complex non-linear eigenvalue solver using the asymptotic numerical method, and optimal control for the identification of viscoelastic parameters. An automatic differentiation tool is used to get numerical derivatives exact up to the machine precision with minimal user effort. Results are presented for a sandwich beam with a frequency dependent viscoelastic core. [Copyright &y& Elsevier]