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Parameters identification of nonstationary systems is a very challenging topic that has only recently received critical attention from the research community. Aim of the paper is the structural health monitoring of bridge-like structures excited by a massive moving load, whose characteristics, such as the mass and speed, are unknown, in the presence of a localized damage along the structure. A novel method for the simultaneous identification of both the load characteristics and damage parameters from vibration measurements is proposed: the data processing relies on the ensemble empirical mode decomposition and the normalized Hilbert transform. Neither a priori information about the response of the undamaged structure nor the free decay of the damaged system is required, only a single-point measurement is needed. The empirical instantaneous frequency is firstly employed to estimate the load characteristics; secondly, the effect of the moving mass is filtered from the instantaneous frequency, and then, the damage position is identified. The performance of the technique are studied varying the load characteristics, damage locations, and crack depths. The effect of ambient noise is also taken into account. Numerical experiments show the identification is rather accurate, results are not very sensitive to the crack location and depth, while they are sensibly affected by the speed of the moving load. [ABSTRACT FROM AUTHOR]

The theory of vibration of engineering structures belongs to a known chapter of mechanics. Nevertheless, new emerging technologies operating at the smallest scales open a completely new landscape in the field of nanodevices, nanostructured materials as well as biological systems. Nanoscale structures are always involved and characterized by extremely high-frequency vibrations and very small energy, implying quantum effects. This approach, even for simple oscillators, implies both conceptual and mathematical difficulties. It is a matter of fact that the analysis of complex structures, as for example beams and shells, has never been considered in the physical and engineering recent literature in a complete quantum-mechanical context using directly the Schrodinger's equation. The present paper proposes an attempt in this direction, introducing a quantum Euler beam, the QUEB model at the ground state energy. The idea is to shape a new model for flexural structures that is mathematically similar to those used in classical mechanics, but mimicking the peculiarity of the quantum motion. [ABSTRACT FROM AUTHOR]