The present work investigates modal identification of time-varying dynamical systems by exploiting the Hilbert transform. The proposed method, initially based on the Hilbert Vibration Decomposition (HVD) method, first identifies the instantaneous frequencies of the system. Their corresponding components and modal deflection shapes are then extracted from a set of dynamic responses of the system...

introduction: neuro-plasticity is the neuronal system ability to modify and recover itself after the occurrence of impairment and injuries. following the abolition of a sensory modality, modifications will be applied to other modalities and their cortical function in a way that the processing of these modalities not only will happen in their own specific cortical area, but also in those areas t...

The beam propagation method (BPM) used for the design of an integrated optical (IO) coupler was proposed in this paper. A modal of the IO coupler was set up in BeamPROP software that is based on the BPM, and then the modes and the bi-directional propagation in the proposed coupler were investigated. Finally, the structure and dimension of the coupler was determined.

Experimental methods used to determine the dynamic behaviour of helicopter structures can be broadly categorised as either ground testing methods or in-flight testing methods. A major limitation of ground testing is that dynamic properties determined from a grounded helicopter structure are usually significantly influenced by the boundary conditions. Therefore, it is desirable to carry out test...

Vibration-based structural health monitoring (SHM) has become an attractive solution for the global monitoring and evaluation of damage in structures. Numerous damage detection schemes used in vibration-based SHM require knowledge of the modal properties of the structure under evaluation in its current state. The technique of operational modal analysis allows for these modal properties to be ob...

An intermodal switch based on optically induced (through the Kerr effect) periodic coupling in a two-mode waveguide is described and demonstrated. A high-power pump beam injected into the two modes of the waveguide produces a periodic modulation of the refractive-index profile with a period equal to the modal beat length, which causes coupling between the two modes of a simultaneously injected ...

We image spatial distributions of Xeq+ ions in the focus of a laser beam of ultrashort, intense pulses in all three dimensions, with a resolution of approximately 3 microm and approximately 12 microm in the two transverse directions. This allows for studying ionization processes without spatially averaging ion yields. Our in situ ion imaging is also useful to analyze focal intensity profiles an...

in the present paper, we are to put forth a paradigm for the systematic study of modality in persian.with this end in view, we consider modality as a linguistic phenomenon that can be expressed at the level of sentence, at the level of constituents smaller than sentence and/or at the level of discourse. in such a system where sentential modality, sub-sentential modality and discourse modality a...

the dynamic response of the railway under accelerated moving load using dynamic green function is presented in this paper. for this purpose, an exact and direct modeling technique is introduced for the railway modeling as the damped euler-bernoulli beam on the partial winkler foundation with arbitrary boundary conditions subjected to the moving load. the effects of the elastic coefficient of wi...

This paper describes modal testing of a wooden baseball bat with the purpose of finding the peak frequencies and vibration modes and their relation to the so-called “sweet spot”. Initial vibration testing was done by performing a tap test along a Louisville Slugger wooden baseball bat. The bat was suspended by elastic rubber bands to approximate free-free boundary conditions. The peak frequenci...