A novel wireless and passive surface acoustic wave (SAW) based temperature-compensated vibration sensor utilizing a flexible Y-cut quartz cantilever beam with a relatively substantial proof mass and two one-port resonators is developed. One resonator acts as the sensing device adjacent to the clamped end for maximum strain sensitivity, and the other one is used as the reference located on clamp...

The vibration based signal processing technique is one of the principal tools for diagnosing faults of rotating machinery. Empirical mode decomposition (EMD), as a time-frequency analysis technique, has been widely used to process vibration signals of rotating machinery. But it has the shortcoming of mode mixing in decomposing signals. To overcome this shortcoming, ensemble empirical mode decom...

In this paper we present a simple, yet powerful, method for the identification of stiffness matrices of structural and mechanical systems from information about some of their measured natural frequencies and corresponding mode shapes of vibration. The method is computationally efficient and is shown to perform remarkably well in the presence of measurement errors in the mode shapes of vibration...

A discrete-time sliding mode control design for a ball-screw driven positioning table is presented. The basic feature of this design is that high speed and high positioning accuracy can be met despite of the fact that the controlled process suffers from friction and mechanical flexibility. Disturbance rejection, in the form of friction compensation and vibration suppression, is the main focus o...

A procedure for obtaining robust time-optimal command profiles for multi-mode flexible spacecraft is presented. The command profiles are required to move a spacecraft from rest-to-rest with zero residual vibration. Furthermore, the commands are subject to a robustness constraint in an attempt to keep the residual vibration at a low level in the presence of modeling errors. The robustness constr...

In order to meet the requirements of cable fault detection, a new structure of piezoelectric accelerometer was designed and analyzed in detail. The structure was composed of a seismic mass, two sensitive beams, and two added beams. Then, simulations including the maximum stress, natural frequency, and output voltage were carried out. Moreover, comparisons with traditional structures of piezoele...

Using Scanning Probe Acoustic Microscopy (SPAM), we characterize the surface and subsurface topography of a nano HfO2 film on SiO2 substrate quantitatively. Surface topography shows that the roughness of the film’s surface is less than 3 nm, while the acoustic image of Sample Vibration Mode (SVM) shows that there are dozens of random lines at the film’s subsurface, which might be scratches from...

With advances in sensor technology and availability of low cost integrated circuits, a wireless monitoring sensor network has been considered to be the new generation technology for structural health monitoring. Wireless Intelligent Sensor and Actuator Network (WISAN) has hence been developed as a vibration based structural monitoring network that allows extraction of mode shapes from output-on...

An immersed-boundary method based flow solver coupled with a finite-element solid dynamics solver is employed in order to conduct direct-numerical simulations of phonatory dynamics in a three-dimensional model of the human larynx. The computed features of the glottal flow including mean and peak flow rates, and the open and skewness quotients are found to be within the normal physiological rang...

This paper presents chaotic behavior of a nonlinear viscoelastic beam under a moving mass interaction. Considering the stretching effect which is modeled by the Lagrangian strain theory and using linear Kelvin-Voigt model to constitute viscoelastic behavior of the beam, the governing equations of transverse vibration is derived. Then Galerkin truncation is applied to find the ordinary different...