– In a magnetic fluid parametrically driven surface waves can be excited by an external oscillating magnetic field. A static magnetic field changes the restoring forces and damping coefficients of the various surface waves. This property enables the excitation of both subharmonic and harmonic responses of the standing waves. Introduction. – " Most fluids, if not all, may be used to produce thes...

Parametric resonance is a type of nonlinear vibration phenomenon [1], [2] induced from the periodic modulation of at least one of the system parameters and has the potential to exhibit interesting higher order nonlinear behaviour [3]. Parametrically excited vibration energy harvesters have been previously shown to enhance both the power amplitude [4] and the frequency bandwidth [5] when compare...

Parametric instability of a standing gravity–capillary wave is observed in conditions irradiation surface liquid by plane ultrasound beam modulated amplitude. A threshold value intensity for excitation the parametric oscillations determined, and frequency response process measured. mechanism based on sound radiation pressure applied to curved with menisci suggested.

The paper presents a fast impedance spectroscopy method for objects with very high impedance |Zx|≥1GΩ modeled by multi-element two-terminal RC networks. The method is based on analysis of the object response in the time domain after square pulse excitation. The object impedance spectrum was obtained using continuous Fourier transform. Simulation tests were performed for different excitation pul...