In this paper, we experimentally demonstrate non-degenerate parametric resonance in a torsional micro electro mechanical (MEM) oscillator with two interacting mechanical modes of oscillation. The parametric oscillation results from a displacement-dependent electrostatic force generated in both the modes of oscillation. There is a decoupling of the input and the output frequencies in this mode o...

A novel microresonator operating on the principle of nonlinear modal interactions due to autoparametric 1:2 internal resonance is introduced. Specifically, an electrostatically actuated pedal-microresonator design, utilizing internal resonance between an out-of-plane torsional mode and a flexural in-plane vibrating mode is considered. The two modes have their natural frequencies in 1:2 ratio, a...

Methods are developed for study of isotropic cubes via resonant ultrasound spectroscopy. To that end, mode structure maps are determined for freely vibrating isotropic cubes via finite element method over the full range of Poisson's ratio ν (-1 to +0.5). The fundamental torsional mode has the lowest frequency provided ν is between about -0.31 and +0.5. Experimental measurements for the mode str...

Experimental Raman and IR spectra of multiferroic [(CH3)2NH2][Ni(HCOO)3] were recorded at room temperature. The three-parameter hybrid B3LYP density functional method has been used with the 6-31G(d, p) basis set to derive the equilibrium geometry, atomic spin densities, vibrational wavenumbers, infrared intensities and Raman scattering activities. Based on these calculations, the assignment of ...

Far-infrared-absorption spectroscopy has been used to study the low-frequency (<or=100 cm-1) intermolecular modes of methanol in mixtures with water. With the aid of a first-principles molecular-dynamics simulation on an equivalent system, a detailed understanding about the origin of the low-frequency IR modes has been established. The total dipole spectrum from the simulation suggests that the...

High-voltage direct current (HVDC) lines with line-commutated converter (LCC) are being increasingly employed to transmit bulk wind power over long distance. However, this may cause the sub-synchronous torsional interaction (SSTI) between the wind farms and the LCC-HVDC system. The SSTI characteristics of wind farms with fixed-speed induction generator (FSIG) wind turbines connected to LCC-HVDC...

Recognition of cell-surface sialyldisaccharides by influenza A hemagglutinin (HA) triggers the infection process of influenza. The changes in glycosidic torsional linkage and the receptor conformations may alter the binding specificity of HAs to the sialylglycans. In this study, 10-ns molecular dynamics simulations were carried out to examine the structural and dynamic behavior of the HAs bound...

Increasing evidence is becoming available about not only the surface differential rotation of rapidly rotating cool stars but, in a small number of cases, also about temporal variations, which possibly are analogous to the solar torsional oscillations. Given the present difficulties in resolving the precise nature of such variations, due to both the short length and poor resolution of the avail...