Giant flares from soft gamma-ray repeaters (SGRs) are one of the most violent phenomena in neutron stars. Quasi-periodic oscillations (QPOs) with frequencies ranging from 18 to 1840 Hz have been discovered in the tails of giant flares from two SGRs, and were ascribed to be seismic vibrations or torsional oscillations of magnetars. Here we propose an alternative explanation for the QPOs in terms...

The low frequency vibrations of the ethylamino backbone of six conformers of tryptamine have been studied in the ground and excited states using dispersed fluorescence spectroscopy, rotationally resolved laser induced fluorescence, and ab initio calculations. Four low frequency vibrational modes of the backbone, which involve torsional and librational motions of the ethylamino group, have been ...

The electrical arc furnace (EAF) load is the largest load in power systems. Since electromechanical interactions between electrical loads and turbine-generator are seldom discussed, this paper investigates the torsional vibrations in turbine-generator shafts and blades subject to real and reactive power variations from a large-scale EAF plant. The transient power fluctuation of the load is rand...

This paper describes the Lyapunov-based force control suppressing the coupled bending and torsional vibrations of a one-link flexible arm with a rigid tip body. On the basis of the distributed parameter model, the output feedback control law is constructed using Lyapunov method, and the asymptotic stability of the closedloop system is proved. The proposed controller consists of the PD feedback ...

Terahertz absorption spectra have been recorded for the weakly bound CO2-H2O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H2O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this ...

In this study, rotating flexible shaft-disk system having flexible beams is considered as a dynamic system. After neglecting nonlinear terms, torsional vibration of the shaft-disk system and lateral and longitudinal vibration of the flexible beam are still coupled through the motor speed. The system has three natural frequencies; the flexible shaft-disk system torsional natural frequency, the f...

We report on experimental demonstration of high frequency torsional resonators based on microdisk structures enabled by a “smart-cut” 6H-silicon carbide (6H-SiC) technology. Circular microdisks axially supported by pairs of thin tethers, with diameters of 5–15 lm, exhibit torsional-mode micromechanical resonances with frequency of 1–60 MHz, and quality (Q) factors up to 1280 at room temperature...

Torsional vibrations phenomena are self-excited that occur in the wheelset of railway powertrains due to counter-phase oscillation both wheels. Long-lasting events this type may lead catastrophic failures. Therefore, torsional vibration suppression and mitigation methods have drawn significant attention from industry recent few years. Conventional reduce motor torque once is detected. However, ...

During the drilling process, system devices can be exposed to several types of phenomena incited by lateral, axial, and torsional vibrations. The latter lead severe damages if they are not efficiently controlled quickly mitigated. This research work is focused on vibrations, which stimulated nonlinear dynamical interaction between geological rocks drill bit. Wherein, a model with three degrees ...