A vibration-driven electret generator has been developed for energy harvesting applications. By using parylene as the spring material, a low-resonant-frequency MEMS generator is realized. Large inplane amplitude of 0.8 mm at the resonant frequency as low as 37 Hz has been achieved. With our early prototype, output power of 0.28 μW has been obtained. We also demonstrate electret-powered operatio...

Hysteresis-induced drift is a major issue in the detection of force induced during grinding and cutting operations. In this letter, we propose an external estimation method based on Mel spectrogram obtained from sensor. We focus frequent strong correlation between vibration frequency operations with periodic vibrations. The information found to be more effective for accurate than amplitude case...

The results of experiments on the threshold behavior and large-amplitude oscillation of "outward-swinging door" vibrating flap valves in an air environment are reported and compared with the predictions of a simple nonlinear theory that parametrizes aerodynamic effects by means of a simple damping coefficient together with a contraction coefficient for the flow. The agreement is acceptably good...

In this paper, a new viscoelastic size-depended model developed based on a modified couple stress theory and the for nonlinear viscoelastic material in order to vibration analysis of a viscoelastic nanoplate. The material of the nanoplate is assumed to obey the Leaderman nonlinear constitutive relation and the von Kármán plate theory is employed to model the system. The viscous parts of the clas...

A MEMS vibration-driven electret generator for energy harvesting has been developed. Parylene high-aspect-ratio flexible spring is employed to support the seismic mass with high-performance patterned electret. The seismic structure enables large in-plane oscillation amplitude of 1 mm and low resonant frequency of 37Hz. With our early prototype, we have obtained 21 Vp-p voltage output, correspon...

Orthopaedic rehabilitation of osteoporosis by muscle vibration exercise is investigated theoretically using Wolff's theory of strain-induced bone 'remodelling'. The remodelling equation for finite amplitude vibration to be transmitted to the bone via muscle corresponds to a slowly time-varying non-linear dynamic system. This slowly time-varying system is governed by a Riccatti equation with rap...

We study nanomechanical resonators with frequency fluctuations due to diffusion of absorbed particles. The diffusion depends on the vibration amplitude through inertial effect. We find that, if the diffusion coefficient D is sufficiently large, the resonator response to periodic driving displays bistability. The lifetime of the coexisting vibrational states exponentially increases with increasi...

OBJECTIVES A three-dimensional finite element (FE) model of the lumbar spine L3-L5 segment, the ligaments of which were assumed to be nonlinear materials, was established based on the actual vertebra geometry to investigate the influence of the injury lumbar spine on its adjacent components on the condition of whole-body vibration. Several injury conditions of the spine components were assumed,...