Nonlinear oscillators for vibration energy harvesting

Vibration to electricity energy conversion strategies are discussed by using nonlinear stochastic dynamics. General principles for the exploitation of nonlinear oscillators in energy harvesting that provide useful leads for the realization of micropower generators of practical interest are presented

Nonlinear Kinetic Energy Harvesting

Abstract Harvesting of kinetic energy present in the form of random vibrations is an interesting option due to the almost universal presence of this kind of motion. Traditional generators based on piezoelectric effect are built with linear oscillators made by a piezoelectric beam and a mass used to tune the resonance frequency on the predominant frequency of the vibrations spectrum. However, in most cases the ambient random vibrations have their energy distributed over a wide spectrum of frequencies, being rich especially at low frequency. Furthermore frequency tuning is not always possible due to geometrical/dynamical constraints. In this work we present a different method based on the exploitation of the nonlinear dynamical features of bistable oscillator. The experimental results and the digital simulations show that nonlinear harvester (e.g. bistable oscillators) can overcome some of the most severe limitations of generators based on linear dynamics

Chapter Vibration Energy Harvesting: Linear and Nonlinear Oscillator Approaches

Optical physic

Thermal noise limit in the Virgo mirror suspension

Abstract The expected current limit to the Virgo sensitivity is presented. New materials to realize a low thermal noise suspension for the Virgo optics are investigated. A promising fused silica suspension for the Virgo mirrors is presented

A parallel Beowulf-based system for the detection of gravitational waves in interferometric detectors

The detection, in a modern interferometric detector like Virgo, of a gravitational wave signal from a coalescing binary stellar system is an intensive computational task both for the on-line and off-line computer systems. A parallel computing scheme using the Message Passing Interface (MPI) is described. Performance results on a small scale cluster are reported

Low-frequency internal friction in silica glass

Precise low-frequency internal friction measurements on vitreous silica, taken over a wide temperature (4 K160 K the loss angle develops a distinct step-like structure followed by a plateau, both independent of ν, thus signalling the onset of a competing relaxation mechanism with much higher an activation energy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58117/2/epl_80_5_50008.pd

Breaking strength tests on silicon and sapphire bondings for gravitational wave detectors

The realization of third-generation gravitational wave interferometric detectors is under way. An important improvement in detector sensitivity can be obtained with the reduction of thermal noise by reaching a cryogenic stage. Two materials have been identified to perform efficiently at low temperatures: silicon and sapphire. In this work the breaking strength of the silicate bonding that glues cylinders of silicon (Si) and sapphire (Al2O3) has been investigated. All material combinations, flatness quality and orientations have been tested over time. Breaking strength between Si–Si and Si–Al2O3 shows a value similar to that of fused silica, while Al2O3–Al2O3 does not seem to be a promising combination

LISA test mass charging process due to cosmic ray nuclei and electrons

none10noolar energetic particles and galactic cosmic rays with energies larger than 100 MeV cause progressive charging of the LISA experiment test masses. Consequently, Coulomb forces occur between the test masses and the surrounding conducting surfaces generating spurious signals that might be mistaken for gravitational wave signals. We have parametrized the energy spectra of galactic cosmic-ray nuclei and electrons near the LISA orbit in order to evaluate their role in the test-mass charging relative to the most abundant proton component. This work has been carried out using the FLUKA Monte Carlo program.openC. GRIMANI; H. VOCCA; G. BAGNI; L. MARCONI; R. STANGA; F. VETRANO; A. VICERÉ; P. AMICO; L. GAMMAITONI; F. MARCHESONIGrimani, Catia; H., Vocca; G., Bagni; L., Marconi; R., Stanga; Vetrano, Flavio; Vicere', Andrea; P., Amico; L., Gammaitoni; F., Marcheson

Thermal noise reduction for present and future gravitational wave detectors

Thermal noise in mirror suspension is and will be the most severe fundamental limit to the low-frequency sensitivity of interferometric gravitational wave detectors currently under construction. The technical solutions, adopted in the Virgo detector, optimize the current suspension scheme, but new materials and new designs are needed to further reduce the suspension thermal noise. Silicon fibers are promising candidates both for room temperature advanced detectors and for future cryogenic interferometric detectors