Low frequency vibration occurs especially in ground transportation, either as a cause in adjacent environment or within the vehicle itself. The piezoelectric accelerometers commonly used for vibration measurement are not suitable, hence other sensors capable of measuring accelerations down to sub-hertz region have to be used. Based on some previous experience with MEMS acceleration sensors a th...

Nanometer vibration analysis of a target has been demonstrated by a self-aligned optical feedback vibrometry technique that uses a laser-diode-pumped microchip solid-state laser. The laser output waveform, which was modulated through interference between a lasing field and an extremely weak (<- 100-dB) frequency-modulated (FM) feedback field, was analyzed by the Hilbert transformation to yield ...

In the design of the small hermetic compressor, the forces acting on the compressor shell are important parameters to study for noise and vibration control. However, the input forces to the shell cannot be measured directly. In this paper, random force spectra on compressor shell has been measured indirectly with in-situ · vibration responses and system information. Three existing techniques of...

Paper presents a method to measure the dynamic parameters of viscoelastic material bar by the longitudinal vibration testing in a wide frequency range. In the measurement, one end of the bar is driven by a transducer using a pulse wave and the other end is allowed to move freely. The vibration velocity of the free end of the bar is measured by a laser Doppler vibrometer. The dynamic parameters ...

− This paper addresses technical challenges unresolved in the calibration of angular vibration pickups. Primary and/or comparison calibration systems for angular vibration pickups can not be realised without the angular vibration exciter and the precision angular accelerometer suitable for the transfer standard. Recent attempts made to tackle these technical challenges and related achievements ...

Transmission of blast waves is a complex phenomenon and the characteristics vary with blast design parameters and geo-technical properties of medium. Frequency of vibration and triggering component for structural excitation generally quantifies safe vibration magnitude. At closer distance or higher elevations than the blast locations, vertical or transverse component will be the first arrival t...

Continuously monitoring the operation of each individual fan can significantly improve the measurement quality of aerial pollutant emissions from animal buildings that have a large number of fans. To monitor the fan operation by detecting the fan vibration is a relatively new technique. A low-cost electronic vibration sensor was developed and commercialized. However, its large scale application...

BACKGROUND Tissue healing is an intricate process that is regulated by circulation. Heat modalities have been shown to improve skin circulation. Recent research supports that passive vibration increases circulation without risk of burns. Study purpose is to compare and determine effects of short duration vibration, moist heat, and a combination of the two on skin blood flow (SBF) and skin tempe...