Flowing gel plugging and low-frequency vibration oil extraction technology have been widely applied in low-permeability formation. High probability of overlapping in action spheres of two technologies might lead to poor operating efficiency during gel injection. Study on flowing gel rheological properties under low-frequency vibration was essential, which was carried out indoor with viscosity m...

In this paper, guided wave health monitoring in plate structure for detection of nonlinear contact scatter is conduct using vibration modulation technique. By time-frequency analysis of modulated guided wave series, the nonlinear responses at frequency of vibration are extracted out and used for defect imaging. It is shown that the nonlinear guided wave imaging method based on vibration modulat...

Trial blasting is conducted to identify the characteristics of the blasting of the applicable ground before production blasting and to investigate various problems posed by blasting. The methods and pattern of production blasting are determined based on an analysis of the results of trial blasting. The bedrock in Jeju Island, South Korea is formed through the volcanic activities unlike the inla...

This paper presents a novel piezoelectric vibration energy harvester (PVEH) in which a high-frequency generating beam (HFGB) is driven by an array of low-frequency driving beams (LFDBs) using ropes. Two mechanisms based on frequency upconversion and multimodal harvesting work together to broaden the frequency bandwidth of the proposed vibration energy harvester (VEH). The experimental results s...

We report a demonstration of phase-resolved vibrometry, in which out-of-plane sinusoidal motion is assessed by heterodyne holography. In heterodyne holography, the beam in the reference channel is an optical local oscillator (LO). It is frequency-shifted with respect to the illumination beam to enable frequency conversion within the sensor bandwidth. The proposed scheme introduces a strobe LO, ...

To assess high-level low frequency noise in the working environment, adverse extra-aural effects caused by the noise should be taken into account. The human body vibration induced by low frequency noise, 'noise-induced vibration', was measured on the body surface and the equal-acceleration level contours of the vibration were tentatively estimated. With these contours, we can predict the magnit...

Human health and comfort under whole-body vibration depend on the level, frequency, direction, location, and duration of the acceleration. The international standard ISO 2631-1 [1] specifies a method of evaluation of the effect of exposure to vibration on humans by weighting the root-mean square (r.m.s.) acceleration with human vibration sensitivity curves. There are six frequency-weighting cur...

The mean vibration transmissibility values were measured for cotton work gloves commonly used in vibration-generating workplaces to evaluate the vibration isolating performance of cotton work gloves. The mean vibration transmissibility values of work cotton gloves were compared with those of four types of anti-vibration gloves measured in the same way. All the measurements were performed based ...

BACKGROUND Besides noise, mechanical vibration of a general effect (whole body vibration), is an important physical risk factor that occurrs in the farmers' work environment. The vibration occurs on the seats of agricultural vehicles in motion, during the performance of specified field and transportation work tasks. MATERIAL AND METHOD The study covered the measurements of time schedules of a...