Due to the lower tool as the research object to analyze the vibration of the drill string, causes the loss of the low order natural frequency of the drill string and the inherent vibration mode, give rise to the distortion and error of the result from the transient analysis of the drill string. For this purpose, the whole drill string of the deep wells is studied in the article, build the mecha...

This paper discusses the controller design of a PZTactuated suspension dual-stage servo system in hard disk drives. The proposed control structure includes an active vibration damping control loop and a trackfollowing control loop. The vibration damping control loop, which runs at a faster rate than the trackfollowing control loop, utilizes a PZT element on a PZT-actuated suspension as a vibrat...

Engine mount is purposed to control an excessive motion generated from powertrain system and to isolate vibration and noise to be transmitted to main system. As vibration design of engine mount is one of the main items on the phase of vehicle development, the design should be optimized considering various design variables and uncertainties. In the study, design optimization of engine mount for ...

in this paper, concept of cross-bispectrum is used to investigate and model vibration interaction due to nonlinearities in faulted drive shafts in an AH-64 helicopter. Most of the currently available vibration-monitoring tools are built around autoand cross-power spectral analyses which have limited value in detecting frequency correlations higher than first order. Studying higher order correla...

Vibration analysis has been conducted on large rotating machines for many decades. Proximity probes and accelerometers are traditionally used to measure bearing and shaft vibration in an effort to keep mechanical condition in check. Simple measurement of amplitude, to the more complex analysis such as Fast Fourier Transforms, are made by maintenance personnel in an effort to identify the source...

All aircraft vibrate and all components are designed, tested and certified to survive these vibration levels over their entire service life. Design standards such as MIL‐STD‐810F (1) and RTCA DO‐160E (2) are often used to obtain the vibration sign‐ off test; but what is the safety margin on these tests? How many hours do they represent on real aircraft? Can the equipment life b...

In this paper, a low cost 3x3 coupler Mach-Zehnder interferometric optical fibre vibration sensor is proposed. Unlike traditional Mach-Zehnder interferometer with a strain free reference arm, two parallel optical fibres with different strain transfer sensitivity is adopted. With proper demodulation algorithm, the time rate of change of the strain can be computed from the light signal of the out...

For most of vibration signals of civil infrastructures have sparse characteristic, namely, only a few modes contribute to the vibration of the structures. Additionally, the measured vibration data by the sensors placed on different locations of structure almost has same sparse structure in the frequency domain. Based on this group sparsity of the vibration data of structure, the group sparse op...

A curvelet denoising method has been proposed to reduce the time domain noise to improve the detection performance in the distributed fiber vibration sensing system based on phase-sensitive optical time domain reflectometry. The raw Rayleigh backscattering traces are regarded as a gray image and the random noise can be eliminated by the curvelet transform; hence, the amplitude difference induce...