Research on the nature of the vibration data collected from helicopter transmissions during flight experiments has led to several crucial observations believed to be responsible for the high rates of false alarms and missed detections in aircraft vibration monitoring systems. This work focuses on one such finding, namely, the need to consider additional sources of information about system vibra...

In order to obtain the useful information from the raw data which contain the state data reflecting the structure condition and the noise, de-noising and feature extraction techniques based on Wavelet analysis were studied. An improved wavelet thresholding algorithm to eliminate the noise for vibration signals was proposed. Comparison analysis with other thresholding algorithms shows that the n...

A novel approach for mode shape feature extraction and model updating of axisymmetric structures based on radial Tchebichef moment (RTM) descriptors is proposed in this study. The features extracted by RTM can effectively compress the full-field modal vibration data retain most important information. reconstruction shapes using accurately describe shapes, simulation shows that function superior...

Growth of Rayleigh-Taylor (R-T) instabilities under the axisymmetric explosion are investigated by two-dimensional hydrodynamical calculations. The degree of the axisymmetric explosion and amplitude of the initial perturbation are varied parametrically to find the most favorable parameter for reproducing the observed line profile of heavy elements. It is found that spherical explosion can not p...

Piping vibration which is mainly caused by the torsional vibration of rotary compressor can be a major noise source of air-conditioner. Especially, the tangential vibration of rotary compressor which is due to the torsional vibration is much higher than the radial vibration or the vertical vibration of compressor. A study as to how the tangential vibration of rotary compressor is related with t...

In this study, the vibration and noise for the cushion frame that directly contacts the driver of the car are investigated. The friction noise from the seat track generating the largest noise is measured and analyzed. Also, vibration measurement and analysis are performed in parallel to locate the position from where the noise is generated. In the next stage, the RPM of motor and the current ch...

Using the fluid-magnetofluid formalism, we obtain axisymmetric stability criteria for a composite disc system consisting of stellar and gaseous magnetized singular isothermal discs (MSIDs). Both (M)SIDs are presumed to be razor-thin and are gravitationally coupled in a self-consistent axisymmetric background equilibrium with power-law surface mass densities and flat rotation curves. The gaseous...

Gears are important element in a variety of industrial applications such as machine tool and gearboxes. An unexpected failure of the gear may cause significant economic losses. For that reason, fault diagnosis in gears has been the subject of intensive research. Vibration signal analysis has been widely used in the fault detection of rotation machinery. The vibration signal of a gearbox carries...

The present paper describes the analytical solutions for the steady boundary layer flow of a Jeffrey fluid over a shrinking sheet. The governing equations of motions are reduced into a set of nonlinear ordinary differential equations by using similarity transformations. Two types of problems, namely, (1) two-dimensional stagnation flow towards a shrinking sheet and (2) axisymmetric stagnation f...