Amplitude Of Vibration Signal Research Articles

An advanced method for determination of loss of coolant accident in nuclear power plants

A major objective in reactor design is to provide the capability to withstand a wide range of postulated events without exceeding specified safety limits. Assessment of the consequence of hypothetical loss of coolant accident (LOCA) in primary circuit is an essential element to address fulfilment of acceptance criteria. In addition, finding the position of rupture, one could manage accident in a right direction. In this work, the transient vibration signal from a pipe rupture is used to determine the position of LOCA. A finite element formulation (Galerkin Method) is implemented to include the effect of fluid-structure interaction (FSI). The coupled equations of fluid motion and pipe displacement are solved. The obtained results are in good agreement with published data. Fast Fourier transform (FFT) provides an alternate way of representing data. Instead of representing vibration signal amplitude as a function of time, the signal is represented by the amount of information, which is contained at different frequencies. The most of frequencies of structure and fluid coupled are presented in the FFT of structural response and through it the dominant frequency of excitation is obtained. Furthermore, the power spectral density (PSD), a measurement of energy at various frequencies is worked out. MATLAB software is used to convert signals from the time to frequency domain and to obtain PSD of signals.

Faulted gear identification of a rotating machinery based on wavelet transform and artificial neural network

In this paper, a condition monitoring and faults identification technique for rotating machineries using wavelet transform and artificial neural network is described. Most of the conventional techniques for condition monitoring and fault diagnosis in rotating machinery are based chiefly on analyzing the difference of vibration signal amplitude in the time domain or frequency spectrum. Unfortunately, in some applications, the vibration signal may not be available and the performance is limited. However, the sound emission signal serves as a promising alternative to the fault diagnosis system. In the present study, the sound emission of gear-set is used to evaluate the proposed fault diagnosis technique. In the experimental work, a continuous wavelet transform technique combined with a feature selection of energy spectrum is proposed for analyzing fault signals in a gear-set platform. The artificial neural network techniques both using probability neural network and conventional back-propagation network are compared in the system. The experimental results pointed out the sound emission can be used to monitor the condition of the gear-set platform and the proposed system achieved a fault recognition rate of 98% in the experimental gear-set platform.

Enhanced detection of vibration

A device detects an emission source of a vibration signal against a background of noise, where the vibration signal is produced by a mechanical system and has one or more frequency components. A sensor senses the vibration signal and produces a sensor signal corresponding to the vibration signal. The sensor has a mechanical frequency selection structure for mechanically resonating at desired frequencies and for mechanically attenuating a frequency component of the vibration signal having a frequency outside the desired frequencies. The mechanical frequency selection structure thus produces a mechanically-tuned sensor signal. Electrical frequency selection filters electrically attenuate a frequency component of the mechanically-tuned sensor signal having a frequency outside the desired frequencies. The electrical frequency selection filters thus produce an electrically-tuned sensor signal. The device has at least one amplifier with gain for producing an amplified signal corresponding to the electrically-tuned sensor signal. An amplitude characteristic determination circuit determines an amplitude characteristic corresponding to the vibration signal's amplitude. The amplitude characteristic determination circuit also generates an amplitude indication based on the amplitude characteristic. The amplitude indication and adjusts the gain of the amplifier based at least in part on the amplitude indication.