Faculty Publications

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    Improved phase estimation based on complete bispectrum and modified group delay
    (2008) Narasimhan, S.V.; Basumallick, N.; Chaitanya, R.
    In this paper, a new method for extracting the system phase from the bispectrum of the system output has been proposed. This is based on the complete bispectral data computed in the frequency domain and modified group delay. The frequency domain bispectrum computation improves the frequency resolution and the modified group delay reduces the variance preserving the frequency resolution. The use of full bispectral data also reduces the variance as it is used for averaging. For the proposed method at a signal to noise ratio of 5dB, the reduction in root mean square error is in the range of 1.5-7 times over the other methods considered. © 2008 Springer-Verlag London Limited.
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    A novel procedure for determination of hydrodynamic pressure along upstream face of dams due to earthquakes
    (2010) Gogoi, I.; Maity, D.
    The estimation of hydrodynamic pressures along the upstream face of the dam is a critical parameter for the accurate analysis and design of a dam. The accurate estimation of the hydrodynamic pressures necessitates the consideration of interaction between the dam, the reservoir and the foundation. The interaction effects of the unbounded domain of the reservoir and the absorptive materials deposited at the reservoir bottom are frequency dependent which can be incorporated in a frequency domain procedure easily. But in a time domain procedure the frequency dependent interaction effects are lost. In a frequency domain solution, the excitation frequencies are extracted from the earthquake signal using a Fourier transformation, but do not give any information about how it varies with time. To overcome this, a short-time Fourier transform based formulation is presented in this paper to evaluate the hydrodynamic pressures in time domain to account for the frequency dependent interaction effects of the dam-reservoir system. Thus, the adequate accuracy in the determination of hydrodynamic pressure under earthquake excitation is ensured with the proposed truncation boundary condition. © 2010 Elsevier Ltd. All rights reserved.
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    Fault Detection of Gear Using Spectrum and Cepstrum Analysis
    (Springer Nature, 2015) Vernekar, K.; Kumar, H.; Gangadharan, K.V.
    This paper presents an experimental investigation on damage detection of internal combustion (IC) engine gear box using conventional vibration spectrum and cepstrum analysis. Experiment was carried out on two stroke internal combustion engine gearbox without considering the combustion. Vibration signals were collected for healthy as well as defective gear condition. The signals were analysed in time domain, frequency domain and cepstrum plots for fault detection. An experimental result demonstrates the dynamic behaviour in frequency domain, which is dominated by gear mesh frequency (GMF) and its harmonics.Based on the experimental results obtained, spectrum and cepstrum analysis can be effectively used for fault prediction of machine components. © Printed in India.