Condition monitoring of vehicles with internal combustion engine is of immense importance due to high number of vehicles with such engines and their importance to transport and economy. As many persons use a vehicle which is old and inexpensive, a condition monitoring system designed for such vehicles cannot be expensive. Unfortunately, condition monitoring of engines is usually based on the use of vibration signals, which are acquired by accelerometers. Piezoelectric accelerometers are the most commonly used for this purpose, and such accelerometers are not cheap. However, an alternative exists in the form of microelectromechanical systems (MEMS) accelerometers, which are much cheaper, but have narrower frequency characteristics. This paper describes preliminary results of a research on feasibility of use of MEMS accelerometers for condition monitoring and failure detection in internal combustion engines.
Electrochemical noise is electrochemical technique of growing interest. In the case of random signals obtained by discussed method the power spectral density is one of the fundamental characteristic of process. However its correct estimation imposes stationarity condition on signal under analysis. In the paper the authors present technique for quantitative assessment of degree of non-stationarity for electrochemical noise data by means of theWigner-Ville transform, which enables calculation of local power spectra.
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