Spectrum Analysis Of Non-uniformly Sampling Signal Of Track Irregularities

The track irregularities, comprising the vertical profile, the cross-level, the alignment and the gage irregularity, being the vibration exciter of the wheel-rail system, could bring about instability, discomfort as well as the kinetic action to wreck the railway and the train. It's important to study the property of the track irregularities.Currently, the spectrum analysis for the track irregularities is based on the sampling data at a uniform time interval. The precondition is the train running at a constant speed. But under the influence of some uncertain factors, the train couldn't run at a constant speed, which results in the non-uniform time intervals between the consecutive sampling data. Overleaping the influence of the non-uniform sampling could lead to distorted consequence.This paper studies the spectrum analysis of the non-uniformly sampling signal of the track irregularities. The main research is as follows:1. Plentiful test showed that the track irregularities were random processes varying with the traffic mileage. In general, the track irregularities were regarded as the stationary ergodic random processes. In this thesis, the property of the non-uniformly sampling signal of the stationary ergodic random processes of the track irregularities was studied.2. Some excellent papers about the non-uniformly sampling signal analysis were summarized. These theories, such as the Fourier Analysis Method, the Sequence De-compound Method and the Signal Reconstitute Method, didn't adapt to analyze the non-uniformly sampling signal of the track irregularities.3. A new method, the sampling interval stat. analysis method, was set up to analyze the non-uniformly sampling signal of the wide-sense stationary random processes. In the new method, the probability density function of the sampling time intervals was used for describing the statistical features of the non-uniformly sampling signal in the time field and the frequency field.4. The new method was applied to analyze the uniformly sampling signal as well as some non-uniformly sampling cases. This thesis drew a conclusion in accordance with the classical conclusion, which verified the new method correct and reasonable.5. The new method was applied to analyze the track irregularities. The results showed that the new method was a significant development over the tradition spectrum analysis theory.6. Another new method, the phase-lock and multiple-frequency method, was provided to improve the hardware instrument to eliminate the influence of non-uniformly sampling.