Nonstationarity detection
Date
2009-02-02T10:53:10Z
Authors
Kiremire, Bunty Byarugaba
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Abstract
This dissertation is an investigation into nonstationarity detection. Current methods
are looked into and a novel method is proposed. An index was developed during
the course of the study called the Stationarity Index. The method of nonstationarity
detection proposed is based on this index and it gives a measure that varies directly
proportionally to changes in the dynamic behavior of the signal. This allows not
only for the detection of nonstationarity but also serves as a means of determining
relatively how much it is changing. The Stationarity Index maps changes in the
dynamics to a range of 0 − 100 in the similar manner to the mapping of measures
to percentages. This allows for the comparison of the variation of dynamics between
separate signals. This ability sets the test apart from current tests. Most
current tests simply determine if nonstationarity is present or not, and do not allow
for the kind of measure that allows relative comparisons between signals. The
index is then used to successfully distinguish between stationary and nonstationary
chaotic signals. It is then used in the analysis of electrocardiogram (ECG) and
electroencephalogram (EEG) profiles. It is able to clearly pick out the changes in
the dynamics that are the result of the onset of partial seizures. It shows potential
for use in the identification of certain dynamic traits in ECG and EEG profiles. Its
ability to discriminate between stationarity and nonstationarity also shows potential
for use in the segmentation of nonstationary biomedical signals into partially (quasi)
stationary segments.