Continuous Cross Machine Formation by Wavelet Transform Analysis, 19PaperCon
A position sensitive spectral analysis of the grammage distribution using a continuous wavelet transform (CWT) was performed on production QCS data sets. Sequential analysis of cross machine (CD) profiles obtained from scanning sensors was transformed into three-dimensional data sets that show size distribution and relative intensity of grammage flocs as a function of CD position. The analytical method uses a non-orthogonal, one-dimensional CWT with a Marr basis wavelet to detect extrema within the data set. Coupled with data reduction techniques that minimize the effect of discrete features by assuming a fixed statistically stationary window in the machine direction (MD) of the data stream, samples were analyzed to determine the variability that exists in the CD as a function of time. The static and stochastic components of the CWT were separated to quantify MD persistent grammage streaks and formation streaks, respectively, within the fixed MD window. A simple routine was used to simulate streaming QCS data into a buffer for analysis that continually changes as the fixed sampling window is advanced in the MD direction. 3-D Spec-tral plots were generated to study changes in grammage streaks and formation streaks with time for the actual machine generated data. The utility of the combined methods for application in the assessment and control of paper structural properties is presented.
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Continuous Cross Machine Formation by Wavelet Transform Analysis, 19PaperCon
