In this paper, the pressure fluctuation signal in a gas-solid fluidized bed is modeled as the addition of teo independent components: fractal Brownian motion (FBM) and Guassian white noise (GWN). With a robust algorithm based on orthonormal wavlet transform, the self-similarity parameter H of FBM and the intensity parameter sigma_w of GWN in the model are accurately estimated. The changes of H and sigma_2 with different gas velocity are studied and an effort is made to interpret the trends. A quantitative evidence is provided which well demonstrates that the FBM component dominates the pressure fluctuation signla while the GWN part is minor. Also, the resutls indicates that the jet flow and formation of small bubbles is an important GWN source.
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