Experiments were conducted in three circulating fluidized beds of 70 mm-i.d. x 2.2 m high, 108 mm-i.d. x 7 m high and 108 mm-i.d. x 5.75 m high (with an expanded top section of 1.5 m high) at ambient condition. The spent fluid cracking catalyst (FCC), glass beads and sand particles were taken as bed materials. The transition velocities U-c and U-k were analyzed by means of traditional statistic analysis and multi-resolution analysis (MRA) of wavelet analysis on the absolute pressure fluctuation (APF) signals acquired at different axial positions in the beds. According to the standard deviation of APF, the effects of axial positions and static bed heights on U-c and U-k were systematically investigated. An appropriate measuring interval of relative axial position was recommended to identify U-k and two correlations calculated by regression of data in literatures and this work were proposed to predict U-c and U-k for absolute pressure measurement. By means of MRA of wavelet analysis, a redefined variable, homogeneous index HI, deduced from the energy of SF and LF subsignals, was successfully applied to determine the U-c and U-k and demarcated the dynamic behaviors of Geldart group A (spent FCC) and group B (sand particles and glass beads) particles in the circulating fluidized beds. (C) 2008 Elsevier Ltd. All rights reserved.