Research Article

Rotor-System Log-Decrement Identification Using Short-Time Fourier-Transform Filter

Table 2

Results of the estimated forward mode parameters at different noise levels with STFT method.

Number = 2 μm = 5 μm = 8 μm
Frequency/HzLog decrementFrequency/HzLog decrementFrequency/HzLog decrement

176.82 ± 0.080.2723 ± 0.003076.93 ± 0.150.2450 ± 0.008776.76 ± 0.330.2684 ± 0.0127
276.97 ± 0.090.2732 ± 0.002976.70 ± 0.140.2732 ± 0.005876.66 ± 0.180.2652 ± 0.0044
376.88 ± 0.170.2658 ± 0.003076.64 ± 0.310.2574 ± 0.010676.79 ± 0.190.2527 ± 0.0069
476.94 ± 0.060.2655 ± 0.003277.01 ± 0.200.2561 ± 0.004077.01 ± 0.240.2451 ± 0.0039
576.86 ± 0.110.2624 ± 0.006777.00 ± 0.190.2762 ± 0.005877.03 ± 0.140.2548 ± 0.0049
676.87 ± 0.120.2607 ± 0.002976.87 ± 0.200.2638 ± 0.004977.11 ± 0.090.2814 ± 0.0022
776.91 ± 0.070.2623 ± 0.001776.77 ± 0.160.2771 ± 0.007377.20 ± 0.190.2961 ± 0.0080
876.98 ± 0.070.2695 ± 0.002176.90 ± 0.190.2656 ± 0.006776.70 ± 0.300.3130 ± 0.0512
976.84 ± 0.060.2567 ± 0.002877.09 ± 0.150.2505 ± 0.003876.76 ± 0.260.2866 ± 0.0110
1076.89 ± 0.080.2670 ± 0.004476.95 ± 0.120.2500 ± 0.002876.58 ± 0.150.2705 ± 0.0091

Note: we set the center frequency to 75 Hz; = 41 Hz, = 50 Hz, = 100 Hz, and = 109 Hz.