Figure 5 Example of noise sensitivity. Sensitivity of estimate of 2nd mode to noise on accelerometers 1 and 3 and rotation rate sensor 3. Dashed vertical line indicates likely natural frequency of 2nd mode.
Figure 6 Example of how an estimate is composed: Relative contributions from acceleration measurements 1 and 3 plus rotation rate 3 to the estimate of Mode 1. Vertical line indicates expected 1st natural frequency.
Figure 7 "Leak" from modes 5, 6 and 7 to estimate of 1st modal weight. Dashed vertical lines indicate likely natural frequencies for modes 5, 6 and 7
Figure 8 Time traces and amplitude spectra of estimated riser displacement at the locations of the instrument containers.
Figure 9 Time traces and amplitude spectra of estimated modal weights.
Figure 10 Estimated rms-profile of riser. Dotted curve shows result when gravitational influence on accelerometers is neglected.
