## 3 Numerical Simulations and Discussion
### Finding of Adjustment Point  
#### 3.2.1 Results  
The First Kind of Simulation Based on Algorithm I  
Using the points in Table 1 as the last measuring points, respectively, eight kinds of simulations are conducted, and then Equations (19)-(22) are obtained using the computational example g4.4. They represent the biggest relative error of the identified main stiffness and damping coefficients of each bearing. The nodes, where the bearings and discs are located, are used as the m + n measuring points in these simulations. In Equations (19)-(22), the elements in a row of the matrix are the maximum identification errors of bearing coefficients of #1-#8 bearings, respectively, when using the same point as the last measuring point. For the elements in a column, they are the maximum identification errors of bearing coefficients of the same bearing when the measuring points #14, #29, #33, #49, #53, #69, #73 and #91 are applied, respectively. According to Equations (19)-(22), the results are the following. \begin{table}
\begin{tabular}{c c c c c c c} \hline \#14 & \#29 & \#33 & \#49 & \#53 & \#69 & \#73 & \#91 \\ \hline \end{tabular}
\end{table} 
Table 1: The last measuring point. Figure 3: Four-span four-disc rotor supported by oil-journal bearings (h4.4). (1) #14 point as the last measuring point. When #14 point, which is near #1 bearing, is used, the maximum identification error of bearing coefficients of #1 disc is the smallest among those of the eight bearings. The maximum identification errors of k1.xx and k1.yy are 5.75 \(\times\) 10\({}^{-7}\)%, and 9.74 \(\times\) 10\({}^{-8}\)%, respectively. They are almost equal to zero. Moreover, the maximum relative errors of c1.xx and c1.yy are also almost equal to zero; although, they are bigger than that of k1.xx and k1.yy. They are only 0.0882  
(5) #53 point as the last measuring point. When #53 point, which is near #5 bearing, is used, the identification error of #5 bearing coefficients is the smallest among the eight bearings. The maximum relative errors of k5.xx and k5.yy, which are only 5.03 \(\times\) 10\({}^{-5}\)% and 2.16 \(\times\) 10\({}^{-5}\)%, respectively, almost equal zero. Moreover, the maximum relative errors of c5.xx and c5.yy are also almost equal to zero; although, they are bigger than that of k5.xx and k5.yy. They are only 1.60% and 3.52%, respectively. However, the identification error becomes bigger for some other bearings. For the main stiffness coefficient in the x direction, the biggest of the eight maximum errors occurs at #6 bearing. For the main stiffness coefficient in the y direction, the biggest of the maximum errors occurs at #2 bearing. For the main damping coefficients in the x and y directions, they are at #1 bearing and are 512% and 420%, respectively. (6) #69 point as the last measuring point. When #69 point, which is near #6 bearing, is used, the identification error of #6 bearing coefficients is very small; although, it is not the smallest among the eight bearings. The maximum relative errors of k6.xx and k6.yy, which are only 8.03 \(\times\) 10\({}^{-6}\)% and 8.19 \(\times\) 10\({}^{-6}\)%, respectively, almost equal zero. Moreover, the maximum relative errors of c6.xx and c6.yy are also almost equal to zero; although, they are bigger than that of k6.xx and k6.yy. They are only 0.332% and 0.540%, respectively. However, the identification error becomes bigger for some other bearings. For the main stiffness and damping coefficients in the x and y directions, the biggest values of the eight maximum errors occur at #1 bearing. For the main damping coefficients in the x and y directions, they are at #1 bearing and are 5169% and 2235%, respectively. (7) #73 point as the last measuring point. When #73 point, which is near #7 bearing, is used, the identification error of #7 bearing coefficients is very small; although, it is not the smallest among the eight bearings. The maximum relative errors of k7.xx and k7.yy, which are only 5.28 \(\times\) 10\({}^{-6}\)% and 7.84 \(\times\) 10\({}^{-6}\)%, respectively, almost equal zero.