## 3 Results and Discussion
### Correlations Between Damage Index and Impact Parameters
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Characteristic**} & \multirow{2}{*}{**Surface**} & \multicolumn{2}{c}{**Impact Velocity, \(v\)**} & \multicolumn{2}{c}{**Peak Acceleration, \(a\)**} & \multicolumn{2}{c}{**Change in Velocity, \(\Delta v\)**} & \multicolumn{2}{c}{**D Damage Index, \(\Delta v\)**} \\  & & **Velocity, \(v\)** & **Acceleration, \(a\)** & **Velocity, \(\Delta v\)** & \(DI\) & \(a\times\Delta v\) \\ \hline \multicolumn{8}{c}{Saturna Variety} \\ \hline Impact velocity, \(v\) & Concrete & 1 & & & & \\ Peak acceleration, \(a\) & Concrete & 0.8064 & 1 & & & \\ Change in velocity, & & & & & \\ \(\Delta v\) & Concrete & 0.7938 & 0.7534 & 1 & & \\ Damage Index, \(DI\) & Concrete & 0.5944 & 0.5412 & 0.5322 & 1 & \\ \(a\times\Delta v\) & Concrete & 0.8415 & 0.9165 & 0.9474 & 0.5518 & 1 \\ Impact velocity, \(v\) & Rod & 1 & & & & \\ Peak acceleration, \(a\) & Rod & 0.8387 & 1 & & & \\ Change in velocity, & Rod & 0.6240 & 0.6632 & 1 & & \\ \(\Delta v\) & \multirow{2}{*}{Damage Index, \(DI\)} & Rod & 0.8466 & 0.7758 & 0.5007 & 1 & \\ \(a\times\Delta v\) & Rod & 0.7667 & 0.9074 & 0.8928 & 0.6633 & 1 \\ Impact velocity, \(v\) & Steel & 1 & & & & \\ Peak acceleration, \(a\) & Steel & 0.8069 & 1 & & & \\ Change in velocity, & & Steel & 0.8598 & 0.7456 & 1 & & \\ \(\Delta v\) & Steel & 0.9020 & 0.7943 & 0.8046 & 1 & \\ \(a\times\Delta v\) & Steel & 0.8785 & 0.9343 & 0.9247 & 0.8325 & 1 \\ Impact velocity, \(v\) & Bulk potatoes & 1 & & & & \\ Peak acceleration, \(a\) & Bulk potatoes & 0.6653 & 1 & & & \\ Change in velocity, & & & & & & \\ Damage Index, \(DI\) & Bulk potatoes & 0.2047 & \(-\)0.0206 & 0.1841 & 1 & \\ \(a\times\Delta v\) & Bulk potatoes & 0.8336 & 0.8993 & 0.8424 & 0.0854 & 1 \\ \hline \multicolumn{8}{c}{Hermes Variety} \\ \hline Impact velocity, \(v\) & Concrete & 1 & & & & \\ Peak acceleration, \(a\) & Concrete & 0.7806 & 1 & & & \\ Change in velocity, & & Concrete & 0.7836 & 0.7521 & 1 & & \\ \(\Delta v\) & Concrete & 0.4147 & 0.5402 & 0.4206 & 1 & \\ Damage Index, \(DI\) & Concrete & 0.8240 & 0.9134 & 0.9481 & 0.4817 & 1 \\ \(a\times\Delta v\) & Concrete & 0.8240 & 0.9134 & 0.9481 & 0.4817 & 1 \\ Impact velocity, \(v\) & Rod & 1 & & & & \\ Peak acceleration, \(a\) & Rod & 0.8103 & 1 & & & \\ Change in velocity, & & & & & & \\ Change in velocity, & & & & & & \\ Change in velocity, & & & & & & \\ Change in velocity, & & & & & & \\ \(\Delta v\) & Steel & 0.8702 & 0.7337 & 1 & & \\ DamageBulk potatoes had relatively the lowest values of \(\lambda_{m}\) coefficients, especially for the Saturna variety (0.0057). The highest values of \(\lambda_{m}\) coefficients were obtained for tuber impacts with a rod conveyor. For the Saturna and Hermes varieties, the values of this coefficient were 0.0282 and 0.0415, respectively. The higher the value of the \(\lambda_{m}\) coefficient, the greater the probability of damage to potato tubers from the surface. The values of the root mean square error (RMSE) and coefficients of determination (R\({}^{2}\)) given in Table 6 were used to assess the accuracy of the developed model. The RMSE error for the Saturna variety was relatively low for the steel (10.91%) and concrete (12.58%) surfaces, indicating that the model is accurate for these bases. For the Hermes variety, the RMSE error was higher for all surfaces than that of the Saturna variety. For the steel surface, the RMSE was 13.41% and that for the concrete was 15.33%, suggesting that the Hermes variety model has a slightly larger error. However, the more significant RMSE errors for this variety may not be due to model errors but to the larger values of the damage index that the model is trying to predict. The model predicts the damage less accurately for the rods, achieving higher errors (19.72% for the Hermes variety and 13.23% for Saturna variety). These may be due to the greater variability in terms of the damage, as demonstrated by the lower R\({}^{2}\).