## 3 Results and Discussion  
### ANOVA Analysis  
According to the result of CCD, the threshing cylinder operational performance experiments was performed, and the values of the different response variables were obtained. The results were presented in Table 2. The loss rate (Lr) ranged from 2.495% to 8.231%, while the damage rate (Dr) ranged from 2.634% to 6.114%. These results were consistent with the investigation of the maize ear threshing process [24]. However, both performance parameters cannot be minimized simultaneously at this time. The response variables obtained from the simulations were then analyzed by multiple  
Figure 5: Flowchart of the NSGA-II. quadratic regressions to determine the mathematical models with the best fits. The adequacy and reliability of the regression models were also tested using the analysis of variance (ANOVA). Statistical significance was determined by the ANOVA with quadratic models. The results from ANOVA of the Lr were listed in Table 3. They were evaluated by the coefficient of multiple determination (R\({}^{2}\)). When the value of R\({}^{2}\) was 0.9517, it implied that the quadratic model was not reflected the 0.0483% of total Lr variation. When the F-value was 21.89, it expressed that the regression model of Lr reached great significance for the performance optimization of threshing cylinders. In Tables 3 and 4, single asterisks indicated that the model terms were significant levels (P \(\leq\) 0.05), while double asterisks indicated that the model terms were very significant levels (P \(\leq\) 0.01) and triple asterisks indicated that the model terms were an extremely significant level (P \(\leq\) 0.001). In Table 3, it can be found that significant level terms included the linear terms of Fr, the very significant level terms included the linear terms of Cc and the quadratic terms of (Cc)\({}^{2}\), and the extremely significant level terms included the linear terms of Ds and the quadratic terms of (Ds)\({}^{2}\). Therefore, the most significant term was the linear term, and the interaction term was the least significant for the Lr. In addition, Ds was the strongest factor affecting Lr. These results indicated that the Lr would be improved significantly with the increase of Ds. [PERSON] et al. (2015) also found that the effects of combine cylinder speed on the threshing loss were significant, at a level of 1%. Their results also indicated that the loss rate was improved from 4.7% to 5.28%, with the drum speed increasing from 400 rpm to 500 rpm. The results from ANOVA of the Dr were listed in Table 4. The results were evaluated by the coefficient of multiple determination (R\({}^{2}\)). When the value of R\({}^{2}\) was 0.8768, it implied that the quadratic model was not reflected the 0.1232% of total Dr variation. When the F-value was 7.91, it expressed that the regression model of Dr reached great significance for the performance optimization of the threshing cylinder. In Table 4, it can be found that significant level terms included the linear terms of (Ds)\({}^{2}\), while the very significant level terms included the linear terms of Cc and the extremely significant level terms included the linear terms of Ds. Therefore, the most significant term was the linear term, and the interaction term was the least significant for the Dr. In addition, Ds also was the strongest factor affecting the Dr. The previous research also found that corn kernel damage increased from 10% up to 23%, with rasp bar movement speed varying from 12 to 20 m/s (24).