# Investigation of a Precise Control Scheme for Rice Quality
## 3 Results and Discussion
### Drying Time  
The drying time was divided into net drying time (Dtn) and total drying time (Dtt). Table 2 shows the different drying times under various conditions, with Dtn ranging from 77.3 to 258.8 min and Dtt ranging from 269.5 to 924 min. Due to tempering, there are significant variations in the Dtt values. According to the ANOVA results presented in Table 3, both Dtn and Dtt model F-values were found to be statistically significant at 51.87 and 40.17, respectively. Additionally, the lack-of-fit values are not significant, indicating that the model is indeed statistically significant. All factors demonstrate a significant impact on the rice sample's net drying time and total drying time (\(p<0.01\)). The F-value indicates the impact of a variable on the response, with a greater value indicating a stronger influence. Based on the F-value, the percentage contributions of each factor to Dtn and Dtt were determined (Figures 2a and 2b, respectively). The order of the factors affecting Dtn and Dtt was found to be consistent: T \(>\) RH \(>\) MC \(>\) TR \(>\) V. Therefore, air temperature, relative humidity, and moisture content are the primary influencing variables for controlling drying time. The impact of tempering on Dtt is less significant than that on Dtn, owing to the tempering effect. Taking into account the tempering stage, the duration of tempering increases proportionally with the ratio. However, it could accelerate the drying process to some extent and affect the overall trend of drying time variation. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & \multicolumn{2}{c}{**Drying Time (Net)**} & \multicolumn{2}{c}{**Drying Time (Total)**} \\ \cline{3-5}
**Source** & **df** & **Sum of Squares** & **F-Value** & **Sum of Squares** & **F-Value** \\ \hline Model & 20 & 87,941.38 & 51.87 ** & 1.02 \(\times\) 10\({}^{6}\) & 40.17 ** \\ T: Temperature & 1 & 27,649.52 & 326.17 ** & 3.75 \(\times\) 10\({}^{5}\) & 296.74 ** \\ RH: Relative air humidity & 1 & 20,578.66 & 242.76 ** & 2.36 \(\times\) 10\({}^{5}\) & 186.31 ** \\ MC: Moisture content & 1 & 18,349.45 & 216.46 ** & 2.09 \(\times\) 10\({}^{5}\) & 165.1 ** \\ V: Air speed & 1 & 4780.03 & 56.39 ** & 56,639.38 & 44.77 ** \\ TR: Tempering ratio & 1 & 10,810.37 & 127.52 ** & 60,791.82 & 48.05 ** \\ T*RH & 1 & 75.03 & 0.89 & 5.87 & 4.64 \(\times\) 10\({}^{-3}\) \\ T*MC & 1 & 1205.41 & 14.22 ** & 16,366.93 & 12.94 ** \\ T*V & 1 & 36.13 & 0.43 & 1522.14 & 1.2 \\ T*TR & 1 & 105.85 & 1.25 & 15,819.76 & 12.51 ** \\ RH*MC & 1 & 57.78 & 0.68 & 308.14 & 0.24 \\ RH*V & 1 & 249.76 & 2.95 & 3467.36 & 2.74 \\ RH*TR & 1 & 1265.05 & 14.92 ** & 3804.1 & 3.01 \\ MC*V & 1 & 41.41 & 0.49 & 100.47 & 0.079 \\ MC*TR & 1 & 114.76 & 1.35 & 509.6 & 0.4 \\ V*TR & 1 & 62.16 & 0.73 & 3166.09 & 2.5 \\ T\({}^{2}\) & 1 & 896.38 & 10.57 ** & 15,360.22 & 12.14 ** \\ RH\({}^{2}\) & 1 & 904.88 & 10.67 ** & 15,395.35 & 12.17 ** \\ MC\({}^{2}\) & 1 & 108.75 & 1.28 & 513.6 & 0.41 \\ V\({}^{2}\) & 1 & 78.06 & 0.92 & 2471.69 & 1.95 \\ TR\({}^{2}\) & 1 & 558.68 & 6.59 ** & 21.85 & 0.017 \\ Residual & 38 & 3221.3 & & 48,072.37 & \\ Lack of Fit & 22 & 2373.58 & 2.04 & 36,175.52 & 2.21 \\ Pure Error & 16 & 847.72 & & 11,896.86 & \\ Cor Total & 58 & 91,162.68 & & \(1.06\times\) 10\({}^{6}\) & \\ \hline \end{tabular} Note: \(p\)-value \(<0.01\) is represented by **.  
\end{table} 
Table 3: Analysis of variance (ANOVA) results of drying time models. For a significance level of 0.05, the interaction terms T*MC and RH*TR, as well as the quadratic terms T\({}^{2}\), RH\({}^{2}\), and TR\({}^{2}\), exhibit significant effects on Dtn; for Dtt, significant effects were observed for T*MC, T*TR, T\({}^{2}\), and RH\({}^{2}\).