# Influencing Factors Analysis and Simulation Calibration of Restitution Coefficient of Rice Grain
## 2 Materials and Methods
### Test Design  
In order to study the influence of various factors on the restitution coefficient of rice grain, the contact materials, rice varieties, spring compressions, and moisture contents were selected to carry out the orthogonal test. Each test was repeated three times, and the average value was taken. The factor level coding table is shown in Table 3.  
\(\mathrm{L_{16}}\) (\(4^{5}\)) orthogonal table was used to design the test scheme. The scheme and results are shown in Table 4, and the analysis of variance is shown in Table 5. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Level** & **Contact Materials** & **Rice Varieties** & **Spring Compressions/mm** & **Moisture Contents/\%** \\ \hline
1 & Rubber plate & Longjing 29 & 50 & 15.12 \\
2 & Q235 steel plate & Wuyudao 4 & 100 & 18.05 \\
3 & Plexiglass plate & Jijing 88 & 150 & 20.84 \\
4 & Seed plate & Shennong 9903 & 200 & 23.90 \\ \hline \hline \end{tabular} Note: The moisture content of rice was the range of suitable harvest period in Northeast China after 1 October.  
\end{table} 
Table 3: Factor level coding table of orthogonal test for restitution coefficient. According to the analysis, the primary and secondary factors affecting the restitution coefficient of rice grain were contact materials, spring compressions, moisture contents, and rice varieties. Among them, the contact materials and spring compressions had an extremely significant effect on the restitution coefficient, and moisture content has a significant effect on the restitution coefficient. In order to explore the influence of different factors on the restitution coefficient of rice grain further, the single factor test was carried out for the significant factors. Among them, rubber plate, Q235 steel plate, plexiglass plate, and seed plate were selected as contact materials. The single factor values of spring compressions were 50 mm, 100 mm, 150 mm, 200 mm, and 250 mm, respectively. The single factor values of moisture content were 15.03%, 17.22%, 18.91%, 21.03%, 22.95%, and 24.94%, respectively. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Order**} & **Contact** & **Rice** & **Spring** & **Moisture** & **Empty Column** & **Restitution** \\  & **Materials(A)** & **Varieties(B)** & **Compressions(C)/mm** & **Contents(D)/\%** & **Compress Column** & **Coefficient** \\ \hline
1 & 1 & 1 & 1 & 1 & 1 & 0.474 \\
2 & 1 & 2 & 2 & 2 & 2 & 0.507 \\
3 & 1 & 3 & 3 & 3 & 3 & 0.509 \\
4 & 1 & 4 & 4 & 4 & 4 & 0.483 \\
5 & 2 & 1 & 2 & 3 & 4 & 0.468 \\
6 & 2 & 2 & 1 & 4 & 3 & 0.476 \\
7 & 2 & 3 & 4 & 1 & 2 & 0.489 \\
8 & 2 & 4 & 3 & 2 & 1 & 0.545 \\
9 & 3 & 1 & 3 & 4 & 2 & 0.497 \\
10 & 3 & 2 & 4 & 3 & 1 & 0.420 \\
11 & 3 & 3 & 1 & 2 & 4 & 0.397 \\
12 & 3 & 4 & 2 & 1 & 3 & 0.460 \\
13 & 4 & 1 & 4 & 2 & 3 & 0.361 \\
14 & 4 & 2 & 3 & 1 & 4 & 0.487 \\
15 & 4 & 3 & 2 & 4 & 1 & 0.394 \\
16 & 4 & 4 & 1 & 3 & 2 & 0.354 \\ \(K_{1}\) & 1.973 & 1.800 & 1.701 & 1.910 & 1.833 & \\ \(K_{2}\) & 1.978 & 1.890 & 1.829 & 1.810 & 1.847 & \\ \(K_{3}\) & 1.774 & 1.789 & 2.038 & 1.751 & 1.806 & \\ \(K_{4}\) & 1.596 & 1.842 & 1.753 & 1.850 & 1.835 & \\ \(k_{1}\) & 0.493 & 0.450 & 0.425 & 0.478 & 0.458 & \\ \(k_{2}\) & 0.495 & 0.473 & 0.457 & 0.453 & 0.462 & \\ \(k_{3}\) & 0.444 & 0.447 & 0.510 & 0.438 & 0.452 & \\ \(k_{4}\) & 0.399 & 0.461 & 0.438 & 0.463 & 0.459 & \\ \(R\) & 0.096 & 0.026 & 0.085 & 0.040 & 0.010 & \\ Factor & & & & & & \\ arrangement & & & & & & \\ \hline \hline \end{tabular} Note: \(K_{1}\)-\(K_{4}\) and \(k_{1}\)-\(k_{4}\) represent the sum and average value of restitution coefficient under each factor and level respectively; \(R\) is the range.  
\end{table} 
Table 4: Orthogonal test scheme and results of restitution coefficient.