## 2 Materials and Methods
### Main Objectives of the Experiments  
The methodology for determining the quality indices of the calibration process is as follows:  
* defining the quality indices;
* experimental setup (setting the controlled experiments using the cylindrical calibrator described above, setting the number of experiments--3 repetitions for each hybrid used);
* data collection (data were collected for various parameters during experiments);
* Data analysis and calculation (the data obtained were analyzed, and calculations were made in order to obtain the results);
* Results analysis (results were analyzed and interpreted).  
Experiments conducted for the three corn hybrids aimed at the following:  
* determining the contact point of the seeds with the cylindrical sieve--using a cylindrical sieve with a diameter of 630 mm; the angle of inclination of the inclined plane was varied so that \(\theta\) took values between 45 and 60 degrees when the difference between the tangential and peripheral speed was as large as possible.
* the influence of the length of the calibration cylinder as a function of speed--11 distinct revolutions were tested, obtained by using several spare chain wheels, and the seeds were introduced into the calibration cylinder and separated using the cylindrical sieve with 5 mm \(\times\) 25 mm elongated orifices. The fractions that passed through the sieve were evacuated through the 9 funnels (fitted on the calibrating equipment only for experiments; in the case of use in production, three funnels were joined and collected the material from one segment of the sieve each) numbered from 1 to 9 and collected in special trays for each sieve segment of approximately 220 mm active length. The discharge funnel at the end of the calibration cylinder was marked with no. 10, and it collected the refusal from the calibration process. The results were recorded and processed for each individual hybrid.
* the influence of speed on the separation process--in the same working conditions with 11 revolution speeds, the seeds evacuated through the 10 funnels were collected  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Crt. No** & \(\theta\) & \(X_{p}\) & \(Y_{p}\) & \
\begin{tabular}{c} **Crt.** \\ **No.** \\ \end{tabular} & \(\theta\) & \(X_{p}\) & \(Y_{p}\) &
\begin{tabular}{c} **Crt.** \\ **No.** \\ \end{tabular} & \(\theta\) & \(X_{p}\) & \(Y_{p}\) \\ \hline
3 & 47 & 0.428 & \(-\)0.460 & 10 & 54 & 0.352 & \(-\)0.485 & 17 & 61 & 0.259 & \(-\)0.467 \\
4 & 48 & 0.419 & \(-\)0.466 & 11 & 55 & 0.339 & \(-\)0.485 & 18 & 62 & 0.245 & \(-\)0.461 \\
5 & 48 & 0.409 & \(-\)0.471 & 12 & 56 & 0.327 & \(-\)0.484 & 19 & 63 & 0.232 & \(-\)0.454 \\
6 & 50 & 0.399 & \(-\)0.475 & 13 & 57 & 0.313 & \(-\)0.483 & 20 & 64 & 0.218 & \(-\)0.446 \\
7 & 51 & 0.388 & \(-\)0.479 & 14 & 58 & 0.300 & \(-\)0.480 & 21 & 65 & 0.204 & \(-\)0.437 \\ \hline \hline \end{tabular}
\end{table}
Table 3: _Cont._in trays; the seeds in each tray were counted, for each rotation separately, and the results obtained were recorded.  
To determine the specific distribution curves, for each individual hybrid, we determined the following:  
* number of classes, \(n\) [-];
* class interval, \(\lambda\), [-];
* \(T_{s}\), the total number of seeds of a sample (the sum of the seeds of all cobs of a hybrid) [-];
* the average size of a dimension, \(M_{c}=S_{nl}/T_{s}\), [mm], where \(S_{nl}\) is the sum of all dimensions;
* root mean square deviation for thickness \(\sigma_{c}\), [-].