The selected shapes of the blades are: smooth-edge triangular, serrated-edge triangular
and rectangular serrated-edge. Each blade is fixed on the disc by two bolts.
Considering the number of variables and their levels, Taguchi L9 orthogonal arrays
table was used. Considering a normal statistical method for these design 81 tests must
be conducted, but using the Taguchi method the design reduces to 9 tests. According to
the Taguchi proposed table, the test were carried out in the field. 3 stems in each
treatment were randomly selected and photographed (3 replications). The images were
imported to image processing software. The software calculates an eigenvalue for each
treatment and replication. It is called the eigenvalue of good pixels. These are unitless
numbers and are tabulated as: R1, R2, and R3 in table 2. These numbers were imported
to Minitab14 software to be used for analysis by Taguchi design of experiments