Table 9 Design and results of Box-Behnken.

From: Calibration of contact parameters of sandy soil for planting tiger nut based on non-linear tools

No

B

D

E

Stacking angle/(°)

BP

BP-GA

WNN

1

− 1

− 1

0

28.51

28.54

28.52

28.51

2

1

− 1

0

30.67

30.64

30.65

30.66

3

− 1

1

0

29.76

29.52

29.60

29.75

4

1

1

0

35.02

35.04

35.03

34.99

5

− 1

0

− 1

29.59

29.53

29.54

29.55

6

1

0

− 1

34.30

34.31

34.30

34.30

7

− 1

0

1

28.94

29.76

29.78

29.92

8

1

0

1

29.85

29.86

29.85

29.80

9

0

− 1

− 1

29.76

29.52

29.60

29.75

10

0

1

− 1

33.55

33.54

33.55

33.53

11

0

− 1

1

29.56

28.92

28.93

29.54

12

0

1

1

31.43

31.45

31.42

31.43

13

0

0

0

31.96

31.45

31.53

31.85

14

0

0

0

31.43

31.46

31.45

31.43

15

0

0

0

30.97

31.53

31.53

30.89

16

0

0

0

31.82

31.47

31.53

31.51

17

0

0

0

31.49

31.54

31.51

31.94