PMC

Blade modal shapes. (a) Flawless state (N); (b) Blade tip crack (Tip 1); (c) Blade tip crack (Tip 2); (d) Blade tip crack (Tip 3); (e) Blade middle crack (Middle 1); (f) Blade middle crack (Middle 2); (g) Blade middle crack (Middle 3); (h) Blade root crack (Root 1); (i) Blade root crack (Root 2); and (j) Blade root crack (Root 3).

Variables are expressed in dimensionless standardized units. Fencer A: Reflected tip distance increased with increased reflected blade distance (linear regression, both variables square root transformed for regression but not plotting, n = 67, p = 0.00016, r² = 0.20, slope_std = 0.45, plot). Not significantly related to reflected tip distance (forward step-wise linear regression) were angular blade velocity (p = 0.8), reflected blade velocity (p = 0.2), blade height (p = 0.9), reflected blade height (p = 0.05), and blade distance (p = 0.03). Fencer B. Reflected tip distance increased with increased reflected blade distance (linear regression, both variables square-root transformed for regression, n = 78, p<0.000001, r² = 0.29, slope = 0.62 based on non-transformed data). Not significantly related to blade velocity (p = 0.7), reflected blade velocity (p = 0.6), blade height (p = 0.3), reflected blade height (p = 0.2), or blade distance (p = 0.0005). Tip velocity was affected by both angular blade velocity and blade height (linear regression, n = 78, r² = 0.44). Tip velocity increased with increased angular blade velocity (multiple linear regression, n = 78, p<0.00001, slope_std = 0.59, partial plot). Tip velocity increased with decreased blade height (multiple linear regression, n = 78, p<0.00001, slope_std = -0.65, partial plot). Not significantly related to tip velocity (forward step-wise linear regression) were reflected angular velocity (p = 0.02), reflected blade height (p = 0.8), blade distance (p = 0.1), reflected blade distance (p = 0.6).

Frequency distribution patterns of the blade length and the blade width of S. japonica × S. longissima BC₁F₂ population at four serial observation days. (A) The blade length frequency distribution of S. japonica × S. longissima BC₁F₂ population measured at April 17^th. (B) The blade width frequency distribution of S.japoncica × S. longissima BC₁F₂ population measured at April 17^th. (C) The blade length frequency distribution of S. japonica × S. longissima BC₁F2 population measured at May 8^th. (D) The blade width frequency distribution of S. japonica × S. longissima BC₁F₂ populaltion measured at May 8^th. (E) The blade length frequency distribution of S. japonica × S. longissima BC₁F₂ populaltion measured at May 22^th. (F) The blade width frequency distribution of S. japonica × S. longissima BC₁F₂ populaltion measured at May 22^th. (G) The blade length frequency distribution of S. japonica × S. longissima BC₁F₂ populaltion measured at June 9^th. (H) The blade width frequency distribution of S. japonica × S. longissima BC¹F² populaltion meausred at June 9^th.

The normal process that blade-impactor tightens the helical blade. Pay attention to the size of the gap on this helical blade in the physical pictures and the position of internal screw nut in the analog diagrams. a. A locked helical blade is supplied, with no gap existing. b. Counterclockwise rotations gets the external screw thread of the impactor connected tight with internal screw thread of the helical blade, at the same time the internal screw nut moves inward and the gap on the blade appears. c. After 5 times of clockwise-rotations, the connection between external screw thread of the impactor and internal screw thread of the helical blade gets looser, at the same time the internal screw nut moves outward and the gap on the blade gets smaller. d. The helical blade is locked, at the same time the gap on the blade disappears.