U.S. Patent  Dec. 31, 2019  Sheet 6 of 7  US 10,520,813 B2  0  S+  N  y  S+  s  p  S+  N  ~]  S+  0  0 S+ 0  Q  N  S+ N  s  p  S+  s  s  cc  cc  FIG. 8H  FIG. 8G  FIG. 8D  FIG. 8E  FIG. 8F  FIG. 8C  FIG. 88  FIG. 8A 