Classifying, Predicting, and Reducing Strategies of the Mesh Excitations of Gear Whine Noise: A Survey

Table 2

Sign functions for frictional excitations.

Sign functions	Reference
	[173, 177]
		[178]
	[175, 176, 189]
	[181]
	[190]

The definition and value of each coefficient in the formula can be found in the corresponding reference.