Besides, it might be attributed to the complex wear mechanisms due to variable dimensional asperities
and wear debris effect.
Typically, the interaction between surface asperities
and fluid becomes noticeable when the local clearance decreases to the range of surface asperities
height and is then still of low impact.
Felder  proposed the dimensionless parameter [H.sub.f] = 3nlu/p[R.sub.a.sup.2], where [R.sub.a] is the arithmetic mean value and l is the space between two consecutive asperities
. He proposes this expression in order to obtain a parameter in the form of [p.sub.l]/p, where [p.sub.l] is the theoretical pressure induced by the pouches generated by the microgeometry.
(5) Relocated wear debris and particles did not severely sheath the top asperities
of PMMA surfaces
At the fault plane, there are 6 asperities
, which indicates that the earthquake is composed of at least 6 subevents.
During the applying stress, aperture distribution of fracture would be change and some asperities
According to the Hertz solution for a single elastic sphere, Greenwood and Williamson  proposed that interaction between contacting asperities
was equivalent to contact between a rough surface comprising spherical asperities
of constant radius and an ultra-smooth flat surface.
When the sliding velocity is low, the pressure in the oil film is unable to support the normal load induced by the chain force and asperities
on both surfaces are in direct contact with each other.
Stochastic models assume that surface roughness consists in many tiny asperities
having a specific probability distribution (e.g., Gaussian) of heights and curvatures, which deform independently of each other.
height of residual asperities
is reduced on this surface.
The scrotum content appeared to be stuck to the skin, and the overlying skin was rough with asperities
In boundary lubrication stage, engagement pressure is together borne by the oil film pressure and the asperity contact of friction pair, and transmitted torque involves the viscous shear torque of oil film and the asperity friction torque of friction pair, and with wet clutch engaging, contact and friction of asperities
gradually play a dominant role in the formation of pressure and torque.