OLES	Oil-line electrostatic sensor
FZG	A gear rig test
SFETs	Seeded fault engine tests
FIR	Finite Impulse Response
IPDS	Important potential debris signal
Uout	The output voltage of the charge amplification circuit
Q	The charge induced on the probe by the debris
Cf	The feedback capacitance of the amplifying circuit
q	The charge of the debris
D	The diameter of the probe
W	The axial length of the probe
θ	The azimuth angle of the micro-element sensing region S in the coordinate system of the model
z	The coordinate of the debris in the Z direction
x	The coordinate in the X direction
F(x, θ)	The distance between the projection N on the XOY plane of the debris and the micro-element S
Upeak	The peak value of the debris characteristic pulse
${\tau }_{width}$	The pulse width of the debris characteristic pulse
${\tau }_{delay}$	The delay time between the two pulses on the two probes induced by the debris
Dprobe	The distance between the two probes
$v_{debris}$	The velocity of the debris
Qp	The charge of the particle
α	A constant associated with the material of the debris and the medium the debris in
dp	The equivalent diameter of the particle
γ	The constant determined by the test