
Variable  Definition 

p(x)  The probability density function from the observed vibration signal’s amplitude 
x  The vibration amplitude 
 Waveform index 
 Impulse index 
 Margin index 
 Peak index 
 Kurtosis index 
 A dimension parameter named as root of mean square(RMS) 
 The sensitivity of the th kind of nondimensional index detector to the jth kind of failure 
 The effective information preserved in the total feature information of a dimensionless index to generate a mature immune detector 
 The diagnosis capability factor of the kind of th dimensionless index immune detector to the kind of jth fault 
