HMM	Hidden Markov model
EM	Expectation–maximization
WLS	Weighted least squares
RUL	Remaining useful life
TPM	Transition probability matrix
CM	Condition monitoring
HI	Health indicator
MAD	Median absolute deviation
BIC	Bayesian information criterion
CV	Cross-validation
RMSE	Root mean squared error
MAE	Mean absolute error
EPE	Expected prediction error
NASA C–MAPSS	NASA Commercial Modular Aero-Propulsion System Simulation dataset