Adam	adaptive moment estimation
AI	artificial intelligence
ALSTM	attention-based long short-term memory
BPNN	backpropagation neural network
BR	Bayesian regression
CALCE	center for advanced life cycle engineering
CL	convolutional layer
CNN	convolutional neural network
CWT	continuous wavelet transform
CWTCNN-HI	continuous wavelet transform and CNN-based health indicator
DAE	deep autoencoder
DNN	deep neural network
ELM	extreme learning machine
FDF	frequency domain feature
FFT	fast Fourier transformation
FPT	first predicting time
FSPS	frequency spectrum partition summation
GBDT	gradient boosting decision tree
GPR	Gaussian process regression
GR	Gaussian regression
GRU	gated recurrent unit
HHT	Hilbert-Huang transform
HLR	high-level representation
Leaky ReLU	leaky rectified linear unit
LDA	linear discriminant analysis
LR	linear regression
LS-SVR	least squares-support vector regression
LSTM	long short-term memory
MAE	mean absolute error
MDGRU	multi-dimensional gated recurrent units
MSCNN	multi-scale CNN
MSE	mean squared error
PCA	principal component analysis
PHM	prognostics and health management
RBM	restricted Boltzmann machine
ReLU	rectified linear unit
RF	random forest
RMS	root mean square
RMSE	root mean squared error
RNN	recurrent neural network
RNN-HI	RNN-health indicator
RS	related-similarity
RUL	remaining useful life
SOM-HI	self-organizing map based health indicator
SSH	single scale-high
SSL	single scale-low
STFT	short-time Fourier transform
SVD	support vector data
SVM	support vector machine
SVR-HI	support vector regression health indicator
TDF	time domain feature
TFDF	time-frequency domain feature
TFR	time frequency representation
TSMC	time series multiple channel
WT	wavelet transform