Nomenclature	Definition
α	Quantification of the symmetric broadening of the relaxation distribution
τ	Relaxation time
σ	Ionic conductivity
γ	Quantification of the asymmetric broadening of the relaxation distribution
ω	Angular frequency
Δ	Increase
∇	Decrease
d	Dipole rotation
E	Rms electric field
ε*	Complex relative permittivity
ε′	Dielectric constant
ε″	Loss factor
Δε	Dielectric length
α dispersion	Alpha dispersion
β dispersion	Beta dispersion
λ dispersion	Gamma dispersion
f	Frequency
LR	Return loss
Mltr	Permittivity maturity index
Mp	Permittivity maturity index
tan δ	Loss tangent
BP	BP network model
Dp	Penetration depth
ELM	Extreme Learning Machine
FAST	Fast clustering based feature subset selection
FDS	Frequency domain spectrometer
FF	Full Frequency
GRNN	Generalized Regression Neural Network
LCR	Inductance Capacitance Resistance analyser
MW	Microwave
P	Power dissipated
PCA	Principal Component Analysis
PCA-BP	Principal Component Analysis using the BP model
PCA-SVR	Principal Component Analysis using the SVR model
PCA-SVR	Principal Component Analysis using the SVR model
RF	Radio Frequency
RMSE	Root Mean Square Error
SPA	Successive Projection Algorithm
SPA-BP	Successive Projection Algorithm using the BP model
SPCA	Sparse Principal Component Analysis
SRC	Sparse representation classification
SSC	Soluble Solid Content
SVM	Support Vector Machine
SVR	Support Vector Regression
SWR	Standing Wave Ratio
UVE-PLS	Uninformative Variation Eliminations
WLR	Weight Loss Rate