Rapid and Simultaneous Prediction of Eight Diesel Quality Parameters through ATR-FTIR Analysis

Table 7

Validation results of prediction models for quality parameters of diesel.

	Density	Flash point	Sulfur content	T10	T50	T85	Cetane index	Biodiesel content
Unit	kg·m^−3	°C	% (w/w)	°C	°C	°C	—	% (v/v)
Measured interval	831.6 to 860.4	8 to 70	0.01 to 0.19	158.9 to 234.1	256.3 to 305.8	330 to 369.5	42.2 to 51.0	0.6 to 7.4
Variable selection	GA	GA	FiPLS	BiPLS	GA	None	BiPLS	GA
Number of variables	439	380	175	1563	410	1738	1363	452
Number of LVs	9	7	5	10	5	8	7	6
Accuracy
RMSEC	0.4	2	0.01	3.9	3.0	4.6	0.6	0.2
RMSECV	0.5	2	0.01	4.4	3.4	5.1	0.6	0.2
RMSEP	0.4	2	0.01	4.1	3.0	4.7	0.6	0.2
r (cal)	0.997	0.930	0.987	0.940	0.954	0.814	0.919	0.946
r (CV)	0.996	0.900	0.984	0.922	0.941	0.770	0.903	0.936
r (val)	0.997	0.889	0.987	0.925	0.957	0.799	0.917	0.937
ARE (%)	0.04	3.72	14.10	1.68	0.77	1.06	0.95	3.18
RPD	12.89	2.19	5.93	2.63	3.44	1.64	2.49	2.83
Linearity
R^2 cal	0.994	0.866	0.974	0.883	0.909	0.662	0.845	0.894
R^2 CV	0.993	0.809	0.969	0.851	0.886	0.593	0.815	0.877
R^2 val	0.994	0.791	0.974	0.855	0.916	0.639	0.841	0.878
Bias	0.002	0.049	−0.002	0.325	0.340	0.822	−0.086	−0.037
tbias	0.05	0.26	2.20	0.91	1.33	2.06	1.66	2.16
Intermediary precision	1.5	2	0.01	1.9	1.5	2.1	0.4	0.1
RSD (%)	0.04	5.91	9.00	0.93	0.44	0.47	0.40	0.95

^∗t critical (95% confidence level; 135 degrees of freedom) = 1.98.