Research Article
Multivariable Regression and Adaptive Neurofuzzy Inference System Predictions of Ash Fusion Temperatures Using Ash Chemical Composition of US Coals
Table 3
Correlation coefficients (
) between AFTs and independent variables.
| Variable | IDT | ST | FT | Linear | Quadratic | Cubic | Linear | Quadratic | Cubic | Linear | Quadratic | Cubic |
| SiO2 | 0.60 | 0.602 | 0.625 | 0.64 | 0.64 | 0.67 | 0.68 | 0.71 | 0.72 | Al2O3 | 0.62 | 0.64 | 0.65 | 0.68 | 0.69 | 0.70 | 0.75 | 0.75 | 0.77 | CaO | 0.17 | 0.20 | 0.21 | 0.18 | 0.22 | 0.22 | 0.24 | 0.27 | 0.28 | MgO | 0.018 | 0.02 | 0.02 | 0.018 | 0.02 | 0.03 | 0.02 | 0.03 | 0.04 | MnO | 0.11 | 0.17 | 0.23 | 0.12 | 0.19 | 0.25 | 0.14 | 0.23 | 0.29 | Na2O | 0.006 | 0.008 | 0.009 | 0.008 | 0.009 | 0.01 | 0.01 | 0.011 | 0.014 | K2O | 0.02 | 0.025 | 0.046 | 0.035 | 0.036 | 0.06 | 0.06 | 0.06 | 0.08 | Fe2O3 | 0.60 | 0.67 | 0.68 | 0.63 | 0.68 | 0.68 | 0.63 | 0.65 | 0.65 | TiO2 | 0.26 | 0.39 | 0.41 | 0.29 | 0.44 | 0.46 | 0.31 | 0.49 | 0.53 | P2O5 | 0.001 | 0.004 | 0.007 | 0.001 | 0.006 | 0.008 | 0 | 0.004 | 0.005 | SO3 | 0.18 | 0.24 | 0.25 | 0.21 | 0.26 | 0.27 | 0.27 | 0.32 | 0.32 | Base | 0.76 | 0.84 | 0.84 | 0.80 | 0.86 | 0.86 | 0.84 | 0.85 | 0.85 | Acid | 0.74 | 0.81 | 0.81 | 0.79 | 0.84 | 0.84 | 0.84 | 0.85 | 0.85 | Base/Acid | 0.58 | 0.76 | 0.82 | 0.63 | 0.81 | 0.86 | 0.72 | 0.85 | 0.87 | Dolomite ratio | 0.015 | 0.11 | 0.21 | 0.01 | 0.11 | 0.21 |
0.003 | 0.07 | 0.18 | Silica ratio | 0.76 | 0.80 | 0.80 | 0.80 | 0.82 | 0.82 | 0.84 | 0.84 | 0.84 | SiO2/Al2O3 | 0.004 | 0.004 | 0.007 | 0.005 | 0.006 | 0.009 | 0.009 | 0.01 | 0.014 | Fe2O3/CaO | 0.09 | 0.10 | 0.10 | 0.09 | 0.10 | 0.10 | 0.07 | 0.07 | 0.07 |
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