Energies 2021 , 14 , 3203
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Table4. The coefficient of determination R 2 between crushing and average normalized values.
Cardboard Index
BNT 0.823 0.885 0.815 0.972
SST 0.983 0.998 0.970 0.957
TST 0.996 0.846 0.876 0.742
B-285 B-410 C-340 C-440
We found that there is a relationship between the decreased ECT and THK2 value. A reference line, which capture the relationship between the decrease of these normalized parameters and crushing of the corrugated cardboard was established. The equation describing the reference line has a following form: y = 1 − 0.53 x (5) where: y —the normalized parameter value and x —the crushing value. In Figure 15, the normalized ECT and THK2 values for the analysed corrugated cardboards fitting to the reference lines represented by the Equation (5) are presented.
( a )
( b )
( c )
( d )
Figure15. The decreases in normalized ECT and THK2 values for corrugated board with an index: ( a ) B-285; ( b ) B-410; ( c ) C-340 and ( d )C-440. For the reference line and normalized ECT and THK2 values, the coefficients of determination R 2 were computed (Table 5), according to Equation (1) for the two sets of data simultaneously, where: x i —reference line value calculated from the Equation (5), ˆ y i —normalized ECT and THK2 values and var ( x ) —variance of the reference line value. Table 5. The coefficient of determination R 2 between reference line and normalized ECT and THK2 values.
R 2
Cardboard Index
B-285 B-410 C-340 C-440
0.985 0.982 0.965 0.995
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