Issue 60

D. S. Lobanovet alii, Frattura ed Integrità Strutturale, 60 (2022) 146-157; DOI: 10.3221/IGF-ESIS.60.11

c Figure 5: Relationship between weight gain and exposure time for the composite exposed to process water (a), sea water (b), and machine oil (c) solutions at different temperatures

Std. Error of Estimate

Model

R 2

Adjusted R 2

F-value

p-value

Add. mod.

0.554

0.541

0.27

43.48

< 0.001***

Full mod. < 0.001*** Significance levels: ***p-val. ≤ 0.001 (significant), **p-val. ≤ 0.01 (very significant), *p-val. ≤ 0.05 (highly significant). Table 6: Model summary results for weight gain Model Coefficient Std. Error t-value p-value Confidence Interval [0.025 0.975] 1 Pr. water 0.167 0.051 3.286 0.001*** 0.066 0.267 Sea water 0.245 0.049 5.019 < 0.001*** 0.149 0.342 Temp. -0.0010 0.0006 -1.882 0.062 -0.0021 0.0001 Time 0.0108 0.0014 7.930 < 0.001*** 0.0081 0.0135 2 Time 0.0003 0.0039 0.080 0.937 -0.0074 0.0081 Temp.×Time -1.2×10 -5 5.5×10 -5 -0.216 0.829 -0.00012 9.7×10 -5 Pr. water×Temp.×Time 0.00020 8.0×10 -5 2.461 0.015* 0.00004 0.00036 Pr. water×Time 0.0049 0.0056 0.877 0.382 -0.0062 0.0161 Sea water×Temp.×Time 0.00017 7.8×10 -5 2.180 0.031* 0.00002 0.00032 Sea water×Time 0.0119 0.0055 2.143 0.034* 0.0009 0.0228 Significance levels: ***p-val. ≤ 0.001 (significant), **p-val. ≤ 0.01 (very significant), *p-val. ≤ 0.05 (highly significant). Table 7: Multiple linear regression results for weight gain. The second model is represented as 0.774 0.764 0.19 78.64

WeightGain = 0.0003×Time - 1.2×10 -5 ×Temp.×Time + + 0.0002×Pr.Wat.×Temp.×Time + 0.0049×Pr.Wat.×Time + + 0.00017×SeaWat.×Temp.×Time + 0.0119×SeaWat.×Time The simplified model equations are shown here

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