Predictability of Al-Mn Alloy Exposure Time Based on Its As-Cast Weight and Corrosion Rate in Sea Water Environment

This paper presents the predictability of aluminium-manganese alloy exposure time based on its as-cast weight and corrosion rate in sea water environment. The validity of the derived model: α = 26.67γ + 0.55β?- 0.29 is rooted on the core expression: 0.0375α = γ + 0.0206β?- 0.0109 where both sides of the expression are correspondingly approximately equal. Statistical analysis of model-predicted and experimentally evaluated exposure time for each value of as-cast weight and alloy corrosion rate considered shows a standard error of 0.0017% & 0.0044% and 0.0140% & 0.0150% respectively. The depths of corrosion penetration (at increasing corrosion rate: 0.0104 - 0.0157 mm/yr) as predicted by derived model and obtained from experiment are 0.7208 × 10-4 & 1.0123 × 10-4 mm and 2.5460 × 10-4 & 1.8240 × 10-4 mm (at decreasing corrosion rate: 0.0157 - 0.0062 mm/yr) respectively. Deviational analysis indicates that the maxi- mum deviation of the model-predicted alloy exposure time from the corresponding experimental value is less than 10%.

Predictability of Hardness of the Heat Affect Zone in Aluminum Weldments Cooled in Palm Oil Based on Hardness of Similarly Cooled Mild Steel and Cast Iron Weldments

The predictability of hardness of the heat affected zone (HAZ) in aluminum weldments cooled in palm oil, based on hardness of similarly cooled mild steel and cast iron weldments has been ascertained. The general model: α = 1.2769? indicates that HAZ hardness of aluminium weldment is dependant on the ratio of product to sum of HAZ hardness of mild steel and cast iron weldments cooled in palm oil under the same conditions. The maximum deviations of the model-predicted HAZ hardness values α, μ and β from the corresponding experimental values αexp, μexp and βexp were less than 0.04% indicating the reliability and validity of the model.

Model for Assessment Evaluation of Methane Gas Yield Based on Hydraulic Retention Time during Fruit Wastes Biodigestion

This paper presents an assessment evaluation of methane gas yield using a derived model based on the hydraulic retention time (HRT) of the feed stock (waste fruits) undergoing biotreatment in the digester. The derived model;γ = e(3.5436 α + 2.0259) indicates an exponential relationship between methane yield and the HRT. Statistical analysis of the model-predicted and experimental gas methane yield for each value of HRT considered shows a standard error of 0.0081 and 0.0114% respectively. Furthermore, the correlation between methane yield and HRT as obtained from derived model and experimental results were evaluated as 0.9716 and 0.9709 respectively. Methane gas yield per unit HRT as obtained from derived model and experiment are 0.0196 and 0.0235 (m3kg-1 VS) days-1 respectively. Deviational analysis indicates that the maximum deviation of the model-predicted methane yield from the corresponding experimental value is less than 16%. It was also found that the validity of the model is rooted on the expression 0.2822 ln γ = α + 0.5717 where both sides of the expression are correspondingly approximately equal.