Estimating and testing for influence of specific structural factors on aging of refrigerated vehicles

This paper introduces a mathematical formulation for the aging curve to study the effects that structural characteristics, as well as operation and maintenance practices, have on the life of refrigerated transport units. From a large database of measurements and real aging data, we fitted the proposed model and we performed inference on parameters using a nonparametric permutation approach. The proposed testing permutation approach, we validated via a Monte Carlo simulation study, appears to be a flexible method, suitable to be implemented for nonlinear models, such as the presented aging curve. The proposed algorithm, although general in its kind, offers a well-rounded approach to make inference on nonlinear model via permutation test. As final results of this, we were able to identify and quantify the most relevant specific structural factors affecting the aging of refrigerated vehicles, which are the presence of meat rails in the roof and the number of leafs for the first and second door.