Parametric studies of human thermal mechanisms and measurements

Abstract

A systematic methodology is proposed for mathematically quantifying the effects of measurement inaccuracies due to instrument uncertainty in a human calorimetry project. Human thermal mechanisms are poorly understood at the systems level and this study investigates the importance of these mechanisms quantitatively. The proposed methodology uses sensitivity derivatives combined with sensor accuracies to quantify the effect of each heat transfer mechanism contributing to the errors in the system equations. The method is applicable to any differentiable model to be validated by experimentation. To illustrate the methodology, two example cases, a reclining nude resting subject and a reclining clothed working subject, are analyzed. The calculated expected errors clearly suggest specific modifications.

Raynaud's Phenomenon: Infrared Functional Imaging Applied to Diagnosis and Drugs Effects

“…Analogous behaviour can also be traced for the equilibrium state. The generally lower equilibrium temperatures of the "PRP" fingers, with respect to the "SSc", could be explained in terms of reduced efficiency of the local thermoregulatory system caused by a reduced basal BF perfusion and by the unfavourable finger surface-to-volume ratio (41)(42)(43)(44)(45)(46)(47). Moreover, a "shared" weak thermoregulatory response could also explain the remarkable intra and inter individual homogeneity observed in the PRP group.…”

“…PRP behaviour is probably due to an equally low and constant BF in all fingers and to differences in the amount of heat exchanged with the environment, both processes being related to the finger surface area-to-volume ratio (37,(42)(43)(44)(45)(46)(47). In fact, the finger surface area is proportional to the amount of heat lost to the environment and the finger volume is proportional to the thermal capacity (the inertia to exchange heat with the surroundings).…”