A Mathematical Model of the Sam Animal Calorimeter Respiratory Gases and Related Computer Technics
Abstract:
Problems related to effects of air flow upon measurements of oxygen and carbon dioxide concentrations in the chamber caused us to modify the animal calorimeter system in use at the USAF School of Aerospace Medicine. Differential equations were developed to describe the fractional concentrations of respiratory gases under steady state conditions. Their solutions gave the gas responses attributable to the subject. Sensor signals were amplified for increased sensitivity and scaled for magnetic tape recording by an analog computer. Radiant and evaporative heats were scaled to record values in units of Caloriesminute. These parameters, along with signals of the oxygen and carbon dioxide sensors, corrected for equipment drift, were appropriately treated by a digital computer program to yield oxygen consumption, carbon dioxide production, respiratory quotient, radiant heat, evaporative heat, total heat production, metabolic heat, and heat storage. Recalibration data of the radiant and evaporative heat sensors are included.