Cost function analysis applied to the determination of aorta parameters

It has been shown by Fich and Welkowitz that a model of the aorta which is tapered in area and elastic constant and is essentially reflectionless is a good representation for the calculation of pressure and flow wave propagation in the aorta. If one then measures a steady state pressure transfer function in the aorta and relates it to the steady state pressure transfer function of the model, it is possible to adjust the physical parameter values that appear in the model until the transfer functions coincide. By this means it is possible to determine the physical parameters of the aorta.

Both analog and digital data techniques were developed for efficient handling of the data. Matching of the transfer functions was accomplished by finding the ‘best’ set of parameters that minimized a weighted error cost function derived from the magnitude and phase of the transfer functions.