Abstract: A method of reproducing an original analog signal modified by a distortion and sampled. The distortion may be linear or nonlinear, and the samples may be either ideal or non-ideal. The method determines a stationary point of a cost function based on an error vector. The method iteratively computes approximated analog signals until the approximated analog signals converge to the original analog signal. The method may utilize Fr?chet derivatives and Moore-Penrose pseudo inverse transformations in order to iteratively compute the original analog signal. An apparatus performing said method is also disclosed.

Abstract: A method for determining functional residual capacity (FRC) of a patient while ventilating the patient. The system may include a medical ventilator which provides inhalation and exhalation from the patient, a sensor which measures a fraction one or more gas components of the inhalation and a fraction of the same gas components of the exhalation. A step change of oxygen fraction is provided to the inhalation of the patient. Subsequent to the step change, The fractions of the gas components are measured in the inhalation and in the exhalation. The functional residual capacity of the lungs of the patient is measured based on the fraction of the gas components in the inhalation and in the exhalation. The step change is provided manually by a technician, or automatically by programming a programmable device to provide the step change automatically to the patient by the medical ventilator. The step change is either an increase or a decrease in of the oxygen fraction.

Abstract: The alternating current potential drop ACPD technique is used to monitor surface cracks in electrical conductors. At high frequencies, the current flows in a superficial skin layer. Two distinct solutions are currently available for the thin and thick skin cases. However, there is no general solution that bridges these two modes in a seamless fashion. A numerical model is used to analyze the ACPD of a surface crack with uniform depth. A general solution is given that bridges the thin and thick skin solutions, which closely matches the numerical results, irrespective of the skin thickness. Methods for estimating depth of cracks are provided for surface penetrating cracks and back cracks.