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In this paper, the problem of the quantitative characterization of thermal resistance fields in a multilayer sample is addressed by using the classical front face flash method as the thermal excitation and infrared thermography (IRT) as the monitoring sensor. In this challenging problem, the complete inverse processing of a multilayer analytical model is difficult due to the lack of sensitivity of some parameters (layer thickness, depth of thermal resistance, etc.) and the expansive computational iterative processing. For these reasons, the proposed strategy is to use a simple multilayer problem where only one resistive layer is estimated. Moreover, to simplify the inverse processing often based on iterative methods, an asymptotic development method is proposed here. Regarding the thermal signal reconstruction (TSR) methods, the drawback of these methods is the inability to be quantitative. To overcome this problem, the method incorporates a calibration process originating from the complete analytical quadrupole solution to the thermal problem. This analytical knowledge allows self-calibration of the asymptotic method. From this calibration, the quantitative thermal resistance field of a sample can be retrieved with a reasonable accuracy lower than 5%. [ABSTRACT FROM AUTHOR]

Raw signal simulation is an important tool to test the effectiveness of the system parameters and imaging algorithms. A fast raw signal simulation method for multi-circular synthetic aperture imaging is proposed based on the inverse processing of the imaging algorithm and the nonuniform fast Fourier transform. The analytical description and processing procedure are presented. Simulation results of an ideal point target and a human model demonstrate the validity and effectiveness. Compared with the common time-domain method, the proposed method can achieve equivalent performance with higher efficiency. [ABSTRACT FROM AUTHOR]

In this letter, a simulation procedure for airborne stripmap synthetic aperture radar with zero squint angle is proposed. The procedure is based on the idea of inverse processing and 1-D summation. It utilizes narrow bandwidth approximation and is more efficient compared to a time-domain simulator. Moreover, it allows for the simulation of raw data for higher aperture angle configurations compared to existing approaches. The effectiveness of the approach is demonstrated by means of examples for point scatterers. [ABSTRACT FROM PUBLISHER]