Parameter Identification in Thermal Networks (PITN) is a computer program developed to satisfy a need to update parameters in mathematical models of thermal systems in order to make the temperatures computed by the models equal to the temperatures measured in tests of the corresponding real systems. PITN is suitable for application to network-type models of scientific instruments and general engineering systems, including telescopes, spectrometers, and spacecraft. Relative to software developed previously for the same purpose, PITN can readily be applied to more complex models and yields results in less time. In addition, PITN can accommodate nonlinearities in thermal models (nonlinearities are typically associated with radiative heat transfer). PITN is based partly on the formulation of the parameter-matching problem as a nonlinear least-squares optimization problem, which can be solved by use of very fast and robust optimization techniques. The speed and accuracy of computations are increased by use of analytic expressions for temperature differentials.

This program was written by Miltiadis Papalexandris and Mark Milman of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at under the Software category.

This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393-3425. Refer to NPO-21067.