Program for Updating Parameters of Thermal Models

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.