Title:  Knowledge-Based Re-engineering of Legacy Programs for
        Robustness in Automated Design
Authors: J. Keane and T. Ellman
Abstract:


Systems for automated design optimization of complex real-world
objects can, in principle, be constructed by combining
domain-independent numerical routines with existing domain-specific
analysis and simulation programs. Unfortunately, such ``legacy''
analysis codes are frequently unsuitable for use in automated design.
They may crash for large classes of input, be numerically unstable or
locally non-smooth, or be highly sensitive to control parameters.  To
be useful, analysis programs must be modified to reduce or eliminate
only the undesired behaviors, without altering the desired
computation.  To do this by direct modification of the programs is
labor-intensive, and necessitates costly re-validation.


We have implemented a high-level language and run-time environment
that allow failure-handling strategies to be incorporated into
existing Fortran and C analysis programs while preserving their
computational integrity.  Our approach relies on globally managing the
execution of these programs at the level of discretely callable
functions so that the computation is only affected when problems are
detected.  Problem handling procedures are constructed from a
knowledge base of generic problem management strategies.  We show that
our approach is effective in improving analysis program robustness and
design optimization performance in the domain of conceptual design of
jet engine nozzles.