  From simple physical systems to full production lines, numerical models could
be used to minimize downtime and to optimize performances. In this article, the
system of interest is the SPIRAL2 (Syst\`eme de Production d'Ions RAdioactifs
en Ligne de 2e g\'en\'eration) particles accelerator cryogenic system. This
paper illustrates three totally different applications based on a SPIRAL2
cryostat model: optimal controller synthesis, virtual sensor synthesis and
anomaly detection. The tow firsts applications have been deployed on the
system. Experimental results are used to illustrate the benefits of such
applications.
