STEAM: A Hierarchical Co-Simulation Framework for Superconducting Accelerator Magnet Circuits. - Lorenzo Bortot; Bernhard Auchmann; Idoia Cortes Garcia; Alejando M. Fernando Navarro; Michal Maciejewski; Matthias Mentink; Marco Prioli; Emmanuele Ravaioli; Sebastian Schöps; Arjan Verweij (CoRR, 2018)