The group meeting of Week 12 of MAGIC Lab was held online on May 21st, 2020. Ali first introduced a related paper, and then reported his work. The topic work was "Optimal Control of Connected and Automated Vehicles at Roundabouts: An Investigation in a Mixed-Traffic Environment". Then, the report was "Optimal Control of Single-lane Roundabout under Connected and Automated Vehicles Environment". Participants in this report included Professor Ma Wanjing, Assistant Professor Wangling, Assistant researcher Yu Chunhui and other members of MAGIC Lab.