Before revision:  Experiments on motor imagery  and event-related potentials demonstrated the effectiveness and efficiency of our approach .
After revision:  Experiments on motor imagery and event-related potential classification verified that our proposed approach outperformed a state-of-the-art Riemannian space data alignment approach, and several approaches without data alignment. Conclusion: The proposed Euclidean space EEG data alignment approach can greatly facilitate transfer learning in BCIs. Significance: Our proposed approach is effective, efficient, and easy to implement. It could be an essential pre-processing step for EEG-based BCIs .