Shun Maeda Chunzhi Gu Jun Yu 0012 Shogo Tokai Shangce Gao Chao Zhang 0030 Frequency-guided multi-level human action anomaly detection with normalizing flows. 112770 2026 172 Pattern Recognit. https://doi.org/10.1016/j.patcog.2025.112770 db/journals/pr/pr172.html#MaedaGYTGZ26 streams/journals/pr