Cross-Layer Co-Design and Physics-Grounded Evaluation of Hybrid Reinforcement Learning and Federated ANN-PID Protocol Suites for Dense Urban UAV Delivery Networks (Randa Shaker Abd-Alhussain, Qasim Radam Mahmood, Hasan Mohammed Taqi Salih Albdair, Mohammad Khaleel Sallam Ma’aitah, Sanad Abdullah Alafghani, Ashraf Al-Shaikh Khalil, & Ashraf Zaher, Trans.). (2026). Babylonian Journal of Machine Learning, 2026, 164-196. https://doi.org/10.58496/BJML/2026/013