TY - Journal of Systems Engineering and Electronics A1 - Gaofeng WU, Kaifang WAN, Xiaoguang GAO, Xiaowei FU T1 - Placement of unmanned aerial vehicles as communication relays in two-tiered multi-agent system: clustering based methods Y1 - 2020-04-30 JF - Journal of Systems Engineering and Electronics JO - Journal of Systems Engineering and Electronics SP - 231 EP - 242 VL - 31 IS - 2 UR - https://www.jseepub.com N1 - 10.23919/JSEE.2020.000001 ER -