Experimental performance analysis of a multiple-source and multiple-use heat pump system: a predictive ANN model of sky-source heat pumpKe Wen, Ryozo Ooka, Toshiyuki Hino, Mingzhe Liu, Doyun Lee, Wonjun Choi, Shintaro Ikeda and Djafar Reza PalaszE3S Web Conf., 111 (2019) 05018DOI: https://doi.org/10.1051/e3sconf/201911105018