NUDTSNA at TREC 2015 Microblog Track: A Live Retrieval System Framework for Social Network based on Semantic Expansion and Quality Model. - Xiang Zhu; Jiuming Huang; Sheng Zhu; Ming Chen; Chenlu Zhang; Zhenzhen Li; Dongchuan Huang; Chengliang Zhao; Aiping Li; Yan Jia 001 (TREC, 2015)