1. Department of Information Science; University of North Texas; 1155 Union circle #311068, Denton TX 76203 USA
2. School of Information Management; Central China Normal University; No. 152, Luoyu Road, Wuhan Hubei 430079 P.R. China
3. Intelligent Information Access Lab, University of North Texas; 1155 Union circle #311068, Denton TX 76203 USA