Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA. kangpeng@ist.temple.edu|Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA. kangpeng@ist.temple.edu|Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA. kangpeng@ist.temple.edu|Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA. kangpeng@ist.temple.edu|Center for Information Science and Technology, Temple University, Philadelphia, PA 19122, USA. kangpeng@ist.temple.edu