Department of Computer Systems and Sciences, Stockholm University, Stockholm 164 25, Sweden. · Department of Information Engineering, University of Pisa, Pisa, Italy. · Distributed Systems Group, TU Wien, Vienna 1040, Austria and ICREA Barcelona 08002, Spain
School of Cyber Science and Engineering, Xi’an Jiaotong University, China · School of Mechatronic Engineering and Automation, Shanghai University, China