Ambient Media and Systems: Second International ICST Conference, AMBI-SYS 2011, Porto, Portugal, March 24-25, 2011, Revised Selected Papers (Lecture ... and Telecommunications Engineering, 70) Ambient Media and Systems: Second International ICST Conference, AMBI-SYS 2011, Porto, Portugal, March 24-25, 2011, Revised Selected Papers (Lecture ... and Telecommunications Engineering, 70) Paperback