“…With sufficient number of devices (carried by rescue workers and/or volunteers) roaming the area, communication with survivors may be possible via PSNs. Similarly, PSNs are applicable when groups of people get separated in crowded areas (e.g., survivors in a city after an earthquake) and need to locate members [121]. Urban sensing: With handheld user devices as platforms for people-centric sensing [123], PSNs can be exploited to collect data ubiquitously for urban sensing (e.g., for studying city dynamics and urban social behavior).…”