Courtesy of Boeing 'Spoofing,' or intentionally generating fake GPS signals, is a threat that governments have yet to be addressed. An American bat-wing RQ-170 Sentinel—a U.S. military drone—was flying over Iran en route to its Afghanistan base in December when, Iranian military engineers claim, they reconfigured the drone's global-positioning-system coordinates to fool it into landing, intact, on Iranian soil. The U.S. military claims the drone simply malfunctioned.On Feb. 22, GPS industry experts from around the world gathered in Teddington, U.K., to discuss the system's vulnerabilities. Bob Cockshott, a director at Britain's Intelligent Communications Technology Knowledge Transfer Network and a conference
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.