During 1990â2003, Pakistan sustained its historical lead as the second-most urbanized nation in South Asia with city dwellers making up 36% of its population. Furthermore, 50% of Pakistanis now reside in towns of 5,000 people or more.
Submarine Propulsion Systems. During World War II, most American submarines were powered by diesel-electric systems. This was a departure from earlier submarine power systems, which were direct drive types, little changed from the earliest boats. In this direct-drive power system, the diesel engine is directly connected to the propeller shaft.
HMS Ambush, the Royal Navy's newest nuclear attack submarine, is one of the most sophisticated and powerful vessels of her type ever built. The giant Astute-class sub, which was launched today, is so hi-tech she doesn't even need a periscope. Scroll down to watch the submarine's weapons being tested...