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.
There is one form of propulsion for small toy boats that does not use a conventional engine. It is nevertheless a true heat engine ... Boats fitted with these simple devices are variously known as flash-steamers, hot-air-boats, toc-tocs (after a German version in the 1920s) or pop-pops.