China has built the world's fastest supercomputer, almost twice as fast as the previous U.S. holder and underlining the country's rise as a science and technology powerhouse.

The semiannual TOP500 official listing of the world's fastest supercomputers released Monday says the Tianhe-2 developed by the National University of Defense Technology in central China's Changsha city is capable of sustained computing of 33.86 petaflops. That's the equivalent of 33,860 trillion calculations per second.

The Tianhe-2, which means Milky Way-2, knocks the U.S. Department of Energy's Titan machine off the no. 1 spot. It achieved 17.59 petaflops per second.

Supercomputers are used for complex work such as modeling weather systems, simulating nuclear explosions and designing jetliners.

It's the second time China has been named as having built the world's fastest supercomputer. In November 2010, the Tianhe-2's predecessor, Tianhe-1A, had that honor before Japan's K computer overtook it a few months later.

The Tianhe-2's achievement shows how China is leveraging rapid economic growth and sharp increases in research spending to join the United States, Europe and Japan in the global technology elite.

"Most of the features of the system were developed in China, and they are only using Intel for the main compute part," said TOP500 editor Jack Dongarra.

"That is, the interconnect, operating system, front-end processors and software are mainly Chinese," said Dongarra, who toured the Tianhe-2 development facility in May.