The Army will announce today it has contracted with International Business Machines Corp. to build one of the world's fastest supercomputers to help develop more effective weapons systems.

The Defense Department will spend about $15 million on the supercomputer, which will be housed at the Army Research Laboratory's Major Shared Resource Center in Aberdeen, according to Dave Turek, an IBM vice president.

The supercomputer will perform at a peak speed of 10 teraflops, or 10 trillion mathematical operations per second, Turek said. A person with a calculator would need 8 million years to finish calculations the supercomputer can make in one second, he said.

Last week, the Navy selected IBM to build an even faster computer, at a cost estimated at less than $100 million, to produce weather forecasts for fleets at sea.

The Army's new supercomputer -- nicknamed "Stryker," after an armored Army combat vehicle -- will run on Linux, a free, "open source" operating system that is a rival to Microsoft Windows.

"These high-performing computing systems allow us to understand the physics behind" how weapons systems work, said Charles J. Nietubicz, director of the Army's research lab in Aberdeen.

For example, Nietubicz said, the Army may seek a lighter substitute for a 70-ton tank but "we can't make it more vulnerable."

"We can use composite materials, which may be stronger than steel in some cases. But how do we know it's going to work? Well, you use supercomputers to give the engineers and scientists a handle on whether it's even practical."