The United States has regained a coveted speed crown in computing with a powerful new supercomputer in Tennessee, a milestone for the technology that plays a major role in science, medicine and other fields.Frontier, the name of the massive machine at Oak Ridge National Laboratory, was declared on Monday to be the first to demonstrate performance of one quintillion operations per second — a billion billion calculations — in a set of standard tests used by researchers to rank supercomputers. The U.S. Department of Energy several years ago pledged $1.8 billion to build three systems with that “exascale” performance, as scientists call it.But the crown has a caveat. Some experts believe that Frontier has been beaten in th …
