patents ("citing patents") to earlier NIST
scientific and technical outputs ("cited NIST
By comparing the behavior of the new mercury clock and another NIST
optical clock based on aluminum, the NIST
team is seeking evidence that alpha may be changing today.
[u.sub.v] is the standard uncertainty in the calibration of the voltage ratio measurement instrumentation used at NIST
. This component does not apply if the force transducer being calibrated incorporates an indicating instrument that is part of the calibrated device.
Despite the loss of about a quarter of the transmitters, the NIST
team is reporting its initial findings, some of them striking.
The mechanical method uses a precision optical comparator to determine the total angle of the radius opening, and the optical method uses the NIST
C-series calibration system .
Next, the NIST
team cut the selected scratch patterns into the copper surfaces using a type of computer-controlled machine tool that was invented during the Cold War to hone superprecise nuclear-warhead parts.
"It's a big, exciting time for the clock community," says Jefferts, one of the leaders in the construction of the first NIST
fountain clock expected to become a primary standard.
The AES validation test suite is part of NIST
's CMVP, which encompasses validation testing for cryptographic modules and algorithms.
21 PHYSICAL REVIEW LETTERS, the NIST
group gives a new value for the Planck constant of 6.62606891 X [10.sup.-34] Joule-seconds, with an uncertainty of 87 parts per billion, less than half the uncertainty of prior measurements.
Over 280 computer scientists, vendors, voting rights activists, secretaries of state, and local election officials participated in NIST
's First Symposium on Building Trust and Confidence in Voting Systems in Gaithersburg, Md., on Dec.
A year from now, that VCR and other small devices could synchronize themselves to one of the most accurate clocks in the world, the one at the National Institute of Standards and Technology (NIST
) in Boulder, Colo.
11, 2003, NIST
hosted a workshop at the Boulder, CO, campus of NIST
on the thermophysical properties of the rocket propellant designated RP-1.