Mass
NIST
Researchers Approach Non-Physical Standard for Kilogram
Scientists
at the National Institute of Standards and Technology (NIST) love
precision. Yet one group of the agency’s researchers is going
to extremes, even by NIST standards.
They
run air conditioning (AC) in from an adjacent building since AC
causes tiny vibrations that could disturb their work. They favor
an isolated building that includes much wood construction because
wood does not cause minute warps in magnetic fields.
They
do all this because they are working on a truly weighty matter:
redefining the kilogram.
The
world’s measurement authority, the International System of
Units (known as SI), includes seven basic units that define how
we quantify things such as time, length and temperature. The kilogram
represents the “final frontier” for the SI because it
is the only unit still based on a physical standard—a century-old
platinum-iridium cylinder stored in France. The other units are
based on unchanging physical phenomena such as the speed of light.
NIST’s
electronic kilogram project is designed to redefine mass in terms
of fundamental physics and quantum standards. This is being achieved
with a two-story-high apparatus that measures—with extraordinary
precision—how much current passes through a wire coil in
a strong magnetic field to balance the pull of grav-ity on a one-kilogram
mass standard, and how much voltage is generated by moving the
coil.
With
these exact measurements and the known equivalence of electrical
and mechanical power, NIST’s kilogram team relates mass to
electrical units.
Media
Contact:
Philip
Bulman, (301) 975-5661
Time
and Frequency
A Notary
Public for the Digital Age
Traditionally,
when you need a document authenticated, you take it to a notary
public, a person licensed to affix an official seal, date and
signature to it. But what about electronic documents or files?
Thanks to National Institute of Standards and Technology (NIST)
physicist Judah Levine, there may soon be a solution.
Levine,
a researcher in NIST’s Time and Frequency Division, recently
received a patent (no. US 6,393,566 B1) for a system that applies
a signed time stamp to any digital file, proving that it existed
at a certain date and time in a specific form. The time stamp
in the signature is traceable to the NIST time standard. Any
user can verify the authenticity of the file and its time stamp.
The authentication procedure does not require NIST participation,
and NIST does not need to maintain a copy of the original file.
If the file or original NIST time stamp have been altered in
any way since the NIST signature was applied, the authentication
process will fail.
Among the
many situations where the NIST electronic time stamp might be
used are the processing of time-critical commercial transactions
such as bills of sale or legal matters such as contracts and
wills. It also may be used to establish authorship and date
of creation for digital audio and digital video recordings,
and to support services similar to registered mail with return-receipt
requested.
Media
Contact:
Fred
McGehan (Boulder), (303) 497-7000
Technology
Partnerships
ATP
Project Helps Solar Energy Home Operate on Ribbons
In
a new twist on the American dream, a “Zero-Energy Cottage”
demonstrates how a homeowner might do away with those pesky utility
bills.
The
160-square-meter (1,700-square-foot), two-bedroom, two-bath house
features a number of environmentally friendly features including
solar electric panels made by Evergreen Solar of Marlboro, Mass.
The company developed an innovative approach to making its technology
with co-funding from the National Institute of Standards and Technology
(NIST) Advanced Technology Program.
Evergreen
Solar makes solar panels—which convert sunlight to electricity—using
a patented “String Ribbon” technique. Ultrathin crystalline
silicon is produced directly from molten silicon, a streamlined
process that avoids the waste and cost of slicing solid material
blocks. String Ribbon yields more than twice as many solar cells
per pound of silicon as typical methods, according to the company.
The
three-year ATP project overcame significant technical challenges,
including development of an active after-heater concept for precise
control of thermal gradients and stresses in the silicon as it
is formed and cools. Ribbon thickness was reduced from 300 micrometers
(0.012 inch) to less than 100 micrometers (0.004 inch), while
the width was doubled to 8 centimeters (about 3 inches). These
thinner, wider solar-grade ribbons also can be grown faster with
the after heater.
Media
Contact:
Jan
Kosko, (301) 975-2767
Law
Enforcement
NIST
Helps Make Criminal Hard Drives Become ‘Hard Evidence'
The
information technology revolution has changed how we do practically
everything. Unfortunately, it also has changed how criminals make
our lives miserable, with crooks using computers to commit fraud,
steal identities and even lay the groundwork for kidnapping. Fortunately,
a project in progress at the National Institute of Standards and
Technology (NIST) soon may help law enforcement agencies turn
the tables on these felons using their own computers.
The
clues for piecing together the acts of the computer-assisted crime
are often lurking deep in the criminal’s computer hard drive.
Law enforcement officers must acquire the contents stored there
before an investigation can take place. This is accomplished through
the use of “image tools”—automated software programs
that make an exact replica of the information or files stored
on the hard drive.
Increasingly,
defense attorneys are challenging image tools in the courts by
arguing that the product does not work as advertised. There have
even been claims that image tools actually alter the com-puter
files during the imaging process.
Computer
scientists at NIST have set up a testing program that evaluates
image and write blocker software to precisely assess how well
these tools function. The goal of the Computer Forensic Tool Testing
project is to provide the law enforcement agencies with the documentation
they need to assure that recovered digital evidence stands up
in court.
The
Computer Forensic Tool Testing project is funded by the National
Institute of Justice, the research arm of the Justice Department,
and managed through NIST’s Office of Law Enforcement Standards.
Media
Contact:
Philip
Bulman, (301) 975-5661
NIST
‘Hot' Movies Help Optimize Sensors
It
will never run in theaters, but this colorful movie has a cult
following all the same.
The
“thermal contour” movie reveals what happens to a microhotplate—a
National Institute of Standards and Tech-nology (NIST)-developed
technology that shows promise for a variety of gas-sensing applications—when
it is heated and cooled. The devices are attractive for use in
low-cost gas sensors, which might be used, for example, to detect
freshness of food products or the leakage or presence of harmful
chemicals.
The
small size and fast heating speed of these tiny, micromachined
devices pre-viously made it difficult to measure dynamic temperature
distribution, so NIST researchers use a new high-speed transient
thermal imaging system (originally developed by NIST to study
heating in power semiconductor devices) to make the movies.
The
imaging system collects temperature information every microsecond
for each 15 micrometer (0.006 inch) square of space on the microhotplate.
The system works by successively acquiring temperature response
as a function of time at each coordinate of the device being tested,
and by using a coordinate-translation scheme to move between points.
The thermal responses at different points are reconstructed to
make the thermal contour movie.
Media
Contact:
Michael
E. Newman, (301) 975-3025
Electricity
New NIST
Measurement System May Help Save Power and Dollars
Thanks
to the National Institute of Standards and Technology (NIST),
manufacturers of transformers used in the transmission and distribution
of electric power now will be able to meet proposed federal regulations
for efficiency that should yield dramatic energy savings.
The
U.S. Department of Energy (DoE) has mandated the labeling of energy
efficiencies on electrical appliances for years. In a similar
action, DoE is proposing high-efficiency standards for some transformer
equipment to reduce the amount of electrical energy lost as heat
in the transmission of electrical power from the generating plant
to the consumer. Studies estimate that these regulations ultimately
could result in an annual savings of several hundred million kilowatt-hours
and several million dollars.
With
the new regulations, transformer manufacturers must achieve compliance
while keeping production costs down. Additionally, a number of
smaller manufacturers are concerned about their meager budgets
for testing and a lack of measurement expertise necessary to demonstrate
compliance. NIST, collaborating with the industry, has alleviated
those problems with the development of a specialized power loss
measurement system needed for testing transformers. The system,
controlled by a laptop computer, precisely measures the electrical
input and output and determines the small differences between
them—the amount of energy lost in the equipment.
A
key conclusion of the research: high-precision testing can be
done with portable equipment made inexpensively with off-the-shelf
components.
In
addition to developing the power loss measurement system, NIST
partnered with the National Electrical Manufacturers Association
(NEMA) and DoE to develop the standard procedures for its use.
NIST soon will make the complete measurement system specifications
available to manufacturers so that they can make and use the testing
equipment in their own plants.
