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July/August 2002

  In This Issue:
bullet NIST Researchers Approach Non-Physical Standard for Kilogram
bullet A Notary Public for the Digital Age
bullet ATP Project Helps Solar Energy Home Operate on Ribbons
bullet NIST Helps Make Criminal Hard Drives Become 'Hard Evidence'
bullet NIST 'Hot' Movies Help Optimize Sensors
bullet New NIST Measurement System May Help Save Power and Dollars
bullet Tech Trivia

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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



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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) 497-7000Up


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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) 975-2767Up


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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



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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) 975-3025Up


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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.

Media Contact:
Philip Bulman,  (301) 975-5661Up


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Tech Trivia

In 1973, the American Society of Mechanical Engineers asked the National Institute of Standards and Technology (NIST) to help them help municipalities better dispose of combustible waste. NIST burned statistically selected samples of trash to evaluate the range of combustion temperatures and the types of pollutants released. NIST scientists also provided thermodynamic data for more than 1,300 substances commonly found in municipal waste.

Also in 1973, NIST helped electric utilities better avoid power outages. The transmission of electrical power can be severely affected by transient currents on the lines, sometimes leading to blackouts. Shunt reactors, large devices similar to transformers, can “tune out” transients and stabilize power flow. A NIST-developed high-voltage capacitance bridge provided the first accurate measurements of power losses accompanying shunt reactor installations, and permitted a NIST calibration service for the devices to be established.

In 1974, NIST energy-conservation researchers estimated the fuel consumption of automobiles in terms of the types of vehicles and the characteristics of the roadways involved. Travel on expressways, arterial roads and local streets was considered, with the gas usage varying according to operating conditions. The study’s authors concluded that such basic data could be used by urban planners to design transportation grids for maximum energy consumption.

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Editor: Michael E. Newman

Date created: 08-27-02