New Model Tracks Smoke Plumes

"Where there's smoke there's fire" is the adage. But for NIST that's just part of the story. Smoke, itself, can obscure visibility and be a concern to populations downwind of a large fire. NIST fire researchers have created a computer-based model to predict the downwind distribution of smoke particulate and combustion products from large outdoor fires.

The program, called ALOFT-FT (A Large Outdoor Fire plume Trajectory model-Flat Terrain), also enables users to estimate smoke concentrations anywhere from ground level to the top of the plume. ALOFT-FT, which can be run on a Windows-based personal computer, requires as input data wind speed and vari ability, atmospheric temperature, and the size and number of fires. Results can be displayed as downwind, crosswind, and vertical smoke concentration contours. NIST developed ALOFT-FT to aid in the planning process for intentional burning of crude oil spills on water.

The program also can be used in predicting the smoke plume trajectories from other large outdoor fires such as those caused by burning structures. ALOFT-FT is available on the World Wide Web at http://fire.nist.gov/aloft/aloft-ftdownload.htm. The PC model is for smoke plumes blowing over flat terrain.

Contact: Doug Walton, (301) 975-6872.

Polarized Light Improves Displays

Elsicon Inc. of Wilmington, Del., has demonstrated an optical technology for aligning liquid crystals that is expected to increase manufacturing yields of liquid-crystal displays for laptop computers and many other applications.

With co-funding from NIST's Advanced Technology Program, Elsicon designed a generic technique using polarized light to align the liquid crystals that are the active elements in LCDs. In order for LCDs to function properly, adjacent crystals in the display must be lined up in the same orientation, just as magnetic poles are aligned in magnetized metals.

In the past, the manufacturing yields of liquid-crystal displays used in laptop computers, calculators, video games, instrumentation, and emerging high-definition television systems have been low. The low yields are attributable, in part, to an alignment technique that relied on physically rubbing the LCD screen. Elsicon's method relies instead on a new polymeric material with crystals that align automatically when exposed to polarized light. The company has applied the same approach to optical storage media for information storage devices.

The company is now working with several major LCD manufacturers to incorporate the new technology into factory processes and has received a $1.65 million contract from the U.S. Display Consortium to help in developing a scaled-up manufacturing process. Consumers are expected to benefit eventually from reduced LCD costs and improved viewing angles.

Contact: Shao-Tang Sun, (302) 478-2680, ext. 14.

Composite Towers Offer Cost Savings

The promise of composite materials is turning into a practical reality that could be worth billions of dollars to U.S. companies and consumers thanks in part to an affordable system for making composite structures designed with support from NIST's Advanced Technology Program.

With ATP co-funding, Ebert Composites Corp. of San Diego has designed and demonstrated a manufacturing system that has reduced production time for making composite transmission towers by 90 percent. The nine-person company substantially reduced manufacturing costs through two types of innovations: the towers are designed with interlocking joints for "snap and build" assembly that eliminates the need for adhesives, bolts, or other conventional fasteners; and a new manufacturing process was developed that combines pultrusion with "inline" computer numerical control machining.

Pultrusion is a process in which fibers are impregnated with a liquid resin and pulled through a heated die, which shapes and hardens the part. The ATP funding was used to design a CNC work station with a 5-axis machining head that performs intricate detailing on parts as they exit the pultrusion die. Designs for different parts can be stored in the computer and produced with high accuracy in any quantity and sequence without interrupting the process.

Southern California Edison Co. operates three Ebert demonstration towers near the Pacific Ocean. SCE has found that the structures cost about the same as steel initially but can be installed in one day instead of three and each tower costs $700 less per year to maintain. SCE expects the towers to last about 80 years, twice the life span of steel and wood. The new towers also weigh only one-third as much as steel, so they can be placed on-site by helicopters without the need to build roads.

Many other organizations, including a New Zealand utility and firms in other industries, have expressed interest in using the composite structures or the CNC machine.

Contact: Walt Warner, (619) 232-1270.

Tiny Portals to DNA Sequencing

Technologies to decipher patterns in DNA, the biological molecule that codes for an individual's genetic makeup, are faster than they used to be. But they still take hours and involve multiple steps and sophisticated laboratory equipment.

A team of scientists at NIST, Harvard University, and the University of California at Santa Cruz are now exploring a possible new way of reading a strand of DNA that is potentially much faster than existing techniques. The scientists are developing a system that forces single-stranded DNA through a tiny portal in a thin lipid membrane.

As shown in the graphic above, the system monitors the passage of an individual, negatively charged DNA molecule through a single nanometer-scale pore. The investigators apply a voltage across the membrane which forces the DNA strands through the hole. As the DNA moves through the pore, it partially blocks the ionic current flowing through the pore. Monitoring the length of time that the current is disrupted allows the researchers to determine the length of the strand.

The scientists suggest that it also might be possible to use this system to identify single bases, the "letters" in the genetic code, within long stands of DNA. This could be realized if each base causes a unique change in the current flowing through the pore. There are many technical hurdles to overcome before the system could have practical applications. However, if successful, the time to sequence DNA could be reduced substantially.

Contact: John Kasianowicz, (301) 975-5853.

Cracking Up Over Dental Drilling

The sound of a dental drill alone is enough to give most people goosebumps. Unfortunately, it may also be giving them subsurface cracks in their teeth. With funding from the National Institute of Dental Research, NIST researchers recently completed a collaborative study of drilling damage to teeth during preparation with diamond-impregnated cutting tools or "burs." Conducted with researchers from the University of Medicine and Dentistry of New Jersey, the Naval Dental School, and the University of Maryland at Baltimore, the study found that removing tooth enamel with a coarse diamond bur produced subsurface cracks as long as 50 micrometers to 110 micrometers. Coarse burs also produced a large number of smaller microcracks that, combined with the longer, vertical cracks, may make drilled teeth more susceptible to fracture. (See photo above.) The research found that fine diamond burs made with smaller diamond particles were effective in removing damaged areas caused by the coarser burs.

Dentists routinely use coarse burs to remove tooth decay and prepare a tooth for filling. To avoid possible problems from subsurface cracking, the researchers concluded that dentists should use a coarse diamond bur only for partial drilling and then finish the job with a finer diamond bur.

Contact: Said Jahanmir, (301) 975-4525.

Service Sector Technology Needs

Service sector spending on information technology has paid off handsomely, yielding an estimated return of nearly 200 percent. Yet, the complexity of computer networks, fear of being saddled with obsolete technologies, and other issues breed indecision that causes substantial underinvestment in new technology sectorwide. These and other findings are reported in a new NIST-sponsored study of the sources and uses of advanced technology in the service sector--by far the largest and fastest growing segment of the U.S. economy. Commissioned by NIST to help guide its strategic planning, the study reviews a range of economic data and contains case studies of technology trends in the retail banking, home entertainment, and health care industries.

For the sector as a whole, information technology accounts for more than 80 percent of technology spending. Spending on research and development has increased in recent years, but the sector primarily imports its advanced technology from other industries.

The study, performed by TASC, Inc., identified 19 technology needs and issues common to two or all three industries that were studied indepth. These include support for electronic commerce applications, cryptographic standards, internet-based tools, network scaling, data compression, and wireless communication.

To request a single copy of The Economics of a Technology-Based Service Sector, (NIST Planning Report 98-2), contact Denise Herbert at (301) 975-2657. The text is also available on the WWW at www.nist.gov/director/prog-ofc/report98-2.pdf.

Physicists Build Quietest of Places

Want to get away from it all? We've found the quietest place on Earth, literally.

Researchers at JILA, a joint institute of NIST and the University of Colorado, are building the most vibration-free platform on Earth. The structure is being built to measure things like "thermal noise," that are normally unmeasurable due to even the slightest mechanical vibration. It also will make possible the ground-based detection of low-frequency gravity waves coming from the cosmos.

The instrument uses three nested platforms hung on springs, each with six sensitive movement sensors and non-contact magnetic pushers. The sensors detect the slightest vibration and high-speed electronics activate the magnetic pushers to move the platform in the opposite direction and cancel the vibrations out. The system is designed to be effective at canceling out low-frequency, long-wavelength vibrations that are normally very difficult to eliminate. The system is so sensitive that vibration in even a quiet room can be reduced by a factor of nearly a million.

The principles used to build the new platform also may be applicable to industrial processes like fabrication of ultra-small integrated circuits or diamond turning of super-smooth surfaces.

Contact: James Faller, (303) 492-8509 or Joseph Giaime, (303) 492-0448.

Cookies, Pigs, and Profits

Babe and his friends will be awfully disappointed with Interbake Foods' scrap reduction program. Interbake is one of two manufacturers licensed to make the perennially popular Girl Scout cookie. One particular cookie--the Carmel deLite--makes up about half of the plant's Girl Scout cookie volume. It's also the hardest to make. And anything not up to specs gets tossed into a bin for eventual shipment to some lucky farm critters. In 1995, Interbake's management decided to take a hard look at the waste produced by its baking lines. The Virginia-based commercial baker learned about the pollution prevention grant program offered by Virginia's A.L. Philpott Manufacturing Extension Partnership--an affiliate of NIST's Manufacturing Extension Partnership. A matching grant helped Interbake buy computers to monitor bins of rejected cookies. Production workers also have started pulling samples for inspection every 15 minutes. Interbake's scrap reduction effort yielded savings of about $290,000 during its first year, and the matching grant has been extended for a second year. Contact: A.L. Philpott MEP, (540) 666-8890.

Some REALLY Skinny Standards

In an effort to keep up with the galloping pace of change in the semiconductor industry, NIST has teamed with VLSI Standards Inc. of San Jose, Calif., to improve the availability of thin-film reference materials tailored for industry. Through a cooperative R&D agreement, NIST worked with VLSI Standards to establish traceability to NIST standards for the company's new 4.5 nm and 7.5 nm (billionths of a meter ) thin-film reference materials. Made of silicon dioxide, these thin films are needed by the semiconductor industry to calibrate ellipsometry instruments used for process development and process quality control when making very large-scale integrated circuits. NIST enabled the company to establish its measurement "traceability" by carefully characterizing the company's thinnest reference materials with NIST's primary, high-accuracy ellipsometer. Currently the thinnest silicon dioxide Standard Reference Materials available from NIST are 10 nm thick, provided on wafers with 76 mm (3-in.) diameters. The company's new reference materials will be provided on 150 mm (6-in.) and 200 mm (8-in.) diameter wafers now more common in industry. Contact: Barbara Belzer, (301) 975-2248, or Prabha Durgapal, (408) 428-1800.

Lighting the Way to Safer Flying

Air traffic controllers do an amazing job keeping aircraft safely separated. Nevertheless, as a last line of defense pilots rely on good old fashioned visual sighting to avoid collisions. To make planes more visible--especially at night and during bad weather--the Federal Aviation Administration requires that planes have red or white flashing anticollision lights with a minimum intensity of 400 candelas. Accurately measuring intensity for a flash that lasts only a split second, however, turns out to be fairly tricky. Field intensity measurements of anticollision lights on commercial aircraft have differed by as much as 30 percent, indicating a critical need to develop a calibration standard for such measurements. Through a two-year research study funded by the FAA, NIST physicists came up with a system that uses two independent calibration methods to produce a primary standard photometer system with an uncertainty of only 0.6 percent. They hope a new calibration service and recently agreed upon standard measurement methods will improve uncertainty for field measurements to less than 10 percent. Contact: Yoshi Ohno, (301) 975-2321.

Clock in S ... P ... A ... C ... E

NASA has awarded a research grant to NIST to develop an atomic clock for placement on the International Space Station in five to seven years. The performance of atomic clocks depends on how long individual atoms can be observed. In microgravity, the observation time can be increased by a factor of 10 or more, and NIST projects the accuracy of the space clock will be at least 10 times better than the best Earth-bound clocks. Researchers will use it to perform a variety of tests of important physics theories and to study the orbits of Global Positioning System satellites, which could lead to improved accuracy for certain applications, such as surveying. Contact: Steven Jefferts, (303) 497-7377.

Improving Production -- A small San Francisco bedroom furniture manufacturer recently worked with the Northern California Corporation for Manufacturing Excellence or MANEX (an affiliate of NIST's Manufacturing Extension Partnership) to better meet its production demands cost-effectively and on time. MANEX designed a customized training program for The Futon Shop that helped the firm's own employees identify waste and develop a new inventory and assembly system. The improvements helped the company increase overall production by 30 percent, eliminate more than $100,000 annually in waste, and save $20,000 per month in payroll costs. Contact: MANEX, (510) 249-1480.

Optical Properties -- NIST is inviting companies to join a new consortium on optical properties of materials. Organized in response to requests from industry, the National Aeronautics and Space Administration, and the Department of Defense, the consortium will address critical needs for high-accuracy optical measurements, new standards development and evaluation, and dissemination of optical properties of materials data. The consortium's goal is to provide information that will help reduce manufacturing cost and improve product quality for both military and civilian markets. Contact: Raju Datla, (301) 975-2131.

Tiny Freezer -- The next space shuttle mission, scheduled for April 1998, will carry a tiny freezer with a big job to do. Designed, built, and tested under an agreement between NIST and Lockheed Martin Astronautics of Denver--with significant contributions from NASA Ames Research Center--the freezer is the world's smallest "pulse tube refrigerator." Its job is to cool infrared sensors and other devices to temperatures of 80 kelvin (-315 degrees F), so scientists can collect accurate data on temperature variations in the atmosphere and oceans. These data are needed for studies of the ozone hole, global warming, and long-range weather forecasting. The device itself has no moving parts near its cold tip, is about 12.5 cm (5 in.) long, and weighs less than 1 kg (2 lbs.). Associated batteries, control electronics, and an onboard computer for recording temperature data weigh about 100 kg (200 lbs.). Contact: Ray Radebaugh, (303) 497-3710.

About Technology at a Glance:

NIST is an agency of the U.S. Department of Commerce's Technology Administration. NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements, and standards. Technology at a Glance is produced by Public and Business Affairs, A903 Administration Bldg., NIST, Gaithersburg, Md. 20899-0001. Any mention of commercial products is for information only; it does not imply recommendation or endorsement by NIST. Technology at a Glance Editor: Gail Porter, (301) 975-3392, email: gail.porter@nist.gov. For patent information, call (301) 975-3084.

Technology at a Glance Archive Files