Technology Bulletin

Looking at failures in a new light

Two Department of Energy researchers at Sandia National Labs are taking a new approach to the study of how and why engineered systems fail. Chris Forsythe and Caren Wenner say that, instead of looking at all the things a person might possibly do wrong, they study identifying conditions and environmental factors that make the potential for human failure probable. "Mitigating these factors enhances the surety of engineered systems, such as nuclear weapons," says Forsythe, a member of the lab's Statistics and Human Factors Department. "The standard technique for preventing error is an analysis that attempts to establish an exhaustive list of everything that is likely to go wrong," says Forsythe. "After you've done that a long time, you get good at it, but it can be labor intensive and you always miss some things. The problem that humans bring to systems is an infinite number of ways to fail. You can never anticipate all that can go wrong." The alternative method Forsythe and Wenner use is called an "organic" model. They believe that the introduction of humans into an engineered system causes the entire system to take on organic properties and that, to fully evaluate safety and security of a system, these properties must be considered. Contact: (505) 844-5720.

The big chill for computer chips

Michigan State University researchers believe their new material, a combination of cesium, bismuth, and tellurium, will someday double the speed at which computers operate. "We've demonstrated that the new material outperforms the current material in a given temperature range," says Mercouri Kanatzidis, a Michigan State University professor of chemistry in whose laboratory the discovery was made. Current thermoelectric materials drop their temperatures when jolted with electricity. The new material could drop the temperature even more. Eventually, its applications could include cooling computer chips. Currently, most computers use fans for cooling chips. According to the professor, fans will be insufficient. "As chips become smaller and more powerful, they generate more heat. We'll need a more active way of removing the heat," says Kanatzidis. The discovery stems from several years of research funded by a grant from the Office of Naval Research. Contact Kanatzidis at (517) 355-4512, ext 174.

Bright idea for flat-panel displays

Researchers Stephen Forrest and Marc Baldo from Princeton University with colleague Mark Thomson of the University of Southern California created a light-emitting material that they say improves the efficiency with which light is produced for flat panel displays found in laptop computer screens, car stereo displays, hand-held devices, cellular telephones, and elsewhere. The team combined the phenomena of fluorescence and phosphorescence in a way that allows the production of light that is four times more efficient than fluorescent materials. The result is an organic light-emitting diode (OLED) made of thin films that emit light. The efficiency of light-emitting devices depends on how well molecules react in "excited" states called "singlets" and "triplets." The material emits light when either singlets or triplets release their energy and return to a ground state. The researchers use phosphors to "collect" all the triplet states, convert them to usable singlets, and transfer them into fluorescent material. Princeton applied for a patent on the work. FAX: (609) 258-0119.

Optical switching faster than electronic

Optical transistors may soon offer designers greater bandwidth and speed than electronic transistors, according to Panos Datskos of Oak Ridge National Laboratory (ORNL). "We are talking about using photons instead of electronics and creating transistors that are 100 times faster than any of today's transistors," says Datskos. Electronic transistors are used today as amplifiers, detectors, and switches in computers, telephones, and many other electronics components. Optical switching by photon activation is analogous to a transistor with input photons controlling the signal photons. Datskos and colleague Slo Rajic use a highly sensitive miniature light detection device called a micromechanical quantum detector. The optical switching technology uses a diode laser and optical absorption of its wavelength. If enough stress is created by the absorption of the light, it puts a strain on the material. By shifting the wavelength, it turns the switch on an off. "It is similar to the electronic transistor, but incorporates the benefits of photonics," say Rajic. Call Datskos at (865) 574-6205.

Optical standards

Optical power meter users, such as designers of optical fiber telecommunications equipment, and compact disc player manufacturers may now obtain several papers from the National Institute of Standards and Technology (NIST) that pertain to measurement and calibration standards. The NIST Standards, known as Standard Reference Materials (SRM) fall into two categories for optical fibers: geometric properties and propagation characteristics. The standards allow description of a fiber based on either its physical dimensions or the way in which light propagates within it. For physical dimensions, NIST offers SRMs for fiber cladding diameter, fiber coating diameter, connector ferrule (for both inner and outer diameters), and mode-field diameter. In the field of propagation characteristics, available SRMs include chromatic dispersion, polarization- mode dispersion, and polarization-dependent loss. Copies of the paper "NIST Artifact Standards for Fiber Optic Metrology" (No. 03-00) are available from Sarabeth Harris at sarabeth@boulder.nist.gov or call (303) 497-3237. For more information on optical fiber artifacts and SRMs, contact Lee Best at le.best@nist.gov .

X-ray vision

A research team at the University of North Carolina at Chapel Hill and North Carolina State University developed a new x-ray imaging method called Diffraction Enhanced Imaging (DEI) that produces better pictures of breast tissue than conventional x-rays. "DEI conceivably could be used not only in breast imaging, but in any medical and non-medical applications involving x-rays," says Dale Sayers, professor of physics at NC State. Researchers there compared images and found tumor visibility was superior with DEI in six of the seven specimens. With DEI, an "analyzing" crystal is placed in the x-ray beam between the object being studied and an image-creating medium such as film, x-ray plate, or digital detector. The silicon crystal diffracts a particular wavelength of x-ray through the physics principle known as Bragg's law. When the crystal is adjusted and two images taken and processed, a new image based on refraction is produced. Refraction (where light, including x-rays, deviates in angles) happens because of differences in the atomic density of the materials through which it passes. "In a tissue sample, if a tumor is embedded in normal tissue there is usually a density difference that results in the defraction. The difference is detected and imaged and has now been shown to be more sensitive in some cases for features diagnostic of cancer," Sayers says. Contact Sayers at sayers@esrf.fr .

Technology spending up

The Commerce Department's $722 million technology budget for fiscal year 2001 is $77 million more than last year's budget, according to summary of appropriations issued by Commerce Secretary William Daley. The budget's initiatives include $60 million for the nation's information infrastructure by establishing the Institute for Information Infrastructure Protection (IIIP). The IIIP created a team of security experts that identify and fix vulnerabilities in information systems and prepare for security threats. An additional $14 million is devoted to expediting the transition to electronic commerce by increasing software interoperability and providing measurement techniques for characterizing microcircuits, interoperability standards, and test methods for wireless products. Almost $16 million is budgeted for strengthening science and technology infrastructure. Another $10 million is earmarked for developing the measurements and standards needed for nanotechnology. Spending for construction of research facilities dropped from $106,880,000 in FY 2000 to $35,879,000 in FY 2001. A FY 2001 Technology Administration Budget Highlight is available by faxing a request to (301) 926-1630. The detailed budget summary, supplemental fact sheets, and a budget process flow chart are available on the World Wide Web at www.ta.doc.gov .

World's first visual prosthesis gives gift of sight

Researchers at the Dobelle Institute (Zurich) say they have developed an artificial vision system that lets blind people identify objects from long distances, watch television, and use the Internet. The group found that stimulating the visual areas of the brain with information relayed from a camera to implanted electrodes allows blind patients to see flashes of white. In a demonstration, the researchers showed how a patient who has been blind for 26 years could navigate around a room and retrieve objects. The equipment consists of a sub-miniature television camera and an ultrasonic distance sensor. The camera is fixed, at eye level, to a pair of glasses worn by the patient so that images in front of his/her eyes match images picked up by the camera. The sensors, also mounted on the glasses, connect through a cable to a miniature computer, which is worn in a pack on the person's belt. After processing the video and distance signals, the computer uses sophisticated imaging technology, including edge-detection algorithms, to simplify the image and eliminate noise. The computer then triggers a second microcomputer that transmits pulses to an array of 68 platinum electrodes implanted on the surface of the brain's visual cortex. If a feed from a television or a computer is used instead of a feed from a camera, the user can detect images from those sources, too. According to the institute, the vision system enables a totally blind person to achieve visual acuity of 20/400 in a narrow visual "tunnel." The system will be commercially available in Europe this year. FAX: (212) 927-6300.