Technology bulletin 23334Technology bulletin 23334

New material for space mirrors and telescopes

Researchers at Sandia National Labs and the University of Kentucky are developing the enabling technology for a mirror made from a new thin film. The film is a piezoelectric material-polyvinylidene fluoride-that is inexpensive, readily available, and exhibits the necessary properties. Potential applications for this thin film could include the development of improved space telescopes and surveillance satellites. "Unlike the Hubble telescope and NASA's upcoming Next Generation space telescope which use a traditional polished glass mirror approach, the new approach uses the lightweight thin film. The thin film folds up and could be carried on a small booster rocket, then opened to its full diameter while in orbit," says Tammy Henson, the principal investigator. The material changes shape when struck by electrons fired by a computer-controlled gun. "The electronic gun corrects the shape of the film mirror to its desired form to within ten-millionths of an inch, which is the required accuracy for optical quality imaging applications," says Henson. Contact Henson at [email protected] or call (505) 844-2405.

Smart antennas for the wireless web

Smart antennas may be critical in preventing Internet traffic jams as an increasing number of people use wireless devices for downloading files from the Web, according to Michael Zoltowski, an electrical engineer and professor in Purdue University's School of Electrical and computer Engineering (West Layfayette, IN). The smart antennas are a combination of two or more antennas working together which outperforms conventional single antennas the same way two ears outperform one. Smart antennas work better than conventional antennas because cellular communication relies on base stations that provide service to separate regions called cells. The cells are arranged in a honeycomb pattern spanning large geographical areas. Performance in these systems is hindered by two types of interference that disrupt the code division multiple access (CDMA), a technique in the wireless business that makes possible the simultaneous operation of multiple users on a single frequency. One type of interference is caused by signals bouncing off buildings or mountains on their way to and from base stations. The other type of interference in CDMA systems occurs while the user approaches the boundary of two adjacent cells and has to be "handed off" from one base station to another. Having more than one antenna helps eliminate both types of interference because it allows the receiver to distinguish between the two base stations'signals arriving from different locations and different directions. "It works in much the same way that having two ears allows us to determine from what directions sounds come," says Zoltowski. He says that switching from conventional technology, called Rake receivers, to a new technique that uses timing and sequences of codes to transmit data would enhance the performance of wireless systems. "Using a technique called space-time equalization and equipping wireless devices with more than one antenna would increase the number of users operating simultaneously in each frequency band," says Zoltowski. "We still need to refine the circuitry more," he cautions. "However, we do have some companies that are developing confidence in our concepts," he says. Texas Instruments is testing a cell phone with two antennas. Contact Zoltowski by calling (765) 494-3512, faxing (765) 494-0880, or emailing [email protected] .

Building better lasers

Researchers Peter Veitch and Murray Hamilton are using a series of linked laser diodes for powering a stable, infrared laser that is based on a garnet crystal doped with rare-earth neodymium. The two researchers work for the University of Adelaide in Australia. Their research involves identifying dark matter in space. Detecting dark matter is a difficult task because it emits almost no electromagnetic radiation. Gravitational waves offer another means of analyzing dark matter, according to Veitch and Hamilton, but detecting gravitational waves is also difficult. Vietch believes laser-based detectors offer a suitable solution. "The aim of our work so far has been to demonstrate that there is a better technology for producing efficient, high-power stable Nd:YAG lasers that produce diffraction-limited beams," says Veitch. "Such a laser would be useful for deep-space communications and non-linear frequency con- version," he says. Additional applications include remote sensing and possibly military counter measures. Contact Veitch at [email protected] .

Breakthrough in automotive fuel cells

Fuel cells are one key to high mileage, zero-emission automobiles. A fuel cell uses hydrogen for producing electricity with water being the only emission. Development of a bipolar plate at the Oak Ridge National Lab (ORNL) could make fuel-cells practical for use in cars, according to Theodore Besmann, head of the team at ORNL that developed the plate. "The significant and growing interest in fuel cells for stationary power and transportation applications has been demonstrated by the attention these technologies are receiving from both government and industry, and particularly from the automotive companies," says Besmann. The ORNL bipolar plate is important to the technology of choice for the automotive industry because of its low-temperature operation and rapid start up. The ORNL plate overcomes significant fuel cell barriers such as weight, cost, corrosion resistance, conductivity, and manufacturability. It uses a carbon composite that is fabricated by slurry molding an unidentified chopped fiber. The slurry is sealed with vapor-infiltrated carbon using methane as the precursor in the process. The resulting component is hermetic and has a high electrical conductivity. Cell testing of an active area in a single-sided plate indicated very low cell resistance and high efficiency. However, there was a steep drop off in voltage with current at high values, according to Besmann. The material also has a low density, which makes it lightweight-about half that of other potential fuel cell materials. Contact Besmann at [email protected] or call (865) 574-6852.

Students' invention makes hand guns childproof

Bryan Rydingsward and Richard Glorioso designed a device that makes handguns much safer. Without relying on electronics, keys, or combination locks, the safety device works by covering and manipulating the safety lever. In tests conducted at Johns Hopkins University (Baltimore, MD) where Rydingsward and Glorioso graduated with degrees in mechanical engineering, children up to age seven could not defeat the device. "We intentionally tried to stay away from high-tech devices. After brainstorming, we started looking at simple devices that work to protect children, like the caps on Tylenol bottles," says Rydingsward. Rydingsward and Glorioso's device is a low-tech approach that uses simple springs and mechanical devices. It mounts on the pistol's barrel, covering the safety lever and forcing it into the position that prevents the gun from firing. When the two buttons are depressed, the cover slides open exposing the safety switch and allowing the user to put the gun into the firing mode. Small children lack the dexterity, finger strength, and mental agility to open the sliding door. The children's mothers were able to open the device in three seconds. "You could open the cover and flip the safety lever with your eyes closed," says Glorioso. For adults, opening the device quickly is an important feature because gun owners would want to arm themselves quickly if an intruder entered their home. Another feature of the device is its passive protection. It doesn't require the gun user to do anything other than put down the gun to reactivate the safety, which is done automatically. The students and their professor, Dr. Andrew Lincoln, estimate the cost of equipping guns with the device to be approximately $35. They applied for a patent in May and are seeking inquiries from manufacturers. Contact Johns Hopkins University at (410) 516-7160 or send faxes to (410) 516-5251.

Biodegradable polymers

Dow Chemical and Cargill Inc. are building a new facility in Blair, NE, for processing corn-derived dextrose into biodegradable polymers. Replacing non-degradable plastics with biodegradable polymers reduces the burden on landfills. The plant's 100 employees will produce the polylactide polymer from corn's natural plant sugars. The finished product is spun into fibers that are used in personal care products, clothing, compostable packaging, and other products. The new technology was developed with the National Institute of Standards and Technology under their advanced technology program. For more information on the polymer, call Linda Schilling at (301) 975-2887 or go to www.cdpoly.com .