Technology Bulletin

Atomic clock delivers highly accurate timekeeping

A new cesuim atomic clock under development at Westinghouse Electric Corp., Pittsburgh, promises to improve military and commercial communications and location systems. The patented device is much smaller, requires less power, and costs less than the elaborate atomic clocks now available commercially, say Westinghouse engineers. Although the clock is unlikely to become a general substitute for the tiny, inexpensive crystal oscillators widely used in electronic circuits, it could replace them in applications that require highly accurate timekeeping. The clock could be used to synchronize the transmission of multiple TV and other digitized signals over fiber-optic cables. "It will be one-tenth the size and 100 times lighter than any atomic time standard now available," says Irving Liberman, Westinghouse time standards program manager. Liberman estimates availability in '97. E-mail him at liberman@epsvax.pgh.wec.com .

All-terrain robot is designed to be expendable

NATO's mission in Bosnia has highlighted the dangers of hidden landmines. Now, engineers at Lawrence Livermore National Laboratory (LLNL), Livermore, CA, are collaborating with inventor Bill Wattenburg to produce a mechanical minesweeper that won't cost an arm or a leg--literally. The Spiral Tube All-Terrain Robot is designed to handle mud, water, or dry terrain and transport sensors to detect mines, hazardous waste, or other toxins. It climbs stairs and can go almost anywhere a foot-soldier can go, says Wattenburg. When fitted with video cameras and sensors, the 125-pound aluminum robot could be sent ahead of soldiers to sniff out enemy troops or to locate or detonate weapons, says Wattenburg. Developers predict the robot will cost $2,000 and may eventually be used as an expendable tool for risky law enforcement and intelligence-gathering maneuvers, or for planetary exploration. FAX Ms. Erna Grasz of LLNL at (510) 423-4606.

Laminated composites may benefit high-temperature parts

By applying alternating thin layers of matrix materials to traditional reinforcement structures, researchers at the Georgia Institute of Technology have developed a new type of material that they believe will be tougher than conventional fiber-reinforced composites. The "laminated-matrix" composites could replace metals in aircraft structural components, heat exchangers, particulate filters and other applications requiring high-temperature, high-strength materials, say engineers. They hope the materials will replace costly reinforcing fibers with less-expensive platelets or particles. The process uses a fibrous preform made of stacked layers of cloth. "We infiltrate with one material until we get a layer of it around each fiber, then we infiltrate with another material, then we switch back to the first," explains research scientist W. Jack Lackey. "We put down as many as 50 layers." Lackey notes that the matrix materials must be chemically compatible and closely matched in their thermal-expansion properties. E-mail Lackey at jack.lackey@gtri.gatech.edu .

New imaging technique lets MRI diagnose artery problems

Magnetic Resonance Imaging (MRI) may provide a non-invasive alternative to catheters and other methods of diagnosing serious problems in the arteries of the human heart. Standard MRI techniques can't produce sharp images of the coronary arteries because they require several minutes of exposure, and the patient's chest moves with each breath. The arteries are also difficult to distinguish from surrounding tissues. Now, a team of engineers at Stanford University think they have found a way to overcome these problems. Their solution changes the way images are gathered and processed--not the MRI hardware itself. The engineers created a "diminished variance algorithm:" a mathematical treatment of the image data that corrects for distortions caused by breathing. A second technique, called selective inversion recovery or SIR, uses radio waves to "tag" blood before it flows into the arteries. Conventional MRI equipment can then image just the tagged blood, making the coronary arteries stand out clearly. Clinical studies will determine the effectiveness of the new technique in diagnosing disease. For details, e-mail Albert Macovski at macovski@isl.stanford.edu .

CVD yields minuscule mechanical and optical parts

Engineers at Rensselaer Polytechnic Institute are using a laser and chemical vapor deposition (CVD) to build minuscule mechanical and optical parts that may eventually be used in surgical tools or the nozzle arrays of high-resolution printers. The micro-mechanical parts can only be seen by an instrument such as a scanning electron microscope. The 3-D shapes, such as a needle less than 5 microns wide at its tip, are formed as they are built up. The process uses a laser to heat a plate selectively, causing the desired material to deposit only in heated locations. A computer controls the position and orientation of the substrate as well as the focal point and power of the laser. The technique may allow engineers to build miniature parts of any of the materials used in conventional CVD, such as metals, intermetallics, ceramics, and some polymers. Parts could be formed of extremely high-temperature materials such as hafnium carbide, says project leader Joseph Pegna. E-mail Pegna at pengaj@rpi.edu .