Developments to Watch
DIVIDING AND CONQUERING AUTO EMISSIONS
CATALYTIC CONVERTERS HAVE been remarkably successful in reducing auto emissions. But the Environmental Protection Agency is looking for improvements. Starting with the 1996 model year, the EPA will require a dashboard warning light that indicates catalytic converter malfunction. Also, this summer, the agency will issue a rule regulating "command enrichment"--the delivery of extra fuel to help cool an accelerating engine, at the cost of a huge jump in carbon monoxide emissions.
Taking a different approach to cleaning up exhausts, the Energy Dept.'s Argonne National Laboratory has devised a system that captures air and uses a membrane to divide it into two streams, one rich in oxygen and one rich in nitrogen. The oxygen-rich stream flows into the engine. That helps the fuel burn more completely, but it also creates extra nitrogen oxide emissions. To remedy that, the nitrogen-rich air stream is fed to the exhaust. There a spark plug breaks up the nitrogen molecules. They react with nitrogen oxides to form harmless nitrogen and oxygen. Argonne says the system cuts nitrogen oxide emissions by more than half.
Corning Inc. has also made a contribution to auto-exhaust cleanup. It has developed a so-called zeolite to soak up exhaust gases that would otherwise escape before the catalysts are hot enough to kick in and cleanse them. Corning says the spongelike mineral helps slash hydrocarbon emissions to below the ultralow-emissions vehicle standard for 2000.EDITED BY OTIS PORTReturn to top
NO CHINK IN THIS CERAMIC ARMOR?
FIVE YEARS OF WORK HAS YIELDED A CERAMICS BREAK-through--a material similar to what's used for dinner plates, but so tough it may end up as armorplate on tanks. "We're also looking at pistons and turbines" for auto and jet engines, says the material's developer, William W. Predebon of Michigan Technological University in Houghton. Another possible use: Industrial cutting tools that easily chew through high-strength metals.
The secret of the new alumina ceramic? Predebon took things out of the usual ceramic mix. Ceramics are difficult to process, so they normally contain sintering aids to help hold the ceramic mix together. But when Predebon inspected ceramic fractures under a microscope, he noticed the breaks often occur in the sintering additives. So he removed that weak link by developing a new processing method, using a hot vacuum press, that doesn't need additives.
The resulting material is so tough it doesn't break until he applies 50% more pressure than alumina ceramic is supposed to tolerate. Under normal conditions, it can withstand almost as much pressure as tungsten-carbide steel, one of the strongest materials around. And under high loading--such as extreme pressure from the impact of an artillery shell--the ceramic's toughness actually increases, beating tungsten-carbide steel by 37%.EDITED BY OTIS PORTReturn to top
REAL LESSONS FROM A PSEUDOTUTOR
IF HERMAN AND HIS KIND can live up to the initial raves of students at Martin Middle School in Raleigh, N.C., teachers will soon be getting help from pseudospace. A bug-like alien dreamed up by researchers at North Carolina State University, Herman is just a computer simulation, but a savvy one.
He's a tour guide for the Design-A-Plant program. To teach botany to children aged 9 to 14, Herman takes them to four planets and explains the different ecologies. Then Herman challenges each student to devise a plant suited for that planet. By analyzing the responses to periodic questions, Herman's artificial-intelligence component sizes up its human students and adjusts the interactive presentation accordingly. For families that can't afford a personal tutor, Herman the pseudotutor could be the next best thing.EDITED BY OTIS PORTReturn to top