The Cutting Edge: COMPUTING / TECHNOLOGY / INNOVATION : Custom-Warming With High-Tech ‘Earmuffs’
For more than a decade, Ival Salyer, senior research scientist at the University of Dayton Research Institute, has been working on a material that, embedded in wallboard or concrete, would in winter absorb excess heat during the day and release it at night, and do the opposite during the summer. The principle is simple: When materials change from a solid to liquid or from liquid to gas, they absorb heat from their surroundings, much like a melting cube of ice. Energy is released when the process is reversed.
But it turns out that the greatest successes Salyer has enjoyed from his patented “phase-change materials” (PCMs) have come from spinoffs that have nothing to do with heating or cooling houses. Under an agreement with Phase Change Laboratories in San Diego, for example, R. G. Barry Corp. in Pickerington, Ohio, has introduced a line of microwaveable earmuffs, scarves and hand warmers. Sold under the Dearfoams brand name, the garments are made with a powder form of one of Salyer’s phase-change materials.
Phase Change Laboratories is marketing Powder Paq hot and cold compresses to medical supply houses. Other companies have expressed interest in using PCMs to prevent overnight freezing of highway bridge decks and citrus tree trunks, and in encapsulating them in clothing as insulation. U.S. Gypsum Co., the world’s largest producer of wallboard, has offered to conduct a production run to demonstrate the feasibility of making PCM wallboard, but the trial has been delayed because of the cost of producing the PCM pellets.
Light Speed: Fiber-optics technology, in which hair-thin glass fibers carry enormous amounts of information, has for years been making many types of communications faster, cheaper and clearer. Now engineers from Corning Inc. and the University of Rochester have built and tested a new type of fiber that solves some of the limitations of existing fiber and might eventually be able to carry far more data.
Optical communications depends upon sending billions of light signals a second: The signals are encoded with representations of everything from telephone conversations to video. The closer together the signals can be sent without blurring, the more information a fiber can carry. Think of someone standing on a hill flashing signals with a mirror. At a certain point, the flashes come so rapidly that they appear to be one continuous flash.
The problem is that different pieces of the light spectrum (which we see as different colors) travel at different speeds. So if the pulses of a regular laser light aren’t placed far enough apart, they can blur together, destroying the information. This is especially true if the pulses are being sent over long distances.
Scientists have attacked this problem in a number of ways. Several companies, including AT&T; and Japan’s Nippon Telephone & Telegraph, have tried to reduce the blurring using solitons, a special type of light wave that doesn’t change shape as it travels. But even these ultrashort solitons have dispersion problems: Their energy drops as they travel down fibers. Boosting their energy makes the solitons unstable.
So Corning built a tapered fiber to compensate for these energy fluctuations, matching the soliton’s decreasing energy with a fiber whose dispersion decreases proportionally. Andrew Stentz, a graduate student at Rochester, built a soliton laser and sent its one-picosecond light pulses, dozens of times faster than those used in today’s fiber systems, through a 40-kilometer (24.8-mile) stretch of fiber. The solitons emerged intact. When Stentz sent solitons from the same laser through conventional fibers, the signals quickly degraded.
Smart Wings: Tiny silicon “flaps,” each less than a millimeter square, may one day be used to reduce the drag on airplane wings, resulting in huge savings in fuel costs. Normally, micro-machines like these flaps are used to control other small devices. But a team of researchers from UCLA and California Institute of Technology this week described to the American Physics Society in Atlanta just how micro-machines could control something as large as a jet aircraft.
By distributing a system of thousands of pin-head-sized silicon flaps on the wings of an aircraft, the entire area covered would become a “smart” control surface.
The suction created by the vortices of air that flow across the top of the wing provide a significant part of the lift force. Placing the flaps at critical points on the wing’s leading edge would efficiently control the air flow over the wings during flight, thus saving fuel.
The flaps would be controlled by on-board computers using a set of vortex turbulence algorithms developed at UCLA. Because this technology could be adapted to aircraft of any size, it could be used, for example, on the hotly anticipated Mach 2 High Speed Civil Transport being developed by the Air Force.
