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Shifty Blades
Shape-shifting rotor blades could boost helicopters’ flight ranges and payload capacities. Designed by researchers at the U.S. Office of Naval Research, the Naval Air Systems Command, and Boeing, a new “torsional actuator” twists a rotor blade along its length like someone trying to pop ice cubes out of tray. The angle of rotation is no greater than two degrees in either direction, but the resulting shape change can customize the blade’s aerodynamics for either hovering or flying forward. Installed in the blade near the rotor hub, the actuator has a core made of NiTinol, a nickel-titanium alloy that deforms when subjected to an electric current. This deformation rotates a rod running through the blade; the rod in turn torques the blade. Calculations indicate that using such a blade instead of a fixed-shape blade could increase helicopters’ payload capacities by 40 percent. The actuator project is scheduled to be completed in 2008, after which the device could be retrofitted into existing vehicles.

Pixel Perfect
Get too close to your TV screen, and you’ll notice that each of its dots, or pixels, contains a trio of vertical stripes or “subpixels” colored red, green, and blue, with narrow black areas between them. This arrangement dates from the dawn of color television but has persisted into the age of advanced liquid-crystal-display computer monitors. A Cupertino, CA, startup called ClairVoyante thinks it’s time to mix things up – and believes the result will be brighter, cheaper displays. Red, green, and blue together make white, but to make a screen’s whites even whiter, ClairVoyante’s designers are adding a white subpixel to the mix (top). At the same time, they’re making each subpixel wider, so that a pair of subpixels will take up the same space as three conventional subpixels (bottom). That means there’s less black space overall; the combination of white subpixels and the new geometry almost doubles a screen’s brightness. It also cuts manufacturing costs, since the design requires only two-thirds as many “source drivers,” the electronic devices at the top edge of a screen that control each column of subpixels. ClairVoyante expects Asian manufacturers such as Samsung to launch the first “RGBW” devices – probably small-screen gadgets such as cell phones – in 2006.

Rear View Backbeat
Time may be running out for the bulky bass speakers on cars’ rear window ledges now that the window itself can produce the same sounds. “We were researching active noise control when we discovered the window glass is an excellent membrane for generating low frequencies,” says Urban Emborg, president of Sweden’s A2 Acoustics. In fact, says Emborg, preliminary tests show that at very low frequencies glass could produce less distortion than premium subwoofers. In addition to boosting sound quality and freeing up trunk space, says Emborg, A2’s glass-speaker system could ease vehicle assembly, since the glass and electronics can be preassembled as one unit. The system sends signals from a car’s audio amplifier to tubes 10 millimeters in diameter that lie along the bottom of the window frame. The tubes are made of a “piezoelectric” material that expands or contracts when a voltage is applied to it; the tubes create vibrations that propagate into the glass, producing deep notes that are audible in the vehicle but not outside. A2 is developing methods for mass-producing the technology.

Speed Reader
Ever wished you could speed-read? A new program called Jump could save you the bother. The software scans large documents and groups details about people, places, and other topics under descriptive headings, creating easy-to-navigate maps of the documents’ content. And it’s phenomenally fast, able to read more than 600 pages in 10 minutes. The idea is to let users get the gist of documents quickly and then find any specific information they want, says Nick Jakobi, head of linguistics research for Corpora, the Guildford, England, company that created the program. Unlike the “find” command in a word-processing program, Jump doesn’t just search for strings of characters. It uses natural-language-processing techniques to break text into noun phrases and verb phrases and identify the subjects and objects of verbs. It can thus find not just mentions of a person’s name, say, but other references to that person, even those that use job titles or pronouns. Corpora launched the program this spring as a tool for lawyers, journalists, and others in text-heavy professions.


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