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WWatt’s TechnologyYou can compareApples withanything you likeApple’s Mac computers have been highly rated in arecent consumer report that compares a variety ofdifferent computer system. The MacBook receivedtop honours in the 13-inch category as well as the14-16 inch category and the 17-inch category. The 15 inchMacBook Pro established the highest score with 75 out of 100while the Toshiba Satellite came in second with a score of 64.But it was not all in Apple’s favour as its MacMini fell behindHP’s Pavilion Slimline. The best all-in-one computer was Dell’sXPS rather than the iMac, which many people thought wouldeasily win this category.In terms of technical support services, Apple took top honoursfor the desktop and notebook categories. The company achievedan 80 percent solve rate for phone-in services, compared with anindustry average of just 60 percent.Apple’s iPhone has show similar results, recently receivingthe highest score ever on the JD Power consumer-satisfactionstudy. The handset received a score of 791 out of 1 000, leadingamong the smartphone and basic cellphone categories. LG andSamsung scored more than 751 in the smartphone categorywhile BlackBerry disappointingly achieved a score of 739 interms of consumer satisfaction.Concrete thatheals itself – muchlike human skinResearch engineers working at the University of Michiganin Ann Arbor have developed a new concrete that can“heal” itself. The new concrete composite can evenbe bent into a U-shape without breaking and, whenstrained, it forms hairline cracks that automatically seal after afew days of light rain.The flexible concrete is just as strong as it was before it developedthe hairline cracks.Experiments done by Professor of Engineering, Victor Li, and hiscolleagues show that the self-healing specimens recovered most, ifnot all, of their original strength after being subjected to a threepercent tensile strain – in other words the specimens were stretchedto three percent beyond their initial size.It’s the equivalent of taking a 30 metre structure and stretchingit by almost a metre, enough of a strain to severely deform steelor catastrophically fracture traditional concrete. When it hashealed itself, the concrete was found to have the same stiffnessand strength.The engineers did find that cracks in the concrete must be keptto below 150 micrometres and preferably below 50 micrometres toallow full healing. Li and his team have been working on makingbendable concrete composites for the past 15 years.Known as ECC the bendable concrete is studded with speciallycoated reinforcing fibres that hold it together. ECC remains intactand safe to use at tensile strengths of up to five percent. Thiscompares with traditional concrete that fractures and cannot carrya load at .01 percent tensile strain.According to Li the new concrete could make structures safer.Self-healing concrete worksbecause it can bend. When it’sstrained, many microcracksform instead of one largecrack that causes it to fail.Here, a specimen is bendingas a force of five percenttensile strain is being applied.Regular concrete would failat .01 percent tensile strain.Image: Nicole Casal Moore/University of Michigan36
Think about whereyou’re going – andthen just go thereSpanish scientists have made a wheelchair that can becontrolled by thought waves and this new gadget willallow people with disabilities to think about wherethey want to go and then get there. The wheelchairuses a laser scanner to create a three-dimensional picture of thearea around it, which is displayed in front of the user.By concentrating on a particular part of the display, thewheelchair responds and follows the directions. A skullcap,fitted with electrodes, is used to detect the brain activity andwork out the desired destination.The wheelchair was developed by Dr Javier Minguez of theUniversity of Zaragoza in Spain. Volunteers who have tested thechair were able to master its control with 45 minutes. Accordingto Minguez, tests have been conducted on volunteers and all thesubjects apparently solved the navigation tasks they were given.The wheelchair is the latest device to be controlled bybrainwaves but it is still a long way from commercial developmentbecause it can handle just two thoughts a minute. However, DrMinguez is confident that, in time, a more sophisticated versionwill be developed that will respond more rapidly to the user’sthought.In 2007, Ambient demonstrated a motorised wheelchairthat was controlled by sub-vocal speech. The user thinks of aparticular word and a sensor collar around the neck detectsthe electrical signals sent from the brain to the larynx andcompares the signal patterns with pre-programmed words thatcontrol the wheelchair.A similar sub-vocal speech technology has been demonstratedby the National Aeronautics and Space Administration forspacesuit communication devices. In another use of thetechnology, the collar can be connected to a speech synthesiserallowing the wearing to actually speak.WWatt’s TechnologyThrow yourcoffee cup inyour diesel tankBung a disposable polystyrene coffee cup into yourtank-full of diesel and you can immediately boost yourpower output by about five percent. The disposablecoffee cups work even more effectively in biodiesel asit dissolves almost instantly when submersed in the fuel.Song-Charng Kong, a mechanical engineer at the Iowa StateUniversity in Ames, says the experiment was conducted to finda way to dispose of trash and generate power under battlefieldconditions. The study was funded by the United States DefenceDepartment.Kong and his colleagues dissolved polystyrene into biodieselat concentrations of between two and 20 percent by weight andfound that the increase in power output remained constant.Tests with a mixed fuel used in a tractor engine to generateelectricity, showed that as polystyrene concentrations increased,so the power output increased until the fuel became so viscousthat it could no longer combust.Kong believes the reason for the increase in power is thatwhen polystyrene is added, the fuel gets thicker, creating greaterpressure inside the combustion chamber, causing earlier ignitionof the fuel and boosting output. When it reaches a concentrationof about 15 percent it is so thick that the fuel pump overheatsPolystyrene is traditionally a difficult material to recyclebecause it is extremely light and is also very bulky, making ituneconomical to ship to recycling plants.Dissolving the polystyrene in biodiesel doesn’t eliminate theharmful emissions though. The researchers found that by addingpolystyrene, emissions of carbon monoxide, soot and nitrousoxides were higher because they did not burn completely duringcombustion.However, Kong and his team are confident that they willimprove the injection systems to achieve a more complete burnand in that way reduce emissions to acceptable levels.June 2009 37
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