Tuesday, July 27, 2004

"VR: Software uses sculptor's touch on virtual objects"
Virtual reality software has long held the promise of enabling designers to sculpt the sleek curves and contours of a new product from "virtual clay," but until recently designers had to learn a whole new procedure for working with computer-aided design (CAD). Until now, virtual shapes could only be sculpted via keyboard and mouse input to define "splines" or similar mathematical objects that determine a curve's shape, but have nothing to do with sculpting. More recently, haptic feedback devices have arrived that offer a more direct relationship between the hand and a virtual object, but they still lack the naturalness of hand-shaped clay. A project of the State University of New York at Buffalo is seeking a direct intuitive method for working with virtual shapes in a CAD system using the type of glove developed in virtual reality systems. Using the approach, it is possible to work with actual clay to sculpt a shape, which is then automatically transferred to a CAD representation. "Ours is the only technology capable of transferring touch directly from the user's hand to the virtual object," said associate professor Thenkurussi Kesavadas, director of the Virtual Reality Lab
Audio Interview / Text:

Friday, July 23, 2004

"LED: Reflector lets LEDs replace light bulbs"
Light bulbs create more heat than light. But a professor at Rensselaer Polytechnic Institute (Troy, N.Y.) has invented a 99 percent efficient, omnidirectional reflector that he claims will allow light-emitting diodes to replace conventional light bulbs within five years, saving energy and related cost. Fred Schubert, Wellfleet senior constellation professor of the Future Chips Constellation at Rensselaer, has demonstrated his LEDs in red and blue but is pursuing white LEDs for light bulb replacement. "In an LED, light emits from inside the semiconductor in every direction, but our mirror reflects light equally well no matter what the angle of incidence. Other types of reflectors are only efficient when the angle is normal [90� perpendicular to the surface]," Schubert said.
"QUANTUM: Cure in sight for 'pink noise' in quantum dots"
The troublesome flickering that plagues quantum-dot development today may be closer to a cure, thanks to a team of researchers at the University of Chicago. By analyzing the power spectrum of quantum-dot blinks, the group found that, unlike semiconductors, individual quantum dots exhibit exactly the same qualities as their aggregations, thereby simplifying the measuring apparatus needed to fix the problem. "This blinking phenomenon happens everywhere in nature at the nanoscale," said Matthew Pelton, a research associate at the university's James Franck Institute. In MOSFETs, for example, "current blinks when electrons get stuck in these nanoscale traps," each of which holds the electrons for a particular time. "One trap might hold electrons for a short amount of time and another holds them for a long time," Pelton said, but together they exhibit so-called 1/f noise, or "pink noise." If quantum dots behaved like MOSFETs, which until now was the common wisdom, then curing a flickering problem would mean studying the individual quantum dots, since each would have a characteristic blinking frequency. However, Pelton and his colleagues Philippe Guyot-Sionnest and David Grier (who has since moved to New York University) found that each quantum dot exhibited the same pink-noise profile all by itself. Thus, when quantum dots are observed at the macroscale, the same phenomenon is seen as when the output of a single quantum dot is observed.

Friday, July 16, 2004

"EDUCATION: Engineering schools abrim with talent"
The coursework is no picnic, and once you finish, the job market can be iffy. And yet, more U.S. students are enrolled in engineering graduate schools than ever before, according to a new report from the National Science Foundation. They numbered almost half a million in 2002, NSF says, a figure that surpasses by 5 percent the previous peak, achieved in 1993.
"To some extent the all-time high in graduate enrollment in science and engineering is following trends in the total U.S. college-age population," said Jean Johnson, an NSF senior analyst. But demographics alone can't account for the entire uptick, Johnson said, especially in fields like electrical and biomedical engineering, which jumped 10.7 percent and 20.3 percent respectively. Here, according to Johnson, engineering specialties on the rise reflect the students' practical eye for interesting employment opportunities. "Much of the increase in specific fields of science and engineering can be attributable to students going where they perceive the jobs to be," said Johnson. That's certainly the case for a trio of would-be engineers who have already begun to make a mark in the profession � Dat Truong and Landon Unninayar of Johns Hopkins and Alia Sabur from Drexel University.

Wednesday, July 14, 2004

"CHIPS: Electron spin detector may yield denser chips"
Spin-dependent transistors could one day harness electron spin to encode up to 10 states (as opposed to binary logic's mere two) in single-electron devices-enabling chips with a million times the density of today's memories, according to the University of Arkansas. A precise understanding of how an electron's spin rotates as it moves through a material could enable such single-electron, spin-dependent devices. Unfortunately, there has been no instrument available to measure electron spin, so even the first step toward a spin-dependent computer has not been taken-that is, to carefully characterize the properties of a spin-dependent transistor, according to Paul Thibado, associate professor of physics at the University of Arkansas.

Friday, July 09, 2004

"ROBOT: copies cats to eliminate spin in free fall"
The National Aeronautics and Space Administration's "weightless wonder" aircraft will be the testbed this week for a robot that exhibits catlike motion in free fall. The work could one day lead to designs that eliminate the need for retrorockets, gas jets and gyroscopes in satellites and other spacecraft. The robot rotates without angular momentum by changing the length of parts of its body while rotating them in opposite directions, much as a falling cat does. Managing that momentum is the bane of space navigation today, complicating almost every space-based maneuver, introducing unwanted spin that must be compensated for with retrorockets or gas jets. In devising the concept, project leader Gregory Ojakangas, a physics professor at Drury University (Springfield, Miss.), borrowed from a species that flouts the rules of angular momentum. "When you drop a cat upside down, it always lands on its feet, with no spin. It doesn't paddle the air � that would impart spin � it just expands its upper body and rotates it, then contracts its upper body and rotates in the opposite direction," said Ojakangas. "In that sense, ours is not a new idea; nature has been doing it for I don't know how many millions of years."

Monday, July 05, 2004

"MAGNETISM: Jumbo magnet in Florida exerts worldwide pull"
An enormous magnet, boasting a rock-steady field and a bore twice the size found elsewhere, is expected to draw the global scientific community to its Florida home. Opened last month in Tallahassee, the magnetic system offers a 105-millimeter bore and a record birth "weight," or magnetic field. Standing 16 feet tall and weighing more than 15 tons, the National High Magnetic Field Laboratory magnet is expected to live at least 10 years, and could survive for decades. On its inception date, July 21, the magnet produced a uniform field of 21.1 Tesla, which is expected to hold steady for years, a product of the resistanceless state of the superconducting electrons orbiting its bore. The magnet is now being readied for an international user community and, thanks to its superconducting coils, it will stay running for years to clean up a backlog of experiments waiting for such a device.

Friday, July 02, 2004

"QUANTUM: wells shed light on lightbulb alternative"
A promise of future lightbulb replacements that are almost 100 percent efficient came to light in a recent proof-of-concept experiment carried out by the National Nuclear Security Administration's Los Alamos National Laboratory and Sandia National Laboratories. In demonstrating these "light engines," experimental quantum wells emitted ultraviolet energy so rapidly that before that energy could become radiation, it was absorbed by integrated nanocrystals that glowed like a fluorescent tube. Now, "the process is 55 percent efficient," reported Sandia researcher Daniel Koleske, "because, unlike the fluorescent bulb, which must radiate its ultraviolet energy to the phosphor in the form of photons, the quantum well here delivers its ultraviolet energy to the nanocrystal very rapidly, before photons even form." As a consequence of the conversion process from UV photons to visible photons, normal fluorescent lightbulbs are less than 10 percent efficient. But in the future, light engines currently under development by companies working with the national laboratories could increase that efficiency to almost 100 percent.