ASEE Prism Magazine
briefings  

Which End is Up?

We've all seen pictures of astronauts pirouetting weightlessly in space, floating freely about, no longer tethered to the ground by gravity's pull. And while it all looks like effortless fun, it seems that prolonged exposure to weightlessness is no lightweight matter.

We need gravity to give us the vertical cues to orient ourselves to our environment. In short, it helps us keep our balance. And going without gravity for long durations leaves us seriously disoriented. Astronauts who spend lengthy periods in space often suffer myriad problems, like "downs illusion"—a sensation that occurs when they're upside down and begin to sense that whatever is beneath their feet is a floor, even though intellectually they know better.

Weightlessness induces nausea and sickness in two-thirds of astronauts. And those who venture on space walks are also prone to sudden attacks of high vertigo, leaving them with a terrifying feeling of plummeting into space. Moreover, the aftereffects— sometimes in the form of disorienting flashbacks—can last for days, weeks, even months. "The longer you fly in space, the more time you need to recover full balance function," explains Charles Oman, director of the Massachusetts Institute of Technology's Manned-Vehicle Laboratory.
To help better understand and remedy the problems caused by a lack of gravity, NASA's Johnson Space Center recently awarded $3.6 million to MIT's Center for Space Research to develop experiments for a virtual-reality system that will be installed in the International Space Station now being assembled in orbit. Oman is the project's chief investigator.

It's hoped that within two years the device will be used to help conduct a series of 10 motion-related experiments, some as simple as having people trying to catch tossed balls. The tests will be conducted before, during and after long flights. Why use a virtual-reality system to simulate weightlessness on people who are in a gravity-free space station? "To have a controlled visual environment," Oman explains. For instance, the system should let researchers measure the precise point at which astronauts begin to feel the onset of "downs illusion."
Eventually, virtual-reality machines may be used to help train astronauts in advance of long flights to cope with the debilitating effects of weightlessness. It's also anticipated that the results will increase understanding of human balance disorders on earth and lead to new rehabilitative therapies.
And those are potentially some heavy-duty benefits.

Weaponry for the Plagiarism Police

AUSTRALIA—Mad as hell because someone tried to pass off your work as his or hers? A researcher at one of Down-Under's leading universities is fine-tuning a way to beat this annoying problem.

Krisztian Monostori, a Ph.D. student at Monash University's School of Computer Science and Software Engineering in Melbourne, has developed an advanced algorithm to detect plagiarism. He hopes it will make would-be copycats think twice before lifting other people's work and using it without permission. "Because technology has made access to information so readily available, there's a growing need to have better ways of policing how original texts are used," Monostori says.

Monostori's work uses what's known as a suffix tree to search vast numbers of documents much more quickly and accurately than other available methods. "'Suffix trees' have been used in many other areas, such as file compression and DNA matching in molecular biology," Monostori says. "But algorithms so far haven't used suffix trees for plagiarism detection. My method uses a two-stage approach, with suffix trees used in the second stage to find the exact positions and lengths of matching text."

Using his algorithm to build a structure for a particular document, Monostori can then compare it to others for overlapping content. While he says the most obvious application will be to detect plagiarism in student presentations and in research papers, Monostori believes it will also be valuable for identifying documents placed on the Internet without authorization. "The package I've developed will help search for and identify such cases of copyright infringement," he says, adding that the research will also be useful in developing more advanced search engines.

The university says that if an evaluation of the research confirms its merit, a software product could be commercially available in about two years.

Researchers Go Batty at Caltech

Look! Up in the sky! It's a bird, it's a plane, it's, it's . . . it's a Microbat? Yep. Palm-sized, weighing in at no more than 11 grams—about the same as two nickels—and with rapidly flapping wings, the Microbat is a MEMS, or a microelectromechanical system.

The mini-aircraft, developed at the California Institute of Technology's Micromachining Laboratory, can be fitted with a tiny video camera to let the operator—who controls the craft with a joystick—see what it "sees." There are now three Microbats, each taking six months to produce since the project began a little more than 18 months ago.

"This technology is mainly for research. Flapping-wing aerodynamics is at its very, very early stages," explains Yu-Chong Tai, a professor of electrical engineering at Caltech. Tai and his team were put to work on the Microbat by the Department of Defense, which is looking to develop small, fast, highly maneuverable, unmanned, and mostly silent reconnaissance aircraft.

Flapping-wing aircraft have many advantages over the fixed-wing variety—at least at the mini-level. They can turn and swoop more quickly, they can hover like hummingbirds, and they're quieter. But Tai sees no need to ever transfer the technology to full-sized jets. "Today's fixed-wing passenger aircraft are really, really efficient," he says, and perfectly suited for open-space flight.

The Microbat is constructed mainly of titanium, was fairly cheap to develop, and could be inexpensive to make. That's because most of the technology it uses is off-the-shelf. So far, Tai says, the DOD has spent only $1.3 million on the project. In U.S. defense spending terms, that's bird feed.

Illustration by Lung-I LoBut while the technology for the electronics and framework of the Microbat is already available, as Tai has proven, the MEMS' power source remains feeble. The current generation can fly for only 50 seconds, at speeds nearing 50 mph. Once it loses power, the Microbat floats to a soft landing, its wings still flickering a bit, "like a wounded bird," Tai says. And therein lies the rub. He estimates it may be another decade before more efficient lightweight batteries are built, even though the Pentagon is spending millions upon millions of tax dollars on battery development.

Beyond military applications, Tai thinks the Microbat could prove useful as a rescue tool, helping to find victims inside damaged or smoke-filled buildings, or people lost in thick woods. But until someone invents a better battery, this bat won't be making trips that go far from its home cave anytime soon.

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