Technology bulletin 1025

Bees take sting out of landmines

While most bees will live normal lives this summer just hunting for pollen, a select few will be equipped with tiny radio frequency (RF) tags and sent out to hunt explosives. The University of Montana (Missoula, MT) and university entomologist Jerry Bromenshenk are coordinating this sting operation in the hopes that bees can locate landmines or unexploded ammunition on firing ranges or old battlefields. Engineers at the Pacific Northwest National Laboratory (Richland, WI) modified commercially available radio-frequency tags to track the movement of bees. For the man-made beehive, they designed special electronics and software for RF devices that "read" information on the tags. As a bee leaves the hive for the day, the reader scans the tag on each bee and sends the individual identification code, direction of flight, and the time of day to a modem. The modem downloads the data to a central computer. The process is repeated when the bee returns. A system of analysis tools will be installed inside the hives to scan the pollen for chemicals found in explosives. Researchers will use the tracking and analysis data to help pinpoint landmine locations. Researchers from Sandia National Laboratories, Oak Ridge National Laboratory, and the Environmental Protection Agency are developing the necessary analysis tools. E-mail: [email protected].

Car sees with single-chip vision

A toy car avoids obstacles along the test track without help from a human controller. Instead, it relies on a single-chip robotic vision system developed by Ralph Etienne-Cummings, an assistant professor of electrical and computer engineering at John Hopkins University (Baltimore, MD). The system rolls several functions into one microchip. The device performs analog and digital processing, extracts relevant information, makes decisions, and communicates them to the robot. Because decisions are made within the microchip, rather than relying on a separate computer, the response time is faster than other robotic vision systems, Etienne-Cummings says. He mounted two light sensors as "eyes" on the front of the vehicle. The microchips force the car to follow a line detected by the sensors, unless an obstacle appears in its path. If the chips decide that it is more important to avoid the crash rather than follow the line, they steer the car away from the obstacle. The system also "remembers" how it turned, so that it can steer the car back to the line to resume its original course. The sensors process and react to light as soon as it hits the system. Etienne-Cummings hopes eventually to use this computational sensor technology to enable a robot arm to keep pace with a beating heart. If this technology is perfected, surgeons may use the robot to clear a blocked cardiac artery without having to stop the heart first, as doctors must do today. To achieve such advances, closer collaboration between microchip designers and the mechanical engineers that build robots is essential, Etienne-Cummings says. "The people who assemble robots don't have access to the sensors that I design," he says. "I think that's one of the things that have prevented computational sensors from making greater inroads in robotics. We are two divided communities, and we haven't been talking to each other. Now, we're finally starting to have those conversations." E-mail: [email protected].

Holographic radar keeps fighter planes stealthy

Keeping fighter pilots safe is a major concern as U.S. troops continue to fly over Kosovo, especially if a stealth fighter is detected by radar. To help ensure a plane's "stealthiness," researchers at the Department of Energy's Pacific Northwest National Laboratory (Richland, WA) developed a Holographic 3-Dimensional Radar Camera. The camera records images of pre- and post-repair inspections to ensure radar-absorbing material performs as expected, particularly in cases where the aircraft has been damaged, even slightly, during flight. "By using the 3D radar camera, ground crews can better determine if critical portions of an aircraft are in a "go" or "no go" condition." An operator holds the camera about 2 feet from the area to be inspected and "shoots" the aircraft with low-power electromagnetic waves. An antenna array receives the reflected energy and sends it to a computer for processing. Software algorithms translate the level of reflection into a radar image, that then is projected into head-mounted virtual-vision glasses. Each snapshot covers a 1 ft² area. Through the glasses, the operator sees an image depicting the brightness of the aircraft's radar reflection, or signature. The image displays the radar signature in green, yellow, or red to denote pass, assess, or fail, respectively. E-mail: [email protected].

Computers enter materials science. Result: better composites

Materials scientists don't have a crystal ball to help them predict the mechanical properties of a composite when they alter its fiber and matrix properties. James Browne, at the University of Texas, and Greg Rodin, of the Texas Institute for Computational and Applied Mathematics (TICAM), hope to integrate these experiments with computers. By taking a computed tomography (CT) scan of the material, researchers can determine its internal density at the 10-micron scale and see the fibers imbedded in the matrix. The scan produces x-ray slices of the material as a series of image files. Then, Browne and Rodin create a 3D model of the material from these 2D slices. They convert the CT data to a representation in a Scalable Distributed Dynamic Array (SDDA). SDDA generalizes the standard array concept into a structure that adapts at runtime to the size and shape of the object it is representing, after which it is automatically distributed across the processors of a parallel machine. The simulations look at how composites deform and ultimately break under strain. These results should make it possible to save time and money by helping to design a material with desired features more quickly than the traditional trial-and-error methods.

Researchers create self-assembling nanospheres

Self-assembling nanospheres that fit inside each other like Russian dolls have medical, industrial, and military potential. The durable silica spheres, developed at the Department of Energy's (DOE) Sandia National Laboratories (Albuquerque, NM), range in size from 2 to 50 nm and form in seconds. Because of their size and uniform pore structure, they could be used for the controlled release of drugs in the body. The porous particles also have characteristics superior to fillers used in encapsulants for weapons and tools, say Sandia researchers. Nanosphere fillers would occupy the same volume, but because they are porous, they can expand and contract with much less stress. Some pore shapes trap materials, while others allow free flow in and out of the spheres. The nanospheres--essentially a 3D creation rather, than a film or layering of films--were created by drying liquid droplets blowing through a furnace, not by evaporating a liquid layer deposited on a substrate. The mixture begins with a homogeneous solution of soluble silica plus surfactant prepared in an ethanol water solvent. In a continuous process that takes about 6 sec/particle, the aerosol particles are dried, heated, and collected. Researchers start out with liquid droplets that pass through a reactor. As liquid evaporates, the rest of the material self-assembles into a completely ordered particle that, when heated, maintains its shape. E-mail [email protected].

A close look at atomic behavior

Kevin Hemker, an associate professor of mechanical engineering in the G.W.C. Whiting School of Engineering, wants to build a better jet engine. He's beginning at the atomic level...discovering how atoms arrange themselves in metal alloys through a $1.3 million high-resolution transmission electron microscope recently installed at Johns Hopkins' Homewood campus. The new microscope uses a field emission gun to send a powerful beam of electrons through a thin foil. This foil has been ground and polished to a height of less than 100 atoms. The electron beam travels through it, producing pictures of the atomic structure that can be viewed on a phosphorescent screen, captured on film or videotape, or preserved as digital information. "The U.S. Air Force and others in the aviation industry want to be able to predict in a computer how well new metal alloys behave, without having to physically cast these alloys and test them," says Hemker. By knowing how these atoms arrange themselves can help researchers predict how well these materials will withstand the high temperatures, centrifugal forces, and corrosive gases that exist inside a jet engine. Fax: (410) 516-5251.

Bar keeps children safe

Whether or not to equip school buses with seatbelts has long been debated with little consensus. Two mechanical engineering undergraduates at The Johns Hopkins University (Baltimore, MD) developed an alternative--a restraining bar system. Patterned after roller coaster safety equipment, the heavily foam padded bar would be bolted to the school bus floor. After the children are seated, the bar pivots down to a locking position in their laps. A simple manual-release lever allows children to leave their seats quickly at a bus stop or during an emergency. Its inventors, 22-year-old seniors Stephen Pantano, of Cranston, RI, and William Thompson, of Newtown, PA, successfully tested the device with a crash-test dummy and two school bus seats. Pantano says, "We covered the bar with three layers of foam padding, which helped spread out the force of the crash." This school bus safety system was one of 12 projects completed this year by undergraduate teams in the university's Whiting School of Engineering's Design Project. FAX: (410) 516-5251.

Quicker PCs with parallel arrays

Computers soon may get a boost in their processing powers from Cornell University's (Ithaca, NY) computer scientist Carla Gomes. Traditionally, computers solve problems through trial and error. They perform combinatorial types of problems by setting values for a number of variables that must meet certain constraints. Gomes says combinatorial problems lend themselves to parallel processing so that several random starting points can be tested at the same time, with the whole process ending as soon as one of the processors finds a solution. Gomes plans to experiment with an array of linked desktop computers. The system will consist of 32 top-of-the-line PCs connected via an ultra-high-speed network. For the kinds of problems Gomes is considering, such a configuration can match the performance of a supercomputer at only a fraction of the cost. Gomes expects computers may someday help arrange machines in a factory, schedule the distribution of materials, solve problems in biology, design cellular phone networks or layout of microcircuits. E-mail: [email protected].