Technology Bulletin 1355

DN Staff

November 2, 1998

8 Min Read
Technology Bulletin

Land-mine detector feeds on feedback technology...

A Penn State-led team has developed a prototype land-mine detector that promises to be safer, more accurate, and easier to operate than existing models. Jeffrey L. Schiano, assistant professor of electrical engineering at Penn State, and Mark D. Ginsberg, principal investigator at the U.S. Army's Construction Engineering Research Laboratory, designed the detector. The instrument is said to be the first such device to apply feedback technology and quadrupole resonance (NQR) spectroscopy, an analytical tool developed in the late 1940s for crystal structure studies. Schiano reports that in the 1960s and 1970s, researchers in the U.S. and Russia independently developed experimental NQR-based detectors for use in mine fields. More recently commercial NQR-based systems have surfaced in the U.S. and Britain for narcotics and explosives detection in airline baggage. However, all of these instruments are hampered by the fact that the NQR signal generated by explosives is small, easily drowned out by background noise, and has a short duration. The researchers have overcome these problems by applying feedback control concepts to enhance the signal and separate it from background noise. The new device's feedback-control algorithms automatically increase or decrease the repetition rate of the radio frequency pulse and quicken or slow the time that elapses between the creation and collapse of the disturbance in the nuclear magnetization. E-mail [email protected].

...while portable soil gauge spawned from mine detector

Several states now have under test a portable gauge that measures the stiffness, or bearing strength, of soil--a key variable in road building. Humboldt Manufacturing Co. (Norridge, IL) makes the device, thanks partly to funding provided by the Federal Highway Administration designed to find new uses for military technology. In this case, the Soil Stiffness Gage (SSG) technology borrows on that proven in the detection of non-metallic land mines for the Army. The 25-lb, battery-powered gauge creates vibrations that are used to measure soil properties. Its supporters say the unit is lighter, faster, safer, less labor-intensive, and more accurate than current methods. With the older measurement devices, construction sites are often under sampled, causing inadequate compaction to go undetected, or feedback provided too late for cost-effective correction of problems. The SSG's foot bears directly on the soil and supports the weight of the device via several rubber isolators. Also attached to the foot are the shaker that drives it and sensors that measure the force and displacement-time history of the foot. Low-cost computer chips make the instrument feasible, according to Charles Nelson, vice president of engineering at Consulting Engineers (Minneapolis), a principal in the project. E-mail [email protected].

Low-cost chip sniffs out harmful chemicals

Also in the detection arena, researchers at the Oak Ridge National Laboratory (ORNL) are just a nose away from producing microsensors that can detect mercury, natural gas, carbon monoxide, and other chemicals. The "nose on a chip," which could be incorporated into household gas appliances, consists of an array of tiny sensors on one integrated circuit and electronics on another. By selectively coating the microcantilever arrays with appropriate chemicals, the chip can be customized to detect virtually any chemical or biological species. The tiny, diving-board-like platforms bend ever so slightly in the presence of chemicals. As a result, selective coatings make them sensitive to different gases or chemicals. For example, a gold-coated microcantilever could detect mercury. "Most existing sensors can detect only single species and have large volume and power requirements," says Chuck Britton one of the ORNL developers. "Our solution is to use miniature arrays of low-power sensors and electronics on a single chip to simultaneously detect many different species." E-mail [email protected].

Air curtains contain toxic fumes in underground passageways

How can users be safely evacuated if a fire breaks out in an underground train corridor or in a road tunnel? Simply create an air curtain. The air curtain system, developed by France's Centre Scientifique et Technique du Batiment (CSTB), uses air from the polluted area to push back the polluted front so that fresh air can flow in. The system consists of an air intake, fans, and an air nozzle. To prevent smoke from entering, the air curtain must be correctly positioned and the speed of the air jet calculated according to the difference in pressure and the corridor's height. CSTB researchers studied the behavioral laws for these parameters on models and on a full scale in their Jules Verne climatic wind tunnel as part of Paris subway and French railway and highway projects. The advantage of the air curtain, the study reports, lies in its capacity to create a virtual barrier between the inside and outside of the endangered passageway. In other words, the air curtain is placed in a section of limited height separating the two adjacent areas. It must blow obliquely against the air flow to be counteracted. Air is blown across the entire width of the corridor, creating rollers pushing against the ground. Air tightness of this "dynamic door" depends on the speed of the air jet, which, in turn, depends on the difference in pressure and its consistency over the corridor's entire width. FAX +(33) 2 40 37 20 60.

Research delves into energy system suspended by wires

In the basement of a Cornell University engineering building, a large aluminum cylinder envelops microexplosions that one day could contribute to developing more efficient electricity generation. That technology, nuclear fusion, may now be a step closer. The so-called inertial confinement fusion research program recently received two infusions of funds totaling more than $500,000 from the Department of Energy. Cornell's program, presided over by plasma physicist David Hammer, has received support over the past four years from a small contract entered into with Sandia National Laboratories. The Sandia/Cornell fusion system uses x-rays instead of a laser beam. Called simply Z, the system is far less costly than a comparable laser facility, according to Hammer, perhaps only 20% of the cost. The Z machine, measuring 90 ft in diameter, generates an extremely high power x-ray pulse to create temperatures in the millions of degrees in the hydrogen fusion fuel. The direct generation of such x-rays could significantly increase energy efficiency when compared with the huge power demands of a laser device. The Z machine accumulates energy over a period of two minutes, then, in a burst of current lasting a tenth of a microsecond, bombards its target, made up of 240 or more wisp-thin wires of tungsten or other metal strung together in a circular array. The wires explode, creating a hot ionized gas. The intense magnetic field created by the current "pinches" the plasma, generating x-rays. In a fusion reactor, this powerful source could be directed at the hydrogen fuel. E-mail [email protected].

Company to focus on fuel cells for transportation applications

United Technologies Corp. (UTC, South Windsor, CT) has formed a limited-liability company, International Fuel Cells, LLC (IFC), to expand its fuel-cell business in the transportation market. Both UTC and Toshiba have committed funding for the capital and development activities needed to adapt the fuel-cell technology for transportation operations. Meanwhile, ONSI Corp., an independent subsidiary located at the UTC site, will continue its worldwide activities in the stationary fuel-cell power plant market. ONSI's fleet of 160 fuel-cell power plants, each providing 200 kW of power, recently surpassed two million hours of accumulated operation. Existing facilities at the IFC site will be modified to expand the company's Proton Exchange Membrane (PEM) fuel-cell technology development and perform pilot manufacturing of PEM products for cars and buses. A fuel-processing test facility also is under construction to test gasoline and alternative fuels. "Our new organizational structure will allow IFC to better focus on the transportation fuel-cell market, while ONSI continues its industry-leading role as a supplier of commercial fuel-cell power plants," explains IFC President Robert Suttmiller. Phone Peg Hashem at (860) 654-3469.

Institute additions address future vehicle designs and tests

Southwest Research Institute (SwRI, San Antonio, TX) recently completed a $2.2 million expansion of its vehicle systems research facility. Among the upgraded capabilities: transmission, filtration and contamination, hydraulics, and conventional and hybrid vehicle design, development, and testing. Several test stands have been developed and integrated into a new fuel system contamination research lab as part of the expansion. Six high-horsepower, electric dynamometer test stands can handle the increased transmission activity needed to develop future vehicle drivetrains, reports Gary Stecklein, director of the Department of Vehicle Systems Research. "We have just completed our first fuel-cell test stand development and evaluation," Stecklein adds, "and are undertaking R&D to improve fuel-cell performance through pulsatile operation." The expanded facility also increases SwRI's conventional, electric, and hybrid vehicle development, including the ability to test hybrid vehicle components, such as drive motors and batteries. FAX Joe Fohn at (210) 522-3547.

Customized prototype sensors available 'on call'

Spectrol Electronics reports it can provide prototypes of a fully customized, modular sensor with analog and digital multi-function outputs in two weeks. The price: $1,000, with no tooling charge. The quick turnaround contrasts to typical high-end, multi-output custom sensor prototyping that normally requires significant design and tooling costs. This can run to several hundred thousand dollars and require lead times up to two years, according to Brad Canfield, Spectrol Electronics' manager of OEM products. Among the benefits listed for the new DigiSenseTM sensors: removal of external limits switches, microswitches, wire harnessing, and lower labor costs. FAX (909) 923-6765.

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