A portable ground-penetrating radar detector for buried land mines is being developed for the U.S. Defense Department by Battelle and Ohio State

The device resembles a small satellite dish--30 inches across--that is strapped to the front of the operator, who uses it to scan the area ahead. To detect small, nonmetallic mines that scatter very little energy back to the sender, sophisticated antenna systems must be developed that respond to the tiny return signals without creating interference of their own. In addition, the radar must isolate the particular characteristics of these mines so they can be discriminated from harmless objects buried in the ground.

Battelle and Ohio State are also teaming to develop an airborne radar system that uses a helicopter to locate unexploded bombs buried at former U.S. military installations.

Insects devour about $500 million of stored grain in the United States annually, according to an Oklahoma State University estimate. To counteract that, methyl bromide and phosphine are used to control insect infestation of stored grain. By 2001, however, methyl bromide will be banned by the federal government to protect the stratospheric ozone layer. Scientists want to limit the use of phosphine in light of reports that some insects are building an immunity to the chemical.

Researchers from Purdue University in West Lafayette, Ind., adapted the chilled-aeration technology, which has been used for some time in Europe to control the temperature and moisture of stored grain, thereby inhibiting insect populations. The Purdue system consists of a mobile chilling unit built by AAG Manufacturing in Milwaukee. This unit contains a vapor-compressor refrigeration system whose air ducts are connected to the fan units on grain bins. The blower is equipped with variable-frequency-speed drives to reduce energy consumption by as much as 20 percent, according to Dirk Maier, assistant professor of agricultural engineering at Purdue.

The chiller reduces temperatures down to less than 60 degrees F. Wheat chilling trials conducted at Kokomo Grain Co. in Amboy, Ind., and Mennel Milling Co. in Mexico, Ind., demonstrated the chiller was capable of cooling grains to a protective level in an average of 220 hours and would keep the grain cool for four to six weeks.

The chilled-aeration technology is mature enough to be used commercially, noted Maier. "We are working on the economics to reduce the costs a bit. Mass production of the chilling units would help."

Fifty cutter disks use custom metallurgy to achieve maximum penetration in very hard rock, which minimizes the need to change cutters while boring through various abrasive rock formations. Two roof drills mounted on the TBM are designed to install 8-foot-long rock bolts radially from the crown to spring line. The machine has another drill for probe drilling, which can rotate 360 degrees around the main beam and drill 97 feet ahead of the TBM.

To negotiate relatively sharp turns, the machine uses a two-conveyor muck-removal system made up of 49-foot-long conveyor from the TBM to an 8-foot-long transfer conveyor and a continuous conveyor hopper.

High carbon levels indicate poor plant efficiency, which requires additional fuel and produces higher emissions of pollutants such as sulfur dioxide and nitrogen oxide. Ash that contains too much carbon is also harder to sell to secondary markets as a substitute for portland cement in concrete production, burdening power plants with landfill costs.

Traditionally, carbon has been measured manually. This requires taking an ash sample, weighing it, heating it in an ashing oven to burn off the carbon, reweighing it, and repeating the process until there is no weight change, which indicates all the carbon has been removed. "This process can take many hours and offers opportunity for error," said Brown, who is also director of Iowa State's Center for Coal and the Environment.

The carbon monitor Brown developed can determine carbon content in 5 minutes. An operator deposits a 1-milligram sample of ash into a stainless-steel test container about 1 centimeter in diameter. A low-power laser is focused on the sample, heating the carbon, which generates a minute sound wave. The sound wave is detected by a sensitive microphone mounted above the sample.

The correlation between the sound level and the amount of carbon is analyzed by a microprocessor in the monitor, which displays the percentage of carbon present in the sample. The monitor, which has been licensed by Ametek Inc. in Pittsburgh, has been successfully tested on a variety of coal ashes.

Even incremental improvements in coal-fueled power plants can have major economic and environmental impact, Brown said. For example, a 0.5-percent increase in combustion efficiency at a 500-megawatt plant, which can serve the residential needs of 250,000 people, would mean an annual fuel saving of $377,000 and reduce emissions of nitrogen oxide and sulfur dioxide by 66 and 113 tons per year, respectively.

Bell Helicopter Textron Inc. in Fort Worth, Tex., and Boeing Helicopter Co. in Philadelphia have decided to produce a downsized commercial version of their V-22 Osprey military tilt-rotor aircraft--a hybrid of helicopter and airplane technologies. The move represents an effort to gain consumer acceptance for the unusual Bell Boeing 609 tilt-rotor aircraft, which has large propellers that swivel from the horizontal--used for high-speed forward flight--to the vertical for takeoffs, landings, and hovering.

The pressurized Bell Boeing 609, each of which will carry nine passengers, is to cost less than $10 million; a comparable-capacity helicopter would cost $5 million to $7 million, while a nine-passenger fixed-wing aircraft is priced at about $4.5 million. Powered by twin 1,000-kilowatt Pratt & Whitney Canada PT6 turbine engines, the civil tilt rotor will have a range of 500 miles and a cruising speed of 275 nautical miles per hour. Helicopters fly half as fast and have ranges of about 150 miles.

Market research indicates that as many as 1,000 hybrid aircraft could be sold over two decades for use in medical emergency evacuation and rescue missions, to service offshore oil platforms, and as corporate aircraft. The 609 is also designed as a military trainer that is one-fourth the cost of the larger $39 million Osprey. Studies said that a 40-seat version appears to hold the greatest sales potential, as it could be used to transport passengers between larger domestic hub and international airports as well as smaller commuter airports.

Bell and Boeing have worked jointly on the V-22 Osprey military tilt rotor for 14 years. Sales of the multirole craft are expected to be made to the U.S. Navy, Marines, and Special Forces for missions requiring fast ingress and egress. Though intriguing in its unique design and possible uses, the tilt-rotor aircraft has been costly and time-consuming to develop. The craft was originally too heavy, but more recent development of higher power-to-weight engines and lightweight but strong composite materials have made production possible.

The new brace, developed by Michael D. Shadoan and Neill Myers of NASA's Marshall Space Flight Center in Huntsville, Ala., is secured to the leg by Velcro straps above the knee and a stirrup around the shoe. Cables sheathed inside the stirrup run up the brace to the joint mechanism around the knee.

When the brace wearer steps down and places weight on a heel-strike mechanism attached to the shoe, a lever on that device pulls on the cables, engaging cams in both upper and lower housings of the joint. The cams press against plates in the upper housing that force the two sections together, locking the joint into position.

The knee brace automatically unlocks when the wearer leans or steps forward, releasing the load from the ankle mechanism. Rubber surfaces on the joint are coated with Viton, a fluoroelastomer also used for sealing NASA O-rings, to increase friction for locking torque.

Other brace designs must be locked into the straight-leg position and call for a manual release lever, restricting leg motion. According to Shadoan, an aerospace engineer at Marshall, the new device can lock in any position as long as the foot bears weight, but lets the knee move freely at other times to exercise muscles. "It will slowly allow someone who is rehabilitating to get enough added support and get his or her leg strength back."

The selectively lockable brace, he added, can be calibrated for patient weights ranging from 70 to more than 200 pounds. NASA is working with Horton's Orthotic Lab Inc. in Little Rock, Ark., for field tests on the device prototype.

The riblets are barely perceptible to the touch, and they appear like a matte finish on the aircraft skin. People have nicknamed the material "shark skin" because of its similarity to the predator's drag-cutting outer envelope.

One airline, Cathay Pacific, has begun the most extensive examination to determine whether the riblet skin will adhere properly over the long term and achieve its fuel-burn goal. The film has been applied to about 30 percent of the surface of an A340-300 airliner, which is regularly flying long-haul routes. Cathay Pacific's airplane has the 3M film on the upper wing surfaces, part of the upper fuselage, and both sides of the vertical stabilizer and tail plane. The experiment could last from one to five years.

Lufthansa already has an A340 with a single 3- by 51/2-foot patch of riblets attached to it. Its test focuses on whether the skin will stay on and whether there are any long-term maintenance drawbacks. The German airline has shelved plans to expand its testing because it takes seven days to apply the film to an airplane, having deemed the lost revenue to be too high.

Previous in-house experiments by Airbus engineers showed that the material met its fuel-consumption-reduction goals, but the shark-skin foils of that time began to turn yellow and were difficult to remove, according to Klaus Schneider, Airbus deputy department manager for structures.

The Cathay Pacific A340 airliner will be used to test the latest film, which was developed for improved durability. Besides proving it can save fuel, the aircraft skin will have to show it can withstand air pollution and ultraviolet light.

The U.S. Army has allocated $6 million to support research efforts at the California Institute of Technology, Duke University, the Georgia Institute of Technology, Ohio State University, and Stanford University that will evaluate new electronic surveillance measures against concealed land mines. The mine-finding technologies including chemical sensors, detectors based on radar, magnetism, infrared light, and sound, as well as advanced sensor information processing.

Sandia National Laboratories in Albuquerque, N.M., has opened its new $33 million facility for intelligent systems and robotics research and development. The Robotic Manufacturing Science and Engineering Laboratory will serve as home for the 150 researchers at Sandia's Intelligent Systems and Robotics Center, the nation's largest robotics R&D program. Recent projects by the center's staff have focused on such applications as manufacturing, remediation of hazardous-waste sites, and battlefield robots.

The Lewis Research Center in Cleveland has awarded cooperative agreements to two companies under NASA's General Aviation Propulsion Program. Williams International in Walled Lake, Mich., received a four-year, $37 million contract to develop and demonstrate low-cost, environmentally friendly turbine-engine propulsion systems for light general-aviation aircraft (with up to six seats and cruising speeds greater than 200 knots). The other agreement, for $9.5 million over three years, went to Teledyne Continental Motors in Mobile, Ala., to develop an intermittent combustion engine for single-engine, four-seat general-aviation craft with speeds under 200 knots.

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© 1997 by The American Society of Mechanical Engineers