Technology Bulletin 166

DN Staff

October 23, 1995

8 Min Read
Technology Bulletin

Blue lasers, LEDs promise to double CD-ROM capacity

Blue semiconductor lasers and light emitting diodes may significantly improve CD-ROM storage capability. A computer-industry consortium including Hewlett-Packard, Xerox, American CrystalTechnologies, and Advanced Technology Materials recently received $4 million from the Advanced Research Projects Agency to develop the technology. The wavelength of the light reading a disk is a critical factor in determining available storage. CD-ROM drives currently use red laser technology; blue light's shorter wavelength is capable of reading a smaller area on the disk. Gregory Lindholm, chief financial officer at consortium-member company SDL, Inc., says, "As we went from infrared to red, the industry doubled data density. As we go from red to blue, we will double the density again." Today, using Motion Picture Experts Group (MPEG) compression, a standard CD offers some 70 minutes of video. A blue-light-based CD-ROM reader will handle two-hour movies with full audio on a single disk, consortium representatives say. Blue LEDs based on gallium nitride materials have already been demonstrated, but blue semiconductor lasers are just now in process, and a specific blue light CD-ROM reader is still years away, says Lindholm. Printing, data storage, medical technology, and displays also may benefit. For details, FAX SDL at (408) 943-1430.

Ceramic composites boost furnace energy efficiency

A processing technique for making continuous fiber ceramic composites (CFCCs) promises to improve operating performance and reduce costs for furnace tubes and gas turbine combustors. Textron Specialty Materials (TSM), Lowell, MA, recently received a $4.2 million contract from the U.S. Dept. of Energy to pursue development of the technique, which impregnates and coats the tubes for better durability. An aluminum holding furnace with CFCC immersion tube heaters is currently demonstrating the technology at a large aluminum die-casting facility. Direct heating of molten aluminum with immersion tube heaters provides greater efficiency and lower contamination than radiant heating methods, say TSM engineers. They estimate that the use of ceramic tubes in heat-treating furnaces could save $170 million annually in fuel costs; using the tubes in reformers may result in a 20% reduction in hydrocarbon feed-stock use. For more information, FAX Bruce Thomson at (508) 934-7597.

Composite forceps could make infant delivery safer

Composite materials and fiber-optic sensing may soon be at work in hospital delivery rooms. NASA's Marshall Space Flight Center, Huntsville, AL, recently signed a Space Act Agreement with the Collins Clinic, Slidell, LA, to redesign the obstetric forceps used to position an infant in a mother's womb. Researchers hope to identify a composite for the forceps and design instrumentation to measure the forces being applied to an infant during delivery. "Metal forceps currently used don't allow the attending physician to assess the force the instrument is placing on the infant," says Dr. James Collins. Currently, obstetricians must acquire a "feel" for their instruments during actual deliveries. The instrumented forceps will allow obstetric students to learn to use forceps within safe limits before entering practice. NASA instrumentation will allow engineers to embed fiber-optic sensors in the composite material. This will help ensure a safer distribution of pressure and allow the doctor to monitor forces on the infant throughout delivery, says design engineer Stan Smeltzer of Marshall's Structures and Dynamics Laboratory. Engineers hope to complete the new design early next year. FAX NASA's Technology Transfer Office at (205) 544-3151.

Ferroelectric chips promise speed and nonvolatility

Engineers at Toshiba Corp., Tokyo, and Ramtron, Colorado Springs, plan to develop ferroelectric random access memory (FRAM) chips that are able to retain data stored in memory when power is removed. FRAM memory devices offer the same high speed as DRAM and SRAM chips and the nonvolatility of ROM: "The best of both worlds," say Ramtron engineers. Such features lend themselves to application in small, portable electronic products, say Toshiba engineers. "They will be used in devices such as personal digital assistants because they can be driven at low power, low voltage, and they are fast," says Toshiba's Makoto Ueda. "They are nonvolatile so they don't need to be powered all the time." While nonvolatility is already available from devices such as EEPROM and flash memory, Ramtron engineers say FRAM chips require much less power to operate and offer higher speed programming. The new chips can also handle more rewrite cycles before wearing out. The firms hope to introduce samples in 1997. Mass production in the future will result in prices for the chips falling to around the same price as conventional memory, predicts Toshiba. For details, FAX Ramtron at (719) 488-9095.

Silicon micromotors drive external gears

Imagine a pollen-sized gear meshing with one 30 times larger, and driving it. Thanks to engineers at Sandia National Laboratories, Albuquerque, NM, you don't have to imagine it. They claim their millimeter-square silicon micromotor is the first to drive external gearing and be built entirely by microelectronic fabrication techniques. Because it is made with etching processes and silicon materials already in use by the microelectronics industry, engineers hope that mass-production of the motor will be relatively easy. The motor uses three levels of polycrystalline silicon: The first contains the engine, the second the gears that the engine drives, and the third the linkages that connect the engine to gears or other linkages. The motor develops 0.5 microwatts of power delivered through a gear 50 microns in diameter. The motor may be used to operate micromedical pumps that function as drug-delivery systems inside the human body, or as low-cost, high-performance gyroscopes for automotive and military use. For details, FAX Sandia at (505) 844-6367.

This sucker could improve robot control systems

The mobility of leeches has prompted researchers at the Georgia Institute of Technology (GIT) and Emory University to build circuit models of the slippery creature's nervous system. "If we can learn how to model these biological systems, we may be able to use that knowledge to build better pumps, better motor control systems for robots, and--further down the road--better prostheses for humans," explains Steve DeWeerth of GIT's School of Electrical and Computer Engineering. DeWeerth and his colleagues are using neuromorphic analog VLSI circuits to model the leech's circulatory and swimming systems. "Neuromorphic" means the analog circuits are modeled after biology. Researchers targeted the leech because of its manageable number of neurons, and because the regularity of the creature's segmented structures make it a suitable modeling aid. In the future, researchers hope to incorporate the electrical systems they build into a larger one, including sensor feedback. For details: ccss (Internet) .

Unpiloted aircraft sets new solar-powered altitude record

A NASA remotely-controlled aircraft, using solar energy to fly to stratospheric altitudes, achieved a milestone flight demonstration last month that could lead to better understanding of the upper atmosphere and the effect of greenhouse gases on Earth's environment. The Pathfinder aircraft, developed by AeroVironment Inc., Monrovia, CA, is one of several unpiloted prototype vehicles under study by NASA. The flight at NASA's Dryden Flight Research Center, Edwards, CA, was the first in a series of high-altitude tests. During the nearly 12-hour mission, engineers piloted Pathfinder from a ground station to an altitude of 50,500 feet: a new record for solar-powered aircraft. The all-wing aircraft weighs less than 600 pounds. The NASA-industry alliance is also examining lightweight materials, avionics, sensor technology, aerodynamics, and other forms of propulsion suitable for extreme altitudes. Pathfinder was carrying four small payloads: a device to collect aerosol-size data, a solar cell calibration computer, a Navy communications relay unit, and a strain-gauge package to collect data on Pathfinder's composite structure. Previous holder of the solar aircraft record of 14,000 feet was the Solar Challenger, also built by AeroVironment Inc. The company also developed the human-powered Gossamer Condor and Gossamer Albatross. For details about the Pathfinder, FAX AeroVironment at (805) 581-4512.

Wanted: Innovative ideas for fluoropolymers

Your concept for a new way to use fluoropolymer resins could win you an Apple(R) Newton(TM) Personal Communicator. AlliedSignal wants to hear your ideas for applications of their ACLON(R) resins: the basic raw material for fluoropolymer films and coatings. The resins allow custom processors to create non-film shapes such as sheet, rod, tube, and profile. ACLON fluoropolymer aqueous-base dispersions can be applied as coatings to fabric, films, metals, and other substrates. ACLAR(R) fluoropolymer films answer many critical packaging and industrial challenges, say AlliedSignal engineers. All three fluoropolymer forms share common properties, such as moisture barrier protection, chemical resistance, clarity, and transparency to UV radiation. AlliedSignal will award three Personal Communicators to the most promising submissions. For details, FAX (800) 377-7681.

'Intelligent' seal could reduce rocket-engine weight

An electronically controlled mechanical seal designed by engineers at the Georgia Institute of Technology (GIT) and NASA's Lewis Research Center promises to increase the payload capacity of liquid-fueled space vehicles. The new design uses a thin carbon face bonded to a piezoelectric crystal that deforms in proportion to the electrical voltage applied to it. When attached to one face of the seal, the crystal will adjust the spacing between critical moving parts in a rocket engine's turbopump. A closed-loop control system will constantly monitor conditions within the seal and determine the proper voltage to maintain clearances. The technique reduces the weight associated with current floating-ring seals used to keep hot exhaust gasses away from liquid oxygen. The new seal combines the high reliability and low wear-rate of floating-ring seals with the low leakage rate of mechanical face seals, says Richard Salant, professor of mechanical engineering at GIT. He predicts that the seal design could find use in feedwater pumps in factories, in coolant pumps in nuclear power plants, or as pipeline seals in unmanned pumping stations. For details, FAX Salant at (404) 894-8336, email Richard.Salant

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