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Photo: Greg Grieco |
By A'ndrea Elyse Messer
Public Information
Thinner laptop computers and flat-screen TVs may be possible with a simple change in the geometry of piezoelectric transformers that can increase the conversion ratio without adding volume or weight, according to researchers.
"Conventional electromechanical transformers are big, very heavy and produce a great deal of magnetic noise that, without shielding, can wipe floppy disks, tapes and hard drives," said Kenji Uchino, professor of electrical engineering and member of Penn State's Materials Research Laboratory. "Rectangular piezoelectric ceramic transformers have been commercially in use since 1994 especially for computer notebook applications. Our circular configuration, made with improved materials, advances this field and opens the way for more powerful, lightweight transformers."
Electromagnetic transformers consist of two coils of wire that convert high voltages to lower ones or low voltages to higher ones. The size of the step-up or step-down depends on the difference between the number of turns of wire in each coil. Large electromagnetic transformers are very efficient, but miniaturization decreases the efficiency.
Uchino; Burhanettin Koc, postdoctoral associate in electrical engineering; and Yongkang Gao, graduate student in materials science and engineering, worked on disk shaped transformers made of an enhanced piezoelectric material consisting of a lead, zirconium and titanium ceramic doped with manganese and cerium.
Uchino collaborated with NEC Corp. in Japan in developing the rectangular piezoelectric transformers currently in use in their notebooks, but the circular wafers promise increased efficiency and higher conversion ratios.
In the circular wafer, about one-third of the wafer is used for a crescent shaped input electrode with the remaining two-thirds as output. The disk transformer provides a voltage step-up ratio of about 60 rather than the rectangular rate of just over 40 because it uses more than one vibration mode. The circular wafers take up the same volume and weigh the same as rectangular transformers.
Piezoelectric material moves when under an electric current, and when displaced by outside pressure, these materials produce an electric current.
"Piezoelectric transformers are not only more efficient, smaller and lighter, but they also are much less expensive to manufacture than conventional coil wound transformers," said Uchino.
He warns, however, that piezoelectric transformers are not necessarily the answer to all power problems. For one thing, in any transformer, as the voltage is increased, the current decreases, so transformers are only applicable where current is unimportant. Also, piezoelectric transformers have only been tried in a few applications, and there may be unforeseen problems with their use.
Every person on the planet needs water to survive, but an engineer in the College of Agricultural Sciences said consumers should know where to go for a water test, as well as what tests to ask for before taking their first sip from a new water supply.
"Many people only test their water if something is visibly wrong or if they get sick," said Paul Robillard, associate professor of agricultural engineering. "In fact, it's a good idea to test the water before or right after purchasing a house, or if homeowners have never tested their supply."
Robillard said the majority of homeowners using a municipal water supply receive water that already has been treated and disinfected.
Most homeowners not served by municipal systems use wells, natural springs or roof cistern systems to supply their water needs. Robillard estimates there are about 900,000 wells in Pennsylvania and that 80 percent of individual water-system owners use wells.
"The individual is totally responsible for managing the quality of a private system," Robillard said. "If a home has a well or another type of water system, the homeowners should have it tested as soon as they move in."
Robillard emphasizes that homeowners should have their water tested by a certified analytical lab. Tests cost from $20 to $50, depending on what tests are needed.
At a minimum, testing of private systems should include:
n Microbiological. The presence of coliform bacteria (including E. coli 0157:H7) is an important overall indicator of water contamination. Yearly testing is recommended.
n Nitrate-N. Nitrate-Nitrogen, a common groundwater contaminant in agricultural areas, is a potential health problem when consumed by infants. This contaminant is both "conservative" and "mobile," which means it does not degrade in the soil-water environment and is efficiently transported in subsurface and groundwater flows.
n Total Dissolved Solids. This test is an overall indicator of water quality, representing the extent to which minerals and salts are dissolved.
n pH levels. This test can provide information about potential water problems such as corrosivity or aggressive water.
For more information, contact Marsha Hull at (814) 865-7685 or mxh16@psu.edu; or access the agricultural and biological engineering Web site at http://www.age.psu.edu/
Kenji
Uchino, professor of electrical
engineering, above, and colleagues have found that disk-shaped transformers
made of an enhanced piezoelectric material such as the one shown at left,
result in thinner laptop computers and flat-screen televisions.