Combining the use of multiple voltages with a new
concept that
schedules energy resources Vijaykrishnan Narayanan, assistant
professor of computer science and engineering, and colleagues can
reduce computer circuits' energy requirements.
Photo: Greg Grieco
By Barbara Hale
Public Information
Researchers from Penn State, the University of South Florida and the University of Texas at El Paso have developed and demonstrated a new method for reducing computer circuits' energy requirements -- by more than one-half in some applications -- without cutting down on overall operating speed.
The new approach holds promise for laptop and other personal computing device users worried about their batteries running down, manufacturers who want to make more complex circuits that won't melt in full operation, and wireless communication equipment developers that need dedicated circuits with lower power demands.
Vijaykrishnan Narayanan, assistant professor of computer science and engineering at Penn State, worked with Vamsi Krishna, University of South Florida; and N. Ranganathan, The University of Texas at El Paso.
Narayanan said their approach is based on combining the use of multiple voltages with a new concept, dynamic frequency clocking (DFC), which schedules energy resources on a flexible basis, according to the operations active within a circuit in a particular cycle. Energy is conserved by grouping operations in the most energy-efficient patterns based on the critical path delay, or the time it takes to complete the operation.
For example, Narayanan said, consider a circuit that includes three adders and a multiplier. Adders have a smaller critical path delay than multipliers. Grouping one of the fast adders with the slower multiplier allows the researchers to slow the adder down to the speed of the multiplier without slowing the overall process. To slow the adder down, the researchers supply it with a lower frequency and voltage which conserves energy. Higher voltages make signals propagate down wires faster but require more energy.
The researchers have, so far, performed simulations of their approach for some benchmark circuits particularly useful for signal and image processing computer architectures. They found that, with a suitable choice of voltage levels, their approach produces an average energy saving of 53.5 percent versus the standard, static clocking scheme and single supply voltages.
Currently the research team is investigating using multi-cycling and chaining in conjunction with their approach for further performance improvements.
A
new class of porous materials with an orderly crystal-like arrangement of ultra-small
spherical spaces has been discovered by chemists at Penn State.
The researchers report that they can produce the "nanobubblepack" in a range of pore sizes never before achieved, opening the door to a variety of potential uses in industry and research.
"It looks like we can easily make lots of this porous material out of anything, and we also can fill it up with anything," said Thomas Mallouk, professor of chemistry and principal investigator. "It is intriguing to think about all the ways it might be used."
Co-researchers Stacy A. Johnson and Patricia J. Ollivier, then graduate students, initially proposed the idea for making the material.
"Stacy and Patti were trying to do two things nobody had done before: make organic porous materials using uniform inorganic materials as a template, and make uniform pores in the size range between 10 and 100 nanometers," Mallouk said.
Other researchers had been able to make uniform pores using a fabrication process developed by Penn State materials scientists in the 1970s. They could make either pores larger than 100 nanometers, using polymer spheres as templates, or they could make pores smaller than 10 nanometers, using small molecules or groups of molecules as templates, but they could not make pores between 10 and 100 nanometers because there were no suitable templates in that size range -- bigger than a molecule but smaller than a cell.
The researchers say they can dial in a specific pore size anywhere they want in the previously untouched size range.
"Unlike many other precision materials that are difficult to fabricate, you easily can make pounds of this very-well-behaved stuff," Mallouk said.
Applications for the substance may include more stable and longer-lasting sensors or chemical reactors, like the glucose sensors used by diabetics.
Looking at the types of songbirds in a given area is a good way to assess that area's overall ecological health -- and develop a report card to guide large-scale land use, say two researchers at Penn State's Cooperative Wetlands Center.
Robert Brooks, professor of wildlife and wetlands, and Timothy J. O'Connell, a graduate student in ecology, helped develop a value system for songbirds based on a set of ecological traits. They placed a higher value on species that rely on mature forests and complex food webs over species that thrive in artificially simplified environments like cities and towns.
Brooks and O'Connell used this framework to rate the health of bird communities in central Pennsylvania and extended this analysis to the ecological condition in the Mid-Atlantic Highlands, which includes all mountainous regions in Pennsylvania, Maryland, Virginia and West Virginia.
A random sample of sites in this 68,000-square-mile region showed that 16 percent of the region is in excellent condition; 27 percent is good; 36 percent is fair; and 21 percent is in poor condition. Sites supporting excellent and good bird communities were at least 80 percent forested.
Brooks and O'Connell collaborated in the study with Laura E. Jackson of the U.S. Environmental Protection Agency.
For more information about Penn State's School of Forest Resources, point your Web browser to http://www.sfr.cas.psu.edu/.