9/10/02 -- NAS Scientist Receives International Award
Senior scientist Deepak Srivastava recently received the Eric Reissner Medal for distinguished work in computational nanosciences. The medal, awarded in August at the International Conference on Computational & Experimental Engineering and Sciences (ICES), cites Dr. Srivastava's "distinguished work in computational nanosciences and carbon nanotubes."

The award by an international forum of scientists and engineers recognizes Srivastava's contributions in broadening the understanding of the nanomechanics and electronic behavior of carbon nanotubes. It also signals an international acceptance of nanotechnology as the next growth area in the broader scientific and engineering communities.

Srivastava is technical lead of the NASA Advanced Supercomputing (NAS) Division's computational nanotechnology investigations. His work has concentrated on computational nanotechnology in nanomaterials, nanoelectronics, and nanodevices. Possible applications include ultra-strong, light-weight composite materials and molecular electronics devices for computing and sensing purposes, as well as concepts and materials for solid-state quantum computers.

Srivastava's new focus area will include state-of-the art implementation of simulation algorithms on NAS supercomputers, in a user friendly way. Srivastava hopes this area of research will pave the way for NAS to become a service provider for simulations in nanomaterials and molecular electronic devices and systems to other NASA centers, and to industry and university customers.

The NASA Ames' nanotechnology program is playing a significant role in steering nanotechnology developments both within and outside NASA.

The Eric Reissner Medal is awarded every two years by ICES for excellence in computational mechanics research. Reissner (d.1996) was a noted teacher, researcher and author, who expanded the foundations of the theory of mechanics, leading to advances in the design of both civil engineering and aerospace structures.

For more information on the NAS Division's work in nanotechnology, contact Deepak Srivastava at (650) 604-3486, deepak@nas.nasa.gov.

8/13/02 -- NAS Division Sets Standard for Grid Benchmarking
Growing eagerness for grid computing in the business and research communities has prompted the Global Grid Forum (GGF) to turn to NAS scientists for guidance measuring grid efficiency and user-friendliness. Michael Frumkin and Rob Van Der Wijngaart recently received approval from the GGF to establish a formal research group on grid benchmarks.

Official approval means the scientists can hold regular sessions at GGF workshops and continue their work developing grid benchmarks in collaboration with other organizations interested in developing global grid standards.

“Benchmarking is a long-standing trade at NASA,” explains Van Der Wijngaart, adding, “Computational grids are really at the same stage as parallel computers were about 10 or 15 years ago. Frumkin and Van Der Wijngaart decided to use the highly respected NAS Parallel Benchmarks as building blocks to construct more complicated tasks on computational grids.

So far, NAS scientists have defined four model grid applications, derived from common NASA operations, such as flow visualizations and parameter studies. For each of these applications, they have provided exact specifications, resulting in the NAS Grid Benchmarks (NGB).

Allan Snavely, Performance Modeling and Characterization Laboratory leader at San Diego Supercomputing Center, says that his group also recognized that the lack of ways to measure grid performance posed problems for grid developers. “We have a window of opportunity to develop grid metrics and influence the design of grid systems in a very positive way,” says Snavely. Snavely will co-chair the GGF research group with Van Der Wijngaart.

Frumkin is optimistic that grid benchmarks will generate useful results and guide tool developers to write more efficient code. “When the NAS Parallel Benchmarks were released, everyone tried to show that their machine was better because it took less time to successfully execute the benchmarks. We are expecting the same thing to happen with the grid benchmarks.”

For more information on the NAS Grid Benchmarks, contact Rob Van Der Wijngaart at wijngaar@nas.nasa.gov.

7/23/02 -- Nanotube Researcher Challenges Well-known Findings
A new take on a well-known nanotube experiment was recently published by NAS Division researcher Toshishige Yamada in Applied Physics Letters (May 2002). Yamada's paper, "Modeling of Kink-Shaped Carbon-Nanotube Schottky Diode with Gate Bias Modulation," challenges findings of a gate voltage modulation experiment by a research group at Delft University of Technology, The Netherlands.

In 1999, the Delft researchers published the first experiment clearly demonstrating that a transistor action principle called the “gate modulation effect” survives at the atomic scale as an intermolecular device made of up only of nanotubes. However, the team could not conclude whether the nanotube was p-type (positive-carriers rich) and where the rectification took place. Yamada analyzed their data and clarified that the nanotube must be n-type (negative-carriers rich), rather than p-type, as was previously believed. He also showed that rectification occurred at the kink part of the nanotube, rather than at the electrode contact.

Yamada’s work is meaningful from a pure physics standpoint, and helps solve a key issue in semiconductor electronics. All semiconductors are either p-type or n-type. Today’s semiconductor electronics require a sophisticated combination of both types to create transistors. “Knowing whether a semiconductor is either p-type or n-type is the first step towards nano-transistors and nano-electronics,” explained Yamada. “The next issue to tackle is why the Delft group had an n-type nanotube, while others are seeing p-type nanotubes routinely in their laboratories.”

Other experimental nanotube devices fabricated in research labs have all been hybrids of a semiconducting nanotube and macroscopic metallic electrodes, and will not guarantee the smallest miniaturization, according to Yamada. His paper shows that the Delft device made solely of nanotubes operated with the same transistor action principle used in today’s devices, and strongly suggests the feasibility of an "all nano-material transistor" in the future.

For more information, contact Toshishige (Toshi) Yamada, at yamada@nas.nasa.gov, (650) 604-4333.

7/09/02 -- HiMAP Software Wins Space Act Award
A team led by Guru Guruswamy of the NASA Advanced Supercomputing (NAS) Division at Ames Research Center, recently received the 2002 NASA Space Act Software Release award for developing HiMAP, the High Fidelity Multidisciplinary Analysis Process. HiMAP software efficiently integrates software analysis tools to solve large-scale multidisciplinary problems on massively parallel supercomputers.

HiMAP integrates disciplines with diverse physical characteristics by retaining the efficiency of individual disciplines. Results are demonstrated for large-scale aerospace problems on several supercomputers. HiMAP has been successfully used by NASA's High Speed Civil Transport (HSCT), the Defense Advanced Research Projects Agency' Unmanned Combat Air Vehicle project, the Navy's Abrupt Wing Stall project, and Boeing's and Lockheed Martin's Internal Research and Development projects.

"Anticipated savings over the next fiscal year to a number of aircraft programs is expected to be in the $100,000s. The added analysis capability due to the (HiMAP) software provides a capability that previously did not exist within NAVAIR," said Dr David Findlay, Manager, Naval Air Systems Command. Engineers at Sun Microsystems have ported HiMAP to the latest parallel systems running Sun HPC ClusterTools™ 4 Software.

HiMAP technology could prove useful in other fields such as automotive, mechanical, civil- and bio-engineering, where analysis of fluids/structures interactions play important role. Future potential applications include analysis of floating runways (similar to that under consideration at San Francisco airport), modern cable-stayed girder bridges, and human hearts.

For more information contact Guru Guruswamy at gguruswamy@mail.arc.nasa.gov, (650) 604-6329.