Special Features:
SHAKING THINGS UP WITH
NEESGRID
By Tom Garritano
One of the GRIDS Center's target communities is NEES, the George Brown,
Jr.,
Network for Earthquake Engineering Simulation. Funded by the National Science
Foundation (NSF), NEES is a distributed virtual laboratory for earthquake
experimentation and modeling. Its users are researchers who seek to design
buildings and other structures that are more resistant to seismic events and
disasters in general.
An ambitious aspect of NEES called NEESgrid is a networked infrastructure
that
facilitates integration of diverse systems such as instrumentation (including
huge shake tables, centrifuges and tsunami wave tanks), computational
resources and collaborative environments. Several principal investigators from
the NSF Middleware Initiative (NMI) GRIDS Center are also prominent members of
the NEESgrid team. This overlap is helping to speed up progress by NEESgrid,
which is building its applications on the GRIDS Center Software Suite (www.grids-center.org).
Because NEES and NEESgrid are scheduled to operate through 2014, they
represent a long-term NSF commitment to using the Grid for earthquake
engineering. GRIDS is also partnered with other NSF investments like the Grid
Physics Network (GriPhyN) and TeraGrid to provide a stable substrate of
middleware on which such communities can build custom applications.
Collectively, they form the front line of "cyberinfrastructure" envisioned in
the recent report (
www.cise.nsf.gov/news/cybr/cybr.htm) of a blue-ribbon panel that advocates
substantial new funding for NSF to stimulate projects across all science and
engineering disciplines, with activities like NEES, GriPhyN and TeraGrid as
models.
Prior to the 2001 advent of NMI, research communities like NEES might have
struggled to create their own separate IT infrastructures, with redundant
efforts and a lack standardization. Through NMI, NSF funded the GRIDS Center
to create a more uniform middleware infrastructure upon which communities can
build their own applications, achieving efficiency and interoperability that
wouldn't otherwise be possible. The GRIDS suite provides NEES with a
long-term, sustainable base for the continued evolution of NEESgrid systems
and software.
Building on GRIDS software, NEESgrid developed telepresence capabilities to
permit remote observation and participation in experiments. This lets
researchers view multiple data or video streams and interact with colleagues
or equipment during real-time tests at multiple NEES equipment sites. NEES
engineers will also have access to a repository of data from experiments and
simulations, in addition to a simulation software repository.
Gokhan Pekcan is the main contact between NEES researchers and the NEESgrid
Systems Integration (SI) team. An earthquake engineer in the Department of
Civil Engineering at the University of Nevada, Reno (UNR), he works with Ian
Buckle, the university's principal investigator on NEES. With Oregon State
University (OSU) and Rensselaer Polytechnic Institute (RPI), UNR is an early
adopter among the 15 NEES sites that are "Grid-enabling" their resources. They
have deployed the NEESgrid Software Suite, including GRIDS components like the
Globus Toolkit and Condor-G, as fundamental infrastructure for data
acquisition, analysis and archiving.
"We are using the GRIDS distribution as the base of the NEESgrid software,
and
deployment has gone tremendously well," Pekcan said. "It was difficult at
first because we weren't speaking the same language as the NEESgrid staff.
Before NEES, none of the earthquake engineers was familiar with Grid concepts.
But both sides were determined to communicate well, and that's what has
happened."
They began by defining and acquiring the needed hardware and software
components for NEESgrid. UNR's configuration, which Pekcan said is similar to
other NEES sites, has two servers running RedHat Linux 7.3, with a third
machine running Windows 2000 for data acquisition. Testing began in earnest
with the first NMI and GRIDS release in mid-2002. Concurrently, UNR was
installing its NEES-funded shake tables, which will eventually be accessible
to remote users who will be able to conduct experiments, acquire data and
interact with colleagues dispersed around the world -- all in real time.
NEES is already doing Grid-enabled simulations, and they are working toward
real-time remote collaboration via teleobservation, telepresence, shared data,
test visualizations, system identification, and numerical computations. "We're
laying groundwork for real-time manipulation of shake tables," Pekcan said,
"This progress is relevant to NEES sites with large centrifuges and tsunami
wave basins."
UNR's three shake tables are 14 by 14-foot biaxial platforms with intricate
components pressurized up to 5,000 pounds per square inch. They have a
combined payload capacity of 150 tons to test scale models of bridges and
buildings -- even soil samples -- which are subjected to forces up to 1G in
two directions simultaneously. Each table may operate independently, in-phase
(i.e., with the other two combined to act as a single unit), or differentially
with the other tables to simulate spatial variation effects of
earthquakes.
A major challenge addressed by NEESgrid is the synchronization of
experimental
data and devices. NEES engineers envision having multiple sites run
simultaneous experiments, each dependent on the other. Such dynamic
circumstances mean devices will need to be synchronized at the millisecond
level, which requires an extraordinarily efficient use of network and
computational resources by the underlying middleware infrastructure.
UNR has been able to do most of its own Grid troubleshooting, Pekcan said,
even without computer scientists on staff. Their campus IT support office has
helped troubleshoot network problems, and on rare occasions when the NEES
staff get stumped, he said, the UNR computer science faculty lend a hand.
Now that UNR and other early adopters have done some spade work, the
remaining
NEES sites will benefit from the lessons learned. "There is no doubt we are on
target to meet our milestones," Pekcan said. "Progress is increasingly rapid
as the September 2004 date for a fully operational 15-site NEESgrid
approaches."
GRIDS principal investigators on the NEESgrid team are Ian Foster
(University
of Chicago and Argonne National Laboratory), Carl Kesselman (Information
Sciences Institute at the University of Southern California) and Randy Butler
(National Center for Supercomputing Applications at the University of Illinois
at Urbana-Champaign). Besides those institutions, NEESgrid also includes the
University of Michigan and University of Oklahoma.
In addition to UNR, OSU and RPI, the NEES equipment sites will include
Brigham
Young University, Cornell University, Lehigh University, State University of
New York (SUNY) at Buffalo, University of California campuses at Berkeley,
Davis, Los Angeles and San Diego and University of Texas at Austin. See
www.neesgrid.org.
Tom Garritano can be reached at garritano@mcs.anl.gov.
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