Scientists at Princeton
University are composing
the complex codes designed to instruct a new class of powerful computers that
will allow researchers to tackle problems that were previously too difficult to
solve. These supercomputers, operating at a speed called the
“exascale,” will produce realistic simulations of complex phenomena
in nature such as fusion reactions, earthquakes, and climate change.
The capacity to deploy computations at such an extreme scale could put
scientists closer to solving a wide range of research problems, including the
quest to make fusion energy a safe, affordable power source, according to
William Tang, head of the Fusion Simulation Program at the U.S. Department of
Energy’s Princeton Plasma Physics Laboratory (PPPL). The new computing power
would also greatly enhance the realism of simulations used in that research.
In recognition of the prospects for faster progress in the understanding of
complex scientific issues—and as part of a new international collaboration—the
Group of Eight’s (G-8) Research Councils Initiative on Multilateral Research
Funding has awarded grants to Tang and two other Princeton-based scientists: Jeroen
Tromp, a geophysicist; and Venkatramani Balaji, a climate modeler. All are
focused on helping to develop the advanced software that will put the coming
new generation of computers to work on solving problems of global interest.
“What we hope to demonstrate is that this focused level of
international scientific collaboration can help deliver breakthrough payoffs in
high-performance computing,” said Tang, who is also a member of the
executive committee of the Princeton Institute for Computational Science and
Computers approaching the exascale possess the capability of doing a quintillion
calculations at once. Approximately a quintillion pennies laid out edge to edge
would cover the surface of the Earth twice.
The three-year awards for the Princeton
researchers are part of a pilot program established by the G-8 in 2010 to
foster multinational collaboration among scientists. The G-8 is an organization
involving leaders of some of the world’s largest industrialized nations,
including Canada, France, Germany,
Italy, Japan, Russia,
the United Kingdom, and the United States.
“There is recognition that science is international in scope and that
there is an advantage to scientists from different countries partnering
together,” said Marc Rigas, staff associate for planning and coordination
of the Office of Cyberinfrastructure at the National Science Foundation, which
selected and funded the U.S.-based grantees for the G-8 council.
The Princeton grants are among six winning
proposals selected from 100 international applicants’ submissions. All the
projects require partnering with scientists from other G-8 nations. According
to Tang, the grant selections were made after an intense peer review process.
Understanding fusion reactions
Tang intends to use his $470,000 grant to develop advanced simulation codes
that will be compatible with the emerging class of supercomputers. The goal of
his project, known as NuFuSe, is to produce higher-fidelity simulations of the
physics behind fusion reactions. That will mean solving problems it would not
be possible to address in a timely way using present-day supercomputers.
Working with researchers in the U.K.,
France, Germany, Japan,
Tang hopes to learn how to better control the behavior of magnetically confined
fusion plasmas. Though fusion reactions are responsible for energy release in
the universe, harnessing fusion as a clean and sustainable supply of energy on
Earth is a major scientific and technological challenge. It has commanded the
attention of researchers at laboratories worldwide, including PPPL.
Fusion reactions are produced in experimental devices in which isotopes of
hydrogen are heated and contained in a magnetic field. When these charged hydrogen
particles are confined long enough at temperatures that exceed 10 million
degrees, a large amount of energy is produced. However, the hot plasmas can
behave erratically, a phenomenon known as microturbulence. Such an event can
accelerate heat loss and compromise the efficiency of the reaction. Tang noted
that “it is the balance between these heat losses and the self-heating
rates of the fusion reactions which largely determines the size and cost of a
As part of the quest to build efficient fusion power plants, Tang envisions
using the new exascale computers to create sophisticated simulations of fusion
reactions to gain new insights into how to reduce the heat losses brought on by
The international cooperation required by the G-8 council will have another
benefit, Tang said. The research partners will be collaborating instead of
working in separate silos. For example, new software developed within the
international project could be tested on the collaborating partners’
supercomputers. The grant will cover the salary of a postdoctoral student along
with some travel expenses so research staff can attend conferences.
Organizing climate data
For his project, Balaji—head of the modeling system group in the University’s Program
in Atmospheric and Oceanic Sciences and the National Oceanic and Atmospheric
Administration’s Geophysical Fluid Dynamics Laboratory on the Forrestal Campus—is
planning to use his $313,000 G-8 grant to design software that will organize
the huge but unmanageable archives of climate data from around the world.
Producing accurate forecasts of a changing climate, especially on the
regional scale, is of vital interest to those managing impacts on the environment
and public health. For instance, “a scientist at work on malaria might
want to know how many mosquitoes are likely to be in a region in the future,
which means predicting temperature or humidity,” Balaji said.
Complicating matters, different research groups have constructed different
mathematical models to use in making such predictions, he added. There is a
“giant data archive” that exists. But, with 20 different models in
use, he said, scientists could come up with 20 different predictions. “We
have to run them all and make an average, but then the problem is the data is
now in 20 different places,” he said.
There is currently enough data out there to “predict the temperature
in Burkina Faso
25 years from now,” Balaji said, “but you would need to analyze
probable outcomes from many models and multiple scenarios of how society might
change.” It will take exascale computing to make that happen, he noted.
His group is developing computer language that would instruct powerful
computers to coordinate and streamline such an analysis.
“The G-8 gives us a unique opportunity to have science agencies around
the world work together,” Balaji said. He will be working with peers in Canada, France,
Germany, the United Kingdom, and the United States.
Mapping the Earth’s interior
In a similar approach, Tromp, the Blair Professor of Geology and director of
PICSciE, will use his $500,000 grant to further his work mapping the interior
of the Earth. Using data from seismograph readings from all over the globe,
Tromp and colleagues in Canada
construct computer images showing the structures underneath the Earth’s crust
to a depth of 700 km. The images make pre-human history come alive.
Tromp, a professor of geosciences and applied and computational mathematics,
noted that, for example, with a newly created image for Europe “we can see
the subduction of Africa, see that slab being pushed into the mantle; we can
see old and recent volcanism in the Czech Republic, and how Italy has rotated
counterclockwise over the last 6 million years to where it is today.”
Tromp and his colleagues are also known for taking seismographic findings
and turning them into earthquake simulations, known as “ShakeMovies.”
Though earthquakes cannot be predicted, he said, the virtual earthquakes help
assess potential hazards so that engineers can build structures to withstand
Tromp sees the G-8 approach to funding multinational collaborations as
“a wonderful model for computational science.”
“This is how modern science should be conducted,” he said.
Source: Princeton University