Supercomputing: There’s an App for That

MIT researchers use Ranger to prove the potential of simulation on a small device

Still from a short movie which illustrates a Nexus One phone implementation of the online component of the certified reduced basis method. Note that all computations in the video clip are performed directly on the phone (no communication is involved).

What if you could perform supercomputing calculations in real-time, on your smartphone, in any location?

Researchers at the Massachusetts Institute of Technology (MIT), collaborating with staff at the Texas Advanced Computing Center (TACC), have created an application that does just that.

The team performed a series of expensive high-fidelity simulations on the Ranger supercomputer to generate a small “reduced model” which was transferred to a Google Android smart phone. They were then able to solve problems on the phone and visualize the results on the fly.

The project proved the potential for reduced order methods to perform real-time and reliable simulations for complicated problems on handheld devices.

“You don’t need to have a high-powered computer on hand,” said David Knezevic, a post-doctoral associate in mechanical engineering at MIT working in the lab of Prof. Anthony Patera. “Once you've created the reduced model, you can do all the computations on a phone.”

A screenshot of an engineering application developed by the researchers for the Andriod smart phone.

This is not the first time that model reduction algorithms have been used to ameliorate the complexities of large-scale physical simulations. The advantage of the system designed by Knezevic and his colleagues is its rigorous error bounds, which tell a user the range of possible solutions, and provide a metric of whether an answer is accurate or not. The error bounds are based on mathematical theory developed in Prof. Patera's research group at MIT over a number of years.

“We have a bound on how much accuracy we’re losing with our reduced model, so we can say with rigor that we’re doing supercomputing on a phone,” Knezevic said.

The reduced model is constructed by focusing the supercomputer simulations on a range of parameters that are of interest to the user. Once the construction is finished, the model can be used to perform simulations for new parameters, nearly instantaneously, for use in real-world applications.

“We’re interested in accurate, real-time computing, and the calculations on the phone take less than two seconds,” Knezevic said.

So far the team has developed a number of demonstration problems that run on the system, mainly fluid dynamics, acoustics and heat flow simulations. However, many different problems can be handled with this method.

In its smartphone form, the researchers imagine their method could be applied to “in the field” inverse problems like landmine detection, as well as to design problems like determining the optimal shape for structures.

TACC provided access to Ranger to compute the problems and TACC staff collaborated with Knezevic to debug and parallelize the code so it could scale efficiently to thousands of processors on the system.

“The payoff for model reduction is larger when you can go from an expensive supercomputer solution to a calculation that takes a couple of seconds on a smart phone,” Knezevic explained. “That’s a speed up of orders of magnitude.”

The improvements allowed the team to compute three-dimensional solutions, and to work with the complicated class of non-linear equations in which the researchers were interested.

"After collaborating on the code for several months, it was much more powerful, flexible and efficient," said John Peterson, a research associate in the high performance computing group at TACC and a collaborator on the project.

Using the smart phone application, researchers can change values, improve the error bounds by increasing the complexity of the local calculation, and even visualize the solution interactively in three dimensions.

“It’s demonstrating that with a small processor, you can still get a meaningful answer to a big problem,“ Peterson said.

The real impact of the system may come in the application of these methods to aircraft or automobiles, which use control systems to react to inputs from the environment in order to achieve optimal safety and performance. Examples include traction control in cars and stabilization systems in jet fighters.

“If you have sensors feeding in data to the reduced order model system, then it could solve the equation corresponding to the input data, and indicate the appropriate response in real-time based on the calculations you performed on a supercomputer,” Knezevic said.

“The control system needs a simplified model of the aircraft so that it can make split-second updates to the ailerons and flaps,” Peterson added. “That simplified model is the reduced basis model.”

Creating a lightweight instantiation of this technology in the form of a smart phone application signals many new possibilities for reduced order modeling in applied science and engineering.

Concluded Knezevic: “When you tell people you can solve a problem that would normally take two hours on Ranger in one second, with guaranteed error bounds, people instantly understand what model reduction is all about.”

Published August 17, 2010

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I attended the National Association of Science Writers conference in Austin this week. It was inspirational, but activated some latent fears and frustrations.

The first two talks were about the instability of the journalism market and the potential for multimedia to enrich communications. These were followed by several talks about social media networks and their use in promoting journalism.

The first worries me, because it seems like writers are becoming expendable, or at least much less tied to traditional news organizations. 'Get used to it,' was the bottom line, following by, 'what a time of great opportunities!' I see that, but it's still unsettling.

The second talk troubled me because I miss making movies, devoting time to the visual. I haven't been able to spend much time working on documentaries, for work or outside of work, and I miss the process.

The third talk caused me to realize that I'm not only anti-social in the real world, I'm not anti-social in various virtual worlds as well. Speakers kept imploring us to join and be an active part of virtual communities, and all I can say to that is...I'll try.

By and large, the conference stimulated a lot of ideas and ambitions. Top people, in science and science writing, talking about their passions, their predictions, their processes. It made me want to grow into the next phase of my professional career.

What should this blog be about

It's a toss-up, really. It could be a blabby, life/relationship, gossipy kind of blog. (Probably not.) Or it could be a blog about art and culture and stuff. I'm really into that. (Likely.) Or, it could be about the technology of the future, about the kingdom of the nanobots and 12th dimensional space, based on this strange hightech world that I am currently immersed in. (Also, quite likely.) Or some conflation of the three.

But first, an experiment (image placement). This is me at my best. Expect future pictures to be uglier.

I have such a hard time with titles

Picking names is easy for some people. These people have snappy, appropriate names for their blogs. They have tattoos with apt words written permanently on their bodies. They wouldn't have a hard time coming up with the name of an art exhibition, say, or naming a pet or a company. And yet, for me, these things present problems.

Borges has a great statement about the false simplicity of language: "I have done my best -- I don't know with what success -- to write straightforward stories. I do not dare state that they are simple; there isn't anywhere on earth a single page or single word that is, since each thing implies the universe, who most obvious trait is complexity."

Hence I take: "We Buy Broken Gold" (the existential slogan for endless pawn shops in Texas) as my blog title, hoping to project optimism in the face of disappointment.