Monday, June 1, 2015
HG F30, 10:15 - 11:10

IP1 Simulating Cosmic Structure Formation, Volker Springel (University of Heidelberg, Germany)

Chair: Ben Moore (University of Zurich, Switzerland)

Abstract
Numerical simulations on supercomputers play an ever more important role in astrophysics. They have become the tool of choice to predict the non-linear outcome of the initial conditions left behind by the Big Bang, providing crucial tests of cosmological theories. However, the problem of galaxy and star formation confronts us with a staggering multi-physics complexity and an enormous dynamic range that severely challenges existing numerical methods. In my talk, I review current strategies to address these problems, focusing on recent developments in the field such as hierarchical time integration schemes, improved particle- and mesh-based hydrodynamical solvers, and novel parallelization schemes.

Short Biography
Volker Springel became professor for Theoretical Astrophysics at Heidelberg University in 2010, where he now leads a research group at the Heidelberg Institute for Theoretical Studies (HITS). Springel previously was a group leader in computational cosmology at the Max-Planck-Institute for Astrophysics in Garching, after working as a postdoctoral researcher at the Harvard Center for Astrophysics in the United States. He received his PhD in 2000 from the Ludwig-Maximilian University in Munich, after studying physics at the University of Tübingen and the University of California, Berkeley.

Monday, June 1, 2015
HG F30, 11:10 - 12:00

IP2 The Great Leap, Bjorn Stevens (Max-Planck-Institute for Meteorology, Germany)

Chair: Christoph Schär (ETH Zurich, Switzerland)

Abstract
Increasing computational power and advances in algorithms have made it possible to resolve an ever increasing fraction of the scales of atmospheric motion. While it remains inconceivable to resolve all the relevant scales of motion we are currently in the midst of a great leap across a range of scales that have posed some of the greatest challenges to climate science over the past sixty years. This leap is bringing wholly new insights into the structure of the climate system on both ends of the spectrum of atmospheric motions.

Biography
Bjorn Stevens's research blends modeling, theory and field work to understand the role of clouds and moist convection on the climate system. Stevens has made pioneering contributions to our understanding of how mixing and microphysical processes influence both cloud structure and its susceptibility to changes in the environment. Stevens has contributed more than 130 scholarly articles to the peer reviewed literature and received many honors, including the Clarence Leroy Meisinger Award of the American Meteorological Society for "pioneering advances in understanding and modeling of cloud-topped boundary layer.? He currently co-leads the World Climate Research Programme?s Grand Challenge on Clouds, Circulation and Climate Sensitivity.

Tuesday, June 2, 2015
HG F30, 09:00 - 10:00

IP3 Materials Discovery and Scientific Design by Computation: a Revolution Still in the Making, Giulia Galli (University of Chicago, USA)

Chair: Nicola Marzari (EPFL, Switzerland)

Abstract
The need of advanced materials for sustainable energy resources and next generation information technology requires the development of integrated scientific strategies, encompassing theoretical innovations, and computational and laboratory experiments. Substantial progress has been made in the last two decades in understanding and predicting the fundamental properties of materials and molecular systems from first principles, i.e. from numerical solutions of the basic equations of quantum mechanics. However the field of ab initio predictions is in its infancy; some formidable theoretical and computational challenges lie ahead of us, including the collection and use of data generated by simulations. We will describe recent progress and successes obtained in predicting properties of matter by quantum simulations, and discuss algorithmic challenges in connection with the use of evolving high-performance computing architectures. We will also discuss open issues related to the validation of the approximate, first principles theories used in large-scale quantum simulations.

Biography
Giulia Galli is the Liew Family Professor of Electronic Structure and Simulations in the Institute for Molecular Engineering, at the University of Chicago, Senior Scientist at Argonne National Laboratory and Senior Fellow of the Computational Institute of the University of Chicago. She holds a PhD in physics from the International School of Advanced Studies (SISSA) in Trieste, Italy. She was the head of the Quantum Simulations Group at the Lawrence Livermore National Laboratory and Professor of Chemistry and Physics at the University of California, Davis, prior to joining the University of Chicago. She is a Fellow of the American Physical Society (APS) and of the American Academy of Arts and Sciences (AAAS). She received an award of excellence from the Department of Energy (2000) and the Science and Technology Award from the Lawrence Livermore National Laboratory (2004). She served as chair of the Division of Computational Physics of the American Physical Society (2006-2007) and of the Extreme Physics and Chemistry of Carbon Directorate of the Deep Carbon Observatory (2010-2013). Her research activity is focused on quantum simulations of systems and processes relevant to condensed matter physics, physical chemistry, molecular engineering and nano-science.

Tuesday, June 2, 2015
HG F30, 18:30 - 19:20

IP4 Computational Challenges in Macroeconomics, Thomas Sargent (New York University, USA)

Chair: Felix Kübler (University of Zurich, Switzerland)

Abstract
Modern macroeconomic theory has provided many qualitative insights into the functioning of financial and labor markets in our complex modern economies. But determining the quantitative importance of frequently countervailing forces requires much more than the pencil and paper methods used by economic theorists. My talk will describe some new economic ideas brought by economic theory and how efforts to develop computational tools promise to help macroeconomists perform quantitative analyses that can inform policy choices.

Biography
Thomas J. Sargent is the W. R. Berkley Professor at New York University, a joint appointment in the Economics Department and the Stern School of Business. He has been a Senior Fellow at the Hoover Institution since 1987. He was awarded the 2011 Nobel Prize in Economics for his empirical research on cause and effect in the macroeconomy. Professor Sargent earned his BA from the University of California, Berkeley in 1964, and his PhD in economics from Harvard University in 1968. He has held Professor appointments at the University of Minnesota, University of Chicago, and Stanford University. Sargent was elected a fellow of the National Academy of Sciences in 1983.

Wednesday, June 3, 2015
HG F30, 09:00 - 10:00

IP5 Towards Exascale Simulation of Turbulent Combustion, Jacqueline Chen (Sandia National Laboratories, USA)

Chair: Gretar Tryggvason (University of Notre Dame, USA)

Abstract
Exascale computing will enable combustion simulations in parameter regimes relevant to next-generation combustors burning alternative fuels. The first principles direct numerical simulations (DNS) are needed to provide the underlying science base required to develop vastly more accurate predictive combustion models used ultimately to design fuel efficient, clean burning vehicles, planes, and power plants for electricity generation. However, making the transition to exascale poses a number of algorithmic, software and technological challenges. As Moore's Law and Dennard scaling come to an end exascale computing will be achieved only through massive concurrency. Addressing issues of data movement, power consumption, memory capacity, interconnection bandwidth, programmability, and scaling through combustion co-design are critical to ensure that future combustion simulations can take advantage of emerging computer architectures. Co-design refers to a computer system design process where combustion science requirements influence architecture design and constraints inform the formulation and design of algorithms and software. The current state of petascale DNS of turbulent combustion will be reviewed followed by a discussion of current combustion exascale combustion co-design topics: 1) architectural modeling and simulation of the behavior of combustion applications on future extreme architectures; and 2) programming model and runtime for heterogeneous, hierarchical machines with inherent variability. While bulk synchronous programming and data parallelism have been operative at the petascale, the movement to exascale requires a shift towards asynchronous programming, where to extract maximum parallelism, both data and task parallelism accessing disjoint sets of fields is required. An example from a recent refactorization of a combustion DNS code, S3D, using an asynchronous model, Legion, with dynamic runtime analysis at scale will be presented.

Biography
Jacqueline H. Chen is a Distinguished Member of Technical Staff at the Combustion Research Facility at Sandia National Laboratories. She has contributed broadly to research in petascale direct numerical simulations (DNS) of turbulent combustion focusing on fundamental turbulence-chemistry interactions. In collaboration with computer scientists and applied mathematicians she is the founding Director of the Center for Exascale Simulation of Combustion in Turbulence (ExaCT). She received several DOE INCITE Awards in the last few years and the Asian American Engineer of the Year Award in 2009.

Wednesday, June 3, 2015
HG F30, 12:00 - 12:50

IP6 Algorithmic Adaptations to Extreme Scale, David Keyes (King Abdullah University of Science and Technology, Saudi Arabia)

Chair: Olaf Schenk (Università della Svizzera italiana, Switzerland)

Abstract
Algorithmic adaptations are required to use anticipated exascale hardware near its potential, since the code base has been engineered to squeeze out flops. Instead, algorithms must now squeeze out synchronizations, memory, and transfers, while extra flops on locally cacheable data represent small costs in time and energy. Today's scalable solvers, in particular, exploit frequent global synchronizations. After decades of programming model stability with bulk synchronous processing (BSP), new programming models and new algorithmic capabilities (to take advantage, e.g., of forays in data assimilation, inverse problems, and uncertainty quantification) must be co-designed with the hardware. We briefly recap the architectural constraints, highlight some work at KAUST, and outline future directions.

Biography
David Keyes is Director of the Extreme Computing Research Center at KAUST. He earned a BSE in aerospace and mechanical sciences from Princeton in 1978 and PhD in applied mathematics from Harvard in 1984. Keyes works at the interface between parallel computing and the numerical analysis of PDEs, with a focus on scalable implicit solvers. Newton-Krylov-Schwarz (NKS), Additive Schwarz Preconditioned Inexact Newton (ASPIN), and Algebraic Fast Multipole (AFM) methods are methods he helped name and popularize. Before joining KAUST as a founding dean in 2009, he led scalable solver software projects in the ASCI and SciDAC programs of the US Department of Energy, ran university collaboration programs at NASA's ICASE and the LLNL's ISCR, and taught at Columbia, Old Dominion, and Yale Universities. He is a Fellow of SIAM and AMS.