Berkeley Lab Staff Make Key Contributions to National Lab Science Day on Capitol Hill
Forty staff members from across the DOE national lab complex helped convey the labs’ contributions and achievements to Congressional members and staff during National Lab Science Day. The education and outreach event, organized by the DOE Office of Congressional and Intergovernmental Affairs to highlight the national laboratory system as a cornerstone of the U.S. innovation ecosystem, was held Wednesday, April 20, in the Dirksen Senate Office Building on Capitol Hill in Washington, D.C.
Jon Bashor, communications manager for Computing Sciences, coordinated the Science and Computation display, recruiting staff from Argonne, Oak Ridge, Lawrence Livermore and SLAC to show how supercomputers are integral to scientific discovery, national security and economic competitiveness. Lauren Rotman, leader of ESnet’s Science Engagement Team, demonstrated how ESnet runs a dedicated science network linking the national labs and collaborators around the world. An interactive video display allowed visitors to watch short simulations showing how researchers use supercomputers to answer challenging questions of national importance.
2D 'Flat' Boron Yields a Superconducting Surprise
Density functional theory simulations run at NERSC helped Rice University researchers determine that two-dimensional boron is a natural low-temperature superconductor. In fact, it may be the only two-dimensional (2D) material with such potential.
Rice theoretical physicist Boris Yakobson and his co-workers published their calculations last month in Nano Letters. Their work reveals that atomically flat boron is metallic and will transmit electrons with no resistance. The hitch is that it loses its resistivity only when very cold, in this case between 10 and 20 kelvins (roughly, minus-430 degrees Fahrenheit). But for making very small superconducting circuits, it might be the only game in town.
Berkeley Lab Hosts Fourth X-Stack PI Meeting
Berkeley Lab hosted the fourth annual X-Stack PI meeting April 6 and 7, where X-Stack researchers, the facilities teams, application scientists and developers from national laboratories, universities and industry met to share the latest developments in X-Stack application codes and identify further modifications.
X-Stack was launched in 2012 by the U.S. Department of Energy’s Advanced Scientific Computing Research program to support the development of exascale software tools, including programming languages and libraries, compilers and runtime systems, that will help programmers handle massive parallelism, data movement, heterogeneity and failures as the scientific community transitions to the next generation of extreme-scale supercomputers. A total of nine X-Stack programs were designated to develop complete solutions that address multiple components of the system software stack: DEGAS, D-TEC, XPRESS, Traleika, DynAX, XTUNE, GVR, CORVETTE and SLEEC.
De Jong's Actinide Research Featured by ORNL
The actinide research of CRD's Bert de Jong was recently featured on Oak Ridge National Laboratory's web site. Actinides are highly radioactive elements that were the legacy of nuclear research done in the 1940s and 50s. At that time, scientists didn't fully understand the risks of long-term handling and storage of radioactive waste, so there are still radioactive materials from the Manhattan Project in storage awaiting processing and final disposition. One of the major clean-up challenges lies in separating radioactive compounds from their more inert counterparts for safe removal and storage.
To this end, a multi-institution team has been doing research to understand actinide chemistry at the molecular level in hopes of designing methods to clean up contamination and safely store spent nuclear fuel.
De Jong’s group works with teams at both Berkeley Lab and the University of Utah to understand how to change and control an element’s oxidation state—or how many electrons an atom can shed or add to change its charge.
By altering the behavior of elements like uranium—or its actinide relatives, thorium, neptunium, and plutonium—incorporating them in molecules and forming chemical bonds, researchers hope to extract radioactive elements from the environment or waste storage tanks and keep them in a more innocuous form, or to separate them for reuse as nuclear fuel.
This Week's CS Seminars
Wednesday, April 27
Twitter Heron @ Scale
10:30 to 11:30 a.m., Wang Hall - Bldg. 59, Room 4102
Karthik Ramasamy, Twitter
Twitter generates billions and billions of events per day. Analyzing these events in real time presents a massive challenge. Twitter designed and deployed a new streaming system called Heron. Heron has been in production nearly 2 years and is widely used by several teams for diverse use cases. In this talk, we will share our operating experiences and challenges of running Heron at scale and the approaches that we took to solve those challenges.
CITRIS Research Exchange
Entrepreneurship and Climate Change
12 to 1 p.m., 310 Sutardja Dai Hall, Banato Auditorium, UC Berkeley
Sue Carter, UC Santa Cruz
Sue Carter earned her Ph.D. from the University of Chicago and worked at AT&T Bell Laboratories as a postdoctoral fellow and IBM Almaden Research Center as a visiting researcher before joining the faculty at UC Santa Cruz in 1995, where she also serves as the Associate Dean of Graduate Studies. Her research focuses on thin film optoelectronic devices and technologies for sustainability. She is currently the UCSC Faculty Climate Action Champion and the Director for the Center for Innovation and Entrepreneurial Development (CIED) at UCSC, for which she recently received an Award for Outstanding Faculty Leadership in Presidential Initiatives. She serves on both the UCOP Applied Research Working Group for the Carbon Neutrality Initiative and on the UCOP Group for the Innovation & Entrepreneurship Initiative. She is also a Fellow of the American Physical Society and has also been the Chair of the APS Group for Energy Research.
She has also been actively involved with entrepreneurship, launching three start-up companies ranging from photovoltaic technologies to K-12 science education.
Positivity-preserving High Order Discontinuous Galerkin Schemes for Compressible Navier-Stokes Equations
3:30 to 4:30 p.m., 939 Evans Hall, UC Berkeley
Xiangxiong Zhang, Purdue University
For gas dynamics equations such as compressible Euler and Navier-Stokes equations, preserving the positivity of density and pressure without losing conservation is crucial to stabilize the numerical computation. The L1-stability of mass and energy can be achieved by enforcing the positivity of density and pressure during the time evolution. However, high order schemes such as DG methods do not preserve the positivity. It is difficult to enforce the positivity without destroying the high order accuracy and the local conservation in an efficient manner for time-dependent gas dynamics equations. For compressible Euler equations, a weak positivity property holds for any high order finite volume type schemes including DG methods, which was used to design a simple positivity-preserving limiter for high order DG schemes in Zhang and Shu, JCP 2010. Generalizations to compressible Navier-Stokes equations are however nontrivial. We show that weak positivity property still holds for DG method solving compressible Navier-Stokes equations if a proper penalty term is added in the scheme. This allows us to obtain the first high order positivity-preserving schemes for compressible Navier-Stokes equations.
Link of the Week: Is Our Universe an Elaborate Simulation?
Philosophers have spent centuries asking how we know that reality is, well, real. The 17th Century French philosopher Rene Descartes summed up his thoughts on the subject with "I think, therefore I am." But in an age of virtual reality, that may not be enough. Astronomer Neil DeGrasse Tyson last week posited that the entire universe we see around us may be nothing more than an elaborate simulation. This theory has been debated by astronomers and astrophysicists for decades, but speaking at the Issac Asimov Memorial Debate held at the Hayden Planetarium (which he directs) DeGrasse Tyson declared the concept is extremely likely to be true.