A5027682055- Advanced Data Storage Technologies
- Gamma-ray bursts and supernovae
- Distributed and Parallel Computing Systems
- Parallel Computing and Optimization Techniques
- Astro and Planetary Science
- GNSS positioning and interference
- Astronomical Observations and Instrumentation
- Cloud Computing and Resource Management
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Spacecraft and Cryogenic Technologies
- Galaxies: Formation, Evolution, Phenomena
- Security and Verification in Computing
- Computational Fluid Dynamics and Aerodynamics
- Computational Physics and Python Applications
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Simulation Techniques and Applications
- Meteorological Phenomena and Simulations
- Stellar, planetary, and galactic studies
- Atmospheric and Environmental Gas Dynamics
- Radio, Podcasts, and Digital Media
- Particle Detector Development and Performance
- Seismology and Earthquake Studies
- Scientific Research and Discoveries
National Energy Research Scientific Computing Center
2017-2021
Lawrence Berkeley National Laboratory
2016-2020
University of Oklahoma
2012-2017
AMReX is a C++ software framework that supports the development of block-structured adaptive mesh refinement (AMR) algorithms for solving systems partial differential equations (PDEs) with complex boundary conditions on current and emerging architectures.
The nearby Type Ia supernova (SN Ia) SN 2011fe in M101 (cz = 241 km s−1) provides a unique opportunity to study the early evolution of "normal" Ia, its compositional structure, and elusive progenitor system. We present 18 high signal-to-noise spectra during first month beginning 1.2 days post-explosion with an average cadence 1.8 days. This gives clear picture how various line-forming species are distributed within outer layers ejecta, including that unburned material (C+O). follow C ii...
System and node architectures continue to diversify better balance on-node computation, memory capacity, bandwidth, interconnect power, cost for specific computational workloads. For many application developers, achieving performance portability (effectively exploiting the capabilities of multiple architectures) is a desired goal. Unfortunately, dramatically different per-node coupled with differences in machine can lead developers being unable determine whether they have attained or simply...
Modern cosmological simulations have reached the trillion-element scale, rendering data storage and subsequent analysis formidable tasks. To address this circumstance, we present a new MPI-parallel approach for of simulation while runs, as an alternative to traditional workflow consisting periodically saving large sets disk 'offline' analysis. We demonstrate in compressible gasdynamics/N-body code Nyx, hybrid MPI+OpenMP based on BoxLib framework, used large-scale simulations. enabled...
We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed four normal Type Ia supernovae ranging from day +56.5 +85. This is the epoch during which are believed be undergoing transition photospheric phase, where characterized by line scattering above an optically thick photosphere, nebular consist thin emission forbidden lines. find that most spectral features in can accounted for permitted lines Fe ii Co ii. In addition, we [Ni ii]...
NERSC has partnered with 20 representative application teams to evaluate performance on the Xeon-Phi Knights Landing architecture and develop an application-optimization strategy for greater workload recently installed Cori system. In this article, we present early case studies summarized results from a subset of applications highlighting impact important differences between traditional Xeon processors. We summarize status describe optimization that formed.
We describe the AMReX suite of astrophysics codes and their application to modeling problems in stellar astrophysics. Maestro is tuned efficiently model subsonic convective flows while Castro models highly compressible associated with explosions. Both are built on block-structured adaptive mesh refinement library AMReX. Together, these enable a thorough investigation phenomena, including Type Ia supernovae X-ray bursts. science applications approach we taking make performant current future...
NERSC has partnered with 20 representative application teams to evaluate performance on the Xeon-Phi Knights Landing architecture and develop an application-optimization strategy for greater workload recently installed Cori system. In this article, we present early case studies summarized results from a subset of applications highlighting impact important differences between traditional Xeon processors. We summarize status describe optimization that formed.
SN 2012dn is a super-Chandrasekhar mass candidate in purportedly normal spiral (SAcd) galaxy, and poses challenge for theories of type Ia supernova diversity. Here we utilize the fast highly parameterized spectrum synthesis tool, SYNAPPS, to estimate relative expansion velocities species inferred from optical spectra obtained with six facilities. As previous studies Ia, find that both unburned carbon intermediate elements are spatially coincident within ejecta near below 14,000 km/s....
Summary The newest NERSC supercomputer Cori is a Cray XC40 system consisting of 2,388 Intel Xeon Haswell nodes and 9,688 Xeon‐Phi “Knights Landing” (KNL) nodes. Compared to the Xeon‐based clusters users are familiar with, optimal performance on requires consideration KNL mode settings; process, thread, memory affinity; fine‐grain parallelization; vectorization; use high‐bandwidth MCDRAM memory. This paper describes our efforts preparing for through Exascale Science Application Program, Web...
Nyx is a highly parallel, adaptive mesh, finite-volume N-body compressible hydrodynamics solver for cosmological simulations.It has been used to simulate different scenarios with recent focus on the intergalactic medium and Lyman alpha forest.Together, Nyx, astrophysical simulation code, Castro (Almgren et al., 2010), low Mach number code MAESTROeX (Fan 2019), make up AMReX-Astrophysics Suite of open-source, performance-portable codes.
We examine the scalability and performance of an open-source, coarray Fortran (CAF) mini-application (mini-app) that implements parallel, numerical algorithms dominate execution The Intermediate Complexity Atmospheric Research (ICAR) [4] model developed at National Center for (NCAR). 2008 mini-app includes one implementation a collective subroutine defined in Committee Draft upcoming 2018 standard. ability CAF to run atop various communication layers increasing compiler availability...
We use observed UV through near IR spectra to examine whether SN 2011fe can be understood in the framework of Branch-normal SNe Ia and its individual peculiarities. As a benchmark, we delayed-detonation model with progenitor metallicity Z_solar/20. study sensitivity features variations metallicity, outer density profile, distribution radioactive nickel. The effect have relatively small on synthetic spectra. also find that abundance stratification resembles closely delayed detonation...
The nature of dark energy and the complete theory gravity are two central questions currently facing cosmology. A vital tool for addressing them is 3-point correlation function (3PCF), which probes deviations from a spatially random distribution galaxies. However, 3PCF's formidable computational expense has prevented its application to astronomical surveys comprising millions billions We present Galactos, high-performance implementation novel, O(N2) algorithm that uses load-balanced k-d tree...
We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349 and 578 d post-maximum light, as well an ultraviolet (UV) spectrum obtained with Hubble Space Telescope 360 light. compare these observations synthetic produced radiative transfer code phoenix. The day +100 can be fitted models that neglect collisional data for forbidden lines. Curiously, including recomputing fit yields a quite similar spectrum, but different combinations lines forming some stronger...
In recent years there has been increasing use of HPC facilities for HEP experiments. This initially focussed on less I/O intensive workloads such as generator-level or detector simulation. We now demonstrate the efficient running I/O-heavy analysis at NERSC, ATLAS and ALICE LHC collaborations well astronomical image DESI BOSS.
When acquiring a supercomputer it is desirable to specify its performance using single number. For many procurements, this usually stated as increase over current generation platform, for example machine A provides 10 times greater than B. The determination of such number not necessarily simple process; there no universal agreement on how calculation performed and each facility uses their own method. In the future, landscape will be further complicated because systems contain heterogeneous...
In supernova spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following photosphere's recession. Most treatments and analyses post-photospheric optical spectra supernovae assume that forbidden-line emission comprises most if not all features. However, evidence exists which suggests some exhibit line profiles formed via resonance-scattering even months or years after explosion. To explore this possibility we present a...