A5039319913- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Machine Learning in Materials Science
- Quantum Chromodynamics and Particle Interactions
- Superconducting Materials and Applications
- Parallel Computing and Optimization Techniques
- Nuclear Physics and Applications
- Distributed and Parallel Computing Systems
- Particle physics theoretical and experimental studies
- Particle accelerators and beam dynamics
- X-ray Diffraction in Crystallography
- High-Energy Particle Collisions Research
- Advanced Materials Characterization Techniques
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Minerals Flotation and Separation Techniques
- Advanced Data Storage Technologies
- Simulation Techniques and Applications
- Nuclear reactor physics and engineering
- High-Velocity Impact and Material Behavior
- Solidification and crystal growth phenomena
- Electromagnetic Scattering and Analysis
- Cloud Computing and Resource Management
- Traffic Prediction and Management Techniques
- Vehicular Ad Hoc Networks (VANETs)
Oak Ridge National Laboratory
2014-2024
Pacific Northwest National Laboratory
2021
Conference Board
2013
Iowa State University
2004-2007
New Mexico State University
2000-2002
An effective latency-hiding mechanism is presented in the parallelization of agent-based model simulations (ABMS) with millions agents. The designed to accommodate hierarchical organization as well heterogeneity current state-of-the-art parallel computing platforms. We use
In complex phenomena such as epidemiological outbreaks, the intensity of inherent feedback effects and significant role transients in dynamics make simulation only effective method for proactive, reactive or post facto analysis. The spatial scale, runtime speed, behavioral detail needed detailed simulations epidemic outbreaks cannot be supported by sequential small-scale parallel execution, making it necessary to use large-scale processing. Here, an optimistic execution a new discrete event...
The development of the multilevel fast multipole algorithm (MLFMA) and its multiscale variants have enabled use integral equation (IE) based solvers to compute scattering from complicated structures. Development scalable parallel algorithms, extend reach these solvers, has been a topic intense research for about decade. In this paper, we present new implementation IE solver that is augmented with wideband MLFMA on large number processors. employed here, handle problems, hybrid combination...
The dynamics of RE (runaway electrons) in fusion plasmas span a wide range temporal scales, from the fast gyro-motion, ∼10−11 s, to observational time ∼10−2→1 s. To cope with this scale separation, are usually studied within bounce-average or guiding center approximations. Although these approximations have yielded valuable insights, study predictive capabilities calls for incorporation full orbit effects configuration space presence three-dimensional magnetic fields. We present numerical...
Calculations of the plasma response to applied non-axisymmetric fields in several DIII-D discharges show that predicted displacements depend strongly on edge current density. This result is found using both a linear two-fluid-MHD model (M3D-C1) and nonlinear ideal-MHD (VMEC). Furthermore, it observed probability discharge being localized mode (ELM)-suppressed most closely related density, as opposed pressure gradient. It with stronger kink are closer peeling–ballooning stability limit ELITE...
This paper presents the first fully 3-dimensional (3D) equilibrium reconstruction of a helical core in tokamak device. Using new parallel implementation Variational Moments Equilibrium Code (PARVMEC) coupled to V3FIT, 3D reconstructions can be performed at resolutions necessary produce states nominally axisymmetric equilibria. In flux pumping experiment on DIII-D, an external n = 1 field was applied while 3/2 neoclassical tearing mode suppressed using ECCD. The externally rotated past set...
Understanding structural properties of materials and how they relate to its atomic structure, while extremely challenging, is a key scientific quest that has dominated the landscape research for decades. Neutron X-ray scattering state-of-the-art method investigate material structure on scale. Traditional methods processing neutron data decipher target have relied computing patterns using physics-based forward models comparing them with experimentally gathered profiles within computationally...
A methodology and its associated algorithms are presented for mapping a novel, field-based vehicular mobility model onto graphical processing unit computational platform simulating in large-scale road networks. Of particular focus is the achievement of real-time execution, on desktop platforms, networks comprised millions nodes links, multi-million counts simultaneously active vehicles. The realized system called GARFIELD, whose implementation details performance study described. runtime...
The spatial scale, runtime speed and behavioral detail of epidemic outbreak simulations together require the use large-scale parallel processing. In this paper, an optimistic discrete event execution a reaction-diffusion simulation model outbreaks is presented, with implementation over ¿sik simulator. Rollback support achieved development novel reversible that combines reverse computation small amount incremental state saving. Parallel speedup other performance metrics are tested on...
Recent experimental observations have found turbulent fluctuation structures that are non-axisymmetric in a tokamak with applied 3D fields. In this paper, two fluid resistive effects shown to produce changes relevant transport the modeled magnetohydrodynamic (MHD) equilibrium of pedestals these fields applied. Ideal MHD models insufficient reproduce effects. By calculating ideal using VMEC code, geometric shaping parameters determine linear turbulence stability, including normal curvature...
Rapid growth in data, computational methods, and computing power is driving a remarkable revolution what variously termed machine learning (ML), statistical learning, artificial intelligence. In addition to highly visible successes machine-based natural language translation, playing the game Go, self-driving cars, these new technologies also have profound implications for experimental science engineering, as well exascale systems that Department of Energy (DOE) developing support those...
Spacefilling curves (SFCs) are widely used for parallel domain decomposition in scientific computing applications. The proximity preserving properties of SFCs expected to keep most accesses local applications that require efficient access spatial neighborhoods. While experimental results confirm this behavior, a rigorous mathematical analysis turns out be rather hard and rarely attempted. In paper, we analyze SFC based uniform random distribution three dimensions. Let n denote the number...
Radio signal strength estimation is essential in many applications, including the design of military radio communications and industrial wireless installations. For scenarios with large or richly featured geographical volumes, parallel processing required to meet memory computation time demands. Here, we present a scalable efficient execution sequential model for propagation recently developed by Nutaro et al. [2008]. Starting that model, (a) provide vector-based reformulation has...
Large, spontaneous m/n = 1/1 helical cores are shown to be expected in tokamaks such as ITER with extended regions of low- or reversed- magnetic shear profiles and q near 1 the core. The threshold for this symmetry breaking is determined using VMEC scans, beginning reconstructed 3D equilibria from DIII-D Alcator C-Mod based on observed internal deformations. core a saturated kink mode (Wesson 1986 Plasma Phys. Control. Fusion 28 243); its onset proportional around 1. Below threshold, applied...
We present results from a study of light meson spectra and structure obtained within the framework light-front QCD formulated on transverse lattice. discuss how imposing Lorentz covariance conditions dispersion relations allows determination parameters in lattice Hamiltonian. The pion distribution amplitude this is rather close to its asymptotic shape.
Abstract A technique for tokamak equilibrium reconstructions is used multiple DIII-D discharges, including L-mode and H-mode cases when weakly 3D fields <?CDATA $\left(\delta B/B\sim {{10}^{-3}}\right)$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mo stretchy="false">(</mml:mo> <mml:mi>δ</mml:mi> <mml:mi>B</mml:mi> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mo>∼</mml:mo> <mml:msup> <mml:mn>10</mml:mn>...
The ability to sustain magnetically confined plasma in a state of stable equilibrium is crucial for optimal and cost-effective operations fusion devices like tokamaks stellarators. Variational Moments Equilibrium Code (VMEC) the de-facto serial application used by scientists compute magnetohydrodynamics (MHD) equilibria study physics three dimensional plasmas configurations. Modern energy experiments have larger system scales with more interactive experimental workflows, both demanding...
In large-scale scenarios, transportation modeling and simulation is severely constrained by time. For example, few real-time simulators scale to evacuation traffic scenarios at the level of an entire state, such as Louisiana (approximately 1 million links) or Florida (2.5 links). New approaches are needed overcome severe computational demands conventional (microscopic mesoscopic) techniques. Here, a new execution methodology explored that holds potential provide tradeoff among behavioral...
Fast, accurate three dimensional reconstructions of plasma equilibria, crucial for physics interpretation fusion data generated within confinement devices like stellarators/ tokamaks, are computationally very expensive and routinely require days, even weeks, to complete using serial approaches. Here, we present a parallel implementation the reconstruction code, V3FIT. A formal analysis identify performance bottlenecks scalability limits this new implementation, which combines both task...
Large, spontaneous m/n = 1/1 helical cores are predicted in tokamaks with extended regions of low- or reversed-magnetic shear profiles a region within the q 1 surface and an onset condition determined by constant (dp/dρ)/Bt2 along threshold. These 3D modes occurred frequently Alcator C-Mod during ramp-up when slow current penetration results reversed q-profile. The early development core were simulated using new time-dependent equilibrium reconstruction, based on ideal MHD code VMEC....
We present results from a study of meson spectra and structure in the limit where one quark is infinitely heavy. The calculations, based on framework light-front QCD formulated transverse lattice, are first non-perturbative studies B mesons QCD. calculate Isgur-Wise form factor, light-cone distribution amplitude, heavy-quark parton function leptonic decay constant mesons.