A5035190674- Ionosphere and magnetosphere dynamics
- Magnetic confinement fusion research
- Electromagnetic Simulation and Numerical Methods
- Solar and Space Plasma Dynamics
- Plasma Diagnostics and Applications
- Electromagnetic Scattering and Analysis
- Computational Geometry and Mesh Generation
- Computer Graphics and Visualization Techniques
- Distributed and Parallel Computing Systems
- Scientific Computing and Data Management
- Advanced Numerical Methods in Computational Mathematics
- Particle accelerators and beam dynamics
- Simulation Techniques and Applications
- Computational Fluid Dynamics and Aerodynamics
- Infrastructure Resilience and Vulnerability Analysis
- Quantum Computing Algorithms and Architecture
- Underwater Acoustics Research
- Oceanographic and Atmospheric Processes
- Methane Hydrates and Related Phenomena
- Meteorological Phenomena and Simulations
- Laser-Plasma Interactions and Diagnostics
- Quantum Information and Cryptography
- Computability, Logic, AI Algorithms
- Algorithms and Data Compression
- Terrorism, Counterterrorism, and Political Violence
Los Alamos National Laboratory
2009-2023
Los Alamos Medical Center
2011
Research Applications Corporation (United States)
2010
Lawrence Livermore National Laboratory
1990-2008
United States Naval Research Laboratory
1994
George Washington University
1994
University of Delaware
1984
William & Mary
1979-1981
University of Alaska Fairbanks
1981
Williams (United States)
1981
As quantum computers become available to the general public, need has arisen train a cohort of programmers, many whom have been developing classical computer programs for most their careers. While currently less than 100 qubits, computing hardware is widely expected grow in terms qubit count, quality, and connectivity. This review aims explain principles programming, which are quite different from with straightforward algebra that makes understanding underlying fascinating mechanical...
The induced electric field produced by magnetohydrodynamic processes can accelerate test particles very efficiently under certain circumstances. Numerical experiments indicate that are accelerated to high energy the fields accompanying reconnection is triggered finite amplitude turbulent fluctuations. This neutral point mechanism includes both coherent and stochastic components of acceleration. Turbulence appears influence acceleration in two ways: It enhances while producing a gives rise...
Test-particle acceleration is studied in a two-dimensional, turbulent magnetohydrodynamic simulation whose initial magnetic field configuration periodic sheet pinch. Some test particles become trapped near large electric the reconnnection region for approximately an Alfv\'en transit time. The maximum speed attained consistent with analytic estimate which depends on reconnection field, speed, and ratio of Larmor period to
A possible source of free energy available for accelerating charged particles is conversion magnetic to particle in reconnecting fields. Recent simulations using test suggests that reconnection may efficiently accelerate the maximum energies are observed several astrophysical contexts. simple analytic formula used conjunction with simulation results predict achievable a particular plasma environment result solar flares capable GeV. In magnetospheric substorms predicted can reach hundred keV,...
A two‐dimensional magnetoinductive particle‐in‐cell code is used to compare the stability of isotropic and anisotropic current layers in a collisionless plasma. We find, agreement with recent theories, that temperature anisotropy T ⊥ > ∥ significantly enhances instability. The simulation growth rates agree well analytical predictions linear phase. Nonlinear are larger than apparently result coalescence For fixed system length influence on increases anisotropy. This evidently because shift...
The nonlinear progressive wave equation (NPE) is used to investigate propagation of acoustic pulses in a shallow ocean waveguide. nonlinearity shown affect transmission and reflection at fluid–fluid interface. It that one effect the reduce critical angle for total internal from linear case. When loss versus range simple isovelocity waveguide compared with normal mode parabolic calculations, result shows increased as long amplitude significant (an expected shock processes), bottom...
A one-dimensional electromagnetic particle-in-cell (PIC) model is used to investigate the Alfvén ion-cyclotron (AIC) instability in high-β plasmas with large ion temperature anisotropies. The simulation results are compared linear and quasilinear theory. Nonlinear effects, such as rate at which anisotropy relaxes level of perturbed magnetic wave energy saturation, a function β initial anisotropy. It found that for β⊥ (β⊥>3) decays residual time comparable an period. Simulations...
A comparison is made between two classes of Vlasov equilibria with respect to the ion tearing mode instability. The first class that a current sheet in equilibrium vacuum (Harris type). second magnetized background plasma. via simple magnetoinductive simulation involving ions alone. We find presence species has several dramatic effects: linear growth rates are affected, can be stabilized or destabilized by plasma, and exchange energy particles fields affected. In particular, saturation wave...
Scientific research communities can be represented as heterogeneous or multidimensional networks encompassing multiple types of entities and relationships. These might include researchers, institutions, meetings, publications, connected by relationships like authorship, employment, attendance. We describe a method for efficiently flexibly capturing, storing, extracting information from scientific using graph database. The database structure is based on an ontology that captures allowable...
The statistical theory of Montgomery, Turner, and Vahala, which determines the most probable ideal magnetohydrodynamic equilibrium compatible with given information on only a few global parameters (e.g., energy E, magnetic helicity H, flux Φ, current I, ⋅⋅⋅) is extended investigated for both tokamak regime (in experimentally Φ≫μ0aI, being plasma radius) reversed field pinch (Φ≪μ0aI). One obtains typical relevant profiles in appropriate regimes. Most equilibria sequences are as...
Decisions regarding infrastructure resilience are made under uncertainty and involve trade-offs among competing objectives. An effective way of understanding how uncertainties propagate multiple objectives is to use a computer simulation that integrates high-level representations each infrastructure, their interdependencies, reactions variety potential disruptions. To address this need for such decision support tool, paper considers multidisciplinary federation systems dynamics models the...
As part of a long range plan to develop comprehensive climate systems modeling capability, the authors have taken atmospheric general circulation model originally developed by Arakawa and collaborators at UCLA recast it in portable, parallel form. The code uses an explicit time-advance procedure on staggered three-dimensional Eulerian mesh. They implemented two-dimensional latitude/longitude domain decomposition message passing strategy. Both dynamic memory management interprocess...
Many chemical systems of interest consist sets reactions that contain iterated sequences elongate a molecular chain. For example, such are commonly found in the transcription DNA or translation RNA. However, there competitive can prematurely terminate chain-elongation process. A hidden Markov method appropriate for modeling chains with processes (i.e., premature chain termination) is developed. The an extension model suggested by Gibson and Bruck (J. Phys. Chem. 2000, 104, 1876). equivalence...