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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade
Generating Derivative Structures From Multilattices: Algorithm And Application To Hcp Alloys, Gus L. W. Hart, Rodney W. Forcade
Faculty Publications
We present an algorithm for generating all derivative superstructures of a nonprimitive parent lattice. The algorithm has immediate application in important materials design problems such as modeling hexagonal-close-packed (hcp) alloys. Extending the work of Hart and Forcade [Phys. Rev. B 77, 224115 (2008)] (which applies only to Bravais lattices), this approach applies to arbitrary multilattices. The algorithm enumerates superlattices and atomic configurations using permutation groups rather than direct geometric comparisons. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The algorithm is very efficient; the run time scales linearly with …
Algorithm For Generating Derivative Structures, Gus L. W. Hart, Rodney W. Forcade
Algorithm For Generating Derivative Structures, Gus L. W. Hart, Rodney W. Forcade
Faculty Publications
We present an algorithm for generating all derivative superstructures--for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The run time of the algorithm scales linearly with the number of unique structures found.
Algorithm Refinement For Fluctuating Hydrodynamics, Alejandro Garcia, S. Williams, J. B. Bell
Algorithm Refinement For Fluctuating Hydrodynamics, Alejandro Garcia, S. Williams, J. B. Bell
Faculty Publications
This paper introduces an adaptive mesh and algorithm refinement method for fluctuating hydrodynamics. This particle-continuum hybrid simulates the dynamics of a compressible fluid with thermal fluctuations. The particle algorithm is direct simulation Monte Carlo (DSMC), a molecular-level scheme based on the Boltzmann equation. The continuum algorithm is based on the Landau–Lifshitz Navier–Stokes (LLNS) equations, which incorporate thermal fluctuations into macroscopic hydrodynamics by using stochastic fluxes. It uses a recently developed solver for the LLNS equations based on third-order Runge–Kutta. We present numerical tests of systems in and out of equilibrium, including time-dependent systems, and demonstrate dynamic adaptive refinement by the …
An Improved Distance Heuristic Function For Directed Software Model Checking, Eric G. Mercer, Neha Rungta
An Improved Distance Heuristic Function For Directed Software Model Checking, Eric G. Mercer, Neha Rungta
Faculty Publications
State exploration in directed software model checking is guided using a heuristic function to move states near errors to the front of the search queue. Distance heuristic functions rank states based on the number of transitions needed to move the current program state into an error location. Lack of calling context information causes the heuristic function to underestimate the true distance to the error; however, inlining functions at call sites in the control flow graph to capture calling context leads to an exponential growth in the computation. This paper presents a new algorithm that implicitly inlines functions at call sites …
Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura
Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura
Faculty Publications
Image interpolation algorithms try to fit a function to a matrix of samples in a "natural-looking" way. This paper presents edge inference, an algorithm that does this by mixing neural network regression with standard image interpolation techniques. Results on gray level images are presented, and it is demonstrated that edge inference is capable of producing sharp, natural-looking results. A technique for reintroducing noise is given, and it is shown that, with noise added using a bicubic interpolant, edge inference can be regarded as a generalization of bicubic interpolation. Extension into RGB color space and additional applications of the algorithm are …
Prioritized Soft Constraint Satisfaction: A Qualitative Method For Dynamic Transport Selection In Heterogeneous Wireless Environments, Heidi R. Duffin, Michael A. Goodrich, Charles D. Knutson
Prioritized Soft Constraint Satisfaction: A Qualitative Method For Dynamic Transport Selection In Heterogeneous Wireless Environments, Heidi R. Duffin, Michael A. Goodrich, Charles D. Knutson
Faculty Publications
This paper presents Prioritized Soft Constraint Satisfaction (PSCS), a novel approach to selecting the “best” transport in dynamic wireless transport switching systems. PSCS maintains a satisfying connection to another endpoint by choosing transports based on a user-established range of preferences and priority for criteria such as speed, power, range and cost. Additionally, feedback is provided regarding tradeoffs among the criteria, thus enabling the user to adjust inputs according to the capabilities of the system. We also recommend guidelines for setting preferences and priorities.
A Consistent Boltzmann Algorithm, Alejandro Garcia, F. Alexander, B. Alder
A Consistent Boltzmann Algorithm, Alejandro Garcia, F. Alexander, B. Alder
Faculty Publications
The direct simulation Monte Carlo method for the Boltzmann equation is modified by an additional displacement in the advection process and an enhanced collision rate in order to obtain the exact hard sphere equation of state at all densities. This leads to consistent thermodynamic and transport properties in the low density (Boltzmann) regime. At higher densities transport properties are comparable to the predictions of the Enskog model. The algorithm is faster than molecular dynamics at low and moderate densities and readily run on a parallel architecture