Lev Barash - Academia.edu (original) (raw)

Papers by Lev Barash

Research paper thumbnail of GPU-Accelerated Population Annealing Algorithm: Frustrated Ising Antiferromagnet on the Stacked Triangular Lattice

EPJ Web of Conferences, 2016

Research paper thumbnail of PRAND: GPU accelerated parallel random number generation library: Using most reliable algorithms and applying parallelism of modern GPUs and CPUs

Computer Physics Communications, 2014

The library PRAND for pseudorandom number generation for modern CPUs and GPUs is presented. It co... more The library PRAND for pseudorandom number generation for modern CPUs and GPUs is presented. It contains both single-threaded and multi-threaded realizations of a number of modern and most reliable generators recently proposed and studied in [1, 2, 3, 4, 5] and the efficient SIMD realizations proposed in . One of the useful features for using PRAND in parallel simulations is the ability to initialize up to 10 19 independent streams. Using massive parallelism of modern GPUs and SIMD parallelism of modern CPUs substantially improves performance of the generators.

Research paper thumbnail of RNGSSELIB: Program library for random number generation, SSE2 realization

Computer Physics Communications, 2011

In this update, we present the new version of the random number generator (RNG) library RNGSSELIB... more In this update, we present the new version of the random number generator (RNG) library RNGSSELIB, which, in particular, contains fast SSE realizations of a number of modern and most reliable generators [1]. The new features are: i) Fortran compatibility and examples of using the library in Fortran; ii) new modern and reliable generators; iii) the abilities to jump ahead inside RNG sequence and to initialize up to 10 19 independent random number streams with block splitting method.

Research paper thumbnail of Evaporation and fluid dynamics of a sessile drop of capillary size

Physical Review E, 2009

Theoretical description and numerical simulation of an evaporating sessile drop are developed. We... more Theoretical description and numerical simulation of an evaporating sessile drop are developed. We jointly take into account the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the drop and the diffusion of vapor in air. A shape of the rotationally symmetric drop is determined within the quasistationary approximation. Nonstationary effects in the diffusion of the vapor are also taken into account. Simulation results agree well with the data of evaporation rate measurements for the toluene drop. Marangoni forces associated with the temperature dependence of the surface tension, generate fluid convection in the sessile drop. Our results demonstrate several dynamical stages of the convection characterized by different number of vortices in the drop. During the early stage the street of vortices arises near a surface of the drop and induces a non-monotonic spatial distribution of the temperature over the drop surface. The initial number of near-surface vortices in the drop is controlled by the Marangoni cell size which is similar to that given by Pearson for flat fluid layers. This number quickly decreases with time, resulting in three bulk vortices in the intermediate stage. The vortices finally transform into the single convection vortex in the drop, existing during about 1/2 of the evaporation time.

Research paper thumbnail of Library of random number generators based on SSE command set

Pseudo random numbers, generated recursively by deterministic rules, represent one of important i... more Pseudo random numbers, generated recursively by deterministic rules, represent one of important ingredients in algorithms for numerical simula-tions such as molecular dynamics and of Monte Carlo simulations, widely used in physics, chemistry, material science and cryptography [1]. It is a great challenge to design random number generators (RNGs) producing pseudo random numbers that behave as realizations of independent uniformly dis-tributed random variables and approximate "true randomness" [2]. In the contribution we present a library of modern and most reliable RNGs known today. Namely, the realizations of the modern generators MT19937, MRG32k3a, LFSR113, GM19-SSE, GM31-SSE and GM61-SSE are presented. MT19937 is the 2002 version of the Mersenne Twister genera-tor of Matsumoto and Nishimira [3], which is based on the recent generaliza-tions to the GFSR method. MRG32k3a is the combined multiple recursive generator proposed in [4], and LFSR113 is the combined Tausworthe ge...

Research paper thumbnail of Hydrodynamics of evaporating sessile drops

Several dynamical stages of the Marangoni convection of an evaporating sessile drop are obtained.... more Several dynamical stages of the Marangoni convection of an evaporating sessile drop are obtained. We jointly take into account the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the drop and the diffusion of vapor in air. The stages are characterized by different number of vortices in the drop and the spatial location of vortices. During the early stage the array of vortices arises near a surface of the drop and induces a non-monotonic spatial distribution of the temperature over the drop surface. The number of near-surface vortices in the drop is controlled by the Marangoni cell size, which is calculated similar to that given by Pearson for flat fluid layers. The number of vortices quickly decreases with time, resulting in three bulk vortices in the intermediate stage. The vortex structure finally evolves into the single convection vortex in the drop, existing during about 1/2 of the evaporation time. Comment: 5 pages, 3 figures, conference CCP2010

Research paper thumbnail of Periodic orbits of the ensemble of Sinai-Arnold cat maps and pseudorandom number generation

Physical Review E, 2006

We propose methods for constructing high-quality pseudorandom number generators (RNGs) based on a... more We propose methods for constructing high-quality pseudorandom number generators (RNGs) based on an ensemble of hyperbolic automorphisms of the unit two-dimensional torus (Sinai-Arnold map or cat map) while keeping a part of the information hidden. The single cat map provides the random properties expected from a good RNG and is hence an appropriate building block for an RNG, although unnecessary correlations are always present in practice. We show that introducing hidden variables and introducing rotation in the RNG output, accompanied with the proper initialization, dramatically suppress these correlations. We analyze the mechanisms of the single-cat-map correlations analytically and show how to diminish them. We generalize the Percival-Vivaldi theory in the case of the ensemble of maps, find the period of the proposed RNG analytically, and also analyze its properties. We present efficient practical realizations for the RNGs and check our predictions numerically. We also test our RNGs using the known stringent batteries of statistical tests and find that the statistical properties of our best generators are not worse than those of other best modern generators.

Research paper thumbnail of 25th IUPAP Conference on Computational Physics (CCP2013)

Journal of Physics: Conference Series, 2014

Participants of the XXV IUPAP Conference on Computational physics came to Moscow at the end of th... more Participants of the XXV IUPAP Conference on Computational physics came to Moscow at the end of the August during a hot period. It was not a hot period because of the summer; in fact, the weather was quite comfortable. It was a hot period for the atmosphere amidst scientific society in Russia, especially for scientists working for the Russian Academy of Sciences.

Research paper thumbnail of GPU-Accelerated Population Annealing Algorithm: Frustrated Ising Antiferromagnet on the Stacked Triangular Lattice

EPJ Web of Conferences, 2016

Research paper thumbnail of PRAND: GPU accelerated parallel random number generation library: Using most reliable algorithms and applying parallelism of modern GPUs and CPUs

Computer Physics Communications, 2014

The library PRAND for pseudorandom number generation for modern CPUs and GPUs is presented. It co... more The library PRAND for pseudorandom number generation for modern CPUs and GPUs is presented. It contains both single-threaded and multi-threaded realizations of a number of modern and most reliable generators recently proposed and studied in [1, 2, 3, 4, 5] and the efficient SIMD realizations proposed in . One of the useful features for using PRAND in parallel simulations is the ability to initialize up to 10 19 independent streams. Using massive parallelism of modern GPUs and SIMD parallelism of modern CPUs substantially improves performance of the generators.

Research paper thumbnail of RNGSSELIB: Program library for random number generation, SSE2 realization

Computer Physics Communications, 2011

In this update, we present the new version of the random number generator (RNG) library RNGSSELIB... more In this update, we present the new version of the random number generator (RNG) library RNGSSELIB, which, in particular, contains fast SSE realizations of a number of modern and most reliable generators [1]. The new features are: i) Fortran compatibility and examples of using the library in Fortran; ii) new modern and reliable generators; iii) the abilities to jump ahead inside RNG sequence and to initialize up to 10 19 independent random number streams with block splitting method.

Research paper thumbnail of Evaporation and fluid dynamics of a sessile drop of capillary size

Physical Review E, 2009

Theoretical description and numerical simulation of an evaporating sessile drop are developed. We... more Theoretical description and numerical simulation of an evaporating sessile drop are developed. We jointly take into account the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the drop and the diffusion of vapor in air. A shape of the rotationally symmetric drop is determined within the quasistationary approximation. Nonstationary effects in the diffusion of the vapor are also taken into account. Simulation results agree well with the data of evaporation rate measurements for the toluene drop. Marangoni forces associated with the temperature dependence of the surface tension, generate fluid convection in the sessile drop. Our results demonstrate several dynamical stages of the convection characterized by different number of vortices in the drop. During the early stage the street of vortices arises near a surface of the drop and induces a non-monotonic spatial distribution of the temperature over the drop surface. The initial number of near-surface vortices in the drop is controlled by the Marangoni cell size which is similar to that given by Pearson for flat fluid layers. This number quickly decreases with time, resulting in three bulk vortices in the intermediate stage. The vortices finally transform into the single convection vortex in the drop, existing during about 1/2 of the evaporation time.

Research paper thumbnail of Library of random number generators based on SSE command set

Pseudo random numbers, generated recursively by deterministic rules, represent one of important i... more Pseudo random numbers, generated recursively by deterministic rules, represent one of important ingredients in algorithms for numerical simula-tions such as molecular dynamics and of Monte Carlo simulations, widely used in physics, chemistry, material science and cryptography [1]. It is a great challenge to design random number generators (RNGs) producing pseudo random numbers that behave as realizations of independent uniformly dis-tributed random variables and approximate "true randomness" [2]. In the contribution we present a library of modern and most reliable RNGs known today. Namely, the realizations of the modern generators MT19937, MRG32k3a, LFSR113, GM19-SSE, GM31-SSE and GM61-SSE are presented. MT19937 is the 2002 version of the Mersenne Twister genera-tor of Matsumoto and Nishimira [3], which is based on the recent generaliza-tions to the GFSR method. MRG32k3a is the combined multiple recursive generator proposed in [4], and LFSR113 is the combined Tausworthe ge...

Research paper thumbnail of Hydrodynamics of evaporating sessile drops

Several dynamical stages of the Marangoni convection of an evaporating sessile drop are obtained.... more Several dynamical stages of the Marangoni convection of an evaporating sessile drop are obtained. We jointly take into account the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the drop and the diffusion of vapor in air. The stages are characterized by different number of vortices in the drop and the spatial location of vortices. During the early stage the array of vortices arises near a surface of the drop and induces a non-monotonic spatial distribution of the temperature over the drop surface. The number of near-surface vortices in the drop is controlled by the Marangoni cell size, which is calculated similar to that given by Pearson for flat fluid layers. The number of vortices quickly decreases with time, resulting in three bulk vortices in the intermediate stage. The vortex structure finally evolves into the single convection vortex in the drop, existing during about 1/2 of the evaporation time. Comment: 5 pages, 3 figures, conference CCP2010

Research paper thumbnail of Periodic orbits of the ensemble of Sinai-Arnold cat maps and pseudorandom number generation

Physical Review E, 2006

We propose methods for constructing high-quality pseudorandom number generators (RNGs) based on a... more We propose methods for constructing high-quality pseudorandom number generators (RNGs) based on an ensemble of hyperbolic automorphisms of the unit two-dimensional torus (Sinai-Arnold map or cat map) while keeping a part of the information hidden. The single cat map provides the random properties expected from a good RNG and is hence an appropriate building block for an RNG, although unnecessary correlations are always present in practice. We show that introducing hidden variables and introducing rotation in the RNG output, accompanied with the proper initialization, dramatically suppress these correlations. We analyze the mechanisms of the single-cat-map correlations analytically and show how to diminish them. We generalize the Percival-Vivaldi theory in the case of the ensemble of maps, find the period of the proposed RNG analytically, and also analyze its properties. We present efficient practical realizations for the RNGs and check our predictions numerically. We also test our RNGs using the known stringent batteries of statistical tests and find that the statistical properties of our best generators are not worse than those of other best modern generators.

Research paper thumbnail of 25th IUPAP Conference on Computational Physics (CCP2013)

Journal of Physics: Conference Series, 2014

Participants of the XXV IUPAP Conference on Computational physics came to Moscow at the end of th... more Participants of the XXV IUPAP Conference on Computational physics came to Moscow at the end of the August during a hot period. It was not a hot period because of the summer; in fact, the weather was quite comfortable. It was a hot period for the atmosphere amidst scientific society in Russia, especially for scientists working for the Russian Academy of Sciences.