67 research outputs found
Model of the Phase Transition Mimicking the Pasta Phase in Cold and Dense Quark-Hadron Matter
A simple mixed phase model mimicking so-called "pasta" phases in the
quark-hadron phase transition is developed and applied to static neutron stars
for the case of DD2 type hadonic and NJL type quark matter models. The
influence of the mixed phase on the mass-radius relation of the compact stars
is investigated. Model parameters are chosen such that the results are in
agreement with the observational constraints for masses and radii of pulsars.Comment: 6 pages, 4 figure
Performance Analysis of Effective Symbolic Methods for Solving Band Matrix SLAEs
This paper presents an experimental performance study of implementations of
three symbolic algorithms for solving band matrix systems of linear algebraic
equations with heptadiagonal, pentadiagonal, and tridiagonal coefficient
matrices. The only assumption on the coefficient matrix in order for the
algorithms to be stable is nonsingularity. These algorithms are implemented
using the GiNaC library of C++ and the SymPy library of Python, considering
five different data storing classes. Performance analysis of the
implementations is done using the high-performance computing (HPC) platforms
"HybriLIT" and "Avitohol". The experimental setup and the results from the
conducted computations on the individual computer systems are presented and
discussed. An analysis of the three algorithms is performed.Comment: 7 pages, 9 tables, 4 figure
Effective Methods for Solving Band SLEs after Parabolic Nonlinear PDEs
A class of models of heat transfer processes in a multilayer domain is
considered. The governing equation is a nonlinear heat-transfer equation with
different temperature-dependent densities and thermal coefficients in each
layer. Homogeneous Neumann boundary conditions and ideal contact ones are
applied. A finite difference scheme on a special uneven mesh with a
second-order approximation in the case of a piecewise constant spatial step is
built. This discretization leads to a pentadiagonal system of linear equations
(SLEs) with a matrix which is neither diagonally dominant, nor positive
definite. Two different methods for solving such a SLE are developed --
diagonal dominantization and symbolic algorithms.Comment: 4 pages, 1 figure, 1 tabl
Bayesian Analysis for Extracting Properties of the Nuclear Equation of State from Observational Data including Tidal Deformability from GW170817
We develop a Bayesian analysis method for selecting the most probable
equation of state under a set of constraints from compact star physics, which
now include the tidal deformability from GW170817. We apply this method for the
first time to a two-parameter family of hybrid equations of state that is based
on realistic models for the hadronic phase (KVORcut02) and the quark matter
phase (SFM) which produce a third family of hybrid stars in the
mass-radius diagram. One parameter () characterizes the screening of
the string tension in the string-flip model of quark matter while the other
() belongs to the mixed phase construction that mimics the
thermodynamics of pasta phases and includes the Maxwell construction as a
limiting case for . We present the corresponding results for
compact star properties like mass, radius and tidal deformabilities and use
empirical data for them in the newly developed Bayesian analysis method to
obtain the probabilities for the model parameters within their considered
range.Comment: 8 pages, 4 figures, version accepted for publication in univers
An Algorithm for the Simulations of the Magnetized Neutron Star Cooling
The model and algorithm for the cooling of the magnetized neutron stars are
presented. The cooling evolution described by system of parabolic partial
differential equations with non-linear coefficients is solved using Alternating
Direction Implicit method. The difference scheme and the preliminary results of
simulations are presented.Comment: 6 pages, 4 figures, accepted to the European Physical Journal Web of
Conferences as a contribution of the International Conference Mathematical
Modeling and Computational Physics 2015 (High Tatra Mountains, Slovakia, July
13 - July 17, 2015, http://web.tuke.sk/mmcp/mmcp2015/
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