
Conformal symmetry and vortices in graphene
Kůs, Pavel ; Iorio, Alfredo (advisor) ; Jizba, Petr (referee)
This study provides an introductory insight into the complex field of graphene and its relativisticlike behaviour. The thesis is opened by an overview to this topic and draws special attention to interesting nontopological vortex solutions of the Liouville equation found by P. A. Horváthy and J.C. Yéra, which emerge in a context of the ChernSimons theory [1], [2] and have been put into context of graphene [3], [4]. We introduce the massless Dirac field theory, well describing electronic properties of graphene in the low energy limit, and point to the fact that the action of the massless Dirac field is invariant under Weyl transformations, which has farreaching consequences. When the graphene membrane is suitably deformed, we assume that the correct description is that of a Dirac field on a curved spacetime. In particular, an important case is that of conformally flat 2+1dimensional spacetimes. These are obtained when the spatial part of the metric describes a surface of constant intrinsic curvature [3]. In other words, the conformal factor of such spatial metrics has to satisfy the Liouville equation, an important equation of mathematical physics. In this work, we have identified the kind of surfaces to which the Horváthy Yéra conformal factors, above recalled, correspond, and have provided...


Programs and Algorithms of Numerical Mathematics 18 : Janov nad Nisou, June 1924, 2016 : proceedings of seminar
Chleboun, J. ; Kůs, Pavel ; Přikryl, Petr ; Segeth, Karel ; Šístek, Jakub ; Vejchodský, Tomáš
This book comprises papers that originated from the invited lectures, survey lectures, short communications, and posters presented at the 18th seminar Programs and Algorithms of Numerical Mathematics (PANM) held in Janov nad Nisou, Czech Republic, June 1924, 2016. All the papers have been peerreviewed. The seminar was organized by the Institute of Mathematics of the Czech Academy of Sciences under the auspices of EUMATHSIN.cz, Czech Network for Mathematics in Industry. It continued the previous seminars on mathematical software and numerical methods held (biennially, with only one exception) in Al šovice, Bratří kov, Janov nad Nisou, Ko řenov, L ázně Libverda, Dolní Maxov, and Prague in the period 19832014. The objective of this series of seminars is to provide a forum for presenting and discussing advanced theoretical as well as practical topics in numerical analysis, computer implementation of algorithms, new approaches to mathematical modeling, and single or multiprocessor applications of computational methods.


Programs and Algorithms of Numerical Mathematics 19 : Hejnice, June 2429, 2018 : proceedings of seminar
Chleboun, J. ; Kůs, Pavel ; Přikryl, Petr ; Rozložník, Miroslav ; Segeth, Karel ; Šístek, Jakub ; Vejchodský, Tomáš
These proceedings contain peerreviewed papers that are based on the invited lectures, survey lectures, short communications, and posters presented at the 19th seminar Programs and Algorithms of Numerical Mathematics (PANM) held in the International Center for Spiritual Rehabilitation, Hejnice, Czech Republic, June 2429, 2018. The seminar was organized by the Institute of Mathematics of the Czech Academy of Sciences under the auspices of EUMATHSIN.cz, Czech Network for Mathematics in Industry, and with the financial support provided by the RSJ Foundation. It continued the previous seminars on mathematical software and numerical methods held (biennially, with only one exception) in Alšovice, Bratříkov, Janov nad Nisou, Kořenov, Lázně Libverda, Dolní Maxov, and Prague in the period 19832016. The objective of this series of seminars is to provide a forum for presenting and discussing advanced topics in numerical analysis, computer implementation of numerical algorithms, new approaches to mathematical modeling, and single or multiprocessor applications of computational methods.


Automatic hpadaptivity on Meshes with ArbitraryLevel Hanging Nodes in 3D
Kůs, Pavel
The thesis is concerned with theoretical and practical aspects of the hp adaptive finite element method for solving elliptic and electromagnetic prob lems described by partial differential equations in three spatial dimensions. Besides the standard element refinements, the hpadaptivity allows indepen dent adaptation of degrees of the polynomial approximation as well. This leads to exponentially fast convergence even for problems with singularities. The efficiency of the hpadaptivity is enhanced even more by the ability of the algorithm to work with meshes with arbitrarylevel hanging nodes. This generality, however, leads to great complexity of the implementation. There fore, the thesis concentrates on the mathematical analysis of algorithms that have led to successful implementation of the method. In addition, the the sis discusses the numerical integration in 3D and the implementation of the method itself. Finally, numerical results obtained by this new implemen tation are presented. They confirm advantages of hpadaptivity on meshes with arbitrarylevel hanging nodes. 1


Automatic hpadaptivity on Meshes with ArbitraryLevel Hanging Nodes in 3D
Kůs, Pavel ; Vejchodský, Tomáš (advisor) ; Segeth, Karel (referee) ; Dolejší, Vít (referee)
The thesis is concerned with theoretical and practical aspects of the hp adaptive finite element method for solving elliptic and electromagnetic prob lems described by partial differential equations in three spatial dimensions. Besides the standard element refinements, the hpadaptivity allows indepen dent adaptation of degrees of the polynomial approximation as well. This leads to exponentially fast convergence even for problems with singularities. The efficiency of the hpadaptivity is enhanced even more by the ability of the algorithm to work with meshes with arbitrarylevel hanging nodes. This generality, however, leads to great complexity of the implementation. There fore, the thesis concentrates on the mathematical analysis of algorithms that have led to successful implementation of the method. In addition, the the sis discusses the numerical integration in 3D and the implementation of the method itself. Finally, numerical results obtained by this new implemen tation are presented. They confirm advantages of hpadaptivity on meshes with arbitrarylevel hanging nodes. 1


Numerical solution of convectiondiffusion equations with the aid of adaptive timespace higher order methods
Kůs, Pavel ; Felcman, Jiří (referee) ; Dolejší, Vít (advisor)
This thesis deals with solution of scalar nonlinear convectiondiffusion equation with aid of discontinuous Galerkin method. It's aim is to implement an adaptive choice of time step. To do this, we derived 2 sufficiently stable methods for solution of systems of ordinary differential equations obtained by space semidicretization, which is carried out by the discontinuous Galerkin method. Using those two approximate solutions, we estimate local error of discretization. Using it, we are able to choose following time step in such way, that local error is approximately equal to given tolerance. Several numerical simulations were carried out to check properties of this method.

 
 
 

Integration in higherorder finite element method in 3D
Kůs, Pavel
Integration of higherorder basis functions is an important issue, that is not as straightforward as it may seem. In traditional loworder FEM codes, the bulk of computational time is a solution of resulting system of linear equations. In the case of higherorder elements the situation is different. Especially in three dimensions the time of integration may represent significant part of the computation.
