25 research outputs found
Nonabelian dualization of plane wave backgrounds
We investigate plane-parallel wave metrics from the point of view of their
(Poisson-Lie) T-dualizability. For that purpose we reconstruct the metrics as
backgrounds of nonlinear sigma models on Lie groups. For construction of dual
backgrounds we use Drinfel'd doubles obtained from the isometry groups of the
metrics. We find dilaton fields that enable to satisfy the vanishing beta
equations for the duals of the homogenous plane-parallel wave metric. Torsion
potentials or B-fields, invariant w.r.t. the isometry group of Lobachevski
plane waves are obtained by the Drinfel'd double construction. We show that a
certain kind of plurality, different from the (atomic) Poisson-Lie T-plurality,
may exist in case that metrics admit several isometry subgroups having the
dimension of the Riemannian manifold. An example of that are two different
backgrounds dual to the homogenous plane-parallel wave metric.Comment: 18 page
Classical solutions of sigma models in curved backgrounds by the Poisson-Lie T-plurality
Classical equations of motion for three-dimensional sigma-models in curved
background are solved by a transformation that follows from the Poisson-Lie
T-plurality and transform them into the equations in the flat background.
Transformations of coordinates that make the metric constant are found and used
for solving the flat model. The Poisson-Lie transformation is explicitly
performed by solving the PDE's for auxiliary functions and finding the relevant
transformation of coordinates in the Drinfel'd double. String conditions for
the solutions are preserved by the Poisson-Lie transformations. Therefore we
are able to specify the type of sigma-model solutions that solve also equations
of motion of three dimensional relativistic strings in the curved backgrounds.
Simple examples are given
Flat coordinates and dilaton fields for three--dimensional conformal sigma models
Riemannian coordinates for flat metrics corresponding to three--dimensional
conformal Poisson--Lie T--dualizable sigma models are found by solving partial
differential equations that follow from the transformations of the connection
components. They are then used for finding general forms of the dilaton fields
satisfying the vanishing beta equations of the sigma models.Comment: 16 pages, no figure
The educational computer program for assignment task analyses
Předkládaná diplomová práce se zabývá problematikou distribučních úloh, přesněji přiřazovacím problémem řešeným Maďarskou metodou a okružním dopravním problémem ("problém obchodního cestujícího"). Cílem této práce je praktické zpracování daných úloh v jazyce C++. Přiřazovací problém formou výukového programu, pomocí kterého by měl být uživatel schopen pochopit a naučit se dané problematice. Druhá část programu se zaměřuje na eliminaci parciálních smyček u okružního dopravního problému vznikajících při řešení obecnou Maďarskou metodou.ObhájenoThe present thesis deals with the distribution problems, more specificly assignment problem to be solved by Hungarian method and traveling salesman problem. The aim of this work is the practical solution of these tasks in C ++. Assignment problem through the educational program thanks to which the user should be able to understand and learn the issue. The second part of the program focuses on the elimination of partial loops in traveling salesman problem arising in dealing with the general Hungarian method
The conception of sport training for young judoists
Title: The Conception of Sports Training for Young Judoists Objectives: The main aim of this work is to describe and assess a suitable conception of training for young judoists. The paper also points out the effective methods of training and the aspects that need to be prioritized and avoided by the judo instructor. The focus is also on the control of training and the levels of general movement skills of the selected group. Methods: The author used various methods of data collection and the analysis of technical bibliografy which was focused on general sports preparations, study of available materials for judo training and own practice of the author. The materials and the bibliography were analyzed and structured according to applicability to the specific subjects. Results: The results of this paper emphasize the importance of development of various aspects while training young pupils. The results also stress the necessity of frequent training controls. Keywords: judo, training, young judoists, conception, batery of test
The conception of sport training for young judoists
Title: The Conception of Sports Training for Young Judoists Objectives: The main aim of this work is to describe and assess a suitable conception of training for young judoists. The paper also points out the effective methods of training and the aspects that need to be prioritized and avoided by the judo instructor. The focus is also on the control of training and the levels of general movement skills of the selected group. Methods: The author used various methods of data collection and the analysis of technical bibliografy which was focused on general sports preparations, study of available materials for judo training and own practice of the author. The materials and the bibliography were analyzed and structured according to applicability to the specific subjects. Results: The results of this paper emphasize the importance of development of various aspects while training young pupils. The results also stress the necessity of frequent training controls. Keywords: judo, training, young judoists, conception, batery of test
Rotating machines and their insulation systems
Bakalářská práce se věnuje izolačnímu systému točivých elektrických strojů. Práce pojednává o točivých elektrických strojích, jejich rozdělení, principy a konstrukcemi. Dále se věnuje vlastnostem izolačních materiálů (elektrická pevnost, rezistivita, relativní permitivita, dielektrické ztráty, ztrátový činitel tg?), popisuje výbojovou činnost vznikající u vedení strojů. Popisuje a porovnává hlavní výrobní technologie izolací točivých elektrických strojů Resin ? Rich a VPI a materiály použité pro jejich výrobu.Katedra technologií a měřeníObhájenoBachelor thesis deals with insulation system of electrical rotating machines. The work discusses the rotating electrical machines, their classification, principles and structures. Further, the work deals with the properties of insulating materials (dielectric strength, resistivity, relative permittivity, dielectric loss, disipation factor tg?). The thesis describes the partial discharge activity in the machines machines. The work compares the main production technology of rotating electrical machines insulation - Resin - Rich and VPI and also materials which are used for their production