Příspěvky z konference

Nejnovější přírůstky:
2019-05-16
18:17
Application of the Infinitely Many Times Repeated BNS Update and Conjugate Directions to Limited-Memory Optimization Methods
Vlček, Jan ; Lukšan, Ladislav
To improve the performance of the L-BFGS method for large scale unconstrained optimization, repeating of some BFGS updates was proposed. Since this can be time consuming, the extra updates need to be selected carefully. We show that groups of these updates can be repeated infinitely many times under some conditions, without a noticeable increase of the computational time; the limit update is a block BFGS update. It can be obtained by solving of some Lyapunov matrix equation whose order can be decreased by application of vector corrections for conjugacy. Global convergence of the proposed algorithm is established for convex and sufficiently smooth functions. Numerical results indicate the efficiency of the new method.

Úplný záznam
2019-05-16
18:17
Geografické horizonty Kosmovy Kroniky Čechů
Hasil, Jan
Článek prezentuje pokus o strukturální (historicko-geografickou) analýzu nejstarší české kroniky, Kosmovy Kroniky Čechů. Na základě prostorové analýzy byly rozpoznány čtyři geografické horizonty textu: mytický, legendární, historický a autooptický.

Úplný záznam
2019-05-16
18:17
Reliable computation and local mesh adaptivity in limit analysis
Sysala, Stanislav ; Haslinger, Jaroslav ; Repin, S.
The contribution is devoted to computations of the limit load for a perfectly plastic model with the von Mises yield criterion. The limit factor of a prescribed load is defined by a specific variational problem, the so-called limit analysis problem. This problem is solved in terms of deformation fields by a penalization, the finite element and the semismooth Newton methods. From the numerical solution, we derive a guaranteed upper bound of the limit factor. To achieve more accurate results, a local mesh adaptivity is used.

Úplný záznam
2019-05-16
18:17
Multivariate smooth interpolation that employs polyharmonic functions
Segeth, Karel
We study the problém of construction of the smooth interpolation formula presented as the minimizer of suitable functionals subject to interpolation constraints. We present a procedure for determining the interpolation formula that in a natural way leads to a linear combination of polyharmonic splines complemented with lower order polynomials therms. In general, such formulae can be very useful e.g. in geographic information systems or computer aided geometric design. A simple computational example is presented.

Úplný záznam
2019-05-16
18:17
Katolický sjezd 1935 jako vyjádření nejen modernizace katolické církve v meziválečném Československu
Pehr, Michal
Příspěvek analyzuje události katolického sjezdu v Československu v roce 1935, který lze považovat za vyvrcholení vývoje katolické církve v samostatné Československé republice.

Úplný záznam
2019-05-16
18:17
Influence of Surface Treatment of Thin-Film Composite Membrane on Separation of Carbon Dioxide from Biogas.
Morávková, Lenka ; Kárászová, Magda ; Petrusová, Zuzana ; Izák, Pavel
The effect of the various wetting procedure on the membrane performance was studied [1]. Spraying is clearly more efficient than spreading water on the top of the membrane with a brush and results in higher methane purity. Spraying ensures a more uniform distribution of the water on the skin layer of the membrane, leading to much higher CO2 permeation through the membrane and higher CH4 content in the retentate stream.
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Úplný záznam
2019-05-16
18:17
Instrumentation for study of nanomaterials in NPI REZ (New laboratory for material study in Nuclear Physics Institute in REZ)
Bejšovec, Václav ; Cannavó, Antonino ; Ceccio, Giovanni ; Hnatowicz, Vladimír ; Horák, Pavel ; Lavrentiev, Vasyl ; Macková, Anna ; Tomandl, Ivo ; Torrisi, Alfio ; Vacík, Jiří
Nano-sized materials become irreplaceable component of a number of devices for every aspect of human life. The development of new materials and deepening of the current knowledge require a set of specialized techniques-deposition methods for preparation/modification of the materials and analytical tools for proper understanding of their properties. A thoroughly equipped research centers become the requirement for the advance and development not only in nano-sized field. The Center of Accelerators and Nuclear Analytical Methods (CANAM) in the Nuclear Physics Institute (NPI) comprises a unique set of techniques for the synthesis or modification of nanostructured materials and systems, and their characterization using ion beam, neutron beam and microscopy imaging techniques. The methods are used for investigation of a broad range of nano-sized materials and structures based on metal oxides, nitrides, carbides, carbon-based materials (polymers, fullerenes, graphenes, etc.) and nano-laminate composites (MAX phases). These materials can be prepared at NPI using ion beam sputtering, physical vapor deposition and molecular beam epitaxy. Based on the deposition method and parameters, the samples can be tuned to possess specific properties, e.g., composition, thickness (nm-μm), surface roughness, optical and electrical properties, etc. Various nuclear analytical methods are applied for the sample characterization. RBS, RBS-channeling, PIXE, PIGE, micro-beam analyses and Transmission Spectroscopy are accomplished at the Tandetron 4130MC accelerator, and additionally the Neutron Depth Profiling (NDP) and Prompt Gamma Neutron Activation (PGNA) analyses are performed at an external neutron beam from the LVR-15 research reactor. The multimode AFM facility provides further surface related information, magnetic/electrical properties with nano-metric precision, nano-indentation, etc.

Úplný záznam
2019-04-29
09:26
Strategies for computation of Lyapunov exponents estimates from discrete data
Fischer, Cyril ; Náprstek, Jiří
The Lyapunov exponents (LE) provide a simple numerical measure of the sensitive dependence of the dynamical system on initial conditions. The positive LE in dissipative systems is often regarded as an indicator of the occurrence of deterministic chaos. However, the values of LE can also help to assess stability of particular solution branches of dynamical systems. The contribution brings a short review of two methods for estimation of the largest LE from discrete data series. Two methods are analysed and their freely available Matlab implementations are tested using two sets of discrete data: the sampled series of the Lorenz system and the experimental record of the movement of a heavy ball in a spherical cavity. It appears that the most important factor in LE estimation from discrete data series is quality of the available record.

Úplný záznam
2019-04-29
09:26
Polycyklické aromatické uhlovodíky v PM1 aerosolu na 6 lokalitách v České republice
Křůmal, Kamil ; Mikuška, Pavel
PAHs byly měřeny v zimní sezóně ve městech Ostrava-Radvanice (průmyslová lokalita), Brno, Mladá Boleslav, Kladno-Švermov, Čelákovice, Košetice (pozaďová lokalita). Z koncentrací PAHs v PM1 aerosolu byly počítány rizika vzniku rakoviny plic.

Úplný záznam
2019-04-29
09:26
Stanovení rychlých změn koncentrací těkavých organických sloučenin pomocí difúzního denuderu
Křůmal, Kamil ; Mikuška, Pavel
Stanovení rychlých změn koncentrací těkavých organických sloučenin bylo provedeno využitím difúzního denuderu se stékajícím filmem kapaliny, který umožňuje odběr vzorků v časových intervalech již od 2 minut.

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