Number of found documents: 8506
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Laplacian preconditioning of elliptic PDEs: Localization of the eigenvalues of the discretized operator
Gergelits, Tomáš; Mardal, K.-A.; Nielsen, B. F.; Strakoš, Z.
2019 - English
This contribution represents an extension of our earlier studies on the paradigmatic example of the inverse problem of the diffusion parameter estimation from spatio-temporal measurements of fluorescent particle concentration, see [6, 1, 3, 4, 5]. More precisely, we continue to look for an optimal bleaching pattern used in FRAP (Fluorescence Recovery After Photobleaching), being the initial condition of the Fickian diffusion equation maximizing a sensitivity measure. As follows, we define an optimization problem and we show the special feature (so-called complementarity principle) of the optimal binary-valued initial conditions. Available in digital repository of the ASCR
Laplacian preconditioning of elliptic PDEs: Localization of the eigenvalues of the discretized operator

This contribution represents an extension of our earlier studies on the paradigmatic example of the inverse problem of the diffusion parameter estimation from spatio-temporal measurements of ...

Gergelits, Tomáš; Mardal, K.-A.; Nielsen, B. F.; Strakoš, Z.
Ústav informatiky, 2019

On the Optimal Initial Conditions for an Inverse Problem of Model Parameter Estimation - a Complementarity Principle
Matonoha, Ctirad; Papáček, Š.
2019 - English
This contribution represents an extension of our earlier studies on the paradigmatic example of the inverse problem of the diffusion parameter estimation from spatio-temporal measurements of fluorescent particle concentration, see [6, 1, 3, 4, 5]. More precisely, we continue to look for an optimal bleaching pattern used in FRAP (Fluorescence Recovery After Photobleaching), being the initial condition of the Fickian diffusion equation maximizing a sensitivity measure. As follows, we define an optimization problem and we show the special feature (so-called complementarity principle) of the optimal binary-valued initial conditions. Available in digital repository of the ASCR
On the Optimal Initial Conditions for an Inverse Problem of Model Parameter Estimation - a Complementarity Principle

This contribution represents an extension of our earlier studies on the paradigmatic example of the inverse problem of the diffusion parameter estimation from spatio-temporal measurements of ...

Matonoha, Ctirad; Papáček, Š.
Ústav informatiky, 2019

Tourist interest in illicit zone of ice caves
Nováková, Eva; Kuda, František; Kubalíková, Lucie
2018 - English
Ledové sluje (Ice Caves) in the Podyjí National Park represents one of the most spectacular sites within the area. It consists of the large boulder field and several pseudokarst caverns on the north-western slope of the ridge that are very important from the ecological and geomorphological point of view. The access to the site is restricted for the visitors of National Park as there exists a risk of damage and disturbance of these unique phenomena; tourist can use the marked paths leading around the site, they can reach the top part of the ridge.\nCurrently, there are only several persons who have legal access to the site (employees of the National Park Administration and other researches with the permission issued by NP Administration). However, the installed sensor that counts the passages proved that the site is visited more frequently than it should be. The number of people who visit this site (situated within the first zone of National Park where there is no marked path and so the access is forbidden by decree) is quite alarming. Based on these findings, some proposals for the solution of this unfavourable situation are proposed and other possibilities how to avoid this undesirable phenomenon are discussed.\n Keywords: Podyji National Park; restricted area; passages monitoring Available in a digital repository NRGL
Tourist interest in illicit zone of ice caves

Ledové sluje (Ice Caves) in the Podyjí National Park represents one of the most spectacular sites within the area. It consists of the large boulder field and several pseudokarst caverns on the ...

Nováková, Eva; Kuda, František; Kubalíková, Lucie
Ústav geoniky, 2018

Generation of Intermittent Jet by Pulse-Modulated Synthetic Jets
Broučková, Zuzana
2018 - English
An axisymmetric air jet was excited using a pair of counter synthetic jets running in opposed direction. First, the control synthetic jets were measured alone. The driving signal was pulse modulated sinusoidal signal. After an adjustment, the primary axisymmetric jet was excited to the bifurcating mode, and its behavior was studied experimentally. For comparison purposes, a reference steady (unforced) jet from the same nozzle was also measured (Reynolds number was approximately 1300). The flow visualization and hot-wire anemometry techniques were used. Keywords: synthetic jet; pulse modulation; flow control Available at various institutes of the ASCR
Generation of Intermittent Jet by Pulse-Modulated Synthetic Jets

An axisymmetric air jet was excited using a pair of counter synthetic jets running in opposed direction. First, the control synthetic jets were measured alone. The driving signal was pulse modulated ...

Broučková, Zuzana
Ústav termomechaniky, 2018

Problem of competing risks with covariates: Application to an unemployment study
Volf, Petr
2018 - English
The study deals with the methods of statistical analysis in the situation of competing risks in the presence of regression. First, the problem of identification of marginal and joint distributions of competing random variables is recalled. The main objective is then to demonstrate that the parameters and, in particular, the correlation of competing variables, may depend on covariates. The approach is applied to solution of a real example with unemployment data. The model uses the Gauss copula and Cox’s regression model. Keywords: statistical analysis; competing risks; unemployment study Fulltext is available at external website.
Problem of competing risks with covariates: Application to an unemployment study

The study deals with the methods of statistical analysis in the situation of competing risks in the presence of regression. First, the problem of identification of marginal and joint distributions of ...

Volf, Petr
Ústav teorie informace a automatizace, 2018

Classification of distances in cosmology
Křížek, Michal; Mészáros, A.
2018 - English
In cosmology many different distances are defined: angular, comoving, Euclidean, Hubble, light-year, luminosity, Minkowski, parallax, proper motion, redshift, ... distance. There is not one single natural distance, since the universe is expanding, curved, and we look back in time. In this survey paper we will concentrate on geometrical interpretations of the above-mentioned distances. Keywords: standard cosmological model; cosmological principle; Friedmann equation; cosmological parameters; Einstein static universe Available in digital repository of the ASCR
Classification of distances in cosmology

In cosmology many different distances are defined: angular, comoving, Euclidean, Hubble, light-year, luminosity, Minkowski, parallax, proper motion, redshift, ... distance. There is not one single ...

Křížek, Michal; Mészáros, A.
Matematický ústav, 2018

Finite element modeling of the signal propagation in a thin tube and comparison with experimental data
Kruisová, Alena; Kolman, Radek; Trnka, Jan; Mračko, Michal
2018 - English
In finite element modeling of wave propagation problems, both the spatial and temporal discretization lead to dispersion errors. It means that the phase velocity of propagated wave is related to its frequency. In framework of temporal-spatial dispersion analysis, the time step size for implicit time integration method based on the Newmark method is proposed for linear and quadratic serendipity plane finite elements. In this paper, we verify the theoretical dispersion analysis by elastic wave propagation in thin tube, where experimental results are known. Such time step size was used in finite element modeling of the stress wave propagating in this thin steel tube, the results of simulations were compared with experimental results. Keywords: wave propagation; finite element method; dispersion errors Available at various institutes of the ASCR
Finite element modeling of the signal propagation in a thin tube and comparison with experimental data

In finite element modeling of wave propagation problems, both the spatial and temporal discretization lead to dispersion errors. It means that the phase velocity of propagated wave is related to its ...

Kruisová, Alena; Kolman, Radek; Trnka, Jan; Mračko, Michal
Ústav termomechaniky, 2018

Experimental investigation of fault tolerant converter connected to unbalanced grid
Valouch, Viktor; Šimek, Petr; Škramlík, Jiří
2018 - English
A model of the three-phase voltage converter for simulation of its modes of operation in standard as wellas fault states is presented. The presented model can be used to simulate steady-states and also transients at dc and ac side of the grid-connected converter. Based on simulation, an algorithm was designed to identify and localize a fault in some phase of the three-phase converter. Rules how to modify hardware, and control and modulation strategies to hold the converter in operation after the fault are presented and tested. the algorithm was experimentally verified. Keywords: grid-connected converter; fault identification and localization; reconfiguration Available at various institutes of the ASCR
Experimental investigation of fault tolerant converter connected to unbalanced grid

A model of the three-phase voltage converter for simulation of its modes of operation in standard as wellas fault states is presented. The presented model can be used to simulate steady-states and ...

Valouch, Viktor; Šimek, Petr; Škramlík, Jiří
Ústav termomechaniky, 2018

Influence of excitation frequency and pulse width on blade vibration
Voronova, Evgeniya; Maturkanič, Dušan
2018 - English
The paper describes results of measuring of blade vibration characteristics excitation by one electromagnet at harmonic regime.The measurements were performed in the laboratory of rotational laser vibrometry originated at the Institute of Thermomechanics AS CR, v.v.i.\n Keywords: vibration; blade; laser; turbine Available at various institutes of the ASCR
Influence of excitation frequency and pulse width on blade vibration

The paper describes results of measuring of blade vibration characteristics excitation by one electromagnet at harmonic regime.The measurements were performed in the laboratory of rotational laser ...

Voronova, Evgeniya; Maturkanič, Dušan
Ústav termomechaniky, 2018

Cultural heritage and geodiversity of landforms in the landscape of the Archdiocese of Olomouc
Kirchner, Karel; Kuda, František; Kubalíková, Lucie; Havlíček, M.; Machar, I.; Pechanec, V.
2018 - English
Within the framework of the NAKI II project – Cultural heritage of landscape of the Archdiocese of Olomouc - research, presentation and management (DGB 16P02B014), we focus on the results that will contribute to the sustainable development of regional cultural identity through applied cultural heritage research in the cultural landscape of the area of interest. As part of the material cultural heritage, we include the landforms that originated from the conscious activity of man - the anthropogenic relief forms. These landforms complement the geodiversity of the landscape and are referred to as secondary geodiversity. Therefore, their identification and interpretation will make it possible to complement and enhance the diversity of cultural heritage and to specify the development of the cultural landscape. The first results from the area of Central Moravia will be presented with the using of the historical maps, the digital model of the relief DMR5G and the field research. Keywords: cultural heritage; secondary geodiversity; Archdiocese of Olomouc Available in a digital repository NRGL
Cultural heritage and geodiversity of landforms in the landscape of the Archdiocese of Olomouc

Within the framework of the NAKI II project – Cultural heritage of landscape of the Archdiocese of Olomouc - research, presentation and management (DGB 16P02B014), we focus on the results that will ...

Kirchner, Karel; Kuda, František; Kubalíková, Lucie; Havlíček, M.; Machar, I.; Pechanec, V.
Ústav geoniky, 2018

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