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Poruchy skleněných výplní stropu nad studovnou Knihovny AV ČR
Drdácký, Miloš; Hlobil, Michal
2018 - Czech
Ve výzkumné zprávě je popsán současný stav poškození skleněných výplní stropu nad studovnou Knihovny AV ČR. Prasklé skleněné tabule jsou zdokumentovány a je navrženo opatření, které by mělo jejich budoucí porušení minimalizovat. The report describes the current state of the damaged glass panels above the study room in the library of the Czech Academy of Sciences. The fractured glass panels are documented and a recommendation is given to minimize their future damage. Keywords: fracture; glass panel; steel grid Available at various institutes of the ASCR
Poruchy skleněných výplní stropu nad studovnou Knihovny AV ČR

Ve výzkumné zprávě je popsán současný stav poškození skleněných výplní stropu nad studovnou Knihovny AV ČR. Prasklé skleněné tabule jsou zdokumentovány a je navrženo opatření, které by mělo jejich ...

Drdácký, Miloš; Hlobil, Michal
Ústav teoretické a aplikované mechaniky, 2018

Vliv organických látek na charakter agregátů tvořených koagulací/flokulací při úpravě vody
Filipenská, Monika; Pivokonská, Lenka; Vašatová, Petra; Pivokonský, Martin
2018 - Czech
Cílem práce bylo popsat vliv různých znečišťujících příměsí (kaolinitové částice, COM peptidy/proteiny a jejich směs) na velikost, velikostní distribuci, tvar a strukturu agregátů tvořených v proměnných hydrodynamických podmínkách (různá gradient rychlosti) v konečné fázi vývoje agregace, tzv. steady state. Jako míchací zařízení byl zvolen Taylor-Couettův reaktor, který umožňuje neinvazivní pozorování agregátů. Vlastnosti agregátů byly vyhodnocovány metodou obrazové analýzy. Bylo zjištěno, že velikost a tvar agregátů je závislá na typu koagulačního činidla, typu koagulované přímesi a aplikovaném gradientu rychlosti. Železité koagulační činidlo produkuje větší a méně pravidelné agregáty než činidlo hlinité. Podle příměsi roste velikost (zároveň klesá kompaktnost a roste neuspořádanost) agregátů v pořadí kaolinit < COM < kaolinit + COM. Bylo zjištěno, že velikost agregátů se na aplikovaném gradientu rychlosti nemění plynule, jak bylo doposud předpokládání, ale při překročení hodnoty tzv. kritických gradientů rychlosti, dochází k její prudké změně. Změny ve velikosti agregátů se liší v závislosti na charakteru koagulovaných příměsí a byly vysvětleny pomocí rozdílných interakcí mezi znečišťující příměsí a koagulačním činidlem. Available at various institutes of the ASCR
Vliv organických látek na charakter agregátů tvořených koagulací/flokulací při úpravě vody

Cílem práce bylo popsat vliv různých znečišťujících příměsí (kaolinitové částice, COM peptidy/proteiny a jejich směs) na velikost, velikostní distribuci, tvar a strukturu agregátů tvořených v ...

Filipenská, Monika; Pivokonská, Lenka; Vašatová, Petra; Pivokonský, Martin
Ústav pro hydrodynamiku, 2018

Dynamic Bayesian Networks for the Classification of Sleep Stages
Vomlel, Jiří; Kratochvíl, Václav
2018 - English
Human sleep is traditionally classified into five (or six) stages. The manual classification is time consuming since it requires knowledge of an extensive set of rules from manuals and experienced experts. Therefore automatic classification methods appear useful for this task. In this paper we extend the approach based on Hidden Markov Models by relating certain features not only to the current time slice but also to the previous one. Dynamic Bayesian Networks that results from this generalization are thus capable of modeling features related to state transitions. Experiments on real data revealed that in this way we are able to increase the prediction accuracy. Keywords: Dynamic Bayesian Network; Sleep Analysis Fulltext is available at external website.
Dynamic Bayesian Networks for the Classification of Sleep Stages

Human sleep is traditionally classified into five (or six) stages. The manual classification is time consuming since it requires knowledge of an extensive set of rules from manuals and experienced ...

Vomlel, Jiří; Kratochvíl, Václav
Ústav teorie informace a automatizace, 2018

Asymmetry of the response probability density of a system with parametric random noises
Náprstek, Jiří; Fischer, Cyril
2018 - English
Recording of time variable processes is accompanied by various internal disturbing effects as a rule. They influence parameters of the measuring facility, transducer-device transmission, etc. These parasitic processes are usually of the random character and, consequently, they exercise as parametric noises. Moreover, the input signal mostly consists of a useful signal which can be taken as composed from deterministic and random additive part. Various combinations of these noises are the origin of random and also systematic measuring errors which can have under certain circumstances a cumulative character, deteriorate the output signal quality and can lead finally to the stochastic stability loss. These effects can be theoretically described using differential systems with stochastic coefficients and stochastic right hand side considering all input and output processes to be of the Markov type. Keywords: random vibration; signal reconstruction; parametric noise; response asymmetry Available at various institutes of the ASCR
Asymmetry of the response probability density of a system with parametric random noises

Recording of time variable processes is accompanied by various internal disturbing effects as a rule. They influence parameters of the measuring facility, transducer-device transmission, etc. These ...

Náprstek, Jiří; Fischer, Cyril
Ústav teoretické a aplikované mechaniky, 2018

OLGA – efficient full wave code for the coupling of LH grills
Preinhaelter, Josef; Hillairet, J.; Urban, Jakub
2018 - English
The full wave code OLGA, for determining the coupling of a single row lower hybrid launcher (waveguide grills) to the plasma, is extended to handle multirow multijunction active passive structures (like the C3 and C4 launchers on TORE SUPRA) by implementing the scattering matrix formalism. The extended code is still computationally fast because of the use of (i) 2D splines of the plasma surface admittance in the accessibility region of the k-space, (ii) high order Gaussian quadrature rules for the integration of the coupling elements and (iii) utilizing the symmetries of the coupling elements in the multiperiodic structures. The extended OLGA code is benchmarked against the ALOHA-1D, ALOHA-2D and TOPLHA codes for the coupling of the C3 and C4 TORE SUPRA launchers for several plasma configurations derived from reflectometry and interferometery. Unlike nearly all codes (except the ALOHA-1D code), OLGA does not require large computational resources and can be used for everyday usage in planning experimental runs. In particular, it is shown that the OLGA code correctly handles the coupling of the C3 and C4 launchers over a very wide range of plasma densities in front of the grill. Keywords: lower hybrid waves; coupling; large multirow multijunction grills; tokamak; full-wave Fulltext is available at external website.
OLGA – efficient full wave code for the coupling of LH grills

The full wave code OLGA, for determining the coupling of a single row lower hybrid launcher (waveguide grills) to the plasma, is extended to handle multirow multijunction active passive structures ...

Preinhaelter, Josef; Hillairet, J.; Urban, Jakub
Ústav fyziky plazmatu, 2018

Neglected gravitational redshift in detections of gravitational waves
Křížek, Michal; Somer, L.
2018 - English
In 2016, the letter [1] about the first detection of gravitational waves was published. They were generated by two merging black holes that had approximately 36 and 29 Sun’s masses. However, the authors have not taken into account a large gravitational redshift of this binary system, which is a direct consequence of time dilation in a strong gravitational field. Thus the proposed masses are overestimated. In our paper we also give other arguments for this statement. Keywords: gravitational redshift; time dilatation; black holes; wavelets Available in digital repository of the ASCR
Neglected gravitational redshift in detections of gravitational waves

In 2016, the letter [1] about the first detection of gravitational waves was published. They were generated by two merging black holes that had approximately 36 and 29 Sun’s masses. However, the ...

Křížek, Michal; Somer, L.
Matematický ústav, 2018

How to down-weight observations in robust regression: A metalearning study
Kalina, Jan; Pitra, Zbyněk
2018 - English
Metalearning is becoming an increasingly important methodology for extracting knowledge from a data base of available training data sets to a new (independent) data set. The concept of metalearning is becoming popular in statistical learning and there is an increasing number of metalearning applications also in the analysis of economic data sets. Still, not much attention has been paid to its limitations and disadvantages. For this purpose, we use various linear regression estimators (including highly robust ones) over a set of 30 data sets with economic background and perform a metalearning study over them as well as over the same data sets after an artificial contamination. We focus on comparing the prediction performance of the least weighted squares estimator with various weighting schemes. A broader spectrum of classification methods is applied and a support vector machine turns out to yield the best results. While results of a leave-1-out cross validation are very different from results of autovalidation, we realize that metalearning is highly unstable and its results should be interpreted with care. We also focus on discussing all possible limitations of the metalearning methodology in general. Keywords: metalearning; robust statistics; linear regression; outliers Available at various institutes of the ASCR
How to down-weight observations in robust regression: A metalearning study

Metalearning is becoming an increasingly important methodology for extracting knowledge from a data base of available training data sets to a new (independent) data set. The concept of metalearning is ...

Kalina, Jan; Pitra, Zbyněk
Ústav informatiky, 2018

Structure investigation of hydrogels using a cryo-SEM
Adámková, Kateřina; Hrubanová, Kamila; Samek, Ota; Trudičová, M.; Sedláček, P.; Krzyžánek, Vladislav
2018 - English
Hydrogels can be characterized as elastic hydrophilic polymer chains connected in network\nwhich are able to swell notably when exposed to aqueous media by absorbing considerable\namounts of water. Besides being a constituent of living organisms, nowadays, there are\nvarious fields hydrated polymers (e.g. polyvinyl alcohol, collagen, and starch) can be utilized\n– in both biological and non-biological form. Classic examples of such applications are\nhuman health and cosmetics (contact lenses, wound healing dressings and artificial\nreplacement tissues – skin, arterial grafts, cornea and spinal disc replacement), pharmacy\n(drug delivery systems), bioengineering, food industry, agriculture etc. Also, hydrogels\ncan reversibly change their shape when being exposed to a temperature change. Available at various institutes of the ASCR
Structure investigation of hydrogels using a cryo-SEM

Hydrogels can be characterized as elastic hydrophilic polymer chains connected in network\nwhich are able to swell notably when exposed to aqueous media by absorbing considerable\namounts of water. ...

Adámková, Kateřina; Hrubanová, Kamila; Samek, Ota; Trudičová, M.; Sedláček, P.; Krzyžánek, Vladislav
Ústav přístrojové techniky, 2018

Thermal desorption spectroscopy in prototype furnace for chemical vapor deposition
Průcha, Lukáš; Daniel, Benjamin; Piňos, Jakub; Mikmeková, Eliška
2018 - English
Cleaning of the sample surfaces is crucial for scanning electron microscopy, especially for\nlow energy electron microscopy or for the deposition of thin layers, such as graphene,\nwhere surface has to be well prepared. In the best case, every unwanted particle should be\ncleaned from the sample surface for best low energy electron microscopy observation or thin\nfilm deposition. Unfortunately, the standard cleaning procedures can leave residues on the\nsample surface. This work is focused on thermal desorption spectroscopy (TDS). TDS is a method of observing desorbed molecules from a sample surface during the increase of\ntemperature of the sample. The aim of this study was to determine optimum conditions:\ntemperature and time, to achieve clean surfaces in the shortest time. Available at various institutes of the ASCR
Thermal desorption spectroscopy in prototype furnace for chemical vapor deposition

Cleaning of the sample surfaces is crucial for scanning electron microscopy, especially for\nlow energy electron microscopy or for the deposition of thin layers, such as graphene,\nwhere surface has ...

Průcha, Lukáš; Daniel, Benjamin; Piňos, Jakub; Mikmeková, Eliška
Ústav přístrojové techniky, 2018

Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer
Zouhar, Martin; Radlička, Tomáš; Oral, Martin; Konvalina, Ivo
2018 - English
The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials with tailored functionality for next-generation electronic devices, the investigation\nof the IMFP is still topical and of high importance. This is true especially at low energies, landing energy of electrons below 100 eV, that are hard to study using well established\ntechniques of electron spectroscopy. Available at various institutes of the ASCR
Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer

The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials ...

Zouhar, Martin; Radlička, Tomáš; Oral, Martin; Konvalina, Ivo
Ústav přístrojové techniky, 2018

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