Number of found documents: 11513
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Relation between optical and microscopic properties of hydrogenated silicon thin films with integrated germanium and tin nanoparticles
Stuchlík, Jiří; Stuchlíková, The-Ha; Čermák, Jan; Kupčík, Jaroslav; Fajgar, R.; Remeš, Zdeněk
2019 - English
The hydrogenated amorphous silicon layers (a-Si:H) were deposited by PECVD method on quartz substrates. During interruption of PECVD process the vacuum chamber was pumped up to 10-5 Pa and 1 nm thin films of Germanium or Tin were evaporated on the surface. The materials form isolated nanoparticles (NPs) on the a-Si:H surface. Then the deposited NPs were covered and stabilized by a-Si:H layer by PECVD. Those two deposition processes were alternated 5 times. The a-Si:H thin films with integrated Ge or Sn NPs were characterized optically by PDS and CPM methods, and microscopically by SEM and AFM microscopies. Optical and microscopic properties of the structures are correlated and discussed considering their application in photovoltaics.\n Keywords: thin films; a-Si:H; nanoparticles; germanium; tin Available at various institutes of the ASCR
Relation between optical and microscopic properties of hydrogenated silicon thin films with integrated germanium and tin nanoparticles

The hydrogenated amorphous silicon layers (a-Si:H) were deposited by PECVD method on quartz substrates. During interruption of PECVD process the vacuum chamber was pumped up to 10-5 Pa and 1 nm thin ...

Stuchlík, Jiří; Stuchlíková, The-Ha; Čermák, Jan; Kupčík, Jaroslav; Fajgar, R.; Remeš, Zdeněk
Fyzikální ústav, 2019

Příčina mechanického chvění těžních synchronních motorů Palašer a jeho odstranění
Pavelka, J.; Šimek, J.; Kobrle, P.; Kokeš, Petr
2019 - Czech
Příspěvek popisuje postup a výsledek analýzy mechanického rozkmitávání těžních strojů na dole Palašer v Ruské federaci. Jako příčina byla určena změna velikosti magnetického toku ve vzduchové mezeře vlivem drážkování statorů. Provedené simulace prokázaly možnost odstranění změny magnetického toku injektáží vhodných napětí statorového vinutí. V dalším je popsána realizace této injektáže pomocí přímovazební kompenzace střídavé složky momentu. Na závěr jsou uvedeny oscilografické záznamy před a po injektáži. The paper describes the procedure and the result of analysis of mechanical vibrations of mining machines at the Palašer mine in the Russian Federation. The cause of these vibrations was the change in the magnitude of the magnetic flux in the air gap. The simulations showed the possibility of eliminating these changes in\nmagnetic flux by injecting suitable voltages into the stator windings. The implementation of this injection is further described by torque variable component feed-direct compensation. Finally, oscillography records are presented before and after injection. Keywords: mining machine; synchronous motor; indirect frequency converter; Maxwell force; resonant frequency; feed-direct compensation; injected voltage Available at various institutes of the ASCR
Příčina mechanického chvění těžních synchronních motorů Palašer a jeho odstranění

Příspěvek popisuje postup a výsledek analýzy mechanického rozkmitávání těžních strojů na dole Palašer v Ruské federaci. Jako příčina byla určena změna velikosti magnetického toku ve vzduchové mezeře ...

Pavelka, J.; Šimek, J.; Kobrle, P.; Kokeš, Petr
Ústav termomechaniky, 2019

Residual stresses of laser-welded pressure vessel steel determined by X-ray and neutron diffraction
Trojan, K.; Vlk, A.; Čapek, J.; Hervoches, Charles; Ganev, N.
2019 - English
To gain insight into the quality of the laser weld, information about the residual stress state across the weld is very useful. In this contribution, the residual stress profiles for lowalloy carbon steel plates of P355NL1 grade, which were laser welded from both sides, are presented. To separate the effects of the production of plates from the welding process, the samples were annealed for stress relieving. Using X-ray and neutron diffraction, the surface and bulk RS profiles were obtained. From the obtained data, first, the difference in the character of the longitudinal (parallel to the weld axis) and the transversal component of the RS tensor can be seen. The longitudinal component has a tensile character with a maximum value approximately 500 MPa. Values and character of the transversal component vary strongly with depth and distance from the weld axis. Keywords: nondestructive examination; ferromagnetic materials; residual stresses Available at various institutes of the ASCR
Residual stresses of laser-welded pressure vessel steel determined by X-ray and neutron diffraction

To gain insight into the quality of the laser weld, information about the residual stress state across the weld is very useful. In this contribution, the residual stress profiles for lowalloy carbon ...

Trojan, K.; Vlk, A.; Čapek, J.; Hervoches, Charles; Ganev, N.
Ústav jaderné fyziky, 2019

Lexicalized Syntactic Analysis by Restarting Automata
Mráz, F.; Otto, F.; Pardubská, D.; Plátek, Martin
2019 - English
We study h-lexicalized two-way restarting automata that can rewrite at most i times per cycle for some i ≥ 1 (hRLWW(i)-automata). This model is considered useful for the study of lexical (syntactic) disambiguation, which is a concept from linguistics. It is based on certain reduction patterns. We study lexical disambiguation through the formal notion of h-lexicalized syntactic analysis (hLSA). The hLSA is composed of a basic language and the corresponding h-proper language, which is obtained from the basic language by mapping all basic symbols to input symbols. We stress the sensitivity of hLSA by hRLWW(i)-automata to the size of their windows, the number of possible rewrites per cycle, and the degree of (non-)monotonicity. We introduce the concepts of contextually transparent languages (CTL) and contextually transparent lexicalized analyses based on very special reduction patterns, and we present two-dimensional hierarchies of their subclasses based on the size of windows and on the degree of synchronization. The bottoms of these hierarchies correspond to the context-free languages. CTL creates a proper subclass of context-sensitive languages with syntactically natural properties. Keywords: Restarting automaton; h-lexicalization; lexical disambiguation Fulltext is available at external website.
Lexicalized Syntactic Analysis by Restarting Automata

We study h-lexicalized two-way restarting automata that can rewrite at most i times per cycle for some i ≥ 1 (hRLWW(i)-automata). This model is considered useful for the study of lexical (syntactic) ...

Mráz, F.; Otto, F.; Pardubská, D.; Plátek, Martin
Ústav informatiky, 2019

Second Order Optimality in Markov and Semi-Markov Decision Processes
Sladký, Karel
2019 - English
Semi-Markov decision processes can be considered as an extension of discrete- and continuous-time Markov reward models. Unfortunately, traditional optimality criteria as long-run average reward per time may be quite insufficient to characterize the problem from the point of a decision maker. To this end it may be preferable if not necessary to select more sophisticated criteria that also reflect variability-risk features of the problem. Perhaps the best known approaches stem from the classical work of Markowitz on mean-variance selection rules, i.e. we optimize the weighted sum of average or total reward and its variance. Such approach has been already studied for very special classes of semi-Markov decision processes, in particular, for Markov decision processes in discrete - and continuous-time setting. In this note these approaches are summarized and possible extensions to the wider class of semi-Markov decision processes is discussed. Attention is mostly restricted to uncontrolled models in which the chain is aperiodic and contains a single class of recurrent states. Considering finite time horizons, explicit formulas for the first and second moments of total reward as well as for the corresponding variance are produced. Keywords: semi-Markov processes with rewards; discrete and continuous-time Markov reward chains; risk-sensitive optimality; average reward and variance over time Fulltext is available at external website.
Second Order Optimality in Markov and Semi-Markov Decision Processes

Semi-Markov decision processes can be considered as an extension of discrete- and continuous-time Markov reward models. Unfortunately, traditional optimality criteria as long-run average reward per ...

Sladký, Karel
Ústav teorie informace a automatizace, 2019

Mean-Risk Optimization Problem via Scalarization, Stochastic Dominance, Empirical Estimates
Kaňková, Vlasta
2019 - English
Many economic and financial situations depend simultaneously on a random element and on a decision parameter. Mostly it is possible to influence the above mentioned situation by an optimization model depending on a probability measure. We focus on a special case of one-stage two objective stochastic “Mean-Risk problem”. Of course to determine optimal solution simultaneously with respect to the both criteria is mostly impossible. Consequently, it is necessary to employ some approaches. A few of them are known (from the literature), however two of them are very important: first of them is based on a scalarizing technique and the second one is based on the stochastic dominance. First approach has been suggested (in special case) by Markowitz, the second approach is based on the second order stochastic dominance. The last approach corresponds (under some assumptions) to partial order in the set of the utility functions.\nThe aim of the contribution is to deal with the both main above mentioned approaches. First, we repeat their properties and further we try to suggest possibility to improve the both values simultaneously with respect to the both criteria. However, we focus mainly on the case when probability characteristics has to be estimated on the data base. Keywords: Two-objective stochastic optimization problems; scalarization; stochastic dominance; empirical estimates Fulltext is available at external website.
Mean-Risk Optimization Problem via Scalarization, Stochastic Dominance, Empirical Estimates

Many economic and financial situations depend simultaneously on a random element and on a decision parameter. Mostly it is possible to influence the above mentioned situation by an optimization model ...

Kaňková, Vlasta
Ústav teorie informace a automatizace, 2019

Utilization of Convolution Neural Network Based Road Detection in Mobile Robot Localization
Krejsa, Jiří; Věchet, Stanislav
2019 - English
Mobile robot on-road navigation requires fusion of both global and local sensory information with an emphasis on the road detection processing. The paper deals with the road detection based on convolution neural networks (CNN) using commonly available tools such as TensorFlow and Keras. The road is defined by its linear boundaries. Network output is formed by the road definition together with classification parameters and serves as a local sensor in Kalman filter based localization. CNN based road detection is currently capable to successfully detect about 90% of images. Keywords: convolution neural network; localization; road detection Available at various institutes of the ASCR
Utilization of Convolution Neural Network Based Road Detection in Mobile Robot Localization

Mobile robot on-road navigation requires fusion of both global and local sensory information with an emphasis on the road detection processing. The paper deals with the road detection based on ...

Krejsa, Jiří; Věchet, Stanislav
Ústav termomechaniky, 2019

Microscopic study of multifunctional drug molecule adhesion to electronic biosensors coated with diamond and gold nanoparticles
Finsterle, T.; Pilarčíková, I.; Bláhová, I.A.; Potocký, Štěpán; Kromka, Alexander; Ukraintsev, Egor; Nepovimová, E.; Musílek, K.; Kuča, K.; Rezek, B.
2019 - English
The easy and fast detection of drug content and concentration levels is demanded in biological research as well as in clinical practice. Here we study on microscopic level how nanodiamonds and gold nanoparticles interact with a multifunctional drug molecule directly on a biosensor surface. The sensors are made of interdigitated Au electrodes coated by 5 nm hydrogenated or oxidized nanodiamonds and further combined with Au colloidal nanoparticles (size 20 nm) providing nanoscale composite (spacing 100 nm). Atomic force microscopy is employed to measure local tip-surface adhesion forces and surface topography. AFM adhesion maps show that the drug binds to all types of nanoparticles and the adhesion is also significantly influenced by the substrates on which the nanoparticles are deposited. Role of local AFM tip interaction with nanostructured surface is also discussed.\n Keywords: alzheimer drugs; biosensors; nanodiamonds; nanoparticles Fulltext is available at external website.
Microscopic study of multifunctional drug molecule adhesion to electronic biosensors coated with diamond and gold nanoparticles

The easy and fast detection of drug content and concentration levels is demanded in biological research as well as in clinical practice. Here we study on microscopic level how nanodiamonds and gold ...

Finsterle, T.; Pilarčíková, I.; Bláhová, I.A.; Potocký, Štěpán; Kromka, Alexander; Ukraintsev, Egor; Nepovimová, E.; Musílek, K.; Kuča, K.; Rezek, B.
Fyzikální ústav, 2019

Real-time diagnostics for ROS running systems based on probabilistic patterns identification
Věchet, Stanislav; Krejsa, Jiří
2019 - English
Autonomous mobile robots consists of various software modules to achieve given goal, including solving complex navigation tasks as localization, mapping or path planning. These tasks are highly dependent on the quality of data measured and gathered from hardware subsystems. Using Robot Operating System (ROS) as integration basis reduces the development effort and time to market. While ROS framework itself is considered as reliable and stable to run even soft real-time tasks, in case of any internal failures on data misreadings can be problematic to debug or even identify the problem for common user. Due to this unpleasant situations we develop a virtual assistant, internally represented as diagnostic expert system, to help users to identify and possibly fix the problem. Keywords: diagnostic expert system; bayesian network; system diagnostic Available at various institutes of the ASCR
Real-time diagnostics for ROS running systems based on probabilistic patterns identification

Autonomous mobile robots consists of various software modules to achieve given goal, including solving complex navigation tasks as localization, mapping or path planning. These tasks are highly ...

Věchet, Stanislav; Krejsa, Jiří
Ústav termomechaniky, 2019

Finite element implementation of creep constitutive model including transient effects
Gabriel, Dušan; Masák, Jan; Plešek, Jiří; Kloc, Luboš; Dymáček, Petr
2019 - English
A complex creep constitutive model including transient effects was implemented in the finite element code PMD (Package for Machine Design). The material model for P-91-type creep-resistant steel together with computer implementation was verified by means of uniaxial stress loadings. Testing bar was discretized by the finite element method (FEM) and loaded with uniaxial stresses and constant temperatures that were used to demonstrate the analytical solutions in original paper. Keywords: creep; transient effects; FEM Available at various institutes of the ASCR
Finite element implementation of creep constitutive model including transient effects

A complex creep constitutive model including transient effects was implemented in the finite element code PMD (Package for Machine Design). The material model for P-91-type creep-resistant steel ...

Gabriel, Dušan; Masák, Jan; Plešek, Jiří; Kloc, Luboš; Dymáček, Petr
Ústav termomechaniky, 2019

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