National Repository of Grey Literature 146 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Optimized design of reinforcement of concrete cross section
Hudyma, Nazar ; Laníková, Ivana (referee) ; Štěpánek, Petr (advisor)
The subject of this thesis is the optimization of design variables of reinforced concrete cross-section, especially its reinforcement. To solve this problem, it was first necessary to elaborate a search section that discusses various methods and approaches for solving the problem. The research part also includes processing and evaluation of tasks solved by other authors in available literature. For the optimization task, in the following parts both the general formulation and the detailed formulation of the partial parts of the concrete reinforcement structure optimization process are processed. As an example of optimization, a simple beam is chosen, which is subjected to bending moment and normal force one load case, where the example will be divided according to the formulation of both the function and the vector of unknown parameters (variables) defining the exact shape and properties of the reinforced concrete section. The examples will then be tested with regard to the speed of convergence and the degree of deviation between the best solutions found for each optimization algorithm used. At the end there will be a comparison and evaluation of the solution of the given task, as well as a summary of the whole bachelor thesis with reference to another possible direction in the optimization problems focused on reinforced concrete structures. In the appendices there will be a solution of selected examples.
DYNAMICS OF WINTER SEVERITY AND ITS EFFECT ON RECREATION
Zahradníček, Pavel ; Rožnovský, J. ; Brzezina, J. ; Štěpánek, Petr ; Farda, Aleš ; Chuchma, F.
Air temperature in winter months and colder half-year is an important factor for wide range of human activities, including recreation. As a result of current climate change, average air temperatures increase in winter as well. This, however, does not mean that there are no frosts. Each winter season can be assessed using several parameters. In this paper we used the sum of effective air temperatures below 0 degrees C and- 5 degrees C. Absolute minimum air temperature was used as an indicator of the extremity of a particular period. Space-time analysis has been performed for both parameters. Air temperatures in winter months are to a large extent influenced by the continentality of the climate. In general, the temperatures in Bohemia rise faster compared to Moravia and the absolute lowest minimum air temperatures are observed in the Western parts of the country. Based on a multiparametric analysis of climate characteristics, the coldest winter and colder half-year was in 1963, in contrast, the mildest winter was in 2007.
Summary report for providing meteorological forecasts for CEPS company
Farda, Aleš ; Štěpánek, Petr ; Meitner, Jan ; Zahradníček, Pavel
Global Change Research Institute CAS provides CEPS company with outputs from numerical weather prediction (NWP) models. The cooperation lasts from 2015 up to now. Selected fields of meteorological variables (namely solar radiation - global and direct, and air temperature in 2 m) are processed from grib files into suitable spatial information, like administrative districts (areal averages) or position of grid points of GFS model. NPW models used are ALADIN from Czech Hydrometeorological Institute and GFS model (from NCEP, NOAA). Outputs are provided for several days ahead, and are issued each morning.
Regional yield forecasting for improved decision making in the plant production
Trnka, Miroslav ; Hlavinka, Petr ; Kudláčková, Lucie ; Balek, Jan ; Meitner, Jan ; Možný, Martin ; Štěpánek, Petr ; Bartošová, Lenka ; Semerádová, Daniela ; Bláhová, Monika ; Lukas, Vojtěch ; Žalud, Zdeněk
The methodology describes how to predict yields of key crops, and at the same time addresses reliability of the predictions and how these can be used. The ability to predict yield levels more than 2 months prior the harvest on the level of regions (NUTS3¨) and districts (LAU1) brings also new opportunities to mitigate impacts of adverse conditions. The methodology shows that the yield forecasts and yield anomalies in particular are consistent and usable in practices. In this methodology, the results of 2018 yield forecasts are presented as an example. The yield forecasting system for the Czech Republic is fully functional and is and will be available through www.vynosy-plodin.cz.
Strengthening reinforced concrete column confined by FRP fabric
Kostiha, Vojtěch ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Bilčík,, Juraj (referee) ; Štěpánek, Petr (advisor)
The doctoral thesis deals with the strengthening of reinforced concrete columns by FRP fabric wrapping. Its aim is to describe the principles of confinement based on the analytical study, numerical simulations and the results of the experimental program. The description of the confinement philosophy is made with respect to the type of FRP material used. It was therefore possible to present a design process of confinement, which accurately predicts the behaviour of the confined columns. At the same time, some effects limiting the effect of confinement (e.g. the method of wrapping, the number of FRP fabric layers, the slenderness of the element, etc.) are included in the design. The dissertation also presents basic information about FRP material and its properties and gives an overview of design approaches of the FRP confined columns. The dissertation also pointing out the shortcomings of the design code ČSN EN 1992-1-1. The stated example highlights the significant variation in properties of confined concrete determined by selected approaches. This variation of properties complicates the design of this strengthening method. The experimental program was used to verify the basic principles of confinement and, through high columns, allowed a description of the behaviour in almost the whole range of interaction diagram. The conclusions of the work provide information on possible future research direction.
2-Oxazoline triblock copolymers with hydrophilic, lipophilic and fluorophilic blocks: from synthesis to hierarchical self-assembly
Kaberov, Leonid ; Štěpánek, Petr (advisor) ; Černoch, Peter (referee) ; Schlaad, Helmut (referee)
DOCTORAL THESIS ABSTRACT 2-Oxazoline triblock copolymers with hydrophilic, lipophilic and fluorophilic blocks: from synthesis to hierarchical self-assembly MSc. Leonid Kaberov The focus of this research was on the study of di- and triblock poly(2-oxazoline) copolymers with fluorinated blocks. The synthesis and solution properties of novel copolymers combining hydrophilic, hydrophobic (lipophilic) and fluorophilic moieties into one segmented molecule were reported. The simple synthetic approach which provides an easy way to attach a CnF2n+1 terminal chain to a poly(2-methyl-2-oxazoline)-block-poly(2-n-octyl-2-oxazoline) copolymer was described. Small-angle neutron and x-ray scattering experiments unambiguously proved the existence of polymersomes, worm-like micelles and their aggregates in aqueous solution. It was shown that increasing content of fluorine in the poly(2-oxazoline) copolymers results in a morphological transition from bilayered or multi-layered vesicles to worm-like micelles. The synthesis of poly(2-perfluoroalkyl-2-oxazoline)s is complicated by their extremely low activity in cationic ring-opening polymerization reaction (CROP), both in the initiation and in the propagation due to strong electron-withdrawing effect of perfluoroalkyl substituent. A detailed systematic study on synthetic...
Functionalized hybrid polymer structures for biomedical applications
Rabyk, Mariia ; Štěpánek, Petr (advisor) ; Sedláková, Zdeňka (referee) ; Kotek, Jan (referee)
This doctoral thesis is dedicated to the synthesis and characterization of novel functionalized hybrid structures for biomedical purposes. Systems reported in this work can be subdivided into the two main groups: natural-based materials and synthetic amphiphilic block copolymers. Both groups were studied as perspective theranostic agents for medical applications. In the first group, natural polysaccharides glycogen and mannan were selected as starting materials for preparation of novel nanoconjugates that possess ability for multimodal detection in vivo. Because grafting of natural macromolecules with synthetic polymers generally slows down the biodegradation rate, both polysaccharides were modified in two different ways to form nanoprobes with or without poly(2-methyl-2-oxazoline)s chains. The prepared nanoconjugates were functionalized with N-hydroxysuccinimide-activated fluorescence and magnetic resonance imaging labels. The resulting materials were tested both in vitro and in vivo and were shown to be completely biocompatible, biodegradable and exhibit some extra benefits in terms of their practical usage in biomedicine. Glycogen was functionalized with allyl and propargyl groups with following freeze-drying from aqueous solutions to form nano- and microfibrous materials. The presence of both...
Synthesis, organization and dynamic behaviour in poly(p-octylstyrene)-b-poly(butyl methacrylate) block copolymer systems
Černoch, Peter ; Štěpánek, Petr (advisor) ; Sedlák, Marián (referee) ; Hlaváček, Bořivoj (referee) ; Tuzar, Zdeněk (referee)
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System for monitoring and forecast of impacts of agricultural drought
Trnka, Miroslav ; Štěpánek, Petr ; Chuchma, F. ; Možný, M. ; Bartošová, Lenka ; Hlavinka, Petr ; Balek, Jan ; Zahradníček, Pavel ; Skalák, Petr ; Farda, Aleš ; Semerádová, Daniela ; Meitner, Jan ; Bláhová, M. ; Fiala, R. ; Žalud, Zdeněk
The methodology describes how to predict soil moisture and drought intensity, and at the same time addresses reliability of the predictions and how these can be used. The ability to predict soil moisture values over a period of up to 9 days is presented through using ensemble of models for numerical weather forecasts. This method brings also new opportunities to mitigate impacts during drought events by farmers using such forecasting tools. With regard to the relatively high predictability of soil moisture and drought intensity, the methodology introduces the basic procedures and provides necessary information for the users. In this methodology, the results of 2017 drought event are presented as an example. The drought forecasting system for the Czech Republic is fully functional and is and will be available through www.intersucho.cz.
Forest regeneration within the treeline ecotone in the Giant Mountains under climate change
Cudlín, Ondřej ; Chumanová-Vávrová, Eva ; Edwards-Jonášová, Magda ; Heřman, Michal ; Štěpánek, Petr ; Cudlín, Pavel
Natural regeneration of mountain spruce forests began in the Giant Mountains 25 years ago after a reduction\nof severe and long-enduring air pollution. This process has been influenced by climatic change.\nThe aim of our contribution was to present background data for the potential elevational shift of spruce\nregeneration under conditions of climate change. These upslope shifts may also depend on constraints\nsuch as climate extremes, unfavourable soil conditions, absence of ectomycorrhizal symbionts, and lack of\nmicrosites suitable for seedlings. Since 2014, we have studied the main driving factors affecting Norway\nspruce regeneration, and in particular soil conditions, ectomycorrhizal symbionts, ground vegetation cover,\nand forest health, in six transects across the treeline ecotone located on a NW-to-NE transect through\nthe Giant Mountains. Microclimatic measurements showed that the mean difference in growing season\ntemperature between the montane spruce forests and forests at the treeline was −0.54°C. The model\nHADGEM2 predicted that in 20 years the temperature at the treeline will be similar to the current one at\nmontane elevations. The difference in prevailing soil types between the montane spruce forests and forests\nat the current treeline (i.e. podzol vs. ranker type) could be an important factor limiting success of the\nupslope spreading of spruce. Furthermore, areas covered by microsites favourable for natural spruce regeneration,\nespecially spruce litter patches, decaying wood, mosses, and Avenella flexuosa stands, were\nshown to decrease with increasing elevation. It is likely that spruce will move upslope in response to climate\nchange, but the process is likely to be slow or even blocked for some periods, especially by unfavourable\nsoil conditions and climatic extremes.

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See also: similar author names
1 Štěpánek, P.
1 Štěpánek, Pavel
1 Štěpánek, Přemysl
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