Optimization of the outflow regime in Římov reservoir from the point of view of water supply
Mercado, Ma. Cristina Paule; Hejzlar, Josef; Jarošík, Jiří; Porcal, Petr
2023 - English The best management strategy for the Římov reservoir: (a) discharge from a depth of 3–5 m during the stratified season, (b) without support for SHP and with high reservoir filling, (c) reducing the phosphorus loading of the reservoir as much as possible. The impacts of climate change on water quality are significant, as inflow DOC and P concentrations here increase with temperature and flow variability. The effects of climate change can be mitigated by targeted management of the reservoir, but the quality of water inflow will still deteriorate further. Keywords: water; dissolved organic matter; reservoir Available at various institutes of the ASCR Optimization of the outflow regime in Římov reservoir from the point of view of water supply

The best management strategy for the Římov reservoir: (a) discharge from a depth of 3–5 m during the stratified season, (b) without support for SHP and with high reservoir filling, (c) reducing the ...

Mercado, Ma. Cristina Paule; Hejzlar, Josef; Jarošík, Jiří; Porcal, Petr
Biologické centrum, 2023

Programs and Algorithms of Numerical Mathematics 21 : Jablonec nad Nisou, June 19-24, 2022 : Proceedings of Seminar
Chleboun, J.; Kůs, Pavel; Papež, Jan; Rozložník, Miroslav; Segeth, Karel; Šístek, Jakub
2023 - English These proceedings contain peer-reviewed papers that are based on the invited lectures, short communications, and posters presented at the 21st seminar Programs and Algorithms of Numerical Mathematics (PANM) held in Merkur Hotel, Jablonec nad Nisou, Czech Republic, June 19-24, 2022.\nThe seminar was organized by the Institute of Mathematics of the Czech Academy of Sciences under the auspices of EU-MATHS-IN.CZ, Czech Network for Mathematics in Industry, and with the nancial support provided by the RSJ Foundation. It continued the previous seminars on mathematical software and numerical methods held (biennially, with only one exception) in Alšovice, Bratříkov, Janov nad Nisou, Kořenov, Lázně Libverda, Dolní Maxov, Prague, and Hejnice in the period 1983-2020. The objective of this series of seminars is to provide a forum for presenting and discussing advanced topics in numerical analysis, computer implementation of numerical algorithms, new approaches to mathematical modeling, and single- or multi-processor applications of computational methods. Keywords: numerical mathematics Available in digital repository of the ASCR Programs and Algorithms of Numerical Mathematics 21 : Jablonec nad Nisou, June 19-24, 2022 : Proceedings of Seminar

These proceedings contain peer-reviewed papers that are based on the invited lectures, short communications, and posters presented at the 21st seminar Programs and Algorithms of Numerical Mathematics ...

Chleboun, J.; Kůs, Pavel; Papež, Jan; Rozložník, Miroslav; Segeth, Karel; Šístek, Jakub
Matematický ústav, 2023

Statistical Method Selection Matters: Vanilla Methods in Regression May Yield Misleading Results
Kalina, Jan
2023 - English The primary aim of this work is to illustrate the importance of the choice of the appropriate methods for the statistical analysis of economic data. Typically, there exist several alternative versions of common statistical methods for every statistical modeling task\nand the most habitually used (“vanilla”) versions may yield rather misleading results in nonstandard situations. Linear regression is considered here as the most fundamental econometric model. First, the analysis of a world tourism dataset is presented, where the number of international arrivals is modeled for 140 countries of the world as a response of 14 pillars (indicators) of the Travel and Tourism Competitiveness Index. Heteroscedasticity is clearly recognized in the dataset. However, the Aitken estimator, which would be the standard remedy in such a situation, is revealed here to be very inappropriate. Regression quantiles represent a much more suitable solution here. The second illustration with artificial data reveals standard regression quantiles to be unsuitable for data contaminated by outlying values. Their recently proposed robust version turns out to be much more appropriate. Both\nillustrations reveal that choosing suitable methods represent an important (and often difficult) part of the analysis of economic data. Keywords: linear regression; assumptions; non-standard situations; robustness; diagnostics Fulltext is available at external website. Statistical Method Selection Matters: Vanilla Methods in Regression May Yield Misleading Results

The primary aim of this work is to illustrate the importance of the choice of the appropriate methods for the statistical analysis of economic data. Typically, there exist several alternative versions ...

Kalina, Jan
Ústav teorie informace a automatizace, 2023

A new blade cascade for flutter studies
Šnábl, Pavel; Pešek, Luděk; Procházka, Pavel P.; Skála, V.
2023 - English In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major construction improvements over the original cascade which now allow more precise and reliable measurements. The stability of the new blade cascade with five NACA 0010 profiles with rotational degree of freedom is assessed by Travelling Wave Mode approach and Aerodynamic Influence Coefficient approach. Keywords: blade cascade; stability; travelling wave mode; aerodynamic influence coefficient Available at various institutes of the ASCR A new blade cascade for flutter studies

In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major ...

Šnábl, Pavel; Pešek, Luděk; Procházka, Pavel P.; Skála, V.
Ústav termomechaniky, 2023

Kráľova Lehota. Paleomagnetic research. Report
Elbra, Tiiu; Schnabl, Petr; Aidona, E.; Kdýr, Šimon; Uçar, Hakan; Pruner, Petr; Benediková, L.
2023 - English Keywords: Archeological artefact; paleomagnetic dating; rock magnetism Available at various institutes of the ASCR Kráľova Lehota. Paleomagnetic research. Report

Elbra, Tiiu; Schnabl, Petr; Aidona, E.; Kdýr, Šimon; Uçar, Hakan; Pruner, Petr; Benediková, L.
Geologický ústav, 2023

PHYSICOCHEMICAL CHARACTERISTICS AND EVOLUTION OF AEROSOL FROM OPEN COMBUSTION OF BIOMASS DURING THE TRADITIONAL “BURNING OF THE WITCHES”
Mbengue, Saliou; Vodička, Petr; Komínková, Kateřina; Schwarz, Jaroslav; Zíková, Naděžda; Vítková, Gabriela; Windell, Laurence Christian; Suchánková, Lenka; Lhotka, Radek; Julaha, Kajal; Prokeš, Roman; Šmejkalová Holubová, A.; Ondráček, Jakub; Ždímal, Vladimír; Holoubek, Ivan
2023 - English Open biomass burning (OBB) is a major source releasing large quantities of gaseous and particulate pollutants into the atmosphere, with global, regional and local impacts on air quality, public health and climate (Andreae, 2019, Chen et al., 2017). OBB aerosols mainly consist of carbonaceous matter, and a considerable amount of inorganic salts, which present distinctly different optical properties (Chen et al., 2017, Reid et al., 2005). In this study, we investigate the influence of OBB during the traditional Burning of the Witches (BoW), referred to in Czech as “Pálení čarodějnic”, on the physico-chemical properties of atmospheric aerosols collected at the National Atmospheric Observatory Košetice (NAOK). The BoW is a centuries-old pagan tradition very popular in the Czech Republic. Today, it is celebrated during the night from April 30 to May 1 by lighting bonfires made of woodpiles with fake witches. Keywords: biomass burning; air pollution; size distribution; atmospheric ageing Available in digital repository of the ASCR PHYSICOCHEMICAL CHARACTERISTICS AND EVOLUTION OF AEROSOL FROM OPEN COMBUSTION OF BIOMASS DURING THE TRADITIONAL “BURNING OF THE WITCHES”

Open biomass burning (OBB) is a major source releasing large quantities of gaseous and particulate pollutants into the atmosphere, with global, regional and local impacts on air quality, public health ...

Mbengue, Saliou; Vodička, Petr; Komínková, Kateřina; Schwarz, Jaroslav; Zíková, Naděžda; Vítková, Gabriela; Windell, Laurence Christian; Suchánková, Lenka; Lhotka, Radek; Julaha, Kajal; Prokeš, Roman; Šmejkalová Holubová, A.; Ondráček, Jakub; Ždímal, Vladimír; Holoubek, Ivan
Ústav výzkumu globální změny , 2023

PM1 UNDER THE MICROSCOPE: MULTI-ANNUAL AEROSOL OPTICAL PROPERTIES AND SIZE DISTIRBUTION OBSERVATION AT PERI-URBAN ATMOSPHERIC SITE ATOLL
Suchánková, Lenka; Bourrianne, E.; De Fillipi, R.; De Brito, J. F.; Riffault, V.; Prokeš, Roman; Holoubek, Ivan; Ždímal, V.; Crumeyrolle, S.
2023 - English Atmospheric aerosols (AA) belong to short-lived climate forcers with high spatial and temporal variability. Although the radiative effects of AA are greatest on regional scales, changes in aerosol emissions can induce long-term global climate effects (Szopa et al., 2021). Thus, the measurement of aerosol properties is essential for better understanding of aerosol’s impact on health and climate. Although several international projects and platforms have been monitoring AA properties worldwide (GAW, WMO, ACTRIS, EMEP, EUCAARI, etc., Pandolfi et al., 2018), only PM10 or PM2.5 cutoff sizes have been used for measurements, and information about PM1 particles is missing. \nThe aim of this study is to present aerosol scattering properties with supporting data of absorption and particle number size distribution in PM1 in years 2018-2022 at peri-urban atmospheric site “Atmospheric Observations in LiLLE (ATOLL) in Lille, France. This study is the first to present results dedicated to aerosol scattering properties at this site. Keywords: pm1; scattering coefficient; nephelometer; fossil fuel and biomass burning contribution; aethalometer; smps Available in digital repository of the ASCR PM1 UNDER THE MICROSCOPE: MULTI-ANNUAL AEROSOL OPTICAL PROPERTIES AND SIZE DISTIRBUTION OBSERVATION AT PERI-URBAN ATMOSPHERIC SITE ATOLL

Atmospheric aerosols (AA) belong to short-lived climate forcers with high spatial and temporal variability. Although the radiative effects of AA are greatest on regional scales, changes in aerosol ...

Suchánková, Lenka; Bourrianne, E.; De Fillipi, R.; De Brito, J. F.; Riffault, V.; Prokeš, Roman; Holoubek, Ivan; Ždímal, V.; Crumeyrolle, S.
Ústav výzkumu globální změny , 2023

Thermal and creep analysis of VVER-1000 reactor pressure vessel at high temperatures caused by fuel melting during severe accident
Gabriel, Dušan; Gál, P.; Kotouč, M.; Dymáček, Petr; Masák, Jan; Kopačka, Ján
2023 - English Thermal and creep analysis of the VVER-1000 reactor pressure vessel (RPV) was performed at high temperatures caused by fuel melting during severe accident. First, the integral code ASTEC was applied simulating severe accident evolution since an initiating event up to a hypothetical radioactive release into the environment. The ASTEC outputs including the remaining RPV wall thickness, the heat flux achieved and the temperature profile in the ablated vessel wall served as boundary conditions for the consequent assessment of RPV integrity carried out with the aid of finite element method (FEM). The FEM analysis was performed including the creep behaviour of RPV material using a complex creep probabilistic exponential model with damage. The objective of the analysis was to computationally assess emergency condition and, on this basis, to propose a general methodology for evaluating the integrity of RPV at high temperatures due to fuel melting during severe accident. Keywords: integrity of reactor pressure vessel; severe accident; ASTEC; creep; FEM Fulltext is available at external website. Thermal and creep analysis of VVER-1000 reactor pressure vessel at high temperatures caused by fuel melting during severe accident

Thermal and creep analysis of the VVER-1000 reactor pressure vessel (RPV) was performed at high temperatures caused by fuel melting during severe accident. First, the integral code ASTEC was applied ...

Gabriel, Dušan; Gál, P.; Kotouč, M.; Dymáček, Petr; Masák, Jan; Kopačka, Ján
Ústav termomechaniky, 2023

Reduced modelling of aeroelastic instability in a turbine blade cascade
Pešek, Luděk; Šnábl, Pavel; Prasad, Chandra Shekhar
2023 - English The contribution deals with the first results on flutter instability of the linear cascade triggered by impulse excitation. Together with experimental results, numerical results obtained by reduced modelling of the cascade using van der Pol model of self-excitation are presented and discussed. Keywords: flutter; blade cascade; self-excitation; Van der Pol Available at various institutes of the ASCR Reduced modelling of aeroelastic instability in a turbine blade cascade

The contribution deals with the first results on flutter instability of the linear cascade triggered by impulse excitation. Together with experimental results, numerical results obtained by reduced ...

Pešek, Luděk; Šnábl, Pavel; Prasad, Chandra Shekhar
Ústav termomechaniky, 2023

Simulation of heterogeneously-catalyzed non-isothermal reactive flow in industrial packed beds
Hlavatý, Tomáš; Isoz, Martin; Khýr, M.
2023 - English Packed bed reactors are the most frequently used devices to perform heterogeneously catalyzed reactions on industrial scales. An industrial real-life heterogeneous catalysis is complex process that combines fully three-dimensional mass, momentum and energy transport on several scales. In the present work, we leverage our previously developed CFD solver for non-isothermal heterogeneously catalyzed reactive flow based on the finite volume method and couple it with our\nin-house DEM-based method for preparation of random packed beds. The resulting framework is verified in the simplified cases against available analytical solutions and correlations and is used to study an industrially-relevant case of ethylene oxychlorination performed in a tubular packed bed comprising CuCl2-coated catalyst carrying particles. In particular, we compare properties of three different industrially used catalyst carrying particles: Raschig rings, Reformax, and Wagon wheels Keywords: CFD; OpenFOAM; non-isothermal flow Available in a digital repository NRGL Simulation of heterogeneously-catalyzed non-isothermal reactive flow in industrial packed beds

Packed bed reactors are the most frequently used devices to perform heterogeneously catalyzed reactions on industrial scales. An industrial real-life heterogeneous catalysis is complex process that ...

Hlavatý, Tomáš; Isoz, Martin; Khýr, M.
Ústav termomechaniky, 2023