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Misie a benediktinské začátky pražského biskupství
Sommer, Petr
2023 - český
Studie se věnuje v souvislosti s výročím 1050 let od založení pražského biskupství tématu první české diecéze a zasazuje ji do středoevropských souvislostí karolínské a otonské říše, souvisejících církevních institucí a christianizačních procesů. Formou sondy sleduje význam misie pro vznik pražského biskupství. V této souvislosti pojednává otázky spojené se sakrální architekturou, liturgickou výbavu a písemnou kulturo neoddělitelně spjatou s novou křesťanskou vzdělaností i s církevní správou. In the context of the 1050th anniversary of the founding of the Prague bishopric, the study focuses on the topic of the first Czech diocese and places it in the Central European context of the Carolingian and Ottonian empires, related ecclesiastical institutions and Christianization processes. In the form of a probe, it traces the importance of the mission for the establishment of the Prague bishopric. In this context, it discusses issues related to sacred architecture, liturgical equipment and written culture inseparably linked to the new Christian education and church administration.
Klíčová slova:
Christianity; Prague; Bishopric of Prague; Christianisation; hagiography; medieval Czech lands
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Misie a benediktinské začátky pražského biskupství
Studie se věnuje v souvislosti s výročím 1050 let od založení pražského biskupství tématu první české diecéze a zasazuje ji do středoevropských souvislostí karolínské a otonské říše, souvisejících ...
A new blade cascade for flutter studies
Šnábl, Pavel; Pešek, Luděk; Procházka, Pavel P.; Skála, V.
2023 - anglický
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.
Klíčová slova:
blade cascade; stability; travelling wave mode; aerodynamic influence coefficient
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 ...
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 - anglický
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.
Klíčová slova:
biomass burning; air pollution; size distribution; atmospheric ageing
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
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 ...
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 - anglický
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.
Klíčová slova:
pm1; scattering coefficient; nephelometer; fossil fuel and biomass burning contribution; aethalometer; smps
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
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 ...
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 - anglický
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.
Klíčová slova:
integrity of reactor pressure vessel; severe accident; ASTEC; creep; FEM
Dokument je dostupný na externích webových stránkách.
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 ...
Reduced modelling of aeroelastic instability in a turbine blade cascade
Pešek, Luděk; Šnábl, Pavel; Prasad, Chandra Shekhar
2023 - anglický
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.
Klíčová slova:
flutter; blade cascade; self-excitation; Van der Pol
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 ...
Simulation of heterogeneously-catalyzed non-isothermal reactive flow in industrial packed beds
Hlavatý, Tomáš; Isoz, Martin; Khýr, M.
2023 - anglický
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
Klíčová slova:
CFD; OpenFOAM; non-isothermal flow
Plné texty jsou dostupné v digitálním repozitáři NUŠL
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 ...
Numerical implementation of incremental minimization principle for materials with multiple rate-independent dissipative mechanisms
Frost, Miroslav; Moskovka, Alexej; Sedlák, Petr; Valdman, Jan
2023 - anglický
The incremental energy minimization approach is a compact variational formulation of the evolutionary boundary value problem for constitutive models of materials with a rate-independent response. Although it can be easily applied to many conventional models, its main advantages arise when applied to models with multiple strongly coupled dissipation mechanisms, where the direct construction of the coupled yield conditions and flow rules may be challenging. However, this usually requires a more complex numerical treatment of the resulting sequence of time-incremental boundary value problems resolved via the finite element method. This contribution presents, compares and discusses two genuine minimization approaches - the staggered solution procedure relying on alternating minimization and the monolithic approach employing global minimization - for an advanced constitutive model of shape memory alloys.
Klíčová slova:
variational approach; constitutive modeling; numerical implementation
Dokument je dostupný na externích webových stránkách.
Numerical implementation of incremental minimization principle for materials with multiple rate-independent dissipative mechanisms
The incremental energy minimization approach is a compact variational formulation of the evolutionary boundary value problem for constitutive models of materials with a rate-independent response. ...
Astrophysical black holes embedded in organized magnetic fields
Karas, Vladimír
2023 - anglický
Large-scale magnetic fields pervade the cosmic environment where the astrophysical black holes are often embedded and influenced by mutual interaction. In thiscontribution, we outline the appropriate mathematical framework to describe magnetized black holes within General Relativity, and we show several examples of how these can be employed in the astrophysical context. In particular, we examine the magnetized black hole metric in terms of an exact solution of electro-vacuum Einstein-Maxwell equations under the influence of a non-vanishing electric charge. New effects emerge: the expulsion of the magnetic flux out of the black-hole horizon depends on the intensity of the imposed magnetic field.
Klíčová slova:
black holes; electromagnetic fields; general relativity
Dokument je dostupný na externích webových stránkách.
Astrophysical black holes embedded in organized magnetic fields
Large-scale magnetic fields pervade the cosmic environment where the astrophysical black holes are often embedded and influenced by mutual interaction. In thiscontribution, we outline the appropriate ...
Implementation of wall functions into a hybrid fictitious domain-immersed boundary method
Kubíčková, Lucie; Isoz, Martin
2023 - anglický
Hybrid fictitious domain-immersed boundary method (HFDIB) is a simulation approach used in computational fluid dynamics. The approach avoids usage of complex geometry-conforming computational domains. Instead, a simple domain is used and the geometry is projected onto it by a scalar field and adjustment of governing equations. Hence, the time spent on mesh generation is substantially reduced. It is advantageous to use the HFDIB in geometry optimizations where it allows for a massive optimization speed-up. Nevertheless, there is a problem with simulation of the fluid behavior in the boundary layer in the vicinity of the immersed walls. Especially, in simulation of highly turbulent flows, where the boundary layer is very thin and the usage of finer mesh is unaffordable. In this work, we aim to solve this problem by implementation of Reynolds averaged turbulence models in our custom HFDIB variant. In particular, we implemented the k-ω turbulence model and blended wall functions for closure variables and velocity.
Klíčová slova:
wall functions; immersed boundary method; CFD; RAS
Dokument je dostupný na externích webových stránkách.
Implementation of wall functions into a hybrid fictitious domain-immersed boundary method
Hybrid fictitious domain-immersed boundary method (HFDIB) is a simulation approach used in computational fluid dynamics. The approach avoids usage of complex geometry-conforming computational domains. ...
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