Ano (5803)
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On Reynolds-averaged turbulence modeling with immersed boundary method
Kubíčková, Lucie; Isoz, Martin
2023 - anglický
The immersed boundary (IB) method is an approach in the computational fluid dynamics in which complex geometry conforming meshes are replaced by simple ones and the true simulated geometry is projected onto the simple mesh by a scalar field and adjustment of governing equations. Such an approach is particularly advantageous in topology optimizations (TO) where it allows for substantial speed-up since a single mesh can be used for all the tested topologies. In our previous work, we linked our custom IB variant, the hybrid fictitious domain-immersed boundary method (HFDIB), with a TO framework and successfully carried out an optimization under laminar flow conditions. However, to allow for optimizations of reallife components, the IB approach needs to be coupled with an affordable turbulence modeling. In this contribution, we focus on extending the HFDIB approach by the possibility to perform Reynolds-averaged simulations (RAS). In particular, we implemented the k − ω turbulence model and wall functions for closure variables and velocity.
Klíčová slova:
immersed boundary; RAS; wall functions; CFD; OpenFOAM
Dokument je dostupný na externích webových stránkách.
On Reynolds-averaged turbulence modeling with immersed boundary method
The immersed boundary (IB) method is an approach in the computational fluid dynamics in which complex geometry conforming meshes are replaced by simple ones and the true simulated geometry is ...
Finite element modal analysis of a silicone vocal fold filled with fluid
Hájek, P.; Radolf, Vojtěch; Horáček, Jaromír; Švec, J. G.
2023 - anglický
A three dimensional (3D) finite element (FE) model of a silicone vocal fold (VF) filled with fluid is presented here. The silicone part of the model is based on partial differential equations of the continuum mechanics and consider large deformations. The fluid domain encapsulated in the silicone VF is defined semianalytically as a lumped-element model describing the fluid in hydrostatic conditions. The elongated and pressurized silicone VF was subjected to perturbed modal analysis. Results showed that the choice of the fluid inside the VF substantially influences the natural frequencies. Namely, the water-filling lowers the natural frequencies approximately by half over the air-filling. Besides, the procedure of reverse engineering for obtaining the geometry of the VF from already 3D-printed mold is introduced.
Klíčová slova:
perturbed modal analysis; finite element method; vocal folds; reverse engineering; biomechanics of voice
Dokument je dostupný na externích webových stránkách.
Finite element modal analysis of a silicone vocal fold filled with fluid
A three dimensional (3D) finite element (FE) model of a silicone vocal fold (VF) filled with fluid is presented here. The silicone part of the model is based on partial differential equations of the ...
Key barriers, opportunities and good practices for entrepreneurship and innovation
Křížková, Alena; Marková Volejníčková, Romana; Pospíšilová, Marie; Vohlídalová, Marta
2023 - anglický
The report is focused on barriers, opportunities and good practices for gender-sensitive innovations and entrepreneurship. It is based on the analysis of 36 interviews with experts from the health, green and digital fields and the target groups defined in the quadruple helix of academia, citizens, industry, and government. The interviews were collected by 12 GILL partners in the 10 consortium countries in 2023. Gender stereotypical cultural beliefs and norms, masculine bias, gender segregation, lack of funding, lack of policies to support work-life balance and lack of political will and empirical evidence to remove these barriers are the main problems identified. The opportunities reflected largely correspond to these barriers and highlight the role of key actors, such as the EU, in setting standards. Projects focusing on fixing the number of women under-represented in certain fields and occupations and management positions predominate among good practices.
Klíčová slova:
.gender equality; gender in entrepreneurship; gender in science; gender in innovation; gender stereotypes; good practices
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Key barriers, opportunities and good practices for entrepreneurship and innovation
The report is focused on barriers, opportunities and good practices for gender-sensitive innovations and entrepreneurship. It is based on the analysis of 36 interviews with experts from the health, ...
Proměny interpretace hudebního folkloru: od ochrany každodenní kultury po vznik hudebního žánru (na příkladu České republiky)
Uhlíková, Lucie; Pavlicová, M.
2023 - český
Od 60. let 20. století se v české etnologii začaly rozvíjet snahy, které postupně začaly zařazovat projevy folkloru v jejich druhé existenci do odborného výzkumu. Oblast folklorismu se někdy překrývala s existujícími lidovými tradicemi, někdy na ně navazovala a někdy se jimi pouze v různé míře inspirovala. Rozlišení v takto vymezených kategoriích nebylo snadné ani v minulosti a s příchodem stále rychlejším vývojem společnosti se v obecném povědomí rozostřilo. V tomto rámci vznikl současný široký hudební žánr zakořeněný v hudebním folkloru, který není snadné obsahově vymezit. Příspěvek nastiňuje průběh jeho historického formování, ukazuje modelové momenty jeho vývoje a zabývá se jeho polyfunkčností: mnoho kolektivů se prezentuje nejen na jevišti (spolu s tanečníky) a v hudebních pořadech. koncertním prostředí (samostatně), podílí se ale také na místních etnokulturních tradicích, tanečních zábavách, rodinných oslavách (svatby, narozeniny) a komerčně zaměřených akcích. akce. K ilustraci popsaných faktů článek využívá archivní pramenný materiál a terénní výzkum založený na základě rozhovorů s vybranými hudebníky From the 1960s onwards, efforts began to develop in Czech ethnology, which gradually began to include folklore manifestations in their second existence in professional research. The field of folklorism sometimes overlapped with the existence of folk traditions, sometimes built on them, and sometimes was only inspired by them to varying degrees. The distinction in such defined categories was not easy even in the past, and with the increasingly rapid development of society, it became blurred in the general consciousness. Within this scope, a contemporary broad music genre, music folklore, has emerged that is not easy to define in terms of content. In this paper, the authors outline its historical formation, show model moments of its development, and deal with its polyfunctionality: many collectives present themselves not only on stage (together with dancers) and in concert settings (independently), but also participate in local ethno-cultural traditions, dance parties, family celebrations (weddings, birthdays), and commercially focused events. To illustrate this, the paper uses archival source material, and field research based on interviews with selected musicians.
Klíčová slova:
Music folklore; transformations of folk tradition; music genre; folk revivalism in the Czech Republic
Dokument je dostupný na externích webových stránkách.
Proměny interpretace hudebního folkloru: od ochrany každodenní kultury po vznik hudebního žánru (na příkladu České republiky)
Od 60. let 20. století se v české etnologii začaly rozvíjet snahy, které postupně začaly zařazovat projevy folkloru v jejich druhé existenci do odborného výzkumu. Oblast folklorismu se někdy ...
From John Graunt to Adolphe Quetelet: on the Origins Of Demography
Kalina, Jan
2023 - anglický
John Graunt (1620-1674) and Adolphe Quetelet (1796-1874) were two important personalities, who contributed to the origins of demography. As they both developed statistical techniques for the analysis of demographic data, they are important also from the point of view of history of statistics. The contributions of both Graunt and Quetelet especially to the development of mortality tables and models are recalled in this paper. Already from the 17th century, the available mortality tables were exploited for computing life annuities. Also the contribution of selected personalities inspired by Graunt are recalled here, the work of Christian Huygens, Jacob Bernoulli, or Abraham de Moivre is discussed to document that the historical development of statistics and probability theory was connected with the development of demography.
Klíčová slova:
history of demography; history of statistics; probability theory; moral statistics; mortality tables
Dokument je dostupný na externích webových stránkách.
From John Graunt to Adolphe Quetelet: on the Origins Of Demography
John Graunt (1620-1674) and Adolphe Quetelet (1796-1874) were two important personalities, who contributed to the origins of demography. As they both developed statistical techniques for the analysis ...
MAD UFOs: Magnetically Arrested Discs with persistent Ultra-Fast Outflows
Suková, Petra; Zajaček, M.; Karas, Vladimír
2023 - anglický
We study an outflow that develops in the MAD state in 3D GRMHD simulations. We show that the outflow can be accelerated to\nrelativistic velocities and persist over the course of our simulation. We compare the properties of the outflow from MAD discs with those launched by orbiting secondary at close orbit. The main difference is that the orbiting body launches a more coherent, quasiperiodic ultrafast outflow at lower velocities (v < 0.5c) while the outflow launched in the MAD state (without the body) has a stochastic behaviour and has anapproximately flat velocity distribution between lower anf higher outflow velocities, 0.2c < v < 0.3c and v > 0.5c.
Klíčová slova:
accretion discs; black holes; active galactic nuclei
Dokument je dostupný na externích webových stránkách.
MAD UFOs: Magnetically Arrested Discs with persistent Ultra-Fast Outflows
We study an outflow that develops in the MAD state in 3D GRMHD simulations. We show that the outflow can be accelerated to\nrelativistic velocities and persist over the course of our simulation. We ...
TESTING THE METHOD OF MULTIPLE SCALES AND THE AVERAGING PRINCIPLE FOR MODEL PARAMETER ESTIMATION OF QUASIPERIODIC TWO TIME-SCALE MODELS
Papáček, Štěpán; Matonoha, Ctirad
2023 - anglický
Some dynamical systems are characterized by more than one timescale, e.g. two well separated time-scales are typical for quasiperiodic systems. The aim of this paper is to show how singular perturbation methods based on the slow-fast decomposition can serve for an enhanced parameter estimation when the slowly changing features are rigorously treated. Although the ultimate goal is to reduce the standard error for the estimated parameters, here we test two methods for numerical approximations of the solution of associated forward problem: (i) the multiple time-scales method, and (ii) the method of averaging. On a case study, being an under-damped harmonic oscillator containing two state variables and two parameters, the method of averaging gives well (theoretically predicted) results, while the use of multiple time-scales method is not suitable for our purposes.
Klíčová slova:
Dynamical system; Singular perturbation; Averaging; Parameter estimation; Slow-fast decomposition; Damped oscillations
Dokument je dostupný na externích webových stránkách.
TESTING THE METHOD OF MULTIPLE SCALES AND THE AVERAGING PRINCIPLE FOR MODEL PARAMETER ESTIMATION OF QUASIPERIODIC TWO TIME-SCALE MODELS
Some dynamical systems are characterized by more than one timescale, e.g. two well separated time-scales are typical for quasiperiodic systems. The aim of this paper is to show how singular ...
Inflation expectations in the wake of the war in Ukraine
Afunts, Geghetsik; Cato, M.; Schmidt, T.
2023 - anglický
Russia's invasion of Ukraine is posing a range of new challenges to the global economy, including affecting the inflation expectations of individuals. In this paper, we aim to quantify the effect of the invasion on short- and long-term inflation expectations of individuals in Germany. We use microdata from the Bundesbank Online Panel - Households (BOP-HH), for the period from February 15th to March 29th, 2022. Treating the unanticipated start of the war in Ukraine on the 24th of February 2022 as a natural experiment, we find that both short- and long-term inflation expectations increased as an immediate result of the invasion. Long-term inflation expectations increased by around 0.4 percentage points, while the impact on short-term inflation expectations was more than twice as large - around one percentage point. Looking into the possible mechanisms of this increase, we suggest that it can be partially attributed to individuals’ fears of soaring energy prices and increasing pessimism about economic trends in general. Our results indicate that large economic shocks can have a substantial impact on both short and long-term inflation expectations.
Klíčová slova:
inflation expectations; Russian invasion of Ukraine; survey
Dokument je dostupný na externích webových stránkách.
Inflation expectations in the wake of the war in Ukraine
Russia's invasion of Ukraine is posing a range of new challenges to the global economy, including affecting the inflation expectations of individuals. In this paper, we aim to quantify the effect of ...
Ruce a mozky českých žen stále nevyužity
Grossmann, Jakub; Münich, Daniel
2023 - český
Tato analýza mapuje celoživotní profily míry zaměstnanosti a odpracované doby Češek a změny za posledních dvacet let. Klíčová zjištění jsou popsána formou komentovaných grafů. Ekonomické a statistické detaily jsou popsány v doprovodných textech. This analysis maps life-long profiles in the unemployment rate and hours worked by Czech women and changes in these over the past twenty years. Its key findings are presented in the form of graphs with commentary. The economic and statistic details are provided in the accompanying texts.
Klíčová slova:
labour market; women; Czech Republic
Dokument je dostupný na externích webových stránkách.
Ruce a mozky českých žen stále nevyužity
Tato analýza mapuje celoživotní profily míry zaměstnanosti a odpracované doby Češek a změny za posledních dvacet let. Klíčová zjištění jsou popsána formou komentovaných grafů. Ekonomické a statistické ...
Vývoj postojů české veřejnosti k válečným uprchlíkům z Ukrajiny
Münich, Daniel; Protivínský, Tomáš
2023 - český
Po vojenském útoku Ruska na Ukrajinu koncem února 2022 v Česku převládla atmosféra solidarity a většina Čechů přijímání válečných uprchlíků podporovala. Tato podpora do konce listopadu klesla zhruba o čtvrtinu. Podobně se zhoršovala vnímaná míra integrace Ukrajinců do české společnosti. Změna postojů české společnosti v čase však nevycházela primárně z osobní zkušenosti a z prožitého příchodu uprchlíků, ale souvisela spíše s postupně opadávajícím zájmem po vypuknutí konfliktu a prvotním šoku. Ačkoli se integrace Ukrajinců v některých dimenzích ve druhé polovině roku 2022 reálně zlepšila, například ve školách nebo na trhu práce, do vnímání české společnosti se tyto dílčí pokroky nepromítly. In the wake of Russia’s military assault on Ukraine at the end of February 2022, an atmosphere of solidarity prevailed in the Czech Republic and most of the Czech population supported the country’s intake of war refugees. By the end of November 2022, that support had fallen by approximately one quarter. Czechs’ perceptions of how well integrated Ukrainians were into Czech society worsened similarly. This change in Czech public attitudes over time did not, however, stem primarily from personal or first hand experience of welcoming refugees, rather, it was related to a gradual decrease in public interest in the conflict after the initial shock of it first beginning. Although several aspects of Ukrainian refugees’ integration improved in real terms in the second half of 2022, for example in relation to schools and to the labour market, this progress was not reflected in Czech public opinion.
Klíčová slova:
Ukrainian refugees; views and attitudes; Czech Republic
Dokument je dostupný na externích webových stránkách.
Vývoj postojů české veřejnosti k válečným uprchlíkům z Ukrajiny
Po vojenském útoku Ruska na Ukrajinu koncem února 2022 v Česku převládla atmosféra solidarity a většina Čechů přijímání válečných uprchlíků podporovala. Tato podpora do konce listopadu klesla zhruba o ...
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