Numerical evaluation of mass-diffusive compressible fluids flows models
Bodnár, Tomáš; Fraunié, P.
2024 - English This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high resolution compact finite difference scheme with strong stability preserving RungeKutta time stepping. The two simple but challenging computational test cases are presented, based on the double-periodic shear layer and the Kelvin-Helmholtz instability. The obtained time-dependent flow fields are showing pronounced shear and vorticity layers being resolved by the standard as well as by the new mass-diffusive modified models. The preliminary results show that the new models are viable alternative to the well established classical models. Keywords: compressible Navier-Stokes; nearly incompressible flow; mass diffusion; compact finite-difference Available in digital repository of the ASCR Numerical evaluation of mass-diffusive compressible fluids flows models

This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high ...

Bodnár, Tomáš; Fraunié, P.
Matematický ústav, 2024

Motion of fluids in the moving domain
Nečasová, Šárka
2024 - English It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied. Keywords: compressible fluid; moving domain; weak solutions Available in digital repository of the ASCR Motion of fluids in the moving domain

It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied.

Nečasová, Šárka
Matematický ústav, 2024

Práce mimo pracoviště a hybridní práce
VÚBP
2024 - Czech Zvýšená prevalence práce na dálku v důsledku pandemie covid-19 vedla ke zvýšenému zájmu o tuto formu organizace práce a její dopad na pohodu a zdraví zaměstnanců. Práci na dálku lze definovat jako jakýkoli typ uspořádání práce zahrnující používání osobních počítačů, chytrých telefonů, notebooků, softwarových balíčků a internetu k práci z domova nebo obecněji mimo pracoviště zaměstnavatele po většinu pracovní doby nebo její část. Keywords: hybridní práce; práce na dálku; home office; remote work; hybrid work; home office Available in a digital repository NRGL Práce mimo pracoviště a hybridní práce

Zvýšená prevalence práce na dálku v důsledku pandemie covid-19 vedla ke zvýšenému zájmu o tuto formu organizace práce a její dopad na pohodu a zdraví zaměstnanců. Práci na dálku lze definovat jako ...

VÚBP
Výzkumný ústav bezpečnosti práce, v.v.i., 2024

Rizika reformy doktorského studia
Grosman, Jiří; Jurajda, Štěpán; Münich, Daniel
2024 - Czech Systém financování doktorského studia v České republice je dlouhodobě neefektivní. Dokončovaná reforma má za cíl efektivitu systému výrazně zvýšit. V tomto krátkém textu upozorňujeme na potenciální problémy spojené s rozdělováním veřejné finanční podpory doktorského studia mezi vysoké školy. Problematické by bylo rozdělování podpory založené dominantně na míře úspěšného dokončování studií. Alokace veřejné podpory doktorského studia by vedle opodstatněných národních oborových priorit měla zohledňovat výsledky hodnocení kvality vědy na vysokých školách a úspěšnost v kariérním umisťování absolventů. The system of financing doctoral studies in the Czech Republic has long been inefficient. A reform currently underway aims to significantly increase the efficiency of the system. In this short text, we draw attention to potential problems associated with the distribution of public financial support for doctoral studies among universities. It would be problematic to distribute support based predominantly on degree completion rates. Allocation of public support for doctoral studies should take into account the results of evaluations of the quality of science produced by universities and their success in career placement of graduates, in addition to justifiable national disciplinary priorities. Keywords: doctoral studies; public financial support; Czech Republic Fulltext is available at external website. Rizika reformy doktorského studia

Systém financování doktorského studia v České republice je dlouhodobě neefektivní. Dokončovaná reforma má za cíl efektivitu systému výrazně zvýšit. V tomto krátkém textu upozorňujeme na potenciální ...

Grosman, Jiří; Jurajda, Štěpán; Münich, Daniel
Národohospodářský ústav, 2024

Financial skills and search in the mortgage market
Cota, Marta; Šterc, Ante
2024 - English Are households with low financial skills disadvantaged in the mortgage market? Using stochastic record linking, we construct a unique U.S. dataset encompassing a rich set of mortgage details and borrowers’ characteristics, including their objective financial literacy measure. We find that households with low financial literacy are up to 4% more likely to search less and lock in at 15-20 b.p. higher rates. Upon origination, unskilled borrowers face a 35-45% higher mortgage delinquency and end up with a 30% lower likelihood of refinancing. Overall, for a $100,000 loan, the potential losses from low financial literacy are more than $9,329 over the mortgage duration. To understand how financial education, more accessible mortgages, or mortgage rate changes affect households with low financial literacy, we formulate and calibrate a mortgage search model with heterogeneous search frictions and endogenous financial skills. Our model estimates show that search intensity and financial skill variations contribute to 55% and 10% of mortgage rate variations, respectively. We find that i) more accessible mortgages lead to a higher delinquency risk among low-skilled households, ii) financial education mitigates the adverse effects of increased accessibility, and iii) low mortgage rates favor high-skilled homeowners and, by reinforcing refinancing activity, deepen consumption differences across different financial skill levels. Keywords: mortgage refinancing; mortgage search; financial skills Fulltext is available at external website. Financial skills and search in the mortgage market

Are households with low financial skills disadvantaged in the mortgage market? Using stochastic record linking, we construct a unique U.S. dataset encompassing a rich set of mortgage details and ...

Cota, Marta; Šterc, Ante
Národohospodářský ústav, 2024

Zoologické dny Brno 2023: sborník abstraktů z konference 9.-10. února 2023
Bryja, Josef; Horsák, M.; Horsáková, V.
2023 - Czech Keywords: zoology; conference Fulltext is available at external website. Zoologické dny Brno 2023: sborník abstraktů z konference 9.-10. února 2023

Bryja, Josef; Horsák, M.; Horsáková, V.
Ústav biologie obratlovců, 2023

Some modifications of the limited-memory variable metric optimization methods
Vlček, Jan; Lukšan, Ladislav
2023 - English Several modifications of the limited-memory variable metric (or quasi-Newton) line search methods for large scale unconstrained optimization are investigated. First the block version of the symmetric rank-one (SR1) update formula is derived in a similar way as for the block BFGS update in Vlˇcek and Lukˇsan (Numerical Algorithms 2019). The block SR1 formula is then modified to obtain an update which can reduce the required number of arithmetic operations per iteration. Since it usually violates the corresponding secant conditions, this update is combined with the shifting investigated in Vlˇcek and Lukˇsan (J. Comput. Appl. Math. 2006). Moreover, a new efficient way how to realize the limited-memory shifted BFGS method is proposed. For a class of methods based on the generalized shifted economy BFGS update, global convergence is established. A numerical comparison with the standard L-BFGS and BNS methods is given. Keywords: unconstrained minimization; variable metric methods; limited-memory methods; variationally derived methods; arithmetic operations reduction; global convergence Available in a digital repository NRGL Some modifications of the limited-memory variable metric optimization methods

Several modifications of the limited-memory variable metric (or quasi-Newton) line search methods for large scale unconstrained optimization are investigated. First the block version of the symmetric ...

Vlček, Jan; Lukšan, Ladislav
Ústav informatiky, 2023

Utilization of electrochemically induced cleavage of various sulfonimides
Salvadori, Karolína
2023 - English In this work, we describe the unexpected electrochemical cleavage of sulfonimides, providing a direct pathway to corresponding sulfonamides. For this purpose, 16 substances were synthesized and tested, reflecting the influence of different electron effects of -SO2Ph-R substituents, and the impact of the number of nosyl units present in molecules. In the case of octakis-nosylated calixarenes, the electrochemical cleavage via direct potential-controlled electrolysis was compared with conventional organic synthetic procedures. After electrolysis, all prepared sulfonamides were isolated in excellent yields. Keywords: sulfonimides; green chemistry procedures; electrochemisty Available in a digital repository NRGL Utilization of electrochemically induced cleavage of various sulfonimides

In this work, we describe the unexpected electrochemical cleavage of sulfonimides, providing a direct pathway to corresponding sulfonamides. For this purpose, 16 substances were synthesized and ...

Salvadori, Karolína
Ústav chemických procesů, 2023

Green approach for the preparation of biosourced ionic liquids and the study of their thermodynamic properties\n
Souvenir Zafindrajaona, Mahasoa-Salina
2023 - English This presentation will address a green approach to the synthesis of ionic liquids qualified as biosourced (monocatenar or bolaform systems) from specific agro-resources, according to several principles of green chemistry. As these solvents could be used to solubilize lignocellulosic biomass and/or extract bioactive compounds (from plant sourcing), the physicochemical characteristics (density, viscosity and heat capacity) of pure ILs or mixtures of IL/water must be determined. Preliminary results concerning this last point will be presented. Keywords: biosourced ionic liquids; lignocellulosic biomass; thermodynamic properties Available in a digital repository NRGL Green approach for the preparation of biosourced ionic liquids and the study of their thermodynamic properties\n

This presentation will address a green approach to the synthesis of ionic liquids qualified as biosourced (monocatenar or bolaform systems) from specific agro-resources, according to several ...

Souvenir Zafindrajaona, Mahasoa-Salina
Ústav chemických procesů, 2023

Cultivation of Limnospira maxima and utilization of its fresh biomass in human nutrition
Vásquez, Claudia
2023 - English This work aims to enhance productivity, efficiency and sustainability of L. maxima cultivation as well as to determine the safe microbiological conditions for the nutritional use of fresh spirulina biomass. Various parameters such as light intensity, light spectral composition, temperature, pH, CO2, and culture media composition can be optimized. A series of experiments were performed to find the most suitable configuration to cultivate L. maxima, defined by cyanobacterium productivity and yield as well as other metabolites production such as phycocyanin (C-PC) and carotenoids. Keywords: Limnospira maxima; fresh biomass; human nutrition Available in a digital repository NRGL Cultivation of Limnospira maxima and utilization of its fresh biomass in human nutrition

This work aims to enhance productivity, efficiency and sustainability of L. maxima cultivation as well as to determine the safe microbiological conditions for the nutritional use of fresh spirulina ...

Vásquez, Claudia
Ústav chemických procesů, 2023