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ON OUR RECENT WORK IN STUDYING NEW PARTICLE FORMATION (NPF)
Kovářík, Jiří; Špalová, Anna; Roztočil, Petr; Zíková, Naděžda; Schwarz, Jaroslav; Ždímal, Vladimír
2023 - anglický
New particle formation (NPF) is increasingly gaining attention since it emerged roughly twenty years ago as a field of interest within the aerosol science. It studies the transition process between gas phase molecules, forming clusters and eventually becoming aerosol particles. Thus, this field is a multidisciplinary one, ranging from meteorology, atmospheric chemistry and physics, all the way through physical chemistry towards chemistry and physics of aerosols. \nRecent development of instrumentation techniques allows measuring of sub-5 nm particles and molecule clusters, neutral and also charged ones. Therefore, modern analytical methods based on these measurements are often used for NPF studies.
Klíčová slova:
atmospheric aerosols; new particle formation; NAIS
Plné texty jsou dostupné v digitálním repozitáři NUŠL
ON OUR RECENT WORK IN STUDYING NEW PARTICLE FORMATION (NPF)
New particle formation (NPF) is increasingly gaining attention since it emerged roughly twenty years ago as a field of interest within the aerosol science. It studies the transition process between ...
GA 19-07635S: Outputs and Results
Rehák, Branislav
2023 - anglický
This manuscript aims to deliver a survey of results obtained during the solution of the project No. GA19-07635S of the Czech Science Foundation. The timespan dedicated to the work on this project was 1.3.2019 - 30.6.2022. The main area dealt with were\nnonlinear multi-agent systems and their synchronization, further, attention was paid to some auxiliary results in the area of nonlinear observers. This Report briefly introduces the Project, provides a summary of the results obtained and also sketches an outline how these results will be applied and extended in future.
Klíčová slova:
multi-agent systems; nonlinear multi-agent systems; synchronization
Dokument je dostupný na externích webových stránkách.
GA 19-07635S: Outputs and Results
This manuscript aims to deliver a survey of results obtained during the solution of the project No. GA19-07635S of the Czech Science Foundation. The timespan dedicated to the work on this project was ...
On the structure and values of betweenness centrality in dense betweenness-uniform graphs
Ghanbari, B.; Hartman, David; Jelínek, V.; Pokorná, Aneta; Šámal, R.; Valtr, P.
2023 - anglický
Betweenness centrality is a network centrality measure based on the amount of shortest paths passing through a given vertex. A graph is betweenness-uniform (BUG)if all vertices have an equal value of betweenness centrality. In this contribution, we focus on betweenness-uniform graphs with betweenness centrality below one. We disprove a conjecture about the existence of a BUG with betweenness value α for any rational numberαfrom the interval (3/4,∞) by showing that only very few betweenness centrality values below 6/7 are attained for at least one BUG. Furthermore, among graphs with diameter at least three, there are no betweenness-uniform graphs with a betweenness centrality smaller than one. In graphs of smaller diameter, the same can be shown under a uniformity condition on the components of the complement.
Klíčová slova:
betweenness; graphs
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
On the structure and values of betweenness centrality in dense betweenness-uniform graphs
Betweenness centrality is a network centrality measure based on the amount of shortest paths passing through a given vertex. A graph is betweenness-uniform (BUG)if all vertices have an equal value of ...
Professional survey forecasts and expectations in DSGE models
Rychalovska, Y.; Slobodyan, Sergey; Wouters, R.
2023 - anglický
In this paper, we demonstrate the usefulness of survey data for macroeconomic analysis and propose a strategy to integrate and efficiently utilize information from surveys in the DSGE setup. We extend the set of observable variables to include the data on consumption, investment, output, and inflation expectations, as measured by the Survey of Professional Forecasters (SPF). By doing so, we aim to discipline the dynamics of model-based expectations and evaluate alternative belief models. Our approach to exploit the timely information from surveys is based on re-specification of structural shocks into persistent and transitory components. Due to the SPF, we are able to improve identification of fundamental shocks and predictive power of the model by separating the sources of low and high frequency volatility. Furthermore, we show that models with an imperfectly-rational expectation formation mechanism based on Adaptive Learning (AL) can reduce important limitations implied by the Rational Expectation (RE) hypothesis. More specifically, our models based on belief updating can better capture macroeconomic trend shifts and, as a result, achieve superior long-term predictions. In addition, the AL mechanism can produce realistic time variation in the transmission of shocks and perceived macro-economic volatility, which allows the model to better explain the investment dynamics. Finally, AL models, which relax the RE constraint of internal consistency between the agents’ and model forecasts, can reproduce the main features of agents’ predictions in line with SPF evidence and, at the same time, can generate improved model forecasts, thus diminishing possible inefficiencies present in surveys.
Klíčová slova:
expectations; survey data; adaptive learning
Dokument je dostupný na externích webových stránkách.
Professional survey forecasts and expectations in DSGE models
In this paper, we demonstrate the usefulness of survey data for macroeconomic analysis and propose a strategy to integrate and efficiently utilize information from surveys in the DSGE setup. We extend ...
Gender gap in reported childcare preferences among parents
Pertold, Filip; Sinani, S.; Šoltés, M.
2023 - anglický
The child penalty explains the majority of gender employment and wage gaps, however, less is known about the factors driving the child penalty itself. In this paper, we study the gender gap in childcare preferences as a potential factor that contributes to the child penalty. We surveyed Czech parents and elicited the minimal compensation they would require to stay home to care for a child. Mothers require less compensation for childcare than fathers. The estimated gender gap in childcare preferences is CZK 2,500 monthly, 7.6% of the median female wage, and cannot be explained by differences in labor market opportunities or prosocial motives to care for a family member. We further document widespread misperception of fathers’ preferences, as respondents incorrectly expect fathers to require less to care for a child than to care for an elderly parent.\n
Klíčová slova:
childcare; gender wage gap; gender employment gap
Dokument je dostupný na externích webových stránkách.
Gender gap in reported childcare preferences among parents
The child penalty explains the majority of gender employment and wage gaps, however, less is known about the factors driving the child penalty itself. In this paper, we study the gender gap in ...
On the development of a numerical model for the simulation of air flow in the human airways
Lancmanová, Anna; Bodnár, Tomáš; Sequeira, A.
2023 - anglický
This contribution reports on an ongoing study focusing on reduced order models for incompressible viscous fluid flow in two dimensional channels. A finite difference solver was developed using a simple implementation of the immersed boundary method to represent the channel geometry. The solver was validated for unsteady flow by comparing the obtained two-dimensional numerical solutions with analytical profiles computed from the Womersley solution. Finally the 2D model was coupled to a simple 1D extension simulating the flow in axisymmetric elastic vessel (tube). Some of the coupling principles and implementation issues are discussed in detail.
Klíčová slova:
reduced order model; incompressible Navier-Stokes equations; finite difference approximation; coupling method
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
On the development of a numerical model for the simulation of air flow in the human airways
This contribution reports on an ongoing study focusing on reduced order models for incompressible viscous fluid flow in two dimensional channels. A finite difference solver was developed using a ...
Simulating particle-laden flows: from immersed boundaries towards model order reduction
Isoz, Martin; Kubíčková, Lucie; Kotouč Šourek, M.; Studeník, Ondřej; Kovárnová, A.
2023 - anglický
Particle-laden flow is prevalent both in nature and in industry. Its appearance ranges from the trans-port of riverbed sediments towards the magma flow, from the deposition of catalytic material inside particulate matter filters in automotive exhaust gas aftertreatment towards the slurry transport in dredging operations. In this contribution, we focus on the particle-resolved direct numerical simulation (PR-DNS) of the particle-laden flow. Such a simulation combines the standard Eulerian approach to computational fluid dynamics (CFD) with inclusion of particles via a variant of the immersed boundary method (IBM) and tracking of the particles movement using a discrete element method (DEM). Provided the used DEM allows for collisions of arbitrarily shaped particles, PR-DNS is based (almost) entirely on first principles, and as such it is a truly high-fidelity model. The downside of PR-DNS is its immense computational cost. In this work, we focus on three possibilities of alleviating the computational cost of PR-DNS: (i) replacing PR-DNS by PR-LES or PR-RANS, while the latter requires combining IBM with wall functions, (ii) improving efficiency of DEM contact solution via adaptively refined virtual mesh, and (iii) developing a method of model order reduction specifically tailored to PR-DNS of particle-laden flows.
Klíčová slova:
particle-laden flow; CFD-DEM; arbitrarily-shaped particles; finite volume method
Dokument je dostupný na externích webových stránkách.
Simulating particle-laden flows: from immersed boundaries towards model order reduction
Particle-laden flow is prevalent both in nature and in industry. Its appearance ranges from the trans-port of riverbed sediments towards the magma flow, from the deposition of catalytic material ...
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, ...
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