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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 ...
Different Boundary Conditions For LES Solver PALM 6.0 Used for ABL in Tunnel Experiment
Řezníček, Hynek; Geletič, Jan; Bureš, Martin; Krč, Pavel; Resler, Jaroslav; Vrbová, Kateřina; Trush, Arsenii; Michálek, Petr; Beneš, L.; Sühring, M.
2023 - anglický
We tried to reproduce results measured in the wind tunnel experiment with a CFD simulation provided by numerical model PALM. A realistic buildings layout from the Prague-Dejvice quarter has been chosen as a testing domain because solid validation campaign for PALM simulation of Atmospheric Boundary Layer (ABL) over this quarter was documented in the past. The question of input data needed for such simulation and capability of the model to capture correctly the inlet profile and its turbulence structure provided by the wind-tunnel is discussed in the study The PALM dynamical core contains a solver for the Navier-Stokes equations. By default, the model uses the Large Eddy Simulation (LES) approach in which the bulk of the turbulent motions is explicitly resolved. It is well validated tool for simulations of the complex air-flow within the real urban canopy and also within its reduced scale provided by wind tunnel experiments. However the computed flow field between the testing buildings did not correspond well to the measured wind velocity in some points. Different setting of the inlet boundary condition was tested but none of them gave completely developed turbulent flow generated by vortex generators and castellated barrier wall place at the entrance of the aerodynamic section of the wind tunnel.
Klíčová slova:
large eddy simulation; wind tunnel; atmospheric boundary layer; PALM model; turbulence
Dokument je dostupný na externích webových stránkách.
Different Boundary Conditions For LES Solver PALM 6.0 Used for ABL in Tunnel Experiment
We tried to reproduce results measured in the wind tunnel experiment with a CFD simulation provided by numerical model PALM. A realistic buildings layout from the Prague-Dejvice quarter has been ...
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 ...
Ambiguity in Stochastic Optimization Problems with Nonlinear Dependence on a Probability Measure via Wasserstein Metric
Kaňková, Vlasta
2023 - anglický
Many economic and financial applications lead to deterministic optimization problems depending on a probability measure. It happens very often (in applications) that these problems have to be solved on the data base. Point estimates of an optimal value and estimates of an optimal solutionset can be obtained by this approach. A consistency, a rate of convergence and normal properties, of these estimates, have been discussed (many times) not only under assumptions of independent data corresponding to the distributions with light tails, but also for weak dependent data and the distributions with heavy tails. However, it is also possible to estimate (on the data base) a confidence intervals and bounds for the optimal value and the optimal solutions. To analyze this approach we focus on a special case of static problems depending nonlineary on the probability measure. Stability results based on the Wasserstein metric and the Valander approach will be employed for the above mentioned analysis.
Klíčová slova:
Stochastic optimization problems; static problems; empirical measure; point estimates; interval estimates; nonlinear dependence
Dokument je dostupný na externích webových stránkách.
Ambiguity in Stochastic Optimization Problems with Nonlinear Dependence on a Probability Measure via Wasserstein Metric
Many economic and financial applications lead to deterministic optimization problems depending on a probability measure. It happens very often (in applications) that these problems have to be solved ...
Dissolved and gaseous nitrogen losses in forests controlled by soil nutrient stoichiometry
Oulehle, Filip; Chuman, T.; Hruška, Jakub; Krám, Pavel; Navrátil, Tomáš; Tesař, Miroslav; Ač, Alexander; Urban, Otmar
2023 - anglický
This study investigates the consequences of chronic nitrogen deposition in forests, including its effects on soil and surface water quality, and greenhouse gas emissions. To predict these effects, the authors explore the controls over dissolved and gaseous nitrogen fluxes in temperate forests. Their findings indicate that stream leaching losses of dissolved nitrogen correspond with the nutrient stoichiometry\nof the forest floor, with stream N losses increasing as ecosystems progress towards phosphorus limitation. Soil nitrogen storage increases with oxalate extractable iron and aluminium content. The authors estimate soil gaseous losses based on 15 N stocks, which averaged 2.5±2.2 kg N ha-1 year-1 , comprising 20±14% of total nitrogen deposition. They also extrapolate the current gaseous nitrogen loss flux from forests globally to be 8.9 Tg N year-1 , which represents 39% of current nitrogen deposition to forests worldwide.
Klíčová slova:
nitrogen; catchment; isotope; mass balance; denitrification; carbon; sequestration
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Dissolved and gaseous nitrogen losses in forests controlled by soil nutrient stoichiometry
This study investigates the consequences of chronic nitrogen deposition in forests, including its effects on soil and surface water quality, and greenhouse gas emissions. To predict these effects, the ...
Hazardous components: A case study in textile waste management
Shtukaturova, Anastasia
2023 - anglický
Textile waste, a problem that has been somewhat overlooked for many years, is now coming to the fore.1 The textile value chain is long\nand complex, with over 8000 chemicals used in different manufacturing processes.2 A wide variety of chemicals are used in the manufacture of textile products for the improvement of essential properties and performance of textiles. Chemicals used in textiles significantly improve their quality and appearance. However, the harmful effects of these chemicals can occur at various stages of textile production and processing, such as dyeing, printing and finishing, as well as during use by consumers and at the end-of-life stage.3 There is a lack of safety information on the presence and use of all of these chemicals in consumer products.
Klíčová slova:
textile waste; waste management; chemicals
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Hazardous components: A case study in textile waste management
Textile waste, a problem that has been somewhat overlooked for many years, is now coming to the fore.1 The textile value chain is long\nand complex, with over 8000 chemicals used in different ...
Properties and use of high-temperature biochar
Sedmihradská, Anežka
2023 - anglický
Despite being a hot topic in environmental research, biochar and its properties have been mainly investigated from the perspectives of feedstock type and pyrolysis temperature. Few studies have explored the effect of particle size on biochar properties.Even when the effect of particle size on crop efficiency is recognized, there is a lack of corresponding data and analysis.2–7 Therefore, we thoroughly analyzed (proximate and ultimate analysis, SEM, XRD, Raman spectroscopy) four particle size fractions (< 0.5, 0.5–2, 2–5, > 5 mm) of high-temperature biochar from a gasification power plant, the sizes reflecting those of biochar actually used in agriculture. The < 0.5 mm fraction was significantly different in terms of carbon structure, and carbon and ash content. Consequently, pH, electric conductivity and heavy metal content also differed greatly. The corresponding results for the other particle fractions were broadly similar to each other. Interestingly, for all fractions, the porosity and H/C ratio were independent of particle size, meaning that, regardless of size, the investigated biochar fractions are equally stable in soil. The 0.5–2 mm fraction was then selected to be used in different industrial or agricultural processes such as the anaerobic digestion of wastewater or livestock feeding. The effect of biochar on these processes is currently under investigation, providing only initial data so far.
Klíčová slova:
biochar; particle size on biochar; high-temperature biochar
Plné texty jsou dostupné v digitálním repozitáři NUŠL
Properties and use of high-temperature biochar
Despite being a hot topic in environmental research, biochar and its properties have been mainly investigated from the perspectives of feedstock type and pyrolysis temperature. Few studies have ...
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