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From John Graunt to Adolphe Quetelet: on the Origins Of Demography
Kalina, Jan
2023 - English
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.
Keywords:
history of demography; history of statistics; probability theory; moral statistics; mortality tables
Fulltext is available at external website.
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 - English
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.
Keywords:
accretion discs; black holes; active galactic nuclei
Fulltext is available at external website.
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 ...
Infants' learning of novel segments is modulated by prosody
Chládková, Kateřina; Podlipský, V.J.; Nudga, Natalia; Paillereau, Nikola; Kynčlová, Kateřina; Šimáčková, Š.
2023 - English
Young infants recognize atypical realisations of native-language speech. Later they learn words better from native-accented talkers. However, 6-month-olds preferentially listen to unfamiliar speech. We tested whether the learning of new vowels matches 6-month-olds’ listening preferences, being more effective from nonnative-accented speech. We exposed Czech six-month-olds to delexicalised utterances with consonants replaced by [f] and vowels by 405 tokens sampled from a bimodal [ɛ]-[æ] distribution, a contrast absent from Czech, and with either native or atypical rhythm. Discrimination of [ɛ]-[æ] was then tested in an alternating/non-alternating paradigm. Longer first-look duration to non-alternating than to alternating trials – indicating a learning effect – was found in infants familiarised with the novel contrast in atypical rhythm, such effect was not\ndetected after familiarisation with native rhythm. Six-month-olds thus more effectively exploit distributional information about novel vowels from non-native rhythm, which matches their previously reported preferences for listening to novel over familiar accents.
Keywords:
distributional learning; selective learning; non-native rhythm; vowels; infancy
Available on request at various institutes of the ASCR
Infants' learning of novel segments is modulated by prosody
Young infants recognize atypical realisations of native-language speech. Later they learn words better from native-accented talkers. However, 6-month-olds preferentially listen to unfamiliar speech. ...
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 - English
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.
Keywords:
Dynamical system; Singular perturbation; Averaging; Parameter estimation; Slow-fast decomposition; Damped oscillations
Fulltext is available at external website.
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 ...
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 - English
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.
Keywords:
large eddy simulation; wind tunnel; atmospheric boundary layer; PALM model; turbulence
Fulltext is available at external website.
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 ...
Room temperature ethanol detection using carbon materials
Kočí, Michal
2023 - English
Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and extraordinary physical and chemical properties, preferable for many different applications, including sensor devices. This work focuses on responses of various sensing layers (NCD with hydrogen termination (H-NCD), graphene oxide (GO), reduced graphene oxide (rGO), thiol-functionalized graphene oxide (GO-SH) and their hybrid structures to ethanol vapor with concentrations up to 100 ppm in synthetic air at room temperature. The measured parameters of the tested sensors, especially stability, reproducibility and regeneration, are compared and critically evaluated. The high sensitivity of tested sensors achieved at room temperature makes them very promising for monitoring ethanol vapor as well as other volatile substances (e.g., isopropyl-alcohol or acetone).
Keywords:
gas sensor; nanocrystalline diamond (NCD); graphene oxide (GO); reduced graphene oxide (rGO); thiol-functionalized graphene oxide (GO-SH)
Available at various institutes of the ASCR
Room temperature ethanol detection using carbon materials
Allotropic forms of carbon, in particular graphene oxide (GO) or nanocrystalline diamond (NCD), attracted the attention of many research groups due to their unique electronic structures and ...
Mechanical properties of basalt: a study on compressive loading at different strain rates using SHPB
Falta, J.; Krčmářová, N.; Fíla, T.; Vavro, Martin; Vavro, Leona
2023 - English
This article focuses on the mechanical properties of basalt in compressive loading at different strain-rates. The study employs advanced instrumentation for the evaluation of the results in dynamic conditions, while standard uni-axial loading device is used for evaluation in quasi-static conditions. Basalt specimens were subjected to four different loading-rates from 200–600 s−1 on which the stress-strain dependence was evaluated together with DIC analysis of crack initiation and disintegration process. Understanding the mechanical properties of basalt can provide insights for engineers and designers in creating structures that are durable and able to withstand different loading conditions. The findings of this study can have implications for a wide range of industries, including aerospace, automotive, and construction, among others.
Keywords:
SHPB; basalt; compressive loading; dynamic loading
Available at various institutes of the ASCR
Mechanical properties of basalt: a study on compressive loading at different strain rates using SHPB
This article focuses on the mechanical properties of basalt in compressive loading at different strain-rates. The study employs advanced instrumentation for the evaluation of the results in dynamic ...
Asynchronous time integration while achieving zero interface energy
Dvořák, Radim; Kolman, Radek; Falta, J.; Neühauserová, M.
2023 - English
This contribution deals with an asynchronous direct time integration of the finite-element model. The proposed method is applied to the phenomenon of wave propagation through an elastic linear continuum. The numerical model is partitioned into individual subdomains using the domain decomposition method by means of localized Lagrange multipliers. For each subdomain, different time discretizations are used. No restrictions for relation between subdomain’s time steps are imposed. The coupling of the subdomains is forced by an acceleration continuity condition. Additionally, we use the a posteriori technique to also provide the displacement and velocity continuity at the interfaces, and hence we obtain exact continuity of all three kinematic fields. The proposed method is experimentally validated using the modified SHPB (split Hopkinson pressure bar) setup.
Keywords:
finite element method; direct time integration; asynchronous integration; domain decomposition; localized lagrange multipliers
Available at various institutes of the ASCR
Asynchronous time integration while achieving zero interface energy
This contribution deals with an asynchronous direct time integration of the finite-element model. The proposed method is applied to the phenomenon of wave propagation through an elastic linear ...
Comparison of finite element simulation of tungsten nanoindentation with Berkovich and conical indenter
Fiala, L.; Ballo, I.; Kovář, J.; Fuis, Vladimír
2023 - English
Finite Element Method (FEM) was used to study the difference between using Berkovich and conical indenters in nanoindentation test of tungsten specimen. The study was aimed to determine the\nmodulus of elasticity of a tested specimen and how it changes with different indenter. The FEM analysis also revealed that the modulus of elasticity was sensitive to the dimensions of both specimen and the indenter for which were made several numerical calculations with different dimensions.
Keywords:
nanoindentation; FEM; Berkovich indenter; conical indenter; tungsten
Available at various institutes of the ASCR
Comparison of finite element simulation of tungsten nanoindentation with Berkovich and conical indenter
Finite Element Method (FEM) was used to study the difference between using Berkovich and conical indenters in nanoindentation test of tungsten specimen. The study was aimed to determine the\nmodulus ...
Ambiguity in Stochastic Optimization Problems with Nonlinear Dependence on a Probability Measure via Wasserstein Metric
Kaňková, Vlasta
2023 - English
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.
Keywords:
Stochastic optimization problems; static problems; empirical measure; point estimates; interval estimates; nonlinear dependence
Fulltext is available at external website.
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 ...
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