No (14176)
Yes (2008)
Number of found documents:
16184
Published from
to
Analýza malty z 19. století
Bauerová, Pavla; Frankeová, Dita; Slížková, Zuzana; Vondráčková, Michaela
2023 - Czech
Chemické a mineralogické složení pojiva a plniva malty pomocí elektronové mikroskopie (SEM-EDS) a termické analýzy Chemical and mineralogical composition of the binder and the aggregates of the mortar, using SEM-EDS and thermal analysis
Keywords:
SEM-EDS analysis; historic mortar; hydraulic lime; decalcification; carbonatization
Available at various institutes of the ASCR
Analýza malty z 19. století
Chemické a mineralogické složení pojiva a plniva malty pomocí elektronové mikroskopie (SEM-EDS) a termické analýzy...
2TDK Railway, profile P18. Datings. Final Report.
Bosák, Pavel; Zupan Hajna, N.; Hercman, H.; Horáček, I.; Kdýr, Šimon; Kogovšek, B.
2023 - English
Samples for datings were taken in the railway construction (2TDK) near village of Divača, Classical Karst on October 12, 2021: (1) vertebrate bones in cave 2TDK – 002 at the profile P18, cave entrance appeared during the construction operations on cleaned karst surface in a wall of karst depression. Samples of mammal bones and gastropods were collected in situ on cave bottom, and (2) pieces of speleothems occurring in non in situ position on artificially planated surface near the cave opening were collected. U-series: no numerical date was obtained as geochemistry of sample indicate open system, probably due to recrystallization of sample in soil cover. Paleomagnetism: The transition of N- and R-polarized samples cannot be identified more precisely as U-series radiometric dating yielded no numerical results. The transition easily can represent Brunhes/Matuyama boundary (at 773 ka) as well as any of older such transitions (e. g., base of Jaramillo, base of Olduvai). In any case the speleothem grew in a closed cave space with roof, probably as flowstone (inclusion of red soils above the base) and later as baldachin on eroded allogenic fill of the paleocave. Vertebrate paleontology: bone remains of small and larger vertebrates represent subrecent to Holocene species. Sorex alpinus represents the species quite rare in fossil record, but recetly limited to variegated woodland habitats with high surface humidity. A chamois Rupicapra rupicapra represents a resident species present in Slovenia throughout all stages of a glacial cycle, recently restricted to mountain habitats.
Keywords:
Divača Karst; unroofed cave; speleothem; U-Th dating; paleomagnetism; zoopaleontology
Available at various institutes of the ASCR
2TDK Railway, profile P18. Datings. Final Report.
Samples for datings were taken in the railway construction (2TDK) near village of Divača, Classical Karst on October 12, 2021: (1) vertebrate bones in cave 2TDK – 002 at the profile P18, cave entrance ...
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 ...
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 ...
GA 19-07635S: Outputs and Results
Rehák, Branislav
2023 - English
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.
Keywords:
multi-agent systems; nonlinear multi-agent systems; synchronization
Fulltext is available at external website.
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 ...
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.\n
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 ...
Spherical basis function approximation with particular trend functions
Segeth, Karel
2023 - English
The paper is concerned with the measurement of scalar physical quantities at nodes on the $(d-1)$-dimensional unit sphere surface in the hbox{$d$-dimensional} Euclidean space and the spherical RBF interpolation of the data obtained. In particular, we consider $d=3$. We employ an inverse multiquadric as the radial basis function and the corresponding trend is a polynomial of degree 2 defined in Cartesian coordinates. We prove the existence of the interpolation formula of the type considered. The formula can be useful in the interpretation of many physical measurements. We show an example concerned with the measurement of anisotropy of magnetic susceptibility having extensive applications in geosciences and present numerical difficulties connected with the high condition number of the matrix of the system defining the interpolation.
Keywords:
spherical interpolation; spherical radial basis function; inverse multiquadric
Available in digital repository of the ASCR
Spherical basis function approximation with particular trend functions
The paper is concerned with the measurement of scalar physical quantities at nodes on the $(d-1)$-dimensional unit sphere surface in the hbox{$d$-dimensional} Euclidean space and the spherical RBF ...
Semantic segmentation using support vector machine classifier
Pecha, Marek; Langford, Z.; Horák, David; Tran Mills, R.
2023 - English
This paper deals with wildfire identification in the Alaska regions as a semantic segmentation task using support vector machine classifiers. Instead of colour information represented by means of BGR channels, we proceed with a normalized reflectance over 152 days so that such time series is assigned to each pixel. We compare models associated with $\mathcal{l}1$-loss and $\mathcal{l}2$-loss functions and stopping criteria based on a projected gradient and duality gap in the presented benchmarks.
Keywords:
wildfire identification; semantic segmentation; support vector machines; distributed training
Fulltext is available at external website.
Semantic segmentation using support vector machine classifier
This paper deals with wildfire identification in the Alaska regions as a semantic segmentation task using support vector machine classifiers. Instead of colour information represented by means of BGR ...
Estimation of EDZ zones in great depths by elastic-plastic models
Sysala, Stanislav
2023 - English
This contribution is devoted to modeling damage zones caused by the excavation of tunnels and boreholes (EDZ zones) in connection with the issue of deep storage of spent nuclear fuel in crystalline rocks. In particular, elastic-plastic models with Mohr-Coulomb or Hoek-Brown yield criteria are considered. Selected details of the numerical solution to the corresponding problems are mentioned. Possibilities of elastic and elastic-plastic approaches are illustrated by a numerical example.
Keywords:
tunnel stability; EDZ zones; elasto-plasticity; finite element method
Fulltext is available at external website.
Estimation of EDZ zones in great depths by elastic-plastic models
This contribution is devoted to modeling damage zones caused by the excavation of tunnels and boreholes (EDZ zones) in connection with the issue of deep storage of spent nuclear fuel in crystalline ...
Bohl-Marek decomposition applied to a class of biochemical networks with conservation properties
Papáček, Štěpán; Matonoha, Ctirad; Duintjer Tebbens, Jurjen
2023 - English
This study presents an application of one special technique, further called as Bohl-Marek decomposition, related to the mathematical modeling of biochemical networks with mass conservation properties. We continue in direction of papers devoted to inverse problems of parameter estimation for mathematical models describing the drug-induced enzyme production networks [3]. However, being aware of the complexity of general physiologically based pharmacokinetic (PBPK) models, here we focus on the case of enzyme-catalyzed reactions with a substrate transport chain [5]. Although our ultimate goal is to develop a reliable method for fitting the model parameters to given experimental data, here we study certain numerical issues within the framework of optimal experimental design [6]. Before starting an experiment on a real biochemical network, we formulate an optimization problem aiming to maximize the information content of the corresponding experiment. For the above-sketched optimization problem, the computational costs related to the two formulations of the same biochemical network, being (i) the classical formulation x˙(t) = Ax(t) + b(t) and (ii) the 'quasi-linear' Bohl-Marek formulation x˙M(t) = M(x(t)) xM(t), can be determined and compared.
Keywords:
Mathematical modeling; Biochemical network; Pharmacokinetic (PBPK) models
Fulltext is available at external website.
Bohl-Marek decomposition applied to a class of biochemical networks with conservation properties
This study presents an application of one special technique, further called as Bohl-Marek decomposition, related to the mathematical modeling of biochemical networks with mass conservation properties. ...
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