No (821)
Yes (151)
Used filters
(2)
Number of found documents:
972
Published from
to
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 ...
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 ...
Determination of the initial stress tensor from deformation of underground opening-theoretical background and applications
Malík, Josef; Kolcun, Alexej
2023 - English
In this paper a method for the detection of initial stress tensor is proposed. The method is based on measuring distances between some pairs of points located on the wall of underground opening in the excavation process. This methods is based on the solution of eighteen auxiliary problems in the theory of elasticity with force boundary conditions. The optimal location of the pairs of points on the wall of underground work is studied. The pairs must be located so that the condition number of a certain matrix has the minimal value, which guarantees a reliable estimation of initial stress tensor.
Keywords:
initial stress tensor; first boundary value problem of the theory of elasticity; condition number of matrices
Fulltext is available at external website.
Determination of the initial stress tensor from deformation of underground opening-theoretical background and applications
In this paper a method for the detection of initial stress tensor is proposed. The method is based on measuring distances between some pairs of points located on the wall of underground opening in the ...
Reduced basis solver for stochastic Galerkin formulation of Darcy flow with uncertain material parameters
Béreš, Michal
2023 - English
In this contribution, we present a solution to the stochastic Galerkin (SG) matrix equations coming from the Darcy flow problem with uncertain material coefficients in the separable form. The SG system of equations is kept in the compressed tensor form and its solution is a very challenging task. Here, we present the reduced basis (RB) method as a solver which looks for a low-rank representation of the solution. The construction of the RB consists of iterative expanding of the basis using Monte Carlo sampling. We discuss the setting of the sampling procedure and an efficient solution of multiple similar systems emerging during the sampling procedure using deflation. We conclude with a demonstration of the use of SG solution for forward uncertainty quantification.
Keywords:
stochastic Galerkin method; reduced basis method; Monte Carlo method; deflated conjugate gradient method
Fulltext is available at external website.
Reduced basis solver for stochastic Galerkin formulation of Darcy flow with uncertain material parameters
In this contribution, we present a solution to the stochastic Galerkin (SG) matrix equations coming from the Darcy flow problem with uncertain material coefficients in the separable form. The SG ...
Numerical realization of the Bayesian inversion accelerated using surrogate models
Bérešová, Simona
2023 - English
The Bayesian inversion is a natural approach to the solution of inverse problems based on uncertain observed data. The result of such an inverse problem is the posterior distribution of unknown parameters. This paper deals with the numerical realization of the Bayesian inversion focusing on problems governed by computationally expensive forward models such as numerical solutions of partial differential equations. Samples from the posterior distribution are generated using the Markov chain Monte Carlo (MCMC) methods accelerated with surrogate models. A surrogate model is understood as an approximation of the forward model which should be computationally much cheaper. The target distribution is not fully replaced by its approximation. Therefore, samples from the exact posterior distribution are provided. In addition, non-intrusive surrogate models can be updated during the sampling process resulting in an adaptive MCMC method. The use of the surrogate models significantly reduces the number of evaluations of the forward model needed for a reliable description of the posterior distribution. Described sampling procedures are implemented in the form of a Python package.
Keywords:
Bayesian inversion; delayed-acceptance Metropolis-Hastings; Markov chain Monte Carlo; surrogate model
Fulltext is available at external website.
Numerical realization of the Bayesian inversion accelerated using surrogate models
The Bayesian inversion is a natural approach to the solution of inverse problems based on uncertain observed data. The result of such an inverse problem is the posterior distribution of unknown ...
Současný stav geofyzikálních výzkumů a průzkumů v České republice
Kaláb, Zdeněk
2022 - Czech
Základní výzkum fyzikálních polí Země je v ČR řešen výzkumnou infrastrukturou CzechGeo/EPOS, což je ucelený systém pozorování geofyzikálních polí provozovaný geovědními institucemi České republiky. CzechGeo/EPOS je distribuovaná, vícevrstvá, mnohaoborová infrastruktura založená na sběru a poskytování dat z geofyzikálních monitorovacích sítí. V oblasti průzkumných geofyzikálních prací je patrně největší akcí průzkum potenciálních lokalit pro hlubinné úložiště jaderného odpadu. Nejedná se pouze o průzkum na potenciálních lokalitách, ale také aktivity prováděné v podzemním výzkumném pracovišti Bukov. Jedním z velkých úkolů, který na užitou geofyziku v krátké budoucnosti čeká, je podíl na průzkumech pro vysokorychlostní železniční trať. Aplikace geofyzikálních metod ale pronikají stále více do dalších oborů.\n\n The basic research of the Earth's physical fields in the Czech Republic is solved by the research infrastructure CzechGeo/EPOS, which is a comprehensive system for observing geophysical fields operated by geoscience institutions in the Czech Republic. CzechGeo/EPOS is distributed multilayer research infrastructure based on acquisition and distribution of data from geophysical monitoring networks. In the area of exploratory geophysical works, the survey of potential sites for the deep repository of nuclear waste is probably the biggest topic. This is not only a survey of potential sites, but also activities at the Bukov underground laboratory. One of the major challenges facing applied geophysics in the near future is to participate in surveys for the high-speed railway line. Applications of geophysical methods are increasingly penetrating also other fields.\n
Keywords:
geophysics; CzechGeo/EPOS; deep repository of nuclear waste; Bukov Underground Research Facility; geophysical survey
Available on request at various institutes of the ASCR
Současný stav geofyzikálních výzkumů a průzkumů v České republice
Základní výzkum fyzikálních polí Země je v ČR řešen výzkumnou infrastrukturou CzechGeo/EPOS, což je ucelený systém pozorování geofyzikálních polí provozovaný geovědními institucemi České republiky. ...
Viewpoint geosites and their potential for geoeducation and geotourism
Kubalíková, Lucie; Kirchner, Karel; Kuda, František
2022 - English
Viewpoint geosites are locations which allow observation of the surrounding landscape and comprehension of geodiversity (or Earth history recorded in rocks, structures and landforms) visible from this locality. The sites themselves don‘t have to be attractive from the Earth-sciences point of view, so they may be both natural (e.g. rock outcrops, mountain tops) and man-made objects (e.g. watchtowers, view terraces). These sites represent a very important resource for geotourism and geoeducation as they allow understand landscape, its history and relationships between its components. In this paper, we present examples of viewpoints from Podyjí National Park (both natural and man-made structures) that allow to observe geodiversity of the area. For an effective management and rational use of these specific and important sites, it is necessary to identify their characteristics and potential, so the guidelines for inventorying and method for assessment their potential are proposed. These procedures can contribute to the development of geotourist and geoeducational activities and above all, they enable better understanding of geodiversity’s position within landscape and justify its conservation and sustainable use.
Keywords:
geodiversity; inventory; assessment; landscape; viewshade analysis
Fulltext is available at external website.
Viewpoint geosites and their potential for geoeducation and geotourism
Viewpoint geosites are locations which allow observation of the surrounding landscape and comprehension of geodiversity (or Earth history recorded in rocks, structures and landforms) visible from this ...
Landscape photography in the research of landscape change
Skokanová, H.; Halas, Petr; Koutecký, T.; Kallabová, Eva; Havlíček, M.; Slach, T.
2022 - English
The paper presents partial results of “entering” landscape photography, which can be considered as a complementary method for the research of landscape changes. Unlike the usual assessment of landscape changes using cartographic and other archival sources, old landscape photographs can contribute to the deeper knowledge of the local specifics of the examined places or supplement the conventional procedures. Thanks to the ongoing project, supported by the Technology Agency of the Czech Republic (TL02000222), we documented changes in photographic shots of various landscapes in the 20th century. We also added information about environment, vegetation, and geography and photo documentation of the details of the researched shot. This creates a comprehensive output for each old landscape photograph. Such processed photographs have been presented at exhibitions in museums and galleries. Furthermore, they will be available to municipalities and public at a web page created as a tool to support public recreation. Here we present some examples from the Bohemian-Moravian Highlands. They show four types of landscape changes: 1) afforestation and overgrowth bywoody vegetation, 2) changes in the agricultural landscape, 3) loss of the grazing landscape, and 4) changes related to watercourses.\n
Keywords:
photographic shots; landscape structure changes; Bohemian-Moravian Highlands; vegetation change; public recreation
Fulltext is available at external website.
Landscape photography in the research of landscape change
The paper presents partial results of “entering” landscape photography, which can be considered as a complementary method for the research of landscape changes. Unlike the usual assessment of ...
Užití pružně-plastických modelů při odhadování zón poškození způsobených ražbou hlubinných tunelů
Sysala, Stanislav
2022 - Czech
Příspěvek se věnuje kontinuálnímu modelování zón poškození způsobených ražbou tunelů a vrtů v souvislosti s problematikou hlubinného ukládání vyhořelého jaderného paliva v krystalických\nhorninách. Pro jednoduchost jsou uvažovány a porovnávány pružné a pružně-plastické přístupy k modelování na základě Mohr-Coulombova nebo Hoek-Brownova kritéria poškození. Pro implementaci byly vytvořeny vlastní kódy v Matlabu a Pythonu s inovativními prvky. The paper deals with the continuous modelling of damage zones caused by excavation of tunnels and boreholes in connection with deep repository of spent nuclear fuel in crystalline rocks. For simplicity, elastic and elastic-plastic modelling approaches based on Mohr-Coulomb or Hoek-Brown failure criteria are presented and compared. For the implementation, proper codes were created in Matlab and Python with innovative elements.
Keywords:
stability of deep tunnels; EDZ zones; elasticity; plasticity; finite element method
Available on request at various institutes of the ASCR
Užití pružně-plastických modelů při odhadování zón poškození způsobených ražbou hlubinných tunelů
Příspěvek se věnuje kontinuálnímu modelování zón poškození způsobených ražbou tunelů a vrtů v souvislosti s problematikou hlubinného ukládání vyhořelého jaderného paliva v krystalických\nhorninách. ...
Polycentric urban forms: The relevance of scale for metropolitan and city planning
Malý, Jiří; Krejčí, Tomáš
2021 - English
The paper deals with the importance of scale in metropolitan and urban planning, in connection with the promoted and often applied concept of polycentric development. Although the normative conceptualization of polycentricity to some extent reflects the multi-scalar dimension, the operationalization of the concept encounters a number of limitations and fuzzy meanings that result from different scales of analysis and interpretation. Using the Czech context of planning practice, the negligence of the importance of overlapping geographical scales and limits of binding spatial planning materials is documented. The dependence of polycentricity on the scale has consequences both for the analytical evaluation of the spatial situation of the settlement system and for the subsequent interpretation of the results and the setting of further development strategies.\n
Keywords:
polycentricity; scale; metropolitan planning; urban planning
Fulltext is available at external website.
Polycentric urban forms: The relevance of scale for metropolitan and city planning
The paper deals with the importance of scale in metropolitan and urban planning, in connection with the promoted and often applied concept of polycentric development. Although the normative ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases