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Dynamics of surface water quality changes in model headwater areas of the Czech Republic
Fraindová, K.; Matoušková, M.; Kliment, Z.; Vlček, Lukáš; Vlach, V.; Šajnarová, L.
2023 - English
River headwaters have a high environmental value. Unfortunately, the biogeochemical processes in headwaters in context of different rainfall-runoff conditions and specific land cover have not been fully examined. This study focuses on changes in correlations of 16 biogeochemical parameters related to different types of rainfall-runoff events and land cover condition for eight headwater catchments in Central Europe. Multiple methods as linear regression, Spearman rank correlation, Principal Components Analysis and C/Q hysteresis loops revealed main relationships. Presence of peatlands and waterlogged spruce forests had decisive influence on the biogeochemistry (mainly for CODMn, humins, Fe, P-PO43− TP, and N-NO3−). The strongest positive correlation of organic matter (CODMn) and Fe is represented in a catchment with the largest area of damaged forest (70%), but with a smaller proportion of wetlands (8%). High flow rates influence the release of greater amounts of organic matter and N-NO3−.
Keywords:
headwater areas; organic matter; waterlogged areas; peatbogs; raifall-runoff events; water quality; electric conductivity
Fulltext is available at external website.
Dynamics of surface water quality changes in model headwater areas of the Czech Republic
River headwaters have a high environmental value. Unfortunately, the biogeochemical processes in headwaters in context of different rainfall-runoff conditions and specific land cover have not 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 ...
Metodologie dějin umění a výzkum 19. století v perspektivě pokroku
Petrasová, Taťána
2023 - Czech
Příspěvek zkoumá možnosti, které se otevřely v období 1981–1990 interdisciplinárnímu výzkumu historismu 19. století v tehdejším Československu, v souvislosti se založením tradice plzeňského sympozia. Z jedné strany badatelé sledovali aktuální myšlenky „umění a pokroku“, s nimiž vystoupil Ernst Gombrich (1971). Z opačné strany přicházeli zastánci myšlenky „vývojové racionality a iracionality“ jako zdroje myšlenkové i estetické autenticity děl 19. století, jako Rudolf Chadraba, Jiří Ševčík, Helena Lorenzová a Vladimír Macura. The paper analyses the possibilities that opened up in the period 1981–1990 for the interdisciplinary research of Historicism in the former Czechoslovakia, given by the founding tradition of the Pilsen symposia. On the one hand, the researchers followed the current ideas of “art and progress” dealt with Ernst Gombrich (1971). From the opposite side came supporters of the idea of “rationality and irrationality” of development as a source of intellectual and aesthetic authenticity of 19th century works, such as jako Rudolf Chadraba, Jiří Ševčík, Helena Lorenzová a Vladimír Macura.
Keywords:
methodology of art history; Ernst Gombrich; Rudolf Chadraba; Jiří Ševčík; Helena Lorenzová; Vladmír Macura; 19th century; Czech Lands
Available at various institutes of the ASCR
Metodologie dějin umění a výzkum 19. století v perspektivě pokroku
Příspěvek zkoumá možnosti, které se otevřely v období 1981–1990 interdisciplinárnímu výzkumu historismu 19. století v tehdejším Československu, v souvislosti se založením tradice plzeňského sympozia. ...
COMPUTER SIMULATION STUDY OF THE STABILITY OF UNDERACTUATED BIPEDAL ROBOT MODELS (motivated by Griffin and Grizzle, 2017)
Polach, P.; Anderle, Milan; Zezula, Pavel; Papáček, Štěpán
2023 - English
A key feature for bipedal walkers (robots and humans as well) is their stability or disturbance rejection defined as the ability to deal with unexpected disturbances. The paper by Griffin and Grizzle (2017) have significantly contributed to the shift from flat ground to slopes and steps when evaluating the walking efficiency of their robots. Similarly, in this contribution, based on the appropriate model of robot dynamics and control law, we examine the stability of walking-without-falling for different ground perturbations for a threelink compass gait walker. I.e., we perform the sensitivity analysis of the walking stability of underactuated bipedal walker with respect to certain disturbation using the alaska/MultibodyDynamics simulation tool.
Keywords:
Mechatronics; Bipedal robot; Multibody dynamics; Acrobot; Control applications
Fulltext is available at external website.
COMPUTER SIMULATION STUDY OF THE STABILITY OF UNDERACTUATED BIPEDAL ROBOT MODELS (motivated by Griffin and Grizzle, 2017)
A key feature for bipedal walkers (robots and humans as well) is their stability or disturbance rejection defined as the ability to deal with unexpected disturbances. The paper by Griffin and Grizzle ...
Ivan Borkovský. Archeolog mezi legendou, dvěma světovými válkami a dvěma totalitními režimy
Maříková-Kubková, Jana; Adámek, František
2023 - Czech
Archeolog Ivan Borkovský vedl více než čtyřicet let technicky a později i odborně výzkum Pražského hradu, vedle toho se věnoval desítkám dalších lokalit. Patří k nejvýraznějším osobnostem československé a české archeologie středověku. Byl kolegou a učitelem celé řady významných archeologů, historiků a architektů. Přesto v jeho osobním životě a v jeho osudech ve vypjatých obdobích 20. století jsou neznámé momenty. Ve vzpomínkových textech jeho žáků a kolegů se vyskytují příběhy, které se za téměř padesát let od jeho smrti staly legendami. Většina z nich se ale nezakládá na pravdě. Je otázkou, zda podnět k těmto příběhům dal Ivan Borkovský sám nebo zda vznikly později a jakou roli v nich sehrála osobnost vypravěče. Předkládaný text se věnuje především těmto zvratům v jeho životě a pokouší se archivním průzkumem potvrdit nebo vyvrátit často opakovaná cliché. V neposlední řadě je cílem práce připravit půdu pro komplexnější zpracování jeho odborného odkazu, které nebude možné bez pochopení úskalí, jež jeho život provázela. Archaeologist Ivan Borkovský led the technical and later professional research of Prague Castle for more than forty years, in addition to dozens of other sites. He is one of the most prominent personalities of Czechoslovak and Czech archaeology of the Middle Ages. He was a colleague and teacher of a number of prominent archaeologists, historians and architects. Yet there are unknown moments in his personal life and in his fate in the tense periods of the 20th century. In the memoirs of his students and colleagues, there are stories that have become legendary in the nearly fifty years since his death. But most of them are not based on truth. The question is whether Ivan Borkovský himself gave rise to these stories or whether they were written later and what role the personality of the narrator played in them. The presented text focuses on these twists and turns in his life and attempts to confirm or refute the oft-repeated clichés through archival research. Last but not least, the thesis aims to pave the way for a more comprehensive treatment of his scholarly legacy, which will not be possible without an understanding of the pitfalls that accompanied his life.
Keywords:
Ivan Borkovský; Prague Castle; Ukrainian immigration
Available at various institutes of the ASCR
Ivan Borkovský. Archeolog mezi legendou, dvěma světovými válkami a dvěma totalitními režimy
Archeolog Ivan Borkovský vedl více než čtyřicet let technicky a později i odborně výzkum Pražského hradu, vedle toho se věnoval desítkám dalších lokalit. Patří k nejvýraznějším osobnostem ...
Vizualizace záznamů v Bibliografii dějin Českých zemí. Od tištěných ročenek po moderní databázi
Hanelová, Věra
2023 - Czech
Příspěvek pojednává o vydávání tištěných bibliografických ročenek a vizualizaci záznamů v databázi Bibliografie dějin Českých zemí. Představuje nejen bibliografické záznamy, které jsou obohacovány o plné texty, ale také rejstříky (biografický, geografický, klíčových slov).
Keywords:
bibliographic records; bibliographic yearbooks; database; visualization
Available at various institutes of the ASCR
Vizualizace záznamů v Bibliografii dějin Českých zemí. Od tištěných ročenek po moderní databázi
Příspěvek pojednává o vydávání tištěných bibliografických ročenek a vizualizaci záznamů v databázi Bibliografie dějin Českých zemí. Představuje nejen bibliografické záznamy, které jsou obohacovány o ...
Annular Impinging Jets and an Active Control of Hysteretic Effects
Devani, Yogendrasasidhar; Antošová, Zuzana; Trávníček, Zdeněk
2023 - English
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling effects, eight synthetic jets were generated from the nozzle center body. The experiments cover Reynolds numbers 4000–10,000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A, B) were found under the same boundary conditions. For higher Re>9000, the hysteresis were not found.
Keywords:
annular jet; impinging jet; hysteresis
Available at various institutes of the ASCR
Annular Impinging Jets and an Active Control of Hysteretic Effects
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling ...
Souvislost mezi principem nejmenší akce a termodynamickou podmínkou stability
Maršík, František; Trávníček, Zdeněk; Antošová, Zuzana
2023 - English
The extended principle is formulated for a material point (M.P.) X, which has nonzero mass, temperature, and trajectory x(X,t). The Lagrangian of this variation principle is equal to the kinetic energy from which, the internal energy of the material point (which depends on the entropy) and the additional energy caused by the frictional force are subtracted. The relation between the inertial force and the entropy gradient is found and the gravitational force is completely replaced by the entropy gradient. Thanks to the mentioned properties of the total enthalpy, the Thermodynamic criterion of stability of the state of M.P., is formulated.
Keywords:
principle of the least action; thermodynamic stability condition; annular swirl flow
Fulltext is available at external website.
Souvislost mezi principem nejmenší akce a termodynamickou podmínkou stability
The extended principle is formulated for a material point (M.P.) X, which has nonzero mass, temperature, and trajectory x(X,t). The Lagrangian of this variation principle is equal to the kinetic ...
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