Number of found documents: 2086
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Deep learning methods for the acoustic emission methods to evaluate an onset of plastic straining
Parma, Slavomír; Kovanda, Martin; Chlada, Milan; Štefan, Jan; Kober, Jan; Feigenbaum, H. P.; Plešek, Jiří
2023 - English
Development of phenomenological plasticity models, hardening rules, and plasticity theories relies on experimental data of plastic straining. The experimental data are usually measured as the stress–strain response of the material being loaded and do not provide any clues or information about the local response of\nmaterial. In this paper, we analyze the plastic deformation of the material using the acoustic emission method and current state-of-the-art neural network models such as the InceptionTime architecture. Keywords: metal plasticity; strain hardening; acoustic emission; neural networks Fulltext is available at external website.
Deep learning methods for the acoustic emission methods to evaluate an onset of plastic straining

Development of phenomenological plasticity models, hardening rules, and plasticity theories relies on experimental data of plastic straining. The experimental data are usually measured as the ...

Parma, Slavomír; Kovanda, Martin; Chlada, Milan; Štefan, Jan; Kober, Jan; Feigenbaum, H. P.; Plešek, Jiří
Ústav termomechaniky, 2023

Model order reduction for particle-laden flows: systems with rotations and discrete transport operators
Kovárnová, A.; Isoz, Martin
2023 - English
In the present work, we concentrate on particle-laden flows as an example of industry-relevant transport-dominated systems. Our previously-developed framework for data-driven model order reduction (MOR) of such systems, the shifted proper orthogonal decomposition with interpolation via artificial neural networks, is further extended by improving the handling of general transport operators. First, even with intrusive MOR approaches, the underlying numerical solvers can provide only discrete realizations of transports linked to the movement of individual particles in the system. On the other hand, our MOR methodology requires continuous transport operators. Thus, the original framework was extended by the possibility to reconstruct continuous approximations of known discrete transports via another artificial neural network. Second, the treatment of rotation-comprising transports was significantly improved. Keywords: model order reduction; shifted POD; artificial neural networks; CFD-DEM; Open- FOAM Fulltext is available at external website.
Model order reduction for particle-laden flows: systems with rotations and discrete transport operators

In the present work, we concentrate on particle-laden flows as an example of industry-relevant transport-dominated systems. Our previously-developed framework for data-driven model order reduction ...

Kovárnová, A.; Isoz, Martin
Ústav termomechaniky, 2023

Underground Spaces In Bosonožský Hájek Nature Reserve And Their Geoeducation Importance
Kirchner, Karel; Kuda, František; Baldík, V.; Kubalíková, Lucie
2023 - English
Bosonožský hájek Natural Reserve (Brno, South Moravia) is a very important site from the Earth Science point of view, however, its geodiversity values have been rather overlooked and omitted in the past (the object of legal protection is the occurrence of well-preserved forest ecosystems and endangered species). In the last decades, a series of field work and geophysical measurements has been carried out and the Earth Science phenomena have been identified and described here. These are represented by a dense network of gullies that developed in Pleistocene loess and that are both of natural and anthropogenic origin (some gullies probably developed along the old paths) and specific underground spaces (so called dugouts). Until now, the dugouts in South Moravia have been investigated mainly by archaeologists and those in Bosonožský hájek NR have not been described in detail yet. This brief contribution brings new information about three underground landforms and their possible relationship to the age and development of the gullies. The possibility of different interpretations of the origin of these specific landforms can be considered an opportunity in the field of Earth Science (geosciences) education and as an interesting complement of tourist and recreational activities on site. Keywords: gully network; loess; dugouts; Earth Science education Fulltext is available at external website.
Underground Spaces In Bosonožský Hájek Nature Reserve And Their Geoeducation Importance

Bosonožský hájek Natural Reserve (Brno, South Moravia) is a very important site from the Earth Science point of view, however, its geodiversity values have been rather overlooked and omitted in the ...

Kirchner, Karel; Kuda, František; Baldík, V.; Kubalíková, Lucie
Ústav geoniky, 2023

Dynamics of a cantilever beam with piezoelectric sensor: Finite element modeling
Cimrman, Robert; Kolman, Radek; Musil, Ladislav; Kotek, Vojtěch; Kylar, Jaromír
2023 - English
An elastodynamical model of a cantilever beam coupled with a piezoelectric sensor is introduced and its discretization using the finite element method is presented. The mathematical model includes additional terms that enforce the floating potential boundary condition for keeping a constant charge on an electrode of the sensor. The behaviour of the model is illustrated using a numerical example corresponding to an experimental setup, where vibrations of the beam and the potential on the sensor are measured. Keywords: finite element method; piezo-electricity; floating potential; dynamic simulation Fulltext is available at external website.
Dynamics of a cantilever beam with piezoelectric sensor: Finite element modeling

An elastodynamical model of a cantilever beam coupled with a piezoelectric sensor is introduced and its discretization using the finite element method is presented. The mathematical model includes ...

Cimrman, Robert; Kolman, Radek; Musil, Ladislav; Kotek, Vojtěch; Kylar, Jaromír
Ústav termomechaniky, 2023

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 ...

Malík, Josef; Kolcun, Alexej
Ústav geoniky, 2023

Hydrolgoie malého povodí 2023
Hnilicová, Soňa; Tesař, Miroslav
2023 - Czech
Sborník obsahuje plné texty vědeckých článků. Příspěvky neprošly jazykovou kontrolou a za obsah odpovídají autoři článků. Články byly připraveny jako příspěvky pro konferenci „Hydrologie malého povodí 2023“ s tématickými okruhy: 1. Globální vlivy a změny v režimu vodních zdrojů v malém povodí; 2. Komplexní monitoring a bilance zásob vody v malých povodích; 3. Hydrologické extrémy (přívalové povodně; sucho – typy a hodnocení); 4. Vliv vegatačního krytu a způsobu využití povodí na vodní režim; 5. Transportní procesy v půdě a vliv hydrofobie povrchové vrstvy na ně; 6. Hydrologické modelování; nejistoty v hydrologickém modelování; 7. Látkové toky v malém povodí a eutrofizace povrchových vod; 8. Malá povodí v horský oblastech (usazené srážky, akumulace a tání sněhu, atd.); 9. Nové metody, techniky a přístrojové vybavení v hydrologii a hydroekologii.\n The book is a collection of scientific contributions to the Conference "Hydrology of small basins". The conference topics were: 1. Changes in the regime of water resources in small basins; 2. Complex monitoring a and water storage balance in small basins; 3. Hydrological extremes (flash floods, drought); 4. Effect of land use and land cover on water balance; 5. Hydrophobicity and transportation processes in soil; 6. Hydrological modelling und uncertainties; 7. Biogeochemical fluxes in a small watershed and eutrophication of surface waters; 8. Mountainous experimental small basins (deposited precipitation, snow regime, …); 9. New methods, techniques and instrumentation in hydrology and hydroecology.\n Keywords: experimental hydrology; hydrological monitoring; subsurface hydrology; small basin; water balance; hydrological modelling Fulltext is available at external website.
Hydrolgoie malého povodí 2023

Sborník obsahuje plné texty vědeckých článků. Příspěvky neprošly jazykovou kontrolou a za obsah odpovídají autoři článků. Články byly připraveny jako příspěvky pro konferenci „Hydrologie malého povodí ...

Hnilicová, Soňa; Tesař, Miroslav
Ústav pro hydrodynamiku, 2023

Vývoj nástrojů pro minimalizaci rizik kontaminace ovzduší respirabilními azbestovými vlákny uvolňovanými lidskou činností z horninového prostředí – souhrnná výzkumná zpráva o průběhu a výsledcích řešení projektu
Vavro, Leona; Vavro, Martin; Daněk, T.; Kajzar, Vlastimil; Drozdová, J.; Raclavský, K.; Kubina, Lukáš
2023 - Czech
Souhrnná výzkumná zpráva přináší zhodnocení postupu a výsledků projektu SS01010257 - Vývoj nástrojů pro minimalizaci rizika kontaminace ovzduší respirabilními azbestovými vlákny uvolňovanými lidskou činností z horninového prostředí (AZROCK). Řešený projekt měl dva hlavní cíle. Prvním bylo vytvoření dvou metodických návodů, a to jednak pro odběr vzorků hornin a kameniva s možným obsahem přirozeně se vyskytujících azbestů a jednak pro následnou analýzu přítomnosti azbestových vláken v odebraných vzorcích. Dále si projekt stanovil za cíl tvorbu specializované mapy rizika výskytu azbestu v horninovém prostředí v České republice a internetového znalostního portálu azbestů. Podstatná část řešení projektu byla založena na odběru vzorků hornin a kameniva na téměř stovce vytipovaných lokalit po celé České republice a jejich následném vyhodnocení zvoleným a ověřeným souborem analytických metod. Podobné informace o výskytu azbestu v horninovém prostředí České republiky nebyly dosud zájemcům z řad odborné i laické veřejnosti k dispozici. The summary research report provides an evaluation of the procedure and results of the project SS01010257 - Development of tools to minimise the risks of air contamination by respirable asbestos fibres released from the rock environment by human activities (AZROCK). The solved project had two main objectives. The first one was the creation of two methodical instructions, both for the rock and aggregate sampling with a possible naturally occurring asbestos content and for the subsequent analysis of the presence of asbestos fibers in the samples taken. Furthermore, the project set itself the goal of creating: (1) a specialized map of the risk of asbestos occurrence in the rock environment in the Czech Republic and (2) a web knowledge portal of asbestos. A substantial part of the project solution was based on the collection of samples of rocks and aggregates at almost a hundred selected sites throughout the Czech Republic and their subsequent evaluation using a selected and verified set of analytical methods. Similar information on the occurrence of asbestos in the rock environment of the Czech Republic has not yet been available to interested professionals and the non-specialist public. Keywords: naturally occuring asbestos; rocks; aggregate; sampling; analysis; Czech Republic Fulltext is available at external website.
Vývoj nástrojů pro minimalizaci rizik kontaminace ovzduší respirabilními azbestovými vlákny uvolňovanými lidskou činností z horninového prostředí – souhrnná výzkumná zpráva o průběhu a výsledcích řešení projektu

Souhrnná výzkumná zpráva přináší zhodnocení postupu a výsledků projektu SS01010257 - Vývoj nástrojů pro minimalizaci rizika kontaminace ovzduší respirabilními azbestovými vlákny uvolňovanými lidskou ...

Vavro, Leona; Vavro, Martin; Daněk, T.; Kajzar, Vlastimil; Drozdová, J.; Raclavský, K.; Kubina, Lukáš
Ústav geoniky, 2023

Vhodné restaurátorské postupy pro zachování stop opracování kamene. Využití blízké fotogrammetrie k ohodnocení vhodnosti restaurátorských postupů
Cihla, Michal; Frommeltová, E.; Hodač, J.; Kovářová, K.; Pavelka, K.; Panáček, M.; Valach, Jaroslav
2023 - Czech
Tento památkový postup je výsledkem výzkumného projektu s názvem „Topografie povrchu kamene a její aplikace v oblasti restaurování kamenných prvků“ č. DG20P02OVV021, podpořeném Ministerstvem kultury ČR. Cílem památkového postupu bylo ověření vhodnosti a použitelnosti přesných měřičských metod za účelem zhodnocení míry restaurátorského zásahu v oblasti stop po opracování povrchu kamene. Nástrojem pro hodnocení změn topografie kamenných povrchů nesoucích stopy po opracování byla zvolena metoda blízké fotogrammetrie. This preservation procedure is the result of the research project entitled „Building stone surface topography and its application in the field of stone features restoration“ No.DG20P02OVV021, supported by the Ministry of Culture of the Czech Republic. The aim of the preservation procedure was to verify the suitability and applicability of precise measuring methods in order to assess the degree of restoration intervention in the area of traces of stone surface working. The method of close-range photogrammetry was chosen as a tool to evaluate the changes in the topography of stone surfaces bearing traces of working. Keywords: stone topography; photogrammetry; stonemason’s tools traces; restoration; conservation; stone; monuments; building stone Fulltext is available at external website.
Vhodné restaurátorské postupy pro zachování stop opracování kamene. Využití blízké fotogrammetrie k ohodnocení vhodnosti restaurátorských postupů

Tento památkový postup je výsledkem výzkumného projektu s názvem „Topografie povrchu kamene a její aplikace v oblasti restaurování kamenných prvků“ č. DG20P02OVV021, podpořeném Ministerstvem kultury ...

Cihla, Michal; Frommeltová, E.; Hodač, J.; Kovářová, K.; Pavelka, K.; Panáček, M.; Valach, Jaroslav
Ústav teoretické a aplikované mechaniky, 2023

Good vs. Bad Volatility in Major Cryptocurrencies: The Dichotomy and Drivers of Connectedness
Šíla, Jan; Kočenda, Evžen; Kukačka, Jiří; Krištoufek, Ladislav
2023 - English
Cryptocurrencies exhibit unique statistical and dynamic properties compared to those of traditional financial assets, making the study of their volatility crucial for portfolio managers and traders. We investigate the volatility connectedness dynamics of a representative set of eight major crypto assets. Methodologically, we decompose the measured volatility into positive and negative components and employ the time-varying parameters vector autoregression (TVP-VAR) framework to show distinct dynamics associated with market booms and downturns. The results suggest that crypto connectedness reflects important events and exhibits more variable and cyclical dynamics than those of traditional financial markets. Periods of extremely high or low connectedness are clearly linked to specific events in the crypto market and macroeconomic or monetary history. Furthermore, existing asymmetry from good and bad volatility indicates that information about market downturns spills over substantially faster than news about comparable market surges. Overall, the connectedness dynamics are predominantly driven by fundamental crypto factors, while the asymmetry measure also depends on macro factors such as the VIX index and the expected inflation. Keywords: Volatility; Dynamic connectedness; Asymmetric effects; Cryptocurrency Fulltext is available at external website.
Good vs. Bad Volatility in Major Cryptocurrencies: The Dichotomy and Drivers of Connectedness

Cryptocurrencies exhibit unique statistical and dynamic properties compared to those of traditional financial assets, making the study of their volatility crucial for portfolio managers and traders. ...

Šíla, Jan; Kočenda, Evžen; Kukačka, Jiří; Krištoufek, Ladislav
Ústav teorie informace a automatizace, 2023

Dynamics of a cantilever beam with piezoelectric sensor: Parameter identification
Cimrman, Robert; Kolman, Radek; Musil, Ladislav; Kotek, Vojtěch; Kylar, Jaromír
2023 - English
The piezoelectric materials are electroactive materials often applied for real-time sensing or structural health monitoring, both important research topics in dynamics. Mathematical models of such structures have to allow also for the external electrical circuits and contain several material parameters that need to be identified from experiments. We present a model of a simple experiment involving dynamics of a cantilever beam with an attached piezoelectric sensor excited by a suddenly removed weight. The external circuit can be taken into account as having either a finite or infinite resistance. We also outline the parameter identification procedure based on automatic differentiation and present the experimental and numerical results. Keywords: finite element method; piezo-electricity; floating potential; dynamic simulation; parameter identification Fulltext is available at external website.
Dynamics of a cantilever beam with piezoelectric sensor: Parameter identification

The piezoelectric materials are electroactive materials often applied for real-time sensing or structural health monitoring, both important research topics in dynamics. Mathematical models of such ...

Cimrman, Robert; Kolman, Radek; Musil, Ladislav; Kotek, Vojtěch; Kylar, Jaromír
Ústav termomechaniky, 2023

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