IPC-IOPC 2024: Abstract book
Bek, Jiří; Votočková Frojdová, Jana
2024 - anglický Klíčová slova: Palaeobotany; palynology; plants; spores Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. IPC-IOPC 2024: Abstract book

Bek, Jiří; Votočková Frojdová, Jana
Geologický ústav, 2024

Functional Tungsten-based thin films and their characterization
Košelová, Zuzana; Horáková, L.; Sobola, Dinara; Burda, Daniel; Knápek, Alexandr; Fohlerová, Z.
2024 - anglický Anodizing is a technique by which thin oxide layers can be formed on a surface. Thin oxide layers have been found to be useful in a variety of applications, including emitters of electrons. Tungsten is still a common choice for cold field emitters in commercial microscopy applications. Its suitable quality can be further improved by thin film deposition. Not only the emission characteristic can be improved, but also the emitter operating time can be extended. Tungsten oxide is known for its excellent resistance to corrosion and chemical attack due to its stable crystal structure and strong chemical bonds between tungsten and oxygen atoms. Many techniques with different advantages and disadvantages have been used for this purpose. Anodization was chosen for this work because of the controllable uniform coverage of the material and its easy availability without the need for expensive complex equipment. The anodizing process involves applying an electrical potential to tungsten while it is immersed in an electrolyte solution. This creates a thin layer of tungsten oxide on the surface of the metal. The thickness and properties of the resulting oxide layer can be controlled by adjusting the anodization conditions, such as the electrolyte solution, voltage, and the duration of the process. In this work, H3PO4 was used as the electrolyte to test whether these tungsten oxide layers would be useful for electron emitters, for use in electron guns and other devices that require high-quality electron emitters. The properties were evaluated using appropriate techniques. In general, anodization of tungsten to form thin layers of tungsten oxide layers is a promising technique for producing high quality electron emitters. Klíčová slova: cold-field emission; thin layer deposition; tungsten oxide; resonance enhanced tunneling; anodization Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Functional Tungsten-based thin films and their characterization

Anodizing is a technique by which thin oxide layers can be formed on a surface. Thin oxide layers have been found to be useful in a variety of applications, including emitters of electrons. Tungsten ...

Košelová, Zuzana; Horáková, L.; Sobola, Dinara; Burda, Daniel; Knápek, Alexandr; Fohlerová, Z.
Ústav přístrojové techniky, 2024

Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna; Bílek, Vojtěch; Haidl, Jan; Isoz, M.; Pivokonský, Martin
2024 - anglický Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models. Klíčová slova: flocculation tank; stirring; MRF; CFD; OpenFOAM Plné texty jsou dostupné v digitálním repozitáři Akademie Věd. Flow simulations approach for flocculation tanks

Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and ...

Idžakovičová, Kristýna; Bílek, Vojtěch; Haidl, Jan; Isoz, M.; Pivokonský, Martin
Ústav pro hydrodynamiku, 2024

EFFECT OF STEEL COMPOSITION ON ITS BEHAVIOUR IN THE LIQUID LEAD ENVIRONMENT
Pazderova, M.; Hojná, A.; Vít, J.; Hadraba, Hynek; Čižek, J.
2024 - anglický Ferritic-martensitic Eurofer-97 and oxide dispersion strengthened (ODS) Eurofer steels are potential candidates for structural applications in advanced nuclear reactors. Influence of scandium, yttrium, and aluminum addition was studied at 600 degrees C using 10-6 wt.% oxygen concentration. Microstructure and corrosion behaviour was evaluated after 500 h and 1000 h of exposure to liquid lead. Microscopical investigation identified oxidation, solution- based attack, and Pb penetration into the material. Addition of scandium and aluminum changed the mechanism of corrosion attack. Eurofer-97 was partially protected by outer oxide and inner oxidation and Pb penetration was found. In contrast ODS-Eurofer steels after 1000 h of exposure showed mainly inner oxidation and SBA including Pb penetration into the steel. The inner oxidation consisted of Pb+Cr-O and Cr-O+Al-O layers mixture. Degradation of ODS steel was significantly lower than Eurofer-97. It seems that the inner oxidation layer beneath the surface did not prevent the Pb penetration but protected the surface from dissolution. Klíčová slova: corrosion behavior; flowing lead; ods steels; pb; Ferritic-martensitic steel; ods; liquid Pb; oxidation; nuclear application Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. EFFECT OF STEEL COMPOSITION ON ITS BEHAVIOUR IN THE LIQUID LEAD ENVIRONMENT

Ferritic-martensitic Eurofer-97 and oxide dispersion strengthened (ODS) Eurofer steels are potential candidates for structural applications in advanced nuclear reactors. Influence of scandium, ...

Pazderova, M.; Hojná, A.; Vít, J.; Hadraba, Hynek; Čižek, J.
Ústav fyziky materiálů, 2024

QUANTUM-COMPUTING STUDY OF THE ELECTRONIC STRUCTURE OF CRYSTALS: THE CASE STUDY OF SI
Ďuriška, Michal; Miháliková, Ivana; Friák, Martin
2024 - anglický Quantum computing is newly emerging information-processing technology which is foreseen to be exponentially faster than classical supercomputers. Current quantum processors are nevertheless very limited in their availability and performance and many important software tools for them do not exist yet. Therefore, various systems are studied by simulating the run of quantum computers. Building upon our previous experience with quantum computing of small molecular systems (see I. Mihalikova et al., Molecules 27 (2022) 597, and I. Mihalikova et al., Nanomaterials 2022, 12, 243), we have recently focused on computing electronic structure of periodic crystalline materials. Being inspired by the work of Cerasoli et al. (Phys. Chem. Chem. Phys., 2020, 22, 21816), we have used hybrid variational quantum eigensolver (VQE) algorithm, which combined classical and quantum information processing. Employing tight-binding type of crystal description, we present our results for crystalline diamond-structure silicon. In particular, we focus on the states along the lowest occupied band within the electronic structure of Si and compare the results with values obtained by classical means. While we demonstrate an excellence agreement between classical and quantum-computed results in most of our calculations, we further critically check the sensitivity of our results with respect to computational set-up in our quantum-computing study. A few results were obtained also using quantum processors provided by the IBM. Klíčová slova: computation; Quantum computing; crystals; tight-binding method; quantum-mechanical calculations Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. QUANTUM-COMPUTING STUDY OF THE ELECTRONIC STRUCTURE OF CRYSTALS: THE CASE STUDY OF SI

Quantum computing is newly emerging information-processing technology which is foreseen to be exponentially faster than classical supercomputers. Current quantum processors are nevertheless very ...

Ďuriška, Michal; Miháliková, Ivana; Friák, Martin
Ústav fyziky materiálů, 2024

Geologická a geotechnická charakterizace horninového prostředí – PVP Bukov II – třetí průběžná zpráva
Soejono, I.; Bukovská, Z.; Rukavičková, L.; Švagera, O.; Chabr, T.; Souček, Kamil; Vavro, Martin; Morávek, R.; Levý, O.; Sosna, K.; Kryl, J.; Řihošek, J.; Zelinková, T.; Dobeš, P.; Hanák, J.; Čermák, F.; Kašpar, R.; Mareček, L.; Nedvěd, J.; Vavro, Leona; Myška, O.; Janeček, Ivan
2024 - český Tato zpráva popisuje práce zhotovené v třetím roce řešení veřejné zakázky Geologická a geotechnická charakterizace horninového prostředí – PVP Bukov II. Charakterizační a popisné práce přímo navazují na ražbu prostor pro budoucí podzemní laboratoř a zahrnují zejména: geologické a geotechnické dokumentace čeleb a stěn díla, petrografickou, mineralogickou a strukturně geologickou dokumentaci, hydrogeologickou charakterizaci prostředí, dále stanovení fyzikálně-mechanických vlastností horninového masivu in situ a v laboratoři, geofyzikální charakterizaci, monitoring seismických účinků trhacích prací a charakterizaci EDZ. Zpráva také obsahuje nově navržený klasifikační systém horninových bloků a výsledky jeho testování na prostředí PVP Bukov II. Zpráva je doplněna stručným přehledem prací plánovaných pro následující rok řešení projektu. This report describes the work carried out in the third year of the public contract Geological and geotechnical characterisation of the rock environment – the Bukov URF II. The characterisation and descriptive works are directly related to the excavation of the premises for the future underground laboratory. These include in particular: geological and geotechnical documentation of the faces and walls of the workings, petrographic, mineralogical and structural geological documentation, hydrogeological characterisation of the environment, as well as determination of the physical and mechanical properties of the rock-mass in situ and in the laboratory, geophysical characterisation and monitoring of the seismic effects of blasting. The report also includes the newly developed rock mass\nclassification system and the results of its testing on the Bukov URF II site. The report includes also brief overview of the work planned for the following year of the project. Klíčová slova: Bukov URF; geological documentation; 3D model; petrography; geochemistry; petrophysical data; natural radioactivity; physico-mechanical and geotechnical properties; seismic tomography; excavation induced vibration measurement; rock mass classification system Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd. Geologická a geotechnická charakterizace horninového prostředí – PVP Bukov II – třetí průběžná zpráva

Tato zpráva popisuje práce zhotovené v třetím roce řešení veřejné zakázky Geologická a geotechnická charakterizace horninového prostředí – PVP Bukov II. Charakterizační a popisné práce přímo navazují ...

Soejono, I.; Bukovská, Z.; Rukavičková, L.; Švagera, O.; Chabr, T.; Souček, Kamil; Vavro, Martin; Morávek, R.; Levý, O.; Sosna, K.; Kryl, J.; Řihošek, J.; Zelinková, T.; Dobeš, P.; Hanák, J.; Čermák, F.; Kašpar, R.; Mareček, L.; Nedvěd, J.; Vavro, Leona; Myška, O.; Janeček, Ivan
Ústav geoniky, 2024

Stanovení in-situ napjatosti v PVP Bukov II – rešerše metod měření napjatosti a studie jejich využití v procesu výstavby a provozu hlubinného úložiště
Vavro, Martin; Waclawik, Petr; Souček, Kamil; Staš, Lubomír; Koníček, Petr; Jiránková, Eva; Schuchová, Kristýna; Kukutsch, Radovan; Kajzar, Vlastimil
2024 - český Rešerše prezentuje hlavní metody měření a jim odpovídající technickou instrumentaci, které byly v minulosti použity pro stanovení napětí horninového masivu, a to jak v podmínkách PVP Bukov I, respektive dolu Rožná, tak zejména v prostředí vybraných zahraničních podzemních výzkumných laboratoří. Shrnuty jsou rovněž stěžejní výsledky, které byly při těchto měřeních získány. Zjištěné poznatky jsou pak reflektovány v návrhu způsobu měření a monitoringu napětí v různých fázích procesu přípravy a provozu hlubinného úložiště (HÚ) v ČR. Z provedené rešerše stěžejních publikovaných studií a výsledků in situ experimentů vyplývá, že celosvětově nejčastěji používanými způsoby napěťových měření jsou zejména hydraulické štěpení stěn vrtů (hydrofracturing) a metoda odlehčeného vrtného jádra (overcoring). Tyto dvě metody byly rovněž navrženy jako nejvhodnější pro fázi výběru finální lokality HÚ v ČR. Ve fázi budování HÚ bylo doporučeno jejich rozšíření o metodu inverzní analýzy konvergenčních měření. Pro účely měření změn napětí ve stádiu přípravy a provozu HÚ byl jako nejvhodnější doporučen monitoring pomocí tenzometrických CCBM sond. The presented search summarizes main measurement methods and their corresponding technical instrumentation, which were used in the past to determine the stress state of the rock\nmass, both in the conditions of Bukov URF I or the Rožná mine respectively, and especially in the environment of selected foreign underground research laboratories. The key results obtained during these stress measurements are also compiled. The findings are then reflected in the proposed method of rock mass stress measurement and monitoring in various stages of the process of preparing and operating a deep geological repository (DGR) in the Czech Republic. From the conducted search of the crucial published studies and the results of in situ experiments, it follows that the most commonly used methods of stress measurement worldwide are mainly hydraulic fracturing of borehole walls (hydrofracturing) and the overcoring method. These two methods were also proposed as the most suitable for the stage of selecting the final site of the DGR in the Czech Republic. In the phase of construction the DGR, it was recommended to extend them by the method of inverse analysis of convergence measurements. For the purposes of measuring stress changes during the construction and operation of the DGR, monitoring using conical tensometric CCBM probes was recommended as the most suitable. Klíčová slova: high level radioactive waste; geological disposal; deep repository; long-term stability of the repository; Bukov URF; rock mass stress; hydrofracturing; overcoring method; tensometric conical probes; acoustic logging; optical logging; long-term stress monitoring; convergence measurement; numerical modelling Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd. Stanovení in-situ napjatosti v PVP Bukov II – rešerše metod měření napjatosti a studie jejich využití v procesu výstavby a provozu hlubinného úložiště

Rešerše prezentuje hlavní metody měření a jim odpovídající technickou instrumentaci, které byly v minulosti použity pro stanovení napětí horninového masivu, a to jak v podmínkách PVP Bukov I, ...

Vavro, Martin; Waclawik, Petr; Souček, Kamil; Staš, Lubomír; Koníček, Petr; Jiránková, Eva; Schuchová, Kristýna; Kukutsch, Radovan; Kajzar, Vlastimil
Ústav geoniky, 2024

Book of Abstracts. 19th Youth symposium on experimental solid mechanics
Kytýř, Daniel; Zlámal, Petr; Pagliaro, A.; Doktor, T.
2024 - anglický The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all areas of experimental research and its application in solid and fluid mechanics. The topic will particularly concern to: Conventional and advanced experimental methods in solid and fluid mechanics - Non-destructive testing and inspection - Measurements in material science - Computer assisted testing and simulation - Engineering design simulation - Hybrid methods, experimental techniques – Numerical simulation - Optical methods and image processing - Measurements in biomechanics - Sensor techniques for micro- and nano-applications - Measurement methods for forensic engineering Klíčová slova: experimental mechanics; solid mechanics; fluid mechanics Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR. Book of Abstracts. 19th Youth symposium on experimental solid mechanics

The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all ...

Kytýř, Daniel; Zlámal, Petr; Pagliaro, A.; Doktor, T.
Ústav teoretické a aplikované mechaniky, 2024

Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Macháček, Michael; Hračov, Stanislav
2024 - anglický Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, critical onset wind speeds, and global dynamic response of a very low-tensioned line with simulated icing observed on similar real conductors. Due to the highly nonlinear mechanical behavior of such a flexible cable, we employed the Newmark integration method combined with the iterative Newton-Raphson method. We analyzed two numerical models of the overhead line loaded by the wind: one assuming nonlinearity only in the wind load, while retaining the linearity of the mechanical system itself, and the other representing a fully nonlinear system including geometrical nonlinearity. Our analysis revealed that the determined critical wind speeds for the onset of galloping are in relatively close ranges for both models. However, numerical simulations with the fully nonlinear system indicated significantly lower amplitudes of limit cycle oscillations, especially at higher wind speeds, compared to the linear model of the line. This underscores the necessity of using fully nonlinear models during the design stage of such low-tensioned aerial conductors. Klíčová slova: aerial bundled conductors; wind effects; galloping; limit cycle oscillation Plné texty jsou dostupné v digitálním repozitáři Akademie Věd. Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain

Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, ...

Macháček, Michael; Hračov, Stanislav
Ústav teoretické a aplikované mechaniky, 2024

Applicable Adaptive Discounted Fully Probabilistic Design of Decision Strategy
Molnárová, Soňa
2024 - anglický The work addresses the issue of decreased utility of future rewards, referred to as discounting, while utilizing fully probabilistic design (FPD) of decision strategies. FPD obtains the optimal strategy for decision tasks using only probability distributions, which is its main asset. The standard way of solving decision tasks is provided by Markov decision processes (MDP), which FPD covers as a special case. Methods of solving discounted MDPs have already been introduced. However, the use of FPD might be advantageous when solving tasks with an unknown system model. Due to its probabilistic nature, FPD is able to obtain a more precise estimation of this model. After previously introducing discounting and system model estimation to FPD, the current work examines the effect of discounting on decision processes and its possible advantages when dealing with an unknown system model. Klíčová slova: Bayesian estimation; decision making; discounting; forgetting; probabilistic strategy design; supression of aproximate modelling impact Dokument je dostupný na externích webových stránkách. Applicable Adaptive Discounted Fully Probabilistic Design of Decision Strategy

The work addresses the issue of decreased utility of future rewards, referred to as discounting, while utilizing fully probabilistic design (FPD) of decision strategies. FPD obtains the optimal ...

Molnárová, Soňa
Ústav teorie informace a automatizace, 2024