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Paralely a odlišnosti sociálních situací s panickým potenciálem - IMPAKT 2023
Červenka, Jan; Vinopal, Jiří
2024 - Czech
Výzkumná zpráva s hlavními výsledky dotazníkových šetření provedených v rámci projektu „Paralely a odlišnosti sociálních situací s panickým potenciálem - příklad RMU a pandemie koronaviru v české společnosti“ v roce 2023. A research report with main outputs of the surveys conducted under the project „Parallels and Differences of Social Situations with Panic Potential - an example of RMU and a coronavir pandemic in Czech society“ in 2023.
Keywords:
social panic; radiation; citizen science
Available at various institutes of the ASCR
Paralely a odlišnosti sociálních situací s panickým potenciálem - IMPAKT 2023
Výzkumná zpráva s hlavními výsledky dotazníkových šetření provedených v rámci projektu „Paralely a odlišnosti sociálních situací s panickým potenciálem - příklad RMU a pandemie koronaviru v české ...
Vrt DO 599. Paleomagnetický a magnetomineralogický výzkum. Závěrečná zpráva
Kdýr, Šimon; Pruner, Petr; Uçar, Hakan; Elbra, Tiiu
2024 - Czech
Keywords:
palaeomagnetism; rock-magnetism; greigite
Available at various institutes of the ASCR
Vrt DO 599. Paleomagnetický a magnetomineralogický výzkum. Závěrečná zpráva
Využití termografie v průzkumech památek
Valach, Jaroslav; Eisler, Marek
2024 - Czech
Termografie rozšiřuje portfolia metod, jimiž lze studovat vlastnosti objektů okolního světa. Ještě před deseti lety byla tato technologie kvůli potenciálním vojenským aplikacím úzkostlivě kontrolována, což omezovalo konkurenci v nabídce výrobků a výrobců a vedlo k vysokým cenám zařízení založených na těchto principech. Teprve díky uvolnění této kontroly došlo k rozmachu výroby a zpřístupnění zjednodušených výrobků masovému využití, takže si dnes může zákazník například pořídit chytrý telefon s doplňkovým termografickým modulem jen s malým navýšením ceny. Spolu s dostupností zařízení pozorujeme nárůst uplatnění termografie v mnoha oblastech, včetně průzkumů staveb a památek. Thermography expands the portfolio of methods that can be used to study the properties of objects in the surrounding world. As recently as a decade ago, the technology was frowned upon for potential military applications controlled, which limited competition in the offer of products and manufacturers and led to high prices of devices based on these principles. It was only thanks to the release of this control that it happened to expand production and make simplified products available to mass use, so get it today for example, a customer can purchase a smartphone with an additional thermographic module for only with a small price increase. Together with the availability of equipment, we observe an increase in the application of thermography in many areas, including surveys of buildings and monuments.
Keywords:
thermography; survey of historical structures
Available at various institutes of the ASCR
Využití termografie v průzkumech památek
Termografie rozšiřuje portfolia metod, jimiž lze studovat vlastnosti objektů okolního světa. Ještě před deseti lety byla tato technologie kvůli potenciálním vojenským aplikacím úzkostlivě ...
Microstructure modifications of Al-Si-coated press-hardened steel 22MnB5 by laser welding
Šebestová, Hana; Horník, Petr; Mika, Filip; Mikmeková, Šárka; Ambrož, Ondřej; Mrňa, Libor
2024 - English
Weld microstructure depends on the characteristics of welded materials and parameters of welding technology, especially on the heat input that determines the peak temperature and the cooling rate. When the coated sheets are welded, the effect of the chemical composition of the coating must be also considered even though its thickness is only a few tens of microns. During 22MnB5+AlSi laser welding experiments, the ferrite-stabilizing elements of coating modified the weld metal microstructure. Ferrite appeared in a quenched weld metal. The rapid cooling rate accompanying welding with a focused beam limited the homogenization of the weld metal which resulted in the formation of ferritic bands in the regions rich in Si and especially in Al. On the other hand, a high level of homogenization was reached when welding with the defocused beam. The ferritic islands uniformly distributed in the weld metal were formed at 0.4 wt% and 1.6 wt% of Si and Al, respectively. The doubled heat input reduced the Al content to 0.7 wt% insufficient for the ferrite formation at still relatively high cooling rates. Predicting the distribution of ferrite in the weld metal is challenging due to its dependence on various factors, such as cooling rate and the volume of dissolved coating, which may vary with any modifications made to the welding parameters.
Keywords:
laser welding; high-strength steel; microstructure; heat input; ferrite stabilization
Available at various institutes of the ASCR
Microstructure modifications of Al-Si-coated press-hardened steel 22MnB5 by laser welding
Weld microstructure depends on the characteristics of welded materials and parameters of welding technology, especially on the heat input that determines the peak temperature and the cooling rate. ...
Influence of ball material on the resulting fatigue life of thermal sprayed HVOF coatings in dynamic impact testing
Duliškovič, J.; Daniel, Josef; Houdková, Š.
2024 - English
Dynamic impact wear, i.e. contact between two components in the presence of high cyclic local loads, is a challenging failure mode that occurs in many mechanical applications. Many previous studies have confirmed that dynamic impact testing is suitable for evaluating the contact fatigue of thermal sprayed coatings. However, the effect of the test parameters on the resulting lifetime is unclear. The aim of this study describes the effect of the ball material used in the dynamic impact test on the resulting fatigue life of the HVOF thermal sprayed coating. Three test balls made of WC/Co alloy, Si3N4 silicon nitride and 440 C steel were chosen for this study. Dynamic impaction testing was carried out on the Cr3C2-NiCr coating, which was sprayed by HVOF on a 1.2376 high-speed steel substrate. The impact lifetime was described by the number of critical impacts, i.e. the number of impacts before coating fatigue occurs. Furthermore, the depth and volume of impact craters were measured. Using scanning electron microscopy (SEM), the surface of the impacts as well as the microstructure of the coating on the cross-section in the region of the impacts were observed. Furthermore, the mechanism of crack propagation in the coating and the microstructure of the indentor were investigated.
Keywords:
dynamic impact test; HVOF; Cr3C2-NiCr; fatigue
Available at various institutes of the ASCR
Influence of ball material on the resulting fatigue life of thermal sprayed HVOF coatings in dynamic impact testing
Dynamic impact wear, i.e. contact between two components in the presence of high cyclic local loads, is a challenging failure mode that occurs in many mechanical applications. Many previous studies ...
Surfactant-free silver nanofluids as liquid systems with neuromorphic potential
Nikitin, D.; Biliak, K.; Lemke, J.; Protsak, M.; Pleskunov, P.; Tosca, M.; Ali-Ogly, S.; Červenková, V.; Adejube, B.; Bajtošová, L.; Černochová, Zulfiya; Prokeš, J.; Křivka, I.; Biederman, H.; Faupel, F.; Vahl, A.; Choukourov, A.
2024 - English
Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based on the resistive switching effect, which involves changing the device’s conductivity in response to an external electric field. For instance, percolating nanoparticle (NP) networks produced by gas aggregation cluster sources (GAS) show collective spiking behavior in conductivity reminiscent of brain-like dynamics. Nevertheless, the problem of dynamic spatial reconfiguration in solid-state neuromorphic systems remains unsolved. Herein, novel nanofluids with resistive switching properties are proposed as neuromorphic media. They are produced by depositing silver NPs from GAS into vacuum-compatible liquids (paraffin, silicon oil, and PEG) without the use of surfactants or other chemicals. When the electric field is applied between two electrodes, the migration of NPs toward biased electrode is detected in all liquids. The electrophoretic nature of the NP movement was proved by means of ζ-potential measurements. Such movement led to the self-assembly of NPs in conductive paths connecting the electrodes and, as a result, to resistive switching. The electrical response was strongly dependent on the dielectric constant of the base liquid. The Ag-PEG nanofluid demonstrated the best switching performance reproducible during several tens of current-voltage cycles. The growth of flexible and reconfigurable conductive filaments in nanofluids makes them suitable media for potential realization of 3D neural networks.
Keywords:
nanofluid; gas aggregation cluster source; ζ-potential, electrophoresis
Available at various institutes of the ASCR
Surfactant-free silver nanofluids as liquid systems with neuromorphic potential
Neuromorphic engineering is a rapidly developing branch of science that aims to implement the unique attributes of biological neural networks in artificial devices. Most neuromorphic devices are based ...
QUANTUM-MECHANICAL STUDY OF INTERNAL STRUCTURAL TRANSFORMATIONS IN Pb-SUPERSATURATED Pb-Sn ALLOYS
Friák, Martin; Čípek, Petr; Pavlů, J.; Roupcová, Pavla; Miháliková, Ivana; Msallamová, Š.; Michalcová, A.
2024 - English
Motivated by a decades-long controversy related to the crystal structure of Pb-supersaturated solid solutions of Pb in Sn, we have performed a quantum-mechanical study of these materials. Focusing on both body-centred-tetragonal beta-Sn and simple-hexagonal gamma-Sn structures, we have computed properties of two alloys with the chemical composition Pb5Sn11, i.e. 31.25 at. % Pb, which is close to the composition of the experimentally found alloy (30 at. % Pb). The 16-atom computational supercells were designed as multiples of the elemental beta- and gamma-Sn unit cells, where the Pb atoms were distributed according to the special quasi-random structure (SQS) concept. Full structural relaxations of both beta- and gamma-phase-based alloys resulted in very significant re-arrangements into structures which do not exhibit any apparent structural features typical for the original alloys, and are, therefore, difficult to classify. The formation energies of the beta- and gamma-phase-originating equilibrium phases are 50 meV/atom and 53 meV/atom, respectively. Therefore, they are not stable with respect to the decomposition into the elemental lead and tin. Moreover, our calculations of elastic constants of both phases revealed that they are close to mechanical instability. Our results indicate that the studied Pb-supersaturated Pb-Sn solid solutions may be prone to structural instability, transformations into different phases and decomposition. Our findings may contribute into the identification of the reason why the subsequent experimental studies did not reproduce the initial published data.
Keywords:
tin; crystal; Pb-Sn alloys; stability; supersaturation; quantum-mechanical calculations
Available at various institutes of the ASCR
QUANTUM-MECHANICAL STUDY OF INTERNAL STRUCTURAL TRANSFORMATIONS IN Pb-SUPERSATURATED Pb-Sn ALLOYS
Motivated by a decades-long controversy related to the crystal structure of Pb-supersaturated solid solutions of Pb in Sn, we have performed a quantum-mechanical study of these materials. Focusing on ...
IPC-IOPC 2024: Abstract book
Bek, Jiří; Votočková Frojdová, Jana
2024 - English
Keywords:
Palaeobotany; palynology; plants; spores
Available at various institutes of the ASCR
IPC-IOPC 2024: Abstract book
Functional Tungsten-based thin films and their characterization
Košelová, Zuzana; Horáková, L.; Sobola, Dinara; Burda, Daniel; Knápek, Alexandr; Fohlerová, Z.
2024 - English
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.
Keywords:
cold-field emission; thin layer deposition; tungsten oxide; resonance enhanced tunneling; anodization
Available at various institutes of the ASCR
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 ...
Brno lingvistické
Vykypěl, Bohumil
2024 - Czech
Keywords:
Moravia; personality; linguistics
Available at various institutes of the ASCR
Brno lingvistické
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