Výsledky mikroskopické analýzy vzorků malt odebraných z objektů: věž kláštera v Sázavě, Apolinář v Praze
Bauerová, Pavla; Frankeová, Dita; Vondráčková, Michaela
2023 - český
omocí elektronového mikroskopu a EDS analýzy byly zkoumány vzorky ze dvou lokalit - vzorek malty z věže kláštera v Sázavě a dva vzorky omítky z objektu Apolinář v Praze (Apolinář – líc, Apolinář – půda). Cílem zkoumání bylo zejména určit druh pojiva omítek a nátěrů na omítce. Ve všech třech analyzovaných vzorcích bylo identifikováno silně hydraulické pojivo. Using an electron microscope and EDS analysis, samples from two locations were examined - a sample of mortar from the tower of the monastery in Sázava and two samples of plaster from the Apolinař building in Prague (Apolinář - face, Apolinář - soil). The aim of the investigation was to determine the type of binder for plasters and coatings on plaster. A strongly hydraulic binder was identified in all three analyzed samples.
Klíčová slova:
microscopy; EDS analysis; mortars
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Výsledky mikroskopické analýzy vzorků malt odebraných z objektů: věž kláštera v Sázavě, Apolinář v Praze
omocí elektronového mikroskopu a EDS analýzy byly zkoumány vzorky ze dvou lokalit - vzorek malty z věže kláštera v Sázavě a dva vzorky omítky z objektu Apolinář v Praze (Apolinář – líc, Apolinář – ...
Conductive open-cell silicone foam for modulatable damping and impact sensing applications
Preuer, R.; Šleichrt, Jan; Kytýř, Daniel; Graz, I.
2023 - anglický
Nature has long served as a source of inspiration for the development of new materials, with foam-like structures in fruits such as oranges and pamelos serving as examples of efficient energy dissipation. In this study, we present the synthesis and characterization of a conductive silicone foam for potential impact sensing applications. By blending Sylgard 184 and Carbon Black, we create a highly porous structure capable of dissipating energy and modulating its resistance. To investigate the properties of the foam, we utilized both micro-computer tomography (μCT) and scanning electron microscopy (SEM) imaging techniques. The μCT imaging revealed the intricate pore network of the foam, reminiscent of the complex structure found in natural sponges. SEM imaging allowed for observation of the uniform distribution of Carbon Black particles within the foam, enabling the conductive properties of the foam. The foam’s mechanical behavior was characterized by a compression test under μCT imaging to measure the deformation behavior and changes in the foam’s resistance. Additionally, a ball drop test was conducted to investigate the foam’s damping behavior while simultaneously measuring the impact location by the local change in resistance. Remarkably, our results demonstrate the exceptional damping capabilities of the conductive silicone foam, with the damping ratio modulated by adjusting the degree of compression-induced deformation. This is attributed to the collapse of the foam’s porous structure, resulting in a significant increase in the foam’s contact area. Overall, our study provides valuable insights into the behavior of conductive silicone foams and their potential as an impact sensing material. The use of both CT and SEM imaging techniques allows for a comprehensive understanding of the foam’s properties, which can be optimized for a variety of applications. The foam’s ability to modulate its damping properties by adjusting the degree of deformation provides a promising avenue for future research in the field of materials science and engineering.
Klíčová slova:
silicone foam; conductive properties; deformation behaviour; damping
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Conductive open-cell silicone foam for modulatable damping and impact sensing applications
Nature has long served as a source of inspiration for the development of new materials, with foam-like structures in fruits such as oranges and pamelos serving as examples of efficient energy ...
Characterization of five mosaic mortar beds from Austria produced by A. Neuhauser/Tiroler Glasmalerei and J. Pfefferle
Bauerová, Pavla; Frankeová, Dita; Slížková, Zuzana
2023 - anglický
The report contains the results of material analyses of five mortar beds of mosaics produced by the Austrian studios Neuhauser/Tiroler Glasmalerei and Josef Pfefferle. The analysed samples come from mosaics made at the turn of the 19th and 20th centuries and located in various places in Tyrol. The mortars were analysed by SEM-EDS and thermal analysis. The results showed that, in addition to traditional materials such as marble dust, they also contain atypical or innovative components such as waste ceramic and glass shards or early Portland cement.
Klíčová slova:
SEM-EDS analysis; historic mortar; mosaic; thermal analysis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Characterization of five mosaic mortar beds from Austria produced by A. Neuhauser/Tiroler Glasmalerei and J. Pfefferle
The report contains the results of material analyses of five mortar beds of mosaics produced by the Austrian studios Neuhauser/Tiroler Glasmalerei and Josef Pfefferle. The analysed samples come from ...
Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens
Glinz, J.; Maurer, J.; Holzleitner, M.; Pace, F.; Stamopoulos, A.; Vopálenský, Michal; Kumpová, Ivana; Eckl, M.; Kastner, J.; Senck, S.
2023 - anglický
The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific application’s needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. In a recent study [1], additively manufactured (AM) continuous fiber reinforced tensile test specimens have been investigated regarding the effect of amount and material of the embedded continuous fibers on tensile strength and AM build quality. During these tensile tests, a sudden reduction in tensile stress, which most likely was not related to actual rupture of continuous fibers, was noticeable. Since X-ray computed tomography (XCT) scans were performed only prior to and after the tensile testing, a detailed investigation on the origin of these drops in tensile stress was not possible. Within this work, we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress.
Klíčová slova:
additive manufacturing; composites; X-ray computed tomography; in-situ tensile testing
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens
The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific application’s needs. However, ...
Vyšetření základních mechanických a lomově-mechanických vlastností vzorků odebraných z VTL plynovodu – lokalita L177/2 po čtrnáctiměsíční expozici ve vlhkém vodíku při tlaku 3 MPa
Gajdoš, Lubomír; Šperl, Martin; Šorm, Filip; Bejdl, Jan
2022 - český
Vyšetření vlivu vlhkého vodíku stlačeného na tlak 3 MPa na mechanické a lomové vlastnosti plynovodní oceli ČSN 13126, tahové vzorky, Charpy vzorky i CT vzorky byly během expozice ve vlhkém vodíku trvale zatíženy, po čtrnácti měsících expozice byl zjištěn pokles tažnosti tahových vzorků, pokles lomových parametrů Jin a J0,2 a mírné zvýšení parametru Jm. Investigation of the effect of moist hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a fourteen months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased.\n
Klíčová slova:
stress-strain diagram; Ramberg-Osgood dependence; impact strength; fracture toughness
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Vyšetření základních mechanických a lomově-mechanických vlastností vzorků odebraných z VTL plynovodu – lokalita L177/2 po čtrnáctiměsíční expozici ve vlhkém vodíku při tlaku 3 MPa
Vyšetření vlivu vlhkého vodíku stlačeného na tlak 3 MPa na mechanické a lomové vlastnosti plynovodní oceli ČSN 13126, tahové vzorky, Charpy vzorky i CT vzorky byly během expozice ve vlhkém vodíku ...
Příspěvek ke zkoumání nejstarších dějin zámku v Telči
Drdácký, Miloš; Buzek, Jaroslav
2022 - český
Souhrnná výzkumná zpráva předkládá výsledky výzkumu nejstarších stavebních reliktů telčského zámku. Využívá radiouhlíkového datování kosterních pozůstatků, nedestruktivního průzkumu termovizí a georadarem a 3D fotogrammetrických rekonstrukcí tvaru a rozměrů architektonických prvků. Analyzuje i templářské stopy na Telčsku a v širším regionu. The summary research report presents the results of research into the oldest building relics of Telč Castle. It uses radiocarbon dating of skeletal remains, non-destructive surveying by thermal imaging and ground-penetrating radar, and 3D photogrammetric reconstructions of the shape and dimensions of architectural elements. It also analyzes Templar traces in Telč region and in the wider region.
Klíčová slova:
historic architecture; Templars; archaeological survey; ground penetrating radar (GPR); age analysis of bones; 3D documentation
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Příspěvek ke zkoumání nejstarších dějin zámku v Telči
Souhrnná výzkumná zpráva předkládá výsledky výzkumu nejstarších stavebních reliktů telčského zámku. Využívá radiouhlíkového datování kosterních pozůstatků, nedestruktivního průzkumu termovizí a ...
Innovative device for the simulation of environmental conditions and testing of building materials
Cacciotti, Riccardo; Wolf, Benjamin; Macháček, Michael; Frankl, Jiří
2022 - anglický
Excessive humidity influences the performance of building envelopes and the safety of their occupants. Moisture related problems can indeed impose significant health risks for buildings’ users and even lead, under extreme scenarios, to structural failures. This paper investigates an innovative experimental setup for evaluating the influence of changing environmental conditions on the performance of building materials. It stems out from a broader ongoing research aimed at studying the trends of mould growth on wooden building components. The presented results include the design, construction and numerical validation of a small-scale climatic wind tunnel (2m x 1.8m ca.) to be used for the simulation of natural ventilation and daily humidity and temperature fluctuations. Key findings include the final design of a low cost, modular construction which allows gathering reliable data on the response of building materials exposed to changing boundary conditions, intended for improving current mould growth models. Future work is also suggested.
Klíčová slova:
building envelope; moisture; building material; wind tunnel; performance
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Innovative device for the simulation of environmental conditions and testing of building materials
Excessive humidity influences the performance of building envelopes and the safety of their occupants. Moisture related problems can indeed impose significant health risks for buildings’ users and ...
Application of first integrals in the construction of the Lyapunov function for the random response stability testing
Náprstek, Jiří; Fischer, Cyril
2022 - anglický
The paper deals with a possibility of using the properties of first integrals for the construction of Lyapunov function for the analysis of a dynamic system stability in the stochastic domain. It points out certain characteristics of first integrals resulting in the necessity to introduce additional constraints to assure the principal properties of the Lyapunov function. A number of these constraints has their physical interpretation with reference to system stability. The advantage of this method constructing the Lyapunov function consists in the fact that the Lyapunov function itself contains information on the examined system and, consequently, it is not merely a positive definite function without any relation to the actual case concerned. The presented theory finds application in many dynamical systems. The procedure is illustrated by a nonlinear SDOF example.
Klíčová slova:
stochastic stability; Lyapunov function; first integrals; cyclic coordinates
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Application of first integrals in the construction of the Lyapunov function for the random response stability testing
The paper deals with a possibility of using the properties of first integrals for the construction of Lyapunov function for the analysis of a dynamic system stability in the stochastic domain. It ...
Conservation standards for archaeological sites
Drdácký, Miloš; Drdácký, Tomáš; Novotný, Jakub; Přechová, Barbora
2022 - anglický
The report provides a set of principles for the preventive protection, conservation and management of archaeological sites exposed to the threats of global hazards, especially natural disasters and long-term weather effects.\n\n
Klíčová slova:
conservation; archaeological sites; Danube limes monument; natural hazards; preventive measures
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Conservation standards for archaeological sites
The report provides a set of principles for the preventive protection, conservation and management of archaeological sites exposed to the threats of global hazards, especially natural disasters and ...
Determination of aerodynamic coefficients for air flow around U-profiles with different flange porosities
Ledvinková, Blanka; Hračov, Stanislav; Macháček, Michael
2022 - anglický
Our contribution presents the comparison of the experimental investigations and of the numerical 2D simulations of the air flow around U –profiles having different flange porosities. The U-shaped beams were exposed to the air flow having a given velocity at different angles of the wind attack for obtaining the curves of the aerodynamic coefficients depending on the impact angle. The numerical simulations of the wind tunnel testing were performed using the Unsteady Reynolds Averaged Navier-Stokes (RANS) method, k-ω SST turbulence model was assumed.
Klíčová slova:
U-shaped beams; porosity; wind tunnel; RANS simulation; k-ω SST model
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Determination of aerodynamic coefficients for air flow around U-profiles with different flange porosities
Our contribution presents the comparison of the experimental investigations and of the numerical 2D simulations of the air flow around U –profiles having different flange porosities. The U-shaped ...
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