Number of found documents: 1107
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Mikroskopický laboratorní rozbor vzorku sgrafita z domu ve Venhudově ulici v Brně
Slížková, Zuzana; Kozlovcev, Petr; Koudelková, Veronika; Novák, Vladimír
2017 - Czech
Zpráva obsahuje výsledky mikroskopického rozboru vzorku sgrafita z 50.let 20. stol. na fasádě domu ve Venhudově ulici v Brně. Byla analyzována bílá povrchová vrstva a podkladní červenohnědá vrstva malty pomocí optické mikroskopie a elektronové mikroskopie ve spojení s prvkovou analýzou SEM-EDS. Report presents results of microscopic characterization of sgraffito from the the fifties of the twentieth century sampled from house façade in Brno, Venhudova street, CR. Light (optical) microscopy and electron microscopy SEM-EDS were used for characterization of the aggregate and the binder of two layers of sgraffito. Keywords: sgraffito, analysis; plaster; render; SEM-EDS; microscopy Available at various institutes of the ASCR
Mikroskopický laboratorní rozbor vzorku sgrafita z domu ve Venhudově ulici v Brně

Zpráva obsahuje výsledky mikroskopického rozboru vzorku sgrafita z 50.let 20. stol. na fasádě domu ve Venhudově ulici v Brně. Byla analyzována bílá povrchová vrstva a podkladní červenohnědá vrstva ...

Slížková, Zuzana; Kozlovcev, Petr; Koudelková, Veronika; Novák, Vladimír
Ústav teoretické a aplikované mechaniky, 2017

Výzkumná zpráva. Dýka v pochvě – Praha západ
Kumpová, Ivana
2017 - Czech
Byla provedena tomografie bronzové dýky z čerstvého archeologického nálezu a vytvořeny vizualizace. Výzkum byl proveden na zařízení TORATOM v Centru excelence Telč. Tomography of a bronze dagger from a recent archaeological finding was performed and visualizations were created. The research was done using the TORATOM device in the Centre of Excellence Telč. Keywords: bronze dagger; TORATOM; archaeology Available at various institutes of the ASCR
Výzkumná zpráva. Dýka v pochvě – Praha západ

Byla provedena tomografie bronzové dýky z čerstvého archeologického nálezu a vytvořeny vizualizace. Výzkum byl proveden na zařízení TORATOM v Centru excelence Telč....

Kumpová, Ivana
Ústav teoretické a aplikované mechaniky, 2017

Research report 2013-11-08 Calcite_S12
Kumpová, Ivana; Vopálenský, Michal; Vavřík, Daniel
2017 - English
Porosity was measured on a irregular sample of calcite, designated Calcite_S12, using the TORATOM device in the Centre of Excellence Telč. Keywords: calcite; TORATOM; measuring Available at various institutes of the ASCR
Research report 2013-11-08 Calcite_S12

Porosity was measured on a irregular sample of calcite, designated Calcite_S12, using the TORATOM device in the Centre of Excellence Telč.

Kumpová, Ivana; Vopálenský, Michal; Vavřík, Daniel
Ústav teoretické a aplikované mechaniky, 2017

Beton s ocelovou výztuží
Kumpová, Ivana; Jandejsek, Ivan; Vavřík, Daniel
2017 - Czech
Práce byla zaměřena na RTG tomografii a vytvoření 3D počítačových modelů deseti vzorků betonu s různým obsahem ocelové výztuže a různou technologií výroby. Z těchto modelů byly dále vypočteny objemové poměry jednotlivých složek (beton:výztuž:póry) a směrové rozložení jednotlivých vláken. The work was focused on X-Ray tomography and creating of 3D computer models of ten concrete samples with various steel reinforcement contents and different production technology. From these models, the volume ratios of individual components (concrete: reinforcement: pores) and directional layout of individual fibers were calculated. Keywords: X-Ray tomography; 3D computer model; reinforced concrete Available at various institutes of the ASCR
Beton s ocelovou výztuží

Práce byla zaměřena na RTG tomografii a vytvoření 3D počítačových modelů deseti vzorků betonu s různým obsahem ocelové výztuže a různou technologií výroby. Z těchto modelů byly dále vypočteny objemové ...

Kumpová, Ivana; Jandejsek, Ivan; Vavřík, Daniel
Ústav teoretické a aplikované mechaniky, 2017

Stochastic stability of the generalized van der Pol system under random additive excitation
Náprstek, Jiří; Fischer, Cyril
2017 - English
The paper is motivated by a series of wind tunnel experiments investigating aeroelastic SDOF and TDOF section models of various shape and aeroelastic properties. It reveals that most of them can be theoretically modeled by the van der Pol – Duffing type equations or their combination adjusting degree of individual nonlinear terms or their coefficients. It should be emphasized that this character of the system response is very stable and is obvious in linear as well as in weakly nonlinear domain when the post-critical effect emerges. Moreover, many special effects identified by an experimental way evoke properties recognized in the pure theory of differential equations. Keywords: wind tunnel experiment; random excitation; stochastic stability Available at various institutes of the ASCR
Stochastic stability of the generalized van der Pol system under random additive excitation

The paper is motivated by a series of wind tunnel experiments investigating aeroelastic SDOF and TDOF section models of various shape and aeroelastic properties. It reveals that most of them can be ...

Náprstek, Jiří; Fischer, Cyril
Ústav teoretické a aplikované mechaniky, 2017

Formace polymorfů uhličitanu vápenatého během mísení koncentrovaných roztoků solí
Ševčík, Radek; Mácová, Petra; Viani, Alberto
2017 - Czech
Příspěvek se zaobírá předběžnými výsledky studia gelové fáze vznikající během mísení koncentrovaných roztoků solí během syntézy polymorfů uhličitanu vápenatého. Během reakce bylo odebráno několik vzorků, které byly následně zkoumány instrumentálními technikami jako např. skenovací elektronový mikroskop. This contribution is demonstrated the preliminary results of the study of the gel phase forming during the synthesis of calcium carbonate's polymorphs. Several samples were collected during the reaction and they were subsequently investigated with instrumental techniques e.g. scanning electron microscopy. Keywords: CaCO3; polymorphs; synthesis; vaterite; ACC Available at various institutes of the ASCR
Formace polymorfů uhličitanu vápenatého během mísení koncentrovaných roztoků solí

Příspěvek se zaobírá předběžnými výsledky studia gelové fáze vznikající během mísení koncentrovaných roztoků solí během syntézy polymorfů uhličitanu vápenatého. Během reakce bylo odebráno několik ...

Ševčík, Radek; Mácová, Petra; Viani, Alberto
Ústav teoretické a aplikované mechaniky, 2017

Optimization of acquisition parameters in radiography and tomography
Vopálenský, Michal; Vavřík, Daniel; Kumpová, Ivana
2017 - English
Contrast in radiographic images is one of the most important parameters both in radiography and tomography. This paper investigates the possibility of adjusting the radiographic parameters, in particular the accelerating voltage of the X-ray tube, in order to maximize the difference in the detected intensity in response to the change in the thickness of the investigated object. Simplified model is used that allows finding the optimal operating point for the given material and thickness without an apriory knowledge about the X-ray spectra, detector response and the material composition. It is shown that in case of small changes of thickness, the optimum is met when the detected intensity behind the object of certain thickness is at approx. 37 % of the full range (i.e., of the value that would be measured under the same conditions in the absence of the object). In spite of simplifications made, the theoretical model shows a very good correspondence with the experimental data. A brief consideration is made on the case of a general difference in thicknesses. Keywords: X-ray computed tomography; X-ray radiography; X-ray optimization; image processing; contrast Fulltext is available at external website.
Optimization of acquisition parameters in radiography and tomography

Contrast in radiographic images is one of the most important parameters both in radiography and tomography. This paper investigates the possibility of adjusting the radiographic parameters, in ...

Vopálenský, Michal; Vavřík, Daniel; Kumpová, Ivana
Ústav teoretické a aplikované mechaniky, 2017

Early stage microstructure development of cement paste modified by crystalline admixture
Hrbek, V.; Petráňová, Veronika; Němeček, J.
2017 - English
This paper deals with the effect of crystalline admixture (CA) on the microstructure of the cementitious composite in first four weeks after the production. Previous investigation was performed on reference specimens consisting of pure cement. Samples of pure CA and cement modified by 1% of CA with the same w/c ratio were examined and compared in this paper. By investigation of these materials on the micro-scale, it is possible to identify the development of the microstructure of each and determine the impact of the modification. For this purpose, backscattered electrons microscopy (BSE) with energy-dispersive X-ray spectroscopy (EDX) was used for phase analysis as well as instrumental nano-indentation to obtain micro-mechanical properties. Presented results show the evolution of mechanical properties and microstructure in time and the impact of the crystalline admixture on modified cement. Keywords: cement; crystalline admixture; microstructure; nanoindentation; phase; SEM Available at various institutes of the ASCR
Early stage microstructure development of cement paste modified by crystalline admixture

This paper deals with the effect of crystalline admixture (CA) on the microstructure of the cementitious composite in first four weeks after the production. Previous investigation was performed on ...

Hrbek, V.; Petráňová, Veronika; Němeček, J.
Ústav teoretické a aplikované mechaniky, 2017

Investigation of Strouhal number of ice-accreted bridge cables at moderate flow turbulence
Górski, P.; Tatara, M.; Pospíšil, Stanislav; Kuznetsov, Sergeii
2017 - English
This paper is concerned with the investigation of the Strouhal number (St) for a stationary iced cable model of cable-supported bridges using wind tunnel tests with respect to three principal angles of wind attack. The investigations were carried out in the Climatic Wind Tunnel Laboratory of the Czech Academy of Sciences in Telč. The St values were determined at the flow turbulence intensity of the order of 12%, within the range of the Reynolds number from 2.4·10^4 to 12.9·10^4, based on the dominant vortex shedding frequencies measured in the wake of the model. The obtained experimental St values of the iced cable of a cable-supported bridge will allow to determine the critical wind velocity as well as will be helpful for prediction of the cable response due to the vortex excitation phenomenon at moderate flow turbulence condition. Keywords: Strouhal number; climatic wind tunnel; vortex excitation phenomenon; cable-supported bridge Available at various institutes of the ASCR
Investigation of Strouhal number of ice-accreted bridge cables at moderate flow turbulence

This paper is concerned with the investigation of the Strouhal number (St) for a stationary iced cable model of cable-supported bridges using wind tunnel tests with respect to three principal angles ...

Górski, P.; Tatara, M.; Pospíšil, Stanislav; Kuznetsov, Sergeii
Ústav teoretické a aplikované mechaniky, 2017

Measurements of dynamic wind pressures on gable roofs – comparison with ČSN EN 1991-1-4
Pospíšil, Stanislav; Macháček, Michael; Hračov, Stanislav; Kuznetsov, Sergeii; Trush, Arsenii
2017 - English
The contribution is dealing with the wind tunnel measurements of dynamic pressures on the canopy roofs. It compares experimentally determined pressure coefficients Cp with the values in ČSN EN 1991-1-4 and former code ČSN 73 0035 as well. The pressures are expressed by the dynamic values. Thus, the averaged values are presented together with the fluctuating part, which significantly contributes to the overall loading. The measurement is carried out at two roof models, two basic directions, and two turbulence intensities. Keywords: wind tunnel experiments; dynamic pressures on roofs; wind loads; wind load codes; gable roof; atmospheric boundary layer Available at various institutes of the ASCR
Measurements of dynamic wind pressures on gable roofs – comparison with ČSN EN 1991-1-4

The contribution is dealing with the wind tunnel measurements of dynamic pressures on the canopy roofs. It compares experimentally determined pressure coefficients Cp with the values in ČSN EN ...

Pospíšil, Stanislav; Macháček, Michael; Hračov, Stanislav; Kuznetsov, Sergeii; Trush, Arsenii
Ústav teoretické a aplikované mechaniky, 2017

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