Number of found documents: 1112
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Probability density determination by means of Gibbs entropy probability density
Náprstek, Jiří; Fischer, Cyril
2019 - English
A method of random response investigation of a nonlinear dynam-ical system is discussed. In particular, the solution of the probability density of a single/multi-degree of freedom (SDOF/MDOF) system response is investigated. Multiple stable equilibrium states with possible jumps of the snap-through type among them are considered. The system is Hamiltonian with weak damping excited by a set of non-stationary Gaussian white noises. The solution, which is based on the Gibbs principle of the maximum entropy of probability, can be employed in various branches of engineering. The search for the extreme of the Gibbs entropy functional is formulated as a constrained optimization problem. The secondary constraints follow from the Fokker-Planck equation (FPE) for the system considered or from the system of ordinary di_erential equations for the stochastic moments of the response derived from the relevant FPE Keywords: Fokker-Planck equation; Gibbs entropy functional; maximum entropy; probability density principle Available at various institutes of the ASCR
Probability density determination by means of Gibbs entropy probability density

A method of random response investigation of a nonlinear dynam-ical system is discussed. In particular, the solution of the probability density of a single/multi-degree of freedom (SDOF/MDOF) system ...

Náprstek, Jiří; Fischer, Cyril
Ústav teoretické a aplikované mechaniky, 2019

Large-area scans of paintings with high resolution
Vopálenský, Michal; Kumpová, Ivana
2019 - Czech
The aim of the measurement was to obtain the radiographs from historical paintings from the Faculty of Restoration of the University Pardubice. Due to the dimensions of the paintings (up to 90 x 110 cm) it was necessary to develop a suitable measurement procedure for successive scanning of the paintings in the TORATOM device. The resulting data are important for the planning of the restoration processes of the paintings and can help to discover otherwise invisible details, like underpaintings etc. Cílem měření bylo získat radiografická data z historických maleb, zapůjčených Fakultou restaurování Univerzity Pardubice. Vzhledem k rozměru obrazů (až 90 × 110 cm) bylo třeba vytvořit vhodnou měřicí proceduru pro postupné skenování pláten v zařízení TORATOM. Výsledná data mají význam pro plánování restaurátorských prací na obrazech a mohou pomoci odhalit jinak neviditelné detaily v malbách, např. podmalby apod. Keywords: large-area X-ray scanning; radiography of fine-art objects; restoration of paintings Available at various institutes of the ASCR
Large-area scans of paintings with high resolution

The aim of the measurement was to obtain the radiographs from historical paintings from the Faculty of Restoration of the University Pardubice. Due to the dimensions of the paintings (up to 90 x 110 ...

Vopálenský, Michal; Kumpová, Ivana
Ústav teoretické a aplikované mechaniky, 2019

Reconstruction of the Renaissance sand-coloured sgraffito based on the material copy
Válek, Jan; Skružná, Olga; Kozlovcev, Petr; Waisserová, J.; Wichterlová, Z.; Jiroušek, Josef
2019 - Czech
The aim of the method is to provide a methodical design for the preparation of sand made sgraffito mortar and show its use on a specific example. Cílem památkového postupu je poskytnout metodický návrh přípravy maltového doplňku pískového\nsgrafita a ukázat jeho využití na konkrétním příkladu. Keywords: renaissance sgraffito; repairs of plasters; traditional building technologies; traditional lime techniques Available in a digital repository NRGL
Reconstruction of the Renaissance sand-coloured sgraffito based on the material copy

The aim of the method is to provide a methodical design for the preparation of sand made sgraffito mortar and show its use on a specific example.

Válek, Jan; Skružná, Olga; Kozlovcev, Petr; Waisserová, J.; Wichterlová, Z.; Jiroušek, Josef
Ústav teoretické a aplikované mechaniky, 2019

Tomographical investigation of the historical metal bracelets
Kumpová, Ivana; Vopálenský, Michal
2019 - Czech
The work was focused on the method definition for the investigation of historical metal artifacts employing the X-ray tomography. Two metal bracelets made of brass and plated with silver were investigated in the laboratory. The goal was to determine the technology of manufacturing and damages, possible also to visualize the silver layer. Práce byla zaměřena na vytvoření metodiky využívající rentgenové (RTG) tomografické zobrazování pro průzkumy historických artefaktů na bázi kovů. V laboratoři byly touto metodou zkoumány dva kovové náramky z mosazi s postříbřeným povrchem. Průzkum byl proveden za účelem odhalení technologie výroby a případných poškození, případně řešení napojení stříbrné vrstvy. Keywords: X-ray tomography; investigation of historical objects; metal artifacts Available at various institutes of the ASCR
Tomographical investigation of the historical metal bracelets

The work was focused on the method definition for the investigation of historical metal artifacts employing the X-ray tomography. Two metal bracelets made of brass and plated with silver were ...

Kumpová, Ivana; Vopálenský, Michal
Ústav teoretické a aplikované mechaniky, 2019

Chemical and mineralogical analyses of plaster samples from State Castle Bečov
Slížková, Zuzana; Koudelková, Veronika; Kozlovcev, Petr; Šterner, Adam
2018 - Czech
Using chemical and microscopic analysis, it was determined that the analyzed sample of bedding mortar from the 13th century (Czech castle Bečov) is the air lime mortar with the quartz and silicate sand enriched by some content of slag grains. The internal plaster from the same building period of the castle was made using the lime-earthen mortar with predominantly silicate sand. The plaster contained an admixture of wood or plant particles, sawdust has been identified.\n\n Pomocí chemické a mikroskopické analýzy bylo určeno, že analyzovaný vzorek malty z 13. stol. je vápenná malta s převážně křemenným a silikátovým pískem a vnitřní omítka z 13. stol. byla provedena z malty vápenohliněné s převážně silikátovým plnivem. Omítka obsahuje příměs dřevěných či rostlinných částic, byly identifikovány piliny. Malta obsahuje kousky strusky. Keywords: chemical composition; survey; material characterization; binder; aggregate; historic plaster; historic render Available at various institutes of the ASCR
Chemical and mineralogical analyses of plaster samples from State Castle Bečov

Using chemical and microscopic analysis, it was determined that the analyzed sample of bedding mortar from the 13th century (Czech castle Bečov) is the air lime mortar with the quartz and silicate ...

Slížková, Zuzana; Koudelková, Veronika; Kozlovcev, Petr; Šterner, Adam
Ústav teoretické a aplikované mechaniky, 2018

Proposal for loading tests of bridges - simulation and laboratory experiments
Bayer, Jan; Urushadze, Shota; Černý, Miloš
2018 - English
A new dynamic load testing of bridges is proposed and theoretically investigated. A transient analysis of passing vehicle over a bridge in ANSYS and an analytical program in MATLAB for the transient solution of piecewise linear mechanical structures were developed to assess the effects of the proposed dynamic load on a bridge model. According to the first laboratory experiments, it seems that the proposed travelling impulse load could surpass some of the shortcomings and limitations of the currently applied methods of bridge testing. The investigation is a part of a project aimed at drive-by identification of dynamic properties of bridges and further experimental and analytical research will follow. Keywords: dynamic loading tests; transient analysis; vibrations; vehicle-bridge interaction Fulltext is available at external website.
Proposal for loading tests of bridges - simulation and laboratory experiments

A new dynamic load testing of bridges is proposed and theoretically investigated. A transient analysis of passing vehicle over a bridge in ANSYS and an analytical program in MATLAB for the transient ...

Bayer, Jan; Urushadze, Shota; Černý, Miloš
Ústav teoretické a aplikované mechaniky, 2018

Characterization of historical renders and plasters sampled from the Castle Freudenstein (also called Slikuv Castle), tower „Slikovka“, Ostroh nad Jachymovem (Zamecký vrsek u Jachymova)
Slížková, Zuzana; Frankeová, Dita; Koudelková, Veronika
2018 - Czech
SEM and SEM-EDS analyses was used for determination of renders and plasters microstructure and components Vzorky vnějších a vnitřních omítek byly zkoumány za účelem zjištění jejich struktury a chemického složení pomocí metod SEM a SEM-EDS Keywords: render; plaster; slag; cement; SEM-EDS analysis Available at various institutes of the ASCR
Characterization of historical renders and plasters sampled from the Castle Freudenstein (also called Slikuv Castle), tower „Slikovka“, Ostroh nad Jachymovem (Zamecký vrsek u Jachymova)

SEM and SEM-EDS analyses was used for determination of renders and plasters microstructure and components

Slížková, Zuzana; Frankeová, Dita; Koudelková, Veronika
Ústav teoretické a aplikované mechaniky, 2018

Footbridge in Radotín - wind load according to EN 1991-1-4 and wind tunnel experiments
Göringer, J.; Hračov, Stanislav; Macháček, Michael
2018 - Czech
Due to the atypical design of the footbridge in Radotín the procedures for evaluation of the force coefficients presented in EN 1991-1-4 were experimentally verified in the wind tunnel. For the lack of the information about the structure behaviour on the edge of the aerodynamic instability the critical velocity for flutter was experimentally verified as well. The paper presents comparison of the approaches from EN 1991-1-4 with the results of the experiment. S ohledem na atypickou konstrukci lávky v Radotíně bylo nutno v rámci statického ověření řešit nestandardní účinky zatížení větrem, kdy EN 1991-1-4 poskytuje pro takto atypické konstrukce jen málo podpory. Zatížení větrem u takovéto konstrukce nevystupuje pouze jako náhradní statický účinek, ale zejména je nutné posoudit případné ztráty aerodynamické stability. Příspěvek předkládá postup stanovení problematiky podle EN 1991-1-4 včetně porovnání s výsledky z větrného tunelu. Keywords: wind load; footbridge; wind tunnel experiments Available at various institutes of the ASCR
Footbridge in Radotín - wind load according to EN 1991-1-4 and wind tunnel experiments

Due to the atypical design of the footbridge in Radotín the procedures for evaluation of the force coefficients presented in EN 1991-1-4 were experimentally verified in the wind tunnel. For the lack ...

Göringer, J.; Hračov, Stanislav; Macháček, Michael
Ústav teoretické a aplikované mechaniky, 2018

Non-destructive survey of the oldest part of the castle in Telč
Drdácký, Miloš; Eisler, Marek; Lesák, Jaroslav; Válek, Jan; Skružná, Olga
2018 - Czech
Recent archaeological findings discovered at an excavation in the southeastern section of the small courtyard of the old palace at the state castle in Telč sparked interest in further exploring hidden structures below ground and within the existing masonry. Therefore, a non-destructive survey of structures hidden beneath the current level of the courtyard using ground-penetrating radar was conducted, as was a survey of the masonry within the old walls of the palace using thermography. Nedávné archeologické nálezy zjištěné kopanou sondou v jihovýchodní části 'Malého dvorku'\nstarého paláce státního zámku Telč vyvolaly zájem o prozkoumání skrytých stavebních konstrukcí\npod terénem i ve stávajícím zdivu. Byl proto realizován nedestruktivní průzkum jednak stavebních konstrukcí skrytých pod současnou úrovní 'Malého dvorku' starého hradu v Telči pomocí zemního radaru, jednak průzkum charakteru zdiva stěn starého paláce pomocí termovize. Keywords: cultural heritage; non-destructive testing; ground-penetrating radar; thermography Available at various institutes of the ASCR
Non-destructive survey of the oldest part of the castle in Telč

Recent archaeological findings discovered at an excavation in the southeastern section of the small courtyard of the old palace at the state castle in Telč sparked interest in further exploring hidden ...

Drdácký, Miloš; Eisler, Marek; Lesák, Jaroslav; Válek, Jan; Skružná, Olga
Ústav teoretické a aplikované mechaniky, 2018

Basic biomechanical characterization of polyurethane based artificial cancellous structures
Šleichrt, Jan; Kytýř, Daniel; Pithartová, Kateřina; Senck, S.; Fürst, D.; Schrempf, A.
2018 - English
The main goal of this study is to validate elementary mechanical parameters of a newly designed open-cell foam. The purpouse for investigating artificial material is to approach the properties of the human bone in the case of its adequate replacement. Investigated material can be also used as an artificial bone to train surgical procedures and to improve the skills of the surgeons. Four sets of the foam with different chemical composition were subjected to an uniaxial quasi-static loading to describe basic mechanical behaviour of these samples. Based on these experiments, the stress-strain diagrams were created as a comparative tool including calculation of the effective Young’s modulus. The acquired knowledges will be used as input parameters of a follow-up study aimed at describing the morphology of presented structures and their response to mechanical experiments. A distortion effect of porosity on the results is not considered in this study. Keywords: polyurethane foam; artificial bone; uniaxial loading; digital image correlation Available at various institutes of the ASCR
Basic biomechanical characterization of polyurethane based artificial cancellous structures

The main goal of this study is to validate elementary mechanical parameters of a newly designed open-cell foam. The purpouse for investigating artificial material is to approach the properties of the ...

Šleichrt, Jan; Kytýř, Daniel; Pithartová, Kateřina; Senck, S.; Fürst, D.; Schrempf, A.
Ústav teoretické a aplikované mechaniky, 2018

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