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Long term optical monitoring technique of displacement fields based on ArUco markers
Kunecký, Jiří
2022 - English
In structural engineering it is often needed to measure tiny displacements of parts of the structure extremely precisely. For such a purpose it is often needed to use some type of sensor attached to the surface of the structure. This paper presents a new technique which simply uses computer vision libraries to measure displacement of markers originally developed for robotics. Such analysis can be under specific circumstances (2D planar movement) valid if we compare two images taken at different times with the same camera. Main advantage of this method is simplicity of use and low cost of markers, which can be printed in a standard office laser printer. The resolution (error) can be for standard cameras around 0.1 pixel. The method is especially developed for research of timber frames/joints behavior in real structures, because displacements of joints in creep or under load can reach an amplitude which is perfectly detectable by this method.
Keywords:
displacement measurement; long-term monitoring; ArUco markers
Available at various institutes of the ASCR
Long term optical monitoring technique of displacement fields based on ArUco markers
In structural engineering it is often needed to measure tiny displacements of parts of the structure extremely precisely. For such a purpose it is often needed to use some type of sensor attached to ...
Zpráva o výsledcích chemické a mineralogické analýzy vzorku omítky z objektu: Zámek Opočno
Frankeová, Dita; Bauerová, Pavla; Slížková, Zuzana
2022 - Czech
V rámci stavebně-technického průzkumu byl proveden rozbor vzorků historických omítek s využitím termické analýzy a SEM‐EDS analýzy. Byla provedena charakterizace plniva a složek pojiva malt a jejich povrchových úprav. Výsledky průzkumných prací byly použity jako podklad pro návrh rekonstrukce objektu. An analysis of historical plaster was carried out using thermal analysis and SEM-EDS analysis. The binders and aggregates of mortars and their surface treatments were characterized. The survey results were used for the design of the repair mortars.
Keywords:
TGA; SEM/EDS; binder characterization
Available at various institutes of the ASCR
Zpráva o výsledcích chemické a mineralogické analýzy vzorku omítky z objektu: Zámek Opočno
V rámci stavebně-technického průzkumu byl proveden rozbor vzorků historických omítek s využitím termické analýzy a SEM‐EDS analýzy. Byla provedena charakterizace plniva a složek pojiva malt a jejich ...
Analysis of van der Pol equation on slow time scale for combined random and harmonic excitation
Náprstek, Jiří; Fischer, Cyril
2022 - English
Vortex shedding represents one of the most important processes that constantly attract the attention of experimental and theoretical research. A number of non-linear effects arise from the fluid-structure interaction. The non-stationary response in the vicinity of the lock-in region has a quasi-periodic character, beating frequency of which varies considerably with the distance from the lock-in frequency. This property is significantly affected by the assumption of combined random and harmonic excitation. This paper describes several details that contribute to the probabilistic characteristics of the system on a time-slow scale using partial response amplitudes.
Keywords:
SDOF oscillator; slow-time system; Fokker-Planck equation
Available at various institutes of the ASCR
Analysis of van der Pol equation on slow time scale for combined random and harmonic excitation
Vortex shedding represents one of the most important processes that constantly attract the attention of experimental and theoretical research. A number of non-linear effects arise from the ...
Construction of the Lyapunov function reflecting the physical properties of the model
Náprstek, Jiří; Fischer, Cyril
2022 - English
Practical experience shows that the random excitation component can affect the system response and its dynamic stability not only negatively but also positively. Such mechanisms are usually developed heuristically and are often not sufficiently justified theoretically. The paper presents a possibility of using the properties of first integrals for the construction of a Lyapunov function for the analysis of a dynamic system stability in the stochastic domain. In such case, the Lyapunov function itself contains information on the examined system and, consequently, it is able to provide a more detailed insight into the system stability properties. The procedure is illustrated by a nonlinear SDOF example.
Keywords:
Lyapunov function; stability; spherical pendulum
Available at various institutes of the ASCR
Construction of the Lyapunov function reflecting the physical properties of the model
Practical experience shows that the random excitation component can affect the system response and its dynamic stability not only negatively but also positively. Such mechanisms are usually developed ...
Zřícenina středověkého hradu a moderní technologie pro bezpečnou správu
Novotný, Jakub
2022 - Czech
Tématem příspěvku je vztah torzální architektury a moderních technologií. Nejprve je stručně představen dokument Report assessing innovative restoration techniques, technologies and materials used in conservation, který poskytuje přehled nejpoužívanějších technik, technologií a materiálů pro průzkumu a ochranu tohoto typu památek. Dále příspěvek přibližuje průběh a výsledky projektu regionální spolupráce Technologický výzkum zříceniny hradu Štamberk v širším kontextu regionu s důrazem na použití moderních technologií. The topic of the paper is the relationship between torsional architecture and modern technologies. First, the Report assessing innovative restoration techniques, technologies and materials used in conservation is briefly presented, which provides an overview of the most used techniques, technologies and materials for the exploration and protection of this type of monuments. Furthermore, the paper provides an overview of the progress and results of the regional cooperation project Technological research of the Štamberk castle ruins in the wider context of the region with an emphasis on the use of modern technologies.
Keywords:
ruin; modern technologies; Štamberk Castle; conservation
Available at various institutes of the ASCR
Zřícenina středověkého hradu a moderní technologie pro bezpečnou správu
Tématem příspěvku je vztah torzální architektury a moderních technologií. Nejprve je stručně představen dokument Report assessing innovative restoration techniques, technologies and materials used in ...
Analytical model of joint loaded perpendicular to wooden grain
Hataj, M.; Pošta, J.; Hasníková, Hana; Kunecký, Jiří
2022 - English
Computing models for structural behaviour and determination of traditional timber butt joints using analytical relations are presented in this paper. A component method is the base of the computing technique introduced herein. This method is usually used for steel joint design. The component method is based on dividing a joint into individual components. These are defined by partial joint component stiffness. An analytical solution includes a subsidence effect of wooden material close to compressive loading. Analytical computation results are compared with the experimental outputs. A design procedure according to Eurocode 5 for a load capacity determination of perpendicularly loaded structural elements is stated in the paper.
Keywords:
analytical models; load capacity; butt joint; carpentry; timber structures
Available at various institutes of the ASCR
Analytical model of joint loaded perpendicular to wooden grain
Computing models for structural behaviour and determination of traditional timber butt joints using analytical relations are presented in this paper. A component method is the base of the computing ...
Wooden construction of the movable roof of the garden pavilion in Český Krumlov castle
Bláha, Jiří; Kloiber, Michal
2022 - English
A remarkable technical monument is situated on one of the garden terraces belonging to the state castle and chateau in Český Krumlov. The umbrella-shaped roof of the lookout pavilion can be lifted about a meter above the masoned parapet allowing the visitor a beautiful view of the World Heritage town panorama when the weather is fine. In windy conditions or in case of heavy rain the roof could be lowered and the pavilion thus closed. The lifting is operated by means of a wooden lever mechanism with a counterweight box hidden in the basement level of the building. The unique construction was built in 1823 and needed to be partially altered in 1830-1835. However, since then it has been preserved in a surprisingly authentic state even allowing practical demonstrations of its original function. Prior to recent repairs in 2016, a comprehensive non-destructive survey was conducted. The extent of the damage discovered was determined by measuring the speed of elastic wave propagation using stress waves (Fakkop 2D) and measuring the mechanical resistance when drilling with a thin bit using resistance micro-drilling (Resistograph). Another method based on loading timber by means of a\nminiature loading jack inserted into a drilled hole was selected to determine the current mechanical properties.
Keywords:
lookout pavilion; gazebo; non-destructive testing; roof; timber; wood
Available at various institutes of the ASCR
Wooden construction of the movable roof of the garden pavilion in Český Krumlov castle
A remarkable technical monument is situated on one of the garden terraces belonging to the state castle and chateau in Český Krumlov. The umbrella-shaped roof of the lookout pavilion can be lifted ...
Chemická a mikrostrukturní analýza vzorku omítky ze zámku Sychrov – oprava Bretaňské věže
Slížková, Zuzana; Frankeová, Dita; Bauerová, Pavla; Náhunková, Pavla
2022 - Czech
Analyzovaná malta obsahuje 76,5 % hm. křemičitého písku a 23,5 % hm. tvoří vápenné pojivo - jedná se o silně hydraulické vápno. Kamenivo malty je tvořeno v naprosté většině křemenem. Hydraulicitu obsaženého vápenného pojiva dokazuje jednak přítomnost belitických slínků, silně nehomogenní mikrostruktura (typické střídání hutných, Ca nabohacených částí a poréznějších dekalcifikovaných oblastí) a dále přítomnost silikátových složek v různé míře zreagování. Nabízí se domněnka, že použité hydraulické pojivo mohlo být připraveno uměle smícháním vápna s hydraulickou silikátovou přísadou. The analysed mortar contains 76.5% by weight quartz sand and 23.5% wt. the lime binder - it is highly hydraulic lime. The aggregate of the mortar is made up mostly of quartz. The hydraulicity of the contained lime binder is evidenced by the presence of belitic clinkers, a strongly inhomogeneous microstructure (typical alternation of dense, Ca-enriched parts and more porous decalcified areas) and the presence of silicate components in varying degrees of reaction. It is suggested that the hydraulic binder used could have been artificially prepared by mixing lime with a hydraulic silicate additive.
Keywords:
historic mortar; lime mortar; chemical analysis; SEM-EDS; termal analysis
Available at various institutes of the ASCR
Chemická a mikrostrukturní analýza vzorku omítky ze zámku Sychrov – oprava Bretaňské věže
Analyzovaná malta obsahuje 76,5 % hm. křemičitého písku a 23,5 % hm. tvoří vápenné pojivo - jedná se o silně hydraulické vápno. Kamenivo malty je tvořeno v naprosté většině křemenem. Hydraulicitu ...
Průzkum terénu a konstrukcí pod podlahou kostela Matky Boží na Starém Městě v Telči
Válek, Jan; Kotková, Kristýna; Kozlovcev, Petr
2022 - Czech
Byl realizován nedestruktivní průzkum stavebních konstrukcí skrytých pod současnou úrovní kostela Matky Boží na Starém Městě v Telči pomocí zemního radaru. Průzkum odhalil výskyt skrytých konstrukcí, které mají vztah k současnému pojetí kostela a jeho stavebního řešení. A non-destructive survey of the building structures hidden under the current level of the Church of the Mother of God in the Old Town of Telč was carried out using ground-penetrating radar. The survey revealed the occurrence of hidden constructions that are related to the current concept of the church and its construction solution.
Keywords:
ground penetrating radar (GPR); cultural heritage; non-destructive testing
Available at various institutes of the ASCR
Průzkum terénu a konstrukcí pod podlahou kostela Matky Boží na Starém Městě v Telči
Byl realizován nedestruktivní průzkum stavebních konstrukcí skrytých pod současnou úrovní kostela Matky Boží na Starém Městě v Telči pomocí zemního radaru. Průzkum odhalil výskyt skrytých konstrukcí, ...
Stone surface topography of Prague historic monuments over the centuries
Kovářová, K.; Cihla, Michal; Malát, R.; Semerád, M.; Tryml, M.
2022 - English
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every period. Each work has its own unique pattern and bears traces of individual stonemason workshops, tradition, etc. The study of building stone cutting is based on evolving methods of mechanoscopy and analytical traceology. Stone traceology deals with traces in material and the subsequent reconstruction of tools and the processes of stoneworking. The interpretation of data in terms of determining the actual trace is called a mechanoscopy. When studying a stone surface, the latest 3D modelling technology is used with subsequent analyses by means of Global Mapper software. The use of these methods enables reconstruction of the craftsman’s tools. The presented article is an extract of a study that systematically maps the stone cutting work in the territory of Prague from the oldest buildings to the present day. For example, stonework in 9th century Prague was gradually evolving from simple stone block modelling to sophisticated cutting of blocks in the 12th century. This information can be very useful in the process of monument care.
Keywords:
stone topography; Prague; craftmanship; stonemason tool; tool traces
Available at various institutes of the ASCR
Stone surface topography of Prague historic monuments over the centuries
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every ...
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