No (14409)
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Průzkum spojení kamenných bloků ozdobného „klenutíʺ průhledů cimbuří Prašné brány v Praze
Válek, Jan; Kotková, Kristýna; Kozlovcev, Petr
2024 - Czech
Průzkum napojení kamenných prvků cimbuří Prašné brány v Praze pomocí zemního radaru. Cílem je ověření existence propojovacích prvků ve styčné/ložné spáře mezi kameny „zaklenutí“ průhledů cimbuří a bočními opěrami. Interpretace radargramů ukazuje na kamenické spojky. Malta obsahuje železitou příměs. Survey of the connection of the stone elements of the Powder Tower in Prague using ground penetrating radar. The aim is to verify the existence of connecting elements with the „archingʺ of the battlements and side supports. Interpretation of the radargrams points to a stonemasonry dowels. The mortar contains an iron admixture.
Keywords:
ground penetrating radar; masonry joints; NDT survey
Available at various institutes of the ASCR
Průzkum spojení kamenných bloků ozdobného „klenutíʺ průhledů cimbuří Prašné brány v Praze
Průzkum napojení kamenných prvků cimbuří Prašné brány v Praze pomocí zemního radaru. Cílem je ověření existence propojovacích prvků ve styčné/ložné spáře mezi kameny „zaklenutí“ průhledů cimbuří a ...
Materiálová analýza vzorků malt z archeologického kontextu baziliky sv. Václava ve Staré Boleslavi
Válek, Jan; Kozlovcev, Petr; Svorová Pawełkowicz, Sylwia; Kotková, Kristýna
2024 - Czech
Vzorky malt byly popsány pomoci optické mikroskopie a SEM-EDS. Cílem studie bylo jejich vzájemné porovnání. Všechny tři vzorky mají podobnou strukturu i materiálové složení. Surovinou pro výrobu vápna byl jemnozrnný sedimentární vápenec s vysokým obsahem CaCO3. Vápenná matrice má charakter vzdušného vápna. Kromě vápenného pojiva se vyskytuje též prachovojílové pojivo. To je odděleno od vápenného. Zrna písku jsou obalena vápenným pojivem a v meziprostoru je prachovojílová výplň, což ukazuje na přidání této složky jako příměsi do malty až během použití při stavbě. Použitý písek odpovídá místním poměrům, a to jak eolickým pískům (spraším a sprašovým sedimentům) s dominantním výskytem opracovaných křemenných klastů, tak částečně i sedimentům fluviálního původu (zde se jedná především o litoklasty transportované na větší vzdálenost). The mortar samples were characterized by optical microscopy and SEM-EDS. The aim of the study was to compare them with each other. All three samples have similar structure and material composition. The raw material for the lime was fine-grained sedimentary limestone with high CaCO3 content. The lime matrix has the character of air lime. In addition to the lime binder, there is also a mud-clay binder. This is separate from the lime binder. The sand grains are surrounded by the lime binder and there is a mud-clay filler in the intermediate space, indicating that this component was added as an admixture to the mortar only during use in construction. The sand used corresponds to the local conditions, both to aeolian sands (loess and loess sediments) dominated by worked quartz clasts and, in part, to sediments of fluvial origin (here mainly lithoclasts transported over a greater distance).
Keywords:
historic mortar; microscopy; lime binder; earth binder
Available at various institutes of the ASCR
Materiálová analýza vzorků malt z archeologického kontextu baziliky sv. Václava ve Staré Boleslavi
Vzorky malt byly popsány pomoci optické mikroskopie a SEM-EDS. Cílem studie bylo jejich vzájemné porovnání. Všechny tři vzorky mají podobnou strukturu i materiálové složení. Surovinou pro výrobu vápna ...
Testování susceptibility materiálů lineru kompozitních nádob na chladivové plyny (refrigeranty)
Šperl, Martin; Vála, Ondřej; Bejdl, Jan
2024 - Czech
Výzkumná studie o vlivu atmosféry tlakového chladiva na některé materiálové vlastnosti linerů kompozitních nádob Research study about the influences of pressurized refrigerants atmosphere to some material properties of liners
Keywords:
composite vessel; refrigerant; polymer liner; strength
Available at various institutes of the ASCR
Testování susceptibility materiálů lineru kompozitních nádob na chladivové plyny (refrigeranty)
Výzkumná studie o vlivu atmosféry tlakového chladiva na některé materiálové vlastnosti linerů kompozitních nádob...
Experimentální výzkum mechanických a lomověmechanických vlastností potrubí produktovodu DN 150 Bělčice – Třemošná s označením L186, ocel 11 353
Gajdoš, Lubomír; Šperl, Martin; Šorm, Filip; Bejdl, Jan
2024 - Czech
Experimentální výzkum mechanických a lomově-mechanických vlastností trubních vzorků z produktovodu DN 150. Kromě základních statických zkoušek a zkoušek na určení lomové houževnatosti bylo součástí výzkumu i určení kinetiky růstu únavových trhlin vč. analýzy kritické velikosti trhlin. Experimental research of mechanical and fracture mechanical properties of the pipe specimens taken from oil pipeline DN 150. In addition to basic static tests and fracture toughness tests, the research also included the determination of the kinetic of fatigue crack growth, incl. analysis of critical crack size.
Keywords:
J integral; pipeline; toughness; crack
Available at various institutes of the ASCR
Experimentální výzkum mechanických a lomověmechanických vlastností potrubí produktovodu DN 150 Bělčice – Třemošná s označením L186, ocel 11 353
Experimentální výzkum mechanických a lomově-mechanických vlastností trubních vzorků z produktovodu DN 150. Kromě základních statických zkoušek a zkoušek na určení lomové houževnatosti bylo součástí ...
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Švábenská, Eva; Roupcová, Pavla; Havlíček, Lubomír; Schneeweiss, Oldřich
2024 - English
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are Fe-Ni-based \nalloys, in particular, the Fe50Ni50 L10 phase (tetrataenite), which has a great perspective for producing hard \nmagnetic materials. Our study explores a promising method for preparing nanoparticles of Fe-Ni alloy from an \niron-nickel oxalate precursor. The coprecipitation method was employed to prepare oxalate precursors, \nfollowed by controlled thermal decomposition in a reducing hydrogen atmosphere. The morphology and \nproperties of the resulting particles were analysed using scanning electron microscopy (SEM) coupled with \nenergy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and \nmagnetic measurements.\nThe SEM analysis revealed that the particles have approximately cube-shaped unit cell morphology with a\nsize in a range of 1 - 2 μm. Upon annealing, the samples contain multiple phases with varying Fe-Ni content.\nMagnetic measurements confirmed the formation of magnetically suitable Fe-Ni phases in the samples after \nannealing. Mössbauer spectroscopy emerged as a highly effective method for characterizing individual phases \nof the Fe-Ni system.
Keywords:
Magnetic materials; thermal decomposition; Mössbauer spectroscopy
Available at various institutes of the ASCR
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are ...
EFFECT OF OXIDE DISPERSION ON ELECTRIC CONDUCTIVITY OF ROTARY SWAGED POWDER-BASED COPPER COMPOSITES
Kunčická, Lenka; Benč, Marek; Kačor, P.; Marek, M.
2024 - English
Copper is a very popular electro-conductive material, however, the mechanical properties of pure Cu are low. They can be typically improved by (micro)alloying, or via structure modifications introduced by optimized deformation and thermomechanical treatments. Designing a Cu-based composite, possibly strengthened by a dispersion of fine oxides, is another way how to favourably improve the strength properties of Cu. In this study, we performed mechanical alloying of a Cu powder with a powder of Al2O3 oxide, which is known to have strengthening effects on metallic materials. After mixing, we sealed the powder mixture into evacuated tubular Cu containers (i.e. cans). As for the consolidation procedure, we applied direct consolidation of the canned powders via the intensive plastic deformation method of rotary swaging, performed under warm conditions. Subsequently, we subjected the swaged conductors to measurements of electric conductivity and detailed structure observations. The results revealed that the applied swaging ratio was sufficient to fully consolidate the canned powders as the final conductor was unrecognizable from a cast alloy from the viewpoints of visual and structure assessment. In other words, the structure did not exhibit any voids or remnants of unconsolidated powder particles. The observed fine grains with homogeneous dispersion of Al2O3 oxide particles provided improvement of the mechanical properties, as proven by microhardness measurements. Moreover, the electric properties remained favourable.
Keywords:
mechanical-properties; extrusion; Copper; oxide dispersion; electric conductivity; rotary swaging; microstructure
Available at various institutes of the ASCR
EFFECT OF OXIDE DISPERSION ON ELECTRIC CONDUCTIVITY OF ROTARY SWAGED POWDER-BASED COPPER COMPOSITES
Copper is a very popular electro-conductive material, however, the mechanical properties of pure Cu are low. They can be typically improved by (micro)alloying, or via structure modifications ...
Modification of cooling system for laboratory measurement of rotor blade vibration
Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Voronova, Evgeniya; Mekhalfia, Mohammed Lamine
2024 - English
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and the expected higher operating load planned for the new wheel, the cooling system was modified at the same time. The paper describes the main effort in this direction and the results that clarify the previous damage of the measuring device.
Keywords:
blade; vibration; cooling system; measurement; laboratory
Available at various institutes of the ASCR
Modification of cooling system for laboratory measurement of rotor blade vibration
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and ...
DYNAMICS OF MACHINES AND MECHANICAL SYSTEMS WITH INTERACTIONS : PROCEEDINGS DYMAMESI 2024
Zolotarev, Igor; Pešek, Luděk; Kozień, M. S.
2024 - English
The aim of the DYMAMESI is to facilitate the exchange of up to date information and knowledge among specialists in structural and multibody dynamics, in coupled interacting systems as aero-elasticity, hydro-elasticity, biomechanics, systems with feedbacks and mechatronics. In 2023 will be hosted by Cracow University of Technology, Institute of Applied Mechanics, Section of Dynamics of Systems.
Keywords:
dynamics; vibrations of mechanical systems; vibrodiagnostics; energy transformations
Available at various institutes of the ASCR
DYNAMICS OF MACHINES AND MECHANICAL SYSTEMS WITH INTERACTIONS : PROCEEDINGS DYMAMESI 2024
The aim of the DYMAMESI is to facilitate the exchange of up to date information and knowledge among specialists in structural and multibody dynamics, in coupled interacting systems as aero-elasticity, ...
ENHANCING WELD JOINT INTEGRITY IN S460 HIGH-STRENGTH STEEL PLATES: AN EXPERIMENTAL APPROACH
Al Khazali, Mohammad Sami; Malíková, Lucie; Křivý, V.; Seitl, Stanislav
2024 - English
Exploring S460 steel, this research assesses weld toe microstructure and fatigue. It finds that welding affects \nhardness of welded area and fatigue life. These insights are crucial for structural engineering, optimizing welding \npractices for longevity. \nTests confirm increased weld toe hardness correlates with fatigue resistance. This informs design strategies, \nensuring bridge safety under cyclic loads. The study advances understanding of HSS behaviour, influencing future \nwelding techniques.
Keywords:
High-strength steel; weld's toe; cruciform joints; S460; fatigue behaviour
Available at various institutes of the ASCR
ENHANCING WELD JOINT INTEGRITY IN S460 HIGH-STRENGTH STEEL PLATES: AN EXPERIMENTAL APPROACH
Exploring S460 steel, this research assesses weld toe microstructure and fatigue. It finds that welding affects \nhardness of welded area and fatigue life. These insights are crucial for structural ...
Experimentální výzkum mechanických a lomově-mechanických vlastností ocelí P355, L360NB a 42CrMo4 exponovaných ½ roku v tlakové vodíkové atmosféře
Šperl, Martin; Gajdoš, Lubomír; Šorm, Filip; Bejdl, Jan
2024 - Czech
Výzkum vlivu vodíku na mechanické a lomově mechanické vlastnosti daných ocelí v závislosti na čase expozice. Research of the influence of hydrogen on the mechanical and fracture mechanical properties of specific steels depending on the exposition time.
Keywords:
pipeline steel; hydrogen exposition; fracture toughness; notch toughness
Available at various institutes of the ASCR
Experimentální výzkum mechanických a lomově-mechanických vlastností ocelí P355, L360NB a 42CrMo4 exponovaných ½ roku v tlakové vodíkové atmosféře
Výzkum vlivu vodíku na mechanické a lomově mechanické vlastnosti daných ocelí v závislosti na čase expozice....
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