No (20983)
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20983
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A short study on self-balancing of vertical rotors mounted in passive contactless bearings
Zapoměl, Jaroslav; Kozánek, Jan
2023 - English
Energy losses and wear of the support elements of high-speed rotors can be reduced by mounting the rotors in stable passive contactless bearings, the operation of which is based on magnetic levitation. The goal of the conducted research was to investigate applicability of selfbalancing device added to vertical rotors supported by bearings showing low stiffness and damping, which is a specific property of passive magnetic bearings. This paper deals with applicability and efficiency of self-balancing devices added to vertical rotors supported by bearings having very low stiffness and damping, which corresponds to the properties of magnetic frictionless bearings.
Keywords:
self-balancing of rotors; passive contactless bearings; the influence of external damping
Available at various institutes of the ASCR
A short study on self-balancing of vertical rotors mounted in passive contactless bearings
Energy losses and wear of the support elements of high-speed rotors can be reduced by mounting the rotors in stable passive contactless bearings, the operation of which is based on magnetic ...
Na jedno aneb pozvánka na cestu po hospodách a jejich názvech
Šipková, Milena
2023 - Czech
Přednáška se zabývá názvy hostinců, sloužících jako centrum společenského života na Moravě a ve Slezsku. The lecture deals with the names of the inn, serving as a center of social life in Moravia and Silesia.
Keywords:
Czech language; nominal names; social life; names of the pubs; Moravia; Silesia
Available at various institutes of the ASCR
Na jedno aneb pozvánka na cestu po hospodách a jejich názvech
Přednáška se zabývá názvy hostinců, sloužících jako centrum společenského života na Moravě a ve Slezsku....
Krajina, sídla a památky v deníku Jiřího II. Buquoye z italské cesty v letech 1839 a 1840
Binder, Filip
2023 - Czech
Studie se zabývá cestou hraběte Jiřího II. Buquoye do Itálie, která se uskutečnila v letech 1839 a 1840, a zaměřuje se na jeho reflexi krajiny, zahrad, sídel a památek v jeho cestovním deníku. The paper deals with the journey of Georg II Buquoy to Italy which took place in 1839 and 1840 and focuses on his reflection of landscape, gardens, settlements and monuments in his travel diary.
Keywords:
nobility; history of travelling; Italy
Available at various institutes of the ASCR
Krajina, sídla a památky v deníku Jiřího II. Buquoye z italské cesty v letech 1839 a 1840
Studie se zabývá cestou hraběte Jiřího II. Buquoye do Itálie, která se uskutečnila v letech 1839 a 1840, a zaměřuje se na jeho reflexi krajiny, zahrad, sídel a památek v jeho cestovním deníku....
Dynamic tensile experiments of hard rubber on instron test machine under finite deformations
Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Šnábl, Pavel
2023 - English
This paper deals with the first experimental tests of hard rubbers under tensile harmonic loading on the axial-torsional servohydraulic Instron 8852 test machine. The objective of these experiments on cylindrical rubber specimens on this machine is to obtain stress-strain curves of rubber specimens, first considering uniaxial finite longitudinal strains for a single load cycle. Next, the hysteresis loops and their skeleton curves are compared for two selected strain measures as a function of their conjugate stress. It is shown how to obtain the dependence between elongation in the axial direction and constriction in the radial direction, which is used to determine the Cauchy stress in this configuration.
Keywords:
uniaxial harmonic loading; finite deformation; second Piola-Kirchhoff stress; hysteresis loop; Green-Lagrange strain tensor
Available at various institutes of the ASCR
Dynamic tensile experiments of hard rubber on instron test machine under finite deformations
This paper deals with the first experimental tests of hard rubbers under tensile harmonic loading on the axial-torsional servohydraulic Instron 8852 test machine. The objective of these experiments on ...
Identification of quasiperiodic processes in the vicinity of the resonance
Fischer, Cyril; Náprstek, Jiří
2023 - English
In nonlinear dynamical systems, strong quasiperiodic beating effects appear due to combination of self-excited and forced vibration. The presence of symmetric or asymmetric beatings indicates an exchange of energy between individual degrees of freedom of the model or by multiple close dominant frequencies. This effect is illustrated by the case of the van der Pol equation in the vicinity of resonance. The approximate analysis of these nonlinear effects uses the harmonic balance method and the multiple scale method.
Keywords:
dynamical systems; quasiperiodic response; van der Pol equation
Available at various institutes of the ASCR
Identification of quasiperiodic processes in the vicinity of the resonance
In nonlinear dynamical systems, strong quasiperiodic beating effects appear due to combination of self-excited and forced vibration. The presence of symmetric or asymmetric beatings indicates an ...
Laboratory X-ray imaging in material sciences
Koudelka_ml., Petr; Kytýř, Daniel; Jiroušek, O.
2023 - English
In recent decades, X-ray imaging and computed (micro)tomography (XCT) in particular have become common tools for volumetric inspection, visualization, and analysis of internal structure in materials from various fields [1]. In this lecture, we will explore various applications of laboratory X-ray imaging chains utilizing the combination of tomographical imaging with mechanical, thermal, or chemical loading of the irradiated sample in a so-called time-resolved imaging allowing for unprecedented insight into different phenomena driving fundamental processes encountered in various fields of material science. We will show that failure processes in engineering or geological materials [2] can be thoroughly studied by synergy of information from radiographical imaging and other methods including acoustic emission detection and optical measurements via high-speed visible-spectrum and thermal-imaging cameras, where the radiography provides important spatial information regarding deformation processes evolving within the tested samples that could not be obtained otherwise. The state-of-the-art the laboratory based imaging chains for investigation of dynamic response of materials under loading will be also discussed including high speed X-ray radiography utilizing a powerful X-ray source during high velocity impact as an approach suitable for inspection of an impacted sample. As an alternative to both conventional high-power sources and accelerator facilities, capabilities of a flash X-ray system developed primarily for in-situ ballistics research providing very short bursts of an extremely powerful intermittent X-ray radiation with a typical duration of dozens of nanoseconds will be shown.
Keywords:
X-ray imaging; material characterization; mechanical properties
Available at various institutes of the ASCR
Laboratory X-ray imaging in material sciences
In recent decades, X-ray imaging and computed (micro)tomography (XCT) in particular have become common tools for volumetric inspection, visualization, and analysis of internal structure in materials ...
Vowel length in infant-directed speech: the realisation of short-long contrasts in Czech IDS
Svoboda, Michaela; Chládková, Kateřina; Kocjančič Antolík, T.; Paillereau, Nikola; Slížková, P.
2023 - English
When interacting with young children, talkers across many languages use a speech style that reflects positive affect, draws infants' attention, and supposedly facilitates language acquisition. As for the latter, a well-documented feature of infant-directed speech is an exaggeration of spectrally-cued vowel contrasts. Here we tested whether talkers exaggerate also durationally cued contrasts. Sixty-three mothers, native speakers of Czech, were recorded while playing with their infant (4- to 10-month-olds, IDS) and while speaking to an adult (ADS). The durations of the five Czech phonemically short vowels were compared to their long counterparts. Vowel duration (normalised for word duration) was longer in IDS than in ADS more for phonemically long vowels at the younger infant ages, indicating a developmentally specific early exaggeration of length contrasts in Czech infant-directed speech. The present finding suggests that in a language with phonemic length, caregivers' realisation of speech sounds may go beyond merely being longer and slower overall.
Keywords:
infant-directed speech; vowel length; development of early input; Czech
Available on request at various institutes of the ASCR
Vowel length in infant-directed speech: the realisation of short-long contrasts in Czech IDS
When interacting with young children, talkers across many languages use a speech style that reflects positive affect, draws infants' attention, and supposedly facilitates language acquisition. As for ...
Hybridní svařování laser-MIG/MAG na ÚPT
Mrňa, Libor; Novotný, Jan; Šebestová, Hana; Znášik, Samuel; Gross, Jan; Harašta, Jiří
2023 - Czech
Častým nedostatkem laserových svarů je jejich neúplné vyplnění, protože se laserem obvykle svařuje bez přídavného materiálu. Při hybridním svařování laser-MIG/MAG vytváří laserový svazek tavnou lázeň, do které je elektrickým obloukem dodáván přídavný materiál. Synergické působení obou zdrojů umožňuje dosažení hlubokého štíhlého svaru s požadovaným převýšením. Příspěvek seznamuje s problematikou integrace jednotlivých systémů, a představuje dosud provedené experimenty. Laser welds usually suffer from underfill defects because the welding is usually made without a filler wire. During the hybrid laser-MIG/MAG welding, the laser beam forms the melt pool, and the arc simultaneously delivers melted filler wire. The synergic interaction of both heat sources allows deeper penetration while the weld face is sufficiently filled and has the prescribed geometry. This contribution reports the issues of individual systems integration and presents already-made experiments.
Keywords:
laser welding; hybrid welding; weld; underfill; synergy
Available at various institutes of the ASCR
Hybridní svařování laser-MIG/MAG na ÚPT
Častým nedostatkem laserových svarů je jejich neúplné vyplnění, protože se laserem obvykle svařuje bez přídavného materiálu. Při hybridním svařování laser-MIG/MAG vytváří laserový svazek tavnou lázeň, ...
Odkud pochází voda v Plešném jezeře?
Kopáček, Jiří; Porcal, Petr
2023 - Czech
Aplikace tří metod k odhadu podílu podzemní vody ve vodní bilanci Plešného jezera. Application of three approaches to estimate the contribution of groundwater in the water balance of Plešné Lake.
Keywords:
lake; groundwater contribution; isotopes
Available at various institutes of the ASCR
Odkud pochází voda v Plešném jezeře?
Aplikace tří metod k odhadu podílu podzemní vody ve vodní bilanci Plešného jezera.
Application of three approaches to estimate the contribution of groundwater in the water balance of Plešné Lake.
On jest figura neb obraz kostela a chrámu duchovního, jenž je tělo naše. Chrám jako metafora
Havelka, Tomáš
2023 - Czech
Příspěvek se zabývá zejména literárními metaforizacemi křesťanského chrámu ve třech základních typologiích chrámu, a to jako metafory lidského těla, prefigurativního vzoru dějin Šalomounova chrámu přenášeným na dějiny církevních obcí a metaforou vědění. Chrám není v žádném náboženství jen místo shromáždění věřících, odjakživa byl chápán jako transcendentní brána spojující stvořený svět a Boží přítomnost. Reprezentoval „střed světa“ a postupně přebíral různé typologické a metaforické realizace: Šalamounova chrámu, nebeského Jeruzaléma, božského kruhu, jehož střed je všude a obvod nikde aj. To vedlo k naplňování různých dispozic. Na druhou stranu jsou ale také v literatuře 17. a 18. století přítomné pozoruhodné postupy, interpretující chrám obráceně, totiž jako antropomorfní metaforu lidského těla, nejvýraznějším způsobem u J. F. Beckovského. The paper mainly deals with literary metaphorizations of the Christian temple in three basic typologies of the temple, as metaphors of the human body, a prefigurative pattern of the history of Solomon’s temple transferred to the history of church communities and the metaphor of knowledge. In any religion, the temple is not just a place for believers to gather, it has always been understood as a transcendent gate connecting the created world and God’s presence. It represented the “center of the world” and gradually took on various typological and metaphorical realizations: Solomon’s temple, the heavenly Jerusalem, the divine circle, whose center is everywhere and whose circumference is nowhere. This led to the fulfillment of various dispositions. On the other hand, remarkable practices are also present in the literature of the 17th and 18th centuries, interpreting the temple in the opposite way, namely as an anthropomorphic metaphor of the human body, most prominently in the case of J.F. Beckovský.
Keywords:
temple; metaphor; symbol; Solomon’s temple; ecclesiology
Available at various institutes of the ASCR
On jest figura neb obraz kostela a chrámu duchovního, jenž je tělo naše. Chrám jako metafora
Příspěvek se zabývá zejména literárními metaforizacemi křesťanského chrámu ve třech základních typologiích chrámu, a to jako metafory lidského těla, prefigurativního vzoru dějin Šalomounova chrámu ...
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