No (11866)
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11866
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Stereolithography for manufacturing of advanced porous solids
Drechslerová, V.; Neuhäuserová, M.; Falta, J.; Šleichrt, J.; Kytýř, Daniel
2023 - English
The aim of this paper is focused on benefits of stereolithography (SLA) technology for the fabrication of the lightweight lattice structures with potential for load-bearing function and high absorption of impact energy. SLA is an additive manufacturing technology employing the principle of liquid resins curing moderated by radiation of a wavelength from ultra-violet band where resulting material parameters are tunable by setting of the curing process. The batches of samples manufactured using three different resins were subjected to quasi-static uni-axial tensile and compression tests. Acquired data were processed to derive deformation behaviour expressed as stress-strain diagrams and fundamental material properties. Based on the knowledge obtained from the mechanical tests, the setup of the fabrication parameters, the most suitable resin for manufacturing of the lattice structures and the overall suitability of SLA technology for the fabrication of advanced porous materials, were determined.
Keywords:
stereolithography; advanced porous materials; quasi-static testing; resin; mechanical characteristics
Available at various institutes of the ASCR
Stereolithography for manufacturing of advanced porous solids
The aim of this paper is focused on benefits of stereolithography (SLA) technology for the fabrication of the lightweight lattice structures with potential for load-bearing function and high ...
Caves in Bohemia et Moravia Subterranea by Mauritius Vogt (1669–1730)
Rychnová, L.; Vokurka, Michal
2023 - English
The Manuscript Bohemia et Moravia Subterranea (1729) by Mauritius Vogt reflects the subterranean landscapes and underground spaces based on Athanasius Kircher’s theories. The paper analyses the application of Kirchers’s terminology to the natural phenomena from Bohemia and Moravia. Further, we focused on how Vogt worked with his sources – how far he relied on literature, correspondence, or personal experience.
Keywords:
Mauritius Vogt; caves; subterranean; underground; early modern period
Available at various institutes of the ASCR
Caves in Bohemia et Moravia Subterranea by Mauritius Vogt (1669–1730)
The Manuscript Bohemia et Moravia Subterranea (1729) by Mauritius Vogt reflects the subterranean landscapes and underground spaces based on Athanasius Kircher’s theories. The paper analyses the ...
A new blade cascade for flutter studies
Šnábl, Pavel; Pešek, Luděk; Procházka, Pavel P.; Skála, V.
2023 - English
In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major construction improvements over the original cascade which now allow more precise and reliable measurements. The stability of the new blade cascade with five NACA 0010 profiles with rotational degree of freedom is assessed by Travelling Wave Mode approach and Aerodynamic Influence Coefficient approach.
Keywords:
blade cascade; stability; travelling wave mode; aerodynamic influence coefficient
Available at various institutes of the ASCR
A new blade cascade for flutter studies
In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major ...
Novel embedding resins for 3D-SEM II
Šlouf, Miroslav; Pavlova, Ewa; Strachota, Beata; Strachota, Adam; Nebesářová, Jana; Týč, Jiří; Krzyžánek, Vladislav; Skoupý, Radim
2023 - English
Research report for Thermo Fisher Scientific s. r. o., based on common project awarded by TA CR (program: National center of competence, TN01000008).
Keywords:
novel embedding resins; 3D-SEM microscopy; higher e-beam resistance
Available at various institutes of the ASCR
Novel embedding resins for 3D-SEM II
Research report for Thermo Fisher Scientific s. r. o., based on common project awarded by TA CR (program: National center of competence, TN01000008).
An Enzymatic Biosensor with Amperometric Detection in a Flow Injection Analysis for the Determination of L-lactic Acid: Development and Application
Tvorynska, Sofiia; Barek, J.; Josypčuk, Bohdan
2023 - English
An amperometric biosensor consisting of an enzymatic mini-reactor (lactate oxidase covalently\nattached to −NH2 functionalized mesoporous silica powder SBA−15 using glutaraldehyde) and\na silver amalgam-based screen-printed electrode acting as a transducer was developed for the\ndetermination of L-lactic acid (LA) in FIA. The detection potential of −0.9 V vs. Ag pseudoreference\nelectrode was applied for cathodic detection of enzymatically consumed oxygen.\nUnder the optimized conditions, the constructed biosensor enabled selective determination of\nLA with a micromolar limit of detection. Importantly, the proposed biosensor represented\nexcellent operational stability after ≥350 measurements. Finally, it was successfully applied to\nreal sample analysis.
Keywords:
L-lactic acid; Lactate oxidase; Amperometric biosensor; silver amalgam
Available on request at various institutes of the ASCR
An Enzymatic Biosensor with Amperometric Detection in a Flow Injection Analysis for the Determination of L-lactic Acid: Development and Application
An amperometric biosensor consisting of an enzymatic mini-reactor (lactate oxidase covalently\nattached to −NH2 functionalized mesoporous silica powder SBA−15 using glutaraldehyde) and\na silver ...
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 ...
Aerodynamic Measurements on Subsonic Compressor Blade Cascades KR-D-7 and KR-D-8
Šimurda, David; Hála, Jindřich; Luxa, Martin; Radnic, Tomáš
2023 - English
This report contains results and evaluation of aerodynamic measurements conducted on two variant subsonic compressor blade cascades with MCA profile (KR-D-7) and DCA profile (KR-D-8) at transonic flow regimes.
Keywords:
compressor blade cascade; experiment; transonic flow; subsonic flow; MCA profile; DCA profile
Available at various institutes of the ASCR
Aerodynamic Measurements on Subsonic Compressor Blade Cascades KR-D-7 and KR-D-8
This report contains results and evaluation of aerodynamic measurements conducted on two variant subsonic compressor blade cascades with MCA profile (KR-D-7) and DCA profile (KR-D-8) at transonic flow ...
Aerodynamic Measurements on Transonic Compressor Blade Cascades KR-D-9 and KR-D-10
Šimurda, David; Hála, Jindřich; Luxa, Martin
2023 - English
This report contains results and evaluation of aerodynamic measurements conducted on two variant transonic compressor blade cascades with MCA profile (KR-D-10) and DCA profile (KR-D-9) at transonic flow regimes.
Keywords:
compressor blade cascade; experiment; transonic flow; MCA profile; DCA profile
Available at various institutes of the ASCR
Aerodynamic Measurements on Transonic Compressor Blade Cascades KR-D-9 and KR-D-10
This report contains results and evaluation of aerodynamic measurements conducted on two variant transonic compressor blade cascades with MCA profile (KR-D-10) and DCA profile (KR-D-9) at transonic ...
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 ...
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