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Diffraction and luminescence analysis of extremely rapidly cooled molten system(LiF-CaF)-xLnF(Ln=Sm and Gd)

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Transactions of Nonferrous Metals Society of China 2021年第4期31卷 1151-1164页

作者： miroslav BOČA Jarmila MLYNÁRIKOVÁ Iveta MACKOVÁ Dušan JANIČKOVIČ Adriana CZÍMEROVÁ Zhong-ning SHI Institute of Inorganic Chemistry Slovak Academy of SciencesDúbravskácesta 9SK-84536 BratislavaSlovakia Institute of Physics Slovak Academy of SciencesDúbravskácesta 9SK-84511 BratislavaSlovak School of Metallurgy Northeastern UniversityShenyang 110819China

Samples of(LiF-CaF2)eut-x SmF3(-x GdF3)(x=0.03-0.50) were prepared by spontaneous cooling as well by very fast cooling(using the rapid solidification processing(RSP) method) which provide two types of sample morphology: riffle-like and sphere-like fragments. All types of samples were studied by XRD, optical absorption and fluorescence spectroscopy. The presence of LiF stabilises the cubic cell dimension, and the content of lanthanide fluorides presents influence on phases formed, as well as the crystallinity of the system, in both the spontaneously and rapidly-cooled systems. The photoluminescence properties of the investigated systems are dependent on the lanthanide fluoride content. The intensity of the emission bands, corresponding to the Sm3+ ion, reaches the maximum when the Sm content is x(SmF3)=0.03. An even stronger dependence is observed of optical properties on the morphology of the samples, i.e. whether the samples are spontaneously cooled or processed by the RSP method followed by mechanical grinding. Mechanical grinding enhances the luminescent properties and leads to higher emission intensities. It is also shown that the photoluminescent spectroscopy is suitable for detection/approval of lowered local symmetry via significant splitting of spectral bands.

关键词： molten salts rapidly cooled molten system SmF3 GdF3 absorption spectra fluorescence spectra luminescence properties

Heat Transfer during Spray Cooling of Flat Surfaces with Water at Large Reynolds Numbers

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Journal of Flow Control, Measurement & Visualization 2016年第3期4卷 104-113页

作者： Milan Hnizdil Martin Chabicovsky miroslav Raudensky Tae-Woo Lee Laboratory of Heat Transfer and Fluid Flow Brno University of Technology Brno Czech Republic Mechanical and Aerospace Engineering SEMTE Arizona State University Tempe AZ USA

We present a new Nusselt number correlation for spray cooling at large Reynolds numbers and high surface temperatures for water sprays impinging perpendicularly onto a flat plate. A large set of experimental data on spray cooling of hot surfaces with water has been analyzed, including the water temperature effects. For large-scale cooling, such as in industrial processes, large number of injection parameters such as number, type, pressure, and angle of the spray injection has led to a multitude of correlations that are difficult for general and practical applications. However, by synthesizing a set of experimental data where all of the above parameters have been varied, we find that the Nusselt number and therefore the heat transfer coefficient can be cast accurately as a function of the Reynolds number. Water is widely used as the coolant during spray cooling, and has a specific phase change characteristic. At large Reynolds number (Re > 100,000) and surface temperature (Ts > 600°C) ranges, which are of interest in large-scale spray cooling, the effect of water temperature is quite significant as it affects the film boiling close to the surface. This effect also has been parameterized using experimental data.

关键词： Impinging Flow Spray Cooling Heat Transfer Measurements

The Influence of Modulated Slotted Synthetic Jet on the Bypass of Hump

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Journal of Mechanics Engineering and Automation 2014年第3期4卷 225-233页

作者： Petr Pick miroslav Andrle Vladislav Saila Milan Matej ka Department of Fluid Mechanics and Thermodynamics Faculty of Mechanical Engineering at CTU in Prague Prague 12112 CzechRepublic

This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used： the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA （constant temperature anemometry） probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.

关键词： Synthetic jet Kiel probe CTA probe loss coefficient phase shift modulation.

A Contribution to Analysis of Collapse of High-Rise Building Inspired by the Collapses of WTC1 and WTC2: Derivation of Simple Formulas for Collapse Upper Speed and Acceleration

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Journal of Applied Mathematics and Physics 2018年第12期6卷 2666-2680页

作者： Ivan Nemec miroslav Trcala JiríVala Adéla Vanecková Faculty of Civil Engineering Brno University of TechnologyBrnoCzech Republic FEM Consulting BrnoCzech Republic

The paper is a contribution to the technical discussion concerning the collapses of the WTC buildings. It returns to the problem of the dynamics of the collapses;it does not concern the reason why the buildings started collapsing, but investigates the dynamics of the collapse itself. It works with the same assumptions as the official NIST report [1], i.e. that the falling mass hits the motionless mass beneath;the supporting columns loose stability and the mass of the pertinent floor starts to fall together with the falling mass. The aim was to derive the theoretical upper limit of the speed of the collapse, supposing that influence of the columns which resist the fall, is neglected. The differential equation of the fall was obtained using two independent laws of mechanics, with the identical result. Its solution can be found from a very simple explicit formula. The theoretical upper limit acceleration of the fall obtained by such formula is one third of the gravitational acceleration, which is faster than it was observed in the case of the collapses of WTC1 and WTC2. This leads to the conclusion that the mechanism of the collapse must be different from the assumed and the falling mass must not hit the motionless mass bellow it, but rather a mass which had started to fall before the impact of the falling mass occurred.

关键词： Progressive Collapse WTC High-Rise Building Equation of Motion Upper Limit Acceleration 9/11

Sustaining forest biodiversity:Exploring the effect of long-term natural disturbance dynamics on contemporary lichen communities in primary forest ecosystems

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Forest Ecosystems 2024年第4期11卷 556-567页

作者： Rhiannon Gloor Marek Svitok Martin Mikolas Jenyk Hofmeister Josef Halda Pavel Janda Francesco Maria Sabatini Lucie Zemanova Arne Buechling Daniel Kozak Matej Ferencik Michal Frankovic Martin Dusatko miroslav Svoboda Department of Forest Ecology Faculty of Forestry and Wood SciencesCzech University of Life Sciences PragueKamycka 129Praha 6–Suchdol16500Czech Republic Faculty of Ecology and Environmental Sciences Technical University in ZvolenT.G.Masaryka 2496001ZvolenSlovakia Institute of Botany Plant Science and Biodiversity CenterSlovak Academy of SciencesDúbravska cesta 984523BratislavaSlovakia PRALES Odtrnovie 56301322RosinaSlovakia Faculty of Science University of Hradec KraloveHradecka 1285Hradec KraloveⅢ50003Czech Republic BIOME–Biogeography and Macroecology Department of BiologicalGeological and Environmental Sciences(BIGEA)Alma Mater Studiorum-University of Bolognavia Irnerio 42BolognaItaly

In this era of biodiversity loss and climate change,quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation *** and epixylic lichens are effective forest quality bioindicators,as they are generally long-lived organisms supported by continuity of specific forest structures and their associated microclimatic ***,how lichen communities respond to the effects of fluctuating historical disturbances remains *** a dendrochronological approach,this study investigates how natural disturbance dynamics indirectly influence various lichen community metrics in some of Europe's best-preserved primary mixed-beech *** modelling revealed that natural historical disturbance processes have decades-long effects on forest structural attributes,which had both congruent and divergent impacts on lichen community richness and *** species richness indirectly benefited from both historical and recent higher-severity disturbances via increased standing dead tree basal area and canopy openness respectively-likely through the presence of both pioneer and late-successional species associated with these ***-listed species richness showed a dependence on habitat continuity(old trees),and increased with disturbance-related structures(standing dead trees)whilst simultaneously benefiting from periods without severe disturbance events(old trees and reduced deadwood volume).However,if the disturbance occurred over a century in the past,no substantial effect on forest structure was ***,while disturbance-mediated forest structures can promote overall richness,threatened species appear vulnerable to more severe disturbance events-a concern,as disturbances are predicted to intensify with climate ***,the high number of threatened species found reinforce the critical role of primary forest structural attributes for biodiversity ***

关键词： Mixed-beech forests Species richness Old-growth forests Carpathian mountains Biodiversity conservation Dendroecology Fagus sylvatica

Femoral notch cleaning in anterior cruciate ligament reconstruction: a new instrument

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Journal of Biomedical Science and Engineering 2010年第4期3卷 359-360页

作者： miroslav Z. Milankov Natasa Miljkovic Zoran Gojkovic 不详

This article describes using of this new, improvised instrument that enables better removal of ACL remnants, increased visibility of the intercondylar notch, precise location of the femoral tunnel and by doing this shor- tens the operative time. Also, the use of this instrument is cost beneficial, because it decreases the number of disposable shaver tips used and can decrease the cost of the procedure which is important for countries with poor economies.

关键词： Anterior Cruciate Reconstruction Femoral Notch Cleaning Improvised Instrument

Faraday effect measurements of holmium oxide(Ho2O3) ceramics-based magneto-optical materials

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High Power Laser Science and Engineering 2018年第1期6卷 7-12页

作者： David Vojna Ryo Yasuhara Hiroaki Furuse Ondrej Slezak Simon Hutchinson Antonio Lucianetti Tomas Mocek miroslav Cech Hi LASE Centre Institute of Physics Czech Academy of Sciences Za Radnici 828 Dolni Brezany 252 41 Czech Republic National Institute for Fusion Science National Institutes of Natural Sciences 322-6 Oroshi-cho Toki Gifu 509-5292 Japan Kitami Institute of Technology 165 Koen-cho Kitami Hokkaido Japan Department of Physical Electronics Faculty of Nuclear Sciences and Physical Engineering Czech Technical University in PragueBrehova 7 Prague 115 19 Czech Republic

Faraday effect measurements of holmium oxide(Ho_2O_3) ceramics-based magneto-optical materials, highly potential material candidates for high-energy laser Faraday isolators, are presented in this paper. Temperature dependence of the Verdet constant of nondoped Ho_2O_3 ceramics was measured for temperatures 15–305 K at 1.064 μm *** Verdet constant dispersion for wavelengths 0.5–1 μm and 1.064 μm was measured for both nondoped Ho_2O_3 ceramics and Ho_2O_3 ceramics doped with terbium Tb3+(0.2 at. %) and cerium Ce3+(0.1 at. %) ions. The results suggest that the relatively low level of doping of Ho_2O_3 with these ions has no significant boosting impact on the Faraday effect. Therefore, other compositions of Ho_2O_3 ceramics-based magneto-optical materials, as well as various doping concentrations, should be further examined.

关键词： Faraday effect magneto-optics optical materials

Effect of the directional crystallization onmicrostructure of Ti46Al-5Nb-1W

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广东有色金属学报 2005年第2期15卷 289-293页

作者： Vitezslav Smishek miroslav Kursa G.S.Burkhanov VSB-Technical University of Ostrava Ostrava-Poruba Czech republic Baikov Institute of Metallurgy and Materials Science Russian Academy of Sciences Moscow119991 Russia

Ti-Al based intermetallic alloys are promising for various applications in aerospace and automobile industry. Their favorable properties, such as low density and good corrosion resistance, are accompanied on the other hand by low toughness and very difficult metallurgy. One of the possibilities to improve the toughness of Ti-46Al-5Nb-1W (%, at. fraction) alloy consists in change of their microstructure into lamellar microstructure, which can be reached moreover by directional crystallization. This experiment is described in this paper. Samples of the Ti-46Al-5Nb-1W (%, at. fraction) alloy prepared by plasma and vacuum-induction metallurgy were subjected to directional crystallization. Cooling rates were constant and ranged from 5.56 × 10-6 m/s to 1.18 × 10 -4 m/s. Directional crystallization has been accomplished in ceramic tubes made of corundum-Al2O3. The samples were studied by metallographic and chemical *** microstructure of the samples was found to consist of α2- and γ-phase lamellas. Moreover, ceramic particles Al2O3 were found to be present in the samples. Distribution of the alloying elements in the samples was homogenous.

关键词：钛铝合金机械性能韧性显微结构

Effect of Forging Ratio on Microstructure of the of the 1.5710 Grade Steel

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Journal of Mechanics Engineering and Automation 2015年第8期5卷 454-458页

作者： Greger miroslav Michal Madaj Petrzela Jiri Laszlo Vladimir Department of Materials Forming Faculty of Metallurgy and Materials Engineering VSB--Technical University of OstravaOstrava 70833 Czech Republic Regional Materials Science and Technology Centre Faculty of Metallurgy and Materials Engineering VSB--Technical Universityof Ostrava Ostrava 70833 Czech Republic ViTKOVICE HEAVY MACHINERY a.s. Ostrava 70300 Czech Republic

Intensity of structural changes during forging is usually determined in dependence on the forging ratio. Forging ratio at elongation is most often calculated with use of simple relations, which are based on the change of cross section of the forged pieces. The intensity of structure development is influenced not only by the simple change of cross sections, but also by relative length of the stroke, magnitude of deformation in individual passes, manner of edging, temperature, friction and shape of anvils. The paper gives an analysis of influence of the relative length of the stroke on the forging ratio.

关键词： Forging relative length of the stroke forging ratio.