342 research outputs found
Fire resistance of reinforced concrete and steel structures
No full textThe scientific bases of ensuring fire resistance of reinforced concrete and steel building structures in the conditions of modern extreme influences are laid.
The current state of fire safety of buildings and structures, as well as approaches, methods and tools for its assessment are analyzed. Analysis of emergencies and fires in the world has shown that the vast majority of them occur in buildings and structures. It is shown that the cause of catastrophic consequences and destruction is the non-compliance of the actual limit of fire resistance of building structures with regulatory requirements. This is due to the imperfection of methods and means of assessing the fire resistance of building structures, including fire-retardant.
To overcome the shortcomings identified during the analysis, the paper develops physical and mathematical models of thermal processes occurring in the fire-retardant reinforced concrete structure. Based on the proposed models, a computational-experimental method for estimating the fire resistance of such structures has been developed. The efficiency of the proposed method was tested by identifying the relationship between the parameters of the fire-retardant plaster coating “Neospray” and the fire resistance of fire-retardant multi-hollow reinforced concrete floor.
The study of fire resistance of steel structures is proposed to be carried out using reduced samples in the form of steel plates with dimensions of 500×500×5 mm. Based on the proposed models, a calculation and experimental method for estimating the fire resistance of steel structures, as well as an algorithm and procedures for its implementation have been developed. The verification of the efficiency of the proposed method was carried out in the ANSYS software package using the aged coating “Phoenix STS” and the coating “Amotherm Steel Wb” under heating conditions at the temperature of the hydrocarbon fire.
The reliability of the developed models and methods is checked. It is established that random errors in temperature measurement significantly affect the accuracy of determining the thermophysical characteristics and limits of fire resistance. In general, the efficiency of the proposed calculation and experimental methods with sufficient accuracy for engineering calculations is confirmed
"Re-creating" Tadeusz Konwicki’s fiction : "Little apocalypse" and Yurii Andrukhovych’s "Moscoviad"a
No full textOn the basis of a comparative analysis of the worlds presented in Moscoviada by Yurii Andrukhovych and in the Little Apocalypse by Tadeusz Konwicki the article demonstrates the meaning of "metaphorical translation". Using the category proposed by Joseph Brodsky, the author of the article shows how similar characters, who search for their identities, are presented in both books
Growth of nanoparticles in liquid medium using magnetron sputtering technique
No full textTitle: Growth of nanoparticles in liquid medium using magnetron sputtering technique Author: Josef Kučera Department: Department of Surface and Plasma Science Supervisor: Mgr. Yurii Yakovlev, Ph.D., Department of Surface and Plasma Science Abstract: This thesis investigates the preparation of platinum and platinum-ruthenium alloy nanoparticles using magnetron sputtering method on a liquid substrate. Polypropylene glycol with three different molecular weights of 425, 1000, and 4000 was chosen as the liquid substrate. The influence of the different viscosities of these substrates on the size and morphology of the nanoparticles produced in the magnetron was investigated. Dynamic light scattering and transmission electron microscopy methods were used to determine the size of the nanoparticles. Furthermore, the catalytic activity of the produced nanoparticles in an alkaline environment was investigated using the rotating disk electrode technique. Keywords: Nanoparticles, Magnetron Sputtering, Polypropylene glycol, Hydrogen Fuel Cells, Water Electrolyzers, Hydrogen oxidation/reduction reactions
George Yurii Shevelov as a master of academic writing
No full textУкраїнськомовні лінгвістичні праці Юрія Шевельова свідчать про нього як про яскраву авторську індивідуальність. У статті проаналізовано стильові та художні засоби, якими він послуговується, щоб дієвіше впливати на читачів. Зроблено висновок про актуальність його мовної практики для вдосконалення й уточнення сучасних норм українського наукового стилю.Ukrainian linguistic papers by George Yurii Shevelov are evidence of his outstanding author individuality. The article deals with analysis of some stylistic and expressive means, which he uses for more effective influence upon his readers. The conclusion of the study reveals that his language practice is topical for development and improvement of modern standards of Ukrainian academic discourse
George Yurii Shevelov as a master of academic writing
No full textУкраїнськомовні лінгвістичні праці Юрія Шевельова свідчать про нього як про яскраву авторську індивідуальність. У статті проаналізовано стильові та художні засоби, якими він послуговується, щоб дієвіше впливати на читачів. Зроблено висновок про актуальність його мовної практики для вдосконалення й уточнення сучасних норм українського наукового стилю.Ukrainian linguistic papers by George Yurii Shevelov are evidence of his outstanding author individuality. The article deals with analysis of some stylistic and expressive means, which he uses for more effective influence upon his readers. The conclusion of the study reveals that his language practice is topical for development and improvement of modern standards of Ukrainian academic discourse
Hot Torsion Tests of AA6082 Alloy
No full textMaterials characterization and the knowledge of their elastic-plastic behavior are of fundamental importance for the design of industrial manufacturing processes. Nowadays, FEM simulation is the main tool used to optimize product quality and minimize scraps, and the numerical codes have evolved over the years to obtain accurate solutions with reduced computational times. Nevertheless, in order to perform reliable simulations, it is necessary to include accurate modeling of the material flow stress. Hot torsion is a powerful method for the characterization of the material flow stress because, tests can be carried out at constant speeds and temperatures, reaching large strain values, and thus getting over the limits of compression and tensile tests. In this paper the hot torsion characterization applied to AA6082 alloy is presented: tests were performed with equivalent strain rates of 0.01, 0.1, 1, and 10 s-1, in the temperature range from 440 to 550 °C (from 713.15 to 823.15 K). The results are presented in terms of equivalent stress vs equivalent strain. Finally, the material flow stress curve was predicted by the Hyperbolic sine model and Hensel-Spittel law, and the material parameters A, m1-9 are provided for the temperature expressed in °C and K
Growth of nanoparticles in liquid medium using magnetron sputtering technique
No full textNázev práce: Růst nanočástic v kapalném prostředí technikou magnetronového naprašování Autor: Josef Kučera Katedra / Ústav: Katedra fyziky povrchů a plazmatu Vedoucí bakalářské práce: Mgr. Yurii Yakovlev, Ph.D., Katedra fyziky povrchů a plazmatu Abstrakt: Tato práce zkoumá přípravu nanočástic platiny a platino-rutheniové slitiny pomocí metody magnetronového naprašování na kapalný substrát. Jako použitý kapalný substrát byl zvolen polypropylenglykol se třemi různými molekulárními hmotnostmi 425, 1000 a 4000. U těchto substrátů bylo prozkoumáno, jak jejich rozdílná viskosita ovlivňuje velikost a morfologii nanočástic připravených v magnetronu. Pro určení velikosti nanočástic byly využity metody dynamického rozptylu světla a transmisní elektronové mikroskopie. Dále byla prozkoumána katalytická aktivita vytvořených nanočástic v alkalickém prostředí pomocí techniky rotační diskové elektrody. Klíčová slova: Nanočástice, magnetronové naprašování, polypropylenglykol, vodíkové palivové články, elektrolyzéry vody, vodíkové redoxní reakce.Title: Growth of nanoparticles in liquid medium using magnetron sputtering technique Author: Josef Kučera Department: Department of Surface and Plasma Science Supervisor: Mgr. Yurii Yakovlev, Ph.D., Department of Surface and Plasma Science Abstract: This thesis investigates the preparation of platinum and platinum-ruthenium alloy nanoparticles using magnetron sputtering method on a liquid substrate. Polypropylene glycol with three different molecular weights of 425, 1000, and 4000 was chosen as the liquid substrate. The influence of the different viscosities of these substrates on the size and morphology of the nanoparticles produced in the magnetron was investigated. Dynamic light scattering and transmission electron microscopy methods were used to determine the size of the nanoparticles. Furthermore, the catalytic activity of the produced nanoparticles in an alkaline environment was investigated using the rotating disk electrode technique. Keywords: Nanoparticles, Magnetron Sputtering, Polypropylene glycol, Hydrogen Fuel Cells, Water Electrolyzers, Hydrogen oxidation/reduction reactions.Department of Surface and Plasma ScienceKatedra fyziky povrchů a plazmatuMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Optimalizace svazků palivových článků pomocí ultrazvukového zvlhčovače.
No full textTitle: Optimization of the Performance of Fuel Cell Stacks Using an Ultrasonic Humidi- fier. Author: Martin Vaněk Department: Department of Surface and Plasma Science Supervisor: Mgr. Yurii Yakovlev, Ph.D., Department of Surface and Plasma Science Abstract: This work is concerned with the optimization of the performance of PEM hydrogen fuel cell stacks, a technology that opens up new possibilities for clean energy storage and restoration. We have hand-built a PEMFC open-cathode stack of 20 cells and measured its basic characteristics such as the j-V and j-P curves as well as the dependency of the temperature of the stack on power produced by the stack for constant power of the cooling fans. We have implemented and tested the performance of a new method for water and thermal management - the humidification of air via the use of an ultrasonic water fog generator. Several tests - measuring cooling efficiency, voltage variations between different cells, and j-V and j-P curves - were performed under different temperatures and with or without humidification. Keywords: fuel cell, self humidification, open cathode, performance 1Název práce: Optimalizace svazků palivových článků pomocí ultrazvukového zvlhčovače. Autor: Martin Vaněk Katedra: Katedra fyziky povrchů a plazmatu Vedoucí bakalářské práce: Mgr. Yurii Yakovlev, Ph.D., Katedra fyziky povrchů a plaz- matu Abstrakt: Tato práce se zabývá optimalizací výkonu svazků PEM palivových článků, technologie, která otevírá nové možnosti pro uskladnění a zpětnou výrobu elektrické energie. Sestavili jsme dvaceticelový sériový svazek PEM vodíkových palivových článků s otevřenou katodou a změřili jeho základní charakteristiky, jako jsou j-V a j-P křivky a také závislost teploty článku na výkonu, který produkuje za konstantního výkonu chladících větráků. Implementovali a otestovali jsme novou metodu pro správu vody a teploty článku - zvlhčování příchozího vzduchu pomocí ultrazvukového generátoru mlhy - a její vliv na výkon svazku. Provedli jsme několik testů - měření efektivity chlazení, variací v napětích na jednotlivých celách a j-V a j-V křivky - a to za různých podmínek, konkrétně při různých teplotách a se zvlhčováním či bez něj. Klíčová slova: palivový článek, samozvlhčování, otevřená katoda, výkon 1Department of Surface and Plasma ScienceKatedra fyziky povrchů a plazmatuMatematicko-fyzikální fakultaFaculty of Mathematics and Physic
Ukrainian Children’s Folk Clothing in the Artistic and Ethnographic Heritage of Yurii Pavlovych
No full textУ розвідці розглядається питання дитячого народного вбрання українців у доробку видатного українського етнолога Юрія Павловича (1872–1947). Його багата спадщина, що налічує тисячі замальовок українського народного побуту, вбрання, житла та краєвидів, досліджена й представлена у праці «Україна в типажах народних, краєвидах і архітектурі: художньо-етнографічна спадщина Юрія Павловича», що була видана в Інституті мистецтвознавства, фольклористики та етнології ім. М. Т. Рильського АН України (ІМФЕ ім. М. Т. Рильського) у 2010 році. Упродовж 1921–1934 років Ю. Павлович був постійним позаштатним співробітником Кабінету антропології та етнології ім. Хв. Вовка, збагачуючи напрацювання цієї установи докладним ілюстративним матеріалом. Частина малюнків і праць Ю. Павловича висвітлює питання дитячої одягової культури. Ці матеріали є надзвичайно цінними для вивчення дитячої субкультури, особливостей дитячого вбрання, його форм і специфіки. Прикметним є оригінальний погляд автора ілюстрацій, що фіксував малопомітні та нетипові деталі дитячого повсякдення. Для дослідження було залучено малюнки та рукописи Ю. Павловича з Архівних наукових фондів, рукописів та фонозаписів ІМФЕ ім. М. Т. Рильського (фонди 1 та 39). На основі виявлених замальовок здійснено спробу проаналізувати характерні риси та особливості саме дитячого вбрання, їх інформативне значення для вивчення дитячого народного одягу українців першої половини ХХ ст. Малюнки й матеріали відображають різноманітні аспекти дитячої одягової культури, її варіативність, усталені норми і трансформації як у традиційній, так і міській культурі, а саме в Києві. У виявлених замальовках є змога побачити кольори костюма, естетичний смак, традиції та тенденції у створенні одягу. Зафіксовані Ю. Павловичем типажі, елементи костюма й зовнішній вигляд виразно репрезентують локальну специфіку дитячого вбрання. Унікальні матеріали є цінним джерелом для вивчення народного одягу, а також питань щодо ролі дитини та дитинства в українській культурі.The article examines the issue of children’s folk clothing of Ukrainians in the work of the outstanding Ukrainian ethnologist Yurii Pavlovych (1872–1947). His rich heritage includes thousands of sketches of Ukrainian folk life, clothing, housing, and landscapes, are studied and presented in the work «Ukraine in Folk Types, Landscapes, and Architecture: Artistic and Ethnographic Heritage of Yurii Pavlovych» published by the M.T. Rylskyi Institute of Art Studies, Folkloristics, and Ethnology in 2010. From 1921 to 1934, Yurii Pavlovych worked as a permanent freelance employee of the Cabinet of Anthropology and Ethnology named after Khvedir Vovk, enriching the work of this institution with detailed illustrative material. Some of Yurii Pavlovych’s drawings and works highlight the issues of children’s clothing culture. These materials are extremely valuable for studying the children’s subculture, features of children’s clothing, its forms, and specifics. The original point of view of the author of the illustrations, who fixed the inconspicuous and atypical details of children’s everyday lives, is noteworthy. During the preparation of the research, drawings and manuscripts of Yurii Pavlovych involved from the Archival Scientific Funds of Manuscripts and Audio Recordings of the Maksym Rylskyi Institute of Art Studies, Folkloristics and Ethnology of the National Academy of Sciences of Ukraine (funds 1 and 39). Based on the discovered sketches, an attempt was made to analyse the characteristic features and peculiarities of children’s clothing, their informative value for the study of children’s folk clothing of Ukrainians in the first half of the XX century. Drawings and materials reflect various aspects of children’s clothing culture, its variability, established norms, and transformations in both traditional and urban culture, namely in Kyiv. In the discovered sketches, it is possible to see the colours of the costume, aesthetic taste, traditions, and trends in clothing creation. The types, costume elements, and appearance recorded by Yurii Pavlovych clearly represent the local specificity of children’s clothing. The unique materials are a valuable source for the study of folk dress, as well as questions about the role of the child and childhood in Ukrainian culture. Some of Yurii Pavlovych’s drawings are being published for the first time
Optimization of the performance of fuel cell stacks using an ultrasonic humidifier.
No full textTitle: Optimization of the Performance of Fuel Cell Stacks Using an Ultrasonic Humidi- fier. Author: Martin Vaněk Department: Department of Surface and Plasma Science Supervisor: Mgr. Yurii Yakovlev, Ph.D., Department of Surface and Plasma Science Abstract: This work is concerned with the optimization of the performance of PEM hydrogen fuel cell stacks, a technology that opens up new possibilities for clean energy storage and restoration. We have hand-built a PEMFC open-cathode stack of 20 cells and measured its basic characteristics such as the j-V and j-P curves as well as the dependency of the temperature of the stack on power produced by the stack for constant power of the cooling fans. We have implemented and tested the performance of a new method for water and thermal management - the humidification of air via the use of an ultrasonic water fog generator. Several tests - measuring cooling efficiency, voltage variations between different cells, and j-V and j-P curves - were performed under different temperatures and with or without humidification. Keywords: fuel cell, self humidification, open cathode, performance
- …
