1,721,022 research outputs found
Mechanical and electrical properties of concrete modified by carbon nanoparticles
No full textThe article presents the study of obtaining electrically conductive concrete using carbon nanoparticles obtained by processing coal in an electric-discharge plasma reactor. An electric-discharge method for producing a sedimentation-resistant and highly dispersed suspension consists in treating coal powder with an electric current in an aqueous medium. Using laser diffraction, it was found that carbon nanoparticles have a particle size in the range from 50 to 500 nm. The microstructure of hardened cement paste was studied using SEM. The compressive strength was tested on cubes with an edge of 100 mm according to EN 12390-6. Determination of the electrical resistance of concrete was carried out on specimens with an edge of 100 mm, placed between two brass plates, through which direct current was passed. The optimum content of carbon nanoparticles (0.01-0.1 % wt.) in the binder is evaluated, which allows to obtain high mechanical properties (30-35 % higher compressive strength compared to a control specimen. It is proved that the mechanism of action of nanoscale modifiers is most manifested in small doses. The dependences of the physicomechanical properties of Portland cement upon the addition of various amounts of carbon nanoparticles are determined. Physicomechanical and exploitation properties of heavyweight electrically conductive concrete are determined. The kinetics of changes in the electrical resistance of concrete at different curing periods is established. © Urkhanova L.A.,Buyantuev S.L.,Urkhanova A.A.,Lkhasaranov S.A.,Ardashova G.R.,Fediuk R.S.,Svintsov A.P., Ivanov I.A., 2019
The dataset about the deformations under axial compression of concrete and cement-sand mortar impregnated with oil
No full textThis article contains data of longitudinal and transverse deformations of concrete and cement-sand prisms impregnated with mineral I-30A, corn and olive oil, under axial compression up to loads that do not create destructive stresses. The stress level, as the ratio of the compressive stress σ to the design compressive strength Rb, varied from 0.054 σ/Rb to 0.845 σ/Rb. The values of deformation for various axial compression loads are presented for control samples and for samples impregnated with mineral oil I-30A with a viscosity of 15 °E, corn oil with a viscosity of 9 °E, and olive oil with a viscosity of 11 °E on Engler scale. The data are associated with the research article “Influence of viscosity of vegetable and mineral oil on deformation properties of concrete and cement-sand mortar” (Alexander et al., 2018). © 2018 The Author
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Water resources as basis for drinking water supply
No full textThe aim of the paper is to analyze the problems of drinking water supply (DWS) in conditions of modern increase of industrial production. The surface and underground resources for DWS are considered and their prospects of further usage are analyzed. A set of measures for ensuring the reliable DWS both for population and industrial enterprises is proposed
МАТЕМАТИЧЕСКОЕ И ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ВОДОРАЗБОРНОЙ АРМАТУРЫ С ПЛОСКИМ ЗАПОРНЫМ ЭЛЕМЕНТОМ
No full textValve-type water fittings, equipped with the flat locking element, work practically without water leaks under operating conditions. A locking element with an orifice-shaped opening in the form of a «curved drop» was designed to improve the regulating capacity of the valve. The results of the studies of the hydraulic characteristics of liquid outflow through the orifices of various shapes carried out by the methods of mathematical simulation and physical experiment were presented in scientific publications by Russian and foreign specialists. Patterns of liquid outflow through the orifice in the form of «curved drop» have not been fully investigated. It constrains the task of designing of the valve-type water fittings with high regulating capacity. A mathematical model has been developed that includes a description of the orifice-shaped opening in the form of a «curved drop» and generates a numerical experiment to determine the hydraulic characteristics of liquid outflow. Within the framework of mathematical and physical experiments, the geometric parameters of an orifice-shaped opening in the form of a «curved drop» were determined, which provide a change in the water flow rate in proportion to its opening. In the process of implementing the physical experiment, the following hydraulic characteristics of the liquid flow through an orifice in the form of a «curved drop» was determined: the local resistance coefficient ζ, the speed ratio φ, the compression ratio ε, the flow coefficient μ, the flow rate of water q at different pressures. It is experimentally determined that the valve head, that equipped with a locking element with an orifice-shaped opening in the form of a "curved drop", is characterized by a high regulating capacity. In the range of the handle rotation from 30° to 180° at a pressure of 0.05 MPa, the water flow rate changes by an average of 1.2 % per 1° of adjustment, and at a pressure of 0.3 MPa - 1.4 % per 1° of adjustment.Водоразборная арматура вентильного типа, оснащенная плоским запорным элементом, в эксплуатационных условиях работает практически без утечек воды. Для повышения регулирующей способности разработан запорный элемент с проходным отверстием в форме «изогнутой капли». Результаты исследований гидравлических характеристик истечения жидкости через отверстия различной формы, выполненных методами математического моделирования и физического эксперимента, представлены в научных публикациях российских и зарубежных специалистов. Однако закономерности истечения жидкости через проходное отверстие в форме «изогнутой капли» исследованы не в полной мере. Это сдерживает решение задач проектирования водоразборной арматуры вентильного типа с высокорегулирующей способностью. Разработана математическая модель, включающая описание проходного отверстия в форме «изогнутой капли» и определяющая численный эксперимент по определению гидравлических характеристик истечения жидкости. В рамках математического и физического экспериментов определены геометрические параметры проходного отверстия в форме «изогнутой капли», обеспечивающие изменение расхода воды пропорционально его открыванию. В процессе реализации физического эксперимента установлены гидравлические характеристики истечения жидкости через отверстие в форме «изогнутой капли»: коэффициент местного сопротивления ζ, коэффициент скорости φ, коэффициент сжатия ε, коэффициент расхода μ, расход воды q при различных давлениях. Экспериментально установлено, что вентильная головка, оснащенная запорным элементом с проходным отверстием в форме «изогнутой капли», характеризуется высокой регулирующей способностью. В диапазоне поворота рукояти от 30° до 180° при давлении 0,05 МПа расход воды изменяется в среднем на 1,2 % на 1° регулирования, а при давлении 0,3 МПа - на 1,4 % на 1° регулирования
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Effect of Petroleum Products on Physical and Mechanical Properties of Concrete and the Reliability of Load-Bearing Structures
No full textPetroleum products, which are widely used in technological processes, fall on concrete and reinforced concrete elements of structures and gradually impregnate them. This can have a negative impact on their reliability and mechanical safety. The influence of oil products with different viscosities on the deformative properties of concrete under axial compression has not been fully studied. Techniques and recommendations for assessing the reliability of concrete and reinforced concrete structures do not take into account changes in their initial deformation properties. This constrains the ability to predict the probability of failure-free operation of load-bearing concrete and reinforced concrete structures in industrial buildings. The aim of the study is to determine the effect of petroleum products with different viscosity (lamp kerosene, industrial oil I-30A, diesel fuel, furnace masut M-40) on the longitudinal and transverse deformation of concrete under axial compression. The study is based on the analysis and generalization of experimental data. It is experimentally established that longitudinal and transverse deformations depend on the viscosity of the impregnated petroleum product and the value of axial compression. Empirical models are developed which enables to calculate the index of mechanical safety as a measure of reliability of bearing concrete and reinforced concrete structures taking into account the operating conditions. The obtained results allow to make scientifically grounded forecast of deformation properties change of bearing concrete and reinforced concrete structures impregnated with oil products and to give quantitative characteristic of their technical condition. Research in this direction is being continued. © 2018, King Fahd University of Petroleum & Minerals
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Water resources as basis for drinking water supply
No full textThe aim of the paper is to analyze the problems of drinking water supply (DWS) in conditions of modern increase of industrial production. The surface and underground resources for DWS are considered and their prospects of further usage are analyzed. A set of measures for ensuring the reliable DWS both for population and industrial enterprises is proposed
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