The study of internal structure of woven glass and carbon fiber reinforced composite materials with embedded fiber-optic sensors

In this work, samples from composite materials with embedded optical fibers are investigated. It is known that for unidirectional layered composite materials, under certain conditions, a distortion of the internal structure and the formation of such technological defect as resin pocket in the region of the embedded optical fiber occur. So it is important to evaluate the change in the internal structure for other types of reinforcement, in particular, woven reinforcement. Analysis of the internal structure of the studied materials with 2´2 twill weave style was carried out using a digital microscope. In addition, the reflected optical signal from the Bragg gratings after being embedded into the composite material is analyzed

Empirical research of student leadership’s content parameters

The aim of this article was to perform a retrospective analysis and generalization of the content parameters of student leadership through an empirical study. Sociometric method and psychodiagnostic instruments were used to establish the values of student group leaders. Significant correlations between the studied leadership parameters were found. The sociometric status of student leaders was determined and their values were clarified. The stages and challenges of forming student leadership qualities were outlined. The model of the development of student leadership qualities was graphically constructed and substantiated. It was generalized that the empirical study of the content parameters of student leadership contains significant scientific facts that should be implemented in the educational process; the data can be useful to university administrations and student group curators

The organization training process system for young hockey players through speed qualities development by the means of "Ice track”

The article analyses the data obtained by the sigma sports pulsometer of pc15 with the author's technology realization within the speed endurance development for 10–11-year-old hockey players by means of a specialized hockey track. There is a description of the narrative and final results for each technology (program) stage. Within the stages of the pedagogical experiment, there was a classification test of physical development, which allowed us to speak about the effectiveness of the technology in use

Numerical analysis of the strain values obtained by FBG embedded in a composite material using assumptions about uniaxial stress state of the optical fiber and capillary on the Bragg grating

One of the issues in the strain measurement with the help of fiber-optic sensors based on Bragg gratings is the calculation of the strain based on the information from the sensor and its correspondence to the material strain. Relationships between the data measured by the sensor and the strain in the Bragg grating have a unique solution under the condition of uniaxial stress state of the fiber, which are not fulfilled when the fiber is embedded in the material. The paper presents the results of numerical experiments with an example of a model problem for a polymer composite material with an embedded optical fiber, which can be surrounded by a resin pocket. The presented results allow to estimate the error of the strain values calculated on the basis of uniaxial stress state assumption of the optical fiber. Based on numerical calculations, parameters of a capillary on an optical fiber in the Bragg grating zone are estimated, ensuring uniaxial stress state of the fiber in the Bragg grating zone. To ensure these conditions, the cross section of the capillary in an isotropic material is a circle, and in an anisotropic material, good results can be obtained with an elliptical cross section

The System of Taxation of Individual Entrepreneurs in the New Realities of Industrialization and Digitalization

The topic discussed in this article is current today, since the material contained in it is collected taking into account all the latest amendments to the tax code of the Russian Federation and some federal laws. The article can be a reference material for individual entrepreneurs who are faced with the problem of choosing a tax regime, or for those who want to get acquainted with the latest innovations of the tax code. The nuances of individual entrepreneur taxation in 2020-2021 are considered. Comparative analysis of different tax systems of individual entrepreneur is given, and advantages and disadvantages of each of them are revealed. Examples of calculations of the value of tax or contribution for an individual entrepreneur are give

Optimisation de la production et de l'utilisation des supraconducteurs

Ce travail de thèse est consacré à l'optimisation du processus de fabrication des supraconducteurs à basse température (SBT) et à haute température (SHT). Le but est l'optimisation de fabrication de ces produits.Le premier chapitre est dédié au processus de production des SBT. La recherche concerne le problème de réchauffement de la surface des fils par les forces de friction lors du processus d’étirage. Le processus de réchauffement/refroidissement génère des contraintes résiduelles. Cet aspect a été traité dans ce chapitre. On y présente également une méthode pour déterminer les angles optimaux des outils utilisés dans la fabrication des supraconducteurs.Le deuxième chapitre donne une présentation générale des SHT. On donne d’abord l’historique de ces produits, ensuite les développements en cours et les perspectives. Il présente aussi le processus de fabrication de ce matériel et ses défis. Le chapitre traite en particulier des SHT de deuxième génération et montre l’intérêt de l’emploi de la modélisation numérique.Le troisième chapitre présente un modèle simplifié pour le comportement mécanique des SHT. Ce modèle est basé sur la théorie classique des poutres associée à une discrétisation de la poutre en sous-couches travaillant en traction-compression. Ce modèle prend en compte le comportement plastique des composantes de la poutre SHT. Le modèle a été implémenté dans un environnement MATLAB. La validation du modèle est effectuée par sa confrontation à des analyses par éléments finis. Le modèle est ensuite utilisé pour l'analyse des configurations industrielles dans un but d’optimisation.Le quatrième chapitre présente la vérification numérique du modèle décrit dans le chapitre précédent sur un essai de flexion effectuée en laboratoire sur une bande «poutre» en SHT. La comparaison entre les résultats numériques et les données expérimentales montre le bon fonctionnement du modèle développé.This thesis is devoted to the optimization the process of production of low-temperature superconductor (LTS) as well as high-temperature superconductor (HTS) products. The aim of the work is the optimization of the fabrication process. Chapter 1 deals with the process of production of low-temperature superconductors. It provides analysis of the heating/cooling phenomena in the fabrication process. The chapter also proposes a method for determining the optimum angles of tools used in the fabrication of low-temperature superconductor. Chapter 2 provides a general presentation of the high-temperature superconductors (HTS). The history of development of this material is summarized. The chapter gives a particular focus on the 2nd Generation of HTS. After a presentation of the structure of the high-temperature superconductor, the fabrication process and the challenges, we present the need for the use of numerical model on the design and fabrication of HTS.Chapter 3 presents a simplified model for HTS beams. This model is based on the classical beam theory together with the discretization of each layer in small sub-layers working under purely axial stresses. The model takes into consideration the plastic behavior of the HTS constitutive materials. This model was implemented using MATLAB software. It presents also the validation of this model by its confrontation to finite element analyses as well as its use in the optimal design of HTS. Chapter 4 presents the verification of the numerical model presented in the previous chapter for high-temperature multilayer 2G. The verification is carried out on a bending beam test conducted on a high-temperature superconductor tape. The test was presented first. The comparison of the numerical and experimental results allows the validation of the simplified model on experimental tests

Synthesis and Properties of Thin Film Nanocomposites Sn-Y-O for Gas Sensors

Three-component thin film nanocomposites Sn-Y-O were prepared by RF reactive ion-beam sputtering of metal target in the ambient of Ar+O2. Amorphous films were thermal treated at 400 oC for crystallization and stabilization of electrical properties. Atomic composition and morphology of thin films were investigated by X-ray microanalyzer, high-resolution transmission electron microscopy method, atomic force microscopy. It was determined that the presence of Y2O3 additive in composites on the base of SnO2 prevents the growth of big grains up to 3 nm, and can be used for the control of thin film structure. Electrical properties and gas sensitivity of nanocomposite samples were studied and the correlation between grain size and gas sensitive parameters was found

Measurement of Gradient Strain Fields with Fiber-Optic Sensors

The results of measuring gradient strain fields by embedded or mounted point fiber-optic sensors based on Bragg gratings and distributed fiber-optic sensors based on Rayleigh scattering are discussed. Along with the experiment, the results of numerical modeling of strain measurement errors associated with the assumption of uniaxial stress state in the area of the embedded Bragg grating and measurement errors by distributed fiber-optic sensors associated with gage length are presented. Experimental results are presented for 3D printed samples and samples made of polymer composite material. The geometry of the samples was chosen based on the results of numerical simulations, and provides different variants of non-uniform strain distribution under uniaxial tension, including the variant in which the derivative of the strain distribution function changes its sign. A good agreement of numerical results and experimental data obtained by distributed and point fiber-optic sensors in areas where the derivative of the strain distribution function keeps a sign and an increase in the error of strain measurement results by distributed fiber-optic sensors in areas where this derivative changes sign are demonstrated

Dissolved and Suspended Forms of Metals and Metalloids in Snow Cover of Megacity: Partitioning and Deposition Rates in Western Moscow

Concentrations and ratio of dissolved and suspended forms of metals and metalloids (MMs) in snow cover and their deposition rates from the atmosphere in the western part of Moscow were studied. Forms of MMs were separated using a filter with pore diameter of 0.45 μm; their concentrations were measured by ICP-MS and ICP-AES methods. Anthropogenic impact in Moscow caused a significant increase in dust load (2–7 times), concentration of solid particles in snow cover (2–5 times), and mineralization of snow meltwater (5–18 times) compared to the background level. Urban snow contains Sn, Ti, Bi, Al, W, Fe, Pb, V, Cr, Rb, Mo, Mn, As, Co, Cu, Ba, Sb, Mg mainly in suspended form, and Ca and Na in dissolved form. The role of suspended MMs in the city significantly increases compared to the background region due to high dust load, usage of de-icing salts, and the change of acidic background conditions to alkaline ones. Anthropogenic emissions are the main sources of suspended Ca, W, Co, V, Sr, Ti, Mg, Na, Mo, Zn, Fe, Sb, and Cu in the snow cover of traffic zone. These elements’ concentrations in roadside snow cover exceed the background values more than 25 times. The highest concentrations and deposition rates of MMs in the snow of Moscow are localized near the large and medium roads