Propagation of Own Non- Axisymmetric Waves in Viscoelastic Three-Layered Cylindrical Shells

The relevance of the study of the dynamic movements of structures consisting of a thin-walled shell and a viscoelastic cylindrical cavity mounted on it is due to their widespread application in modern technology. The mechanical system under consideration consists of two concentric cylindrical shells with a viscoelastic filler (or cylinder) between the shells. The filler and shell can be firmly attached to the outer and inner shells along the entire cylindrical surface. The basic equations of small oscillations of the shell theory and the three-dimensional viscoelasticity theory are used to describe the oscillations of the “shell-filler-shell” system with the exact satisfaction of the contact boundary. The main purpose of the work is to develop a method and algorithm for calculating the problems of propagation and absorption of natural waves in a mechanical "shell-filler-shell" mechanical system. A calculation method based on Müller, Gauss and orthogonal running methods was developed. The Kirchhoff-Love and Tymoshenko hypotheses are used for the cylindrical shell. For dissipative homogeneous and non-homogeneous mechanical systems, the variation of the real and imaginary parts of the complex phase velocity from different system parameters was studied. For sufficiently long waves, Kirchhoff-Love and Tymoshenko hypothesized that the phase velocities of the first form were found to be well matched. It was also found that it is possible to use shell equations for shortwave, taking into account the compression of the filler. It was found that the increase in filler thickness was particularly significant for the relatively small thickness of the filler

Development of the design of a laboratory vibro-grinding machine for preparing samples for metallographic research

© Published under licence by IOP Publishing Ltd. The article presents the results of testing a prototype vibro-grinding laboratory machine for making samples for metallographic examination. The effectiveness of the method and its suitability for the preparation of thin sections during laboratory studies in the discipline "Material Science" have been established

The method of diagnosing machine systems by measuring the accuracy of manufactured parts

© Published under licence by IOP Publishing Ltd. The main provisions of the technique allowing to create a diagnostic complex of the technical state of the machine system, which is informative at the same time of several diagnostic complexes - geometrical accuracy, strain gauge, technological accuracy, the influence of technological heredity - are revealed

Correction of ted field weakening switching diagram for mainline diesel locomotives of te type

The processes are considered when the stages of weakening of the TED magnetic field are switched on on diesel locomotives of the TE10 type. The analysis of the unstable operation and automatic switching on of the transition relay at partial loads corresponding to the locomotive's speed at the rated load in operation is carried out. TED current algorithms are proposed for correcting the scheme for switching on the relay of transitions from a full field to a weakened field. A variant of the correction circuit is proposed to check its operation during operation. This principle has been violated since the creation of the TE10 diesel locomotive. It is still violated on TE10 diesel locomotives, except for diesel locomotives equipped with the USTA system

Electron irradiation: from test to material tayloring

In this article, we report some examples of how high-energy electron irradiation can be used as a tool for shaping material properties turning the generation of point-defects into an advantage beyond the presumed degradation of the properties. Such an approach is radically different from what often occurs when irradiation is used as a test for radiation hard materials or devices degradation in harsh environments. We illustrate the potential of this emerging technique by results obtained on two families of materials, namely semiconductors and superconductors

Nonequilibrium spin distribution in single-electron transistor

Single-electron transistor with ferromagnetic outer electrodes and nonmagnetic island is studied theoretically. Nonequilibrium electron spin distribution in the island is caused by tunneling current. The dependencies of the magnetoresistance ratio $\delta$ on the bias and gate voltages show the dips which are directly related to the induced separation of Fermi levels for electrons with different spins. Inside a dip $\delta$ can become negative.Comment: 11 pages, 2 eps figure

Formulation of a mathematical problem and methods for solving the development of antistatic clothing for protection from elevated temperatures

The article is devoted to the study and development of a mathematical model of the process of electrification of textile materials in the system "man - clothing - environment" in hot climatic conditions. The phenomenon of static electrification, which occurs in the processes of manufacturing textile materials and products from them, as well as during the operation of finished products, leads to a decrease in the quality of products, causes inconvenience in work, and when an electric discharge occurs, it poses a threat to human life. Such interactions of elements in the "person - clothing - environment" system such as friction, compression, tension, shear increase the contact area of two media, and depending on the rate of these processes, they enhance or weaken metabolic processes, which contributes to an increase in the maximum static charge generated on contacting surfaces. temperature values for special clothing of limited length at the nodal points. At the same time, the number of nodal points is 1601, the number of connected elements is 800. In the area of temperature distribution along the length of the garment, in four different versions, it was found that in the I – version , in the II – version  , in the III – version , in the IV – version , in the V – version , in the VI - version, the length of the clothes in this area increased by 10% compared to the length of the clothes in the II – version

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Влияние кальция на удельную теплоемкость и изменение термодинамических функций алюминиевого проводникового сплава AlTi0.1

Aluminum in terms of electrical conductivity among all known metals ranks fourth after silver, copper and gold. The electrical conductivity of annealed aluminum is approximately 62% IACS of the electrical conductivity of annealed standard copper, which at 20 °C. is taken as 100% IACS. However, due to its low specific gravity, aluminum has a conductivity per unit mass 2 times greater than copper. This property of aluminum gives us an idea of the economic viability of using it as a material for conductors. With equal conductivity (the same length), the aluminum conductor has a cross-sectional area 60% larger than copper, and its mass is only 48% of the mass of copper. In most cases, in electrical engineering, the use of aluminum as a conductor is difficult, and often simply impossible due to its low mechanical strength. An increase in the mechanical strength of aluminum is possible due to the introduction of alloying additives, i.e. creating alloys. In such a case, the mechanical strength increases, causing a noticeable decrease in electrical conductivity. The heat capacity of the aluminum conductor alloy AlTi0.1 (Al + 0.1 wt.% Ti) with calcium in the “cooling” mode was determined from the known heat capacity of the standard aluminum sample. Equations are obtained that describe the cooling rates of specimens made from an aluminum conductor alloy AlTi0.1 with calcium and a reference. Based on the calculated values of the cooling rates of the samples, the equations for the temperature dependence of the heat capacities of the alloys and the standard were formed. The temperature dependences of changes in enthalpy, entropy, and Gibbs energy for the aluminum alloy AlTi0.1 with calcium are calculated by integrating the specific heat capacity. The heat capacity, enthalpy, and entropy of the AlTi0.1 alloy decrease with increasing calcium concentration, and increase with increasing temperature, while the value of the Gibbs energy has an inverse relationship.Среди всех известных металлов, таких как серебро, золото, медь, алюминий по электропроводности занимает четвертое место. Электропроводность меди при 20 °C принимается за 100 % IACS, алюминия в отожженном состоянии она составляет 62 % IACS. Однако, если учесть удельный вес алюминия, то на единицу массы его проводимость в 2 раза больше, чем у меди. Из этого следует, на сколько выгодно применение алюминия в качестве материала для проводников. При одинаковой проводимости (одна и та же длина) проводник из алюминия имеет площадь поперечного сечения на 60 % больше, чем медь. При этом его масса составляет всего 48 % массы меди. Из-за низкой механической прочности в ряде случаев в электротехнике использование в качестве проводника алюминия затруднено или просто невозможно. Легированием другими металлами алюминия можно повысить его механическую прочностью, несмотря на заметное снижение электропроводности. В статье представлены результаты исследования теплоемкости алюминиевого проводникового сплава AlTi0.1 (Al + 0,1 % (мас.) Ti) с кальцием. Исследование проведены в режиме «охлаждения» с использованием в качестве эталона алюминия марки А5N (99,999 % Al). Получены полиномы, описывающие скорости охлаждения образцов из сплавов и эталона. По рассчитанным значениям скоростей охлаждения образцов из исследуемых сплавов сформированы уравнения, описывающие температурную зависимость термодинамических функций (энтальпия, энтропия, энергия Гиббса) сплавов путем интегрирования зависимостей их теплоемкостей. Установлено, что термодинамические функции и теплоемкость сплавов с ростом температуры увеличиваются, а от концентрации кальция уменьшаются.

Коррозия алюминиевого проводникового сплава E-AlMgSi (алдрей), легированного индием

The effect of impurities on the electrical resistance of aluminum is well understood. It is known that the conductivity of aluminum is 65.45 % of the conductivity of copper. The tensile strength of aluminum wires is 150—170 MPa, which, with equal conductivity, is about 65 % of the strength of a copper wire. Such strength of aluminum wires is sufficient to support its own weight and may be insufficient when overloaded with snow, ice or wind.One of the ways to increase the strength of aluminum wires is the use of aluminum alloys having increased strength with a sufficiently high conductivity. One representative of the group of such alloys is the alloy E-AlMgSi (Aldrey). The main hardener of this alloy is the Mg2Si phase, which gives aluminum high mechanical properties.The paper presents the results of a study of the kinetics of high-temperature oxidation and electrochemical corrosion of indium-doped aluminum conductor alloy E-AlMgSi (Aldrey). Using thermogravimetry, it was shown that indium additives and temperature increase the oxidizability of the E-AlMgSi alloy (Aldrey). In this case, the apparent activation energy of the oxidation of alloys decreases from 120.5 to 91.8 kJ/mol. The oxidation rate of alloys determined by the potentiostatic method in a NaCl electrolyte showed that the corrosion resistance of alloys with indium is 20—30 % higher than that of the original alloy. With increasing concentration of NaCl electrolyte in the electrochemical potentials of the alloys decrease, the corrosion rate increases regardless of their composition.Экономическая целесообразность применения алюминия в качестве проводникового материала объясняется благоприятным соотношением его стоимости и стоимости меди. Немаловажным является и то, что стоимость алюминия в течение многих лет практически не меняется.При использовании проводниковых алюминиевых сплавов для изготовления тонкой проволоки, обмоточного провода и т. д. могут возникнуть определенные сложности в связи с их недостаточной прочностью и малым числом перегибов до разрушения. В последние годы разработаны алюминиевые сплавы, которые даже в мягком состоянии обладают прочностными характеристиками, позволяющими использовать их в качестве проводникового материала.Одним из перспективных направлений использования алюминия является электротехническая промышленность. Проводниковые алюминиевые сплавы типа E-AlMgSi (алдрей) являются представителями данной группы сплавов. В работе представлены результаты исследования температурной зависимости теплоемкости, коэффициента теплоотдачи и термодинамических функций алюминиевого сплава E-AlMgSi (алдрей) с висмутом. Исследования проведены в режиме «охлаждения».Показано, что с ростом температуры теплоемкость и термодинамические функции сплава E-AlMgSi (алдрей) с висмутом увеличиваются, а значение энергия Гиббса уменьшается. Добавки висмута до 1 % (мас.) уменьшают теплоемкость, коэффициент теплоотдачи, энтальпию и энтропию исходного сплава и увеличивают энергию Гиббса