Advanced training of modern experts to the perspective direction of development of the domestic education system

The article is about advanced training of modern experts to the perspective direction of development of the domestic education system. It is known that the problem of advanced training of specialists remains as insufficiently studied problemВ статье рассматривается пути, условия реализации опережающего обучения в системе образования, а также формирования у будущих специалистов системных представлений и системного мышлени

Transresonant Evolution of Spherical Waves Governed by the Perturbed Wave Equation

An equation of nonlinear acoustics for radial spherical waves in a solid body has been derived. An approximate solution to this equation is presented, which takes into account nonlinear, spatial, and dissipative effects. It is found that in the transresonant frequency band nonlinear spherical waves may be excited, which it is difficult to classify as the well-known solitonor cnoidal- or shock- or breather-type waves. These resonant spherical waves are also quite different from the well-known sawtooth spherical waves. However, some expressions for the spherical waves resemble the solutions for surface waves.Выводится уравнение нелинейной акустики для радиальных сферических волн в твердом теле. Приближенное решение этого уравнения учитывает нелинейные, пространственные и диссипативные эффекты. Установлено, что в трансрезонансной частотной полосе могут возбуждаться нелинейные сферические волны, которые трудно классифицировать как хорошо известные солитон-, кноидал-, ударные или бриз-тип волны. Эти резонансные сферические волны также существенно отличаются от хорошо известных гладких сферических волн. Однако некоторые выражения для сферических волн напоминают известные решения для поверхностных волн.Виводиться рівняння нелінійної акустики для сферичних хвиль у твердому тілі. Наближений розв’язок цього рівняння ураховує нелінійні, просторові і дисипативні ефекти. Установлено, що у трансрезонансній смузі частот можуть збуджуватися нелінійні сферичні хвилі, які важко класифікувати як добре відомі солитон-, кноїдал-, ударні або бриз-тип хвилі. Ці резонансні сферичні хвилі також суттєво відрізняються від добре відомих гладких сферичних хвиль. Однак деякі вирази для сферичних хвиль нагадують відомі розв’язки для поверхневих хвиль

Electron transport and optical properties of shallow GaAs/InGaAs/GaAs quantum wells with a thin central AlAs barrier

Shallow GaAs/InGaAs/GaAs quantum well structures with and without a three monolayer thick AlAs central barrier have been investigated for different well widths and Si doping levels. The transport parameters are determined by resistivity measurements in the temperature range 4-300 K and magnetotransport in magnetic fields up to 12 T. The (subband) carrier concentrations and mobilities are extracted from the Hall data and Shubnikov-de Haas oscillations. We find that the transport parameters are strongly affected by the insertion of the AlAs central barrier. Photoluminescence spectra, measured at 77 K, show an increase of the transition energies upon insertion of the barrier. The transport and optical data are analyzed with help of self-consistent calculations of the subband structure and envelope wave functions. Insertion of the AlAs central barrier changes the spatial distribution of the electron wave functions and leads to the formation of hybrid states, i.e. states which extend over the InGaAs and the delta-doped layer quantum wells.Comment: 14 pages, pdf fil

Advanced training of specialists: realization ways

The article is about advanced training of modern experts to the perspective direction of development of the domestic education system. It is known that the problem of advanced train-ing of specialists remains as insufficiently studied problem. As for systemic approach and its application in cognitive and other activity of students and experts it was never actualized in domestic education in general. We offer the ways of realization of this problem in development of the domestic education systemК перспективному направлению развития отечественной системы образования, на наш взгляд, необходимо отнести опережающую подготовку современных специалистов. При этом, как показали наши исследования, одним из главных условий реализации опережающего профессионального образования является системный подход и формирование на его основе у субъектов обучения и специалистов системных представлений и системного мышлени

Efficient optical-to-terahertz conversion in large-area InGaAs photo-Dember emitters with increased indium content

Optical-to-terahertz (THz) conversion of 800 nm femtosecond laser pulses in large-area bias-free InGaAs emitters based on photo-Dember (PD) and lateral photo-Dember (LPD) effects is experimentally investigated. We use metamorphic buffers to grow submicro-meter thick InxGa1-xAs layers with indium mole fractions x=0.37, 0.53, and 0.70 on a GaAs substrate. A strong enhancement of THz output energy with an increase of indium content is observed. On the surface of the sample providing the strongest emission (x=0.7), we have fabricated a 1.5 cm2 area of asymmetri-cally shaped metallic grating for LPD emission. This LPD emitter allows achieving high conversion efficiency of 0.24 . 10-3 and a broad generation band-width of up to 6 THz. We also demon-strate that there is no significant differ-rence in the conversion efficiency when operating at 1 and 200 kHz repetition rates. Our results show that large area LPD emitters give a convenient, competitive way to generate intense high-repetition-rate THz pulses

ПРОГНОЗИРОВАНИЕ СВОЙСТВ МЕТАЛЛА ПРИ СОВМЕЩЕННОЙ ОБРАБОТКЕ СПЛАВОВ СИСТЕМЫ Al–РЗМ НА ОСНОВЕ ПОЭТАПНОЙ ОЦЕНКИ ИХ МЕХАНИЧЕСКИХ ХАРАКТЕРИСТИК

The data of experimental studies on determining the mechanical properties of long-length deformed semifinished products in a form of bars and wire made of alloys of aluminum with rare-earth metals, which are fabricated using the combined treatment methods, are presented. The application of the combined technology of casting, rolling, and pressing makes it possible to increase the strength of hot-extruded rod by 15–20 % on average compared with combined rolling–extruding the cast billet formed in an electromagnetic crystallizer. It is also shown that a decrease in the REM content in the alloy leads to the strength reduction and an increase in plastic characteristics. Herewith, it is possible to control the level of physicomechanical characteristics of the final product varying the summary deformation ratio during drawing and applying annealing.Приведены данные экспериментальных исследований по определению механических свойств длинномерных деформируемых полуфабрикатов в виде прутков и проволоки из сплавов алюминия с редкоземельными металлами, полученных с использованием методов совмещенной обработки. Применение совмещенной технологии литья, прокатки и прессования дает возможность увеличить прочность горячепрессованных прутков в среднем на 15–20 % по сравнению с совмещенными процессами прокатки и прессования литой заготовки, полученной в электромагнитном кристаллизаторе. Показано также, что уменьшение содержания РЗМ в сплаве приводит к снижению прочностных и повышению пластических характеристик. При этом, варьируя величиной суммарной степени деформации при волочении и применяя отжиги, можноуправлять уровнем физико-механических характеристик конечной продукции

Innovative solutions implemented in design of iset tower

A significant increase in the construction of high-rise buildings in Russia is observed in the last decades. Ekaterinburg takes the second place in Russia after Moscow as regards the annual construction volumes. The first high-rise buildings in the Urals region were built as early as in 19th century and the height of these buildings reached approximately 75 meters. Nowadays, two northernmost skyscrapers in the world are located in Ekaterinburg, one of which is a part of a business district "Ekaterinburg-City". The height of these skyscrapers is above 150 meters. The incompleteness of the Russian regulatory basis for designing high-rise buildings makes it necessary to carry out a large amount of additional design and construction processes. Therefore, despite the experience of previous projects, designers have to create individual innovative design solutions for every new high-rise building. This article describes the features of design of the high-rise building is the Iset Tower, located in Ekaterinburg. Basic design conditions are described and architectural, planning, and design features of the building are reviewed. The effects of harmful factors, acting on the building frame and including the wind loads, are analyzed. Some distinctive features of the analysis of the bearing structures are given. The conclusion contains the summary on specifics of high-rise buildings design and construction in the Urals. © Published under licence by IOP Publishing Ltd

About the problems and perspectives of making precision compressor blades

The problems of manufacturing blades with high precision profile geometry are considered in the article. The variant of the technology under development rules out the use of mechanical processing methods for blades airfoil. The article consists of an introduction and six small sections.The introduction sets out the requirements for modern aircraft engines, makes a list of problems arisen in the process of their manufacturing, and marks the relevance of the work.The first section analyzes the existing technology of precision blades. There is an illustration reflecting the stages of the process. Their advantages and disadvantages are marked.The second section provides an illustration, which shows the system-based blades used in the manufacturing process and a model of the work piece using the technology being developed. An analysis of each basing scheme is presented.In the third section we list the existing control methods of geometrical parameters of blades airfoil and present the measurement error data of devices. The special attention is paid to the impossibility to control the accuracy of geometrical parameters of precision blades.The fourth section presents the advantages of the electrochemical machining method with a consistent vibration of tool-electrode and with feeding the pulses of technology current over the traditional method. The article presents data accuracy and surface roughness of the blades airfoil reached owing to precision electrochemical machining. It illustrates machines that implement the given method of processing and components manufactured on them.The fifth section describes the steps of the developed process with justification for the use of the proposed operations.Based on the analysis, the author argues that the application of the proposed process to manufacture the precision compressor blades ensures producing the items that meet the requirements of the drawing.</p

Robust optimization of the investment portfolio under uncertainty conditions

© 2019, Dorma Journals. All rights reserved. Of the goal of this study is to investigate the assessment of expected return parameters µ and return covariance matrices Σ in modern portfolio investment tasks. These parameters are used in almost all modern portfolio investment models, including the classic mean-variance Markowitz model, Black-Litterman model, “smart ”models. In practice, they are difficult to evaluate correctly, since the parameter values change every day. However, the quality of investment portfolio depends precisely on these parameters. The quality of investment portfolio is understood as a combination of risk and profitability parameters. Number of methodologies are used in this article to reduce the uncertainty of these parameters. The main idea of these methods is to reduce the sensitivity of resulting optimal portfolios to uncertain input parameters. In other words, if the parameter values µ and Σ change slightly, the final portfolio shall not radically change its structure. According the results gained in this article, one asset will not be able to dominate the final portfolio. Chopra offers using the James-Stein estimate for the expected averages, while Black and Litterman use the Bayesian estimate µ and Σ (taking into account the expert opinions). There are also selection methods and scenarios that are described in detail, for example, in. Of all these methods, the Black-Litterman model is most often used in practice