Spin waves in diluted magnetic quantum wells

We study collective spin excitations in two-dimensional diluted magnetic semiconductors, placed into external magnetic field. Two coupled modes of the spin waves (the electron and ion modes) are found to exist in the system along with a number of the ion spin excitations decoupled from the electron system. We calculate analytically the spectrum of the waves taking into account the exchange interaction of itinerant electrons both with each other and with electrons localized on the magnetic ions. The interplay of these interactions leads to a number of intriguing phenomena including tunable anticrossing of the modes and a field-induced change in a sign of the group velocity of the ion mode

Заметки о лапчатках (Potentilla, Rosaceae) Алтая. 1. Новый гибрид из Восточного Казахстана

A new nothospesies of Potentilla, P. × jakovlevii from East Kazakhstan is described and illustrated. It is an intersectional hybrid purportedly between P. chrysantha (P. sect. Chrysanthae) and P. longifolia (P. sect. Tanacetifoliae).Приводится описание и иллюстрация нового для науки нотовида из рода Potentilla. Собранная на территории восточной части Казахстана Potentilla × jakovlevii представляет собой межсекционный гибрид P. chrysantha (P. sect. Chrysanthae) × P. longifolia (P. sect. Tanacetifoliae)

Морфология спор Parahemionitis arifolia (Cheilanthoideae, Pteridaceae)

A study of spores of the single species of the genus Parahemionitis Panigrahi was performed using the method of scanning electronic microscopy (SEM). Spores of Parahemionitis arifolia (Burm. f.) Panigrahi are tetrahedral trilete, roundish-triangular in polar position, with micro-wrinkled exospore and sculptured perispore. Sculpture of perispore is cristate-reticulate, cristae are quite regularly distributed and form reticulum with small mostly closed polygonal luminae of different shape. Laesura arms are often obscured by numerous cristae. Size of spores is 53–63 × 40–42 μm. Spores of P. arifolia are similar in perispore sculpture with those of species of some cheilanthoid ferns

РОД GYPSOPHILA (CARYOPHYLLACEAE) В АЛТАЙСКОЙ ГОРНОЙ СТРАНЕ

Diversity, synonymy and distribution of species of Gypsophila L. in Altai Mountain Country is revised. Original key to the species determination is presented. The synopsis of Gypsophila includes 10 species from 3 subgenera and 5 sections. The name G. desertorum is typified.Приведен видовой состав, распространение, а также синонимика для видов рода Gypsophila L., произрастающих на территории Алтайской горной страны. Составлен оригинальный ключ для определения видов и конспект рода Gypsophila, включающий 10 видов, относящихся к 3 подродам и 5 секциям. Типифицировано название G. desertorum

Конспект рода Anopteris (Pteridophyta, Pteridaceae)

In the article a synopsis of the genus Anopteris (Prantl) Diels is given. The synopsis of Anopteris includes three species. For each species, the Latin name, basionym, nomenclatural citation, synonyms, information on locus classicus, type, habitat, and distribution are given. An original key for identification of the species of Anopteris is also prepared. The localities of occurrence of each species are precisely given. Приведен конспект рода Anopteris (Prantl) Diels. Конспект включает три вида. Для каждого из них приводится латинское название, базионим, номенклатурная цитата, синонимы, откуда описан, информация о типе, данные о местообитании, распространение по странам с цитированием мест сбора и общее распространение. Для определения всех видов рода Anopteris составлен оригинальный ключ, указаны подробные места произрастания. Приведен конспект рода Anopteris (Prantl) Diels. Конспект включает три вида. Для каждого из них приводится латинское название, базионим, номенклатурная цитата, синонимы, откуда описан, информация о типе, данные о местообитании, распространение по странам с цитированием мест сбора и общее распространение. Для определения всех видов рода Anopteris составлен оригинальный ключ, указаны подробные места произрастания.

Comparison of induction heating parameters of various billets

In this paper, we consider the induction heating of various forms of blanks using a laboratory Autoclave. The thermal and energy characteristics are compared.В данной работе рассматривается индукционный нагрев различных форм заготовок с помощью лабораторной установки Автоклав. Проводится сравнение тепловых и энергетических характеристик

Верификация пакетов для расчета течений жидкости в канале при действии внешнего магнитного поля

In this paper, the authors present the results of software verification for solving magnetohydrodynamic problem in duct exposed to constant magnetic fields. The proposed approach uses the following open source software: OpenFOAM for solving problems of continuum mechanics using the finite volume method, Elmer for solving magnetic field distribution based on the finite element method, and EOF-library for data exchange between these two programs. The verification results were demonstrated by fluid flow in a square duct exposed to constant uniform spanwise magnetic field. The research was carried out with a laminar fluid flow, which makes it similar to the Hartmann's problem. The existing experience of calculating such problems, their verification and application were discussed. The paper provides a brief mathematical description of the proposed solution and basic procedures for implementing the code proposed by the authors. At the first stage of verification, the comparison of fluid velocity distribution results at Hartmann’s numbers equal to 1, 10, 20 and 50 was demonstrated. These results were obtained by means of proposed software, an analytical solution, and a test problem provided by OpenFOAM developers for two-dimensional case. At the second stage of software verification, sufficient convergence of the results was shown for fluid velocity distribution in the three-dimensional case of the Hartmann’s problem compared with the OpenFOAM test problem data and the results obtained by Comsol Multiphisics and ANSYS. As a result, distributions of the fluid flow velocity between Hartmann’s walls were obtained for various study cases: a two-dimensional problem, a three-dimensional problem with electrically insulated walls, and a three-dimensional problem with walls having infinite electrical conductivity. The last stage of the study corresponds to assessing of software performance in comparison with the built-in OpenFOAM solver and commercial software Comsol Multiphysics and ANSYS. It was found that the proposed approach takes more time to calculate these problems than the built-in OpenFOAM solver, but less than Comsol. However, the problem formulation in EOF-library allows solving problems with complex geometry, which is not available in the built-in OpenFOAM solver. In conclusion, analysis of computation performance with parallelization was carried out. It showed significant reducing of computation time with the help of EOF-library in comparison with the commercial software Comsol and ANSYS. © 2021 Leibniz University. All right reserved.This work was supported by the RFBR (Project 20-38-90237)

Spin instability criteria based on parametric identification of the node distribution in Trace transform direct image of the SHS combustion wave chronogram

The article gives examples of virtual chronograms of the propagation of a combustion wave in the diffusion, thermal, and spin instabilities of the SHS process. It is shown that the use of high-speed video recording allows one to reliably determine the moment of occurrence of the spin instability of the SHS combustion wave by differential chronoscopy methods. As a criterion for the recognition of spin instability, we selected the sign of the appearance of local maxima in the central transversal region of the spectrum of the trace transform. It is concluded that the spin instability is characteristic of the transition from the thermal to diffusion instability, in the presence of a hysteretic dependence of the burning rate on temperature.The work is supported by Russian Foundation for Basic Research in scientific projects No. 18-08-01475 and 18-41-220004