819 research outputs found
Plasmonic nanostructures with local temporal response: a platform for time-varying photonics
This work is devoted to the development of an approach for implementation and designing time-varying media. A mechanism based on the use of plasmonic nanostructures with a reduced plasmon lifetime is proposed. It is shown that such nanostructures can be used to enhance the strength and speed of modulation of the refractive index ofnonlinear media. This is achieved through decreasing of the spectral dispersion of the real permittivity. Plasmonic materials with peculiar optical properties, such as flatdispersion in the near-infrared range, were synthesized. For this purpose, we prepared TiON thin films and performed thermal post-treatment for fine-tuning permittivity of TiON. It has been shown that the proposed materials allow one to achieve an ultrashort plasmon lifetime on the order of 0.1 fs, which is an order of magnitude shorter than in the case of traditional plasmonic materials
Subexponential estimations in Shirshov's height theorem (in English)
In 1993 E. I. Zelmanov asked the following question in Dniester Notebook:
"Suppose that F_{2, m} is a 2-generated associative ring with the identity
x^m=0. Is it true, that the nilpotency degree of F_{2, m} has exponential
growth?" We show that the nilpotency degree of l-generated associative algebra
with the identity x^d=0 is smaller than Psi(d,d,l), where Psi(n,d,l)=2^{18} l
(nd)^{3 log_3 (nd)+13}d^2. We give the definitive answer to E. I. Zelmanov by
this result. It is the consequence of one fact, which is based on combinatorics
of words. Let l, n and d>n be positive integers. Then all the words over
alphabet of cardinality l which length is greater than Psi(n,d,l) are either
n-divided or contain d-th power of subword, where a word W is n-divided, if it
can be represented in the following form W=W_0 W_1...W_n such that W_1 >'
W_2>'...>'W_n. The symbol >' means lexicographical order here. A. I. Shirshov
proved that the set of non n-divided words over alphabet of cardinality l has
bounded height h over the set Y consisting of all the words of degree <n.
Original Shirshov's estimation was just recursive, in 1982 double exponent was
obtained by A.G.Kolotov and in 1993 A.Ya.Belov obtained exponential estimation.
We show, that h<Phi(n,l), where Phi(n,l) = 2^{87} n^{12 log_3 n + 48} l. Our
proof uses Latyshev idea of Dilworth theorem application.Comment: 21 pages, Russian version of the article is located at the link
arXiv:1101.4909; Sbornik: Mathematics, 203:4 (2012), 534 -- 55
Strong focusing higher-order laser modes: Transverse and longitudinal optical fields
© Published under licence by IOP Publishing Ltd. The distribution of transverse and longitudinal optical fields in tightly focused higher-order laser beams is investigated. Polarization-dependent fingerprints of transverse and longitudinal optical fields are experimentally captured by means of photoinduced surface deformations in azobenzene polymer thin films
Oscillations of Induced Magnetization in Superconductor-Ferromagnet Heterostructures
We study a change in the spin magnetization of a superconductor-ferromagnet
(SF) heterostructure, when temperature is lowered below the superconducting
transition temperature. It is assumed that the SF interface is smooth on the
atomic scale and the mean free path is not too short. Solving the Eilenberger
equation we show that the spin magnetic moment induced in the superconductor is
an oscillating sign-changing function of the product of the exchange field
and the thickness of the ferromagnet. Therefore the total spin magnetic
moment of the system in the superconducting state can be not only smaller
(screening) but also greater (anti-screening) than that in the normal state, in
contrast with the case of highly disordered (diffusive) systems, where only
screening is possible. This surprising effect is due to peculiar periodic
properties of localized Andreev states in the system. It is most pronounced in
systems with ideal ballistic transport (no bulk disorder in the samples, smooth
ideally transparent interface), however these ideal conditions are not crucial
for the very existence of the effect. We show that oscillations exist (although
suppressed) even for arbitrary low interface transparency and in the presence
of bulk disorder, provided that ( -- mean free path). At
low interface transparency we solve the problem for arbitrary strength of
disorder and obtain oscillating magnetization in ballistic regime () and nonoscillating magnetization in diffusive one () as
limiting cases of one formula.Comment: 10 pages, 2 figures, accepted for publication in Phys. Rev.
ЦИКЛОКОНВЕРТОР С КОМБИНИРОВАННЫМ ЗАКОНОМ УПРАВЛЕНИЯ ДЛЯ СИСТЕМ ЭЛЕКТРОСНАБЖЕНИЯ АВТОНОМНЫХ ОБЪЕКТОВ
The present paper considers cycle-converter with complicated control law. The methodj complicated control law generating is presented. The scheme of power circuits is introduced. Volta and current curves for classical cycle-converter and cycle-converter with complicated control lawi discussed. Introducing of complicated control law improves output voltage quality, increa fundamental harmonic's amplitude and input power factor. The article is attractive in the field of i power electronics.В статье рассматривается циклоконвертер с комбинированным законом управления вентильными комплектами. Представлен способ формирования комбинированного сигнала управления. Приведена схема силовых цепей исследуемого преобразователя. Рассматриваются эпюры кривых выходного напряжения и тока для классической схемы циклоконвертера и для схемы преобразователя с комбинированным законом управления. Введение комбинированного сигнала управления повышает качество выходного напряжения, увеличивает амплитуду основной гармоники и входной коэффициент мощности. Статья представляет интерес для специалистов в области авиационной силовой электроники.В статье рассматривается циклоконвертер с комбинированным законом управления вентильными комплектами. Представлен способ формирования комбинированного сигнала управления. Приведена схема силовых цепей исследуемого преобразователя. Рассматриваются эпюры кривых выходного напряжения и тока для классической схемы циклоконвертера и для схемы преобразователя с комбинированным законом управления. Введение комбинированного сигнала управления повышает качество выходного напряжения, увеличивает амплитуду основной гармоники и входной коэффициент мощности. Статья представляет интерес для специалистов в области авиационной силовой электроники
Проект ЭСПЦ по производству нержавеющих марок стали в условиях Урала производительностью 650 тыс. тонн стали в год
Реферат
Выпускная квалификационная работа 131 листов, 13 рисунков, 36 источников, 2 приложения.
Ключевые слова: электросталеплавильный цех, электродуговая печь, АКР, электрофильтр, МНЛЗ, блюм.
Объектом исследования является ЭСПЦ производительностью 650 тыс. тонн в год нержавеющих марок стали в условия Урала.
Цели исследования: выбор основного оборудования, расчет цеха и оборудования, баланса металла и шихты в цехе, социальная ответственность и экономическое обоснование строительства цеха.
Работа представлена введением, 5 разделами и заключением, список использованных источников.
В разделе 슫Объект исследования슻 описан проектируемый ЭСПЦ, рассмотрены основные пролеты и располагающееся в них оборудование.
Во разделе 슫Расчеты и аналитика슻 представлены расчет баланса металла в цехе и шAbstract
Abstract
The graduation work consists of 131 pages, 13 figures, 36 sources, 2 appendices.
Keywords: arc furnace plant, electric arc furnace, AOD, electrostatic precipitator, continuous casting machines, bloom.
The object of study is the EAF shop with the capacity of 650 thousand tons a year of stainless steels under the conditions of the Urals.
The aim of the study: choice of the basic equipment, calculation of plant and equipment, the balance of metal and charge in the plant, social responsibility and economic feasibility of the plant construction.
The work includes the introduction, 5 sections and conclusion, list of references.
In the section «Object of study» describe the designed EAF shop, considere the main spans and equipment located in them.
In the section «Calculation a
Геодинамическая модель глубинного строения палеосубдукционной зоны на восточной окраине Русской палеоплиты и распределение месторождений нефти и газа
Known hypothesis of M. Barazangi that quasilinear geological and tectonic zones represent the banded structures, which are parallel to the Urals paleo volcanic mountain belt was used. These zones can be in some interval of distances from a mountain paleo volcanic belt. On the size of this interval (~ 103 km) and the periodical arrangement of quasilinear geological and tectonic zones (of about ~ 300 km width), the paleo subduction speed (~ 5 – 6 cm a year) was estimated on the example of some Siberian regions.Использована известная гипотеза M. Barazangi о том, что квазилинейные геолого-тектонические зоны представляют собой полосчатые структуры, которые параллельны палеовулканическому Уральскому горному поясу и могут находиться в пределах некоторого интервала расстояний от пояса. По величине этого интервала (~10 3 км) и периодическому расположению квазилинейных геолого-тектонических зон (с поперечным размером ~ 300 км) оценивается скорость палеосубдукции (~ 5 – 6 см в год) на примере некоторых районов Сибири. Альтернативой столь высокой скорости палеосубдукции может быть угол палеосубдукции значительно меньше 10°. Результаты расчета могут быть применимы при изучении древних и современных литосферных блоков
Coulomb interaction and magnetic catalysis in the quantum Hall effect in graphene
The dynamics of symmetry breaking responsible for lifting the degeneracy of
the Landau levels in the integer quantum Hall effect in graphene is studied in
a low-energy model with the Coulomb interaction. The gap equation for Dirac
quasiparticles is analyzed for both the lowest and higher Landau levels, taking
into account the Landau levels mixing. It is shown that the characteristic
feature of the long-range Coulomb interaction is the decrease of the gap
parameters with increasing the Landau level index ("running" gaps). The
renormalization (running) of the Fermi velocity as a function of is also
studied. The solutions of the gap equation reproduce correctly the
experimentally observed integer quantum Hall plateaus in graphene in strong
magnetic fields.Comment: 22 pages, 5 figures; Final version published in the Proceedings of
the 2010 Nobel Symposium on Graphene and Quantum Matte
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