Magnon topological transition in skyrmion crystal

We study the magnon spectrum in skyrmion crystal formed in thin ferromagnetic films with Dzyalosinskii-Moria interaction in presence of magnetic field. Focusing on two low-lying observable magnon modes and employing stereographic projection method, we develop a theory demonstrating a topological transition in the spectrum. Upon the increase of magnetic field, the gap between two magnon bands closes, with the ensuing change in the topological character of both bands. This phenomenon of gap closing, if confirmed in magnetic resonance experiments, may deserve further investigation by thermal Hall conductivity experiments.Comment: 6 pages, 4 figure

SOME FEATURES OF CURRENT TECHNOGENIC MOVEMENTS OF THE EARTH’S CRUST

We describe the history of studying the current crustal movements by various methods and discuss technogenic effects recorded at large water-reservoir zones and mineral deposits in Siberia. Initially, classical surveying techniques aimed to obtain high-accuracy ground-based measurements of height, tilt and direction. Modern geodesy techniques and methods for measuring absolute gravity are now available to investigate displacement, deformation, tilt and other phenomena taking place on the Earth’s surface. These methods are used to estimate kinematic parameters of the crust areas (e.g. rates of subsidence and horizontal movements) and to monitor fluid motions in mineral deposits. Such data are critical for ensuring a proper management of the mineral deposits. In this article, we analyse technogenic processes observed in the Ust Balyk oil-gas field, the Zapolyarny gas deposit, the water-reservoir zone at the Sayano-Shushenskaya hydroelectric power station (SSHPS) on the Yenisei river, and large open-pit mines in the Kuzbass basin. Our analysis is based on surface displacement rates estimated from the data collected in different periods of observations at large man-made facilities. In the study of the hydro technical objects, we estimated the displacement rates at 5.0 mm per year. In the northern areas of the West Siberian petroleum basin, subsidence rates amounted to 20–25 mm per year in the early 2000s. These estimates were supported by the high-accuracy gravity measurements showing an increase up to 6–7 microGal per year in the oil-gas field development areas. We assess a possibility of triggering effects related to weak seismicity due to a high stress accumulation rate (1 KPa per hour) in the SSHPS area. A connection between earth tides and catastrophic events, such as gas emissions in high amounts on mining sites, is discussed. Having analysed the surface monitoring records taken in South Primorye in September 2017, we conclude that underground nuclear explosions in North Korea in this period did not cause any significant displacement of the surface in this most southerly region of the Russian Far East territories

Guided random walk calculation of energies and <\sq {r^2} > values of the 1Σg^1\Sigma_g state of H_2 in a magnetic field

Energies and spatial observables for the $^1\Sigma_g$ state of the hydrogen molecule in magnetic fields parallel to the proton-proton axis are calculated with a guided random walk Feynman-Kac algorithm. We demonstrate that the accuracy of the results and the simplicity of the method may prove it a viable alternative to large basis set expansions for small molecules in applied fields.Comment: 10 pages, no figure

Hybrid light source with spectra close of series «D» standard illuminant

Description of the developed hybrid multispectral light source with a spectrum close to the CIE standard illuminant series D represents. The emitters of the source is a halogen lamp with interference filters and LEDs. The source has the ability to control the value of correlated color temperature. The design is suitable for laboratory research and for visual inspection of color samples of industrial products.Представлено описание разработанного мультиспектрального гибридного источника освещения со спектром близким к стандартному осветителю MKO серии D. Излучателями источника являются галогенные лампы с интерференционными фильтрами и светодиоды. Источник имеет возможность управления значением коррелированной цветовой температуры. Разработка пригодна как для лабораторных исследований, так и для визуального контроля цвета образцов промышленной продукции

СОВРЕМЕННЫЕ ДВИЖЕНИЯ ЗЕМНОЙ ПОВЕРХНОСТИ ГОРНОГО АЛТАЯ ПО GPS-НАБЛЮДЕНИЯМ

In 2000–2017, the GPS technology was first applied to study inter-seismic, co-seismic and post-seismic processes in the crust of the Altai Mountains (Gorny Altai). Our study aims at investigating the fields of displacement and deformation in the Gorny Altai region as a part of Asia.The 3D displacement fields are reconstructed for the period before the M 7.3 Chuya earthquake that occurred in the southern sector of the Altai GPS network (49° to 55°N, and 81° to 89°E)on 27 September 2003.Anomalous behavior features are discovered in the displacement orientations, as well as in the distribution of velocities and deformation in the zone of the future earthquake.The spatial displacement pattern defined for the period of co-seismic displacements corresponds to the right-lateral strike-slip along the vertical fault. The fault depth is estimated using the elastic model and the experimental data (change in displacement from 0.30 m to 0.02 m at the distances of 14 km and 84 km from the fault, respectively); it amounts to 8–10 km.The co-seismic deformation field is investigated.In the post-seismic stage (2004–2017), displacements revealedin the epicentral zone show the right-lateral strike-slip along the fault at the rate of 2 mm/yr. Therefore, two-layer viscoelastic models can be considered. The estimated viscosity of the lower crust ranges from 6×1019 to 3×1020Pa×s, and the elastic upper crust thickness is 25 km. Analyzed are modern movements in the Gorny Altai region outside the Chuya earthquake area.The results of our study show that modern horizontal displacements occur in the NNW direction at the rate of 1.1 mm/yr, which is twice lower than the displacement rate before the earthquake.Технология космической геодезии впервые использована для изучения межсейсмических, косейсмических и постсейсмических процессов в земной коре Горного Алтая с 2000 по 2017 г. Показано место Горного Алтая в полях смещений и деформаций Азии. Получены поля 3D смещений перед Чуйским землетрясением (27.09.2003г., М=7.3), произошедшим в южной части Алтайской GPS-сети (от 49° до 55° с.ш. и от 81° до 89° в.д.). Выделено аномальное поведение в ориентации смещений, в распределении скоростей и деформаций в зоне будущего землетрясения. В эпоху косейсмических смещений получено распределение смещений, соответствующее правостороннему сдвигу на вертикальном разрыве. С использованием экспериментальных данных (изменение смещения от 0.3 м в 14 км от разрыва до 0.02 м в 84 км) и упругой модели получена оценка глубины разрыва (8–10 км). Исследовано поле косейсмических деформаций. Для постсейсмического этапа (2004–2017 гг.) выделяются смещения в эпицентральной зоне. Они повторяют правостороннее движение (скорость 2 мм/год) на разрыве, что позволило рассмотреть двухслойные вязкоупругие модели, оценить вязкость нижней коры (6×1019–3×1020 Па×с) и мощность упругой верхней (25 км). Проанализированы современные движения Горного Алтая вне области Чуйского землетрясения. Величина современных горизонтальных смещений составила 1.1 мм/год при направлении на ССЗ (–30°). Скорость смещения оказалась более чем в два раза меньше значений скоростей перед землетрясением.

Excitonic condensation in a symmetric electron-hole bilayer

Using Diffusion Monte Carlo simulations we have investigated the ground state of a symmetric electron-hole bilayer and determined its phase diagram at T=0. We find clear evidence of an excitonic condensate, whose stability however is affected by in-layer electronic correlation. This stabilizes the electron-hole plasma at large values of the density or inter-layer distance, and the Wigner crystal at low density and large distance. We have also estimated pair correlation functions and low order density matrices, to give a microscopic characterization of correlations, as well as to try and estimate the condensate fraction.Comment: 4 pages, 3 figures, 2 table

Hardware and software solutions for the control of multispectral illuminators

Предложено унифицированное комплексное решение для управления компонентами в мультиспектральных источниках освещения. В работе приведены принципиальные электронные схемы, осуществляющие регулировку яркости компонентов с помощью ШИМ, либо изменением рабочего тока. Линейность изменения яркости обеспечивается программным обеспечением.Unified integrated solution for managing components in multispectral light sources represent. Described the fundamental electronic circuits, components performing brightness adjustment using PWM, or change the operating current. Dimming linearity provided by the software