27 research outputs found
High-energy charged particle bursts in the near-Earth space as earthquake precursors
Get PDFInternational audienceThe experimental data on high-energy charged particle fluxes, obtained in various near-Earth space experiments (MIR orbital station, METEOR-3, GAMMA and SAMPEX satellites) were processed and analyzed with the goal to search for particle bursts. Particle bursts have been selected in every experiment considered. It was shown that the significant part of high-energy charged particle bursts correlates with seismic activity. Moreover, the particle bursts are observed several hours before strong earthquakes; L-shells of particle bursts and corresponding earthquakes are practically the same. Some features of a seismo-magnetosphere connection model, based on the interaction of electromagnetic emission of seismic origin and radiation belt particles, were considered. Key words. Ionospheric physics (energetic particles, trapped; energetic particles, precipitating; magnetosphere-ionosphere interactions
Spatial distribution of high-energy protons in the inner radiation belt, according to data from the ARINA and VSPLESK satellite experiments
No full textCorrelation between high-energy electron bursts and gamma-ray bursts associated with thunderstorm activity in near-Earth space
No full textThe correlation between the gamma-ray flashes and electron bursts associated with thunderstorm activity in the near-Earth space
No full textInterrelation between energy and time distributions of high- energy electrons during the observation of the particle bursts in the near-Earth space
No full textЭкспериментальное исследование широкополосной антенной решетки К-диапазона с использованием структур из искусственного неоднородного диэлектрика
Get PDFIntroduction. As a result of the extensive development of broadband communication in the millimetre wave band, there has arisen a need for antenna systems with a high level of directivity and compact dimensions, capable of operating across wide frequency ranges. However, at present, few engineering solutions satisfy this demand.Aim. To develop and study experimentally a K-band antenna array (AR) characterized by a high aperture efficiency and compact longitudinal dimensions.Materials and methods. Computer simulations were performed using the CST Studio Suite software. Measurements were carried out using an Agilent E8363B PNA vector circuit analyzer. Radiation patterns were obtained by the method of near-field scanning.Results. A K-band broadband antenna array configuration operating over the 18…26 GHz range was pro-posed. It was found that the period of the array equals 2.25 wavelengths at the highest operating frequency. In order to suppress grating lobes, an additional layer consisting of artificial inhomogeneous dielectric lenses was used. The dielectric material consisted of thin curly layers of sheet polyethylene terephthalate. Additionally, a hybrid configuration of feeding network was proposed, in which one part of the network was developed by means of printed two-wire lines, while the other part was achieved by means of rectangular waveguides. The proposed antenna array demonstrates VSWR of less than 2 and an aperture efficiency above 0.5, side and diffractive lobe levels not exceed –12 in the 18…26 GHz range. The total thickness of the configuration equals 50 mm or 4.3λmin. In order to ensure the compactness of the AR for wideband frequency applications, the thickness of the system can be reduced to 2.5λmin by excluding the waveguide part.Conclusion. When compared with existing solutions, the proposed antenna has a simpler feed network, which yields better matching. High aperture efficiency is achieved in the wide frequency range by means of inhomogeneous dielectric lenses.Введение. В связи с освоением миллиметрового диапазона и развитием средств широкополосной связи имеется потребность в антенных системах, которые работали бы в широкой полосе частот (порядка октавной), имели высокую направленность и компактные размеры. Имеющиеся решения, как правило, не удовлетворяют данным требованиям.Цель работы. Конструирование и экспериментальное исследование антенной решетки (АР) К-диапазона, обладающей высоким коэффициентом использования площади (КИП) и малыми продольными размерами. Материалы и методы. Численные исследования проводились в САПР СВЧ (CST Studio Suite), экспериментальные исследования – на оборудовании для векторного анализа СВЧ-цепей (Agilent E8363B PNA). Характеристики направленности измерялись методом сканирования ближнего поля.Результаты. Предложен вариант реализации широкополосной АР К-диапазона (18…26 ГГц). Период АР составляет 2.25 длины волны на верхней частоте диапазона. Для подавления дифракционных лепестков использован дополнительный слой, состоящий из линз из искусственного неоднородного диэлектрика, сформированный из тонких фигурных слоев листового полиэтилентерефталата. Предложена гибридная конфигурация диаграммообразующей схемы (ДОС), в которой одна часть схемы выполнена на основе печатных двухпроводных линий передачи, а другая – на прямоугольных волноводах. АР имеет КСВ ниже 2 и КИП выше 0.5, уровень боковых и дифракционных лепестков не превышает –12 в диапазоне 18…26 ГГц. Суммарная толщина всей системы составила 50 мм, что равно 4.3λmin. Если из конструкции исключить волноводную часть, толщина может быть уменьшена до 2.5λmin что обеспечивает компактность АР при широкой полосе рабочих частот.Заключение. По сравнению с имеющимися решениями антенна имеет более простую ДОС, за счет чего улучшается согласование с фидером. За счет применения линз из неоднородного диэлектрика обеспечивается высокий апертурный КИП в широкой полосе частот
First Multy-Proxy Studies Of High-Mountain Lakes In Armenia: Preliminary Results
Get PDFWithin the framework of the Russian-Armenian project “The Paleolimnological Aspect of Studying the Evolution of Ecosystems of High-Mountain Lakes of Russia and Armenia” in July-August 2018, we investigated four high-mountain lakes of Armenia. The research focuses on the lakes Kari, Umroi, Akna and Sev. All investigated lakes are located at the altitudes about 3000 m above sea level. We first time these lakes were investigated using a multi-proxy method that includes paleolimnological, geomorphological, hydrological, geochemical and biogeographic studies. The research offers the first statistical characteristics of lake depth distribution, water volume and other morphometrics. Lake sediments sequences and radiocarbon dates were received and analyzed for Armenian small lakes for the first time. We determined that all the studied lakes were formed during the Holocene. Sediments of Lake Kari were deposited in the last 4000 years, sediments of Lake Umroi – within the last 8000 years, while maximum thickness of sediments is around 1 m in both lakes. Hence, we assume low deposition rate in Armenian high-mountain lakes, however, it varied significantly in different periods of lake history
Time variations of proton flux in Earth inner radiation belt during 23/24 solar cycles based on the PAMELA and the ARINA data
Get PDFThe PAMELA and the ARINA experiments are carried out on the board of satellite RESURS-DK1 since 2006 up to now. Main goal of the PAMELA instrument is measurements of high energy antiparticles in cosmic rays while the ARINA instrument is intended studying high energy charged particle bursts in the magnetosphere. Both of these experiments have a possibility to study trapped particles in the inner radiation belt. Complex of these two instruments covers proton energy range from 30 MeV up to trapping limit (E= ∼2 GeV). Continuous measurements with the PAMELA and the ARINA spectrometers include falling and rising phases of 23/24 solar cycles and maximum of 24 th one. In this report we present temporal profiles of proton flux in the inner zone of the radiation belt (1.11 < L < 1.18, 0.18 < B < 0.22G). Dependence of proton fluxes on a magnitude of the solar activity was studied for various phases of 23/24 solar cycles. At that it was shown that proton fluxes at the solar minimum are several times greater than at the solar maximum
Solar modulation of galactic cosmic rays during 2006-2015 based on PAMELA and ARINA data
No full textSolar modulation of galactic protons with energies from 50 MeV up to dozens of GeV during July '06 - January '16 studied based on a data of the magnetic spectrometer PAMELA and scintillation spectrometer ARINA. This period is interesting because it covers the end of 23rd and current 24th cycles of solar activity, including the abnormally long transient period and change of the polarity of solar magnetic field
