Снежники Лагонакского нагорья (Западный Кавказ)

The article presents results of investigation of snowfields on the Lagonaky plateau: conditions of their formation, distribution and dynamics. Snow patches are the most characteristic elements of the high-mountain landscapes of the Lagonaky plateau. In warm seasons, they are widely distributed on local flat-topped ridges of the Lagonaky: Abadzeshsh Murzikao, Kamennoe and others, as well as on the mountain masses Fisht, Pshehasu, Oshten, and Nagoychuk. Morphological and climatic conditions of the Lagonaky Highlands are unique and favorable for formation of snow patches and long preservation of them during the spring-summer periods. These conditions are high mountain ridges with flat tops, negative karst forms of the relief as well as a favorable wind regime with long winter snow storms and heavy snowfalls. Snow patches result from snow transport and accumulation after strong snow-drift on the leeward slopes. The avalanche snow patches arise when avalanches release from steep and long slopes of the above mountain ranges. Permanent snow patches are usually formed at the same places, and duration of their existence depends on sizes and a degree of shading. At the same time, even relatively small snow patches (100–200 thousand m3) can be preserved if they are located in narrow fissures (for example, the area of the Maly Fisht Glacier). In the last 3–5 years, the permanent snow patches melt completely, which is probably a result of small amount of solid precipitation during the cold season and the relatively high air temperatures in the warm time (standard deviation is 0.8–1.0 °C above the normal).Представлены новые данные о снежниках Лагонакского нагорья. Проанализировано их распределение в пределах нагорья с учётом особенностей рельефа и ветрового режима. Отмечено значительное сокращение числа снежников и их размеров за последние годы, что обусловлено общей климатической тенденцией потепления

The ART-XC telescope on board the SRG observatory

ART-XC (Astronomical Roentgen Telescope - X-ray Concentrator) is the hard X-ray instrument with grazing incidence imaging optics on board the Spektr-Roentgen-Gamma (SRG) observatory. The SRG observatory is the flagship astrophysical mission of the Russian Federal Space Program, which was successively launched into orbit around the second Lagrangian point (L2) of the Earth-Sun system with a Proton rocket from the Baikonur cosmodrome on 13 July 2019. The ART-XC telescope will provide the first ever true imaging all-sky survey performed with grazing incidence optics in the 4-30 keV energy band and will obtain the deepest and sharpest map of the sky in the energy range of 4-12 keV. Observations performed during the early calibration and performance verification phase as well as during the on-going all-sky survey that started on 12 Dec. 2019 have demonstrated that the in-flight characteristics of the ART-XC telescope are very close to expectations based on the results of ground calibrations. Upon completion of its 4-year all-sky survey, ART-XC is expected to detect ~5000 sources (~3000 active galactic nuclei, including heavily obscured ones, several hundred clusters of galaxies, ~1000 cataclysmic variables and other Galactic sources), and to provide a high-quality map of the Galactic background emission in the 4-12 keV energy band. ART-XC is also well suited for discovering transient X-ray sources. In this paper, we describe the telescope, results of its ground calibrations, major aspects of the mission, the in-flight performance of ART-XC and first scientific results.Comment: 19 pages, 30 figures, accepted for publication in Astronomy and Astrophysic

Snow patches of the Lagonaky highlands (Western Caucasus)

The article presents results of investigation of snowfields on the Lagonaky plateau: conditions of their formation, distribution and dynamics. Snow patches are the most characteristic elements of the high-mountain landscapes of the Lagonaky plateau. In warm seasons, they are widely distributed on local flat-topped ridges of the Lagonaky: Abadzeshsh Murzikao, Kamennoe and others, as well as on the mountain masses Fisht, Pshehasu, Oshten, and Nagoychuk. Morphological and climatic conditions of the Lagonaky Highlands are unique and favorable for formation of snow patches and long preservation of them during the spring-summer periods. These conditions are high mountain ridges with flat tops, negative karst forms of the relief as well as a favorable wind regime with long winter snow storms and heavy snowfalls. Snow patches result from snow transport and accumulation after strong snow-drift on the leeward slopes. The avalanche snow patches arise when avalanches release from steep and long slopes of the above mountain ranges. Permanent snow patches are usually formed at the same places, and duration of their existence depends on sizes and a degree of shading. At the same time, even relatively small snow patches (100–200 thousand m3) can be preserved if they are located in narrow fissures (for example, the area of the Maly Fisht Glacier). In the last 3–5 years, the permanent snow patches melt completely, which is probably a result of small amount of solid precipitation during the cold season and the relatively high air temperatures in the warm time (standard deviation is 0.8–1.0 °C above the normal)

MODERNIZATION OF THE DIRECT OPERATION FUEL FEEDING SYSTEM OF DIESEL ENGINE

This paper describes the way of modernization of the direct operation fuel feeding system of diesel engine. Effective, ecological and economical characteristics of a modern diesel engine are greatly de-termined by parameters of using fuel-feeding system. Thus, in modern conditions, fuel-feeding systems have to fulfil specified requirements, which are mainly connected with fuel supply process intensification, possibility of adaptable regulation of fuel injection lead angle, cycle fuel delivering and injection characteristic at full range of engine operation regimes. At present time accumulator fuel feeding systems Common Rail type, fulfil these requirements best of all. However, despite its advantages, those kinds of systems have number of disadvantages. The main ones are high price and structural complexity of the system elements. Because of this Common Rail does not have wide using in the diesel engines with number of cylinders less than three. Although that type of diesels exactly is universal mechanical energy, source and can be used in many types of machinery, including ones with strict ecological norms. However, up to now these engines are equipped with the direct operation fuel feeding system that despite its high reliability and low price is worse than accumulator systems in the injection pressure level and possibilities of fuel feeding process control. Thus, main objective of a modernization of the direct operation fuel feeding system is topical. Speed forcing of high-pressure fuel pump was used. Maximal injection pressure is successfully increased 1.42 times. It provides intensification of fuel injection process. Implementation of the electronic control allows counting this method of fuel feeding system modernization promising for small diesel engines

Modernization of the direct operation fuel feeding system of diesel engine

This paper describes the way of modernization of the direct operation fuel feeding system of diesel engine. Effective, ecological and economical characteristics of a modern diesel engine are greatly de-termined by parameters of using fuel-feeding system. Thus, in modern conditions, fuel-feeding systems have to fulfil specified requirements, which are mainly connected with fuel supply process intensification, possibility of adaptable regulation of fuel injection lead angle, cycle fuel delivering and injection characteristic at full range of engine operation regimes. At present time accumulator fuel feeding systems Common Rail type, fulfil these requirements best of all. However, despite its advantages, those kinds of systems have number of disadvantages. The main ones are high price and structural complexity of the system elements. Because of this Common Rail does not have wide using in the diesel engines with number of cylinders less than three. Although that type of diesels exactly is universal mechanical energy, source and can be used in many types of machinery, including ones with strict ecological norms. However, up to now these engines are equipped with the direct operation fuel feeding system that despite its high reliability and low price is worse than accumulator systems in the injection pressure level and possibilities of fuel feeding process control. Thus, main objective of a modernization of the direct operation fuel feeding system is topical. Speed forcing of high-pressure fuel pump was used. Maximal injection pressure is successfully increased 1.42 times. It provides intensification of fuel injection process. Implementation of the electronic control allows counting this method of fuel feeding system modernization promising for small diesel engines