Ophiolites of Western Tyva as fragments of a late Vendian Island arc of the Paleoasian ocean     

Mongush  A. A.  Lebedev  V. I.  Travin  A. V.  Yarmolyuk  V. V. 《Doklady Earth Sciences》2011,438(2):866-872

Doklady Earth Sciences -  相似文献   

Comparative analysis of pollution of the surface atmospheric layer in such megalopolises as Moscow and Beijing     

A. V. Andronova  M. A. Iordanskii  A. V. Trefilova  V. A. Lebedev  V. M. Minashkin  Yu. I. Obvintsev  M. S. Artamonova  I. G. Granberg 《Izvestiya Atmospheric and Oceanic Physics》2011,47(7):819-827

The results of simultaneous investigations of atmospheric aerosol in two large megalopolises—Moscow and Beijing—are presented. The purpose of these investigations was to compare parameters and reveal common characteristics of urban aerosols. Aerosol parameters were measured in the megalopolises simultaneously from October 23, 2007, through November 2, 2007. The mass concentrations of aerosols were measured continuously with a nephelometer (Mosscow) and discretely with the use of aspiration samplers according to the weight method (Moscow, Beijing). The number concentration and the particle size distribution function were determined with analyzers of the size spectrum in the interval 0.15–15.0 μm and were measured synchronously with sampling for elementary analysis. The elementary compositions of samples were determined by mass spectrometry, which made it possible to identify 60 chemical elements.  相似文献   

Stellar content of the metal-poor galaxy DDO 68     

N. A. Tikhonov  O. A. Galazutdinova  V. S. Lebedev 《Astronomy Letters》2014,40(1):1-10

Based on archival Hubble Space Telescope ACS/WFC images, we have performed stellar photometry for the metal-poor galaxy DDO 68. The apparent distributions of stars of different ages and stellarmetallicity determinations indicate that DDO68 is a systemof two galaxies that have different stellar metallicities (Z = 0.004 and 0.001) and are in the stage of interaction or merging. We have determined the distance to DDO 68, D = 12.0 ± 0.3 Mpc, which differs significantly from previous estimates of the distance to this system. A concentration of red giants is observed outside DDO 68. This can be interpreted as the periphery of a partially visible low-surface-brightness galaxy located at the same distance as DDO 68. Comparison of the constructed CM diagrams with theoretical isochrones from Bertelli et al. has allowed us to determine that the age of each galaxy is at least 10 Gyr.  相似文献   

MHD Models and Laboratory Experiments of Jets     

T.A. Gardiner  A. Frank  E.G. Blackman  S.V. Lebedev  J.P. Chittenden  D. Ampleford  S.N. Bland  A. Ciardi  M. Sherlock  M.G. Haines 《Astrophysics and Space Science》2003,287(1-4):69-74

Jet research has long relied upon a combination of analytical, observational and numerical studies to elucidate the complex phenomena involved. One element missing from these studies (which other physical sciences utilize) is the controlled experimental investigation of such systems. With the advent of high-power lasers and fast Z-pinch machines it is now possible to experimentally studysimilar systems in a laboratory setting. Such investigations can contribute in two useful ways. They can be used for comparison with numerical simulations as a means to validate simulation codes. More importantly, however, such investigations can also be used to complement other jet research, leading to fundamentally new knowledge. In the first part of this article, we analyze the evolution of magnetized wide-angle winds in a collapsing environment. We track the ambient and wind mass separately and describe a physical mechanism by which an ionized central wind can entrain the ambient gas giving rise to internal shells of molecular material on short time scales. The formation of internal shells in molecular outflows has been found to be an important ingredient in describing the observations of convex spurs in P-V diagrams (Hubble wedges in M-V diagrams).In the second part, we present astrophysically relevant experiments in which supersonic jets are created using a conical wire array Z-pinch. The conically convergent flow generates a standing shock around the axis which collimates the flow into a Mach ～ 30 jet. The jet formation process is closely related to the work of Cantó et al. (1988) for hydrodynamic jet collimation. The influence of radiative cooling on collimation and stability is studied by varying the wire material (Al, Fe, and W).  相似文献   

Nonlinear evolution of the atmosphere above a seismic epicenter: 1. Analytical estimates     

V. A. Pavlov  S. V. Lebedev 《Geomagnetism and Aeronomy》2013,53(6):794-803

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Observations of global oscillations of the sun in the SOKOL experiment onboard the CORONAS-PHOTON satellite     

N. I. Lebedev  V. D. Kuznetsov  Yu. D. Zhugzhda  S. I. Boldyrev 《Solar System Research》2011,45(3):200-205

The helioseismological experiment onboard the CORONAS-PHOTON satellite is intended for the study of characteristics and the internal structure of the Sun using the solar eigenmodes spectrum obtained by the measurement of fluctuations of the solar radiation intensity. This experiment is the continuation of investigations of solar global oscillations started onboard artificial satellites CORONAS-I and CORONAS-F. Measurements of fluctuations of the solar radiation intensity in seven optical ranges—from the near ultraviolet to infrared spectral regions—are carried out by the solar photometer SOKOL (SOlnechnye KOLebaniya (Solar Oscillations)) developed at IZMIRAN. Over an instrument operation period of more than 9 months, a large volume of the scientific information (more than 500 MB) has been obtained. The primary processing of obtained data was performed, and spectra of fluctuations of the solar radiation intensity were constructed. On the basis of part of the processed information obtained by the photometer SOKOL, and data of the experiment DIFOS (Differential Oscillations of the Sun) onboard the artificial satellite CORONAS-F, the dependence of the relative amplitude of oscillations on the wavelength of the observation was determined.  相似文献   

Experimental Studies of Magnetically Driven Plasma Jets     

F. Suzuki-Vidal  S. V. Lebedev  S. N. Bland  G. N. Hall  G. Swadling  A. J. Harvey-Thompson  G. Burdiak  P. de Grouchy  J. P. Chittenden  A. Marocchino  M. Bocchi  A. Ciardi  A. Frank  S. C. Bott 《Astrophysics and Space Science》2011,336(1):41-46

We present experimental results on the formation of supersonic, radiatively cooled jets driven by pressure due to the toroidal magnetic field generated by the 1.5 MA, 250 ns current from the MAGPIE generator. The morphology of the jet produced in the experiments is relevant to astrophysical jet scenarios in which a jet on the axis of a magnetic cavity is collimated by a toroidal magnetic field as it expands into the ambient medium. The jets in the experiments have similar Mach number, plasma beta and cooling parameter to those in protostellar jets. Additionally the Reynolds, magnetic Reynolds and Peclet numbers are much larger than unity, allowing the experiments to be scaled to astrophysical flows. The experimental configuration allows for the generation of episodic magnetic cavities, suggesting that periodic fluctuations near the source may be responsible for some of the variability observed in astrophysical jets. Preliminary measurements of kinetic, magnetic and Poynting energy of the jets in our experiments are presented and discussed, together with estimates of their temperature and trapped toroidal magnetic field.  相似文献   

SYSTEMS MAPPING OF THE PHYSICAL-GEOGRAPHIC PROCESS IN A MARINE ENVIRONMENT     

V. L. Lebedev 《地理信息系统科学与遥感》2013,50(2):156-165

An analog to the (terrestrial) physical-geographical process, the concept of boundary surfaces, is elaborated and developed quantitatively for analyzing the diversity of marine ecosystems. Interactions among physical-chemical components of the oceans, and the adjacent coastal, atmospheric, and ocean bottom environments, provides a model used in the study and mapping of heterogeneous “waterscapes.” A series of tables identifies interacting geographic features commonly used as indices for mapping. Sample maps prepared for the Barents Sea and Indian Ocean demonstrate possible results of a systems approach. Translated from: Izvestiya, Vsesoyuznogo geograficheskogo obshchestva, 1985, No. 3, pp. 201-208.  相似文献   

Geochronology of miocene volcanism in the northern part of the Lesser Caucasus (Erusheti Highland, Georgia)     

Vl. A. Lebedev  I. V. Chernyshev  G. T. Vashakidze  M. V. Gudina  A. I. Yakushev 《Doklady Earth Sciences》2012,444(1):585-590

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Convergent boundaries and related igneous and metamorphic complexes in caledonides of Central Asia     

I. K. Kozakov  E. B. Sal’nikova  V. V. Yarmolyuk  A. M. Kozlovsky  V. P. Kovach  P. Ya. Azimov  I. V. Anisimova  V. I. Lebedev  G. Enjin  Ch. Erdenejargal  Yu. V. Plotkina  A. M. Fedoseenko  S. Z. Yakovleva 《Geotectonics》2012,46(1):16-36

Fragments of the crystalline complexes where Vendian metamorphism of moderate and elevated pressure predated Early Paleozoic metamorphism have been established in the accretionary-collisional domain of the eastern segment of the Central Asian Foldbelt (Early Caledonian superterrane of Central Asia). The geodynamic setting of the Vendian (??560?C570 Ma) South Hangay metamorphic belt located in the junction zone of the Baydrag Block and the Late Riphean (??665 Ma) ophiolite complex of the Bayanhongor Zone is considered. The origination of this belt was related to the formation of the convergent boundary in the framework of the Zabhan microcontinent about 570 Ma ago. At the same time, an island-arc complex was formed in the paleo-oceanic domain. Metamorphism of elevated pressure indicates that Vendian structures with sufficiently thick continental crust were formed in the framework of the continental blocks. Vendian metamorphism is also established in the Tuva-Mongolia Massif and the Kan Block of the Eastern Sayan. These data show that the Late Baikalian stage predated the evolution of the Early Caledonian superterrane of Central Asia. The development of its accretionary-collisional structure was accompanied by Late Cambrian-Early Ordovician low-pressure regional metamorphism. Granulite-facies conditions were reached only at the deep levels of the accretionary-collisional edifice. The outcrops of crystalline complexes in the southern framework of the Caledonian paleocontinent are regarded as fragments of the Early Paleozoic Central Mongolian metamorphic belt.  相似文献