BVRI CCD-Photometry of comparison stars in the fields of galaxies with active nuclei. V     

V. T. Doroshenko  S. G. Sergeev  Yu. S. Efimov  G. A. Borman  D. N. Okhmat  N. G. Pulatova  S. V. Nazarov 《Astrophysics》2013,56(3):343-358

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Nutrient Input into the Caspian Sea with River Runoff     

Leonov  A. V.  Nazarov  N. A. 《Water Resources》2001,28(6):656-665

Long-term observational data are used to compare and analyze time and space variations in the concentrations of nutrients in the water of major rivers flowing into the Caspian Sea and assess the nutrients runoff into the sea. Annual variations in the normal monthly values of river runoff and nutrient compound concentrations and input into the sea are considered (18 compounds and considered for the Volga, Ural, Terek, Sulak, and Samur, and 7 compounds are considered for the Kura). The Volga contribution to nutrient input into the sea is found to vary from 77 to 94% with the average of 86%.  相似文献   

Methods and Results of Numerical Modeling of Reactive Solute Transport in River Flow   总被引：1，自引：0，他引：1  

Nazarov  N. A.  Demidov  V. N. 《Water Resources》2001,28(1):34-41

The equation of advection–diffusion transport of a reactive solute in a stream is solved by different methods. Procedures for evaluating the parameters of a four-node finite-difference approximation used to numerically integrate this equation are proposed. Numerical experiments based on the developed numerical procedures, software, and models of solute transport allowed, in particular, the evaluation of the sensitivity of pollutant concentration estimates to variations in the parameters of interaction processes and hydrodynamic dispersion for a lowland river.  相似文献   

Efremovka 101.1: a CAI with ultrarefractory REE patterns and enormous enrichments of Sc, Zr, and Y in Fassaite and Perovskite     

A. El Goresy  E. ZinnerS. Matsunami  H. PalmeB. Spettel  Y. LinM. Nazarov 《Geochimica et cosmochimica acta》2002,66(8):1459-1491

Inclusion 101.1 from the CV3 carbonaceous chondrite Efremovka is a compact Type A Ca-Al-rich inclusion (CAI) highly enriched in ultrarefractory (UR) oxides. It is the first complete CAI with a UR rare earth element (REE) pattern found in a CV3 chondrite. The inclusion is petrographically complex and was formed in a multistage process. It consists of several lithologically unrelated units.The core contains abundant Y- and Zr-perovskite, Sc- and Zr-rich fassaite, and metallic FeNi enclosed in melilite. All mineral species (except spinel) in all lithological units exhibit the same basic UR REE pattern. Four different populations of perovskites are distinguished by different Y/Zr ratios. A few of the perovskites have Y/Zr ratios similar to those obtained from crystal/liquid fractionation experiments. Perovskites from the other three populations have either chondritic, lower than chondritic Y/Zr ratios or extremely low Zr contents. Ca isotopic ratios differ among three perovskites from different populations, demonstrating a variety of sources and formational processes. Most fassaites crystallized in situ through reaction between the CAI liquid and preexisting perovskites. This process induced redistribution of Zr, Y, Sc, and V between perovskite and fassaite, thus overprinting the original abundances in perovskite. Fassaite reaction rims around FeNi metals are also encountered. They are enriched in V, which was gained from the metal through oxidation of V in metal during fassaite crystallization. The relative abundances of Zr, Y, and Sc in perovskites are complementary to the abundances of these elements in Sc- and Zr-fassaite, indicating subsolidus partitioning of these elements between the two phases. Perovskites are enriched in Y and depleted in Sc and Zr in comparison to fassaites.The core contains two complete captured CAIs, several sinuous fragments, and fine-grained polygonal refractory fragments. An assemblage of andradite-wollastonite-hedenbergite and pure metallic iron is encountered as enclaves in the interior of some sinuous fragments. Metallic Fe and wollastonite formed by reduction of preexisting andradite and hedenbergite nebular alteration products upon inclusion in the highly reduced CAI melt. Numerous spinel clusters and framboids with varying V₂O₃ and Cr₂O₃ concentrations are enclosed in individual melilite crystals in the host CAI and captured CAIs. The rim sequence of the host consists of six layers (from the inside outward): (a) FeO-poor spinel, (b) Sc-bearing fassaite, (c) Al-diopside, (d) Al- and Ca-bearing olivine, (e) pure diopside, and (f) Ca-poor olivine. Like the constituents of the CAI core, all mineral layers of the rim sequence, except spinel, have the same UR REE pattern. However, the total REE abundances decrease systematically by 1 order of magnitude from layer 2 to layer 6. This feature strongly suggests formation of the rim sequence by successive condensation from a unique reservoir enriched in UR elements and excludes formation by flash heating. Petrography, mineral chemistry, REE, refractory lithophile element abundances, and Ca isotopic compositions demonstrate the complex multistage formation history of a CAI that on the surface looks like a regular Type A inclusion.  相似文献   

Acoustic method for defining the stress state of a rock massif based on solution of the seismic inverse problem     

L. A. Nazarov  L. A. Nazarova  E. I. Romenskii  V. A. Tcheverda  M. I. Epov 《Doklady Earth Sciences》2016,466(2):210-213

A method for estimating the stress–strain state of a rock massif in the vicinity of underground facilities is substantiated. This method is based on solution of the boundary inverse problem of defining the components of an external stress field from the acoustic sounding data. The acoustic sounding data used are the arrival times of diving head longitudinal waves, recorded in a long mine shaft. Numerical experiments have revealed the optimal arrangement of the recording network and the limited relative error in the input data, which, taken together, provide for solvability of the inverse problem.  相似文献   

Cosmic ray exposure age and time of formation of a new meteorite,Dhofar 007 achondrite from Oman: A rock fragment from the asteroid Vesta   总被引：1，自引：0，他引：1  

Yu. A. Shukolyukov  M. A. Nazarov  E. V. Korochantseva 《Petrology》2007,15(1):1-18

The isotopic composition of noble gases was investigated in the Dhofar 007 meteorite. Petrographic and mineralogical observations suggested that it is a brecciated cumulate eucrite with high contents of siderophile elements. The concentrations of noble gases in Dhofar 007 are identical to those of other eucrites. Its cosmic ray exposure age was estimated as 11.8 ± 0.8 Ma, which coincides with a maximum on the histogram of comic ray exposure ages of eucrite meteorites. It can be supposed that, similar to other eucrites, Dhofar 007 was ejected from the surface of their parent body (presumably, asteroid Vesta) about 12.0 Ma ago. The crystallization age of the Dhofar 007 eucrite was estimated from the ratio of plutonogenic Xe to Nd as 4476 ± 22 Ma. The potassium-argon age is much younger, 3.7–4.1 Ga, which indicates partial loss of radiogenic argon during the history of the meteorite, most likely related to impact metamorphic events.  相似文献   

Use of Programs for Two-Parameter Multiple Impulse Correction of Altitude and Inclination of Circular Orbits     

A. E. Nazarov 《Solar System Research》2018,52(7):613-621

The paper describes the method for the development of programs for two-parameter multiple impulse correction of altitude and inclination of circular orbits. The considered corrections feature the simultaneous adjustment of altitude and inclination of the orbit under limited thrust of the propulsion system of the spacecraft. Low thrust-to-weight ratio of the spacecraft leads to the need for a correction program consisting of several burns of the propulsion system. Thrust vector orientation, burn time, and its operation duration are determined as propulsion system parameters.  相似文献   

Orbital Motion and Attitude Control of the Spectrum–Röntgen–Gamma Space Observatory     

Eismont  N. A.  Kovalenko  I. D.  Nazarov  V. N.  Nazirov  R. R.  Korotkov  F. V.  Pogodin  A. V.  Mzhelskii  P. V.  Mikhailov  E. A.  Ditrikh  A. V.  Tregubov  A. I. 《Astronomy Letters》2020,46(4):263-274

Astronomy Letters - The Spectrum–Röntgen–Gamma (SRG) space observatory was launched from Baikonur on July 13, 2019, and is currently on a flight trajectory in the vicinity of the...  相似文献   

Positioning and control of the orbital structure of the <Emphasis Type="Italic">Arktika-M</Emphasis> innovative space system (marking the 50 years of Lavochkin Association’s space activities)     

A. E. Nazarov 《Solar System Research》2016,50(7):568-574

The orbital positioning options and orbital structure control methods are considered for the Arktika-M highly elliptical hydrometeorological space system, which is designed for continuous 24-hour imaging of the Earth’s Arctic region. The purpose of the control is to ensure on-going performance during the entire operational life of the space system given a major spatial and temporal deformation of its orbital structure due to the nonuniform evolution of the orbital parameters. The highly elliptical Molniya orbits are considered. The proposed control procedure is based on the minimization of the spatial and temporal deformation of the orbital structure by means of the differential choice of the initial orbital parameters during the deployment and follow-up of the space system.  相似文献   

Lunar regolith breccia Dhofar 287B: A record of lunar volcanism     

S. I. Demidova  M. A. Nazarov  M. Anand  L. A. Taylor 《Meteoritics & planetary science》2003,38(4):501-514

Abstract— Dhofar 287 (Dho 287), a recently found lunar meteorite, consists in large part (95%) of low‐Ti mare basalt (Dho 287A) and a minor, attached portion (?5%) of regolith breccia (Dho 287B). The present study is directed mainly at the breccia portion of this meteorite. This breccia consists of a variety of lithic clasts and mineral fragments set in a fine‐grained matrix and minor impact melt. The majority of clasts and minerals appear to have been mainly derived from the low‐Ti basalt suite, similar to that of Dho 287A. Very low‐Ti (VLT) basalts are a minor lithology of the breccia. These are significantly lower in Mg# and slightly higher in Ti compared to Luna 24 and Apollo 17 VLT basalts. Picritic glasses constitute another minor component of the breccia and are compositionally similar to Apollo 15 green glasses. Dho 287B also contains abundant fragments of Mg‐rich pyroxene and anorthite‐rich plagioclase grains that are absent in the lithic clasts. Such fragments appear to have been derived from a coarse‐grained, Mg#‐rich, Na‐poor lithology. A KREEP component is apparent in chemistry, but no highlands lithologies were identified. The Dho 287 basaltic lithologies cannot be explained by near‐surface fractionation of a single parental magma. Instead, magma compositions are represented by a picritic glass; a low‐Ti, Na‐poor glass; and a low‐Ti, Na‐enriched source (similar to the Dho 287A parental melt). Compositional differences among parent melts could reflect inhomogeneity of the lunar mantle. Alternatively, the low‐Ti, Na‐poor, and Dho 287A parent melts could be of hybrid compositions, resulting from assimilation of KREEP by picritic magma. Thus, the Dho 287B breccia contains lithologies from multiple magmatic eruptions, which differed in composition, formational conditions, and cooling histories. Based on this study, the Dho 287 is inferred to have been ejected from a region located distal to highlands terrains, possibly from the western limb of the lunar nearside, dominated by mare basalts and KREEP‐rich lithologies.  相似文献