排序方式： 共有34条查询结果，搜索用时 15 毫秒
21.
N. L. Dobretsov A. A. Kirdyashkin A. G. Kirdyashkin I. N. Gladkov N. V. Surkov 《Petrology》2006,14(5):477-491
Thermochemical plumes develop at the core-mantle boundary in the presence of a heat flow from the outer core and at local chemical doping that decreases the melting temperature near the bottom of the lower mantle (this dope triggers the melting of the mantle material and the ascent of the plume). The paper presents evaluations for the heat power of the Hawaiian and Iceland plumes and the results of the experimental modeling of a thermochemical plume. The diameter of a plume conduit was determined to remain virtually unchanging in the course of plume ascent. When the top of a plume reaches a “refractory” layer, whose melting temperature is higher than the melt temperature in the plume conduit, a mushroom-shaped head of the plume develops beneath the bottom of this layer. The analysis of geological and geophysical data and the results of experimental modeling are used to develop a thermal physical model for a thermochemical plume. The balance relations for the mass and thermal energy and systematic tendencies in the heat and mass transfer during free convection were utilized to derive a system of equations for the heat and mass transfer of a thermochemical plume. Parameters were determined for a thermochemical plume ascending from the core-mantle boundary. Geodynamic processes are considered that occur during the ascent of a plume before it reaches the surface. The effect of the P-T conditions on the shape and size of a plume roof is analyzed, and a model is proposed for mass transfer between a thermochemical plume and the lithosphere, when the plume reaches the bottom of a “refractory” layer in the lithosphere. 相似文献
22.
The phenomenological model of condensation interaction between galactic cosmic rays (GCRs) and water vapor, which makes it possible to estimate atmospheric pressure variations at different altitudes with changing GCR flux, has been developed. It has been indicated that pressure should increase at all altitudes in the considered interval (0–5 km above sea level) during Forbush decreases. Therefore, the correlation between pressure and GCR flux under mountain conditions can be negative as near sea level. However, the performed calculation of the cross-correlation function of the series of daily data, obtained at Jungfraujoch station (3475 m) in 1968–1992, indicated that this correlation is positive and statistically significant with a maximum leading the GCR variation onset by two days. As usual, pressure increased during Forbush decreases due to the condensation mechanism. The obtained results can be explained by the manifestation of the optical mechanism related to solar flares, which operates together with the condensation mechanism and causes a decrease in pressure at high altitudes. It has been indicated that the effectiveness of this mechanism substantially changes with the phase of the quasibiennial cycle. 相似文献
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Dobretsov N. L. Zhmodik S. M. Lazareva E. V. Tolstov A. V. Belyanin D. K. Surkov O. N. Dobretsov N. N. Rodionov N. V. Sergeev S. A. 《Doklady Earth Sciences》2019,489(1):1352-1357
Doklady Earth Sciences - In the northern part of the Siberian Platform, east of the Anabar Shield, several massifs of alkaline rocks with carbonatites identified (Tomtor, Bogdo, Promezhutochnyi)... 相似文献
24.
A spherical plasma inhomogeneity located at mesospheric altitudes in a thundercloud quasi-electrostatic field is considered as a possible cause of sprite formation. A simple semianalytical model of ionization instability in a quasi-electrostatic field, the value of which is larger than the air breakdown value, is developed on the assumption that plasma ball conductivity is controlled by impact ionization and electron attachment to neutrals. After several simplifications, the problem is reduced to a system of ordinary differential equations for the average conductivity and plasma ball radius. The analytical estimates and numerical simulation indicate that the predicted expansion rate and acceleration of the plasma inhomogeneity boundary are close in magnitude to the values observed during high-speed imaging of sprite development. 相似文献
25.
The Patlak-Keller-Segel population density flow equation was derived based on the hypotheses concerning the way of movement
of the benthic organisms with periodic appearance in the water mass differing from the commonly used assumptions [12, 14,
15]. On the basis of these hypotheses, a time-discrete and space-continuous individual-based model of the population distribution
in the environment with the continuous stimulus distribution was built. Using this model, we have shown that the analyzed
taxis mechanism (i.e., the decrease of the migration frequency of the individuals from the bottom to the water mass with the
increase of the stimulus concentration) leads to the aggregation of the organisms in the places with a high concentration
of the stimulus. The population dynamics is well approximated by the continuous model in which the obtained Patlak-Keller-Segel
flow equation is used. The numerical modeling has shown that the form of the dependence of the individual migration frequency
to the water mass on the stimulus concentration (hyperbolic, exponential, linear, and sigmoid) slightly influences the pattern
of the individuals’ distribution. 相似文献
26.
A. S. Zavadskii A. K. Il’yasov S. N. Ruleva V. V. Surkov L. A. Turykin R. S. Chalov 《Geography and Natural Resources》2013,34(1):26-33
We examine the transformation of a gentle segmental to a meander loop with the result that the city, founded in the 17th century, found itself on the caving bank. Comparison of cartographic materials from different times showed the occurrence of secondary bends on elongated rectilinear wings. Not only did such an evolution of the meanders lead to the caving of the terraced urban bank, but also it involved a likely emergency situation on the underwater crossing of the pipeline, and on other engineering facilities. We ascertained the causes of the ongoing channel deformations; modeling data were used in developing recommendations on meander straightening in order to divert the river away from the city. 相似文献
27.
Magritsky D. V. Samokhin M. A. Goncharov A. V. Erina O. N. Sokolov D. I. Surkov V. V. Tereshina M. A. Mikhailyukova P. G. Semenova A. A. 《Water Resources》2022,49(5):845-859
Water Resources - The Agrakhan Bay of the Caspian Sea is a unique hydrographic and environmentally valuable object at the mouth of the Terek River. At the beginning of the 20th century, it was a... 相似文献
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29.
Mars-96 mission: Mars exploration with the use of penetrators 总被引：1，自引：0，他引：1
Within the frames of the Mars-96 Mission the penetrators were first developed for the investigation of the chemical composition and physical properties of the Martian rocks, research into the internal structure of the planet, studying of its surface, atmosphere and climate.The paper briefly describes the penetrator design, the process of its landing and penetration into the Martian surface, items included in the complex scientific instrumentation and their specifications, and principal scientific tasks which can be realized with the use of penetrators. 相似文献
30.
V.V. Surkov Y. Matsudo M. Hayakawa S.V. Goncharov 《Journal of Atmospheric and Solar》2010,72(5-6):448-456
Spectrograms and ELF power spectra of magnetic variations originated from sprite-producing lightning discharges have been analyzed to extract both parent lightning and sprite parameters. Some of the spectrograms and power spectra have been found to have approximately quasi-oscillatory shape in the frequency range 0–40 Hz with maximum repetition period about 15–20 Hz. A theory predicts that this interesting peculiarity of the power spectra can be due to interference between electromagnetic fields originated from the parent lightning discharge and from the sprite. A smooth envelope of the power spectrum was shown to have a form of damped oscillations with period close to reciprocal value of sprite lag time. A technique of extracting sprite parameters based on the sprite-producing lightning power spectrum is proposed. The lack of the first Schumann resonance and other features occasionally observed in spectral resonance structure were also discussed. 相似文献