排序方式： 共有63条查询结果，搜索用时 31 毫秒
1.
Astronomy Letters - The sensitivity of future far-infrared telescopes, such as Millimetron, will be limited by the confusion noise produced by distant galaxies. We have constructed a model of the... 相似文献
2.
Astronomy Reports - Within the framework of the model of the extragalactic background created earlier by the authors, the factors influencing the statistical properties of the confusion noise have... 相似文献
3.
O. V. Pilipenko Z. V. Sharonova V. M. Trubikhin 《Izvestiya Physics of the Solid Earth》2007,43(5):430-441
The lower part of the Roxolany section (Ukraine) is studied, and paleomagnetic and petromagnetic characteristics of rock samples are obtained for the time interval 300-75 ka. Detailed curves of variations in angular parameters of the geomagnetic field are constructed in the entire time interval, and curves of variations in the relative paleointensity are obtained for the interval 300-180 ka. Using the values of the angular parameters and the deviations of the virtual geomagnetic pole from the position of the stationary field, anomalous directions compatible with the Jamaica excursion are identified in the intervals 250-249 and 221-220 ka. The geomagnetic field evolution is studied by methods of wavelet analysis, and the field generation process is shown to vary in the interval 300-180 ka. 相似文献
4.
O. V. Pilipenko N. Abrahamsen V. M. Trubikhin 《Izvestiya Physics of the Solid Earth》2007,43(8):691-701
Petro-and paleomagnetic methods are applied to the study of the lower part of the Early Pleistocene Tuzla section on the Black Sea coast of the Taman Peninsula, This part of the section is composed of marine and lagoonal sediments deposited over the time interval 120–70 ka. The measured curves of the variation in the geomagnetic field inclination reveal an anomalous direction dated at ～110 ka that coincides with a similar anomalous direction in the Eltigen section (Ukraine) correlating with the Blake paleomagnetic event. The significant correlation between the time series NRM0.015/SIRM0.015 (Tuzla section) and the world composite Sint-800 curve indicates that the curve NRM0.015/SIRM0.015 in the interval 110–70 ka actually reflects the variation in the relative paleointensity of the geomagnetic field. 相似文献
5.
Sokolova E. Yu. Marshalko E. E. Kozyreva O. V. Kupriyanov I. S. Epishkin D. V. Pilipenko V. A. Slinchuk G. E. Yakovlev D. V. Yakovlev A. G. 《Izvestiya Physics of the Solid Earth》2022,58(5):670-689
Izvestiya, Physics of the Solid Earth - Abstract—The paper presents the results of analysis of the geoelectric (telluric) field variability during the Earth’s magnetic field... 相似文献
6.
V. N. Pilipenko A. O. Verpakhovskaya V. I. Starostenko N. I. Pavlenkova 《Izvestiya Physics of the Solid Earth》2010,46(11):943-954
The main results of deep seismic sounding (DSS) are usually presented in the form of high-velocity models of the medium. Some
model examples and the international DOBRE profile have shown that the informativeness of the data obtained can be significantly enhanced by the construction of wave
images of the Earth’s crust, based on the migration of refracted and wide-angle reflected waves. The Donets Basin Refraction/Reflection
Experiment (DOBRE) profile crosses the Dnieper-Donets paleorift zone in the Donbas region. Along the profile, refracted waves from the basement
and the upper mantle and the reflections from the crust basement (the M boundary) are reliably traced. This wave migration has been used to construct a wave image of the structure of the Earth’s
crust. As a result, a clear seismic image of the basement surface, whose depth changes along the profile from 0 to 20 km,
was obtained. In near-slope parts of the basin, several major faults were identified that had not been identified previously
during standard kinematic data processing. It is shown that the crust-upper mantle transition zone is a clearly reflective
horizon only within the crystalline massifs; under a depression, it is represented by a lens-shaped highly-heterogeneous area.
As shown in the model examples, the images obtained using such a migration accurately reflect the structural features of the
medium, in spite of its complicated structure. 相似文献
7.
O. V. Pilipenko V. M. Trubikhin H. Abrahamsen J. -P. Buylaert 《Izvestiya Physics of the Solid Earth》2010,46(12):1052-1063
During revisiting the Upper Pleistocene Pekla loess-soil section located on the Sea of Azov coast of the Taman Peninsula,
its lower 6 m were continuously sampled, which led to an increase in the age range from ∼50 to 400 ka. The detailed rock magnetic
study of the structure, grain-size, and concentrations of magnetic mineral (natural remanent magnetization (NRM) carrier)
in the collected rock samples revealed regular changes in rock magnetic characteristics along the section and their correlation
with climatic fluctuations. Magnetite and hematite both deposited during the transport of sedimentary material and formed
during pedogenesis, which involved the entire section to a varying extent, represent the main magnetic minerals in the examined
rocks. Automorphic paleosoils that were formed during warm and humid periods corresponding to odd stages of the MIS scale
are characterized by elevated concentrations of magnetic mineral (NRM, magnetic susceptibility (K
lf), saturation isothermal remanent magnetization (SIRM), and anhysteresis (ideal) remanent magnetization (ARM)) parameters
and share of superparamagnetic particles (up to 80%, according to elevated values of the frequency-dependent magnetic susceptibility
K
td) as well as by lowered rigidity parameter (B
cr) and grain size (ARM/K parameter). Such changes in the paleosoils may be explained by the occurrence of newly formed fine-grained magnetite particles
close in size to its superparamagnetic and single-domain varieties due to the activation of bio/geochemical processes during
warm stages. The growth of the above-mentioned rock magnetic parameters in automorphic soils may be considered as serving
a quantitative criterion for defining the boundary between warm and cold periods even in poorly developed soils. 相似文献
8.
Ballooning disturbances in a finite-pressure plasma in a curvilinear magnetic field are described by the system of coupled equations for the Alfvén and slow magnetosonic modes. In contrast to most previous works that locally analyzed the stability of small-scale disturbances using the dispersion relationship, a global analysis outside a WKB approximation but within a simple cylindrical geometry, when magnetic field lines are circles with constant curvature, is performed in the present work. This model is relatively simple; nevertheless, it has the singularities necessary for the formation of the ballooning mode: field curvature and non-uniform thermal plasma pressure. If the disturbance finite radial extent is taken into account, the instability threshold increases as compared to a WKB approximation. The simplified model used in this work made it possible to consider the pattern of unstable disturbances at arbitrary values of the azimuthal wavenumber (k y ). Azimuthally large-scale disturbances can also be unstable, although the increment increases with decreasing azimuthal scale and reaches saturation when the scales are of the order of the pressure nonuniformity dimension. 相似文献
9.
The composition, granulometry data, and concentration of grains that carry the natural remanent magnetization (NRM) are studied
in the bottom 6.5 meters of the loess-soil deposits of the Pekla section (Azov coast, Krasnodar region). It was shown that
these strata, which correspond to the 9th–11th marine oxygen isotope stages (MIS) and cover the time interval ∼425–300 ka,
are suitable for further paleomagnetic investigation. The deposits in the upper portion of the Inzhavino paleosoils (Likhvin
Interstadial) contain the records of anomalous deviations of the direction of magnetization from the dipole field at the sampling
site. The studied interval was sampled by taking two hand blocks from four sampling levels, which minimizes the errors due
to the specimen cutting. This anomaly dated ∼300 ka possibly corresponds to the Biva-II geomagnetic excursion. However, the
studies of implications of anisotropy in magnetic susceptibility (AMS) for the direction of natural remanent magnetization
(NMR) have shown that parts of the samples from the Inzhavino paleosoils and the underlying loess horizon are magnetically
anisotropic, which is characteristic for biogenic magnetite grains, while other parts of the samples exhibit plane anisotropy
typical for natural sedimentary structures. A weak correlation between the time series of averaged curves of relative paleointensity,
NRM20/ARM20 (and NRM20/K) for the loess horizons of the Pekla section and the global composite reference curve of relative paleointensity, Sint-800,
in the time intervals 200–130 ka and 370–320 ka indicates that the paleomagnetic records have been imprinted not only on the
detritic magnetic grains but also on the grains produced by chemical reactions and the life processes of bacteria. 相似文献
10.
One of the reference sections of Maeotian deposits in the south of Russia (the Popov Kamen section) is studied in terms of rock magnetism and paleomagnetism within the framework of the project “Study of Reference Sections of the Taman Downwarp as a Basis for Developing a Detailed Event Scale of the Neogene of the Eastern Paratethys.” The section is located in the southwestern part of the Taman Peninsula, to the south of the Taman Cape. It has been established that the lower-Maeotian deposits carry the magnetization of mainly reversed polarity, whereas the upper-Maeotian deposits are characterized by normal polarity. Two horizons of normally magnetized rocks are recognizable against the background of reversely magnetized lower-Maeotian deposits. A horizon of reversely magnetized rocks is outlined in the upper part of the upper Maeotian. If the paleomagnetic interpretation of the section is true, it can be concluded that the upper part of the upper Maeotian is absent in this section. Comparison with the magnetochronological scale shows that the lower Maeotian probably corresponds to the C3Br, C3Bn, and C3Ar Chrons, and the part of the upper Maeotian studied in this section corresponds to the lower part of the C3An Chron. 相似文献