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11.
Kuleshova A. I. Dergachev V. A. Kudryavtsev I. V. Nagovitsyn Yu. A. Ogurtsov M. G. 《Geomagnetism and Aeronomy》2018,58(8):1097-1102
Geomagnetism and Aeronomy - The results of the reconstruction of Wolf numbers from the 11th century until the middle of the 19th century A.D. based on radiocarbon data are presented. This time span... 相似文献
12.
Reconstruction of the Production Rate of Cosmogenic 14C in the Earth’s Atmosphere for 17 000–5000 BC
Kudryavtsev I. V. Volobuev D. M. Dergachev V. A. Nagovitsyn Yu. A. Ogurtsov M. G. 《Geomagnetism and Aeronomy》2018,58(7):925-929
Geomagnetism and Aeronomy - Carbon isotope 14С is produced in the Earth’s atmosphere by energetic cosmic-ray (CR) particles. The data on its atmospheric abundance are used to... 相似文献
13.
Geomagnetism and Aeronomy - Reconstruction of summer temperature at subarctic Fennoscandia (68°–70° N, 20°–30° E), based on tree-ring data, was compared with three... 相似文献
14.
The nonlinear dynamics of long-wave perturbations of the inviscid Kolmogorov flow, which models periodically varying in the horizontal direction oceanic currents, is studied. To describe this dynamics, the Galerkin method with basis functions representing the first three terms in the expansion of spatially periodic perturbations in the trigonometric series is used. The orthogonality conditions for these functions formulate a nonlinear system of partial differential equations for the expansion coefficients. Based on the asymptotic solutions of this system, a linear, quasilinear, and nonlinear stage of perturbation dynamics is identified. It is shown that the time-dependent growth of perturbations during the first two stages is succeeded by the stage of stable nonlinear oscillations. The corresponding oscillations are described by the oscillator equation containing a cubic nonlinearity, which is integrated in terms of elliptic functions. An analytical formula for the period of oscillations is obtained, which determines its dependence on the amplitude of the initial perturbation. Structural features of the field of the stream function of the perturbed flow are described, associated with the formation of closed vortex cells and meandering flow between them. As a supplement, an asymptotic analysis of nonlinear dynamics of long-wave perturbations superimposed on a damped by small viscosity Kolmogorov flow (very large, but finite Reynolds numbers) is made. It is strictly shown that all velocity components of the perturbed flow remain bounded in this case. 相似文献
15.
Geomagnetism and Aeronomy - Long-term correlations between the state of low clouds and variations in the flux of galactic cosmic rays (GCRs) were studied. It has been shown that the links between... 相似文献
16.
G. E. Kocharov I. V. Kudryavtsev M. G. Ogurtsov E. Sonninen H. Jungner 《Astronomy Reports》2000,44(12):825-829
Past solar activity is studied based on analysis of data on the nitrate content of Greenland ice in the period from 1576–1991. Hundred-year (over the entire period) and quasi-five-year (in the middle of the 18th century) variations in the nitrate content are detected. These reflect the secular solar-activity cycle and cyclicity in the flare activity of the Sun. 相似文献
17.
M. G. Ogurtsov 《Geomagnetism and Aeronomy》2010,50(4):475-481
Data on the concentrations of the cosmogenic 10Be isotope and Na+ and Ca2+ ions, as well as on ice accumulation rates in central Greenland, obtained by the GISP2 collaboration were studied in a time
interval spanning about 40 000 recent years. Joint analysis of the indicated glacial and chemical paleoseries demonstrated
that in a period from 12 008 to 24 008 years ago, the 10Be flux variations were most free of influence of climate and changes in the geomagnetic dipole moment. As a consequence,
this time interval is most suitable for studying periodicities of purely solar nature. Statistical analysis of the 10Be flux data has revealed significant variations with periods of 500–800 years and 1300–1600 years in the time interval from
12 008 to 17 008 years ago. This evidence favors the existence of the appropriate cycles of solar activity in the mentioned
epoch. Similar periodicities are also revealed in the time interval from 3288 to 8008 years ago. 相似文献
18.
Alireza Malehmir Magnus Andersson Maxim Lebedev Milovan Urosevic Vassili Mikhaltsevitch 《Geophysical Prospecting》2013,61(1):153-167
To provide a guide for future deep (<1.5 km) seismic mineral exploration and to better understand the nature of reflections imaged by surface reflection seismic data in two mining camps and a carbonatite complex of Sweden, more than 50 rock and ore samples were collected and measured for their seismic velocities. The samples are geographically from the northern and central parts of Sweden, ranging from metallic ore deposits, meta‐volcanic and meta‐intrusive rocks to deformed and metamorphosed rocks. First, ultrasonic measurements of P‐ and S‐wave velocities at both atmospheric and elevated pressures, using 0.5 MHz P‐ and S‐wave transducers were conducted. The ultrasonic measurements suggest that most of the measured velocities show positive correlation with the density of the samples with an exception of a massive sulphide ore sample that shows significant low P‐ and S‐wave velocities. The low P‐ and S‐wave velocities are attributed to the mineral texture of the sample and partly lower pyrite content in comparison with a similar type sample obtained from Norway, which shows significantly higher P‐ and S‐wave velocities. Later, an iron ore sample from the central part of Sweden was measured using a low‐frequency (0.1–50 Hz) apparatus to provide comparison with the ultrasonic velocity measurements. The low‐frequency measurements indicate that the iron ore sample has minimal dispersion and attenuation. The iron ore sample shows the highest acoustic impedance among our samples suggesting that these deposits are favourable targets for seismic methods. This is further demonstrated by a real seismic section acquired over an iron ore mine in the central part of Sweden. Finally, a laser‐interferometer device was used to analyse elastic anisotropy of five rock samples taken from a major deformation zone in order to provide insights into the nature of reflections observed from the deformation zone. Up to 10% velocity‐anisotropy is estimated and demonstrated to be present for the samples taken from the deformation zone using the laser‐interferometery measurements. However, the origin of the reflections from the major deformation zone is attributed to a combination of anisotropy and amphibolite lenses within the deformation zone. 相似文献
19.
20.
Maxim Yu.Khlopov 《中国天文和天体物理学报》2010,10(6)
Primordial black holes (PBHs) are a profound signature of primordial cos-mological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to re-strict a wide range of particle physics models, predicting an enhancement of the ul-traviolet part of the spectrum of density perturbations, early dust-like stages, first or-der phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflation-ary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds. 相似文献