Hybrid Surface Waves from a Harmonic Perturbation Source

The problem of constructing uniform asymptotics of surface perturbations of far fields from a localized harmonic source in the flow of a heavy homogeneous fluid of infinite depth is considered. It is shown that the wave pattern of generated far fields at specific parameters is a system of hybrid wave disturbances that simultaneously possesses the properties of waves of two types: annular (transverse) and wedgeshaped (longitudinal) waves. The properties of the phase structure and wave fronts of the generated fields are studied. Uniform asymptotics of the solutions describing hybrid surface wave disturbances far from a harmonic source are constructed.     

Far Fields of Internal Gravity Waves from a Nonstationary Source

Oceanology - The problem of far fields of internal gravity waves from a nonstationary source moving in a stratified ocean of finite depth is considered. It is shown that the wave pattern of the...     

Thermochronology of the Angara–Vitim Granitoid Batholith,Transbaikalia, Russia

Doklady Earth Sciences - We reconstructed the history of the Angara–Vitim batholith (AVB), characterized by the formation of huge volumes of granitic magma using thermochronological analysis...     

A new mechanism for pulsar gamma-ray emission

Gamma-ray emission in pulsar magnetospheres is attributed to synchrotron radiation, which tends to decrease the pitch angle of the particle, being balanced by plasma processes tending to increase the pitch angle. The plasma processes are non-resonant instabilities that drive non-resonant quasilinear diffusion (NQD), thereby pumping energy from waves and the parallel motion of the particle into the perpendicular motion of the particle. It is shown that NQD can maintain the pitch angles for particles near the light-cylinder such that they radiate synchrotron radiation at MeV energies. Compared to conventional emission mechanisms (such as polar cap or outer gap models), the resulting spectrum has a relatively low upper cut-off from about a few to 100 MeV. Possible observational consequences of this mechanism are discussed.     

Effects of the Influence of a Wave on an Underwater Obstacle by a Stratified Flow of Finite Depth

Equations are obtained for a hydrodynamic load on an obstacle, which is modeled by a point dipole during its circulated flow of a two-layered liquid of finite depth. The correlations between the wave resistance and rising force and the rate of the flow and circulation are studied. Examples of numerical calculations for real marine conditions are given. It is shown that the account of circulation can significantly change the value of the hydrodynamic reaction, which impacts the dipole.

     

Internal Gravity Waves from an Oscillating Source in the Ocean

Izvestiya, Atmospheric and Oceanic Physics - The problem of the generation of internal gravity waves (IGWs) by a localized source of perturbations is considered. An oscillating source is located in...     

Radiogeochemical zoning and mapping of bottom sediments in the Eastern Gulf of Finland

A procedure is proposed for geochemical mapping of the water area bottom based on the subdivision of raw data into two components, i.e., systematic (regional) and random (local). The former is used to determine regional characteristic of the spatial radionuclide distributions in bottom sediments to be utilized to identify large radiogeochemical regions, while the latter is used to identify local anomalies and evaluate their characteristics. The systematic component of the radiogeochemical field is determined by trend analysis. Next, cluster analysis, i.e., hierarchic clusterization of the results of trend analysis followed by associative classification, is used for radiochemical zoning of the water area. After that, maps are constructed, showing contour lines of the local component of radiogeochemical fields, represented by deviations of the value in the given point from the trend. The result is a single map showing the radiogeochemical regions with contour lines of normalized anomalous activities of the radionuclides under study. The practical application of the method is illustrated by radiogeochemical mapping of the bed in the Eastern Gulf of Finland.     

Geochemistry and chemical evolution of saline lakes of Western Mongolia

This paper presents data on the major and trace element composition of saline lakes of western Mongolia. The main geochemical types of lakes distinguished in the study are soda-, chloride-, and sulfaterich lakes. Lake water equilibria with major carbonate, sulfate, chloride, and other rock-forming minerals were calculated. The results show that the major factors controlling the formation of each lake type include evaporation and water-rock interaction processes, and the latter factor plays a critical role in freshwater and soda lakes and only a minor role in chloride lakes. Special attention was given to the soda lakes and the factors controlling lake water chemistry.