Southern Scientific Center
Author list of organization
List of articles written by the authors of the organization
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TO THE RESEARCH METHODS OF FAULTS UNDER THE VIBRATION IMPACTS
01.00.00 Physical-mathematical sciences
Description
We propose an approach to the modeling of stressstrain state of lithospheric structures near faults by modeling them as Kirchhoff plates on threedimensional elastic foundation. We describe an efficient method of solving problems for plates with rectilinear fractures, based on the transformation of the differential operator, which allows us to analyze the solutions obtained for different contact conditions in the area of the fracture. The method is presented on the example of the vibration problem of two elongated plates on the surface of the elastic layer under the effect of concentrated surface load. The results of numerical implementation of the developed algorithm make it possible to identify the influence of the substrate properties, characteristics of the plates and the nature of their border interactions on the picture of wave process in the test structure. At the same time obtained configurations of the harmonic signal passage through the fracture can serve as an indicator of its type. The proposed approach should be used to determine the presence and type of fractures based on measurements of signals from vibration sources in cases when geophysical environment can be modeled by the previously described structure. The problems of studying objects we reviewed in this paper also occur in various areas of technology, and, therefore we can apply the proposed method for their solution
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01.00.00 Physical-mathematical sciences
Description
The article is dedicated to a numerical investigation of a plane problem of the oscillation amplitude of a buried source, depending on the frequency and motion speed in various isotropic media. Three types of the medium are considered: a two-layer package with a rigidly fixed base, a two-layer package with a mechanically free base, a half-space. The source, in the form of a stress jump simulating a rigid inclusion of small dimensions, moves in the interface plane at a constant speed. Homogeneous boundary value problems are considered in a moving coordinate system associated with a source. The solution method is based on the usage of integral Fourier transforms, the method of direct contour integration and algorithms for constructing symbols of Green's matrices. The method of direct contour integration significantly simplifies calculations in comparison with the traditional approaches to the calculation of Fourier integrals. We have presented calculations of nine amplitude-frequency and amplitude-velocity characteristics for different combinations of medium and source types, that give an exhaustive qualitative and quantitative description of the solutions for boundary value problems in a wide range of velocities and frequencies. Comparative analysis of calculations showed a primary influence of the type of an elastic medium on the investigated characteristics, as well as the large influence of the source type. Which, in turn, revealed some substantial connections between the boundary value problems with a moving source and the corresponding problems with a stationary source
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Description
This article is devoted to the study of small mammal communities (species composition, daily activity and spatial distribution) in the agrocoenosis. The fields of winter crops that were surrounded by similar fields or by winter crops with meadow vegetation were researched. The Mus musculus became the dominant species in the winter crops agrocoenosis. The R. Sylvaemus living near the border with field-protective forest belts (and 25 meters field around) are subdominant group. Marked single finds Mus musculus in the forest and R. Sylvaemus in the field (at a distance before 50 meters). It is shown that the presence of meadow vegetation increases the species diversity of mice in the agrocoenosis. In the middle of this field a subdominantion group is Microtus arvalis s.l. and Cricetulus migratorius. The both species prefer a neighborhood with meadow vegetation. The method of recapture, followed by labeling with animals, made it possible to fix the movement for a distance of about 400 m. during the night (maximum values were males Mus musculus). The activity of small mammals in the winter crops was timed to coincide with the day-night cycles, with high activity from 01:00 to 04:00 am, and minimum activity after 09:00 hours of the morning before 08:00 pm
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