Features of the volcanic seismicity regime on the example of the eruption of the Icelandic volcano Bárðarbunga in 2015
Features of the volcanic seismicity regime on the example of the eruption of the Icelandic volcano Bárðarbunga in 2015
E. M. Grekov
Volcanic seismicity has quite significant differences from tectonic seismicity, consisting in a different nature: here, instead of the mechanism of accumulation and release of stresses, there is destruction of the rock under the pressure of magma, low-frequency seismic waves arising from vibrations of a large volume of magma, as well as events of an explosive nature, when hot gases rush to the surface. Therefore, the study of the regime of volcanic seismicity is of particular interest. The seismic catalog of Iceland from 1995 to 2019 was analyzed in the study. The seismic regime of the Icelandic volcano Bárðarbunga (BAR) during the eruption is significantly different from the rest of the seismicity of the region. Through detailed reports from the Icelandic meteorological service, it was possible to establish that this difference was mainly due to two processes timed to the eruption: the collapse of the central caldera and the outflow of lava along a fissure swarm. Thus, it was possible to identify the nature of some of the events in the catalog as volcanic. As a result of the analysis of variations of b-value for the process of opening cracks under magma pressure, an anomaly of the b-value known from the literature was revealed, which is typical for so-called volcanic swarms. Thus, evidence was obtained in favor of the hypothesis that such anomalies, often preceding eruptions, are associated exactly with processes of this type. Also, using the Zaliapin– Ben-Zion nearest neighbor method, the grouping of events associated with the eruption was analyzed, and a significantly lower clustering of events was found compared to tectonic regimes, which is probably also due to the difference in the nature of these seismicities.
Show AbstractClassical experiments in school and university physics course
Classical experiments in school and university physics course
S. B. Ryzhikov$^2$, Yu. V. Ryzhikova$^1$
The problem of poor knowledge of experiments by schoolchildren confirming the main provisions of modern physics is considered. A physics course for grades 10-11 is proposed, the main core of which is the analysis of the change in three scientific paradigms: ancient, classical and modern. The course is not in the strict sense the history of physics, since it is developed not so much in the historical, so much in the logical aspect of the development of basic physical theories and does not always coincide with the chronology. Schoolchildren trace the development of knowledge about nature by studying experiments and theories arising from them. The material is fixed by solving the main types of problems. The course covers all sections of school physics studied in grades 10-11. A similar approach can also be used in a university course of general physics.
Show AbstractOn the organization of independent work of students within the course "General issues of teaching physical and mathematical disciplines"
On the organization of independent work of students within the course "General issues of teaching physical and mathematical disciplines"
T. A. Bushina
The experience of organizing independent work of students in the framework of the course "General issues of teaching physical and mathematical disciplines" is discussed. Examples of tasks that were offered to students for independent work are considered. The results of students' assignments are analyzed.
Show AbstractComputer teaching of physics: mechanical oscillations and waves, kinematics and dynamics of solid body
Computer teaching of physics: mechanical oscillations and waves, kinematics and dynamics of solid body
V. Yu. Ivanov$^1$, I. B. Ivanova$^2$, M. A. Terentyev$^3$
An example of the interactive teaching test is presented. As tasks in investigation we consider the classical tasks of general physics from mechanics. The structure of the teaching test is suggested. Some examples of teaching tips are given.
Show AbstractThe kinetic Boltzmann equation and the problem of the foundation of statistical mechanics
The kinetic Boltzmann equation and the problem of the foundation of statistical mechanics
P. N. Nikolaev
In the paper it is investigated the role of the Boltzmann kinetic equation in the process of formation of the problem of the foundation of statistical mechanics. The main aspects of this problem, as well as its current state, are presented. There is considered the activity of N.N. Bogolyubov on solving questions related to the foundation of statistical mechanics.
Show AbstractConjugation of crystal structures in alloys with martensitic transformations: the possibility of constructing a habitus plane by methods of differential geometry
Conjugation of crystal structures in alloys with martensitic transformations: the possibility of constructing a habitus plane by methods of differential geometry
A. G. Khundjua$^1$, B. A. Volodin$^2$, E. A. Brovkina$^3$
The phase transformation austenite-martensite can be considered as a homogeneous deformation, as a result of which a sphere of unit radius turns into an ellipsoid of deformation. A method for determining the position of the habitus plane based on the analysis of the curvature of the spatial curve of the intersection of the sphere and the deformation ellipsoid is proposed. The algorithm includes finding the coordinates of the point of minimum curvature by numerical methods, determining the position of the straightening plane at the specified point, and the coordinates of the center of curvature. The vector "center of curvature – the point of minimum curvature" defines the normal to the habitus plane. Comparison of the calculated values of the invariant plane indices with the experimental ones showed satisfactory agreement for a number of alloys. It is possible that the deviation of the calculated data from the experimental data for some alloys is due to the need to take into account the deviation from the orientation relationship in the process of martensite transformation.
Show AbstractHeat capacity of liquid
Heat capacity of liquid
P. N. Nikolaev
The heat capacity of a liquid is investigated in the paper. For this, the cell-cluster expansion for the free energy is used, taking into account three-particle clusters, inclusive. A system was chosen as the reference one, the potential of interaction between particles of which is a generalization of the Weeks-Chandler-Andersen potential for the case of effective consideration of not only the influence of nearest neighbors, but also of particles on other coordination spheres. The calculations performed for liquid argon showed good agreement between the theoretical results and experimental data.
Show AbstractMicrowave absorbing properties of modified solid solutions based on bismuth ferrite and lead ferroniobate with different thermodynamic background
Microwave absorbing properties of modified solid solutions based on bismuth ferrite and lead ferroniobate with different thermodynamic background
P. A. Astafev$^1$, K. M. Zhidel$^1$, J. A. Reizenkind$^1$, L. A. Shilkina$^1$, L. A. Reznichenko$^1$
In this work, the microwave absorbing and resonance properties of solid solutions based on BiFeO3 and Pb(Fe0.5Nb0.5)O3 modified with GeO2 have been studied. The choice of these systems is justified by the high microwave absorbing properties of the components separately and the prospects of their applications in microwave technology. A method for studying cylindrical material samples on a microstrip line using a network analyzer is briefly described. The measurements were carried out in the frequency range of 300 kHz - 26.5 GHz. For measurements, 3 series of samples were prepared using different process conditions, 3-5 samples in each. This was necessary for collecting statistics. Studies have shown that with an increase in the porosity of the material, its radio-absorbing properties increase. In addition, the height of cylindrical samples does not qualitatively affect their properties, which will greatly facilitate the preparation of new samples for research. Materials with a high concentration of lead ferroniobate have high radio absorbing properties. The results obtained will help in the development of materials with controlled microwave absorbing properties for applications as microwave absorbing coatings, microwave substrates, resonator and filter materials.
Show AbstractExample of using the method of analysis of wave cloud photography over the Сrimea mountains
Example of using the method of analysis of wave cloud photography over the Сrimea mountains
V. N. Kozhevnikov
The paper presents a method for visual analysis of photographs of a wave multilayer cloud. It is shown that the cloud is located in the crest of orographic waves above the main ridges of the Crimean mountains. It is shown that the spatial characteristics of the cloud correspond to the results of calculations based on the previously created nonlinear model of the flow around mountains.
Show AbstractThe method of equivalent substitutions, applied for the exact analytical solution of multilayer periodic structures with coupled wave thicknesses and specified amplitude-phase characteristics synthesis.
The method of equivalent substitutions, applied for the exact analytical solution of multilayer periodic structures with coupled wave thicknesses and specified amplitude-phase characteristics synthesis.
A. E. Zhitelev, A. V. Kozar
Based on the method of equivalent substitutions and the method of coupled wave thicknesses, a numerical analytical solution to the problem of calculations of the thickness values of the interference anti-reflective structure ("π structure") for an arbitrary number of layers is obtained. Exact algorithm is obtained that make it possible to synthesize antireflection structures providing a predefined reflection coefficient on the entire continuous set of values from 0 to 1 for any real values of the refractive indices of both matched media and materials of layers of such structures. The correctness of the obtained algorithm and the efficiency of the method are confirmed by a numerical experiment.
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