Testing ionospheric model NeQuick 2 using satellite measurements of electron concentration
Testing ionospheric model NeQuick 2 using satellite measurements of electron concentration
B. A. Matiushin$^1$, V. I. Zakharov$^{1,2,3}$, N. A. Suhreva$^{1,4}$, O. V. Shestakov$^5$
We present the results of the study of systematic errors of the ionospheric model NeQuick 2, the verification of which was carried out on the data of satellite measurements of electron concentration of the Swarm mission for 2014. The measurements performed by Langmuir probes installed on the spacecraft of this mission during the period of solar activity maximum were used in this work. The conducted research made it possible to determine the average modeling errors in different latitude zones and geomagnetic conditions and to obtain the spatial distributions of systematic deviations of the model from the measurement data. The characteristic values of deviations are up to 80%, and in the conditions of geomagnetic disturbance the error in certain geographical areas increases up to 300%. The zones of increasing systematic deviations are observed in the high latitudes of the southern hemisphere. The results of the work can be useful for the operation of radio facilities and various applications, for example, to improve navigation and communication and to refine models of the ionosphere.
Show AbstractRate coefficients for the vibrationally inelastic transitions of the O($^{3}$P$_g$)+O$_{2}$($^{3}\Sigma_{g}^{-}$) system on the O$_3$ ground electronic state potential energy surface at 100-1000K
Rate coefficients for the vibrationally inelastic transitions of the O($^{3}$P$_g$)+O$_{2}$($^{3}\Sigma_{g}^{-}$) system on the O$_3$ ground electronic state potential energy surface at 100-1000K
A. K. Kurnosov$^{1,2}$, A. N. Kropotkin$^1$, A. A. Chukalovsky$^1$, A. T. Rakhimov$^1$, T. V. Rakhimova$^1$, G. G. Balint-Kurti$^3$, A. P. Palov$^1$
The v→v rate coefficients for the vibrationally inelastic collisions of O atoms with O$_2$ molecules are presented for vibrational quantum numbers v from 0 to 8 and temperatures from 100K to 1000K. State-to-state rate coefficients were computed theoretically using an ab initio O-O$_2$ interaction potential for the ground state of O$_3$ and the final rate coefficients are obtained by summing the state-to-state rate constants over final rotational states and averaging over an equilibrium Boltzmann distribution of relative translational energies and initial rotational states at temperatures of interest in plasma processes. The rate constants obtained are compared with available quasi-classical calculations. The coefficients obtained are required in the modeling of many industrial processes such as plasma etching, surface treatment, plasma sterilization, and medicine.
Show AbstractNumerical solution of the multi-constant equations of state with high accuracy
Numerical solution of the multi-constant equations of state with high accuracy
E. V. Koldoba
In some pressure and temperature ranges, high-precision thermal equations of state have many roots, and only one of them is the desired solution to the problem. The paper considers methods for setting initial values ??to find the desired root of the equation. A method for checking the found root has been developed, which allows one to exclude non-physical roots. The proposed approach allows one to construct a robastness algorithm for the numerical solution of transcendental equations of state.
Show AbstractTheory of grazing incidence X-ray scattering by nanocomposite structures
Theory of grazing incidence X-ray scattering by nanocomposite structures
O. Yu. Yurakova$^{1,2,3}$, R. A. Baulin$^3$, M. A. Andreeva$^3$
The formula describing the scattering on a one-dimensional paracrystals (Hosemann R. // Zeitschrift für Physik. 128. 465. (1950)) is generalized for the case of X-ray scattering in grazing geometry (GISAXS – Grazing Incidence Small Angle X-ray Scattering) on a radial paracrystals, taking into account the refraction and attenuation of radiation by the reflecting and scattering medium. The formula is applicable to the description of GISAXS scattering maps on nanocomposite quasi-amorphous structures.
Show AbstractDeep learning ghost polarimetry of two-dimensional objects with amplitude anisotropy
Deep learning ghost polarimetry of two-dimensional objects with amplitude anisotropy
D. A. Chernousov, D. P. Agapov
The paper discusses the possibilities of deep learning in solving the inverse problem of computational ghost polarimetry. For the first time it is shown that the spatial distribution of the polarization properties of objects with linear amplitude anisotropy is restored using a neural network trained on model data. The spatial distribution of the parameters of linear amplitude anisotropy is determined with an accuracy of 7.8 and 15.6\% for azimuth of anisotropy and value of anisotropy, respectively.
Show AbstractPeriodic internal transition layers in the reaction-diffusion problem in the case of a weak reaction discontinuity
Periodic internal transition layers in the reaction-diffusion problem in the case of a weak reaction discontinuity
E. I. Nikulin, V. T. Volkov, D. A. Karmanov
For a singularly perturbed reaction-diffusion equation with periodic coefficients, the structure of the inner transition layer in the case of a balanced reaction with a weak discontinuity is investigated. The existence of periodic solutions with an internal transition layers is proved, the question of their stability is investigated, and asymptotic approximations of solutions of this type are obtained. It is shown that in the case of reaction balance, the presence of even a weak (asymptotically small) reaction gap can lead to the formation of several contrasting structures of finite size, both stable and unstable.
Show AbstractLocalized electronic states of graphene on the terrace-stepped substrate
Localized electronic states of graphene on the terrace-stepped substrate
G. A. Krasyukov$^{1,2}$, O. V. Pavlovsky$^{1,2}$
The localized fermionic states arising in an effective field theory model of graphene on the substrate generating a spatially inhomogeneous mass gap were studied. It was shown that in case of terraced-stepped structure of the substrate inhomogeneity in which the chiral mass has the opposite sign on different terraces, both massless and massive fermionic states are generated. The mass spectrum of such states depends on the size of the mass gap generated by the substrate, as well as the width of the terraces, the number of terraces in the substrate structure, and the width of the transition step.
Show AbstractNumerical simulation of retrograde condensation of binary hydrocarbon mixtures using direct energy minimisation
Numerical simulation of retrograde condensation of binary hydrocarbon mixtures using direct energy minimisation
A. V. Isaeva
In this paper, retrograde condensation is considered using binary mixtures of hydrocarbons as an example. The possibility of numerical simulation of this phenomenon using the direct energy minimisation is demonstrated. To verify the calculations performed, similar modelling is carried out using the “classical” iterative algorithm for calculating vapour-liquid equilibria of multicomponent mixtures of hydrocarbons. A comparison of the simulation results, as well as the data of physical experiments, allows us to conclude that the method of direct energy minimisation is promising for calculating phase transitions of hydrocarbon mixtures.
Show AbstractMagnetoactive polymer composites: achievements and development prospects
Magnetoactive polymer composites: achievements and development prospects
T. A. Nadzharyan$^{1,2}$, S. A. Kostrov$^{1,2}$, E. Yu. Kramarenko$^{1,2}$
Magnetoactive polymer composites are polymer matrices containing magnetic micro- and/or nanoparticles. They belong to the class of “smart” materials and are currently of great fundamental and practical interest. This article focuses on magnetoactive elastomers (MAE), the research of which has been carried out at the faculty of physics of Moscow State University since the late 90s of the 20th century. A definition of MAE and the properties of its main components – the polymer matrix and magnetic particles – are given. A review of the physical phenomena exhibited by these materials when external magnetic fields are applied is provided. The influence of the material composition on its magnetic response is discussed in detail, with emphasis on the magneto-mechanical properties that are most important for practical applications. The results of recent studies related to the synthesis of new matrices for MAE, the influence of the shape and distribution of magnetic particles in the polymer matrix, as well as modern theoretical approaches to describing the behavior of MAEs in an external magnetic field are analyzed. In conclusion, the prospects for further development of the field related to the development of magnetically active polymer materials and the prospects for their practical application are discussed.
Show AbstractStudy of the domain walls dynamics in transparent ferromagnets using high-speed photography
Study of the domain walls dynamics in transparent ferromagnets using high-speed photography
T. B. Shapaeva
The work is devoted to studying the dynamics of domain walls and magnetic vortices arising in the domain walls of transparent ferromagnets. First, a review of methods for studying the magnetization reversal dynamics is given. Of the variety of these methods, the method of high-speed photography based on the Faraday effect was chosen for a more detailed consideration, since it allows one to observe the dynamic domain structure and determine the domain wall velocity with high accuracy. For optimal use of the chosen method, the work describes experimental studies of the magnetization reversal dynamics in materials with a high magneto-optical quality factor: films of Bi-containing ferrite garnet, GdFeCo and yttrium orthoferrite. The choice of these materials is due to the fact that they exhibit high velocity of domain wall and magnetic vortices, the value of which can reach 1.2 km/s in GdFeCo, about 10 km/s in garnet ferrites and up to 20 km/s in yttrium orthoferrite. In addition, ferrite garnets exhibit a periodic labyrinthine domain structure, which makes it possible to use magneto-optical diffraction to study the domain wall dynamics with high spatial resolution.
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