Study of the albedo of marble and sand
Study of the albedo of marble and sand
B. M. Ibrahim$^1$, Yu. P. Pyt'ev$^2$, A. A. Samah$^1$, O. V. Falomkina$^2$
In this paper, the intensity of solar radiation incident and reflected from the surfaces of marble and sand is studied in detail. The albedo values of these surfaces are calculated on the basis of radiation intensity measurements performed using a luxmeter. The measurements were carried out for marble and sand surfaces during two days of the summer months at two points in the vicinity of Baniyas on the Mediterranean coast in the province of Tartus, in Syria: in the town of Alqurdiye and at the station "Baniyas". The albedo values are calculated based on the measurement results. The results are compared, graphical curves are constructed that reflect the changes in albedo depending on time.
Show AbstractCentrality dependence of particle emission in nucleus-nucleus collisions at the nucleon and quark levels
Centrality dependence of particle emission in nucleus-nucleus collisions at the nucleon and quark levels
G. O. Ambaryan$^3$, V. L. Korotkikh$^1$, G. H. Eyyubova$^2$
A theoretical analysis of the particle multiplicity as a function of centrality is made with respect to particle emission sources (wounded nucleons, quarks) in a wide energy range from RHIC to LHC. The Monte Carlo Glauber model is used for heavy ion collisions. It is shown that scaling in terms of the number of wounded quarks is fulfilled at all energies. This effect is associated with an increase of the wounded quarks pairs in the transverse plane with a decrease of the colliding nuclei impact parameter. A wounded quark emits the same number of particles regardless of the colliding nuclei impact parameter.
Show AbstractAcoustic field of a source moving perpendicular and along the interface with a sharp impedance drop
Acoustic field of a source moving perpendicular and along the interface with a sharp impedance drop
Yu. M. Zaslavsky$^1$, V. Yu. Zaslavsky$^{1,2}$
The acoustic field generated by a pulsating source moving in the atmosphere along and perpendicular to the water-atmosphere interface at a subsonic speed is investigated. Calculated relationships are derived for the amplitude, frequency, and duration of a sound pulse recorded in both media in the vicinity of the interface. The spatial distribution of the amplitude of the acoustic field in the atmosphere and in the liquid is presented in the form of a two-dimensional relief to demonstrate its features and dependence on the speed and direction of motion of the sound source. The relationship between the characteristics of acoustic radiation and the average depth in the water area is analyzed.
Show AbstractLightlike singular hypersurfaces in quadratic gravity
Lightlike singular hypersurfaces in quadratic gravity
I. D. Ivanova
For a singular hypersurface of arbitrary type in quadratic gravity equations of motion were obtained using the principle of least action. The equations containing the components of the surface energy-momentum tensor corresponding to the “external pressure” and “external flow” together with the Lichnerowicz conditions are necessary to find the hypersurface itself, while the rest of the equations define “arbitrary” functions that arise due to the implicit presence of derivative of the delta function. It turned out that there are no double layers or thin shells for the Gauss-Bonnet quadratic term. It was demonstrated that there is no “external pressure” for null singular hypersurfaces. For spherically symmetric lightlike singular hypersurfaces the “external flux” is additionally equal to zero; therefore, such hypersurfaces can only be thin shells. In this case the system of equations of motion is reduced to one, which is expressed through the invariants of spherical geometry along with the Lichnerowicz conditions.
Show AbstractMolecular dynamic modeling of thermophysical properties of gold.
Molecular dynamic modeling of thermophysical properties of gold.
A. A. Aleksashkina
Gold thermodynamic properties were examined by molecular dynamics with use of the embedded atom model. The LAMMPS package was used. Equilibrium melting temperature and specific heat as function of pressure were determined in range from 0 to 100 kbar. Density and specific heat as function of temperature were determined in range from 300 to 5000 K that included melting region. The modeling results were consistent with those from other authors both experimental and determined with other methods. These dependences and quantities can be used as input data for the continuum model of pulsed laser heating of matter.
Show AbstractResearch of Resonance Regimes of Axisymmetrical Oversized Open-System Relativistic Diffraction Generator
Research of Resonance Regimes of Axisymmetrical Oversized Open-System Relativistic Diffraction Generator
S. V. Khudyakov, O. V. Gallyamova
The results of modeling the interaction of a tubular electron beam and a field in an oversized axisymmetric relativistic diffraction generator on a periodic sequence of tori are presented. A numerical analysis of the generator response to the effect of an electron beam modulated at a given frequency in resonant modes is carried out. The diffraction boundary value problem was solved by the method of integral equations. The influence of the structure parameters by resonant frequencies upon the distributions of the components of the electromagnetic field in the space of interaction between the flow and the field were studied.
Show AbstractNumerical solution of the Korteweg-de Vries equation on a moving grid using two-layer difference schemes
Numerical solution of the Korteweg-de Vries equation on a moving grid using two-layer difference schemes
E. N. Bykovskaya
This paper presents the results of a numerical and analytical study of 2-layer explicit and implicit difference schemes for the KdV equation. On Eulerian computational grids, a satisfactory numerical solution was obtained only when using an explicit-implicit difference scheme of the Crank-Nichols type of the second order of approximation in time t and spatial x variables. A completely implicit 2-layer scheme of the 1st order in time t and 2nd in the space x, although it is absolutely stable, but the presence of a high schematic viscosity leads to a significant distortion of the solution. The use of moving grids with dynamic adaptation made it possible to obtain high-precision numerical solutions not only for Crank-Nichols-type schemes, but also for a family of completely implicit 2-layer schemes of the 1st order in time t and 2nd in space x. An important advantage of the considered schemes is their simplicity and transparency of the basic mathematical constructions.
Show AbstractThe computer model of the initial stages of aggregation of mixamoeba Dictyostelium discoideum
The computer model of the initial stages of aggregation of mixamoeba Dictyostelium discoideum
I. V. Kruchinin, L. V. Yakovenko
Dictyostelium discoideum (DD) is a species of soil-dwelling amoeba belonging to the phylum Amoebozoa, infraphylum Mycetozoa. The life cycle of this organism, commonly referred to as a slime mold, consists of unicellular and multicellular stages: when food is scarce, myxamoebae stop feeding, move to each other, collide and stick together, forming intermediate clusters, which then aggregate to form a so-called slug, which includes up to 105 cells. This process is controlled by interacting intracellular and extracellular signaling systems. In this paper, we propose a model of the initial stages of myxamoeba aggregation based on cellular automata. The model includes four interconnected systems of cellular automata, one of which, that describes the movement of myxamoebae, consists of movable cellular automata. The other three systems model the release and diffusion of three main signal components forming the chemotactic field that determines the behavior of myxamoebae. Numerical experiments have shown that the model describes dynamics of the mixamoeba distribution on the surface corresponding to the real DD aggregation process. In particular, it was shown that at the first stages of aggregation, cell clustering always occurs, after which clusters merge to form continuous cell flows moving to the center of aggregation.
Show AbstractAcoustical studies of biovessels
Acoustical studies of biovessels
B. N. Klochkov
Analyse of distributed oscillations of soft elastic vessel with blood flow in it is supplied and conditions of wave effects existence are considered. Dispersion characteristics of acoustic processes are given. The possibility of the existence of fixed structures is shown, conditions of instability rise are described.
Show AbstractInitial state hot gluonic spots in heavy-ion collisions
Initial state hot gluonic spots in heavy-ion collisions
G. H. eyyubova$^1$, V. L. Korotkikh$^2$, A. M. Snigirev$^3$, E. E. Zabrodin$^4$
In this review a detailed study of the properties of elliptical and triangular eccentricities in the initial state of heavy ion collisions is presented. We use the model of random energy source distribution in the transverse plane within effective theory of color condensation. It is shown that the elliptical flow is closely related with the geometry of the ions collision. A triangular flow has a purely fluctuation nature and its dependence on centrality is determined exclusively overlap area.
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