Velocity selection problem for combined motion of melting and solidification fronts

We discuss a free boundary problem for two moving solid-liquid interfaces that strongly interact via the diffusion field in the liquid layer between them. This problem arises in the context of liquid film migration (LFM) during the partial melting of solid alloys. In the LFM mechanism the system chooses a more efficient kinetic path which is controlled by diffusion in the liquid film, whereas the process with only one melting front would be controlled by the very slow diffusion in the mother solid phase. The relatively weak coherency strain energy is the effective driving force for LFM. As in the classical dendritic growth problems, also in this case an exact family of steady-state solutions with two parabolic fronts and an arbitrary velocity exists if capillary effects are neglected. We develop a velocity selection theory for this problem, including anisotropic surface tension effects. The strong diffusion interaction and coherency strain effects in the solid near the melting front lead to substantial changes compared to classical dendritic growth.Comment: submitted to PR

Temperature field around a spherical, cylindrical, and needle-shaped crystal, growing in a pre-cooled melt

The growth of a single crystal in a precooled melt was examined. The conditions under which this occurs are described. It is found that the movement of the crystallization front is proportional to the root of time. The problem is solved based on the presented considerations

Astrometrical Observations of the Near-Earth Asteroid 308635 (2005 YU55) in Nikolaev

International audienceA near-Earth asteroid 308635 (2005 YU55) was discovered by Spacewatch group at Kitt Peak Observatory (691) on Decembre 28, 2005. The asteroid belongs to the Apollo group, moreover it is a potentially hazardous asteroid presented in the critical list of the Minor Planet Center, the minimum orbit intersection distance of the asteroid with the Earth is 0.000454 a.u. As to the radar observations in 2010, the diameter of the asteroid is 0.4 km. Due to the high eccentricity of its orbit, the asteroid has close encounters not only with the Earth and the Moon, but also with Venus and Mars, so the orbit of this asteroid can be a subject of special interest for studying different gravitational perturbations

Urban planning culture within Sochi in the first half of ХХ century

The article considers urban planning culture within Sochi in the first half of the ХХ century. Special attention is attached to styles and developmental milestones of Sochi architectural look

Kuban and Black sea region authorities and society in 1920–1922: soviet government perception by local population

The article considers relations of authorities and society within Kuban and Black Sea Province at the end of Civil War in Russia (1920–1922)

Magnetic Flux Leakage Method: Large-Scale Approximation

We consider the application of the magnetic flux leakage (MFL) method to the detection of defects in ferromagnetic (steel) tubulars. The problem setup corresponds to the cases where the distance from the casing and the point where the magnetic field is measured is small compared to the curvature radius of the undamaged casing and the scale of inhomogeneity of the magnetic field in the defect-free case. Mathematically this corresponds to the planar ferromagnetic layer in a uniform magnetic field oriented along this layer. Defects in the layer surface result in a strong deformation of the magnetic field, which provides opportunities for the reconstruction of the surface profile from measurements of the magnetic field. We deal with large-scale defects whose depth is small compared to their longitudinal sizes---these being typical of corrosive damage. Within the framework of large-scale approximation, analytical relations between the casing thickness profile and the measured magnetic field can be derived.Comment: 12 pages, 3 figure

‘Sochi’ resort development and functioning in 1935–1950

The article is focused on the history of ‘Sochi’ rest home establishment and functioning. Later ‘Sochi’ was turned into resort and was included into Sochi group of resorts, first under the supervision of USSR Central Executive Committee and in 1938 it passed into jurisdiction of USSR Council of People's Commissars – USSR Council of Ministers