Technique of the identification, quantification and measurement of carbon short-fibers using the instance segmentation

The present work shows the use of a convolutional neural network architecture that uses the computer vision technique of segmentation of instances for identification, quantification and measurement of short carbon fibers

Mathematical modeling of heat transfer between the plant seedling and the environment during a radiation frost

The power of the internal heat source sufficient to maintain a positive temperature of plants during one of the possible form of cold stress - radiation frost was determined with the help of numerical simulation.The simulation of unsteady heat transfer in the soil-plant-air system in the conditions of radiation frost showed that the the ground part of plants is cooling most rapidly, and this process is partially slowed down by the natural-convection heat transfer with warmer air. If the frost is not continuous, the radiative cooling is the main danger for plant. The necessary power of heat-production inside plant that allows it to avoid hypothermia depends both on natural conditions and the size of the plant. For plants with a typical diameter of the stem about 2 mm this heat-production should be from 50 to 100 W / kg. Within 2 hours a total amount of heat about 0.5 MJ / kg in the plant should be allocated. Larger plants will have a smaller surface to mass ratio, and the maintaining of it's temperature will require a lower cost of nutrients per unit, accordingly. Modeling of the influence of plant surface trichomes presence on the process of its cooling showed that the role of trichomes in the protection of plants from hypothermia during radiation frost usually is negative due to the fact that the presence of trichomes increases the radiative heat transfer from the plant and the impediment in air movement near the plant reduces heat flux entering the plant from a warmer air. But in cases where the intensity of heat generation within the plant is sufficient for the maintenance of the plant temperature higher than the air temperature, the presence of trichomes impairs heat transfer from plant to air, and therefore contributes to a better heating of plants

Integrated fiber-based transverse mode converter

A transverse mode converter based on a binary microrelief implemented directly on the end-face of a few-mode fiber was numerically investigated. The results of numerical simulation demonstrated the converter to form LP-11 and LP-21 modes with high efficiency, providing a more-than 92 % mode purity. Transformations of modes excited by a fiber microbending were also numerically investigated. The excited beams were shown to save their mode purity even in a strong bending as the arising parasitical modes were mostly unguided by the fiber. The resulting beam power and mode content were also demonstrated to depend on the beam and bending mutual orientation for beams with strong rotational symmetry.This work was partly supported by the Ministry of Education and Science of the Russian Federation (project 16.7894.2017/6.7)

Study of the features of modeling microwave vacuum evaporation

Evaporation is the most common concentration method. The complete reuse of latent thermal energy by means of mechanical recompression is the most technologically efficient method of operation of evaporators. This method requires much less electricity to compress the secondary steam compared to the heat of the secondary steam. In this scheme, the energy released during steam condensation can be used to heat the initial solution, which makes it possible to achieve the reuse of thermal energy at the level of 95%. Thus, during the the evaporation process implementation, when energy is supplied by electromagnetic microwave radiation, conditions are created for the initiation of vaporization in the entire liquid volume, which will avoid product overheating in the thermal boundary layer due to the absence of such. This allows to get a product of high concentration, without the taste of “cooking”, without changing color and flavor. When modeling these processes, boundary conditions of the third kind are replaced by boundary conditions of the second kind. Considering the proposed hypothesis, a process model can be considered, assuming the presence of internal energy sources evenly distributed in the product volume. This opens up the possibility of using deterministic mathematical models, provided that the corresponding initial and boundary conditions are determined. As a result of generalization of the experimental modeling results, a model in a criterion form has been obtained, which allows calculating a microwave vacuum-evaporation apparatus of periodic action for solutions containing polar molecules. The model in the range of dimensionless pressure 2 ≤ P ≤ 22, and at the level of dimensionless heat of the phase transition 1 ≤ R ≤ 4.56 provides accuracy with a maximum deviation of ± 8%

Conforming identification of the fundamental matrix in image matching problem

The article considers the conforming identification of the fundamental matrix in the image matching problem. The method consists in the division of the initial overdetermined system into lesser dimensional subsystems. On these subsystems, a set of solutions is obtained, from which a subset of the most conforming solutions is defined. Then, on this subset the resulting solution is deduced. Since these subsystems are formed by all possible combinations of rows in the initial system, this method demonstrates high accuracy and stability, although it is computationally complex. A comparison with the methods of least squares, least absolute deviations, and the RANSAC method is drawn.This research was supported by the RF Ministry of Education and Science (Project # 2.7891.2017/6.7)

Gravitational excitons from extra dimensions

Inhomogeneous multidimensional cosmological models with a higher dimensional space-time manifold are investigated under dimensional reduction. In the Einstein conformal frame, small excitations of the scale factors of the internal spaces near minima of an effective potential have a form of massive scalar fields in the external space-time. Parameters of models which ensure minima of the effective potentials are obtained for particular cases and masses of gravitational excitons are estimated.Comment: Revised version --- 12 references added, Introduction enlarged, 20 pages, LaTeX, to appear in Phys.Rev.D56 (15.11.97

A new approach for producing of film structures based on Si1-xGex

In this work, we propose a new, previously unpresented in the literature, approach to the formation of Si1-xGex films. This approach includes electrochemical processes of the formation of porous silicon, electrochemical deposition of low-melting metals and Ge. Post-heat treatment is made possible to synthesize film structures based on Si1-xGex solid solutions. Using this approach an alloy of the composition Si0.4Ge0.6 has been obtained at a lower formation temperature than predicted by the phase diagram for the Si-Ge system

Systems of Hess-Appel'rot type

We construct higher-dimensional generalizations of the classical Hess-Appel'rot rigid body system. We give a Lax pair with a spectral parameter leading to an algebro-geometric integration of this new class of systems, which is closely related to the integration of the Lagrange bitop performed by us recently and uses Mumford relation for theta divisors of double unramified coverings. Based on the basic properties satisfied by such a class of systems related to bi-Poisson structure, quasi-homogeneity, and conditions on the Kowalevski exponents, we suggest an axiomatic approach leading to what we call the "class of systems of Hess-Appel'rot type".Comment: 40 pages. Comm. Math. Phys. (to appear