Elastic properties of mono- and polydisperse two-dimensional crystals of hard--core repulsive Yukawa particles

Monte Carlo simulations of mono-- and polydisperse two--dimensional crystals are reported. The particles in the studied system, interacting through hard--core repulsive Yukawa potential, form a solid phase of hexagonal lattice. The elastic properties of crystalline Yukawa systems are determined in the $NpT$ ensemble with variable shape of the periodic box. Effects of the Debye screening length ($\kappa^{-1}$), contact value of the potential ($\epsilon$), and the size polydispersity of particles on elastic properties of the system are studied. The simulations show that the polydispersity of particles strongly influences the elastic properties of the studied system, especially on the shear modulus. It is also found that the elastic moduli increase with density and their growth rate depends on the screening length. Shorter screening length leads to faster increase of elastic moduli with density and decrease of the Poisson's ratio. In contrast to its three-dimensional version, the studied system is non-auxetic, i.e. shows positive Poisson's ratio

Large thermoelectric figure of merit for 3D topological Anderson insulators via line dislocation engineering

We study the thermoelectric properties of three-dimensional topological Anderson insulators with line dislocations. We show that at high densities of dislocations the thermoelectric figure of merit ZT can be dominated by one-dimensional topologically-protected conducting states channeled through the lattice screw dislocations in the topological insulator materials with a non-zero time-reversal-invariant momentum such as Bi_{1-x}Sb_x. When the chemical potential does not exceed much the mobility edge the ZT at room temperatures can reach large values, much higher than unity for reasonable parameters, hence making this system a strong candidate for applications in heat management of nano-devices.Comment: 4 pages, 3 figure

Laser Conoscopy Study of Optical Anomalies in Uniaxial Crystals

New experimental possibilities of detecting fine optical anomalies in uniaxial crystals are demonstrated on a level with numerical estimation of refractive index and mechanical stress variations that cause distortions of the optical indicatrix. New possibilities are due to the use of an exact equation for isochromes derived for uniaxial crystals without mathematical simplifications commonly used by other authors. It allows one to calculate and graphically reproduce the theoretical form of isochromes of any orders in the conoscopic picture of an ideal crystal with known principal refractive indices, the thickness and orientation of the crystal surfaces, and also the wavelength of the radiation and the parameters of the optical circuit. A computer comparison of the theoretical image with an experimental conoscopic picture of a real crystal, fixed by a color digital camera on a semitransparent screen, is performed. The data on the variations of refractive indices and mechanical stresses in the crystal are retrieved from the mathematical processing of differences in the conoscopic images. The applications of the proposed method for the analysis of optical homogeneity of paratellurite and lithium niobate single crystals are presented. Keywords: method of conoscopy, isochromes, piezo-optic effec

Chirality inversion and radius blow-up of a N\'eel-type skyrmion by a Pearl vortex

We develop a theory for the coaxial configuration of a N\'eel-type skyrmion and a Pearl vortex in thin superconductor-chiral ferromagnetic heterostructures. Using direct numerical solution of the Euler-Lagrange equation and micromagnetic simulations we demonstrate that the inhomogeneous magnetic field of the Pearl vortex significantly modifies the skyrmion profile with respect to the one in the absence of the vortex. We discover drastic enlargement of the skyrmion's radius and inversion of the skyrmion's chirality. To unravel physics behind these effects we invent novel two-parameter ansatz for the magnetization profile of the skyrmion in the presence of the vortex. Chirality inversion and radius blow-up are controlled not only by the material parameters of the heterostructure but also by the thickness of the superconductor. Our findings can have implications for Majorana modes localized at skyrmion-vortex pairs.Comment: 6 pages, 2 figures; 1 video file and its description (as ancillary files

Concept of creation 3D-virtual technology-oriented of business simulators for industrial complexes

Предложена концепция создания и базовые основы построения технологически ориентированных бизнес-симуляторов для промышленных комплексов. Функционально симуляторы представлены в виде многопользовательских и многофункциональных распределенных виртуальных обучающих модулей. В них одновременно реализуются несколько уровней взаимосвязанных задач обучения основам технологии производства, экономики предприятия и эффективности инвестиций.Proposed the concept of creation and basic fundamentals of building technologyoriented business simulators for industrial complexes. Functionally, the simulators are presented in the form of multi-user and multi-distributed virtual training modules. They both realized several levels of interrelated tasks of learning the basics of production technology, economy of the enterprise and efficiency of investments

Building Heat-insulating Materials Based on the Products of the Transesterification of Polyethylene Terephthalate and Dibutyltin Dilaurate

In this paper, we offered a technological basis for production of heat-insulating polyurethane materials based on the aromatic polyester - the product of transesterification of polyethylene terephthalate and corrective additive - dibutyltin dilaurate. Also, we presented the formulation and properties of the developed polyurethanes

Asymmetric Domain Nucleation and Unusual Magnetization Reversal in Ultrathin Co Films with Perpendicular Anisotropy

We report unexpected phenomena during magnetization reversal in ultrathin Co films and Co/Pt multilayers with perpendicular anisotropy. Using magneto-optical Kerr microscopy and magnetic force microscopy we have observed asymmetrical nucleation centers where the reversal begins for one direction of the field only and is characterized by an acute asymmetry of domain-wall mobility. We have also observed magnetic domains with a continuously varying average magnetization, which can be explained in terms of the coexistence of three magnetic phases: up, down, and striped

Feasibility of development and experience establishment of a process simulator and virtual laboratory

В докладе приведены результаты анализа вопроса по актуальности и целесообразности разработки и применения технологических симуляторов и виртуальных лабораторий для эффективного обучения и формирования профессиональных навыков. Выделены направления применения и технико-экономические эффекты от внедрения. Опыт разработки технологических симуляторов рассматривается на примерах создания 3D-симулятора для отработки аварийных ситуаций медеплавильного цеха и виртуального учебно-исследовательского комплекса лабораторных работ по теплофизике.The report provides an analysis of the question on the relevance and feasibility of the development and use of simulation technology and virtual labs for effective learning and the formation of professional skills. Isolated areas of use and technical economic effects of the introduction. Experience in developing technological simulators regarded by creating a simulator for testing emergency of copper melting shop and virtual educational research laboratory complex papers on thermal physics