Aim. Study of the model of nucleus-sized nanocrystal and identification of its properties and patterns.

Methodology. A model was developed and numerical calculations were carried out on the example of the binary semiconductor GaAs, which showed that during the spontaneous formation of a nanocrystal, the crystal lattice with an elementary cell size of 0.4 – 0.5 nm is formed, which is greater than the length of the bond of both gallium and arsenic atoms when they are possible combined in the molecule (the sum of atomic radii is 0.273 nm) and less than the lattice constant of gallium arsenide (0.565 nm). The size of the nanocrystal, calculated as the cubic root of the product of the number of atoms and the volume of the unit cell, is 0.6 – 1.4 nm. These values correspond quite accurately to the estimation of the de Broglie wavelength for the electron of the bulk crystal. The bandgap decreases with the number of atoms, varying from the electron affinity of the material (4.1 eV) to the bandgap of the bulk crystal (1.42 eV).

Results. If the size of the nanocrystal is more than the minimum (unit cell), the physical models and approaches used for the bulk crystal are applicable to the nanocrystal.

Research implications. A model of properties of a nanosized system GaAs doped with Zn has been developed that provides prediction of new functionality of these materials.

Aim. Describe the teleportation of information using the model of entangled solitons.

Methodology. The research method is a model of quantum teleportation of the properties of quantum particles, such as photons, based on the description of classical entangled soletons.

Results. The considered model demonstrates the transfer of solitons properties, similar to the transfer of quantum particles properties, called quantum teleportation.

Research implications. The theoretical and practical significance lies in the possibility of considering quantum phenomena on such classical objects as soletons. 

Aim. The aim is to generalize the available analytical and numerical results of the study of nonstationary evaporation of water droplets in order to obtain a general dependence of the time of complete evaporation of droplets on the determining conditions.

Methodology. Operational calculus was used, in particular the Laplace integral transform.

Results. An equation has been obtained that allows one to calculate the time of complete evaporation of water droplets in a wide range of flow conditions around the droplets.

Research implications. The results of the work are significant both for conducting fundamental research on non-stationary evaporation of droplets in physical and chemical laboratories, and for practical use in a number of industries. 

Aim. Characterization of applied in tribotechnics thin film carbon containing coatings of different types and compositions, describing of principles of their work in tribological units and effects of their self-organization and ordering, which influence on friction coefficient and wear.

Methodology. Methods of analysis of literature data and classification of coatings under study in chemical composition, methods of their deposition, load conditions, classification of the methods and tribological tests conditions, classification of methods of characterization applied to coatings under study. Thermodynamical analysis of phase diagrams for carbon containing coatings on their compositions.

Results. We demonstrated the positive influence of alloying of carbon coatings applying in tribotechnical tasks: a required decreasing of friction coefficient and wear. Advantages and deficiencies of coatings with different types of alloying elements (for instance, metals of IV-B group, semiconductive elements and hydrogen) in different lubricants, friction units and conditions are estimated. An influence of ordering, particle morphology and their possible aggregation at the cost of carbon bounds sp1 , sp2 , sp3 and their combinations in coatings on tribological characteristics is proven.

Research implications. Practical implication of this study is an ascertainment of mechanisms of an influence of the alloying ingredients and ordering of particles, molecules and their aggregates in coatings on the friction coefficient, thereupon, optimization of contents of carbon coatings for different engineering specifications. 

Aim of this article is to consider algorithms for calculating stationary characteristics of queuing systems in computer classes using an Excel spreadsheet processor.

Methodology. A summary of this topic is provided. A general approach is given for calculating the stationary characteristics of queuing systems. The general approach is specified for queuing systems with failures, with a queue and with an unlimited queue.

Results. One of the ways of organizing classes in computer classes in the study of queuing systems is described.

Research implications. The practical significance of the work is due to the need to conduct classes on queuing systems for some areas of student training. In conditions of strict time constraints, classes can be organized in computer classes. The proposed approach can be used by teachers both in the classroom and when organizing students’ independent work, since it uses the simplest tools of the publicly available Excel spreadsheet processor.