Institute for Computer Aided Design

The rise of accuracy of the numerical methods and the appearance of high-performance computing systems has led to the application of such technologies to industrial geo-engineering problems, which include seismic prospecting. This is especially relevant to the harsh environments of the Arctic region rich with natural resources but costly in development. Therefore, numerical modeling is an efficient method to study occurring wave processes during the seismic survey and to relate them to the ground inhomogeneities, which became the main goal of the current work. In order to do this, a series of complex computational domains with curvilinear boundaries between inner layers of the ground are created to encompass the basic features of the region. A mathematical model of an isotropic linear elastic medium was used, describing the dynamic process of its deformation. Its governing system of equations in partial derivatives of the first order is hyperbolic. It is supplemented by zero initial conditions and the necessary linear boundary conditions. The problems of onshore and offshore seismology are solved using the grid-characteristic method. To achieve a reasonable computational time, parallel algorithms and research software with the support of the Message Passing Interface were developed. The problems of seismic wave propagation in a geological medium containing inclusions of ice and methane hydrate in a permafrost layer are solved numerically. Wave patterns and seismograms obtained can be used to improve the interpretation of field measurements. The used approach can be further applied to the construction of digital models of the ground.

Investigation of compression plasma flows impact on structure, phase, and elemental composition, as well as mechanical properties of Ti-6Al-4V titanium alloy with ZrN coating was carried out in this work. X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, samples weight measurements, microhardness and tribological tests were used as investigation techniques. The findings showed that plasma impact led to the formation of a composite surface layer based on titanium alloy containing inclusions of undissolved ZrN coating. Growth of the absorbed energy density resulted in a decrease of zirconium and nitrogen concentration in the surface layer due to erosion. Formation of solid solutions on the basis of α-Ti and β-Ti was found in the layer analyzed by X-ray diffraction. Presence of nitrogen in a vacuum chamber as plasma generating gas led to the formation of TiN on the surface. Plasma impact resulted in decrease of ZrN/Ti-6Al-4V system microhardness and decrease of friction coefficient (at specific treatment regimes).

The aim of the work is to create an algorithm for automatic graphological analysis of employees’ handwriting. The basis of the algorithm is parallel processing of the employees’ handwritten text. Implementing the presented algorithm will allow creating a modular automated system of graphological analysis. The article presents the architecture of an automated system of graphological analysis. The novelty of the work is the proposed creative concept of using automatic graphological analysis for timely detection of attempts of unfavourable external psychological influence on employees. The result of the study is recommendations for using the algorithm for graphological analysis of employees’ handwriting in automated information security systems.

The novel processing strategies of Equal Channel Angular Pressing (ECAP) combined with inter-pass aging was designed, and XRD, SEM, TEM, electrochemical testing, and hardness testing were used to evaluate the relationship between microstructure and performance of alloys in this work. The results indicate that the hardness uniformity of the circular cross-section perpendicular to the extrusion direction was improved by combining ECAP with inter-pass aging, resulting in a hardness inhomogeneity factor (∼0.030) that was lower than that achieved by peak aging and double-stage aging alloys. Polarization curves and electrochemical impedance spectra show that a more negative corrosion potential and a smaller corrosion current density were possessed by the alloy, with the maximum intergranular corrosion depth (IGC) being reduced to 38 μm. Microstructure observation indicates that the improvement in hardness uniformity is due to the uniformity of grain size and the improved distribution and size of the η’ phase, which is attributed to the interaction between the pinning and shear effects of precipitates and dislocations during deformation. The enhanced corrosion resistance was attributed to an orderly combination of deformation and aging that increases the grain boundary volume and disrupts the η phase continuity within grain boundaries.

The mathematical modeling of the selective laser melting process of metallic alloy powders for the construction of metal products has been carried out within the framework of the enthalpy formulation of the three-dimensional non-stationary nonlinear heat conductivity problem for a multiphase system. The parameters of the geometry of a single track, as well as single-layer and multilayer systems of overlapping tracks, depending on the power and speed of the laser beam have been determined that makes it possible to estimate the structure and types of defects occuring during layer-by-layer printing of specimens. To study the effect of single and multiple defects on the fatigue behavior of printed specimens under high-frequency loading, the previously proposed multi-mode model of cyclic damage has been used. It is shown that the internal heterogeneity of the microstructure of materials printed by selective laser melting can lead to earlier subsurface nucleation of fatigue cracks and significantly reduce the fatigue strength and durability. This effect is more pronounced for systems of multiple defects. The proposed models and calculation algorithms allow us to calculate the fatigue strength and durability of specimens for various systems of microstructure defects corresponding to the specified characteristics of a moving laser beam, as well as to determine the range of parameters of the selective laser melting process, in which the best fatigue strength indicators are achieved under high-frequency loading.

While studying at higher technical institutions, a student, when mastering professional types of activities from textbooks, requires awareness in acquiring a certain skill and experience. When teaching a student, his or her ability just to read and write is not enough, it is very important for him or her to be able to master the laws of developing technical systems and, after graduating from university, to use them in the future in their practical work.

The propagation of detonation waves (i.e., supersonic combustion waves) in non-uniform gaseous mixtures has become a matter of interest over the past several years due to the development of rotating detonation engines. It was shown in a number of recent theoretical studies of one-dimensional pulsating detonation that perturbation of the parameters in front of the detonation wave can lead to a resonant amplification of intrinsic pulsations for a certain range of perturbation wavelengths. This work is dedicated to the clarification of the mechanism of this effect. One-dimensional reactive Euler equations with single-step Arrhenius kinetics were solved. Detonation propagation in a gas with sine waves in density was simulated in a shock-attached frame of reference. We carried out a series of simulations, varying the wavelength of the disturbances. We obtained a non-linear dependence of the amplitude of these pulsations on the wavelength of disturbances with resonant amplification for a certain range of wavelengths. The gain in velocity was about 25% of the Chapman–Jouguet velocity of the stable detonation wave. The effect is explained using the characteristic analysis in the x-t diagram. For the resonant case, we correlated the pulsation period with the time it takes for the C+ and C− characteristics to travel through the effective reaction zone. A similar pulsation mechanism is realized when a detonation wave propagates in a homogeneous medium.

See the retraction notice BIO Web of Conferences 138, 00001 (2024), https://doi.org/10.1051/bioconf/202413800001

The material provides an introduction to preparing students’ teams to participate in the “Leaders of Digital Transformation” competition. An attempt has been made, from an architectural viewpoint, to consider the digital transformation of business, namely, the transition from automation architecture (Fig. 1) to digitalization architecture. The presentation is based on the material [1,2], which is expanded for students with drawings and links to additional literature.