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The paper presents the results of numerical simulation and experimental data on the high-speed penetration of the impactor into the obstacle. In the calculations, a discrete-element model has been used, based on the representation of the impactor and the target by a set of close packed interconnected particles. This class of models finds an increasingly wide application in the problems of high-speed interaction of bodies. In the previous works of the authors, the questions of application of the discrete-element model to the problem of the penetration of spherical impactors into massive targets were considered. On the basis of a comparative analysis of the data of computational and physical experiments, it was found out that for a wide class of high-speed penetration problems, a high accuracy of discrete-element modeling can be achieved using the two-parameter Lennard–Jones potential. The binding energy was identified as a function of the dynamic hardness of materials. It was shown that the use of this approach makes it possible to describe accurately the penetration process in the range of impactor velocities 500–2500 m/c.

In this paper, we compare the results of discrete-element modeling with experimental data on penetration of high-strength targets of different thickness by steel impactors. The use of computational parallelization technologies on graphic processors in combination with 3D visualization and animation of the results makes it possible to obtain detailed spatio-temporal patterns of the penetration process and compare them with experimental data.

A comparative analysis of the experimental and calculated data has shown a sufficiently high accuracy of discrete-element modeling for a wide range of target thicknesses: for thin targets pierced with preservation of the integrity of the deformed impactor, for targets of medium thickness, pierced with practically complete fragmentation of the impactor at the exit from the target, and for thick impenetrable targets.

We study an appearance of gravitational convection in a porous medium saturated by the double-diffusive fluid. The rectangle heated from below is considered with anisotropy of media properties. We analyze Darcy – Boussinesq equations for a binary fluid with Soret effect.

Resulting system for the stream function, the deviation of temperature and concentration is cosymmetric under some additional conditions for the parameters of the problem. It means that the quiescent state (mechanical equilibrium) loses its stability and a continuous family of stationary regimes branches off. We derive explicit formulas for the critical values of the Rayleigh numbers both for temperature and concentration under these conditions of the cosymmetry. It allows to analyze monotonic instability of mechanical equilibrium, the results of corresponding computations are presented.

A finite-difference discretization of a second-order accuracy is developed with preserving of the cosymmetry of the underlying system. The derived numerical scheme is applied to analyze the stability of mechanical equilibrium.

The appearance of stationary and nonstationary convective regimes is studied. The neutral stability curves for the mechanical equilibrium are presented. The map for the plane of the Rayleigh numbers (temperature and concentration) are displayed. The impact of the parameters of thermal diffusion on the Rayleigh concentration number is established, at which the oscillating instability precedes the monotonic instability. In the general situation, when the conditions of cosymmetry are not satisfied, the derived formulas of the critical Rayleigh numbers can be used to estimate the thresholds for the convection onset.

Ultrasound examination of material properties is a precision method for determining their elastic and strength properties in connection with the small wavelength formed in the material after impact of a laser beam. In this paper, the wave processes arising during these measurements are considered in detail. It is shown that full-wave numerical modeling allows us to study in detail the types of waves, topological characteristics of their profile, speed of arrival of waves at various points, identification the types of waves whose measurements are most optimal for examining a sample made of a specific material of a particular shape, and to develop measurement procedures.

To carry out full-wave modeling, a grid-characteristic method on structured grids was used in this work and a hyperbolic system of equations that describes the propagation of elastic waves in the material of the thin plate under consideration on a specific example of a ratio of thickness to width of 1:10 was solved.

To simulate an elastic front that arose in the plate due to a laser beam, a model of the corresponding initial conditions was proposed. A comparison of the wave effects that arise during its use in the case of a point source and with the data of physical experiments on the propagation of laser ultrasound in metal plates was made.

A study was made on the basis of which the characteristic topological features of the wave processes under consideration were identified and revealed. The main types of elastic waves arising due to a laser beam are investigated, the possibility of their use for studying the properties of materials is analyzed. A method based on the analysis of multiple waves is proposed. The proposed method for studying the properties of a plate with the help of multiple waves on synthetic data was tested, and it showed good results.

It should be noted that most of the studies of multiple waves are aimed at developing methods for their suppression. Multiple waves are not used to process the results of ultrasound studies due to the complexity of their detection in the recorded data of a physical experiment.

Due to the use of full wave modeling and analysis of spatial dynamic wave processes, multiple waves are considered in detail in this work and it is proposed to divide materials into three classes, which allows using multiple waves to obtain information about the material of the plate.

The main results of the work are the developed problem statements for the numerical simulation of the study of plates of a finite thickness by laser ultrasound; the revealed features of the wave phenomena arising in plates of a finite thickness; the developed method for studying the properties of the plate on the basis of multiple waves; the developed classification of materials.

The results of the studies presented in this paper may be of interest not only for developments in the field of ultrasonic non-destructive testing, but also in the field of seismic exploration of the earth's interior, since the proposed approach can be extended to more complex cases of heterogeneous media and applied in geophysics.

The results of the experimental and theoretical researches of kinetics of erythrosine penetration into collagenase molecules have represented in this paper. The case with introduction of the compound (fluorescent probe) which has dimers to enzyme solution as an injection has been considered. It was shown that monomers and dimers can penetrate into enzyme molecules with formation complexes monomer — enzyme, dimer- enzyme. Moreover, transformation of probe fluorescence spectra is at each time moment. Spectrum maximum shift, and its form change. At a time, the immobilized dye dimers greatly impact to formation of end fluorescence spectrum. Well correlation between experimental and theoretical results confirms reality of the obtained data.

In this work we have developed a new efficient program for the numerical simulation of 3D global chemical transport on an adaptive finite-difference grid which allows us to concentrate grid points in the regions where flow variables sharply change and coarsen the grid in the regions of their smooth behavior, which significantly minimizes the grid size. We represent the adaptive grid with a combination of several dynamic (tree, linked list) and static (array) data structures. The dynamic data structures are used for a grid reconstruction, and the calculations of the flow variables are based on the static data structures. The introduction of the static data structures allows us to speed up the program by a factor of 2 in comparison with the conventional approach to the grid representation with only dynamic data structures.

We wrote and tested our program on a computer with 6 CPU cores. Using the computer microarchitecture simulator gem5, we estimated the scalability property of the program on a significantly greater number of cores (up to 32), using several models of a computer system with the design “computational cores – cache – main memory”. It has been shown that the microarchitecture of a computer system has a significant impact on the scalability property, i.e. the same program demonstrates different efficiency on different computer microarchitectures. For example, we have a speedup of 14.2 on a processor with 32 cores and 2 cache levels, but we have a speedup of 22.2 on a processor with 32 cores and 3 cache levels. The execution time of a program on a computer model in gem5 is 104–105 times greater than the execution time of the same program on a real computer and equals 1.5 hours for the most complex model.

Also in this work we describe how to configure gem5 and how to perform simulations with gem5 in the most optimal way.

This article presents a classification of cities, taking into account their spatial planning and possible transport solutions for cities of various types. It also discusses examples of various strategies for the development of urban public transport in Russia and the European Union with a comparison of their efficiency. The article gives examples of the impact of urban planning on mobility of citizens. To implement complex strategic decisions, it is necessary to use micro and macro models which allow a comparison of situations “as is” and “as to be” to predict consequences. In addition, the authors propose a methodology to improve public transport route network and road network, which includes determining population needs in working and educational correspondences, identifying bottlenecks in the road network, developing simulation models and developing recommendations based on the simulation results, as well as the calculation of efficiency, including the calculation of a positive social effect, economic efficiency, environmental friendliness and sustainability of the urban transport system. To prove the suggested methodology, the macro and micro models of the city under study were built taking into account the spatial planning and other specifics of the city. Thus, the case study of the city of Naberezhnye Chelny shows that the use of our methodology can help to improve the situation on the roads by optimizing the bus route network and the road infrastructure. The results showed that by implementing the proposed solutions one can decrease the amount of transport load on the bottlenecks, the number of overlapping bus routes and the traffic density.

The study of the structural characteristics of composites and nanostructures is of fundamental importance in materials science. Theoretical and numerical modeling and simulation of the mechanical properties of nanostructures is the main tool that allows for complex studies that are difficult to conduct only experimentally. One example of nanostructures considered in this work are carbon nanotubes (CNTs), which have good thermal and electrical properties, as well as low density and high Young’s modulus, making them the most suitable reinforcement element for composites, for potential applications in aerospace, automotive, metallurgical and biomedical industries. In this review, we reviewed the modeling methods, mechanical properties, and applications of CNT-reinforced metal matrix composites. Some modeling methods applicable in the study of composites with polymer and metal matrices are also considered. Methods such as the gradient descent method, the Monte Carlo method, methods of molecular statics and molecular dynamics are considered. Molecular dynamics simulations have been shown to be excellent for creating various composite material systems and studying the properties of metal matrix composites reinforced with carbon nanomaterials under various conditions. This paper briefly presents the most commonly used potentials that describe the interactions of composite modeling systems. The correct choice of interaction potentials between parts of composites directly affects the description of the phenomenon being studied. The dependence of the mechanical properties of composites on the volume fraction of the diameter, orientation, and number of CNTs is detailed and discussed. It has been shown that the volume fraction of carbon nanotubes has a significant effect on the tensile strength and Young’s modulus. The CNT diameter has a greater impact on the tensile strength than on the elastic modulus. An example of works is also given in which the effect of CNT length on the mechanical properties of composites is studied. In conclusion, we offer perspectives on the direction of development of molecular dynamics modeling in relation to metal matrix composites reinforced with carbon nanomaterials.

In this paper the dynamic elasticity problem of the simultaneous normal and tangential impact on the half-space is solved. This problem simulates the oblique incidence of meteorite on the Earth’s surface. The surface Rayleigh wave is investigated. The resulting solution is used as an external effect on the high-rise building, located at some distance from the spot of falling for the safety and stability assessment of its structure. Numerical experiments were made based on the finite element software package STARK ES. Upper floors amplitudes of the selected object were calculated under such dynamic effects. Also a systematic comparison with the results at the foundation vibrations, relevant to  standard a 8-point earthquake accelerograms, was made.

A computer model describing the spatial-temporal dynamics of populations of interacting with renewable resource is proposed. The life cycle of the individual is described. The algorithm for spatial mobility of individuals within an area is proposed, which takes into account nutritional and social activity. The paper presents the computational experiments with the model that mimic the movement of herds of animals in the area, and describes the model experiment when the group type of animal behavior due to changes in the characteristics of the environment and animal behavior the herd animals is formed, which later goes again in the group type of animal behavior.

The well-known “Sea battle” game is in the focus of the current job. The main goal of the article is to provide modified version of “Sea battle” game and to find optimal players’ strategies in the new rules. Changes were applied to attacking strategies (new option to attack hitting four cells in one shot was added) as well as to the size of the field (sizes of 10 × 10, 20 × 20, 30 × 30 were used) and to the rules of disposal algorithms during the game (new possibility to move the ship off the attacking zone). The game was solved with the use of game theory capabilities: payoff matrices were found for each version of altered rules, for which optimal pure and mixed strategies were discovered. For solving payoff matrices iterative method was used. The simulation was in applying five attacking algorithms and six disposal ones with parameters variation due to the game of players with each other. Attacking algorithms were varied in 100 sets of parameters, disposal algorithms — in 150 sets. Major result is that using such algorithms the modified “Sea battle” game can be solved — that implies the possibility of finding stable pure and mixed strategies of behaviour, which guarantee the sides gaining optimal results in game theory terms. Moreover, influence of modifying the rules of “Sea battle” game is estimated. Comparison with prior authors’ results on this topic was made. Based on matching the payoff matrices with the statistical analysis, completed earlier, it was found out that standard “Sea battle” game could be represented as a special case of game modifications, observed in this article. The job is important not only because of its applications in war area, but in civil areas as well. Use of article’s results could save resources in exploration, provide an advantage in war conflicts, defend devices under devastating impact.