Donbass State Engineering Academy

The research is aimed at studying the features of strategy formulation in Formula One auto racing, the factors that influence this process, and identifying ways to increase the effectiveness of the strategy through the use of artificial intelligence methods. During Formula One races, teams face a large number of challenges related to various aspects, in particular tire wear and degradation. Teams deal with them through the implementation of the strategy – determining the correct pit stop moment and choosing the appropriate type of tires. Based on the determination of factors influencing the rate of tire wear and degradation, an original feature space was formed. Analysis of the strategies of race winners in previous seasons showed that the maximum number of pit stops was three. Using the principal component analysis, a study of the original feature space was conducted, the least relevant features were identified and subsequently removed from the original data set. To solve the problem, a system was proposed and built, consisting of four modules, each of which is a multilayer feedforward artificial neural network. Using the inequality proposed by Widrow and the sample-based estimation of the Lipschitz constant, the minimum required number of neurons of the hidden layers for each neural network module was determined. During the training process, their number was specified to achieve acceptable prediction results. AdaMax was used as an optimization algorithm, and the Huber loss function was chosen to calculate the error of the networks output. The mean squared error of the resulting system prediction on the test set was 0.1. The use of such system will reduce the decision-making time of teams when formulating a racing strategy, which in turn will contribute to achieving higher results in races.

The article provides and discusses details of numerical proceeding for the expansion method to calculate energy positions and wave functions of the localized and resonant electronic states emerging in quantum well-type semiconductor nanostructures because of perturbation of confined states by the Coulomb potential of the hydrogenic impurity center. Effective mass approximation is used. Several excited both resonant and non-resonant states are calculated and classified for the case of a simple rectangular GaAs/AlGaAs quantum well. Results are compared to the ones in literature.

The object of this study is the technological process of broaching cartridge cases through a radius die on a mandrel. The work is aimed at solving the actual scientific and technical task of improving the technological process of broaching on a mandrel through a die in the manufacture of cartridge-case type forgings, which provides an increase in the stability of broaching dies. The finite element method (FEM) was used to simulate the processes of broaching cartridge cases through the die. As a result, a rational geometry of the radius die has been established. Recommendations for designing new die structures have been devised, which involve determining the rational radius of rounding of the working part of the die. The established recommendations have been verified by experimental studies. The broaching of cartridge cases through a die with a working radius surface should be carried out at relative radius R/d=3.0. In this case, stress intensity decreased by 7...17 %, average compressive stresses decreased by 8...15 %, and normal pressure decreased by 10...15 % compared to smaller rounding radii. The resulting force on the working surface of the die decreased by 40...55 %, and the radial component of this force decreased by 50 %. It was found that the working surface of the die is heated to a temperature of 750...850 °C, but the rounding radius R/d=3.0 provides a reduction in the volume of this zone by 1.5...1.9 times. The resulting relative rounding radius of the die was tested under industrial conditions, which confirmed that the broaching force for this radius is lower by 15...20 %, and the stability of such a die increased by 20 %. It is recommended to use radius dies for broaching high cartridge cases. The results could also be applied at enterprises during the production of dual-purpose parts

Levchenko V. M., Aliiev I. S., Chepelenko O. Yu., Kartamyshev D. O., Malii O. G. Simulation of the process of transverse-forward extrusion with expansion Combined extrusion methods are a competitive solution for the production of complex-profiled and hollow parts in optimal power mode. By simulation of the combined transverse-forward extrusion process with using the energy method of kinematic modules, calculated correlations were obtained and an assessment of the influence of technological parameters on the deformation pressure was given. The possibility of considering the process of combined extrusion as sequentially composed one of two plane modules with the addition of normalized pressures of transverse and forward extrusion with expansion has been confirmed. For the transverse extrusion module the correlations obtained by the upper bound method and showing results close to experimental data and similar solutions for problems of plane upsetting (final stage of die forming) and differing in two types of discontinuous velocity field were used. For a rectangular module of forward extrusion with expansion, a discontinuous velocity field was constructed and the correlation for calculating the pressure components on the velocity discontinuity lines was obtained. It has been found that there is an optimal value for the angle of the triangular module in the range of 42–45°, according to which it is recommended to tilt the semi-die wall. A graphical analysis of the dependence of the normalized combined extrusion pressure has allowed to identify that the relative parameters have the greatest influence on the pressure level: the height of the transverse extrusion deformation zone h/R0 and the thickness of the ledge h/s, which characterize the degree of metal deformation. The correlations that make it possible to evaluate the influence of the relative wall thickness of a hollow product h/s on the normalized deformation pressure were experimentally confirmed on workpieces made of aluminum alloy AA1135.

Abstract The energy positions and wave function shapes of ground and excited impurity states including resonant ones are studied using expansion method. The structures under study are GaAs/AlGaAs rectangular quantum wells with four different widths. In all cases impurity binding energy (with respect to related subband) has a maximum at or near the center of the well, decreases when approaching to the barrier and seemingly has a limit of 0 if impurity moves away from the well. If impurity is displaced from the well center, then non-resonant impurity states wave functions within the well move closer to impurity center while the wave functions of the resonant states below the second subband move away from it. The effect is more pronounced for the ground and first resonant states respectively for the wider wells and reaches maximum near the halfway from center to barrier.

Abstract The article provides and discusses details of numerical proceeding for the expansion method to calculate energy positions and wave functions of the localized and resonant electronic states emerging in quantum well-type semiconductor nanostructures because of perturbation of confined states by the Coulomb potential of the hydrogenic impurity center. Effective mass approximation is used. Several excited both resonant and non-resonant states are calculated and classified for the case of a simple rectangular GaAs/AlGaAs quantum well. Results are compared to the ones in literature.

The article examines the history of concessions in Ukraine in comparison with the Polish concession experience. A concession is a specific form of attracting capital, combining the efforts of the state and private companies with the aim of building or improving capital-intensive and important facilities or providing socially useful services. The relevance of the problem of studying the concession experience of attracting capital in the form of concessions is noted (the adoption of the appropriate legislative framework in Ukraine and the start of the work of such enterprises). The broad geography and deep historical roots of the concessions are emphasized. Concession policy in Ukraine dates to the 19th century. It was found that in the history of our state there are both successfully implemented contracts and prematurely terminated concession agreements. It was noted that successful projects were an effective form of cooperation between the state and private capital. New enterprises were created that demonstrated high productivity. It was found that the Polish concession policy differed on a larger scale, the attitude towards the concessionaires was more loyal, the enterprises achieved high results. Ukrainian concession practice did not differ either in the scale of the projects or in their large number.

This work aims to conduct theoretical and experimental studies on the energy and force parameters of the separation process, as well as the geometric accuracy of the separated tubular workpiece using the "eccentric twisting" method. A mathematical model of a device with a "crank-circular" mechanism for cutting pipes by "eccentric twisting" has been developed. The technological process of cutting pipes by "eccentric twisting" was simulated using the DEFORM-3D software package. The results of experimental studies are in good agreement with the theoretical data calculated using the proposed mathematical model and the specialized program DEFORM-3D. The maximum differences between the cutting torque values obtained theoretically and experimentally do not exceed 6%. For the industrial implementation of research results, a design of an installation with a wedge-hinged drive with a concave wedge in combination with a "crank-circular" mechanism for separating pipes by the "eccentric torsion" scheme is proposed.