The paper analyzes dynamic characteristics of a four-wheeled mobile robot driven by omnidirectional mecanum wheels. To obtain information about dynamic characteristics of the robot, a computer model was developed in the MATLAB Simulink block modeling software environment. The constructed simulation model allowed to research the behavior of a holonomic mobile object with mecanum wheels in start-braking modes, based not only on its mathematical model, but also ta-king into account the weight and size parameters of the robot, introduced into the model through the integration of a three-dimensional digital prototype of the object. The investigation of the omnidirectional robot dynamics was considered within modeling the acceleration, uniform movement and deceleration of an object on a plane along a rectilinear trajectory. As a result, the dependences of kinematic, dynamic and mechanical characteristics were obtained, such as the dependence of angular velocity and torque of each wheel on time; the dependence of linear velocity of the robot's center of mass on time; the dependence of distance traveled by the robot on time; positioning errors while processing a given movement; spatial visualization of speed fluctuations. With the help of Mechanical Explorer tool, using a digital clone of the robot integrated into the model, an animation of the object’s movement along the trajectory was obtained. This approach, based on the integration of mathematical block and three-dimensional parametric models of the object with the possibility of visualization and animation of the results, allows to most fully investigate the dynamics and kinematics of nonlinear mechatronic systems. The obtained information of positioning errors and speed fluctuations in three coordinates allowed to conclude that there were random fluctuations during the robot’s movement, but their presence did not have a noticeable effect on the accuracy of the specified trajectory.

In this paper, a novel metamaterial-inspired microstrip antenna for wireless applications is proposed. The proposed design consists of a radiating path on top and a uniformly distributed split ring-shaped metamaterial structure on the ground. The presented antenna of 50´38 mm with a thickness of 1.6 mm is printed on FR₄ substrate and resonates at 1.80 GHz. The design was fabricated and the measured results were found to be in accordance with the simulations. The goal is accomplished by loading uniformly distributed split ring-shaped metamaterial structures on the ground plane of this antenna. The results of the experiments show that using the metamaterial structure on the ground plane improved gain from 4.34 to 7.3 dB, efficiency from 5.94 to 7.8 dB compared to the conventional patch antenna. This introduction in the ground plane exhibits return loss up to –38 dB and modified the gain and directivity to 7.3 and 7.8 dB respectively. The presented antenna has 45 MHz bandwidth. The presented design is proven by simulated surface current, S parameter, VSWR, radiation pattern. We have also investigated the effect of substrate permittivity, split width, and inter-element spacing in a split ring-shaped metamaterial structure on return loss. This directive antenna is designed for the applications of wireless local area networks and other Internet of things-based applications.

On the basis of the results of experimental studies the paper establishes important patterns of dependence of the frequency of short circuits of the arc gap and the coefficient of loss of electrode metal due to spatter from the voltage on the arc and the feed rate of the filler wire during welding and surfacing with the introduction of gaseous SF₆ into the Ar + CO₂ protective mixture. It is proposed to introduce fluorine-containing components of SF₆ directly into the protective gas mixture of 82 % Ar + 18 % CO₂ in quantities not exceeding 2 %. The technology makes it possible to reduce the amount of diffusion hydrogen in the deposited metal, which is an urgent task when welding high-strength steels and materials sensitive to hydrogen embrittlement. Previously, we resolved a number of issues related to the obstacle to increasing the concentration of S in the deposited metal, which made it possible to determine the most effective concentrations of SF6 in the protective gas environment, limited to 1.5 % by volume of the total composition (Ar + CO₂) + SF₆. At the same time, modification of the protective gas atmosphere with the halide compound SF₆ has a significant effect on the melting characteristics of the electrode wire and temperature indicators in the arc combustion zone. This is due to the high ionization potential of fluorine as a product of the high-temperature dissociation reaction of SF₆. The results obtained have made it possible to determine the most effective relationships between the values of the mode parameters, as well as to study the specifics of melting the filler wire in a protective atmosphere modified with SF6. Important regularities have been established that reveal the technological features of welding and surfacing with modification of the protective atmosphere with halide compounds.

The purpose of the work is an approximate computational and experimental assessment of the specific energy intensity and heat generation at various stages of the material’s operation when the sample is stretched. The paper discusses an approximate method for estimating the specific energy intensity and heat generation at four stages of tensile deformation of a steel sample. Finite element modeling of the work of the manufactured sample under elastic-plastic tension was performed in the ANSYS multifunctional software package. The load in the digital model of the sample was applied according to the full-scale test program. The experiment used flat samples in accordance with GOST 1497, a WAW-1000 testing machine with a 100T microcomputer, and a testo 875i thermal imager with a temperature sensitivity of 0.05 °C at 30 °C. We compared the obtained values on graphs of full-scale tests and a digital model of the samples, identifying critical points and deviation values. Phased loading revealed that the development of destruction occurs on the descending branches and is accompanied by the gradual development of local instability of plastic deformation in the form of a “neck”. It is shown that the heating temperature of the tensile metal can be calculated using the formulas proposed in the paper or by calculation using the ANSYS software package. The test results showed that the surface temperatures of the samples at each stage differ significantly. Four main areas were identified on the graph of changes in the sample surface temperature at a point. An analysis of the existing database of measuring instruments and the ability to obtain and process data was carried out. Experimental values of surface temperatures during continuous quasi-static deformation exceed their calculated values (up to 5 times). The kinetics of changes in the temperature field of the sample surface was carried out using thermographic instruments.

The paper considers the analysis of deformations in a statically indeterminate beam using the example of a ship's keel – an I-beam that plays an important role in ensuring the stability and structure of the vessel. The research is carried out through a combination of theoretical and experimental approaches. The force method was chosen for theoretical analysis as a universal tool for statically indeterminate beams, allowing to estimate deformations and stresses at various points of the beam. It includes the selection of the optimal cross section, which is an advantage of this approach. The finite element method (FEM), implemented using Ansys 2021 R2 PC, is used for experimental analysis and visualization of bending deformation. This method provides a more flexible and powerful tool for analyzing complex structures, taking into account a variety of boundary conditions. The results of the study were compared, and the calculation errors turned out to be minimal and acceptable. The paper emphasizes the importance of conducting such analyses to understand the behavior of structures under loads and ensure their reliability not only in transport, but also in industrial and civil construction.

Based on the experience accumulated to date in the use of backup spillways with eroded soil inserts and previously conducted studies, recommendations for the design and calculations of such structures are given. Four options for design and layout solutions are presented. The first option is that the eroded insert is located in the body of the earth dam. The erosion-limiting clothing is concrete. The second option is the same, but the erosion-limiting clothing is made of soft polymer material, for example, from geotextile or polymer film. According to the third option, the eroded insert is located in one or several spans of the surface spillway and operates like a “Hydroplus” gate. The fourth option is applicable under appropriate topographic conditions. Here, the eroded insert is located outside the pressure front, bypassing the dam and is a small eroded dam. A procedure for hydraulic calculations is proposed, which are performed in two stages. At the first stage, the dimensions of the spillway opening of the reserve spillway are determined to allow the design flow to pass through. Then, a calculation is made of the erosion of the soil insert located in this hole, which occurs when water overflows over its crest in an emergency. This calculation makes it possible to determine the time of erosion, as well as to construct a hydrograph of water flow through the eroded spillway, graphs of changes in the level of the headwaters and the marks of the crest of the insert during the erosion process. It is convenient to solve differential equations that describe the erosion process using a numerical method. A calculation algorithm is proposed.

If we consider asphalt concrete as a composite building material, consisting of heterogeneous components of different nature and properties, ensuring and controlling the connection between the matrix of the binder and the mineral frame is very important. This directly affects the most important technological and strength properties of the final material and the service life of the asphalt concrete road surface. The most common method for assessing adhesive bonds is a visual comparison of an asphalt concrete mixture boiled in water at a given temperature with an image of a reference sample. In our opinion, this control method is very subjective, since the test result is directly influenced by the researcher’s visual perception of the image. We have developed and described a test method that allows us to obtain an objective picture based on changes in the values of the water saturation index under vacuum-temperature influence. Using the developed methodology, studies were carried out on the adhesive properties of the binder before and after modification with various polymers and their compounds to stone material. For the research, asphalt concrete mixtures were selected, which are most often used as a coating material for the top layers of road pavements in the Republic of Belarus. Analysis of the data obtained showed the dependence of the risk of water penetration between bitumen and stone material with loss of adhesion of the binder to the aggregate on the development of the frame and the thickness of the bitumen film. The explanation for this phenomenon is that the percentage of cohesive delamination increases significantly with increasing bitumen film thickness and can reach 65% of cohesive delamination. At the same time, as the results of the study showed, preliminary modification of bitumen significantly reduces the negative consequences of vacuum-temperature effects on asphalt concrete.

Considering the increasingly large-scale application of magnetic fluids in various industries, we can confidently state that in the near future magnetorheological dampers will be widely used in adaptive automotive suspensions due to their operational flexibility and simplicity of controlling damping forces by changing the magnetic fluid properties according to parameters of surrounding electromagnetic field. The antivibration efficiency during operation is achieved by regulating the hydraulic resistance of the “magnetic” shock absorber by applying voltage to the windings of its coil. In addition to the physical properties of the oil used in the “magnetic” shock absorber, the viscosity of the working magnetorheological fluid is greatly influenced by the shape of the control signal. The paper focuses on the theoretical aspects of constructing a mathematical model of ac magnetorheological damper and presents the results of a computer experiment to assess effectiveness of its use as part of the adaptive suspension a passenger vehicle. In this case, the actual parameters of the “magnetic” shock absorber, used in modeling the dynamic process, were determined experimentally on a test bench, and the adequacy of the developed mathematical model was confirmed by the results of a semi-natural experiment. Using a verified model, the magnetorheological damper characteristics were obtained and compared for various forms of control signal, including rectangular voltage pulses of various frequencies and duty cycles, sinusoidal pulses and constant voltage signals. The analysis of the antivibration efficiency was carried out on the basis of the developed “quarter” model of a semi-active car suspension with a verified submodel of a magnetorheological damper integrated into its structure. Moreover, the simulation scenarios were based on the selected strategy for controlling the voltage supplied to the windings of the “magnetic” shock absorber. As the results of theoretical and experimental studies have shown in terms of energy consumption, expansion of the working area of the damping characteristic and achieving smooth control of the damping force, the most effective is the use of a sinusoidal pulse voltage signal in the control circuit, which ensures a reduction in both the amplitude and damping time of oscillations. However, when de-signing and manufacturing a controller, creating a pulse modulator for generating sinusoidal pulses coinciding in phase and frequency with the vibrations of the car body is very difficult due to the random nature of external disturbances from the road surface. When a constant voltage is applied to the magnetorheological damper winding, the damping properties of the suspension are also improved compared to the basic design based on a traditional hydraulic shock absorber. Moreover, there is a proportional relationship between the voltage supplying the damper, the amplitude and damping time of the vibrations of the car body is observed. An increase in the control signal voltage from 1 to 2 V leads, in comparison with passive control of a magnetic shock absorber, to a decrease in the maximum amplitude of vibrations of the car body by 6.25 and 11.25 %, respectively, and a decrease in the vibration damping time by 0.72 and 1.41 s.

The purpose of the study is to summarize the experience of forming Centers of Excellence in the USSR and the Russian Federation for the period from 1920 to the present on the basis of triune contexts. The research objectives are to identify the key tools for the formation and development of Centers of Excellence and compare the results of their use in order to identify the directions for improving state policy and the mechanism for strengthening them, taking into account the current economic situation and the strategic prospects for the country's development. The following research methods have been applied, namely: induction, deduction, analysis and synthesis, observation, comparison, systematization, description, empirical, evolutionary, systemic and historical-logical approach to the analysis of certain phenomena and processes. The results of the study have revealed the most effective mechanisms and tools for forming and stimulating the development of Centers of Excellence for the period from the 1920s to the present, and the paper also presents their evolution based on the use of triune contexts. The analysis has shown that it is advisable to take into account the experience of the USSR when developing the mechanism and selecting tools for the formation of Centers of Excellence in modern Russia.