In this article, the coefficients of the nonlinear damping function of a mechanical system with one translational degree of freedom are determined from an experimentally obtained oscillogram of free vibrations. The function is modeled using three types of damping: coulomb damping, linear viscous, and nonlinear viscous damping. Numerical values of the damping coefficients are identified. The characteristic of the dissipative force as a function of displacement is obtained, and is used to find the amount of energy dissipated over a time period. An equivalent relative damping ratio is approximated using the energy balance method and then used to perform numerical integration of the equation of motion. A satisfactory match of the envelope curve and the phase of the vibrational process is demonstrated by comparing the calculated oscillogram to the experimental one. The damping function parameters can be further refined by approximating the experimental amplitudes. The obtained value of the relative damping coefficient can be used to solve nonlinear problems in the area of dynamics of weakly damped systems.

An algorithm for synthesizing hand motions of anthropomorphic robots by velocity vector during the installation of objects of manipulation given, in the form of rectangular prisms in a container, is proposed. The algorithm makes it possible to solve deadlock situations in computer simulation of motions. The essence of the method consists in the use of hand motions, at which the axis of the clash carrier moves and forms with some approximation a rulered surface, which specifies the body angle of service. For this purpose, it is proposed to use a database of configurations that specify certain positions of the output link centre and of the accumulation carrier axes which coincide with the above-mentioned line surfaces. The results of calculations of intermediate configurations in computer modeling of motions of anthropomorphic robots in an organized environment using the developed algorithm are presented.

The analysis of loaded state of system piston rod – piston of single-stage longstroke piston compressor is performed. These compressors are used to change the compressed gas pressure from normal atmospheric pressure (760 mmHg = =0,101 MPa) to discharge pressure (2–10 MPa). The criteria for calculating the piston rod from the point of view of its dynamics, taking into account the natural vibration frequency of the piston rod, are determined. Conclusions are drawn and practical recommendations are given that can be used in the design process of these compressor stages.

The article presents the results of studies of profile joints of mechanisms and machines for rigidity and strength. The device is based on the use of fixed and movable profile connections designed to transmit torque. Profile joints with a guaranteed gap are considered, made on the basis of an equiaxial contour of the P3, P5 type and a curved contour of the PC4 type, which have received the most widespread introduction in the nodes of metal-cutting machines and other machines manufactured in Russia, as well as Hungary, Germany and the DPRK.

Using a well-known technique designed to assess the stress-strain state (VAT) of the parts of profile joints, calculations are performed according to the criteria of operability for strength and stiffness of hubs (bushings) with different wall thicknesses. The analysis of the results of the calculation of strength and stiffness is carried out using the example of the P3 profile. When stretching the hub from the action of spacer forces, the geometric shape, the nominal size of the covered part, the wall thickness of the covering part, as well as the magnitude of the external load transmitted by the connection in static are taken into account. The permissible values of the thickness of the walls of the hub (bushings) of the joint are determined to ensure the rigidity of the hub under tension from the action of external loads. As a result of the research, the influence of the thickness of the hub walls for the studied shapes of the joint parts on the values of the transmitted torque is established. For example, a change in the thickness of the hub wall from 15 to 3 mm for a normal range of shaft mounting diameters causes the sleeve to stretch radially up to 50 microns in the range of transmitted torques from 5 to 600 Nm.

The purpose of the study is to find a technique and conduct on its basis a harmonic analysis of the torque of an internal combustion engine for the subsequent determination of resonant vibrations of the crankshaft. The method of calculating the harmonics of the engine torque is given on the example of a YaMZ-5340 diesel engine with a power of 100 kW at a crankshaft rotation speed of 2300 min-1. Based on the results of thermal and dynamic calculation of the YaMZ-5340 engine, a graph of changes in its torque is constructed and harmonics of the first and second orders are calculated. The frequencies of natural and forced vibrations of the crankshaft and its resonant critical rotation frequency are determined. The number of the torque harmonic has been determined, which, according to the frequency of forced vibrations, coincides with the frequency of natural vibrations and causes resonance. The results of the study can be applied in the design and fine-tuning of engines in order to calculate and reduce torsional vibrations.

The article provides a detailed algorithm for improving the C3D FairCurveModeler commands for constructing a class F spatial curve with approximation by a rational cubic spline Bezier curve (NURBzS-curve) and with approximation by a highdegree B-spline curve. The improvement is achieved by optimizing the structure of the Hermite spatial Geometric Determinant when defining it on a spatial virtual curve (V-curve) created on a set of double-tap conical curves. The structure of the Hermite Geometric Determinant is improved by changing the direction of the tangents, taking into account the spatial directions of the tangents at the end points of the conic segments at the step of constructing the set of double-tap conical curves.

To demonstrate the modified method, the work shows

1)       Improving the quality of a conical spiral modeled by the regular _Helix command of CAD systems ZWCAD, BricsCAD, AutoCAD by using the C3D FairCurveModeler command for creating a NURBzS-curve.

2)       Construction of a B-spline curve of the 8th degree on the points of a conical spiral by the C3D FairCurveModeler command and comparison with similar constructions in the CAD systems 'Rhino Ceros D', 'Alias Design Studio', NX which declare the construction of high quality curves (class A).

The results of a computer modeling of the distribution of wind flows near diverse objects (large-span and high-rise buildings) are given and analyzed. The analysis of pedestrian aerodynamic comfort is carried out for a vertical object (a high-rise building) separately and in two positions in combination with a horizontal one (a large span). Wind flow distribution fields are obtained. The results of the experiment show that complex buildings affect their distribution. The point of application and the modulus of the vector of the resultant wind load change. The speed and direction of distribution of wind flows near objects are changing. A nearby building located on the windward side creates a «barrier» reducing the wind speed in the courtyard areas. A building located downwind is able to reflect air flows, creating swirls near objects. More comfortable for external technical work on the facades of the buildings in question is the position from behind facing the direction of the wind flow.

Prompt receipt of reliable information about the terrain with sufficient detail is one of the main tasks in the fields of national economy, territorial development or research of large territorial units. The multiplicity of error sources in Earth remote sensing materials is due to a number of factors, and the resulting terrain models have a certain degree of generalization, which directly affects the correctness of digital terrain models. This article is devoted to the analysis of existing methods for estimating errors of open digital terrain models in order to increase their accuracy. Correct digital elevation models have a high similarity to reality and can be used in regional studies to determine the morphometric indicators of the territory.

A study of the boundaries of the working space of a three-link planar manipulator, specified by analytical equations, is carried out. A new geometric interpretation of these samples is proposed. On its basis, it is established that outer space consists of two-parameter volumes of eccentric and concentric circles. When transforming such environments into four-dimensional space, two types of hypersurfaces are obtained, which represent a geometric model of the manipulator's workspace. The discriminants of these hypersurfaces on the hyperplane are two two-dimensional surfaces. Both an analytical description of these surfaces and their computer models are obtained. As a result, it is established that the boundaries of the working space on the plane of the mechanism are the discriminants of such surfaces. To confirm the reliability of the results obtained, as an example, an inverse kinematics problem is solved on discriminant surfaces — the values of generalized coordinates at the boundary points of the manipulator’s workspace are determined for their given Cartesian coordinates.

Modern energy systems are increasingly integrating renewable energy sources, presenting new challenges for voltage regulation. This study aims to model the voltage regulation process in the context of distributed electrical grids equipped with solar photovoltaic systems. A three-tier voltage control algorithm is proposed, which analyzes and integrates data on solar generation, suggests optimal actions for managing energy storage systems, calculates voltage levels, and recommends measures for controlling inverter reactive power to effectively mitigate voltage fluctuations. The study employs methods of mathematical averaging of time series and optimization based on the analysis of real data. The algorithm's performance is evaluated using an open dataset of solar energy generation. The results show a significant improvement in voltage regulation metrics, conforming to the standards established by GOST 32144-2013. This validates the effectiveness of the proposed voltage control method in electrical grids incorporating solar photovoltaic systems.

The article analyzes existing schemes of chaos generators. Numerical and simulation modeling is carried out aimed at identifying chaotic dynamics. Based on wellknown concepts, a chaos generator is developed and a simulation model is built. A mathematical description of the generator is given and phase portraits are obtained. Diagrams of chaotic oscillations of the Lorentz model and the Colpitts model are presented. The operation of the Van der Pol generator is considered and the chaotic processes that arise during external harmonic oscillations are shown. Chua's model is presented, its mathematical description is given, and an analysis of oscillations in the deterministic chaos regime is presented.

In overhead lines of power supply systems at voltages of 6–110 kV, the use of protected wires is becoming increasingly popular, which have a number of advantages over traditional non-insulated aluminum wires. On the other hand, the presence of insulation requires the development of more complex mathematical models to adequately describe their behavior and study the characteristics of new wires during operation.

The results of using the developed mathematical models and calculation programs for comparative analysis of protected and non-insulated wires under conditions of changing load currents and weather conditions are presented. The dependences of temperature and loss of active power on insulation thickness are investigated. It is shown that the presence of insulation allows, under certain conditions, to reduce temperature and losses compared to wires without insulation, all other things being equal.

The results obtained can be used to increase the capacity and reliability of power transmission lines.

The paper is devoted to the study of the dependences of the characteristics of partial discharges on magnetic induction. The design of the experimental setup has been developed. It allows applying both high voltage and current comparable to the operating one. The setup includes a high voltage source (dielectric tester), a current flow circuit, a high voltage current transformer and a sample of XLPE insulated cable. The operation of the electrical circuit of the experimental setup is simulated using software. The modeling has shown that if the operational electrical strength of the current transformer insulation is present, the high-voltage potential cannot contact the current flow circuit. After this, modeling of the magnetic field inside the insulating layer is carried out. Based on the developed design, an experimental setup is created. To record partial discharges, an artificial defect is created in a cable sample. The results of magnetic field modeling made it possible to estimate the magnetic induction in the field of an artificial cable defect. Next, experimental studies are carried out to assess the influence of the magnetic field of the cable core current on the characteristics of partial discharges. The measurement results have showed a decrease in the average apparent charge of partial discharges and partial discharge power with increasing current. In addition, waveforms are compared, but no significant differences are found. The magnetic field of the current may influence the PD performance in the long term due to its possible influence on the direction of growth of the electrical tree structure.

The article has obtained an analytical solution to the thermal conductivity equation for the contact connection of long sections of overhead lines, and also considered the case for a line with two short and two long sections, which makes it possible to take into account distributed defects and clamp sizes. The application of the obtained mathematical model to determine the temperature of an overhead power line near contact connections is shown. A comparative analysis of the temperature values in the power line, calculated using the created mathematical model, with published data obtained based on finite element modeling using the results of a physical experiment is performed. It has been shown that heating of contact connections can significantly limit the throughput of lines even at an acceptable level of contact resistance. This makes relevant the tasks of calculating the temperature of contact connections of power lines and clarifying permissible currents taking into account the influence of transient contact resistances.

The work provides a comparative study of double and dual electric field strength sensors. The comparison examined the design, technological and metrological parameters of the sensors, as well as the complexity of their measuring circuits. Research has revealed similarities in the design and technological parameters of the sensors and differences in metrological characteristics and the complexity of the measuring circuits. In terms of metrological characteristics, dual sensors are significantly superior to double ones. It has been established that a dual sensor having sensitive elements with angular dimensions q₁=46,38 °, and q2=90 °, has a smaller error due to field inhomogeneity. The error does not exceed d£½ ±2,76½ % in the spatial measurement range 0£a£1. With the same error, double sensors can only be used in a limited spatial measurement range of 0£a£0,89. It is shown that dual sensors are superior to dual sensors in terms of metrological parameters. This indicates the advisability of their use.

The article considers a flow-through electrochemical cell with planar interdigitated microelectrodes intended for impedance studies of liquids. To assess the influence of the cell height and geometric parameters of the interdigitated microelectrodes on the cell impedance, an analytical approach is proposed that uses several levels of modeling electrochemical processes in the cell. At first, an elementary two-dimensional subdomain is distinguished in the cell structure, for which the potential distribution is determined by solving the differential equation of electrical conductivity. Using the obtained potential distribution, the linear parameters of the elementary subdomain, its linear resistance and linear capacitance are determined, on the basis of which the resistance and capacitance of the interdigitated microelectrode system are found. The impedance of an electrochemical cell with interdigitated microelectrodes is determined using its equivalent electrical circuit, which includes the resistance and capacitance of the interdigitated microelectrode system, the capacitance of the double electric layer on the surface of each microelectrode, and the resistances of the interdigitated microelectrode leads. Using the expression for the impedance of the electrochemical cell, its Nyquist and Bode diagrams are determined for different values of the cell height and geometric parameters of the interdigitated microelectrode system. The presented approach can be used to analyze processes in a flow-through electrochemical cell with interdigitated microelectrodes, its design, and the development of methodological support for impedance studies of liquid substances with help of it.

The article provides an overview of the known effects that influence the transmission of information over optical fiber and that arise as a result of lightning discharges: the electro-optical Kerr effect, the Faraday effect, the influence of ionizing radiation. It is indicated that there is preliminary empirical data according to which the magnetic field changes such an optical fiber parameter as attenuation. In order to verify these preliminary empirical data, further experimental studies of the supposed influence of the magnetic field on attenuation are proposed, for which it is necessary to build a laboratory installation. This article is also devoted to a comparison of various options for laboratory installations and the preliminary selection of a parameter for comparison. As a result of modeling two options for a laboratory installation and comparing them according to the accepted parameter, one of two installation options is selected.

Reinforced concrete structures play a key role in modern infrastructure, however, corrosion of reinforcement poses a serious threat to their durability and safety. In this study, the sensitivity of a portable X-ray fluorescence analyzer (XRF) to corrosion products on the concrete surface is considered. The experiment was conducted using concrete samples containing varying amounts of iron hydroxide. The results showed that the FRA demonstrates high accuracy and reliability in detecting corrosion, which contributes to the improvement of diagnostic methods and maintenance of reinforced concrete structures.

This paper discusses a new method for measuring and calculating the angle of inclination of a railway support or a contact network support, using an unmanned aerial vehicle flying along a straight path, parallel to the railway track. A review of existing measurement methods is carried out, their advantages and disadvantages are indicated. In the method under consideration, it is proposed to measure angles and distances with six laser scanning rangefinders installed in threes on horizontal and inclined planes on an unmanned aerial vehicle. This allows you to increase the speed and accuracy of determining the angle of inclination of vertical supports. The calculations use the minimum distances from the laser scanning range finder to the top and bottom of the support surface. The formulas use geometric relationships and the cosine theorem to calculate the roll of supports taking into account their taper. Measuring distances and angles three times allows for averaging over them, which significantly increases the accuracy of calculations. A model experiment is carried out on a model of a reinforced concrete contact network support in four orientations. A comparison is made between theoretically calculated and experimentally measured distances and inclination angles. The accuracy of parameter determination complies with regulatory requirements.