The article presents the research of the loading regime of a membrane shell of an above-ground tunnel under the aerodynamic impact of a high-speed train. The authors solve the coupled problem of aerodynamics and deformable solid mechanics numerically by the Reynolds-averaged Navier-Stokes equations and the finite element method. Moreover, it is established that the governing loading parameters are the tunnel length and the relative
air gap, which controls the intensity of the piston effect. The maximum impact is produced by an alternatingsign pressure pulse in the region of the head nose cone; the tail zone is characterised by the developed turbulence and jet-separation flows. By the comparative analysis of smooth and corrugated shells, as well as a reinforced frame, the authors identify a structural solution combining aerodynamic efficiency and resistance to lateral loads. The service life under cyclic loading is assessed using the Palmgren-Miner damage accumulation rule and fatigue curves.

   The scientific novelty consists in a unified computational methodology integrating aerodynamic modeling, stress-strain analysis and fatigue assessment as applied to above-ground shell-type tunnels.

   The results are intended for optimizing geometric parameters and improving the durability of protective structures.

   The article addresses the pressing challenge of machining deep slot grooves and narrow cavities with widths of 3 mm or less in components used in aerospace and power engineering.

   Particular emphasis is placed on the insufficient rigidity and tendency to vibrate in elongated solid carbide end mills, especially when the length-to-diameter ratio L/D ˃ 5.

   These vibrations degrade surface quality, accelerate cutting edge wear, induce runout and often lead to tool failure. The authors analyse existing solutions and propose a new method to enhance tool rigidity: the use of a supporting steady rest (steady). This device acts as an additional support for the end mill, significantly increasing its stiffness and suppressing vibrations. The authors present results from mathematical modeling of the static rigidity of the tool system. One of the key advantages of this method is its technological simplicity and the ability to integrate it into existing CNC machines without major equipment overhaul. Unlike active damping systems, the method does not require complex electronics or specialized software. It enables the machining of deep, narrow slots even under highly unfavorable width-to-depth ratios-a task previously considered technologically challenging. Moreover, increased rigidity improves tool life and allows for higher cutting parameters, boosting productivity. This approach is particularly promising for machining parts made from heat-resistant alloys, where conventional milling techniques face significant limitations.

   The article presents a local modification method and an algorithm of the irregular point sets configuration in the Euclidean plane. Irregular point set is a set of vertices of some planar figure, specifically it becomes a broken line. The figure can be a base-set for some smooth planar peace-nonlinear curve. Numerical parameters or coordinates of the base-setare variable by given intervals, as well as the shape of the base-set. The local modification does not modify such metrical parameters of the base-set as length of sections and total length of the broken line. The authors introduce the concept of the admissible parametric local modification of the broken line. The admissible parametric local modification depends upon the number of variable points. In order to demonstrate the local modification the authors propose the hierarchic structuring of the base-set that means successive selection such sub-sets of adjacent points, which allow realizing the local modification of various number of parameters. The 0-, 1- and 2-parametric modifications are described in detail. The article shows two examples in order to illustrate the method. The first example describes the local modification of piece-linear segments of non-linear energy rays reflector. The aim of the segments modification is to change the direction of reflected rays. Local modification is implemented in light-guiding structure, in which flat section of reflecting surface consists of broken with fixed lengths of links. Discrete modifications of reflecting surface generate stepped distribution of energy illumination at receiver. The other example presents one of possible realizations and modification of the base-set for some accidental shape of some surface transverse section. The transverse section is a composite curve that simulates the section of a freely hanging fabric.

   The article introduces a wave hydrodiode — a passive hydraulic device in which periodic variation of the half-gap along the channel creates a difference in hydraulic resistance between forward and reverse flow directions. The profile of the flow section is defined by a cubic spline. The geometry is fully determined by three independent parameters: the minimum half-gap, the half-gap at the splice point, and the relative coordinate of the splice point. Numerical simulation is performed using Computational Fluid Dynamics methods based on steady-state Reynolds-averaged Navier–Stokes equations and the k–ω turbulence model. Differential-geometric analysis has shown that the zero fourth derivative of the cubic spline within each polynomial segment limits the reproduction of sharp curvature discontinuities necessary for effective vortex-based flow blocking. The obtained results demonstrate that spline parameterization is effective for smooth profiles, reducing the number of variable parameters, but requires replacement with discrete models for geometries with local edge aggressiveness. The findings lay the groundwork for multi-criteria topological optimization of passive shut-off devices for nuclear reactors.

   The study examines transient flow in a straight-tooth rotary pump when a rotor tooth progressively covers the suction and discharge ports.

   The aim is to improve prediction of instantaneous pressure in the working chamber by representing the actual variation in the open flow area instead of assuming instantaneous port closure.

   The formulation combines the Bernoulli and continuity equations with relations for frictional and local hydraulic losses. The changing port area is described as a circular segment whose dimensions depend on rotor position. The authors establish analytical relations between rotor angle, tooth position, effective flow area and the corresponding local resistance coefficient. Moreover, the research presents a calculation procedure that continuously accounts for changes in the suction and discharge flow areas during tooth passage. The derived expressions allow determining how hydraulic resistance and head losses vary with rotor position and pump geometry. Therefore, the model identifies angular regions associated with the greatest additional losses and provides a more detailed estimate of pressure variation within the working chamber. Explicit representation of partial port closure removes a simplifying assumption used in earlier models and improves the physical description of the transient process. The method can support optimization of tooth geometry and port dimensions and can be adapted to other positive-displacement hydraulic machines in which flow is controlled by moving elements. Further development should include experimental validation over a wider operating range and extensions accounting for liquid compressibility and cavitation.

   The article examines general trends in production approaches within the framework of the Industry 4.0, focusing on the printing industry. The analysis highlights the opportunities and constraints of integrating digital technologies into existing manufacturing systems. Findings indicate that the sector contends with high raw material costs, reliance on imported machinery and intense market competition. To ensure competitiveness, enterprises should boost productivity, minimize waste and develop their own intellectual property portfolios. The author conducts the research on the feasibility of manufacturing counter-matrices for cold embossing using 3D prototyping. The capabilities of additive technologies in the production of die sets — specifically counter-dies — are analysed. Fused Deposition Modeling (FDM), a layer-by-layer deposition technique, is selected for initial prototyping and printing of test objects to evaluate them with a set of quality criteria for counter-matrices. Moreover, the parameters for reproducing the linear dimensions of individual elements are verified using ABS and PLA materials compared with input geometric data. Therefore, the author confirms the compliance with acceptance criteria for industrial trials at an enterprise facility during the incoming inspection of the counter-matrices.

   In engineering geometry the problem of creating flexible curves incident to given points is relevant. The article describes a method for modeling interpolation curves in point calculus based on Bezier curves. The basis for modifying Bezier curves is replacing the simplex of control points in the curve equation with interpolation nodes. This method utilizes a uniform distribution of parameter values, ensuring that the incidence condition for the given points is satisfied. However, the use of Bezier curves does not always allow for the effective modeling of objects and processes with exponential change. Therefore, it is proposed to use the same method to define interpolation curves obtained from exponential functions in point calculus. The result is a new class of exponential interpolation curves which shape is determined using coefficients ki. The advantage of this approach is flexibility in shape control and the ability to create curves with predetermined geometric properties by solving minimax problems for the coefficients ki. The proposed method expands the geometric modeling toolkit in CAD systems and also it can be used for modeling and digitally supporting the lifecycle of complex products and forecasting processes with exponential growth.

   The article examines the process of adaptation of Russian civil aviation to the requirements of the Global Emissions Compensation and Reduction Scheme CORSIA in the context of sanctions restrictions since 2022. The authors analyse the current state of Russian preparations for the implementation of carbon regulation mechanisms considering the reorientation of international air transportation to the markets of the Global South, the closure of the airspace of unfriendly states and restrictions on the supply of aviation equipment.

   Special attention is paid to the technical aspects of creating a national monitoring, reporting and verification system compatible with the requirements of both International Civil Aviation Organization and potential BRICS and SCO partners.

   The legal risks of Russian airlines' participation in CORSIA and the prospects for the formation of alternative carbon accounting mechanisms are discussed.

   Therefore, it is necessary to develop a sovereign methodology for assessing the environmental impact of aviation based on domestic scientific schools and the regulatory framework.

   The article addresses the problem of functional-voxel modeling of a radar detection zone considering terrain effects. The author describes a principle for recalculating the local characteristics of the updated function by the use of local functions represented as V-representations of the radar detection zone and the terrain model. Moreover, the author defines the modeling space as a bounded domain and approximates by a regular discrete grid. The article performs the integration of the models using the R-function apparatus developed by Rvachev, which enables the implementation of set-theoretic operations such as intersections and joins in terms of ocal functions. This approach provides the construction of the resulting model in the form of a unified local analytical equation and ensures proper consideration of terrain-induced shielding effects in the formation of the detection zone. The software implementation demonstrates the applicability of the method with the discretization of 2003 voxels. The proposed approach can be applied to the analysis of spatial characteristics of radar coverage and to the development of software tools for modeling complex geometric stages.

   The article examines the problem of the justification of preliminary sizing and interconnection scheme for a distributed generation unit serving an area with abnormal power demand relative to the normative level. The research extends the previously completed stage of interval estimation of the technocenosis of municipal entities within the Prokopyevsky district of the Kemerovo Region (Kuzbass). The paper is dedicated to the subsequent optimization phase: the identification of the anomalous object, the normalization of its specific electricity consumption, and a preliminary engineering assessment of the local generating unit's
capacity.

   The object of the research is the Mayakovka village in the Kemerovo Region (Kuzbass).

   The authors perform the comparison of actual versus normalized specific electricity consumption basing on a continuous dataset spanning 48 months. The average magnitude by which actual values exceed the normative baseline is determined. It is shown that the equivalent average power of a compensating source amounts to approximately 28 kW; however, for more stable compensation of the additional energy demand, it is advisable to consider a preliminary design range for the installed capacity of 32–70 kW. The research substantiates an operating scheme for the local generation unit in parallel with the centralized grid, wherein the external network serves as the primary reserve. The results can be applied in the preliminary selection of distributed generation parameters for other rural areas with abnormal electricity consumption.

   The use of a magnetic pulse device for converting electrical energy into useful mechanical high-speed operation has great prospects for industrial applications. With high speed (1–5 ms) and low consumption (no more than 500 Wh) such installations allow achieving a high economic effect due to the electromagnetic force of mutual repulsion of the armature and the inductor. At the same time, the process of eddy currents in the armature, which is the fundamental process, has been poorly studied.

   The aim of the research is to study the processes of magnetic field and eddy current generation in the armature, measure their intensities, which ultimately leads to the emergence of a back-action force on the inducer's electromagnetic field that generated them.

   Thanks to the methods for modeling pulsed electromagnetic interaction considered in this article, it allows further regulating on full-scale samples a current pulse of certain amplitude, which creates Foucault currents (eddy currents) in the armature. It creates prerequisites for disrupting the adhesive bonds between the layers of the material being cleaned and the surface within the limits of elastic deformation zone, which constitutes the most relevant industrial application of a magnetic-pulse device. Thus, the mathematical framework for modeling physical processes in the ELCUT 6.0 Professional Software Package is based on the method of nodal potentials for magnetic and electric fields. The use of this method allows describing the distribution of the magnetic field and eddy current density in the armature with sufficient accuracy at all stages of pulsed action. The obtained simulation results provide a basis for further optimization of the design of the magnetic-pulse device and the well-reasoned selection of current pulse parameters that ensure maximum efficiency in disrupting adhesive bonds with minimal energy consumption.

   The paper examines the relevant issue of using neural network diagnostics as an auxiliary element of a set of measures to detect failures of the asynchronous electric drive of a vibratory jaw crusher used for crushing mineral fertilizers.

   A distinctive feature of this equipment is its ability to generate powerful vibration loads necessary for the effective destruction of the material, while maintaining the reliability and simplicity of the design.

   According to statistical data, up to 95 % of asynchronous motors installed in vibratory jaw crushers for crushing mineral fertilizers are machines with a power output ranging from 75 to 250 kW. These motors are most susceptible to the effects of aggressive environments, humidity, temperature fluctuations and increased vibration loads, which primarily leads to the failure of the mechanical parts of the equipment and the stator winding bars. The authors demonstrate the main problems of applying the method of neural network diagnostics of equipment and develop an algorithm for predicting failures of the actuator, namely, rod breakage in the phases of the stator of an asynchronous motor that operates as a drive for a vibrating jaw crusher of mineral fertilizers. Moreover, the research presents the assessment methodology with an expanded algorithm that allows eliminating a number of typical failures for this equipment, thereby increasing the efficiency of using an asynchronous electric drive in this industry. The research produced guidelines for operating and configuring the neural network algorithm designed to detect broken stator bars in an asynchronous motor.

   The article examines the development of technical and operational requirements for a sample preparation unit for a sorption-capacitive water dew point temperature transmitter in natural gas. The research shows that avoiding an additional methodological bias in water dew point temperature measurement requires preservation of the sample moisture content and single-phase state during sampling, throttling, transportation, and delivery to the measuring chamber. The paper analyses existing stationary and mobile systems for gas sampling, filtration and sample conditioning, as well as probe-type devices installed directly into pipelines. The authors demonstrate that known solutions primarily provide filtration, pressure and flow rate regulation, removal of interfering components or representative sampling from the stream, but only partially address the problem of thermal stabilization of the sample after throttling.

   A distinctive feature of the under consideration is the integration of functions within a single structural assembly: extracting the sample from a representative zone of the flow, throttling, protecting the throttling elements and performing intra-pipe thermal stabilization.

   The article outlines requirements for the mounting plate, heat exchange fin, impulse tubes with enhanced heat transfer, throttle valve, measuring chamber and construction materials. The authors show that the geometry of the immersion section, the surface area of heat exchangers, the length of the thermal stabilization tubes and the thermophysical properties of materials must be treated as interdependent parameters. These factors collectively determine the preservation of the sample's single-phase state and prevent any additional methodological bias in the water dew point temperature measurement results.

   Improving the precision of automatic control systems for process heaters is a critical factor in optimizing crude oil primary distillation units. The article introduces a dynamic mathematical model designed to maintain tight control over the outlet temperature, a vital parameter for subsequent high-quality fractionation.

   The object of the research is a gable barrel-type oil refinery furnace within a primary crude oil processing unit, featuring a temperature control loop for the petroleum product at the coil outlet based on fuel gas flow rate.

   The modeling is based on the synthesis of transfer functions of system elements: the temperature sensor is represented as a first-order lag element, the actuator — as an integrating element, the control valve — as an aperiodic link and the controlled process — as an aperiodic link.

   A distinctive feature of the proposed approach is the comprehensive consideration of physicochemical factors: the variable calorific value of the fuel gas calculated via the Wobbe index; the heat accumulation capacity of the fire tube walls; and the dependence of crude oil specific heat capacity on its moisture content.

   The simulation model is implemented in the SimInTech environment; the research is conducted using computational experiments involving the sequential application of step disturbances. Therefore, the authors conclude that with an increase in the feedstock inlet temperature by 50 °C, a 30 % rise in the mass flow rate of oil and a fivefold increase in moisture content, the controlled variable reaches extreme values of 410, 350 and 340 °C relative to the setpoint of 370 °C, with a regulation time not exceeding 15 000 seconds. The developed model enables minimization of technological regime deviations providing conditions for precise fractionation.