The study is devoted to ensuring the safety of mainline oil and gas pipelines operated beyond their normative service life in the Republic of Belarus, through their inspection and subsequent restorative heat treatment of circumferential welded joints. During the operation of oil and gas pipelines, the impact toughness of the pipe metal and especially of its welded joints decreases. This leads to an increased likelihood of crack initiation and growth and to subsequent catastrophic failure of the main oil and gas pipeline. In this regard, a new restorative repair process is proposed that includes a specialized heat treatment of the material of pipeline joints exhibiting reduced impact toughness. Based on an experimental-statistical model of impact-toughness recovery, technological parameters for performing the special heat treatment of welded joints in the main oil and gas pipelines operated beyond their normative service life were determined. Under specified regimes, the restorative repair process can provide a relative increase in material impact toughness of up to 50 % and an increase in corrosion resistance of up to 4 %. A diagnostic method for the linear sections of a main oil and gas pipeline is proposed, based on determining the material’s impact toughness and thereby identifying the timing for shutdown to carry out repairs. This method is distinguished by the use of the Lagrange interpolation polynomial that relates pipeline operating time to changes in impact toughness; it reduces calculation error and establishes the possibility of a two-fold extension of service life following restorative repair by the special heat treatment.

The processes of granulation, crushing, and grinding of raw materials, most widely used in the mining industry in the processing of minerals, are implemented in centrifugal grinders with high-speed impact action which leads to rapid wear of the replaceable parts of centrifugal crushing and grinding equipment. One of such parts is an impact plate manufactured at the Institute of Technology of Metals of the National Academy of Sciences of Belarus from wear-resistant chromium cast iron grade ИЧХ18ВМ [IChKh18VM]. Geometrically they look like a parallelepiped with a square cross-sectional size of 7.0–8.5 cm. A five-layer casting of such part in a specially designed chill mold has been used aiming to change its microstructure which is awaited to raize its wear resistance. Numerical simulation of heat exchange in the casting-chill mold system has shown that, in contrast to continuous pouring in the overheat removal section, the temperature dynamics in the depth of the casting has a non-monotonic periodic nature. The microstructure features of the "impact plate" have been studied during five-layer pouring into a chill mold. It is shown that the features of the change in the melt temperature during the pouring process make it possible to consider multilayer pouring as an analogue of thermal cycling of liquid metal above the solidus temperature. It has been established that such treatment provides a significant increase in the dispersion and uniformity of the microstructure over the casting cross-section compared to a single pouring. The areas of pearlite decomposition are distributed more uniformly over the casting cross-section compared to a single pouring. The reason may be a more uniform distribution of cementite nuclei during the decomposition of austenite under thermal cycling conditions due to an increase in the austenite-carbide interface in ledeburite. An increase in the homogeneity of the structure ensures equalization of hardness over the casting crosssection. The tested method of layer-by-layer casting is promising for increasing the wear resistance and strength of parts of impact plates and inserts for centrifugal crushing and grinding equipment.

This article considers a contact problem for a rectangular stamp located on an elastic homogeneous isotropic octant and loaded with a vertical force. Shear stresses are ignored at the contact between the stamp and the octant. First, an expression is derived for the vertical displacements of the octant boundary due to a concentrated vertical force as a superposition of solutions for two symmetrically loaded quarter-spaces and a half-space. In this case, the influence of Poisson's ratio in determining the displacements is taken into account. Next, the stamp is then calculated using B. N. Zhemochkin's method. To achieve this, the contact surface of the stamp is divided into identical rectangular sections and rigid rods are placed at the center of each section, through which the stamp contacts the elastic octant. This statically indeterminate system is solved using a mixed method of structural mechanics, where the unknowns are the forces in the rigid rods and the linear and angular displacements of the clamping force introduced at the center of the stamp. The coefficients for the unknown forces are determined by integrating the resulting expression for the displacements over the area of the rectangular section. The first term, representing the Boussinesq solution and containing a singularity, is integrated exactly, while the remaining terms, represent ting continuous smooth functions, are integrated numerically. An example calculation for a square stamp located on the apex of an octant during its translational movement is given. The contact stress surface and lines of equal stress are presented. A comparison with a similar problem for a half-space is made using the M. I. Gorbunov-Posadov formula. A previously unknown phenomenon of tensile contact stresses under the stamp near the octant tip was noted.

This article provides an overview of the evolution, current technologies, and future trends for the development of methods for measuring lactate concentration in human blood. Lactate, as a key metabolite of carbohydrate metabolism, serves as an important biomarker for the diagnosis of hypoxia, assessment of effectiveness of therapy in intensive care, and analysis of metabolic responses to physical activity in sports medicine. The historical progression of methods – from titrimetric and colorimetric approaches to enzymatic and electrochemical technologies – is analyzed in detail. Particular emphasis is placed on enzymatic methods using lactate dehydrogenase and lactate oxidase, which laid the foundation for modern portable point-of-care analyzers. The paper examines the operational principles, advantages and limitations of chemical, enzymatic, electrochemical and microfluidic systems, including lab-on-a-chip devices and wearable sensors for continuous real-time monitoring. It has been shown that the development of point-of-care and microfluidic technologies has transformed lactatometry from a laboratory-based procedure into an integrated component of intelligent and personalized metabolic monitoring systems. It was noted that the key research directions include the standardization of analytical procedures, improvement of measurement reproducibility, the development of non-invasive and multiplex sensors, and the application of artificial intelligence algorithms for data interpretation and predictive modeling. The results of the review highlight the growing role of lactate measurement in both clinical diagnostics and elite sports performance monitoring.

The paper presents three variants of installation schemes for circulating-reagent treatment of water intake well screens, which allow to use both liquid and powder reagents. The main components of the installations are: a reagent tank, one or two reagent pumps connected in series, a pipeline system, a jet pump installed under the liquid level in the water intake well, and a corrugated plastic pipe placed with an annular gap inside the screen being cleaned. The task of the process equipment is to create targeted circulation of the reagent outside the corrugated pipe in the screen and near-screen zone of the well that has reduced the flow rate. This ensures efficient and uniform processing of the screen, reduces the volume of reagent migration into the aquifer. A calculation scheme for reagent movement in the system (reagent tank – screen – riser pipe – jet pump – reagent tank) has been developed. A system of equations for reagent movement has been compiled. The paper describes a methodology for calculating a system of equations using a graph-analytical method, which allows one to obtain the values of the circulation flow rate and flushing speed in a concentric annular channel between the internal surfaces of a screen and a corrugated plastic pipe. The methodology also allows to select the parameters of the technological equipment of the installation for processing water intake wells with a given depth and position of the static water level. An example of calculation is given.

This study addresses the urgent issue of improving the durability of Stone Mastic Asphalt pavements, where a key technological challenge is binder drainage at high manufacturing temperatures. Existing solutions based on costly imported stabilizing additives create significant economic barriers to their widespread use. The objective of this research was to develop and scientifically validate an optimal formulation for a cost-effective composite stabilizing additive based on locally available raw materials, including cellulose fiber from waste paper and polymer fiber from industrial waste. To solve this multifactorial optimization problem, the method of multiple regression analysis was employed. The experimental basis for the modeling was derived from laboratory tests on 16 additive formulations with varying component proportions. The independent variables (factors) included the percentages of synthetic fiber, cellulose, and a thermal stabilizer, as well as the final dosage of the additive in the asphalt mix. The dependent variables (responses) were key performance indicators such as binder drainage, tensile strength at 0 °C, and compressive strength at 50 °C. As a result of the study, three linear regression models describing the “composition-property” relationships were developed. The high predictive capability of the models was confirmed by statistical metrics; the coefficient of determination R2 for all equations exceeded 0.90, indicating a high degree of explained variance. Based on these models, an optimization problem with specified criteria and constraints was solved, allowing for the analytical determination of the optimal ranges for component content. Verification of the predictions against strong agreement showed a nearly perfect match between calculated and experimental data. A scientifically validated and patented final additive composition was developed, which ensures compliance with asphalt concrete standards and serves as a competitive alternative to existing analogues.

In the context of growing geopolitical tensions worldwide and the increasing frequency of terrorist attacks employing high-precision weapons and unmanned aerial vehicles (UAVs), ensuring the security of critical infrastructure facilities is becoming an increasingly urgent task. The scientific novelty of the work lies in the development and substantiation of a comprehensive protection system, which, alongside the modular buildings themselves, incorporates passive safety means (armored panels and protective enclosing structures). The study substantiates that modular construction technology provides an optimal foundation for creating new facilities, as it combines rapid installation, factory quality, cost-effectiveness, and the capability to integrate passive protection means. The main objective of this work is to develop a concept for a comprehensive protection system for critical infrastructure facilities, capable of withstanding both direct attacks by high-precision weapons and secondary effects (fragmentation damage from explosions, fires, etc.). The primary research tasks include: analyzing the advantages of modular construction technology, evaluating existing passive protection solutions, developing an integrated protection concept compatible with the specifics of modular structures, and justifying technical requirements for its components. To achieve this goal, an analysis of scientific and regulatory literature on the design of modular buildings, bullet-resistant elements, and protective enclosing structures was conducted. The outcome of the work comprises well-founded technical proposals for applying modular construction technologies in combination with bullet-resistant panels and protective enclosing structures. Implementing the developed concept will enable the creation of a flexible and resilient infrastructure capable of operating in high-risk areas. Furthermore, the proposed system ensures not only protection against UAV attacks but also minimizes risks to the life and health of personnel inside the protected building. The obtained results can be subsequently used by manufacturers of modular buildings to enhance design solutions and implement integrated protection at the new construction stage.

Zonal methods for calculating drying time, based on graphical differentiation of the drying curve, are presented. An analysis of drying time calculation based on the drying rate curve is given using the methods of A. V. Lykov, V. V. Kras nikov, S. M. Smirnov, B. S. Sazhin, and P. S. Kuts. The methods for calculating the drying time based on the relative drying rate without using the drying rate curve are considered. A generalized dimensionless drying curve as a function of the genera lized drying time is given based on the method of generalized drying curves of G. K. Filonenko and V. V. Krasnikov. Possible methods for approximating the equation of a generalized drying curve by hyperbolic, power, and exponential dependencies are considered. The necessary conditions are given for determining the suitability of these dependencies for describing the equations of the drying curves and deriving the equations. Equations of the drying curve are obtained from these dependencies and formulas are given for calculating the drying time for the processes of drying ceramics, asbestos, and felt. Based on the dependence of the complex variable of the relative drying rate on the ratio of the current to the initial moisture content, for the processes of drying ceramics, asbestos, and felt, equations are given for calculating the drying time. The methods for expres sing the drying curve in the form of dependencies of relative moisture content on the generalized drying time are considered. Methods for calculating the drying time based on the relative drying rate are presented. Based on the dependence of the rela tive drying rate on the dimensionless moisture content, approximate methods for determining the critical moisture content of the material are given. The reliability of the obtained equations is checked and the calculated values are compared with the experiment. The calculation error is within the range of experimental accuracy.